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Date:   Tue, 15 Jun 2021 10:36:38 +0000
From:   Anand Ashok Dumbre <ANANDASH@...inx.com>
To:     Alexandru Ardelean <ardeleanalex@...il.com>
CC:     Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio <linux-iio@...r.kernel.org>,
        git-dev <git-dev@...inx.com>, Michal Simek <michals@...inx.com>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        devicetree <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Manish Narani <MNARANI@...inx.com>
Subject: RE: [PATCH v5 2/4] iio: adc: Add Xilinx AMS driver

Hi Alexandru,

Thanks for reviewing the patch.

> -----Original Message-----
> From: Alexandru Ardelean <ardeleanalex@...il.com>
> Sent: Monday 31 May 2021 5:13 PM
> To: Anand Ashok Dumbre <ANANDASH@...inx.com>
> Cc: Jonathan Cameron <jic23@...nel.org>; Lars-Peter Clausen
> <lars@...afoo.de>; linux-iio <linux-iio@...r.kernel.org>; git-dev <git-
> dev@...inx.com>; Michal Simek <michals@...inx.com>; Peter Meerwald-
> Stadler <pmeerw@...erw.net>; devicetree
> <devicetree@...r.kernel.org>; LKML <linux-kernel@...r.kernel.org>;
> Manish Narani <MNARANI@...inx.com>
> Subject: Re: [PATCH v5 2/4] iio: adc: Add Xilinx AMS driver
> 
> (()
> 
> On Fri, May 28, 2021 at 8:31 PM Anand Ashok Dumbre
> <anand.ashok.dumbre@...inx.com> wrote:
> >
> > The AMS includes an ADC as well as on-chip sensors that can be used to
> > sample external voltages and monitor on-die operating conditions, such
> > as temperature and supply voltage levels. The AMS has two SYSMON
> blocks.
> > PL-SYSMON block is capable of monitoring off chip voltage and
> > temperature.
> > PL-SYSMON block has DRP, JTAG and I2C interface to enable monitoring
> > from external master. Out of these interface currently only DRP is
> > supported.
> > Other block PS-SYSMON is memory mapped to PS.
> > The AMS can use internal channels to monitor voltage and temperature as
> > well as one primary and up to 16 auxiliary channels for measuring
> > external voltages.
> > The voltage and temperature monitoring channels also have event
> > capability which allows to generate an interrupt when their value falls
> > below or raises above a set threshold.
> >
> > Signed-off-by: Manish Narani <manish.narani@...inx.com>
> > Signed-off-by: Anand Ashok Dumbre <anand.ashok.dumbre@...inx.com>
> > ---
> >  drivers/iio/adc/Kconfig      |   13 +
> >  drivers/iio/adc/Makefile     |    1 +
> >  drivers/iio/adc/xilinx-ams.c | 1341
> ++++++++++++++++++++++++++++++++++
> >  3 files changed, 1355 insertions(+)
> >  create mode 100644 drivers/iio/adc/xilinx-ams.c
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index c7946c439612..c011ab30ec9a 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -1256,4 +1256,17 @@ config XILINX_XADC
> >           The driver can also be build as a module. If so, the module will be
> called
> >           xilinx-xadc.
> >
> > +config XILINX_AMS
> > +       tristate "Xilinx AMS driver"
> > +       depends on ARCH_ZYNQMP || COMPILE_TEST
> > +       depends on HAS_IOMEM
> > +       help
> > +         Say yes here to have support for the Xilinx AMS.
> > +
> > +         The driver supports Voltage and Temperature monitoring on Xilinx
> Ultrascale
> > +         devices.
> > +
> > +         The driver can also be built as a module. If so, the module will be
> called
> > +         xilinx-ams.
> > +
> >  endmenu
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index a226657d19c0..99e031f44479 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -112,4 +112,5 @@ obj-$(CONFIG_VF610_ADC) += vf610_adc.o
> >  obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
> >  xilinx-xadc-y := xilinx-xadc-core.o xilinx-xadc-events.o
> >  obj-$(CONFIG_XILINX_XADC) += xilinx-xadc.o
> > +obj-$(CONFIG_XILINX_AMS) += xilinx-ams.o
> >  obj-$(CONFIG_SD_ADC_MODULATOR) += sd_adc_modulator.o
> > diff --git a/drivers/iio/adc/xilinx-ams.c b/drivers/iio/adc/xilinx-ams.c
> > new file mode 100644
> > index 000000000000..0c84f7a9fc80
> > --- /dev/null
> > +++ b/drivers/iio/adc/xilinx-ams.c
> > @@ -0,0 +1,1341 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Xilinx AMS driver
> > + *
> > + *  Copyright (C) 2017-2018 Xilinx, Inc.
> 
> 2021 ?  😝

Oops. Will fix.
> 
> > + *
> > + *  Manish Narani <mnarani@...inx.com>
> > + *  Rajnikant Bhojani <rajnikant.bhojani@...inx.com>
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/iopoll.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +#include <linux/iio/events.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +
> > +static const unsigned int AMS_UNMASK_TIMEOUT_MS = 500;
> > +
> > +/* AMS registers definitions */
> > +#define AMS_ISR_0                      0x010
> > +#define AMS_ISR_1                      0x014
> > +#define AMS_IER_0                      0x020
> > +#define AMS_IER_1                      0x024
> > +#define AMS_IDR_0                      0x028
> > +#define AMS_IDR_1                      0x02c
> > +#define AMS_PS_CSTS                    0x040
> > +#define AMS_PL_CSTS                    0x044
> > +
> > +#define AMS_VCC_PSPLL0                 0x060
> > +#define AMS_VCC_PSPLL3                 0x06C
> > +#define AMS_VCCINT                     0x078
> > +#define AMS_VCCBRAM                    0x07C
> > +#define AMS_VCCAUX                     0x080
> > +#define AMS_PSDDRPLL                   0x084
> > +#define AMS_PSINTFPDDR                 0x09C
> > +
> > +#define AMS_VCC_PSPLL0_CH              48
> > +#define AMS_VCC_PSPLL3_CH              51
> > +#define AMS_VCCINT_CH                  54
> > +#define AMS_VCCBRAM_CH                 55
> > +#define AMS_VCCAUX_CH                  56
> > +#define AMS_PSDDRPLL_CH                        57
> > +#define AMS_PSINTFPDDR_CH              63
> > +
> > +#define AMS_REG_CONFIG0                        0x100
> > +#define AMS_REG_CONFIG1                        0x104
> > +#define AMS_REG_CONFIG3                        0x10C
> > +#define AMS_REG_SEQ_CH0                        0x120
> > +#define AMS_REG_SEQ_CH1                        0x124
> > +#define AMS_REG_SEQ_CH2                        0x118
> > +
> > +#define AMS_TEMP                       0x000
> > +#define AMS_SUPPLY1                    0x004
> > +#define AMS_SUPPLY2                    0x008
> > +#define AMS_VP_VN                      0x00c
> > +#define AMS_VREFP                      0x010
> > +#define AMS_VREFN                      0x014
> > +#define AMS_SUPPLY3                    0x018
> > +#define AMS_SUPPLY4                    0x034
> > +#define AMS_SUPPLY5                    0x038
> > +#define AMS_SUPPLY6                    0x03c
> > +#define AMS_SUPPLY7                    0x200
> > +#define AMS_SUPPLY8                    0x204
> > +#define AMS_SUPPLY9                    0x208
> > +#define AMS_SUPPLY10                   0x20c
> > +#define AMS_VCCAMS                     0x210
> > +#define AMS_TEMP_REMOTE                        0x214
> > +
> > +#define AMS_REG_VAUX(x)                        (0x40 + 4*(x))
> > +
> > +#define AMS_PS_RESET_VALUE             0xFFFF
> > +#define AMS_PL_RESET_VALUE             0xFFFF
> > +
> > +#define AMS_CONF0_CHANNEL_NUM_MASK     GENMASK(6, 0)
> > +
> > +#define AMS_CONF1_SEQ_MASK             GENMASK(15, 12)
> > +#define AMS_CONF1_SEQ_DEFAULT          (0 << 12)
> > +#define AMS_CONF1_SEQ_CONTINUOUS       (2 << 12)
> > +#define AMS_CONF1_SEQ_SINGLE_CHANNEL   (3 << 12)
> > +
> > +#define AMS_REG_SEQ0_MASK              0xFFFF
> > +#define AMS_REG_SEQ2_MASK              0x003F
> > +#define AMS_REG_SEQ1_MASK              0xFFFF
> > +#define AMS_REG_SEQ2_MASK_SHIFT                16
> > +#define AMS_REG_SEQ1_MASK_SHIFT                22
> > +
> > +#define AMS_REGCFG1_ALARM_MASK         0xF0F
> > +#define AMS_REGCFG3_ALARM_MASK         0x3F
> > +
> > +#define AMS_ALARM_TEMP                 0x140
> > +#define AMS_ALARM_SUPPLY1              0x144
> > +#define AMS_ALARM_SUPPLY2              0x148
> > +#define AMS_ALARM_SUPPLY3              0x160
> > +#define AMS_ALARM_SUPPLY4              0x164
> > +#define AMS_ALARM_SUPPLY5              0x168
> > +#define AMS_ALARM_SUPPLY6              0x16c
> > +#define AMS_ALARM_SUPPLY7              0x180
> > +#define AMS_ALARM_SUPPLY8              0x184
> > +#define AMS_ALARM_SUPPLY9              0x188
> > +#define AMS_ALARM_SUPPLY10             0x18c
> > +#define AMS_ALARM_VCCAMS               0x190
> > +#define AMS_ALARM_TEMP_REMOTE          0x194
> > +#define AMS_ALARM_THRESHOLD_OFF_10     0x10
> > +#define AMS_ALARM_THRESHOLD_OFF_20     0x20
> > +
> > +#define AMS_ALARM_THR_DIRECT_MASK      0x01
> > +#define AMS_ALARM_THR_MIN              0x0000
> > +#define AMS_ALARM_THR_MAX              0xffff
> > +
> > +#define AMS_NO_OF_ALARMS               32
> > +#define AMS_PL_ALARM_START             16
> > +#define AMS_ISR0_ALARM_MASK            0xFFFFFFFFU
> > +#define AMS_ISR1_ALARM_MASK            0xE000001FU
> > +#define AMS_ISR1_EOC_MASK              0x00000008U
> > +#define AMS_ISR1_INTR_MASK_SHIFT       32
> > +#define AMS_ISR0_ALARM_2_TO_0_MASK     0x07
> > +#define AMS_ISR0_ALARM_6_TO_3_MASK     0x78
> > +#define AMS_ISR0_ALARM_12_TO_7_MASK    0x3F
> > +#define AMS_CONF1_ALARM_2_TO_0_SHIFT   1
> > +#define AMS_CONF1_ALARM_6_TO_3_SHIFT   5
> > +#define AMS_CONF3_ALARM_12_TO_7_SHIFT  8
> > +
> > +#define AMS_PS_CSTS_PS_READY           0x08010000U
> > +#define AMS_PL_CSTS_ACCESS_MASK                0x00000001U
> > +
> > +#define AMS_PL_MAX_FIXED_CHANNEL       10
> > +#define AMS_PL_MAX_EXT_CHANNEL         20
> > +
> > +#define AMS_INIT_TIMEOUT_US            10000
> > +
> > +/*
> > + * Following scale and offset value is derived from
> > + * UG580 (v1.7) December 20, 2016
> > + */
> > +#define AMS_SUPPLY_SCALE_1VOLT         1000
> > +#define AMS_SUPPLY_SCALE_3VOLT         3000
> > +#define AMS_SUPPLY_SCALE_6VOLT         6000
> > +#define AMS_SUPPLY_SCALE_DIV_BIT       16
> > +
> > +#define AMS_TEMP_SCALE                 509314
> > +#define AMS_TEMP_SCALE_DIV_BIT         16
> > +#define AMS_TEMP_OFFSET                        -((280230L << 16) / 509314)
> > +
> > +enum ams_alarm_bit {
> > +       AMS_ALARM_BIT_TEMP,
> > +       AMS_ALARM_BIT_SUPPLY1,
> > +       AMS_ALARM_BIT_SUPPLY2,
> > +       AMS_ALARM_BIT_SUPPLY3,
> > +       AMS_ALARM_BIT_SUPPLY4,
> > +       AMS_ALARM_BIT_SUPPLY5,
> > +       AMS_ALARM_BIT_SUPPLY6,
> > +       AMS_ALARM_BIT_RESERVED,
> > +       AMS_ALARM_BIT_SUPPLY7,
> > +       AMS_ALARM_BIT_SUPPLY8,
> > +       AMS_ALARM_BIT_SUPPLY9,
> > +       AMS_ALARM_BIT_SUPPLY10,
> > +       AMS_ALARM_BIT_VCCAMS,
> > +       AMS_ALARM_BIT_TEMP_REMOTE
> > +};
> > +
> > +enum ams_seq {
> > +       AMS_SEQ_VCC_PSPLL,
> > +       AMS_SEQ_VCC_PSBATT,
> > +       AMS_SEQ_VCCINT,
> > +       AMS_SEQ_VCCBRAM,
> > +       AMS_SEQ_VCCAUX,
> > +       AMS_SEQ_PSDDRPLL,
> > +       AMS_SEQ_INTDDR
> > +};
> > +
> > +enum ams_ps_pl_seq {
> > +       AMS_SEQ_CALIB,
> > +       AMS_SEQ_RSVD_1,
> > +       AMS_SEQ_RSVD_2,
> > +       AMS_SEQ_TEST,
> > +       AMS_SEQ_RSVD_4,
> > +       AMS_SEQ_SUPPLY4,
> > +       AMS_SEQ_SUPPLY5,
> > +       AMS_SEQ_SUPPLY6,
> > +       AMS_SEQ_TEMP,
> > +       AMS_SEQ_SUPPLY2,
> > +       AMS_SEQ_SUPPLY1,
> > +       AMS_SEQ_VP_VN,
> > +       AMS_SEQ_VREFP,
> > +       AMS_SEQ_VREFN,
> > +       AMS_SEQ_SUPPLY3,
> > +       AMS_SEQ_CURRENT_MON,
> > +       AMS_SEQ_SUPPLY7,
> > +       AMS_SEQ_SUPPLY8,
> > +       AMS_SEQ_SUPPLY9,
> > +       AMS_SEQ_SUPPLY10,
> > +       AMS_SEQ_VCCAMS,
> > +       AMS_SEQ_TEMP_REMOTE,
> > +       AMS_SEQ_MAX
> > +};
> > +
> > +#define AMS_SEQ(x)             (AMS_SEQ_MAX + (x))
> > +#define AMS_VAUX_SEQ(x)                (AMS_SEQ_MAX + (x))
> > +
> > +#define AMS_PS_SEQ_MAX         AMS_SEQ_MAX
> > +#define PS_SEQ(x)              (x)
> > +#define PL_SEQ(x)              (AMS_PS_SEQ_MAX + (x))
> > +
> > +#define AMS_CHAN_TEMP(_scan_index, _addr) { \
> > +       .type = IIO_TEMP, \
> > +       .indexed = 1, \
> > +       .address = (_addr), \
> > +       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > +               BIT(IIO_CHAN_INFO_SCALE) | \
> > +               BIT(IIO_CHAN_INFO_OFFSET), \
> > +       .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> > +       .event_spec = ams_temp_events, \
> > +       .num_event_specs = ARRAY_SIZE(ams_temp_events), \
> > +       .scan_index = (_scan_index), \
> > +       .scan_type = { \
> > +               .sign = 'u', \
> > +               .realbits = 12, \
> > +               .storagebits = 16, \
> > +               .shift = 4, \
> > +               .endianness = IIO_CPU, \
> > +       }, \
> > +}
> > +
> > +#define AMS_CHAN_VOLTAGE(_scan_index, _addr, _alarm) { \
> > +       .type = IIO_VOLTAGE, \
> > +       .indexed = 1, \
> > +       .address = (_addr), \
> > +       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > +               BIT(IIO_CHAN_INFO_SCALE), \
> > +       .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> > +       .event_spec = (_alarm) ? ams_voltage_events : NULL, \
> > +       .num_event_specs = (_alarm) ? ARRAY_SIZE(ams_voltage_events) : 0,
> \
> > +       .scan_index = (_scan_index), \
> > +       .scan_type = { \
> > +               .realbits = 10, \
> > +               .storagebits = 16, \
> > +               .shift = 6, \
> > +               .endianness = IIO_CPU, \
> > +       }, \
> > +}
> > +
> > +#define AMS_PS_CHAN_TEMP(_scan_index, _addr) \
> > +       AMS_CHAN_TEMP(PS_SEQ(_scan_index), _addr)
> > +#define AMS_PS_CHAN_VOLTAGE(_scan_index, _addr) \
> > +       AMS_CHAN_VOLTAGE(PS_SEQ(_scan_index), _addr, true)
> > +
> > +#define AMS_PL_CHAN_TEMP(_scan_index, _addr) \
> > +       AMS_CHAN_TEMP(PL_SEQ(_scan_index), _addr)
> > +#define AMS_PL_CHAN_VOLTAGE(_scan_index, _addr, _alarm) \
> > +       AMS_CHAN_VOLTAGE(PL_SEQ(_scan_index), _addr, _alarm)
> > +#define AMS_PL_AUX_CHAN_VOLTAGE(_auxno) \
> > +       AMS_CHAN_VOLTAGE(PL_SEQ(AMS_VAUX_SEQ(_auxno)), \
> > +                       AMS_REG_VAUX(_auxno), false)
> > +#define AMS_CTRL_CHAN_VOLTAGE(_scan_index, _addr) \
> > +
> AMS_CHAN_VOLTAGE(PL_SEQ(AMS_VAUX_SEQ(AMS_SEQ(_scan_index))),
> \
> > +                       _addr, false)
> > +
> > +struct ams {
> > +       void __iomem *base;
> > +       void __iomem *ps_base;
> > +       void __iomem *pl_base;
> > +       struct clk *clk;
> > +       struct device *dev;
> > +       struct mutex lock;
> > +       unsigned int alarm_mask;
> > +       unsigned int masked_alarm;
> > +       u64 intr_mask;
> > +       int irq;
> > +       struct delayed_work ams_unmask_work;
> > +};
> > +
> > +static inline void ams_ps_update_reg(struct ams *ams, unsigned int
> offset,
> > +                                    u32 mask, u32 data)
> > +{
> > +       u32 val;
> > +
> > +       val = readl(ams->ps_base + offset);
> > +       writel((val & ~mask) | (data & mask), ams->ps_base + offset);
> > +}
> > +
> > +static inline void ams_pl_update_reg(struct ams *ams, unsigned int
> offset,
> > +                                        u32 mask, u32 data)
> > +{
> > +       u32 val;
> > +
> > +       val = readl(ams->pl_base + offset);
> > +       writel((val & ~mask) | (data & mask), ams->pl_base + offset);
> > +}
> > +
> > +static void ams_update_intrmask(struct ams *ams, u64 mask, u64 val)
> > +{
> > +       ams->intr_mask &= ~mask;
> > +       ams->intr_mask |= (val & mask);
> > +
> > +       writel(~(ams->intr_mask | ams->masked_alarm), ams->base +
> AMS_IER_0);
> > +       writel(~(ams->intr_mask >> AMS_ISR1_INTR_MASK_SHIFT),
> > +                       ams->base + AMS_IER_1);
> > +       writel(ams->intr_mask | ams->masked_alarm, ams->base +
> AMS_IDR_0);
> > +       writel(ams->intr_mask >> AMS_ISR1_INTR_MASK_SHIFT,
> > +                       ams->base + AMS_IDR_1);
> > +}
> > +
> > +static void ams_disable_all_alarms(struct ams *ams)
> > +{
> > +       /* disable PS module alarm */
> > +       if (ams->ps_base) {
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG1,
> AMS_REGCFG1_ALARM_MASK,
> > +                                 AMS_REGCFG1_ALARM_MASK);
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG3,
> AMS_REGCFG3_ALARM_MASK,
> > +                                 AMS_REGCFG3_ALARM_MASK);
> > +       }
> > +
> > +       /* disable PL module alarm */
> > +       if (ams->pl_base) {
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> > +                                   AMS_REGCFG1_ALARM_MASK,
> > +                                   AMS_REGCFG1_ALARM_MASK);
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG3,
> > +                                   AMS_REGCFG3_ALARM_MASK,
> > +                                   AMS_REGCFG3_ALARM_MASK);
> > +       }
> > +}
> > +
> > +static void ams_update_alarm(struct ams *ams, unsigned long
> alarm_mask)
> > +{
> > +       u32 cfg;
> > +       unsigned long pl_alarm_mask;
> > +
> > +       if (ams->ps_base) {
> > +               /* Configuring PS alarm enable */
> > +               cfg = ~((alarm_mask & AMS_ISR0_ALARM_2_TO_0_MASK) <<
> > +                              AMS_CONF1_ALARM_2_TO_0_SHIFT);
> > +               cfg &= ~((alarm_mask & AMS_ISR0_ALARM_6_TO_3_MASK) <<
> > +                               AMS_CONF1_ALARM_6_TO_3_SHIFT);
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG1,
> AMS_REGCFG1_ALARM_MASK,
> > +                                 cfg);
> > +
> > +               cfg = ~((alarm_mask >> AMS_CONF3_ALARM_12_TO_7_SHIFT) &
> > +                               AMS_ISR0_ALARM_12_TO_7_MASK);
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG3,
> AMS_REGCFG3_ALARM_MASK,
> > +                                 cfg);
> > +       }
> > +
> > +       if (ams->pl_base) {
> > +               pl_alarm_mask = (alarm_mask >> AMS_PL_ALARM_START);
> > +               /* Configuring PL alarm enable */
> > +               cfg = ~((pl_alarm_mask & AMS_ISR0_ALARM_2_TO_0_MASK) <<
> > +                              AMS_CONF1_ALARM_2_TO_0_SHIFT);
> > +               cfg &= ~((pl_alarm_mask & AMS_ISR0_ALARM_6_TO_3_MASK)
> <<
> > +                               AMS_CONF1_ALARM_6_TO_3_SHIFT);
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> > +                               AMS_REGCFG1_ALARM_MASK, cfg);
> > +
> > +               cfg = ~((pl_alarm_mask >> AMS_CONF3_ALARM_12_TO_7_SHIFT)
> &
> > +                               AMS_ISR0_ALARM_12_TO_7_MASK);
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG3,
> > +                               AMS_REGCFG3_ALARM_MASK, cfg);
> > +       }
> > +
> > +       mutex_lock(&ams->lock);
> > +       ams_update_intrmask(ams, AMS_ISR0_ALARM_MASK,
> ~alarm_mask);
> > +       mutex_unlock(&ams->lock);
> > +}
> > +
> > +static void ams_enable_channel_sequence(struct iio_dev *indio_dev)
> > +{
> > +       int i;
> > +       unsigned long long scan_mask;
> > +       struct ams *ams = iio_priv(indio_dev);
> > +
> > +       /*
> > +        * Enable channel sequence. First 22 bits of scan_mask represent
> > +        * PS channels, and next remaining bits represent PL channels.
> > +        */
> > +
> > +       /* Run calibration of PS & PL as part of the sequence */
> > +       scan_mask = 0x1 | BIT(AMS_PS_SEQ_MAX);
> > +       for (i = 0; i < indio_dev->num_channels; i++)
> > +               scan_mask |= BIT(indio_dev->channels[i].scan_index);
> > +
> > +       if (ams->ps_base) {
> > +               /* put sysmon in a soft reset to change the sequence */
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                                 AMS_CONF1_SEQ_DEFAULT);
> > +
> > +               /* configure basic channels */
> > +               writel(scan_mask & AMS_REG_SEQ0_MASK,
> > +                               ams->ps_base + AMS_REG_SEQ_CH0);
> > +               writel(AMS_REG_SEQ2_MASK &
> > +                       (scan_mask >> AMS_REG_SEQ2_MASK_SHIFT),
> > +                       ams->ps_base + AMS_REG_SEQ_CH2);
> > +
> > +               /* set continuous sequence mode */
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                                 AMS_CONF1_SEQ_CONTINUOUS);
> > +       }
> > +
> > +       if (ams->pl_base) {
> > +               /* put sysmon in a soft reset to change the sequence */
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                                   AMS_CONF1_SEQ_DEFAULT);
> > +
> > +               /* configure basic channels */
> > +               scan_mask = scan_mask >> AMS_PS_SEQ_MAX;
> > +               writel(scan_mask & AMS_REG_SEQ0_MASK,
> > +                               ams->pl_base + AMS_REG_SEQ_CH0);
> > +               writel(AMS_REG_SEQ2_MASK &
> > +                               (scan_mask >> AMS_REG_SEQ2_MASK_SHIFT),
> > +                               ams->pl_base + AMS_REG_SEQ_CH2);
> > +               writel(AMS_REG_SEQ1_MASK &
> > +                               (scan_mask >> AMS_REG_SEQ1_MASK_SHIFT),
> > +                               ams->pl_base + AMS_REG_SEQ_CH1);
> > +
> > +               /* set continuous sequence mode */
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                               AMS_CONF1_SEQ_CONTINUOUS);
> > +       }
> > +}
> > +
> > +static int ams_init_device(struct ams *ams)
> > +{
> > +       u32 reg;
> > +       int ret;
> > +
> > +       /* reset AMS */
> > +       if (ams->ps_base) {
> > +               writel(AMS_PS_RESET_VALUE, ams->ps_base + AMS_VP_VN);
> > +
> > +               ret = readl_poll_timeout(ams->base + AMS_PS_CSTS, reg,
> > +                                        (reg & AMS_PS_CSTS_PS_READY) ==
> > +                                        AMS_PS_CSTS_PS_READY, 0,
> > +                                        AMS_INIT_TIMEOUT_US);
> > +               if (ret)
> > +                       return ret;
> > +
> > +               /* put sysmon in a default state */
> > +               ams_ps_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                                 AMS_CONF1_SEQ_DEFAULT);
> > +       }
> > +
> > +       if (ams->pl_base) {
> > +               writel(AMS_PL_RESET_VALUE, ams->pl_base + AMS_VP_VN);
> > +
> > +               ret = readl_poll_timeout(ams->base + AMS_PL_CSTS, reg,
> > +                                        (reg & AMS_PL_CSTS_ACCESS_MASK) ==
> > +                                        AMS_PL_CSTS_ACCESS_MASK, 0,
> > +                                        AMS_INIT_TIMEOUT_US);
> > +               if (ret)
> > +                       return ret;
> > +
> > +               /* put sysmon in a default state */
> > +               ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                                   AMS_CONF1_SEQ_DEFAULT);
> > +       }
> > +
> > +       ams_disable_all_alarms(ams);
> > +
> > +       /* Disable interrupt */
> > +       ams_update_intrmask(ams, ~0, ~0);
> > +
> > +       /* Clear any pending interrupt */
> > +       writel(AMS_ISR0_ALARM_MASK, ams->base + AMS_ISR_0);
> > +       writel(AMS_ISR1_ALARM_MASK, ams->base + AMS_ISR_1);
> > +
> > +       return 0;
> > +}
> > +
> > +static int ams_enable_single_channel(struct ams *ams, unsigned int
> offset)
> > +{
> > +       u8 channel_num = 0;
> > +
> > +       switch (offset) {
> > +       case AMS_VCC_PSPLL0:
> > +               channel_num = AMS_VCC_PSPLL0_CH;
> > +               break;
> > +       case AMS_VCC_PSPLL3:
> > +               channel_num = AMS_VCC_PSPLL3_CH;
> > +               break;
> > +       case AMS_VCCINT:
> > +               channel_num = AMS_VCCINT_CH;
> > +               break;
> > +       case AMS_VCCBRAM:
> > +               channel_num = AMS_VCCBRAM_CH;
> > +               break;
> > +       case AMS_VCCAUX:
> > +               channel_num = AMS_VCCAUX_CH;
> > +               break;
> > +       case AMS_PSDDRPLL:
> > +               channel_num = AMS_PSDDRPLL_CH;
> > +               break;
> > +       case AMS_PSINTFPDDR:
> > +               channel_num = AMS_PSINTFPDDR_CH;
> > +               break;
> > +       default:
> > +               return -EINVAL;
> > +       }
> > +
> > +       /* set single channel, sequencer off mode */
> > +       ams_ps_update_reg(ams, AMS_REG_CONFIG1,
> AMS_CONF1_SEQ_MASK,
> > +                       AMS_CONF1_SEQ_SINGLE_CHANNEL);
> > +
> > +       /* write the channel number */
> > +       ams_ps_update_reg(ams, AMS_REG_CONFIG0,
> AMS_CONF0_CHANNEL_NUM_MASK,
> > +                       channel_num);
> > +       return 0;
> > +}
> > +
> > +static int ams_read_vcc_reg(struct ams *ams, unsigned int offset, u32
> *data)
> > +{
> > +       u32 reg;
> > +       int ret;
> > +
> > +       ret = ams_enable_single_channel(ams, offset);
> > +       if (ret)
> > +               return ret;
> > +
> > +       ret = readl_poll_timeout(ams->base + AMS_ISR_1, reg,
> > +                                (reg & AMS_ISR1_EOC_MASK) == AMS_ISR1_EOC_MASK,
> > +                                0, AMS_INIT_TIMEOUT_US);
> > +       if (ret)
> > +               return ret;
> > +
> > +       *data = readl(ams->base + offset);
> > +
> > +       return 0;
> > +}
> > +
> > +static int ams_read_raw(struct iio_dev *indio_dev,
> > +                       struct iio_chan_spec const *chan,
> > +                       int *val, int *val2, long mask)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       int ret;
> > +
> > +       switch (mask) {
> > +       case IIO_CHAN_INFO_RAW:
> > +               mutex_lock(&ams->lock);
> > +               if (chan->scan_index >= (AMS_PS_SEQ_MAX * 3)) {
> > +                       ret = ams_read_vcc_reg(ams, chan->address, val);
> > +                       if (ret) {
> > +                               mutex_unlock(&ams->lock);
> > +                               return -EINVAL;
> > +                       }
> > +                       ams_enable_channel_sequence(indio_dev);
> > +               } else if (chan->scan_index >= AMS_PS_SEQ_MAX)
> > +                       *val = readl(ams->pl_base + chan->address);
> > +               else
> > +                       *val = readl(ams->ps_base + chan->address);
> > +               mutex_unlock(&ams->lock);
> > +
> > +               return IIO_VAL_INT;
> > +       case IIO_CHAN_INFO_SCALE:
> > +               switch (chan->type) {
> > +               case IIO_VOLTAGE:
> > +                       switch (chan->address) {
> > +                       case AMS_SUPPLY1:
> > +                       case AMS_SUPPLY2:
> > +                       case AMS_SUPPLY3:
> > +                       case AMS_SUPPLY4:
> > +                               *val = AMS_SUPPLY_SCALE_3VOLT;
> > +                               break;
> > +                       case AMS_SUPPLY5:
> > +                       case AMS_SUPPLY6:
> > +                               if (chan->scan_index < AMS_PS_SEQ_MAX)
> > +                                       *val = AMS_SUPPLY_SCALE_6VOLT;
> > +                               else
> > +                                       *val = AMS_SUPPLY_SCALE_3VOLT;
> > +                               break;
> > +                       case AMS_SUPPLY7:
> > +                       case AMS_SUPPLY8:
> > +                               *val = AMS_SUPPLY_SCALE_6VOLT;
> > +                               break;
> > +                       case AMS_SUPPLY9:
> > +                       case AMS_SUPPLY10:
> > +                               if (chan->scan_index < AMS_PS_SEQ_MAX)
> > +                                       *val = AMS_SUPPLY_SCALE_3VOLT;
> > +                               else
> > +                                       *val = AMS_SUPPLY_SCALE_6VOLT;
> > +                               break;
> > +                       case AMS_VCC_PSPLL0:
> > +                       case AMS_VCC_PSPLL3:
> > +                       case AMS_VCCINT:
> > +                       case AMS_VCCBRAM:
> > +                       case AMS_VCCAUX:
> > +                       case AMS_PSDDRPLL:
> > +                       case AMS_PSINTFPDDR:
> > +                               *val = AMS_SUPPLY_SCALE_3VOLT;
> > +                               break;
> > +                       default:
> > +                               *val = AMS_SUPPLY_SCALE_1VOLT;
> > +                               break;
> > +                       }
> > +                       *val2 = AMS_SUPPLY_SCALE_DIV_BIT;
> > +                       return IIO_VAL_FRACTIONAL_LOG2;
> > +               case IIO_TEMP:
> > +                       *val = AMS_TEMP_SCALE;
> > +                       *val2 = AMS_TEMP_SCALE_DIV_BIT;
> > +                       return IIO_VAL_FRACTIONAL_LOG2;
> > +               default:
> > +                       return -EINVAL;
> > +               }
> > +       case IIO_CHAN_INFO_OFFSET:
> > +               /* Only the temperature channel has an offset */
> > +               *val = AMS_TEMP_OFFSET;
> > +               return IIO_VAL_INT;
> > +       }
> > +
> > +       return -EINVAL;
> > +}
> > +
> > +static int ams_get_alarm_offset(int scan_index, enum
> iio_event_direction dir)
> > +{
> > +       int offset = 0;
> > +
> > +       if (scan_index >= AMS_PS_SEQ_MAX)
> > +               scan_index -= AMS_PS_SEQ_MAX;
> > +
> > +       if (dir == IIO_EV_DIR_FALLING) {
> > +               if (scan_index < AMS_SEQ_SUPPLY7)
> > +                       offset = AMS_ALARM_THRESHOLD_OFF_10;
> > +               else
> > +                       offset = AMS_ALARM_THRESHOLD_OFF_20;
> > +       }
> > +
> > +       switch (scan_index) {
> > +       case AMS_SEQ_TEMP:
> > +               return AMS_ALARM_TEMP + offset;
> > +       case AMS_SEQ_SUPPLY1:
> > +               return AMS_ALARM_SUPPLY1 + offset;
> > +       case AMS_SEQ_SUPPLY2:
> > +               return AMS_ALARM_SUPPLY2 + offset;
> > +       case AMS_SEQ_SUPPLY3:
> > +               return AMS_ALARM_SUPPLY3 + offset;
> > +       case AMS_SEQ_SUPPLY4:
> > +               return AMS_ALARM_SUPPLY4 + offset;
> > +       case AMS_SEQ_SUPPLY5:
> > +               return AMS_ALARM_SUPPLY5 + offset;
> > +       case AMS_SEQ_SUPPLY6:
> > +               return AMS_ALARM_SUPPLY6 + offset;
> > +       case AMS_SEQ_SUPPLY7:
> > +               return AMS_ALARM_SUPPLY7 + offset;
> > +       case AMS_SEQ_SUPPLY8:
> > +               return AMS_ALARM_SUPPLY8 + offset;
> > +       case AMS_SEQ_SUPPLY9:
> > +               return AMS_ALARM_SUPPLY9 + offset;
> > +       case AMS_SEQ_SUPPLY10:
> > +               return AMS_ALARM_SUPPLY10 + offset;
> > +       case AMS_SEQ_VCCAMS:
> > +               return AMS_ALARM_VCCAMS + offset;
> > +       case AMS_SEQ_TEMP_REMOTE:
> > +               return AMS_ALARM_TEMP_REMOTE + offset;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct iio_chan_spec *ams_event_to_channel(
> > +               struct iio_dev *indio_dev, u32 event)
> > +{
> > +       int scan_index = 0, i;
> > +
> > +       if (event >= AMS_PL_ALARM_START) {
> > +               event -= AMS_PL_ALARM_START;
> > +               scan_index = AMS_PS_SEQ_MAX;
> > +       }
> > +
> > +       switch (event) {
> > +       case AMS_ALARM_BIT_TEMP:
> > +               scan_index += AMS_SEQ_TEMP;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY1:
> > +               scan_index += AMS_SEQ_SUPPLY1;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY2:
> > +               scan_index += AMS_SEQ_SUPPLY2;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY3:
> > +               scan_index += AMS_SEQ_SUPPLY3;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY4:
> > +               scan_index += AMS_SEQ_SUPPLY4;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY5:
> > +               scan_index += AMS_SEQ_SUPPLY5;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY6:
> > +               scan_index += AMS_SEQ_SUPPLY6;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY7:
> > +               scan_index += AMS_SEQ_SUPPLY7;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY8:
> > +               scan_index += AMS_SEQ_SUPPLY8;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY9:
> > +               scan_index += AMS_SEQ_SUPPLY9;
> > +               break;
> > +       case AMS_ALARM_BIT_SUPPLY10:
> > +               scan_index += AMS_SEQ_SUPPLY10;
> > +               break;
> > +       case AMS_ALARM_BIT_VCCAMS:
> > +               scan_index += AMS_SEQ_VCCAMS;
> > +               break;
> > +       case AMS_ALARM_BIT_TEMP_REMOTE:
> > +               scan_index += AMS_SEQ_TEMP_REMOTE;
> > +               break;
> > +       }
> > +
> > +       for (i = 0; i < indio_dev->num_channels; i++)
> > +               if (indio_dev->channels[i].scan_index == scan_index)
> > +                       break;
> > +
> > +       return &indio_dev->channels[i];
> > +}
> > +
> > +static int ams_get_alarm_mask(int scan_index)
> > +{
> > +       int bit = 0;
> > +
> > +       if (scan_index >= AMS_PS_SEQ_MAX) {
> > +               bit = AMS_PL_ALARM_START;
> > +               scan_index -= AMS_PS_SEQ_MAX;
> > +       }
> > +
> > +       switch (scan_index) {
> > +       case AMS_SEQ_TEMP:
> > +               return BIT(AMS_ALARM_BIT_TEMP + bit);
> 
> an alternative here would be to use a "map" here;
> something like:
> 
> struct ams_seq_bit_map {
>       int seq;
>       int bit;
>  };
> 
> then define a table:
> static struct ams_seq_bit_map ams_seq_bit_map[] = {
>  {  AMS_SEQ_TEMP,  AMS_ALARM_BIT_TEMP }
> };
> 
> then a use a search function:
> 
> for (i = 0; i < ARRAY_SIZE(ams_seq_bit_map); i++) {
>        if (ams_seq_bit_map[i].seq == scan_index)
>           return ams_seq_bit_map[i].bit;
> }
> 
> and vice-versa;
> 
> this makes things easier to extend; if a mapping is to be added, then
> the table gets a new entry and done;

This looks like a nice way to implement it.
But in this case, this is a very limited use case and there will be no need to extend this.
I will keep this in mind for the other driver that I am going to push.

> 
> > +       case AMS_SEQ_SUPPLY1:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY1 + bit);
> > +       case AMS_SEQ_SUPPLY2:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY2 + bit);
> > +       case AMS_SEQ_SUPPLY3:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY3 + bit);
> > +       case AMS_SEQ_SUPPLY4:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY4 + bit);
> > +       case AMS_SEQ_SUPPLY5:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY5 + bit);
> > +       case AMS_SEQ_SUPPLY6:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY6 + bit);
> > +       case AMS_SEQ_SUPPLY7:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY7 + bit);
> > +       case AMS_SEQ_SUPPLY8:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY8 + bit);
> > +       case AMS_SEQ_SUPPLY9:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY9 + bit);
> > +       case AMS_SEQ_SUPPLY10:
> > +               return BIT(AMS_ALARM_BIT_SUPPLY10 + bit);
> > +       case AMS_SEQ_VCCAMS:
> > +               return BIT(AMS_ALARM_BIT_VCCAMS + bit);
> > +       case AMS_SEQ_TEMP_REMOTE:
> > +               return BIT(AMS_ALARM_BIT_TEMP_REMOTE + bit);
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static int ams_read_event_config(struct iio_dev *indio_dev,
> > +                                const struct iio_chan_spec *chan,
> > +                                enum iio_event_type type,
> > +                                enum iio_event_direction dir)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +
> > +       return (ams->alarm_mask & ams_get_alarm_mask(chan-
> >scan_index)) ? 1 : 0;
> > +}
> > +
> > +static int ams_write_event_config(struct iio_dev *indio_dev,
> > +                                 const struct iio_chan_spec *chan,
> > +                                 enum iio_event_type type,
> > +                                 enum iio_event_direction dir,
> > +                                 int state)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       unsigned int alarm;
> > +
> > +       alarm = ams_get_alarm_mask(chan->scan_index);
> > +
> > +       mutex_lock(&ams->lock);
> > +
> > +       if (state)
> > +               ams->alarm_mask |= alarm;
> > +       else
> > +               ams->alarm_mask &= ~alarm;
> > +
> > +       ams_update_alarm(ams, ams->alarm_mask);
> > +
> > +       mutex_unlock(&ams->lock);
> > +
> > +       return 0;
> > +}
> > +
> > +static int ams_read_event_value(struct iio_dev *indio_dev,
> > +                               const struct iio_chan_spec *chan,
> > +                               enum iio_event_type type,
> > +                               enum iio_event_direction dir,
> > +                               enum iio_event_info info, int *val, int *val2)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       unsigned int offset = ams_get_alarm_offset(chan->scan_index, dir);
> > +
> > +       mutex_lock(&ams->lock);
> > +
> > +       if (chan->scan_index >= AMS_PS_SEQ_MAX)
> > +               *val = readl(ams->pl_base + offset);
> > +       else
> > +               *val = readl(ams->ps_base + offset);
> > +
> > +       mutex_unlock(&ams->lock);
> > +
> > +       return IIO_VAL_INT;
> > +}
> > +
> > +static int ams_write_event_value(struct iio_dev *indio_dev,
> > +                                const struct iio_chan_spec *chan,
> > +                                enum iio_event_type type,
> > +                                enum iio_event_direction dir,
> > +                                enum iio_event_info info, int val, int val2)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       unsigned int offset;
> > +
> > +       mutex_lock(&ams->lock);
> > +
> > +       /* Set temperature channel threshold to direct threshold */
> > +       if (chan->type == IIO_TEMP) {
> > +               offset = ams_get_alarm_offset(chan->scan_index,
> > +                                             IIO_EV_DIR_FALLING);
> > +
> > +               if (chan->scan_index >= AMS_PS_SEQ_MAX)
> > +                       ams_pl_update_reg(ams, offset,
> > +                                           AMS_ALARM_THR_DIRECT_MASK,
> > +                                           AMS_ALARM_THR_DIRECT_MASK);
> > +               else
> > +                       ams_ps_update_reg(ams, offset,
> > +                                         AMS_ALARM_THR_DIRECT_MASK,
> > +                                         AMS_ALARM_THR_DIRECT_MASK);
> > +       }
> > +
> > +       offset = ams_get_alarm_offset(chan->scan_index, dir);
> > +       if (chan->scan_index >= AMS_PS_SEQ_MAX)
> > +               writel(val, ams->pl_base + offset);
> > +       else
> > +               writel(val, ams->ps_base + offset);
> > +
> > +       mutex_unlock(&ams->lock);
> > +
> > +       return 0;
> > +}
> > +
> > +static void ams_handle_event(struct iio_dev *indio_dev, u32 event)
> > +{
> > +       const struct iio_chan_spec *chan;
> > +
> > +       chan = ams_event_to_channel(indio_dev, event);
> > +
> > +       if (chan->type == IIO_TEMP) {
> > +               /*
> > +                * The temperature channel only supports over-temperature
> > +                * events
> > +                */
> > +               iio_push_event(indio_dev,
> > +                              IIO_UNMOD_EVENT_CODE(chan->type, chan->channel,
> > +                                                   IIO_EV_TYPE_THRESH,
> > +                                                   IIO_EV_DIR_RISING),
> > +                       iio_get_time_ns(indio_dev));
> > +       } else {
> > +               /*
> > +                * For other channels we don't know whether it is a upper or
> > +                * lower threshold event. Userspace will have to check the
> > +                * channel value if it wants to know.
> > +                */
> > +               iio_push_event(indio_dev,
> > +                              IIO_UNMOD_EVENT_CODE(chan->type, chan->channel,
> > +                                                   IIO_EV_TYPE_THRESH,
> > +                                                   IIO_EV_DIR_EITHER),
> > +                       iio_get_time_ns(indio_dev));
> > +       }
> > +}
> > +
> > +static void ams_handle_events(struct iio_dev *indio_dev, unsigned long
> events)
> > +{
> > +       unsigned int bit;
> > +
> > +       for_each_set_bit(bit, &events, AMS_NO_OF_ALARMS)
> > +               ams_handle_event(indio_dev, bit);
> > +}
> > +
> > +/**
> > + * ams_unmask_worker - ams alarm interrupt unmask worker
> > + * @work :             work to be done
> > + *
> > + * The ZynqMP threshold interrupts are level sensitive. Since we can't
> make the
> > + * threshold condition go way from within the interrupt handler, this
> means as
> > + * soon as a threshold condition is present we would enter the interrupt
> handler
> > + * again and again. To work around this we mask all active threshold
> interrupts
> > + * in the interrupt handler and start a timer. In this timer we poll the
> > + * interrupt status and only if the interrupt is inactive we unmask it again.
> > + */
> > +static void ams_unmask_worker(struct work_struct *work)
> > +{
> > +       struct ams *ams = container_of(work, struct ams,
> ams_unmask_work.work);
> > +       unsigned int status, unmask;
> > +
> > +       mutex_lock(&ams->lock);
> > +
> > +       status = readl(ams->base + AMS_ISR_0);
> > +
> > +       /* Clear those bits which are not active anymore */
> > +       unmask = (ams->masked_alarm ^ status) & ams->masked_alarm;
> > +
> > +       /* clear status of disabled alarm */
> > +       unmask |= ams->intr_mask;
> > +
> > +       ams->masked_alarm &= status;
> > +
> > +       /* Also clear those which are masked out anyway */
> > +       ams->masked_alarm &= ~ams->intr_mask;
> > +
> > +       /* Clear the interrupts before we unmask them */
> > +       writel(unmask, ams->base + AMS_ISR_0);
> > +
> > +       ams_update_intrmask(ams, 0, 0);
> > +
> > +       mutex_unlock(&ams->lock);
> > +
> > +       /* if still pending some alarm re-trigger the timer */
> > +       if (ams->masked_alarm)
> > +               schedule_delayed_work(&ams->ams_unmask_work,
> > +                                     msecs_to_jiffies(AMS_UNMASK_TIMEOUT_MS));
> > +}
> > +
> > +static irqreturn_t ams_irq(int irq, void *data)
> > +{
> > +       struct iio_dev *indio_dev = data;
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       u32 isr0;
> > +
> > +       isr0 = readl(ams->base + AMS_ISR_0);
> > +
> > +       /* only process alarms that are not masked */
> > +       isr0 &= ~((ams->intr_mask & AMS_ISR0_ALARM_MASK) | ams-
> >masked_alarm);
> > +
> > +       if (!isr0)
> > +               return IRQ_NONE;
> > +
> > +       /* clear interrupt */
> > +       writel(isr0, ams->base + AMS_ISR_0);
> > +
> > +       /* Mask the alarm interrupts until cleared */
> > +       ams->masked_alarm |= isr0;
> > +       ams_update_intrmask(ams, 0, 0);
> > +
> > +       ams_handle_events(indio_dev, isr0);
> > +
> > +       schedule_delayed_work(&ams->ams_unmask_work,
> > +                             msecs_to_jiffies(AMS_UNMASK_TIMEOUT_MS));
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static const struct iio_event_spec ams_temp_events[] = {
> > +       {
> > +               .type = IIO_EV_TYPE_THRESH,
> > +               .dir = IIO_EV_DIR_RISING,
> > +               .mask_separate = BIT(IIO_EV_INFO_ENABLE) |
> > +                               BIT(IIO_EV_INFO_VALUE),
> > +       },
> > +};
> > +
> > +static const struct iio_event_spec ams_voltage_events[] = {
> > +       {
> > +               .type = IIO_EV_TYPE_THRESH,
> > +               .dir = IIO_EV_DIR_RISING,
> > +               .mask_separate = BIT(IIO_EV_INFO_VALUE),
> > +       },
> > +       {
> > +               .type = IIO_EV_TYPE_THRESH,
> > +               .dir = IIO_EV_DIR_FALLING,
> > +               .mask_separate = BIT(IIO_EV_INFO_VALUE),
> > +       },
> > +       {
> > +               .type = IIO_EV_TYPE_THRESH,
> > +               .dir = IIO_EV_DIR_EITHER,
> > +               .mask_separate = BIT(IIO_EV_INFO_ENABLE),
> > +       },
> > +};
> > +
> > +static const struct iio_chan_spec ams_ps_channels[] = {
> > +       AMS_PS_CHAN_TEMP(AMS_SEQ_TEMP, AMS_TEMP),
> > +       AMS_PS_CHAN_TEMP(AMS_SEQ_TEMP_REMOTE,
> AMS_TEMP_REMOTE),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY1, AMS_SUPPLY1),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY2, AMS_SUPPLY2),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY3, AMS_SUPPLY3),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY4, AMS_SUPPLY4),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY5, AMS_SUPPLY5),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY6, AMS_SUPPLY6),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY7, AMS_SUPPLY7),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY8, AMS_SUPPLY8),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY9, AMS_SUPPLY9),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY10, AMS_SUPPLY10),
> > +       AMS_PS_CHAN_VOLTAGE(AMS_SEQ_VCCAMS, AMS_VCCAMS),
> > +};
> > +
> > +static const struct iio_chan_spec ams_pl_channels[] = {
> > +       AMS_PL_CHAN_TEMP(AMS_SEQ_TEMP, AMS_TEMP),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY1, AMS_SUPPLY1, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY2, AMS_SUPPLY2, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VREFP, AMS_VREFP, false),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VREFN, AMS_VREFN, false),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY3, AMS_SUPPLY3, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY4, AMS_SUPPLY4, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY5, AMS_SUPPLY5, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY6, AMS_SUPPLY6, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VCCAMS, AMS_VCCAMS, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VP_VN, AMS_VP_VN, false),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY7, AMS_SUPPLY7, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY8, AMS_SUPPLY8, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY9, AMS_SUPPLY9, true),
> > +       AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY10, AMS_SUPPLY10,
> true),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(0),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(1),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(2),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(3),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(4),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(5),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(6),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(7),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(8),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(9),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(10),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(11),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(12),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(13),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(14),
> > +       AMS_PL_AUX_CHAN_VOLTAGE(15),
> > +};
> > +
> > +static const struct iio_chan_spec ams_ctrl_channels[] = {
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCC_PSPLL,
> AMS_VCC_PSPLL0),
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCC_PSBATT,
> AMS_VCC_PSPLL3),
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCCINT, AMS_VCCINT),
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCCBRAM, AMS_VCCBRAM),
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCCAUX, AMS_VCCAUX),
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_PSDDRPLL, AMS_PSDDRPLL),
> > +       AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_INTDDR, AMS_PSINTFPDDR),
> > +};
> > +
> > +static int ams_get_ext_chan(struct device_node *chan_node,
> > +                           struct iio_chan_spec *channels, int num_channels)
> > +{
> > +       struct device_node *child;
> > +       unsigned int reg;
> > +       int ret;
> > +
> > +       for_each_child_of_node(chan_node, child) {
> > +               ret = of_property_read_u32(child, "reg", &reg);
> > +               if (ret || reg > (AMS_PL_MAX_EXT_CHANNEL + 30))
> > +                       continue;
> > +
> > +               memcpy(&channels[num_channels], &ams_pl_channels[reg +
> > +                      AMS_PL_MAX_FIXED_CHANNEL - 30], sizeof(*channels));
> > +
> > +               if (of_property_read_bool(child,
> > +                                         "xlnx,bipolar"))
> > +                       channels[num_channels].scan_type.sign = 's';
> > +
> > +               num_channels++;
> > +       }
> > +
> > +       return num_channels;
> > +}
> > +
> > +static int ams_init_module(struct iio_dev *indio_dev, struct device_node
> *np,
> > +                          struct iio_chan_spec *channels)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       struct device_node *chan_node;
> > +       int num_channels = 0;
> > +
> > +       if (of_device_is_compatible(np, "xlnx,zynqmp-ams-ps")) {
> > +               ams->ps_base = of_iomap(np, 0);
> > +               if (!ams->ps_base)
> > +                       return -ENXIO;
> > +
> > +               /* add PS channels to iio device channels */
> > +               memcpy(channels + num_channels, ams_ps_channels,
> > +                      sizeof(ams_ps_channels));
> > +               num_channels += ARRAY_SIZE(ams_ps_channels);
> > +       } else if (of_device_is_compatible(np, "xlnx,zynqmp-ams-pl")) {
> > +               ams->pl_base = of_iomap(np, 0);
> > +               if (!ams->pl_base)
> > +                       return -ENXIO;
> > +
> > +               /* Copy only first 10 fix channels */
> > +               memcpy(channels + num_channels, ams_pl_channels,
> > +                      AMS_PL_MAX_FIXED_CHANNEL * sizeof(*channels));
> > +               num_channels += AMS_PL_MAX_FIXED_CHANNEL;
> > +
> > +               chan_node = of_get_child_by_name(np, "xlnx,ext-channels");
> > +               if (chan_node)
> > +                       num_channels = ams_get_ext_chan(chan_node, channels,
> > +                                                       num_channels);
> > +
> > +               of_node_put(chan_node);
> > +       } else if (of_device_is_compatible(np, "xlnx,zynqmp-ams")) {
> > +               /* add AMS channels to iio device channels */
> > +               memcpy(channels + num_channels, ams_ctrl_channels,
> > +                               sizeof(ams_ctrl_channels));
> > +               num_channels += ARRAY_SIZE(ams_ctrl_channels);
> > +       } else {
> > +               return -EINVAL;
> > +       }
> > +
> > +       return num_channels;
> > +}
> > +
> > +static int ams_parse_dt(struct iio_dev *indio_dev, struct platform_device
> *pdev)
> > +{
> > +       struct ams *ams = iio_priv(indio_dev);
> > +       struct iio_chan_spec *ams_channels, *dev_channels;
> > +       struct device_node *child_node = NULL, *np = pdev->dev.of_node;
> > +       int ret, vol_ch_cnt = 0, temp_ch_cnt = 0, i, rising_off, falling_off;
> > +       unsigned int num_channels = 0;
> > +
> > +       /* Initialize buffer for channel specification */
> > +       ams_channels = kzalloc(sizeof(ams_ps_channels) +
> > +                              sizeof(ams_pl_channels) +
> > +                              sizeof(ams_ctrl_channels), GFP_KERNEL);
> > +       if (!ams_channels)
> > +               return -ENOMEM;
> 
> maybe an idea here, would be to just do `devm_kzalloc()` here and use
> a single "dev_channels" variable;
> in the end this "indio_dev->num_channels = num_channels" assignment
> would limit the number of IIO channels to what would actually be used;
> 
> i'll admit, this would allocate a bit more memory than needed;
> technically the wasted space wouldn't be too much; and would be within
> acceptable limits;
> 
> but if the intent is to allocate exactly the amount needed, then the
> "sprintf()" technique can be used here;
> i.e.:
> 
> ret = sprintf(NULL, "format_string")
> if (ret < 0)
>    return ret;
> 
> s = malloc(ret)
> 
> ret = sprintf(s, "format_string")
> 
> so, essentially, a function would be implemented that can take a NULL
> channel pointer, which would return the number of channels that would
> be configured if the pointer would be non-NULL;
> 
I think this would make it a bit too complicated than what it is?

> 
> 
> > +
> > +       if (of_device_is_available(np)) {
> > +               ret = ams_init_module(indio_dev, np, ams_channels);
> > +               if (ret < 0)
> > +                       goto err;
> > +
> > +               num_channels += ret;
> > +       }
> > +
> > +       for_each_child_of_node(np, child_node) {
> > +               if (of_device_is_available(child_node)) {
> > +                       ret = ams_init_module(indio_dev, child_node,
> > +                                             ams_channels + num_channels);
> > +                       if (ret < 0)
> > +                               goto err;
> > +
> > +                       num_channels += ret;
> > +               }
> > +       }
> > +
> > +       for (i = 0; i < num_channels; i++) {
> > +               if (ams_channels[i].type == IIO_VOLTAGE)
> > +                       ams_channels[i].channel = vol_ch_cnt++;
> > +               else
> > +                       ams_channels[i].channel = temp_ch_cnt++;
> > +
> > +               if (ams_channels[i].scan_index < (AMS_PS_SEQ_MAX * 3)) {
> > +                       /* set threshold to max and min for each channel */
> > +                       falling_off = ams_get_alarm_offset(
> > +                                       ams_channels[i].scan_index,
> > +                                       IIO_EV_DIR_FALLING);
> > +                       rising_off = ams_get_alarm_offset(
> > +                                       ams_channels[i].scan_index,
> > +                                       IIO_EV_DIR_RISING);
> > +                       if (ams_channels[i].scan_index >= AMS_PS_SEQ_MAX) {
> > +                               writel(AMS_ALARM_THR_MIN,
> > +                                               ams->pl_base + falling_off);
> > +                               writel(AMS_ALARM_THR_MAX,
> > +                                               ams->pl_base + rising_off);
> > +                       } else {
> > +                               writel(AMS_ALARM_THR_MIN,
> > +                                               ams->ps_base + falling_off);
> > +                               writel(AMS_ALARM_THR_MAX,
> > +                                               ams->ps_base + rising_off);
> > +                       }
> > +               }
> > +       }
> > +
> > +       dev_channels = devm_kzalloc(&pdev->dev, sizeof(*dev_channels) *
> > +                                   num_channels, GFP_KERNEL);
> > +       if (!dev_channels) {
> > +               ret = -ENOMEM;
> > +               goto err;
> > +       }
> > +
> > +       memcpy(dev_channels, ams_channels,
> > +              sizeof(*ams_channels) * num_channels);
> > +       indio_dev->channels = dev_channels;
> > +       indio_dev->num_channels = num_channels;
> > +
> > +       ret = 0;
> > +err:
> > +       kfree(ams_channels);
> > +
> > +       return ret;
> > +}
> > +
> > +static const struct iio_info iio_ams_info = {
> > +       .read_raw = &ams_read_raw,
> > +       .read_event_config = &ams_read_event_config,
> > +       .write_event_config = &ams_write_event_config,
> > +       .read_event_value = &ams_read_event_value,
> > +       .write_event_value = &ams_write_event_value,
> > +};
> > +
> > +static const struct of_device_id ams_of_match_table[] = {
> > +       { .compatible = "xlnx,zynqmp-ams" },
> > +       { }
> > +};
> > +MODULE_DEVICE_TABLE(of, ams_of_match_table);
> > +
> > +static int ams_probe(struct platform_device *pdev)
> > +{
> > +       struct iio_dev *indio_dev;
> > +       struct ams *ams;
> > +       struct resource *res;
> > +       int ret;
> > +
> > +       if (!pdev->dev.of_node)
> > +               return -ENODEV;
> > +
> > +       indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*ams));
> > +       if (!indio_dev)
> > +               return -ENOMEM;
> > +
> > +       ams = iio_priv(indio_dev);
> > +       mutex_init(&ams->lock);
> > +
> > +       indio_dev->dev.parent = &pdev->dev;
> > +       indio_dev->dev.of_node = pdev->dev.of_node;
> 
> these 2 assignments can be removed;
> they are assigned in iio_device_alloc() and  iio_device_register()
> 
> > +       indio_dev->name = "xilinx-ams";
> > +
> > +       indio_dev->info = &iio_ams_info;
> > +       indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> > +       res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> "ams-base");
> > +       ams->base = devm_ioremap_resource(&pdev->dev, res);
> > +       if (IS_ERR(ams->base))
> > +               return PTR_ERR(ams->base);
> > +
> > +       ams->clk = devm_clk_get(&pdev->dev, NULL);
> > +       if (IS_ERR(ams->clk))
> > +               return PTR_ERR(ams->clk);
> > +       clk_prepare_enable(ams->clk);
> 
> [1]
> a better idea is to use a devm_add_action_or_reset() hook to call
> clk_disable_unprepare() here

Agreed. Will add this in the next patch series.

> 
> > +
> > +       INIT_DELAYED_WORK(&ams->ams_unmask_work,
> ams_unmask_worker);
> 
> [2]
> a devm_add_action_or_reset() can be registered/setup here to call
> cancel_delayed_work()

Agreed. Will add this in the next patch series.

> 
> > +
> > +       ret = ams_init_device(ams);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "failed to initialize AMS\n");
> > +               goto err_probe;
> > +       }
> > +
> > +       ret = ams_parse_dt(indio_dev, pdev);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "failure in parsing DT\n");
> > +               goto err_probe;
> > +       }
> > +
> > +       ams_enable_channel_sequence(indio_dev);
> > +
> > +       ams->irq = platform_get_irq_byname(pdev, "ams-irq");
> > +       ret = request_irq(ams->irq, &ams_irq, 0, "ams-irq", indio_dev);
> 
> [3]
> devm_request_irq() can be used here

Agreed. Will add this in the next patch series.

> 
> > +       if (ret < 0) {
> > +               dev_err(&pdev->dev, "failed to register interrupt\n");
> > +               goto err_probe;
> > +       }
> > +
> > +       platform_set_drvdata(pdev, indio_dev);
> > +
> > +       ret = iio_device_register(indio_dev);
> > +       if (ret)
> > +               goto err_irq_free;
> 
> [4]
> if [1],[2] and [3] is being implemented, all "goto err" paths can be
> direct returns
> and this can be   "return devm_iio_device_register(&pdev->dev,
> indio_dev);"

Agreed. Will add this in the next patch series.
> 
> > +
> > +       return 0;
> > +
> > +err_irq_free:
> > +       free_irq(ams->irq, indio_dev);
> > +
> > +err_probe:
> > +       cancel_delayed_work(&ams->ams_unmask_work);
> > +       clk_disable_unprepare(ams->clk);
> > +
> > +       return ret;
> > +}
> > +
> > +static int ams_remove(struct platform_device *pdev)
> 
> following [4], if that is implemented, the ams_remove() hook can be
> removed altogether;
> 

I would still need this to unregister the device.

> > +{
> > +       struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > +       struct ams *ams = iio_priv(indio_dev);
> > +
> > +       iio_device_unregister(indio_dev);
> > +       free_irq(ams->irq, indio_dev);
> > +       cancel_delayed_work(&ams->ams_unmask_work);
> > +       clk_disable_unprepare(ams->clk);
> > +
> > +       return 0;
> > +}
> > +
> > +static int __maybe_unused ams_suspend(struct device *dev)
> > +{
> > +       struct ams *ams = iio_priv(dev_get_drvdata(dev));
> > +
> > +       clk_disable_unprepare(ams->clk);
> > +
> > +       return 0;
> > +}
> > +
> > +static int __maybe_unused ams_resume(struct device *dev)
> > +{
> > +       struct ams *ams = iio_priv(dev_get_drvdata(dev));
> > +
> > +       clk_prepare_enable(ams->clk);
> > +
> > +       return 0;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(ams_pm_ops, ams_suspend, ams_resume);
> > +
> > +static struct platform_driver ams_driver = {
> > +       .probe = ams_probe,
> > +       .remove = ams_remove,
> > +       .driver = {
> > +               .name = "xilinx-ams",
> > +               .pm = &ams_pm_ops,
> > +               .of_match_table = ams_of_match_table,
> > +       },
> > +};
> > +module_platform_driver(ams_driver);
> > +
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_AUTHOR("Xilinx, Inc.");
> > --
> > 2.17.1
> >

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