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Date:	Tue, 27 May 2014 00:33:30 +0200
From:	Hartmut Knaack <knaack.h@....de>
To:	trem <tremyfr@...oo.fr>
CC:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	armadeus-forum@...ts.sourceforge.net, jic23@...nel.org
Subject: Re: [PATCH v2] iio: add support of the max1027

trem schrieb:
> Hi Hartmut,
>
> First, thanks a lot for this feedback, I really appreciate it.
>
>
> On 26/05/14 00:52, Hartmut Knaack wrote:
>> Philippe Reynes schrieb:
>>> This driver add partial support of the
>>> maxim 1027/1029/1031. Differential mode is not
>>> supported.
>>>
>>> It was tested on armadeus apf27 board.
>>>
>>> Signed-off-by: Philippe Reynes<tremyfr@...oo.fr>
>>> ---
>>>   .../devicetree/bindings/iio/adc/max1027-adc.txt    |   21 +
>>>   drivers/staging/iio/adc/Kconfig                    |    9 +
>>>   drivers/staging/iio/adc/Makefile                   |    1 +
>>>   drivers/staging/iio/adc/max1027.c                  |  553 ++++++++++++++++++++
>>>   4 files changed, 584 insertions(+), 0 deletions(-)
>>>   create mode 100644 Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
>>>   create mode 100644 drivers/staging/iio/adc/max1027.c
>>>
>>> Changelog:
>>> v2: (thanks Hartmut Knaack and Jonathan Cameron for the feedback)
>>> - really use devm_*
>>> - use demux magic
>>> - use spi_read and spi_write (instead of spi_sync)
>>> - use define for register (instead of hardcoded value)
>>>
>>> diff --git a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
>>> new file mode 100644
>>> index 0000000..2e8b9f3
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
>>> @@ -0,0 +1,21 @@
>>> +* Maxim 1027/1029/1031 Analog to Digital Converter (ADC)
>>> +
>>> +Required properties:
>>> +  - compatible: Should be "maxim,max1027" or "maxim,max1029" or "maxim,max1031"
>>> +  - reg: Should contain the ADC SPI address
>>> +  - interrupt-parent: the phandle for the gpio controller
>>> +  - interrupts: (gpio) interrupt to which the chip is connected
>>> +
>>> +Example:
>>> +adc@0 {
>>> +	compatible = "maxim,max1027";
>>> +	reg =<0>;
>>> +	interrupt-parent =<&gpio5>;
>>> +	interrupts =<15 IRQ_TYPE_EDGE_RISING>;
>>> +	pinctrl-names = "default";
>>> +	pinctrl-0 =<&pinctrl_max1027>;
>>> +	/* SPI mode = 0 */
>>> +	spi-cpol =<0>;
>>> +	spi-cpha =<0>;
>>> +	spi-max-frequency =<1000000>;
>>> +};
>>> diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
>>> index 3633298..12a78eb 100644
>>> --- a/drivers/staging/iio/adc/Kconfig
>>> +++ b/drivers/staging/iio/adc/Kconfig
>>> @@ -112,6 +112,15 @@ config LPC32XX_ADC
>>>   	  activate only one via device tree selection.  Provides direct access
>>>   	  via sysfs.
>>>
>>> +config MAX1027
>>> +	tristate "Maxim max1027 ADC driver"
>>> +	depends on SPI
>>> +	select IIO_BUFFER
>>> +	select IIO_TRIGGERED_BUFFER
>>> +	help
>>> +	  Say yes here to build support for Maxim SPI ADC models
>>> +	  max1027, max1029 and max1031.
>>> +
>>>   config MXS_LRADC
>>>   	tristate "Freescale i.MX23/i.MX28 LRADC"
>>>   	depends on ARCH_MXS || COMPILE_TEST
>>> diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
>>> index 3e9fb14..22fbd0c 100644
>>> --- a/drivers/staging/iio/adc/Makefile
>>> +++ b/drivers/staging/iio/adc/Makefile
>>> @@ -18,5 +18,6 @@ obj-$(CONFIG_AD7816) += ad7816.o
>>>   obj-$(CONFIG_AD7192) += ad7192.o
>>>   obj-$(CONFIG_AD7280) += ad7280a.o
>>>   obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
>>> +obj-$(CONFIG_MAX1027) += max1027.o
>>>   obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
>>>   obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
>>> diff --git a/drivers/staging/iio/adc/max1027.c b/drivers/staging/iio/adc/max1027.c
>>> new file mode 100644
>>> index 0000000..c2e5936
>>> --- /dev/null
>>> +++ b/drivers/staging/iio/adc/max1027.c
>>> @@ -0,0 +1,553 @@
>>> + /*
>>> +  * iio/adc/max1027.c
>>> +  * Copyright (C) 2014 Philippe Reynes
>>> +  *
>>> +  * based on linux/drivers/iio/ad7923.c
>>> +  * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
>>> +  * Copyright 2012 CS Systemes d'Information
>>> +  *
>>> +  * This program is free software; you can redistribute it and/or modify
>>> +  * it under the terms of the GNU General Public License version 2 as
>>> +  * published by the Free Software Foundation.
>>> +  *
>>> +  * max1027.c
>>> +  *
>>> +  * Partial support for max1027 and similar chips.
>>> +  */
>>> +
>>> +#include<linux/kernel.h>
>>> +#include<linux/spi/spi.h>
>>> +#include<linux/module.h>
>>> +#include<linux/interrupt.h>
>>> +#include<linux/mutex.h>
>>> +#include<linux/of.h>
>>> +#include<linux/of_gpio.h>
>>> +#include<linux/platform_device.h>
>>> +#include<linux/delay.h>
>>> +#include<linux/gpio.h>
>>> +
>>> +#include<linux/iio/iio.h>
>>> +#include<linux/iio/buffer.h>
>>> +#include<linux/iio/trigger.h>
>>> +#include<linux/iio/trigger_consumer.h>
>>> +#include<linux/iio/triggered_buffer.h>
>>> +
>>> +#define MAX1027_CONV_REG  0x80
>>> +#define MAX1027_SETUP_REG 0x40
>>> +#define MAX1027_AVG_REG   0x20
>>> +#define MAX1027_RST_REG   0x10
>>> +
>>> +/* conversion register */
>>> +#define MAX1027_TEMP      0x01
>>> +#define MAX1027_SCAN_0_N  (0x00<<  1)
>>> +#define MAX1027_SCAN_N_M  (0x01<<  1)
>>> +#define MAX1027_SCAN_N    (0x02<<  1)
>>> +#define MAX1027_NOSCAN    (0x03<<  1)
>>> +#define MAX1027_CHAN(n)   ((n)<<  3)
>>> +
>>> +/* setup register */
>>> +#define MAX1027_UNIPOLAR  0x02
>>> +#define MAX1027_BIPOLAR   0x03
>>> +#define MAX1027_REF_MODE0 (0x00<<  2)
>>> +#define MAX1027_REF_MODE1 (0x01<<  2)
>>> +#define MAX1027_REF_MODE2 (0x02<<  2)
>>> +#define MAX1027_REF_MODE3 (0x03<<  2)
>>> +#define MAX1027_CKS_MODE0 (0x00<<  4)
>>> +#define MAX1027_CKS_MODE1 (0x01<<  4)
>>> +#define MAX1027_CKS_MODE2 (0x02<<  4)
>>> +#define MAX1027_CKS_MODE3 (0x03<<  4)
>>> +
>>> +/* averaging register */
>>> +#define MAX1027_NSCAN_4   0x00
>>> +#define MAX1027_NSCAN_8   0x01
>>> +#define MAX1027_NSCAN_12  0x02
>>> +#define MAX1027_NSCAN_16  0x03
>>> +#define MAX1027_NAVG_4    (0x00<<  2)
>>> +#define MAX1027_NAVG_8    (0x01<<  2)
>>> +#define MAX1027_NAVG_12   (0x02<<  2)
>>> +#define MAX1027_NAVG_16   (0x03<<  2)
>> According to my datasheet (revision 5) [http://datasheets.maximintegrated.com/en/ds/MAX1027-MAX1031.pdf], there is no NAVG_12, but NAVG_16 (0x02<<  2) and NAVG_32 (0x03<<  2).
> My datasheet has the same value, I'll fix this mistake in v3.
>
>>> +#define MAX1027_AVG_EN    (0x01<<  4)
>>> +
>>> +enum max1027_id {
>>> +	max1027,
>>> +	max1029,
>>> +	max1031,
>>> +};
>>> +
>>> +static const struct spi_device_id max1027_id[] = {
>>> +	{"max1027", max1027},
>>> +	{"max1029", max1029},
>>> +	{"max1031", max1031},
>>> +	{}
>>> +};
>>> +MODULE_DEVICE_TABLE(spi, max1027_id);
>>> +
>>> +#ifdef CONFIG_OF
>>> +static const struct of_device_id max1027_adc_dt_ids[] = {
>>> +	{ .compatible = "maxim,max1027" },
>>> +	{ .compatible = "maxim,max1029" },
>>> +	{ .compatible = "maxim,max1031" },
>>> +	{},
>>> +};
>>> +MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
>>> +#endif
>>> +
>>> +#define MAX1027_V_CHAN(index)						\
>>> +	{								\
>>> +		.type = IIO_VOLTAGE,					\
>>> +		.indexed = 1,						\
>>> +		.channel = index,					\
>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>>> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
>>> +		.address = index,					\
>>> +		.scan_index = index+1,					\
>>> +		.scan_type = {						\
>>> +			.sign = 'u',					\
>>> +			.realbits = 10,					\
>>> +			.storagebits = 16,				\
>>> +			.shift = 2,					\
>>> +			.endianness = IIO_BE,				\
>>> +		},							\
>>> +	}
>>> +
>>> +#define MAX1027_T_CHAN(index)						\
>>> +	{								\
>>> +		.type = IIO_TEMP,					\
>>> +		.indexed = 0,						\
>>> +		.channel = index,					\
>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>>> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
>>> +		.address = index,					\
>>> +		.scan_index = index,					\
>>> +		.scan_type = {						\
>>> +			.sign = 'u',					\
>>> +			.realbits = 12,					\
>>> +			.storagebits = 16,				\
>>> +			.endianness = IIO_BE,				\
>>> +		},							\
>>> +	}
>>> +
>>> +static const struct iio_chan_spec max1027_channels[] = {
>>> +	MAX1027_T_CHAN(0),
>>> +	MAX1027_V_CHAN(0),
>>> +	MAX1027_V_CHAN(1),
>>> +	MAX1027_V_CHAN(2),
>>> +	MAX1027_V_CHAN(3),
>>> +	MAX1027_V_CHAN(4),
>>> +	MAX1027_V_CHAN(5),
>>> +	MAX1027_V_CHAN(6),
>>> +	MAX1027_V_CHAN(7)
>>> +};
>>> +
>>> +static const struct iio_chan_spec max1029_channels[] = {
>>> +	MAX1027_T_CHAN(0),
>>> +	MAX1027_V_CHAN(0),
>>> +	MAX1027_V_CHAN(1),
>>> +	MAX1027_V_CHAN(2),
>>> +	MAX1027_V_CHAN(3),
>>> +	MAX1027_V_CHAN(4),
>>> +	MAX1027_V_CHAN(5),
>>> +	MAX1027_V_CHAN(6),
>>> +	MAX1027_V_CHAN(7),
>>> +	MAX1027_V_CHAN(8),
>>> +	MAX1027_V_CHAN(9),
>>> +	MAX1027_V_CHAN(10),
>>> +	MAX1027_V_CHAN(11)
>>> +};
>>> +
>>> +static const struct iio_chan_spec max1031_channels[] = {
>>> +	MAX1027_T_CHAN(0),
>>> +	MAX1027_V_CHAN(0),
>>> +	MAX1027_V_CHAN(1),
>>> +	MAX1027_V_CHAN(2),
>>> +	MAX1027_V_CHAN(3),
>>> +	MAX1027_V_CHAN(4),
>>> +	MAX1027_V_CHAN(5),
>>> +	MAX1027_V_CHAN(6),
>>> +	MAX1027_V_CHAN(7),
>>> +	MAX1027_V_CHAN(8),
>>> +	MAX1027_V_CHAN(9),
>>> +	MAX1027_V_CHAN(10),
>>> +	MAX1027_V_CHAN(11),
>>> +	MAX1027_V_CHAN(12),
>>> +	MAX1027_V_CHAN(13),
>>> +	MAX1027_V_CHAN(14),
>>> +	MAX1027_V_CHAN(15)
>>> +};
>>> +
>>> +static unsigned long max1027_available_scan_masks[] = {
>>> +	0x00ff,
>>> +	0x0000,
>>> +};
>>> +
>>> +static unsigned long max1029_available_scan_masks[] = {
>>> +	0x0fff,
>>> +	0x0000,
>>> +};
>>> +
>>> +static unsigned long max1031_available_scan_masks[] = {
>>> +	0xffff,
>>> +	0x0000,
>>> +};
>>> +
>>> +struct max1027_chip_info {
>>> +	const struct iio_chan_spec *channels;
>>> +	unsigned int num_channels;
>>> +	unsigned long *available_scan_masks;
>>> +};
>>> +
>>> +static const struct max1027_chip_info max1027_chip_info_tbl[] = {
>>> +	[max1027] = {
>>> +		.channels = max1027_channels,
>>> +		.num_channels = ARRAY_SIZE(max1027_channels),
>>> +		.available_scan_masks = max1027_available_scan_masks,
>>> +	},
>>> +	[max1029] = {
>>> +		.channels = max1029_channels,
>>> +		.num_channels = ARRAY_SIZE(max1029_channels),
>>> +		.available_scan_masks = max1029_available_scan_masks,
>>> +	},
>>> +	[max1031] = {
>>> +		.channels = max1031_channels,
>>> +		.num_channels = ARRAY_SIZE(max1031_channels),
>>> +		.available_scan_masks = max1031_available_scan_masks,
>>> +	},
>>> +};
>>> +
>>> +struct max1027_state {
>>> +	struct max1027_chip_info	*info;
>>> +	struct spi_device		*spi;
>>> +	struct iio_trigger		*trig;
>>> +	unsigned short			*buffer;
>> Better use u16 for buffer?
> Yes, fixed in v3.
>
>>> +};
>>> +
>>> +static int max1027_write_register(struct max1027_state *st, unsigned char reg)
>>> +{
>>> +	int ret;
>>> +
>>> +	pr_debug("%s(st = 0x%p, reg = 0x%02x)\n", __func__, st, reg);
>>> +
>>> +	ret = spi_write(st->spi, (void *)&reg, 1);
>>> +	if (ret<  0)
>>> +		pr_err("can't write register\n");
>>> +
>>> +	return ret;
>>> +}
>> As Jonathan pointed out, better get rid of those debug wrapper functions. Otherwise, think about using typedefs like u8 for 8 bit registers.
> I've remove this function (and max10247_read_value) in v3.
>
>>> +
>>> +static int max1027_read_value(struct max1027_state *st, int len)
>>> +{
>>> +	int ret;
>>> +
>>> +	pr_debug("%s(st = 0x%p, len = %d)\n", __func__, st, len);
>>> +
>>> +	ret = spi_read(st->spi, st->buffer, len);
>>> +	if (ret<  0)
>>> +		pr_err("can't read value\n");
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int max1027_read_single_value(struct iio_dev *indio_dev,
>>> +				     struct iio_chan_spec const *chan,
>>> +				     int *val, int *val2, long mask)
>> val2 and mask are not used.
> I'll remove it in v3.
>
>>> +{
>>> +	int ret;
>>> +	unsigned char reg;
>>> +	struct max1027_state *st = iio_priv(indio_dev);
>>> +
>>> +	if (iio_buffer_enabled(indio_dev)) {
>>> +		dev_warn(&indio_dev->dev, "trigger mode already enabled");
>>> +		return -EIO;
>>> +	}
>>> +
>>> +	/* Start acquisition on conversion register write */
>>> +	reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2 | MAX1027_CKS_MODE2;
>>> +	ret = max1027_write_register(st, reg);
>>> +	if (ret<  0) {
>>> +		dev_err(&indio_dev->dev,
>>> +			"Failed to configure setup register\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	/* Configure conversion register with the requested chan */
>>> +	reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel)
>>> +		| MAX1027_NOSCAN | !!(chan->type == IIO_TEMP);
>>> +	ret = max1027_write_register(st, reg);
>>> +	if (ret<  0) {
>>> +		dev_err(&indio_dev->dev,
>>> +			"Failed to configure conversion register\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	/*
>>> +	 * For an unknown reason, when we use the mode "10" (write
>>> +	 * conversion register), the it doesn't occur every time.
>> I still don't understand this comment.
> For an unknown reason, the max1027 on my armadeus apf27 don't raise
> an it when I use the mode "10" (acquisition started on convertion write).
> In fact, it's weird, there is an IT when I read temperature, but not
> when I read a voltage.
So what is "IT"? "Internally timed" or some abbreviation for interrupt?
>
> # grep max /proc/interrupts
> 223:     110213  gpio-mxc  15  max1027
> 272:     110200  max1027-trigger
>
>
> # cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw
> 2589
> # grep max /proc/interrupts
> 223:     110213  gpio-mxc  15  max1027
> 272:     110200  max1027-trigger
>
> # cat /sys/bus/iio/devices/iio\:device0/in_temp_raw
> 214
> # grep max /proc/interrupts
> 223:     110214  gpio-mxc  15  max1027
> 272:     110200  max1027-trigger
>
> So with mode "10", I use a delay of 1 ms.
>
>
>
>>> +	 * So we just wait 1 ms.
>>> +	 */
>>> +	mdelay(1);
>>> +
>>> +	/* Read result */
>>> +	ret = max1027_read_value(st, (chan->type == IIO_TEMP) ? 4 : 2);
>> I guess I didn't have a look into the datasheet before, when reviewing this part, but could you point me to where it is stated, that temperature measurements take 4 bytes?
> When the temperature is read, the voltage is also read. So 4 bytes need to be read in the FIFO,
> 2 for the temperature, 2 for the voltage.
>
> This is described in the "Internal FIFO" paragraph.
I read there: "The first 2 bytes of data read out after a temperature measurement always contain the temperature result preceded by four leading zeros, MSB first.". So my interpretation would be, that you could just read those 2 bytes as the temperature and ignore any further data. But that datasheet is not one of the best I've ever read. Any other opinions?
>
>>> +	if (ret<  0)
>>> +		return ret;
>>> +
>>> +	*val = be16_to_cpu(st->buffer[0]);
>>> +
>>> +	return IIO_VAL_INT;
>>> +}
>>> +
>>> +static int max1027_read_raw(struct iio_dev *indio_dev,
>>> +			    struct iio_chan_spec const *chan,
>>> +			    int *val, int *val2, long mask)
>>> +{
>>> +	int ret = 0;
>>> +
>>> +	switch (mask) {
>>> +	case IIO_CHAN_INFO_RAW:
>>> +		ret = max1027_read_single_value(indio_dev, chan,
>>> +						val, val2, mask);
>>> +		break;
>>> +	case IIO_CHAN_INFO_SCALE:
>>> +		switch (chan->type) {
>>> +		case IIO_TEMP:
>>> +			*val = 1;
>>> +			*val2 = 8;
>>> +			ret = IIO_VAL_FRACTIONAL;
>>> +			break;
>>> +		case IIO_VOLTAGE:
>>> +			*val = 2500;
>>> +			*val2 = 10;
>>> +			ret = IIO_VAL_FRACTIONAL_LOG2;
>>> +			break;
>>> +		default:
>>> +			ret = -EINVAL;
>>> +			break;
>>> +		};
>>> +		break;
>>> +	default:
>>> +		ret = -EINVAL;
>>> +		break;
>>> +	};
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int max1027_update_scan_mode(struct iio_dev *indio_dev,
>>> +				    const unsigned long *scan_mask)
>>> +{
>>> +	pr_debug("%s(indio_dev=0x%p, scan_mask=0x%p)\n",
>>> +		__func__, indio_dev, scan_mask);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
>>> +				  unsigned reg, unsigned writeval,
>>> +				  unsigned *readval)
>>> +{
>>> +	struct max1027_state *st = iio_priv(indio_dev);
>>> +
>>> +	if (readval != NULL)
>>> +		return -EINVAL;
>>> +
>>> +	return max1027_write_register(st, writeval);
>>> +}
>>> +
>>> +static int max1027_set_trigger_state(struct iio_trigger *trig, bool state)
>>> +{
>>> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>>> +	struct max1027_state *st = iio_priv(indio_dev);
>>> +	unsigned char reg;
>>> +	int ret;
>>> +
>>> +	if (state) {
>>> +		/* Start acquisition on cnvst */
>>> +		reg = MAX1027_SETUP_REG | MAX1027_CKS_MODE0 | MAX1027_REF_MODE2;
>>> +		ret = max1027_write_register(st, reg);
>>> +		if (ret<  0)
>>> +			return ret;
>>> +
>>> +		/* Scan from 0 to max */
>>> +		reg = MAX1027_CONV_REG | MAX1027_CHAN(0)
>>> +			| MAX1027_SCAN_N_M | MAX1027_TEMP;
>>> +		ret = max1027_write_register(st, reg);
>>> +		if (ret<  0)
>>> +			return ret;
>>> +	} else {
>>> +		/* Start acquisition on conversion register write */
>>> +		reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2 | MAX1027_CKS_MODE2;
>> Just for improved readability, keep the same order as above (MSB to LSB in your case).
> You're right, it's better, I'll fix it in v3.
>
>>> +		ret = max1027_write_register(st, reg);
>>> +		if (ret<  0)
>>> +			return ret;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static irqreturn_t max1027_interrupt_handler(int irq, void *private)
>>> +{
>>> +	struct iio_dev *indio_dev = (struct iio_dev *)private;
>>> +
>>> +	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
>>> +
>>> +	if (iio_buffer_enabled(indio_dev))
>>> +		iio_trigger_poll(indio_dev->trig, iio_get_time_ns());
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +static irqreturn_t max1027_trigger_handler(int irq, void *private)
>>> +{
>>> +	struct iio_poll_func *pf = (struct iio_poll_func *)private;
>>> +	struct iio_dev *indio_dev = pf->indio_dev;
>>> +	struct max1027_state *st = iio_priv(indio_dev);
>>> +
>>> +	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
>>> +
>>> +	/* fill buffer with all channel */
>>> +	max1027_read_value(st, indio_dev->masklength * 2);
>>> +
>>> +	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,
>>> +					   iio_get_time_ns());
>>> +
>>> +	iio_trigger_notify_done(indio_dev->trig);
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +static const struct iio_trigger_ops max1027_trigger_ops = {
>>> +	.owner = THIS_MODULE,
>>> +	.set_trigger_state =&max1027_set_trigger_state,
>>> +};
>>> +
>>> +static const struct iio_info max1027_info = {
>>> +	.driver_module = THIS_MODULE,
>>> +	.read_raw =&max1027_read_raw,
>>> +	.update_scan_mode =&max1027_update_scan_mode,
>>> +	.debugfs_reg_access =&max1027_debugfs_reg_access,
>>> +};
>>> +
>>> +static int max1027_probe(struct spi_device *spi)
>>> +{
>>> +	int err;
>>> +	struct iio_dev *indio_dev;
>>> +	struct max1027_state *st;
>>> +
>>> +	pr_debug("%s: probe(spi = 0x%p)\n", __func__, spi);
>>> +
>>> +	/* allocate iio device */
>>> +	indio_dev = devm_iio_device_alloc(&spi->dev,
>>> +					  sizeof(struct max1027_state));
>>> +	if (!indio_dev) {
>>> +		pr_err("can't allocate iio device\n");
>>> +		return -ENOMEM;
>>> +	}
>>> +
>>> +	spi_set_drvdata(spi, indio_dev);
>>> +
>>> +	st = iio_priv(indio_dev);
>>> +	st->spi = spi;
>>> +	st->buffer = NULL;
>>> +	st->info = (struct max1027_chip_info *)
>>> +		&max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];
>>> +
>>> +	/* request irq */
>>> +	err = devm_request_threaded_irq(&spi->dev, spi->irq,
>>> +					max1027_interrupt_handler,
>>> +					NULL,
>>> +					IRQF_TRIGGER_FALLING,
>>> +					spi->dev.driver->name, indio_dev);
>>> +	if (err) {
>>> +		dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
>>> +		return err;
>>> +	}
>>> +
>>> +	indio_dev->name = spi_get_device_id(spi)->name;
>>> +	indio_dev->dev.parent =&spi->dev;
>>> +	indio_dev->info =&max1027_info;
>>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>>> +	indio_dev->channels = st->info->channels;
>>> +	indio_dev->num_channels = st->info->num_channels;
>>> +	indio_dev->available_scan_masks = st->info->available_scan_masks;
>>> +
>>> +	/* Allocate buffer (data) */
>>> +	st->buffer = devm_kmalloc(&indio_dev->dev,
>>> +				  indio_dev->num_channels * 2,
>>> +				  GFP_KERNEL);
>>> +	if (st->buffer == NULL) {
>> As picky as I am, I could ask why you check for successful allocation in a different way than above for indio_dev ;-)
> I don't really know, but I'll update it to always use the same way for the "post allocation check".
> I'll update it in v3.
>
>>> +		dev_err(&indio_dev->dev, "Can't allocate bufffer\n");
>>> +		return -ENOMEM;
>>> +	}
>>> +
>>> +	/* Allocate buffer */
>>> +	err = iio_triggered_buffer_setup(indio_dev,&iio_pollfunc_store_time,
>>> +					&max1027_trigger_handler, NULL);
>>> +	if (err<  0) {
>>> +		dev_err(&indio_dev->dev, "Failed to setup buffer\n");
>>> +		return err;
>>> +	}
>>> +
>>> +	/* Allocate trigger */
>>> +	st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
>>> +							indio_dev->name);
>>> +	if (st->trig == NULL) {
>>> +		err = -ENOMEM;
>>> +		dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n");
>>> +		goto fail_trigger_alloc;
>>> +	}
>>> +
>>> +	/* configure and register trigger */
>>> +	st->trig->ops =&max1027_trigger_ops;
>>> +	st->trig->dev.parent =&spi->dev;
>>> +	iio_trigger_set_drvdata(st->trig, indio_dev);
>>> +	iio_trigger_register(st->trig);
>>> +
>>> +	/* Disable averaging */
>>> +	err = max1027_write_register(st, MAX1027_AVG_REG);
>>> +	if (err<  0) {
>>> +		dev_err(&indio_dev->dev, "Failed to configure averaging register\n");
>>> +		goto fail_dev_register;
>>> +	}
>>> +
>>> +	/* Register the device */
>>> +	err = iio_device_register(indio_dev);
>>> +	if (err<  0) {
>>> +		dev_err(&indio_dev->dev, "Failed to register iio device\n");
>>> +		goto fail_dev_register;
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +fail_dev_register:
>>> +fail_trigger_alloc:
>>> +	iio_triggered_buffer_cleanup(indio_dev);
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +static int max1027_remove(struct spi_device *spi)
>>> +{
>>> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
>>> +
>>> +	pr_debug("%s: remove(spi = 0x%p)\n", __func__, spi);
>>> +
>>> +	iio_device_unregister(indio_dev);
>>> +	iio_triggered_buffer_cleanup(indio_dev);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static struct spi_driver max1027_driver = {
>>> +	.driver = {
>>> +		.name	= "max1027",
>>> +		.owner	= THIS_MODULE,
>>> +	},
>>> +	.probe		= max1027_probe,
>>> +	.remove		= max1027_remove,
>>> +	.id_table	= max1027_id,
>>> +};
>>> +module_spi_driver(max1027_driver);
>>> +
>>> +MODULE_AUTHOR("Philippe Reynes<tremyfr@...oo.fr>");
>>> +MODULE_DESCRIPTION("MAX1027/MAX1029/MAX1031 ADC");
>>> +MODULE_LICENSE("GPL v2");
>>
> Best regards,
> Philippe
> --
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