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Date: Tue, 27 Aug 2019 03:02:40 +0000
From: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
To: Guenter Roeck <linux@...ck-us.net>
CC: Jean Delvare <jdelvare@...e.com>, Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
"linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] hwmon: Add Synaptics AS370 PVT sensor driver
Hi Guenter,
On Mon, 26 Aug 2019 06:44:34 -0700 Guenter Roeck wrote:
>
>
> On 8/26/19 3:01 AM, Jisheng Zhang wrote:
> > Add a new driver for Synaptics AS370 PVT sensors. Currently, only
> > temperature is supported.
> >
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@...aptics.com>
> > ---
> > drivers/hwmon/Kconfig | 10 +++
> > drivers/hwmon/Makefile | 1 +
> > drivers/hwmon/as370-hwmon.c | 158 ++++++++++++++++++++++++++++++++++++
> > 3 files changed, 169 insertions(+)
> > create mode 100644 drivers/hwmon/as370-hwmon.c
> >
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index 650dd71f9724..d31610933faa 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -246,6 +246,16 @@ config SENSORS_ADT7475
> > This driver can also be built as a module. If so, the module
> > will be called adt7475.
> >
> > +config SENSORS_AS370
> > + tristate "Synaptics AS370 SoC hardware monitoring driver"
>
> I think this needs "depends on HAS_IOMEM".
HWMON depends on HAS_IOMEM, so the dependency has been required
by the common HWMON, we don't need it here.
>
> > + help
> > + If you say yes here you get support for the PVT sensors of
> > + the Synaptics AS370 SoC
> > +
> > + This driver can also be built as a module. If so, the module
> > + will be called as370-hwmon.
> > +
> > +
> > config SENSORS_ASC7621
> > tristate "Andigilog aSC7621"
> > depends on I2C
> > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> > index 8db472ea04f0..252e8a4c9781 100644
> > --- a/drivers/hwmon/Makefile
> > +++ b/drivers/hwmon/Makefile
> > @@ -48,6 +48,7 @@ obj-$(CONFIG_SENSORS_ADT7475) += adt7475.o
> > obj-$(CONFIG_SENSORS_APPLESMC) += applesmc.o
> > obj-$(CONFIG_SENSORS_ARM_SCMI) += scmi-hwmon.o
> > obj-$(CONFIG_SENSORS_ARM_SCPI) += scpi-hwmon.o
> > +obj-$(CONFIG_SENSORS_AS370) += as370-hwmon.o
> > obj-$(CONFIG_SENSORS_ASC7621) += asc7621.o
> > obj-$(CONFIG_SENSORS_ASPEED) += aspeed-pwm-tacho.o
> > obj-$(CONFIG_SENSORS_ATXP1) += atxp1.o
> > diff --git a/drivers/hwmon/as370-hwmon.c b/drivers/hwmon/as370-hwmon.c
> > new file mode 100644
> > index 000000000000..98dfba45e1b0
> > --- /dev/null
> > +++ b/drivers/hwmon/as370-hwmon.c
> > @@ -0,0 +1,158 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Synaptics AS370 SoC Hardware Monitoring Driver
> > + *
> > + * Copyright (C) 2018 Synaptics Incorporated
> > + * Author: Jisheng Zhang <jszhang@...nel.org>
> > + */
> > +
> > +#include <linux/bitops.h>
> > +#include <linux/delay.h>
>
> Unnecessary include file.
will remove it in newer version.
>
> > +#include <linux/hwmon.h>
> > +#include <linux/init.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +
> > +#define CTRL 0x0
> > +#define PD BIT(0)
> > +#define EN BIT(1)
> > +#define T_SEL BIT(2)
> > +#define V_SEL BIT(3)
> > +#define NMOS_SEL BIT(8)
> > +#define PMOS_SEL BIT(9)
> > +#define STS 0x4
> > +#define BN_MASK (0xfff << 0)
>
> How about using GENMASK() ?
Good idea.
>
> > +#define EOC BIT(12)
> > +
> > +struct as370_hwmon {
> > + void __iomem *base;
> > +};
> > +
> > +static void init_pvt(struct as370_hwmon *hwmon)
> > +{
> > + u32 val;
> > + void __iomem *addr = hwmon->base + CTRL;
> > +
> > + val = PD;
> > + writel_relaxed(val, addr);
> > + val |= T_SEL;
> > + val &= ~V_SEL;
> > + val &= ~NMOS_SEL;
> > + val &= ~PMOS_SEL;
>
> What is the point of this ? We know that val == PD here.
yes, could be removed
>
> > + writel_relaxed(val, addr);
> > + val |= EN;
> > + writel_relaxed(val, addr);
> > + val &= ~PD;
> > + writel_relaxed(val, addr);
> > +}
> > +
> > +static int read_pvt(struct as370_hwmon *hwmon)
> > +{
> > + return readl_relaxed(hwmon->base + STS) & BN_MASK;
> > +}
>
> Please fold into the calling code.
>
> > +
> > +static int as370_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> > + u32 attr, int channel, long *temp)
> > +{
> > + int val;
> > + struct as370_hwmon *hwmon = dev_get_drvdata(dev);
> > +
> > + switch (attr) {
> > + case hwmon_temp_input:
> > + val = read_pvt(hwmon);
> > + if (val < 0)
> > + return val;
>
> read_pvt() doesn't return a negative error code. This check is unnecessary.
>
> > + *temp = val * 251802 / 4096 - 85525;
>
> This results in rounding down the reported temperature. It is ok if it is
> what you want; otherwise, I would suggest to use DIV_ROUND_CLOSEST().
Good idea.
Thanks for your review,
Jisheng
>
> > + break;
> > + default:
> > + return -EOPNOTSUPP;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static umode_t
> > +as370_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
> > + u32 attr, int channel)
> > +{
> > + if (type != hwmon_temp)
> > + return 0;
> > +
> > + switch (attr) {
> > + case hwmon_temp_input:
> > + return 0444;
> > + default:
> > + return 0;
> > + }
> > +}
> > +
> > +static const u32 as370_hwmon_temp_config[] = {
> > + HWMON_T_INPUT,
> > + 0
> > +};
> > +
> > +static const struct hwmon_channel_info as370_hwmon_temp = {
> > + .type = hwmon_temp,
> > + .config = as370_hwmon_temp_config,
> > +};
> > +
> > +static const struct hwmon_channel_info *as370_hwmon_info[] = {
> > + &as370_hwmon_temp,
> > + NULL
> > +};
> > +
> > +static const struct hwmon_ops as370_hwmon_ops = {
> > + .is_visible = as370_hwmon_is_visible,
> > + .read = as370_hwmon_read,
> > +};
> > +
> > +static const struct hwmon_chip_info as370_chip_info = {
> > + .ops = &as370_hwmon_ops,
> > + .info = as370_hwmon_info,
> > +};
> > +
> > +static int as370_hwmon_probe(struct platform_device *pdev)
> > +{
> > + struct resource *res;
> > + struct device *hwmon_dev;
> > + struct as370_hwmon *hwmon;
> > + struct device *dev = &pdev->dev;
> > +
> > + hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
> > + if (!hwmon)
> > + return -ENOMEM;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + hwmon->base = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(hwmon->base))
> > + return PTR_ERR(hwmon->base);
> > +
> > + init_pvt(hwmon);
> > +
> > + hwmon_dev = devm_hwmon_device_register_with_info(dev,
> > + "as370_hwmon",
>
> The "_hwmon" seems unnecessary. It will show up in "sensors" as part
> of the sensor name. Is this really what you want ?
>
> > + hwmon,
> > + &as370_chip_info,
> > + NULL);
> > + return PTR_ERR_OR_ZERO(hwmon_dev);
> > +}
> > +
> > +static const struct of_device_id as370_hwmon_match[] = {
> > + { .compatible = "syna,as370-hwmon" },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, as370_hwmon_match);
> > +
> > +static struct platform_driver as370_hwmon_driver = {
> > + .probe = as370_hwmon_probe,
> > + .driver = {
> > + .name = "as370-hwmon",
> > + .of_match_table = as370_hwmon_match,
> > + },
> > +};
> > +module_platform_driver(as370_hwmon_driver);
> > +
> > +MODULE_AUTHOR("Jisheng Zhang<jszhang@...nel.org>");
> > +MODULE_DESCRIPTION("Synaptics AS370 SoC hardware monitor");
> > +MODULE_LICENSE("GPL v2");
> >
>
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