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 <20210628150803.GA441036@roeck-us.net>
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From:   Esmil <esmil@mailme.dk>
Date:   Mon, 28 Jun 2021 17:13:29 +0200
Message-ID: <CANBLGcyP8cZEEQqJEw_u0F=AW-Qw3uN9WmMb4E_60Sk7qcpYmg@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] hwmon: (sfctemp) Add StarFive JH7100 temperature sensor
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Jean Delvare <jdelvare@suse.com>, Rob Herring <robh+dt@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Samin Guo <samin.guo@starfivetech.com>,
        linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org,
        linux-doc@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Mon, 28 Jun 2021 at 17:08, Guenter Roeck <linux@roeck-us.net> wrote:
> On Thu, Jun 24, 2021 at 06:21:08PM +0200, Emil Renner Berthing wrote:
> > From: Emil Renner Berthing <kernel@esmil.dk>
> >
> > Register definitions and conversion constants based on sfctemp driver by
> > Samin in the StarFive 5.10 kernel.
> >
> > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
> > ---
> >  Documentation/hwmon/index.rst   |   1 +
> >  Documentation/hwmon/sfctemp.rst |  32 ++++
> >  MAINTAINERS                     |   8 +
> >  drivers/hwmon/Kconfig           |  10 ++
> >  drivers/hwmon/Makefile          |   1 +
> >  drivers/hwmon/sfctemp.c         | 288 ++++++++++++++++++++++++++++++++
> >  6 files changed, 340 insertions(+)
> >  create mode 100644 Documentation/hwmon/sfctemp.rst
> >  create mode 100644 drivers/hwmon/sfctemp.c
> >
> > diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> > index 9ed60fa84cbe..f23308e97d2e 100644
> > --- a/Documentation/hwmon/index.rst
> > +++ b/Documentation/hwmon/index.rst
> > @@ -161,6 +161,7 @@ Hardware Monitoring Kernel Drivers
> >     sch5627
> >     sch5636
> >     scpi-hwmon
> > +   sfctemp
> >     sht15
> >     sht21
> >     sht3x
> > diff --git a/Documentation/hwmon/sfctemp.rst b/Documentation/hwmon/sfctemp.rst
> > new file mode 100644
> > index 000000000000..465edce2fea5
> > --- /dev/null
> > +++ b/Documentation/hwmon/sfctemp.rst
> > @@ -0,0 +1,32 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +Kernel driver sfctemp
> > +=====================
> > +
> > +Supported chips:
> > + - StarFive JH7100
> > +
> > +Authors:
> > + - Emil Renner Berthing <kernel@esmil.dk>
> > +
> > +Description
> > +-----------
> > +
> > +This driver adds support for reading the built-in temperature sensor on the
> > +JH7100 RISC-V SoC by StarFive Technology Co. Ltd.
> > +
> > +``sysfs`` interface
> > +-------------------
> > +
> > +The temperature sensor can be enabled, disabled and queried via the standard
> > +hwmon interface in sysfs under ``/sys/class/hwmon/hwmonX`` for some value of
> > +``X``:
> > +
> > +================ ==== =============================================
> > +Name             Perm Description
> > +================ ==== =============================================
> > +temp1_enable     RW   Enable or disable temperature sensor.
> > +                      Automatically enabled by the driver,
> > +                      but may be disabled to save power.
> > +temp1_input      RO   Temperature reading in milli-degrees Celsius.
> > +================ ==== =============================================
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 8c5ee008301a..a7d25a672270 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -16535,6 +16535,14 @@ L:   netdev@vger.kernel.org
> >  S:   Supported
> >  F:   drivers/net/ethernet/sfc/
> >
> > +SFCTEMP HWMON DRIVER
> > +M:   Emil Renner Berthing <kernel@esmil.dk>
> > +L:   linux-hwmon@vger.kernel.org
> > +S:   Maintained
> > +F:   Documentation/devicetree/bindings/hwmon/starfive,jh7100-temp.yaml
> > +F:   Documentation/hwmon/sfctemp.rst
> > +F:   drivers/hwmon/sfctemp.c
> > +
> >  SFF/SFP/SFP+ MODULE SUPPORT
> >  M:   Russell King <linux@armlinux.org.uk>
> >  L:   netdev@vger.kernel.org
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index 87624902ea80..7da8fd8beb06 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -1751,6 +1751,16 @@ config SENSORS_STTS751
> >         This driver can also be built as a module. If so, the module
> >         will be called stts751.
> >
> > +config SENSORS_SFCTEMP
> > +     tristate "Starfive JH7100 temperature sensor"
> > +     depends on OF && (RISCV || COMPILE_TEST)
> > +     help
> > +       If you say yes here you get support for temperature sensor
> > +       on the Starfive JH7100 SoC.
> > +
> > +       This driver can also be built as a module.  If so, the module
> > +       will be called sfctemp.
> > +
> >  config SENSORS_SMM665
> >       tristate "Summit Microelectronics SMM665"
> >       depends on I2C
> > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> > index 59e78bc212cf..3723eb580bf3 100644
> > --- a/drivers/hwmon/Makefile
> > +++ b/drivers/hwmon/Makefile
> > @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_SBTSI)       += sbtsi_temp.o
> >  obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
> >  obj-$(CONFIG_SENSORS_SCH5627)        += sch5627.o
> >  obj-$(CONFIG_SENSORS_SCH5636)        += sch5636.o
> > +obj-$(CONFIG_SENSORS_SFCTEMP)        += sfctemp.o
> >  obj-$(CONFIG_SENSORS_SL28CPLD)       += sl28cpld-hwmon.o
> >  obj-$(CONFIG_SENSORS_SHT15)  += sht15.o
> >  obj-$(CONFIG_SENSORS_SHT21)  += sht21.o
> > diff --git a/drivers/hwmon/sfctemp.c b/drivers/hwmon/sfctemp.c
> > new file mode 100644
> > index 000000000000..4328aacf9272
> > --- /dev/null
> > +++ b/drivers/hwmon/sfctemp.c
> > @@ -0,0 +1,288 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk>
> > + * Copyright (C) 2021 Samin Guo <samin.guo@starfivetech.com>
> > + */
> > +#include <linux/completion.h>
> > +#include <linux/delay.h>
> > +#include <linux/hwmon.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +
> > +/*
> > + * TempSensor reset. The RSTN can be de-asserted once the analog core has
> > + * powered up. Trst(min 100ns)
> > + * 0:reset  1:de-assert
> > + */
> > +#define SFCTEMP_RSTN BIT(0)
> > +
> > +/*
> > + * TempSensor analog core power down. The analog core will be powered up
> > + * Tpu(min 50us) after PD is de-asserted. RSTN should be held low until the
> > + * analog core is powered up.
> > + * 0:power up  1:power down
> > + */
> > +#define SFCTEMP_PD   BIT(1)
> > +
> > +/*
> > + * TempSensor start conversion enable.
> > + * 0:disable  1:enable
> > + */
> > +#define SFCTEMP_RUN  BIT(2)
> > +
> > +/*
> > + * TempSensor conversion value output.
> > + * Temp(C)=DOUT*Y/4094 - K
> > + */
> > +#define SFCTEMP_DOUT_POS     16
> > +#define SFCTEMP_DOUT_MSK     GENMASK(27, 16)
> > +
> > +/* DOUT to Celcius conversion constants */
> > +#define SFCTEMP_Y1000        237500L
> > +#define SFCTEMP_Z    4094L
> > +#define SFCTEMP_K1000        81100L
> > +
> > +struct sfctemp {
> > +     /* serialize access to hardware register and enabled below */
> > +     struct mutex lock;
> > +     struct completion conversion_done;
> > +     void __iomem *regs;
> > +     bool enabled;
> > +};
> > +
> > +static irqreturn_t sfctemp_isr(int irq, void *data)
> > +{
> > +     struct sfctemp *sfctemp = data;
> > +
> > +     complete(&sfctemp->conversion_done);
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +static void sfctemp_power_up(struct sfctemp *sfctemp)
> > +{
> > +     /* make sure we're powered down first */
> > +     writel(SFCTEMP_PD, sfctemp->regs);
> > +     udelay(1);
> > +
> > +     writel(0, sfctemp->regs);
> > +     /* wait t_pu(50us) + t_rst(100ns) */
> > +     usleep_range(60, 200);
> > +
> > +     /* de-assert reset */
> > +     writel(SFCTEMP_RSTN, sfctemp->regs);
> > +     udelay(1); /* wait t_su(500ps) */
> > +}
> > +
> > +static void sfctemp_power_down(struct sfctemp *sfctemp)
> > +{
> > +     writel(SFCTEMP_PD, sfctemp->regs);
> > +}
> > +
> > +static void sfctemp_run_single(struct sfctemp *sfctemp)
> > +{
> > +     writel(SFCTEMP_RSTN | SFCTEMP_RUN, sfctemp->regs);
> > +     udelay(1);
> > +     writel(SFCTEMP_RSTN, sfctemp->regs);
> > +}
> > +
> > +static int sfctemp_enable(struct sfctemp *sfctemp)
> > +{
> > +     mutex_lock(&sfctemp->lock);
> > +     if (sfctemp->enabled)
> > +             goto done;
> > +
> > +     sfctemp_power_up(sfctemp);
> > +     sfctemp->enabled = true;
> > +done:
> > +     mutex_unlock(&sfctemp->lock);
> > +     return 0;
> > +}
> > +
> > +static int sfctemp_disable(struct sfctemp *sfctemp)
> > +{
> > +     mutex_lock(&sfctemp->lock);
> > +     if (!sfctemp->enabled)
> > +             goto done;
> > +
> > +     sfctemp_power_down(sfctemp);
> > +     sfctemp->enabled = false;
> > +done:
> > +     mutex_unlock(&sfctemp->lock);
> > +     return 0;
> > +}
> > +
> > +static void sfctemp_disable_action(void *data)
> > +{
> > +     sfctemp_disable(data);
> > +}
> > +
> > +static int sfctemp_convert(struct sfctemp *sfctemp, long *val)
> > +{
> > +     int ret;
> > +
> > +     mutex_lock(&sfctemp->lock);
> > +     if (!sfctemp->enabled) {
> > +             ret = -ENODATA;
> > +             goto out;
> > +     }
> > +
> > +     sfctemp_run_single(sfctemp);
> > +
> > +     ret = wait_for_completion_interruptible_timeout(&sfctemp->conversion_done,
> > +                                                     msecs_to_jiffies(10));
> > +     if (ret < 0)
> > +             goto out;
>
> Does this need to handle timeouts ?
>
>         if (ret == 0)
>                 return -ETIMEDOUT;

Oh yes. Good catch. I thought it would automatically return -ETIMEDOUT
on timeout. I'll add that to the next version.

> > +     ret = 0;
> > +out:
> > +     mutex_unlock(&sfctemp->lock);
> > +     return ret;
> > +}
> > +
> > +static umode_t sfctemp_is_visible(const void *data, enum hwmon_sensor_types type,
> > +                               u32 attr, int channel)
> > +{
> > +     switch (type) {
> > +     case hwmon_temp:
> > +             switch (attr) {
> > +             case hwmon_temp_enable:
> > +                     return 0644;
> > +             case hwmon_temp_input:
> > +                     return 0444;
> > +             }
> > +             return 0;
> > +     default:
> > +             return 0;
> > +     }
> > +}
> > +
> > +static int sfctemp_read(struct device *dev, enum hwmon_sensor_types type,
> > +                     u32 attr, int channel, long *val)
> > +{
> > +     struct sfctemp *sfctemp = dev_get_drvdata(dev);
> > +
> > +     switch (type) {
> > +     case hwmon_temp:
> > +             switch (attr) {
> > +             case hwmon_temp_enable:
> > +                     *val = sfctemp->enabled;
> > +                     return 0;
> > +             case hwmon_temp_input:
> > +                     return sfctemp_convert(sfctemp, val);
> > +             }
> > +             return -EINVAL;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static int sfctemp_write(struct device *dev, enum hwmon_sensor_types type,
> > +                      u32 attr, int channel, long val)
> > +{
> > +     struct sfctemp *sfctemp = dev_get_drvdata(dev);
> > +
> > +     switch (type) {
> > +     case hwmon_temp:
> > +             switch (attr) {
> > +             case hwmon_temp_enable:
> > +                     if (val == 0)
> > +                             return sfctemp_disable(sfctemp);
> > +                     if (val == 1)
> > +                             return sfctemp_enable(sfctemp);
> > +                     break;
> > +             }
> > +             return -EINVAL;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +
> > +static const struct hwmon_channel_info *sfctemp_info[] = {
> > +     HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
> > +     HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT),
> > +     NULL
> > +};
> > +
> > +static const struct hwmon_ops sfctemp_hwmon_ops = {
> > +     .is_visible = sfctemp_is_visible,
> > +     .read = sfctemp_read,
> > +     .write = sfctemp_write,
> > +};
> > +
> > +static const struct hwmon_chip_info sfctemp_chip_info = {
> > +     .ops = &sfctemp_hwmon_ops,
> > +     .info = sfctemp_info,
> > +};
> > +
> > +static int sfctemp_probe(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     struct device *hwmon_dev;
> > +     struct resource *mem;
> > +     struct sfctemp *sfctemp;
> > +     int ret;
> > +
> > +     sfctemp = devm_kzalloc(dev, sizeof(*sfctemp), GFP_KERNEL);
> > +     if (!sfctemp)
> > +             return -ENOMEM;
> > +
> > +     dev_set_drvdata(dev, sfctemp);
> > +     mutex_init(&sfctemp->lock);
> > +     init_completion(&sfctemp->conversion_done);
> > +
> > +     mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +     sfctemp->regs = devm_ioremap_resource(dev, mem);
> > +     if (IS_ERR(sfctemp->regs))
> > +             return PTR_ERR(sfctemp->regs);
> > +
> > +     ret = platform_get_irq(pdev, 0);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ret = devm_request_irq(dev, ret, sfctemp_isr,
> > +                            IRQF_SHARED, pdev->name, sfctemp);
> > +     if (ret) {
> > +             dev_err(dev, "request irq failed: %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = devm_add_action(dev, sfctemp_disable_action, sfctemp);
> > +     if (ret)
> > +             return ret;
> > +
> > +     ret = sfctemp_enable(sfctemp);
> > +     if (ret)
> > +             return ret;
> > +
> > +     hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev->name, sfctemp,
> > +                                                      &sfctemp_chip_info, NULL);
> > +     return PTR_ERR_OR_ZERO(hwmon_dev);
> > +}
> > +
> > +static const struct of_device_id sfctemp_of_match[] = {
> > +     { .compatible = "starfive,jh7100-temp" },
> > +     { /* sentinel */ }
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, sfctemp_of_match);
> > +
> > +static struct platform_driver sfctemp_driver = {
> > +     .driver = {
> > +             .name = "sfctemp",
> > +             .of_match_table = of_match_ptr(sfctemp_of_match),
> > +     },
> > +     .probe  = sfctemp_probe,
> > +};
> > +module_platform_driver(sfctemp_driver);
> > +
> > +MODULE_AUTHOR("Emil Renner Berthing");
> > +MODULE_DESCRIPTION("StarFive JH7100 temperature sensor driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.32.0
> >