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References: <20210616181545.496149-1-kernel@esmil.dk> <20210616181545.496149-3-kernel@esmil.dk>
 <20210617150740.GA2676642@roeck-us.net>
In-Reply-To: <20210617150740.GA2676642@roeck-us.net>
From:   Emil Renner Berthing <kernel@esmil.dk>
Date:   Thu, 17 Jun 2021 17:36:12 +0200
Message-ID: <CANBLGczCSosEP-aRCs_arfS_DRx15XRZsCZp0+TxXQNX33svvg@mail.gmail.com>
Subject: Re: [PATCH v1 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>,
        Samin Guo <samin.guo@starfivetech.com>,
        linux-hwmon@vger.kernel.org, devicetree@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Thu, 17 Jun 2021 at 17:07, Guenter Roeck <linux@roeck-us.net> wrote:
> On Wed, Jun 16, 2021 at 08:15:45PM +0200, Emil Renner Berthing wrote:
> > Register definitions based on sfctemp driver in the StarFive
> > 5.10 kernel by Samin Guo <samin.guo@starfivetech.com>.
> >
> > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > ---
> >
> > @Samin: Only the register definitions and conversion constants are left
> > from your driver, but still it would be really nice if you could reply
> > to this mail with your Signed-off-by. Thanks!
> >
> >
> >  drivers/hwmon/Kconfig   |   9 ++
> >  drivers/hwmon/Makefile  |   1 +
> >  drivers/hwmon/sfctemp.c | 309 ++++++++++++++++++++++++++++++++++++++++
>
> Documentation/hwmon/sfctemp is missing.
>
> >  3 files changed, 319 insertions(+)
> >  create mode 100644 drivers/hwmon/sfctemp.c
> >
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index 87624902ea80..fa7562920dfa 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -1751,6 +1751,15 @@ 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"
> > +     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..62a838063e4e
> > --- /dev/null
> > +++ b/drivers/hwmon/sfctemp.c
> > @@ -0,0 +1,309 @@
> > +// 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/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
>
> This may work on some systems, but on others it will result in:
>
> drivers/hwmon/sfctemp.c: In function ‘sfctemp_power_up’:
> drivers/hwmon/sfctemp.c:76:2: error: implicit declaration of function ‘writel’
>
> drivers/hwmon/sfctemp.c: In function ‘sfctemp_convert’:
> drivers/hwmon/sfctemp.c:144:17: error: implicit declaration of function ‘readl’
>
> It is necessary to include <linux/io.h>.
>
> > +
> > +/* TempSensor reset. The RSTN can be de-asserted once the analog core has
> > + * powered up. Trst(min 100ns)
> > + * 0:reset  1:de-assert */
>
> /*
>  * Please use standard multi-line comments.
>  * checkpatch would tell you, plus it has other complaints.
>  * Please run checkpatch --strict and fix what it reports.
>  */
> > +#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 calibration mode enable.
> > + * 0:disable  1:enable */
> > +#define SFCTEMP_CAL      BIT(4)
> > +
> > +/* TempSensor signature enable. Generate a toggle value outputting on DOUT for
> > + * test purpose.
> > + * 0:disable  1:enable */
> > +#define SFCTEMP_SGN      BIT(5)
> > +
> > +/* TempSensor test access control.
> > + * 0000:normal 0001:Test1  0010:Test2  0011:Test3
> > + * 0100:Test4  1000:Test8  1001:Test9 */
> > +#define SFCTEMP_TM_Pos   12
> > +#define SFCTEMP_TM_Msk   GENMASK(15, 12)
>
> Defines should upper case. Besides, the above defines are not
> used. Please remove unused defines, and please rename the others
> to be upper case only.
>
> > +
> > +/* TempSensor conversion value output.
> > + * Temp(c)=DOUT*Y/4094 - K */
> > +#define SFCTEMP_DOUT_Pos 16
> > +#define SFCTEMP_DOUT_Msk GENMASK(27, 16)
> > +
> > +/* TempSensor digital test output. */
> > +#define SFCTEMP_DIGO     BIT(31)
> > +
> > +/* DOUT to Celcius conversion constants */
> > +#define SFCTEMP_Y1000 237500L
> > +#define SFCTEMP_Z       4094L
>
> Please use
>
> #define<space><definition><tab><value>, eg
>
> #define SFCTEMP_Y1000   237500L
> #define SFCTEMP_Z       4094L
>
> for all defines.
>
> > +#define SFCTEMP_K1000  81100L
> > +
> > +struct sfctemp {
> > +     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 int sfctemp_convert(struct sfctemp *sfctemp, long *val)
> > +{
> > +     long ret;
>
> Why long ? Sure, wait_for_completion_interruptible_timeout()
> returns a long, but it will never return a value large enough to warrant
> a long here.
>
> > +
> > +     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;
> > +
> > +     /* calculate temperature in milli Celcius */
> > +     *val = (long)((readl(sfctemp->regs) & SFCTEMP_DOUT_Msk) >> SFCTEMP_DOUT_Pos)
> > +             * SFCTEMP_Y1000 / SFCTEMP_Z - SFCTEMP_K1000;
> > +
> > +     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;
> > +     long val;
> > +     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 = sfctemp_enable(sfctemp);
> > +     if (ret)
> > +             return ret;
>
> Please consider adding devm_add_action_or_reset() to disable the sensor.
> Then you can use devm_hwmon_device_register_with_info(), and there is
> no need for a remove function.
> > +
> > +     hwmon_dev = hwmon_device_register_with_info(dev, pdev->name, sfctemp,
> > +                                                 &sfctemp_chip_info, NULL);
> > +     if (IS_ERR(hwmon_dev))
> > +             return PTR_ERR(hwmon_dev);
> > +
> > +     /* do a conversion to check everything works */
> > +     ret = sfctemp_convert(sfctemp, &val);
>
> Please drop this check; it will result in substantial boot delays.
> The assumption is the the hardware works; the system should not be
> optimized (slowed down) to handle a potential and hopefully rare
> failure case.
>
> > +     if (ret) {
> > +             hwmon_device_unregister(hwmon_dev);
> > +             return ret;
> > +     }
> > +
> > +     dev_info(dev, "%ld.%03ld C\n", val / 1000, val % 1000);
>
> Please drop this message. Anyone interested in boot-time temperature
> readings can add a script and get it from sysfs attributes as needed.
>
> > +     return 0;
> > +}
> > +
> > +static int sfctemp_remove(struct platform_device *pdev)
> > +{
> > +     struct device *dev = &pdev->dev;
> > +     struct sfctemp *sfctemp = dev_get_drvdata(dev);
> > +
> > +     hwmon_device_unregister(dev);
> > +     return sfctemp_disable(sfctemp);
> > +}
> > +
> > +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,
> > +     .remove = sfctemp_remove,
> > +};
> > +module_platform_driver(sfctemp_driver);
> > +
> > +MODULE_AUTHOR("Emil Renner Berthing");
> > +MODULE_DESCRIPTION("StarFive JH7100 temperature sensor driver");
> > +MODULE_LICENSE("GPL");

Hi Guenter,

Thanks for the review. It all sounds reasonable. I'll address it all in v2.

/Emil