Subject: Re: [PATCH v2 3/3] hwmon: sparx5: Add Sparx5 SoC temperature driver

From: Jonathan Cameron <[email-masked]>
Date: Tue, 9 Jun 2020 14:03:13 +0100

On Tue, 9 Jun 2020 14:20:37 +0200
Lars Povlsen <[email-masked]> wrote:

> Jonathan Cameron writes:
> 
> > On Tue, 9 Jun 2020 09:49:40 +0200
> > Lars Povlsen <[email-masked]> wrote:
> >  
> >> This patch adds a temperature sensor driver to the Sparx5 SoC.
> >>
> >> Reviewed-by: Alexandre Belloni <[email-masked]>
> >> Signed-off-by: Lars Povlsen <[email-masked]>  
> >
> > Hi.  Quick drive by review whilst waiting for coffee time...
> >
> > A few minor suggestions inline.
> >  
> 
> Much appreciated!
> 
> > Thanks,
> >
> > Jonathan
> >  
> >> ---
> >>  drivers/hwmon/Kconfig       |  10 +++
> >>  drivers/hwmon/Makefile      |   2 +-
> >>  drivers/hwmon/sparx5-temp.c | 152
> >> ++++++++++++++++++++++++++++++++++++ 3 files changed, 163
> >> insertions(+), 1 deletion(-) create mode 100644
> >> drivers/hwmon/sparx5-temp.c
> >>
> >> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> >> index 288ae9f63588c..ec6bb8b8b12df 100644
> >> --- a/drivers/hwmon/Kconfig
> >> +++ b/drivers/hwmon/Kconfig
> >> @@ -515,6 +515,16 @@ config SENSORS_I5K_AMB
> >>         This driver can also be built as a module. If so, the
> >> module will be called i5k_amb.
> >>
> >> +config SENSORS_SPARX5
> >> +     tristate "Sparx5 SoC temperature sensor"
> >> +     depends on ARCH_SPARX5  
> > Anything stop this building with COMPILE_TEST?
> >
> > That will great increase automated build coverage.
> >  
> >> +     help
> >> +       If you say yes here you get support for temperature
> >> monitoring
> >> +       with the Microchip Sparx5 SoC.
> >> +
> >> +       This driver can also be built as a module. If so, the
> >> module
> >> +       will be called sparx5-temp.
> >> +
> >>  config SENSORS_F71805F
> >>       tristate "Fintek F71805F/FG, F71806F/FG and F71872F/FG"
> >>       depends on !PPC
> >> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> >> index 3e32c21f5efe3..144f09993a3f4 100644
> >> --- a/drivers/hwmon/Makefile
> >> +++ b/drivers/hwmon/Makefile
> >> @@ -66,6 +66,7 @@ obj-$(CONFIG_SENSORS_DS1621)        += ds1621.o
> >>  obj-$(CONFIG_SENSORS_EMC1403)        += emc1403.o
> >>  obj-$(CONFIG_SENSORS_EMC2103)        += emc2103.o
> >>  obj-$(CONFIG_SENSORS_EMC6W201)       += emc6w201.o
> >> +obj-$(CONFIG_SENSORS_SPARX5) += sparx5-temp.o
> >>  obj-$(CONFIG_SENSORS_F71805F)        += f71805f.o
> >>  obj-$(CONFIG_SENSORS_F71882FG)       += f71882fg.o
> >>  obj-$(CONFIG_SENSORS_F75375S)        += f75375s.o
> >> @@ -193,4 +194,3 @@ obj-$(CONFIG_SENSORS_OCC) += occ/
> >>  obj-$(CONFIG_PMBUS)          += pmbus/
> >>
> >>  ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG
> >> -
> >> diff --git a/drivers/hwmon/sparx5-temp.c
> >> b/drivers/hwmon/sparx5-temp.c new file mode 100644
> >> index 0000000000000..2e754462b6010
> >> --- /dev/null
> >> +++ b/drivers/hwmon/sparx5-temp.c
> >> @@ -0,0 +1,152 @@
> >> +// SPDX-License-Identifier: GPL-2.0-or-later
> >> +/* Sparx5 SoC temperature sensor driver
> >> + *
> >> + * Copyright (C) 2020 Lars Povlsen <[email-masked]>
> >> + */
> >> +
> >> +#include <linux/module.h>
> >> +#include <linux/init.h>
> >> +#include <linux/hwmon.h>
> >> +#include <linux/io.h>
> >> +#include <linux/of_device.h>  
> > I think you only have this to define the id table?
> >
> > If so, perhaps better to include mod_devicetable.h and not include
> > the of header.  
> 
> Well, I ended up needed other, so it became:
> 
> -#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/mod_devicetable.h>
> 
> Other of these drivers seem to use "linux/of_device.h" as well?

Yeah. Lots of drivers take the lazy approach of including of_device.h
but doesn't mean we can't do better.

:)

Preference is always to include a little as possible (in terms of the
tree of headers rather than include lines in a file)

J

> 
> >  
> >> +
> >> +#define TEMP_CTRL            0
> >> +#define TEMP_CFG             4
> >> +#define  TEMP_CFG_CYCLES     GENMASK(24, 15)
> >> +#define  TEMP_CFG_CYCLES_OFF 15  
> >
> > Could you used FIELD_PREP etc to avoid having to have both
> > the mask and offset defined here?
> >  
> >> +#define  TEMP_CFG_ENA                BIT(0)
> >> +#define TEMP_STAT            8
> >> +#define  TEMP_STAT_VALID     BIT(12)
> >> +#define  TEMP_STAT_TEMP              GENMASK(11, 0)
> >> +
> >> +struct s5_hwmon {
> >> +     void __iomem *base;
> >> +};
> >> +
> >> +static void s5_temp_enable(struct s5_hwmon *hwmon)
> >> +{
> >> +     u32 val = readl(hwmon->base + TEMP_CFG);
> >> +     u32 clk = 250;
> >> +
> >> +     val &= ~TEMP_CFG_CYCLES;
> >> +     val |= (clk << TEMP_CFG_CYCLES_OFF);
> >> +     val |= TEMP_CFG_ENA;
> >> +
> >> +     writel(val, hwmon->base + TEMP_CFG);
> >> +}
> >> +
> >> +static void s5_temp_disable(void *data)
> >> +{
> >> +     struct s5_hwmon *hwmon = data;
> >> +     u32 val = readl(hwmon->base + TEMP_CFG);
> >> +
> >> +     val &= ~TEMP_CFG_ENA;
> >> +
> >> +     writel(val, hwmon->base + TEMP_CFG);
> >> +}
> >> +
> >> +static int s5_read(struct device *dev, enum hwmon_sensor_types
> >> type,
> >> +                u32 attr, int channel, long *temp)
> >> +{
> >> +     struct s5_hwmon *hwmon = dev_get_drvdata(dev);
> >> +     int rc = 0, value;
> >> +     u32 stat;
> >> +
> >> +     switch (attr) {
> >> +     case hwmon_temp_input:
> >> +             stat = readl_relaxed(hwmon->base + TEMP_STAT);
> >> +             if (!(stat & TEMP_STAT_VALID))
> >> +                     return -EIO;
> >> +             value = stat & TEMP_STAT_TEMP;
> >> +             value = DIV_ROUND_CLOSEST(value * 3522, 4096) - 1094;
> >> +             value *= 100;
> >> +             *temp = value;
> >> +             break;
> >> +     default:
> >> +             rc = -EOPNOTSUPP;
> >> +             break;
> >> +     }
> >> +
> >> +     return rc;
> >> +}
> >> +
> >> +static umode_t s5_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 struct hwmon_channel_info *s5_info[] = {
> >> +     HWMON_CHANNEL_INFO(chip,
> >> +                        HWMON_C_REGISTER_TZ),
> >> +     HWMON_CHANNEL_INFO(temp,
> >> +                        HWMON_T_INPUT),  
> >
> > Excess line breaks.  The above 2 would be more readable on one line
> > each. 
> 
> Right.
> 
> >> +     NULL
> >> +};
> >> +
> >> +static const struct hwmon_ops s5_hwmon_ops = {
> >> +     .is_visible = s5_is_visible,
> >> +     .read = s5_read,
> >> +};
> >> +
> >> +static const struct hwmon_chip_info s5_chip_info = {
> >> +     .ops = &s5_hwmon_ops,
> >> +     .info = s5_info,
> >> +};
> >> +
> >> +static int s5_temp_probe(struct platform_device *pdev)
> >> +{
> >> +     struct device *hwmon_dev;
> >> +     struct s5_hwmon *hwmon;
> >> +     int err;
> >> +
> >> +     hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
> >> +     if (!hwmon)
> >> +             return -ENOMEM;
> >> +
> >> +     hwmon->base = devm_platform_ioremap_resource(pdev, 0);
> >> +     if (IS_ERR(hwmon->base))
> >> +             return PTR_ERR(hwmon->base);
> >> +
> >> +     err = devm_add_action(&pdev->dev, s5_temp_disable, hwmon);
> >> +     if (err)
> >> +             return err;  
> >
> > Probably just my linear way of thinking, but unusual to put error
> > handling / remove stuff in place _before_ the thing it's unwinding.
> >
> > We have devm_add_action_or_reset to make it safe to call this after
> > the thing it unwinds.
> >  
> 
> Seems I got this "backwardness" from ltq-cputemp.c. However, its
> totally unneeded here, so I'll just remove it.
> 
> Thanks!
> 
> ---Lars
> 
> >> +
> >> +     s5_temp_enable(hwmon);
> >> +
> >> +     hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> >> +                                                      "s5_temp",
> >> +                                                      hwmon,
> >> +
> >> &s5_chip_info,
> >> +                                                      NULL);
> >> +
> >> +     return PTR_ERR_OR_ZERO(hwmon_dev);
> >> +}
> >> +
> >> +const struct of_device_id s5_temp_match[] = {
> >> +     { .compatible = "microchip,sparx5-temp" },
> >> +     {},
> >> +};
> >> +MODULE_DEVICE_TABLE(of, s5_temp_match);
> >> +
> >> +static struct platform_driver s5_temp_driver = {
> >> +     .probe = s5_temp_probe,
> >> +     .driver = {
> >> +             .name = "sparx5-temp",
> >> +             .of_match_table = s5_temp_match,
> >> +     },
> >> +};
> >> +
> >> +module_platform_driver(s5_temp_driver);
> >> +
> >> +MODULE_AUTHOR("Lars Povlsen <[email-masked]>");
> >> +MODULE_DESCRIPTION("Sparx5 SoC temperature sensor driver");
> >> +MODULE_LICENSE("GPL");
> >> --
> >> 2.27.0
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> [email-masked]
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel  
> 

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