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

From: Jonathan Cameron <[email-masked]>
Date: Tue, 9 Jun 2020 09:38:08 +0100

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.

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.

> +
> +#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.

> +	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. 

> +
> +	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
> 
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