linux-kernel - Re: [PATCH v3 9/9] rtc: isl12022: add support for temperature sensor

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Date:   Wed, 26 Oct 2022 07:46:13 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jean Delvare <jdelvare@...e.com>
Cc:     linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org
Subject: Re: [PATCH v3 9/9] rtc: isl12022: add support for temperature sensor

On 10/26/22 06:38, Rasmus Villemoes wrote:
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>

There should be some description above. Other than that,

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

 > ---
> v3: drop 0444 update_interval property.
> 
> v2 of patches 1-8 are already upstream (b1a1baa657c7 and parents).
> 
>   drivers/rtc/rtc-isl12022.c | 94 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 94 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
> index ca677c4265e6..a3b0de3393f5 100644
> --- a/drivers/rtc/rtc-isl12022.c
> +++ b/drivers/rtc/rtc-isl12022.c
> @@ -17,6 +17,7 @@
>   #include <linux/of.h>
>   #include <linux/of_device.h>
>   #include <linux/regmap.h>
> +#include <linux/hwmon.h>
>   
>   /* ISL register offsets */
>   #define ISL12022_REG_SC		0x00
> @@ -30,6 +31,9 @@
>   #define ISL12022_REG_SR		0x07
>   #define ISL12022_REG_INT	0x08
>   
> +#define ISL12022_REG_BETA	0x0d
> +#define ISL12022_REG_TEMP_L	0x28
> +
>   /* ISL register bits */
>   #define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
>   
> @@ -38,6 +42,7 @@
>   
>   #define ISL12022_INT_WRTC	(1 << 6)
>   
> +#define ISL12022_BETA_TSE	(1 << 7)
>   
>   static struct i2c_driver isl12022_driver;
>   
> @@ -46,6 +51,93 @@ struct isl12022 {
>   	struct regmap *regmap;
>   };
>   
> +static umode_t isl12022_hwmon_is_visible(const void *data,
> +					 enum hwmon_sensor_types type,
> +					 u32 attr, int channel)
> +{
> +	if (type == hwmon_temp && attr == hwmon_temp_input)
> +		return 0444;
> +
> +	return 0;
> +}
> +
> +/*
> + * A user-initiated temperature conversion is not started by this function,
> + * so the temperature is updated once every ~60 seconds.
> + */
> +static int isl12022_hwmon_read_temp(struct device *dev, long *mC)
> +{
> +	struct isl12022 *isl12022 = dev_get_drvdata(dev);
> +	struct regmap *regmap = isl12022->regmap;
> +	u8 temp_buf[2];
> +	int temp, ret;
> +
> +	ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L,
> +			       temp_buf, sizeof(temp_buf));
> +	if (ret)
> +		return ret;
> +	/*
> +	 * Temperature is represented as a 10-bit number, unit half-Kelvins.
> +	 */
> +	temp = (temp_buf[1] << 8) | temp_buf[0];
> +	temp *= 500;
> +	temp -= 273000;
> +
> +	*mC = temp;
> +
> +	return 0;
> +}
> +
> +static int isl12022_hwmon_read(struct device *dev,
> +			       enum hwmon_sensor_types type,
> +			       u32 attr, int channel, long *val)
> +{
> +	if (type == hwmon_temp && attr == hwmon_temp_input)
> +		return isl12022_hwmon_read_temp(dev, val);
> +
> +	return -EOPNOTSUPP;
> +}
> +
> +static const struct hwmon_channel_info *isl12022_hwmon_info[] = {
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
> +	NULL
> +};
> +
> +static const struct hwmon_ops isl12022_hwmon_ops = {
> +	.is_visible = isl12022_hwmon_is_visible,
> +	.read = isl12022_hwmon_read,
> +};
> +
> +static const struct hwmon_chip_info isl12022_hwmon_chip_info = {
> +	.ops = &isl12022_hwmon_ops,
> +	.info = isl12022_hwmon_info,
> +};
> +
> +static void isl12022_hwmon_register(struct device *dev)
> +{
> +	struct isl12022 *isl12022;
> +	struct device *hwmon;
> +	int ret;
> +
> +	if (!IS_REACHABLE(CONFIG_HWMON))
> +		return;
> +
> +	isl12022 = dev_get_drvdata(dev);
> +
> +	ret = regmap_update_bits(isl12022->regmap, ISL12022_REG_BETA,
> +				 ISL12022_BETA_TSE, ISL12022_BETA_TSE);
> +	if (ret) {
> +		dev_warn(dev, "unable to enable temperature sensor\n");
> +		return;
> +	}
> +
> +	hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", isl12022,
> +						     &isl12022_hwmon_chip_info,
> +						     NULL);
> +	if (IS_ERR(hwmon))
> +		dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);
> +}
> +
>   /*
>    * In the routines that deal directly with the isl12022 hardware, we use
>    * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
> @@ -160,6 +252,8 @@ static int isl12022_probe(struct i2c_client *client)
>   		return PTR_ERR(isl12022->regmap);
>   	}
>   
> +	isl12022_hwmon_register(&client->dev);
> +
>   	isl12022->rtc = devm_rtc_allocate_device(&client->dev);
>   	if (IS_ERR(isl12022->rtc))
>   		return PTR_ERR(isl12022->rtc);