Re: [PATCH 1/3] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[Guenter Roeck <linux@roeck-us.net>]

On 11/26/2016 09:15 PM, John Muir wrote:
> Add support for the TI TMP108 temperature sensor with some device
> configuration parameters.
>
> Signed-off-by: John Muir <john@jmuir.com>
> ---
>  Documentation/devicetree/bindings/hwmon/tmp108.txt |  27 ++
>  Documentation/hwmon/tmp108                         |  38 ++
>  drivers/hwmon/Kconfig                              |  11 +
>  drivers/hwmon/Makefile                             |   1 +
>  drivers/hwmon/tmp108.c                             | 429 +++++++++++++++++++++
>  5 files changed, 506 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
>  create mode 100644 Documentation/hwmon/tmp108
>  create mode 100644 drivers/hwmon/tmp108.c
>
> diff --git a/Documentation/devicetree/bindings/hwmon/tmp108.txt b/Documentation/devicetree/bindings/hwmon/tmp108.txt

This should be provided in a separate patch.

> new file mode 100644
> index 0000000..210af63
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/tmp108.txt
> @@ -0,0 +1,27 @@
> +TMP108 temperature sensor
> +-------------------------
> +
> +This device supports I2C only.
> +
> +Requires node properties:
> +- compatible : "ti,tmp108"
> +- reg : the I2C address of the device. This is 0x48, 0x49, 0x4a, or 0x4b.
> +
> +Optional node properties:
> +- ti,thermostat-mode-comparitor : (boolean) select the comparitor mode for the

s/comparitor/comparator/g

> +      thermostat rather than the default interrupt-mode.
> +- ti,alert-active-high : (boolean) make the alert pin active-high instead of
> +      the default active-low.

The driver doesn't support interrupts/alerts. Do those properties really add value ?

> +- ti,conversion-rate-cHz : (integer, cHz) select the conversion frequency for
> +      continuous mode, in centi-Hz: 25, 100 (default), 400, or 1600.
> +- ti,hysteresis : (integer, C) select the hysteresis value: 0, 1, 2, or 4
> +      (celcius).
> +
We would nor mally make the conversion rate and hysteresis user configurable,
with the update_interval and temp1_{min,max}_hyst attributes. Those are not really
system configuration properties.

> +Example:
> +	tmp108@48 {
> +		compatible = "ti,tmp108";
> +		reg = <0x48>;
> +		ti,alert-active-high;
> +		ti,hysteresis = <2>;
> +		ti,conversion-rate-cHz = <25>;
> +	};
> diff --git a/Documentation/hwmon/tmp108 b/Documentation/hwmon/tmp108
> new file mode 100644
> index 0000000..ef2e9a3
> --- /dev/null
> +++ b/Documentation/hwmon/tmp108
> @@ -0,0 +1,38 @@
> +Kernel driver tmp108
> +====================
> +
> +Supported chips:
> +  * Texas Instruments TMP108
> +    Prefix: 'tmp108'
> +    Addresses scanned: none
> +    Datasheet: http://www.ti.com/product/tmp108
> +
> +Author:
> +	John Muir <john@jmuir.com>
> +
> +Description
> +-----------
> +
> +The Texas Instruments TMP108 implements one temperature sensor. An alert pin
> +can be set when temperatures exceed minimum or maximum values plus or minus a
> +hysteresis value.
> +
> +The sensor is accurate to 0.75C over the range of -25 to +85 C, and to 1.0
> +degree from -40 to +125 C. Resolution of the sensor is 0.0625 degree. The
> +operating temperature has a minimum of -55 C and a maximum of +150 C.
> +Hysteresis values can be set to 0, 1, 2, or 4C.
> +
> +The TMP108 has a programmable update rate that can select between 8, 4, 1, and
> +0.5 Hz.
> +
> +By default the TMP108 reads the temperature continuously. To conserve power,
> +the TMP108 has a one-shot mode where the device is normally shut-down. When a
> +one shot is requested the temperature is read, the result can be retrieved,
> +and then the device is shut down automatically. (This driver only supports
> +continuous mode.)
> +
> +The driver provides the common sysfs-interface for temperatures (see
> +Documentation/hwmon/sysfs-interface under Temperatures).
> +
> +See Documentation/devicetree/bindings/hwmon/tmp108.txt for configuration
> +properties.
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 45cef3d..4c173de 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1591,6 +1591,17 @@ config SENSORS_TMP103
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called tmp103.
>
> +config SENSORS_TMP108
> +	tristate "Texas Instruments TMP108"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	  If you say yes here you get support for Texas Instruments TMP108
> +	  sensor chips.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called tmp108.
> +
>  config SENSORS_TMP401
>  	tristate "Texas Instruments TMP401 and compatibles"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index aecf4ba..51e5256 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -152,6 +152,7 @@ obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
>  obj-$(CONFIG_SENSORS_THMC50)	+= thmc50.o
>  obj-$(CONFIG_SENSORS_TMP102)	+= tmp102.o
>  obj-$(CONFIG_SENSORS_TMP103)	+= tmp103.o
> +obj-$(CONFIG_SENSORS_TMP108)	+= tmp108.o
>  obj-$(CONFIG_SENSORS_TMP401)	+= tmp401.o
>  obj-$(CONFIG_SENSORS_TMP421)	+= tmp421.o
>  obj-$(CONFIG_SENSORS_TWL4030_MADC)+= twl4030-madc-hwmon.o
> diff --git a/drivers/hwmon/tmp108.c b/drivers/hwmon/tmp108.c
> new file mode 100644
> index 0000000..da64517
> --- /dev/null
> +++ b/drivers/hwmon/tmp108.c
> @@ -0,0 +1,429 @@
> +/* Texas Instruments TMP108 SMBus temperature sensor driver
> + *
> + * Copyright (C) 2016 John Muir <john@jmuir.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +#include <linux/device.h>
> +#include <linux/jiffies.h>
> +#include <linux/regmap.h>
> +#include <linux/thermal.h>
> +#include <linux/of.h>
> +
Alphabetic order, please.

> +#define	DRIVER_NAME "tmp108"
> +
> +#define	TMP108_REG_TEMP		0x00
> +#define	TMP108_REG_CONF		0x01
> +#define	TMP108_REG_TLOW		0x02
> +#define	TMP108_REG_THIGH	0x03
> +
> +#define TMP108_TEMP_REG_COUNT	3
> +
> +#define TMP108_TEMP_MIN_MC	-50000 /* Minimum millicelcius. */
> +#define TMP108_TEMP_MAX_MC	127937 /* Maximum millicelcius. */
> +
> +/* Configuration register bits.
> + * Note: these bit definitions are byte swapped.
> + */
> +#define TMP108_CONF_M0		0x0100 /* Sensor mode. */
> +#define TMP108_CONF_M1		0x0200
> +#define TMP108_CONF_TM		0x0400 /* Thermostat mode. */
> +#define TMP108_CONF_FL		0x0800 /* Watchdog flag - TLOW */
> +#define TMP108_CONF_FH		0x1000 /* Watchdog flag - THIGH */
> +#define TMP108_CONF_CR0		0x2000 /* Conversion rate. */
> +#define TMP108_CONF_CR1		0x4000
> +#define TMP108_CONF_ID		0x8000
> +#define TMP108_CONF_HYS0	0x0010 /* Hysteresis. */
> +#define TMP108_CONF_HYS1	0x0020
> +#define TMP108_CONF_POL		0x0080 /* Polarity of alert. */
> +
> +/* Defaults set by the hardware upon reset. */
> +#define TMP108_CONF_DEFAULTS		(TMP108_CONF_CR0 | TMP108_CONF_TM |\
> +					 TMP108_CONF_HYS0 | TMP108_CONF_M1)
> +/* These bits are read-only. */
> +#define TMP108_CONF_READ_ONLY		(TMP108_CONF_FL | TMP108_CONF_FH |\
> +					 TMP108_CONF_ID)
> +
> +#define TMP108_CONF_MODE_MASK		(TMP108_CONF_M0|TMP108_CONF_M1)
> +#define TMP108_MODE_SHUTDOWN		0x0000
> +#define TMP108_MODE_ONE_SHOT		TMP108_CONF_M0
> +#define TMP108_MODE_CONTINUOUS		TMP108_CONF_M1		/* Default */
> +
> +#define TMP108_CONF_CONVRATE_MASK	(TMP108_CONF_CR0|TMP108_CONF_CR1)
> +#define TMP108_CONVRATE_0P25HZ		0x0000
> +#define TMP108_CONVRATE_1HZ		TMP108_CONF_CR0		/* Default */
> +#define TMP108_CONVRATE_4HZ		TMP108_CONF_CR1
> +#define TMP108_CONVRATE_16HZ		(TMP108_CONF_CR0|TMP108_CONF_CR1)
> +
> +#define TMP108_CONF_HYSTERESIS_MASK	(TMP108_CONF_HYS0|TMP108_CONF_HYS1)
> +#define TMP108_HYSTERESIS_0C		0x0000
> +#define TMP108_HYSTERESIS_1C		TMP108_CONF_HYS0	/* Default */
> +#define TMP108_HYSTERESIS_2C		TMP108_CONF_HYS1
> +#define TMP108_HYSTERESIS_4C		(TMP108_CONF_HYS0|TMP108_CONF_HYS1)
> +
> +#define TMP108_CONVERSION_TIME_MS	30	/* in milli-seconds */
> +
> +struct tmp108 {
> +	struct regmap *regmap;
> +	struct device *hwmon_dev;
> +	struct thermal_zone_device *tz;
> +	u16 config;
> +	unsigned long ready_time;
> +};
> +
> +static const u8 tmp108_temp_reg[TMP108_TEMP_REG_COUNT] = {
> +	TMP108_REG_TEMP,
> +	TMP108_REG_TLOW,
> +	TMP108_REG_THIGH,
> +};
> +
> +/* convert 12-bit TMP108 register value to milliCelsius */
> +static inline int tmp108_temp_reg_to_mC(s16 val)
> +{
> +	return (val & ~0x01) * 1000 / 256;
> +}
> +
> +/* convert milliCelsius to left adjusted 12-bit TMP108 register value */
> +static inline u16 tmp108_mC_to_temp_reg(int val)
> +{
> +	return (val * 256) / 1000;
> +}
> +
> +static int tmp108_read_reg_temp(struct device *dev, int reg, int *temp)
> +{
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +	unsigned int regval;
> +	int err;
> +
> +	switch (reg) {
> +	case TMP108_REG_TEMP:
> +		/* Is it too early to return a conversion ? */
> +		if (time_before(jiffies, tmp108->ready_time)) {
> +			dev_dbg(dev, "%s: Conversion not ready yet..\n",
> +				__func__);
> +			return -EAGAIN;
> +		}
> +		break;
> +	case TMP108_REG_TLOW:
> +	case TMP108_REG_THIGH:
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	err = regmap_read(tmp108->regmap, reg, &regval);
> +	if (err < 0)
> +		return err;
> +	*temp = tmp108_temp_reg_to_mC(regval);
> +
> +	return 0;
> +}
> +
> +static ssize_t tmp108_show_temp(struct device *dev,
> +				struct device_attribute *attr,
> +				char *buf)
> +{
> +	struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
> +	int temp;
> +	int err;
> +
> +	if (sda->index >= ARRAY_SIZE(tmp108_temp_reg))
> +		return -EINVAL;
> +
Unnecessary. That would be a programming error, which we don't check in the
kernel. You could also provide the register directly in sda->index.

> +	err = tmp108_read_reg_temp(dev, tmp108_temp_reg[sda->index], &temp);
> +	if (err)
> +		return err;
> +
> +	return snprintf(buf, PAGE_SIZE, "%d\n", temp);
> +}
> +
> +static ssize_t tmp108_set_temp(struct device *dev,
> +			       struct device_attribute *attr,
> +			       const char *buf, size_t count)
> +{
> +	struct sensor_device_attribute *sda = to_sensor_dev_attr(attr);
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +	long temp;
> +	int err;
> +
> +	if (sda->index >= ARRAY_SIZE(tmp108_temp_reg))
> +		return -EINVAL;
> +
> +	if (kstrtol(buf, 10, &temp) < 0)
> +		return -EINVAL;
> +
> +	temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
> +	err = regmap_write(tmp108->regmap, tmp108_temp_reg[sda->index],
> +			   tmp108_mC_to_temp_reg(temp));
> +	if (err)
> +		return err;
> +	return count;
> +}
> +
> +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, tmp108_show_temp, NULL, 0);
> +static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, tmp108_show_temp,
> +			  tmp108_set_temp, 1);
> +static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, tmp108_show_temp,
> +			  tmp108_set_temp, 2);
> +

You could also provide temp1_{min,max}_alarm.

> +static struct attribute *tmp108_attrs[] = {
> +	&sensor_dev_attr_temp1_input.dev_attr.attr,
> +	&sensor_dev_attr_temp1_min.dev_attr.attr,
> +	&sensor_dev_attr_temp1_max.dev_attr.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(tmp108);
> +
> +static int tmp108_get_temp(void *dev, int *temp)
> +{
> +	return tmp108_read_reg_temp(dev, TMP108_REG_TEMP, temp);
> +}
> +
> +static const struct thermal_zone_of_device_ops tmp108_of_thermal_ops = {
> +	.get_temp = tmp108_get_temp,
> +};
> +
> +static void tmp108_update_ready_time(struct tmp108 *tmp108)
> +{
> +	tmp108->ready_time = jiffies;
> +	if ((tmp108->config & TMP108_CONF_MODE_MASK)
> +	    == TMP108_MODE_CONTINUOUS) {

Don't you want a "!" here ? Presumably the delay is only needed
if the original configuration was not for continuous mode.

> +		tmp108->ready_time +=
> +			msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
> +	}
> +}
> +
> +static void tmp108_restore_config(void *data)
> +{
> +	struct tmp108 *tmp108 = data;
> +
> +	regmap_write(tmp108->regmap, TMP108_REG_CONF, tmp108->config);
> +	tmp108_update_ready_time(tmp108);

This is called when the driver is unloaded, meaning the call to
tmp108_update_ready_time() does not really add any value.

> +}
> +
> +static bool tmp108_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	return reg != TMP108_REG_TEMP;
> +}
> +
> +static bool tmp108_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	return reg == TMP108_REG_TEMP;
> +}
> +
> +static const struct regmap_config tmp108_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 16,
> +	.max_register = TMP108_REG_THIGH,
> +	.writeable_reg = tmp108_is_writeable_reg,
> +	.volatile_reg = tmp108_is_volatile_reg,
> +	.val_format_endian = REGMAP_ENDIAN_BIG,
> +	.cache_type = REGCACHE_RBTREE,
> +	.use_single_rw = true,
> +};
> +
> +static int tmp108_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct device *hwmon_dev;
> +	struct tmp108 *tmp108;
> +	unsigned int regval;
> +	int err;
> +	u16 config;
> +	u32 convrate = 100;
> +	u32 hysteresis = 1;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_WORD_DATA)) {
> +		dev_err(dev,
> +			"adapter doesn't support SMBus word transactions\n");
> +		return -ENODEV;
> +	}
> +
> +	tmp108 = devm_kzalloc(dev, sizeof(*tmp108), GFP_KERNEL);
> +	if (!tmp108)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, tmp108);
> +
> +	tmp108->regmap = devm_regmap_init_i2c(client, &tmp108_regmap_config);
> +	if (IS_ERR(tmp108->regmap))
> +		return PTR_ERR(tmp108->regmap);
> +
> +	err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
> +	if (err < 0) {
> +		dev_err(dev, "error reading config register\n");
> +		return err;
> +	}
> +	tmp108->config = regval;
> +	config = regval;
> +
> +	/* At this time, only continuous mode is supported. */
> +	config &= ~TMP108_CONF_MODE_MASK;
> +	config |= TMP108_MODE_CONTINUOUS;
> +
> +	if (device_property_read_bool(dev, "ti,thermostat-mode-comparitor"))
> +		config &= ~TMP108_CONF_TM;
> +	else
> +		config |= TMP108_CONF_TM;
> +
> +	if (device_property_read_bool(dev, "ti,alert-active-high"))
> +		config |= TMP108_CONF_POL;
> +	else
> +		config &= ~TMP108_CONF_POL;
> +
> +	if (device_property_read_u32(dev, "ti,conversion-rate-cHz", &convrate)
> +	    >= 0) {
> +		config &= ~TMP108_CONF_CONVRATE_MASK;
> +		switch (convrate) {
> +		case 25:
> +			config |= TMP108_CONVRATE_0P25HZ;
> +			break;
> +		case 100:
> +			config |= TMP108_CONVRATE_1HZ;
> +			break;
> +		case 400:
> +			config |= TMP108_CONVRATE_4HZ;
> +			break;
> +		case 1600:
> +			config |= TMP108_CONVRATE_16HZ;
> +			break;
> +		default:
> +			dev_err(dev, "conversion rate %u invalid: defaulting to 1Hz.\n",
> +				convrate);
> +			convrate = 100;
> +			config |= TMP108_CONVRATE_1HZ;
> +			break;
> +		}
> +	}
> +
> +	if (device_property_read_u32(dev, "ti,hysteresis", &hysteresis) >= 0) {
> +		config &= ~TMP108_CONF_HYSTERESIS_MASK;
> +		switch (hysteresis) {
> +		case 0:
> +			config |= TMP108_HYSTERESIS_0C;
> +			break;
> +		case 1:
> +			config |= TMP108_HYSTERESIS_1C;
> +			break;
> +		case 2:
> +			config |= TMP108_HYSTERESIS_2C;
> +			break;
> +		case 4:
> +			config |= TMP108_HYSTERESIS_4C;
> +			break;
> +		default:
> +			dev_err(dev, "hysteresis value %u invalid: defaulting to 1C.\n",
> +				hysteresis);
> +			hysteresis = 1;
> +			config |= TMP108_HYSTERESIS_1C;
> +			break;
> +		}
> +	}
> +
> +	err = regmap_write(tmp108->regmap, TMP108_REG_CONF, config);
> +	if (err < 0) {
> +		dev_err(dev, "error writing config register\n");
> +		return err;
> +	}
> +
> +	tmp108->config = config;
> +	tmp108_update_ready_time(tmp108);
> +
> +	err = devm_add_action_or_reset(dev, tmp108_restore_config, tmp108);
> +	if (err)
> +		return err;
> +
> +	hwmon_dev = hwmon_device_register_with_groups(dev, client->name,
> +						      tmp108, tmp108_groups);

Please consider using the devm_ function here.

> +	if (IS_ERR(hwmon_dev)) {
> +		dev_dbg(dev, "unable to register hwmon device\n");
> +		return PTR_ERR(hwmon_dev);
> +	}
> +
> +	tmp108->hwmon_dev = hwmon_dev;
> +	tmp108->tz = thermal_zone_of_sensor_register(hwmon_dev, 0, hwmon_dev,
> +						     &tmp108_of_thermal_ops);
> +	if (IS_ERR(tmp108->tz))
> +		return PTR_ERR(tmp108->tz);

hwmon device not unregistered here. That would be fixed by using the devm
function above.

> +
> +	dev_info(dev, "%s, alert: active %s, hyst: %uC, conv: %ucHz\n",
> +		 (tmp108->config & TMP108_CONF_TM) != 0 ?
> +			"interrupt" : "comparator",
> +		 (tmp108->config & TMP108_CONF_POL) != 0 ? "high" : "low",
> +		 hysteresis, convrate);
> +	return 0;
> +}
> +
> +static int tmp108_remove(struct i2c_client *client)
> +{
> +	struct tmp108 *tmp108 = i2c_get_clientdata(client);
> +
> +	thermal_zone_of_sensor_unregister(tmp108->hwmon_dev, tmp108->tz);
> +	hwmon_device_unregister(tmp108->hwmon_dev);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int tmp108_suspend(struct device *dev)

I prefer __maybe_unused without #ifdef to ensure that the functions can be compiled
even if unused.

> +{
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +
> +	return regmap_update_bits(tmp108->regmap, TMP108_REG_CONF,
> +				  TMP108_CONF_MODE_MASK, TMP108_MODE_SHUTDOWN);
> +}
> +
> +static int tmp108_resume(struct device *dev)
> +{
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +	int err;
> +
> +	err = regmap_write(tmp108->regmap, TMP108_REG_CONF, tmp108->config);
> +
> +	tmp108_update_ready_time(tmp108);
> +
> +	return err;
> +}
> +#endif /* CONFIG_PM */
> +
> +static SIMPLE_DEV_PM_OPS(tmp108_dev_pm_ops, tmp108_suspend, tmp108_resume);
> +
> +static const struct i2c_device_id tmp108_id[] = {
> +	{ "tmp108", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, tmp108_id);
> +
> +static struct i2c_driver tmp108_driver = {
> +	.driver.name	= DRIVER_NAME,
> +	.driver.pm	= &tmp108_dev_pm_ops,
> +	.probe		= tmp108_probe,
> +	.remove		= tmp108_remove,
> +	.id_table	= tmp108_id,
> +};
> +
> +module_i2c_driver(tmp108_driver);
> +
> +MODULE_AUTHOR("John Muir <john@jmuir.com>");
> +MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
> +MODULE_LICENSE("GPL");
>