[PATCH 0/3] Texas Instruments TMP108 temperature sensor driver.

[PATCH 0/3] Texas Instruments TMP108 temperature sensor driver.

[John Muir]

This driver is split into three patches as it is being ported forward from
a Linux 4.4 implementation where it was tested. The final driver code uses
interfaces that are not available in 4.4.

John Muir (3):
  hwmon: Add Texas Instruments TMP108 temperature sensor driver.
  hwmon: tmp108: Use devm variants of registration interfaces.
  hwmon: tmp108: Update driver to use hwmon_chip_info.

 Documentation/devicetree/bindings/hwmon/tmp108.txt |  27 ++
 Documentation/hwmon/tmp108                         |  38 ++
 drivers/hwmon/Kconfig                              |  11 +
 drivers/hwmon/Makefile                             |   1 +
 drivers/hwmon/tmp108.c                             | 421 +++++++++++++++++++++
 5 files changed, 498 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
 create mode 100644 Documentation/hwmon/tmp108
 create mode 100644 drivers/hwmon/tmp108.c

-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH 0/3] Texas Instruments TMP108 temperature sensor driver.

[Guenter Roeck]

On 11/26/2016 05:26 PM, John Muir wrote:
> This driver is split into three patches as it is being ported forward from
> a Linux 4.4 implementation where it was tested. The final driver code uses
> interfaces that are not available in 4.4.
>
> John Muir (3):
>   hwmon: Add Texas Instruments TMP108 temperature sensor driver.
>   hwmon: tmp108: Use devm variants of registration interfaces.
>   hwmon: tmp108: Update driver to use hwmon_chip_info.
>
>  Documentation/devicetree/bindings/hwmon/tmp108.txt |  27 ++
>  Documentation/hwmon/tmp108                         |  38 ++
>  drivers/hwmon/Kconfig                              |  11 +
>  drivers/hwmon/Makefile                             |   1 +
>  drivers/hwmon/tmp108.c                             | 421 +++++++++++++++++++++
>  5 files changed, 498 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
>  create mode 100644 Documentation/hwmon/tmp108
>  create mode 100644 drivers/hwmon/tmp108.c
>

Hi John,

maybe the rest of the patches are delayed, but so far I only see this introduction.
Just an early note, in case the other patches still show up.

Can you send me a register dump for this chip ?

Thanks,
Guenter

[PATCH v2 0/2] Texas Instruments TMP108 temperature sensor driver.

[John Muir]

This adds a device driver for the Texas Instruments TMP108 temperature
sensor. The driver provides support to read the temperature, read or modify
the update interval, min and max temperature and hysteresis values, as well
as read current alarm status. Support for alarm interrupts will come in a
future patch.

John Muir (2):
  hwmon: Add Texas Instruments TMP108 temperature sensor driver.
  devicetree: hwmon: Add documentation for TMP108 driver.

 Documentation/devicetree/bindings/hwmon/tmp108.txt |  24 +
 Documentation/hwmon/tmp108                         |  38 ++
 drivers/hwmon/Kconfig                              |  11 +
 drivers/hwmon/Makefile                             |   1 +
 drivers/hwmon/tmp108.c                             | 495 +++++++++++++++++++++
 5 files changed, 569 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
 create mode 100644 Documentation/hwmon/tmp108
 create mode 100644 drivers/hwmon/tmp108.c

-- 
2.8.0.rc3.226.g39d4020

[PATCH 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[John Muir]

Add support for the TI TMP108 temperature sensor with some device
configuration parameters.

Signed-off-by: John Muir <john@jmuir.com>
---
 Documentation/hwmon/tmp108 |  38 ++++
 drivers/hwmon/Kconfig      |  11 +
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/tmp108.c     | 495 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 545 insertions(+)
 create mode 100644 Documentation/hwmon/tmp108
 create mode 100644 drivers/hwmon/tmp108.c

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..35d598d
--- /dev/null
+++ b/drivers/hwmon/tmp108.c
@@ -0,0 +1,495 @@
+/* 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/device.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#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_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 */
+					/* When M1 is set, M0 is ignored. */
+
+#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;
+	u16 orig_config;
+	u16 curr_config;
+	unsigned long ready_time;
+};
+
+/* 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(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *temp)
+{
+	struct tmp108 *tmp108 = dev_get_drvdata(dev);
+	unsigned int regval;
+	int err, hyst;
+
+	if (type == hwmon_chip) {
+		if (attr == hwmon_chip_update_interval) {
+			err = regmap_read(tmp108->regmap, TMP108_REG_CONF,
+					  &regval);
+			if (err < 0)
+				return err;
+			switch (regval & TMP108_CONF_CONVRATE_MASK) {
+			case TMP108_CONVRATE_0P25HZ:
+			default:
+				*temp = 4000;
+				break;
+			case TMP108_CONVRATE_1HZ:
+				*temp = 1000;
+				break;
+			case TMP108_CONVRATE_4HZ:
+				*temp = 250;
+				break;
+			case TMP108_CONVRATE_16HZ:
+				*temp = 63;
+				break;
+			}
+			return 0;
+		}
+		return -EOPNOTSUPP;
+	}
+
+	switch (attr) {
+	case hwmon_temp_input:
+		/* 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;
+		}
+		err = regmap_read(tmp108->regmap, TMP108_REG_TEMP, &regval);
+		if (err < 0)
+			return err;
+		*temp = tmp108_temp_reg_to_mC(regval);
+		break;
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+		err = regmap_read(tmp108->regmap, attr == hwmon_temp_min ?
+				  TMP108_REG_TLOW : TMP108_REG_THIGH, &regval);
+		if (err < 0)
+			return err;
+		*temp = tmp108_temp_reg_to_mC(regval);
+		break;
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+		err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
+		if (err < 0)
+			return err;
+		*temp = !!(regval & (attr == hwmon_temp_min_alarm ?
+				     TMP108_CONF_FL : TMP108_CONF_FH));
+		break;
+	case hwmon_temp_min_hyst:
+	case hwmon_temp_max_hyst:
+		err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
+		if (err < 0)
+			return err;
+		switch (regval & TMP108_CONF_HYSTERESIS_MASK) {
+		case TMP108_HYSTERESIS_0C:
+		default:
+			hyst = 0;
+			break;
+		case TMP108_HYSTERESIS_1C:
+			hyst = 1000;
+			break;
+		case TMP108_HYSTERESIS_2C:
+			hyst = 2000;
+			break;
+		case TMP108_HYSTERESIS_4C:
+			hyst = 4000;
+			break;
+		}
+		err = regmap_read(tmp108->regmap, attr == hwmon_temp_min_hyst ?
+				  TMP108_REG_TLOW : TMP108_REG_THIGH, &regval);
+		if (err < 0)
+			return err;
+		*temp = tmp108_temp_reg_to_mC(regval);
+		if (attr == hwmon_temp_min_hyst)
+			*temp += hyst;
+		else
+			*temp -= hyst;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int tmp108_write(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long temp)
+{
+	struct tmp108 *tmp108 = dev_get_drvdata(dev);
+	u32 regval, mask;
+	int err;
+
+	if (type == hwmon_chip) {
+		if (attr == hwmon_chip_update_interval) {
+			if (temp < 156)
+				mask = TMP108_CONVRATE_16HZ;
+			else if (temp < 625)
+				mask = TMP108_CONVRATE_4HZ;
+			else if (temp < 2500)
+				mask = TMP108_CONVRATE_1HZ;
+			else
+				mask = TMP108_CONVRATE_0P25HZ;
+			err = regmap_update_bits(tmp108->regmap,
+						 TMP108_REG_CONF,
+						 TMP108_CONF_CONVRATE_MASK,
+						 mask);
+			if (err)
+				return err;
+			tmp108->curr_config &= ~TMP108_CONF_CONVRATE_MASK;
+			tmp108->curr_config |= mask;
+			return 0;
+		}
+		return -EOPNOTSUPP;
+	}
+
+	switch (attr) {
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+		temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
+		return regmap_write(tmp108->regmap,
+				    attr == hwmon_temp_min ?
+					TMP108_REG_TLOW : TMP108_REG_THIGH,
+				    tmp108_mC_to_temp_reg(temp));
+	case hwmon_temp_min_hyst:
+	case hwmon_temp_max_hyst:
+		temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
+		err = regmap_read(tmp108->regmap,
+				  attr == hwmon_temp_min_hyst ?
+					TMP108_REG_TLOW : TMP108_REG_THIGH,
+				  &regval);
+		if (err < 0)
+			return err;
+		if (attr == hwmon_temp_min_hyst)
+			temp -= tmp108_temp_reg_to_mC(regval);
+		else
+			temp = tmp108_temp_reg_to_mC(regval) - temp;
+		if (temp < 500)
+			mask = TMP108_HYSTERESIS_0C;
+		else if (temp < 1500)
+			mask = TMP108_HYSTERESIS_1C;
+		else if (temp < 3000)
+			mask = TMP108_HYSTERESIS_2C;
+		else
+			mask = TMP108_HYSTERESIS_4C;
+		err = regmap_update_bits(tmp108->regmap, TMP108_REG_CONF,
+					 TMP108_CONF_HYSTERESIS_MASK,
+					 mask);
+		if (err)
+			return err;
+		tmp108->curr_config &= ~TMP108_CONF_HYSTERESIS_MASK;
+		tmp108->curr_config |= mask;
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t tmp108_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	if (type == hwmon_chip && attr == hwmon_chip_update_interval)
+		return 0644;
+
+	if (type != hwmon_temp)
+		return 0;
+
+	switch (attr) {
+	case hwmon_temp_input:
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+		return 0444;
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+	case hwmon_temp_min_hyst:
+	case hwmon_temp_max_hyst:
+		return 0644;
+	default:
+		return 0;
+	}
+}
+
+static u32 tmp108_chip_config[] = {
+	HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL,
+	0
+};
+
+static const struct hwmon_channel_info tmp108_chip = {
+	.type = hwmon_chip,
+	.config = tmp108_chip_config,
+};
+
+static u32 tmp108_temp_config[] = {
+	HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN | HWMON_T_MIN_HYST
+		| HWMON_T_MAX_HYST | HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
+	0
+};
+
+static const struct hwmon_channel_info tmp108_temp = {
+	.type = hwmon_temp,
+	.config = tmp108_temp_config,
+};
+
+static const struct hwmon_channel_info *tmp108_info[] = {
+	&tmp108_chip,
+	&tmp108_temp,
+	NULL
+};
+
+static const struct hwmon_ops tmp108_hwmon_ops = {
+	.is_visible = tmp108_is_visible,
+	.read = tmp108_read,
+	.write = tmp108_write,
+};
+
+static const struct hwmon_chip_info tmp108_chip_info = {
+	.ops = &tmp108_hwmon_ops,
+	.info = tmp108_info,
+};
+
+static void tmp108_restore_config(void *data)
+{
+	struct tmp108 *tmp108 = data;
+
+	regmap_write(tmp108->regmap, TMP108_REG_CONF, tmp108->orig_config);
+}
+
+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)
+{
+	/* Configuration register must be volatile to enable FL and FH. */
+	return reg == TMP108_REG_TEMP || reg == TMP108_REG_CONF;
+}
+
+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;
+
+	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;
+
+	dev_set_drvdata(dev, tmp108);
+
+	tmp108->regmap = devm_regmap_init_i2c(client, &tmp108_regmap_config);
+	if (IS_ERR(tmp108->regmap)) {
+		err = PTR_ERR(tmp108->regmap);
+		dev_err(dev, "regmap init failed: %d", err);
+		return err;
+	}
+
+	err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
+	if (err < 0) {
+		dev_err(dev, "error reading config register: %d", err);
+		return err;
+	}
+	tmp108->orig_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-comparator"))
+		config &= ~TMP108_CONF_TM;
+	else
+		config |= TMP108_CONF_TM;
+
+	err = regmap_write(tmp108->regmap, TMP108_REG_CONF, config);
+	if (err < 0) {
+		dev_err(dev, "error writing config register: %d", err);
+		return err;
+	}
+
+	tmp108->curr_config = config;
+	tmp108->ready_time = jiffies;
+	if ((tmp108->orig_config & TMP108_CONF_MODE_MASK) ==
+	    TMP108_MODE_SHUTDOWN)
+		tmp108->ready_time +=
+			msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
+
+	err = devm_add_action_or_reset(dev, tmp108_restore_config, tmp108);
+	if (err) {
+		dev_err(dev, "add action or reset failed: %d", err);
+		return err;
+	}
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 tmp108,
+							 &tmp108_chip_info,
+							 NULL);
+	if (IS_ERR(hwmon_dev)) {
+		err = PTR_ERR(hwmon_dev);
+		dev_err(dev, "unable to register hwmon device: %d", err);
+		return err;
+	}
+
+	dev_info(dev, "%s\n",
+		 (config & TMP108_CONF_TM) != 0 ? "interrupt" : "comparator");
+	return 0;
+}
+
+static int __maybe_unused tmp108_suspend(struct device *dev)
+{
+	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 __maybe_unused tmp108_resume(struct device *dev)
+{
+	struct tmp108 *tmp108 = dev_get_drvdata(dev);
+	int err;
+
+	err = regmap_write(tmp108->regmap, TMP108_REG_CONF,
+			   tmp108->curr_config);
+
+	tmp108->ready_time = jiffies;
+	if (tmp108->curr_config & TMP108_MODE_CONTINUOUS)
+		tmp108->ready_time +=
+			msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
+
+	return err;
+}
+
+static SIMPLE_DEV_PM_OPS(tmp108_dev_pm_ops, tmp108_suspend, tmp108_resume);
+
+static const struct i2c_device_id tmp108_i2c_ids[] = {
+	{ "tmp108", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tmp108_i2c_ids);
+
+#ifdef CONFIG_OF
+static const struct of_device_id tmp108_of_ids[] = {
+	{ .compatible = "ti,tmp108", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, tmp108_of_ids);
+#endif
+
+static struct i2c_driver tmp108_driver = {
+	.driver.name	= DRIVER_NAME,
+	.driver.pm	= &tmp108_dev_pm_ops,
+	.probe		= tmp108_probe,
+	.id_table	= tmp108_i2c_ids,
+};
+
+module_i2c_driver(tmp108_driver);
+
+MODULE_AUTHOR("John Muir <john@jmuir.com>");
+MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[Guenter Roeck]

Hi John,

On 11/30/2016 12:36 PM, John Muir wrote:
> Add support for the TI TMP108 temperature sensor with some device
> configuration parameters.
>

Overall looks pretty good. Just a couple of nitpicks.

Thanks,
Guenter

> Signed-off-by: John Muir <john@jmuir.com>
> ---
>  Documentation/hwmon/tmp108 |  38 ++++
>  drivers/hwmon/Kconfig      |  11 +
>  drivers/hwmon/Makefile     |   1 +
>  drivers/hwmon/tmp108.c     | 495 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 545 insertions(+)
>  create mode 100644 Documentation/hwmon/tmp108
>  create mode 100644 drivers/hwmon/tmp108.c
>
> 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..35d598d
> --- /dev/null
> +++ b/drivers/hwmon/tmp108.c
> @@ -0,0 +1,495 @@
> +/* 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/device.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/jiffies.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +#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_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 */
> +					/* When M1 is set, M0 is ignored. */
> +
> +#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;
> +	u16 orig_config;
> +	u16 curr_config;
> +	unsigned long ready_time;
> +};
> +
> +/* convert 12-bit TMP108 register value to milliCelsius */
> +static inline int tmp108_temp_reg_to_mC(s16 val)
> +{
> +	return (val & ~0x01) * 1000 / 256;

Why ~0x01 and not ~0x0f ? The lower 4 bits are supposed to be 0.

> +}
> +
> +/* 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(struct device *dev, enum hwmon_sensor_types type,
> +		       u32 attr, int channel, long *temp)
> +{
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +	unsigned int regval;
> +	int err, hyst;
> +
> +	if (type == hwmon_chip) {
> +		if (attr == hwmon_chip_update_interval) {
> +			err = regmap_read(tmp108->regmap, TMP108_REG_CONF,
> +					  &regval);
> +			if (err < 0)
> +				return err;
> +			switch (regval & TMP108_CONF_CONVRATE_MASK) {
> +			case TMP108_CONVRATE_0P25HZ:
> +			default:
> +				*temp = 4000;
> +				break;
> +			case TMP108_CONVRATE_1HZ:
> +				*temp = 1000;
> +				break;
> +			case TMP108_CONVRATE_4HZ:
> +				*temp = 250;
> +				break;
> +			case TMP108_CONVRATE_16HZ:
> +				*temp = 63;
> +				break;
> +			}
> +			return 0;
> +		}
> +		return -EOPNOTSUPP;
> +	}
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +		/* 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;
> +		}
> +		err = regmap_read(tmp108->regmap, TMP108_REG_TEMP, &regval);
> +		if (err < 0)
> +			return err;
> +		*temp = tmp108_temp_reg_to_mC(regval);
> +		break;
> +	case hwmon_temp_min:
> +	case hwmon_temp_max:
> +		err = regmap_read(tmp108->regmap, attr == hwmon_temp_min ?
> +				  TMP108_REG_TLOW : TMP108_REG_THIGH, &regval);
> +		if (err < 0)
> +			return err;
> +		*temp = tmp108_temp_reg_to_mC(regval);
> +		break;
> +	case hwmon_temp_min_alarm:
> +	case hwmon_temp_max_alarm:
> +		err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
> +		if (err < 0)
> +			return err;
> +		*temp = !!(regval & (attr == hwmon_temp_min_alarm ?
> +				     TMP108_CONF_FL : TMP108_CONF_FH));
> +		break;
> +	case hwmon_temp_min_hyst:
> +	case hwmon_temp_max_hyst:
> +		err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
> +		if (err < 0)
> +			return err;
> +		switch (regval & TMP108_CONF_HYSTERESIS_MASK) {
> +		case TMP108_HYSTERESIS_0C:
> +		default:
> +			hyst = 0;
> +			break;
> +		case TMP108_HYSTERESIS_1C:
> +			hyst = 1000;
> +			break;
> +		case TMP108_HYSTERESIS_2C:
> +			hyst = 2000;
> +			break;
> +		case TMP108_HYSTERESIS_4C:
> +			hyst = 4000;
> +			break;
> +		}
> +		err = regmap_read(tmp108->regmap, attr == hwmon_temp_min_hyst ?
> +				  TMP108_REG_TLOW : TMP108_REG_THIGH, &regval);
> +		if (err < 0)
> +			return err;
> +		*temp = tmp108_temp_reg_to_mC(regval);
> +		if (attr == hwmon_temp_min_hyst)
> +			*temp += hyst;
> +		else
> +			*temp -= hyst;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int tmp108_write(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long temp)
> +{
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +	u32 regval, mask;
> +	int err;
> +
> +	if (type == hwmon_chip) {
> +		if (attr == hwmon_chip_update_interval) {
> +			if (temp < 156)
> +				mask = TMP108_CONVRATE_16HZ;
> +			else if (temp < 625)
> +				mask = TMP108_CONVRATE_4HZ;
> +			else if (temp < 2500)
> +				mask = TMP108_CONVRATE_1HZ;
> +			else
> +				mask = TMP108_CONVRATE_0P25HZ;
> +			err = regmap_update_bits(tmp108->regmap,
> +						 TMP108_REG_CONF,
> +						 TMP108_CONF_CONVRATE_MASK,
> +						 mask);
> +			if (err)
> +				return err;
> +			tmp108->curr_config &= ~TMP108_CONF_CONVRATE_MASK;
> +			tmp108->curr_config |= mask;
> +			return 0;
> +		}
> +		return -EOPNOTSUPP;
> +	}
> +
> +	switch (attr) {
> +	case hwmon_temp_min:
> +	case hwmon_temp_max:
> +		temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
> +		return regmap_write(tmp108->regmap,
> +				    attr == hwmon_temp_min ?
> +					TMP108_REG_TLOW : TMP108_REG_THIGH,
> +				    tmp108_mC_to_temp_reg(temp));
> +	case hwmon_temp_min_hyst:
> +	case hwmon_temp_max_hyst:
> +		temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
> +		err = regmap_read(tmp108->regmap,
> +				  attr == hwmon_temp_min_hyst ?
> +					TMP108_REG_TLOW : TMP108_REG_THIGH,
> +				  &regval);
> +		if (err < 0)
> +			return err;
> +		if (attr == hwmon_temp_min_hyst)
> +			temp -= tmp108_temp_reg_to_mC(regval);
> +		else
> +			temp = tmp108_temp_reg_to_mC(regval) - temp;
> +		if (temp < 500)
> +			mask = TMP108_HYSTERESIS_0C;
> +		else if (temp < 1500)
> +			mask = TMP108_HYSTERESIS_1C;
> +		else if (temp < 3000)
> +			mask = TMP108_HYSTERESIS_2C;
> +		else
> +			mask = TMP108_HYSTERESIS_4C;
> +		err = regmap_update_bits(tmp108->regmap, TMP108_REG_CONF,
> +					 TMP108_CONF_HYSTERESIS_MASK,
> +					 mask);
> +		if (err)
> +			return err;
> +		tmp108->curr_config &= ~TMP108_CONF_HYSTERESIS_MASK;
> +		tmp108->curr_config |= mask;
> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static umode_t tmp108_is_visible(const void *data, enum hwmon_sensor_types type,
> +				 u32 attr, int channel)
> +{
> +	if (type == hwmon_chip && attr == hwmon_chip_update_interval)
> +		return 0644;
> +
> +	if (type != hwmon_temp)
> +		return 0;
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +	case hwmon_temp_min_alarm:
> +	case hwmon_temp_max_alarm:
> +		return 0444;
> +	case hwmon_temp_min:
> +	case hwmon_temp_max:
> +	case hwmon_temp_min_hyst:
> +	case hwmon_temp_max_hyst:
> +		return 0644;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static u32 tmp108_chip_config[] = {
> +	HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL,
> +	0
> +};
> +
> +static const struct hwmon_channel_info tmp108_chip = {
> +	.type = hwmon_chip,
> +	.config = tmp108_chip_config,
> +};
> +
> +static u32 tmp108_temp_config[] = {
> +	HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN | HWMON_T_MIN_HYST
> +		| HWMON_T_MAX_HYST | HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
> +	0
> +};
> +
> +static const struct hwmon_channel_info tmp108_temp = {
> +	.type = hwmon_temp,
> +	.config = tmp108_temp_config,
> +};
> +
> +static const struct hwmon_channel_info *tmp108_info[] = {
> +	&tmp108_chip,
> +	&tmp108_temp,
> +	NULL
> +};
> +
> +static const struct hwmon_ops tmp108_hwmon_ops = {
> +	.is_visible = tmp108_is_visible,
> +	.read = tmp108_read,
> +	.write = tmp108_write,
> +};
> +
> +static const struct hwmon_chip_info tmp108_chip_info = {
> +	.ops = &tmp108_hwmon_ops,
> +	.info = tmp108_info,
> +};
> +
> +static void tmp108_restore_config(void *data)
> +{
> +	struct tmp108 *tmp108 = data;
> +
> +	regmap_write(tmp108->regmap, TMP108_REG_CONF, tmp108->orig_config);
> +}
> +
> +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)
> +{
> +	/* Configuration register must be volatile to enable FL and FH. */
> +	return reg == TMP108_REG_TEMP || reg == TMP108_REG_CONF;
> +}
> +
> +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;
> +
> +	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;
> +
> +	dev_set_drvdata(dev, tmp108);
> +
> +	tmp108->regmap = devm_regmap_init_i2c(client, &tmp108_regmap_config);
> +	if (IS_ERR(tmp108->regmap)) {
> +		err = PTR_ERR(tmp108->regmap);
> +		dev_err(dev, "regmap init failed: %d", err);
> +		return err;
> +	}
> +
> +	err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
> +	if (err < 0) {
> +		dev_err(dev, "error reading config register: %d", err);
> +		return err;
> +	}
> +	tmp108->orig_config = regval;
> +	config = regval;
> +

Nitpick, but a separate 'regval' variable is not really necessary.
Just make config an u32 and use it directly (this actually makes the code
more efficient on many architectures, since cpu registers tend to be
at least 32 bit wide and 16 bit accesses result in extra masking).

> +	/* 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-comparator"))
> +		config &= ~TMP108_CONF_TM;
> +	else
> +		config |= TMP108_CONF_TM;
> +
As suggested separately, I would suggest to drop this and always select comparator mode.

> +	err = regmap_write(tmp108->regmap, TMP108_REG_CONF, config);
> +	if (err < 0) {
> +		dev_err(dev, "error writing config register: %d", err);
> +		return err;
> +	}
> +
> +	tmp108->curr_config = config;
> +	tmp108->ready_time = jiffies;
> +	if ((tmp108->orig_config & TMP108_CONF_MODE_MASK) ==
> +	    TMP108_MODE_SHUTDOWN)
> +		tmp108->ready_time +=
> +			msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
> +
> +	err = devm_add_action_or_reset(dev, tmp108_restore_config, tmp108);
> +	if (err) {
> +		dev_err(dev, "add action or reset failed: %d", err);
> +		return err;
> +	}
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
> +							 tmp108,
> +							 &tmp108_chip_info,
> +							 NULL);
> +	if (IS_ERR(hwmon_dev)) {
> +		err = PTR_ERR(hwmon_dev);
> +		dev_err(dev, "unable to register hwmon device: %d", err);
> +		return err;
> +	}

This message does not add real value. The return value will be -EINVAL,
indicating a programming error which should be fixed before the driver
is submitted, or -ENOMEM, which will be logged separately.

> +
> +	dev_info(dev, "%s\n",
> +		 (config & TMP108_CONF_TM) != 0 ? "interrupt" : "comparator");

Does it really add value to tell this to the user ? A text such as "<device>: interrupt"
or "<device>: comparator" may tell you something, but anyone else will just be confused.
Did the device get an interrupt ? Was that bad ? Did it compare something ? What ? Why ?

Overall I prefer a simeple
	return PTR_ERR_OR_ZERO(hwmon_dev);

> +	return 0;
> +}
> +
> +static int __maybe_unused tmp108_suspend(struct device *dev)
> +{
> +	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 __maybe_unused tmp108_resume(struct device *dev)
> +{
> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> +	int err;
> +
> +	err = regmap_write(tmp108->regmap, TMP108_REG_CONF,
> +			   tmp108->curr_config);
> +
> +	tmp108->ready_time = jiffies;
> +	if (tmp108->curr_config & TMP108_MODE_CONTINUOUS)

Since only continuous mode is supported, and it is somewhat unlikely
that we'll ever support one-shot mode, I think it would be better to
unconditionally set continuous mode and the delay here and drop
curr_config entirely. curr_config adds quite some complexity to the
driver with no real gain.

> +		tmp108->ready_time +=
> +			msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
> +
> +	return err;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(tmp108_dev_pm_ops, tmp108_suspend, tmp108_resume);
> +
> +static const struct i2c_device_id tmp108_i2c_ids[] = {
> +	{ "tmp108", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, tmp108_i2c_ids);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id tmp108_of_ids[] = {
> +	{ .compatible = "ti,tmp108", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, tmp108_of_ids);
> +#endif
> +
> +static struct i2c_driver tmp108_driver = {
> +	.driver.name	= DRIVER_NAME,
> +	.driver.pm	= &tmp108_dev_pm_ops,
> +	.probe		= tmp108_probe,
> +	.id_table	= tmp108_i2c_ids,
> +};
> +
> +module_i2c_driver(tmp108_driver);
> +
> +MODULE_AUTHOR("John Muir <john@jmuir.com>");
> +MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
> +MODULE_LICENSE("GPL");
>

Re: [PATCH 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[John Muir]

Hi Guenter,

On Dec 1, 2016, at 7:19 AM, Guenter Roeck <linux@roeck-us.net> wrote:
> 
>> +/* convert 12-bit TMP108 register value to milliCelsius */
>> +static inline int tmp108_temp_reg_to_mC(s16 val)
>> +{
>> +	return (val & ~0x01) * 1000 / 256;
> 
> Why ~0x01 and not ~0x0f ? The lower 4 bits are supposed to be 0.

I can probably change it: I will reevaluate this.

>> +	tmp108->orig_config = regval;
>> +	config = regval;
>> +
> 
> Nitpick, but a separate 'regval' variable is not really necessary.
> Just make config an u32 and use it directly (this actually makes the code
> more efficient on many architectures, since cpu registers tend to be
> at least 32 bit wide and 16 bit accesses result in extra masking).

OK.

>> +	if (device_property_read_bool(dev, "ti,thermostat-mode-comparator"))
>> +		config &= ~TMP108_CONF_TM;
>> +	else
>> +		config |= TMP108_CONF_TM;
>> +
> As suggested separately, I would suggest to drop this and always select comparator mode.

Yep.

>> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
>> +							 tmp108,
>> +							 &tmp108_chip_info,
>> +							 NULL);
>> +	if (IS_ERR(hwmon_dev)) {
>> +		err = PTR_ERR(hwmon_dev);
>> +		dev_err(dev, "unable to register hwmon device: %d", err);
>> +		return err;
>> +	}
> 
> Overall I prefer a simeple
> 	return PTR_ERR_OR_ZERO(hwmon_dev);

Ack.


>> +static int __maybe_unused tmp108_resume(struct device *dev)
>> +{
>> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
>> +	int err;
>> +
>> +	err = regmap_write(tmp108->regmap, TMP108_REG_CONF,
>> +			   tmp108->curr_config);
>> +
>> +	tmp108->ready_time = jiffies;
>> +	if (tmp108->curr_config & TMP108_MODE_CONTINUOUS)
> 
> Since only continuous mode is supported, and it is somewhat unlikely
> that we'll ever support one-shot mode, I think it would be better to
> unconditionally set continuous mode and the delay here and drop
> curr_config entirely. curr_config adds quite some complexity to the
> driver with no real gain.

OK. Due to my ignorance I was assuming that the could would need to restore the current configuration during resume, and also the previous versions (that you did not see) of this code was not using regmap. In fact I see that there is also a function called ‘regmap_sync’ which is used (mainly by audio codecs) to do this (i.e.; as part of device reset but there are examples in resume()). The configuration register is now marked volatile so it would be skipped by regmap_sync anyway.

Should we be concerned about restoring the configuration here?

Thanks for your advice,

John.

Re: [PATCH 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[Guenter Roeck]

Hi John,

On Thu, Dec 01, 2016 at 01:50:22PM -0800, John Muir wrote:
> Hi Guenter,
> 
[ ... ]
> 
> >> +static int __maybe_unused tmp108_resume(struct device *dev)
> >> +{
> >> +	struct tmp108 *tmp108 = dev_get_drvdata(dev);
> >> +	int err;
> >> +
> >> +	err = regmap_write(tmp108->regmap, TMP108_REG_CONF,
> >> +			   tmp108->curr_config);
> >> +
> >> +	tmp108->ready_time = jiffies;
> >> +	if (tmp108->curr_config & TMP108_MODE_CONTINUOUS)
> > 
> > Since only continuous mode is supported, and it is somewhat unlikely
> > that we'll ever support one-shot mode, I think it would be better to
> > unconditionally set continuous mode and the delay here and drop
> > curr_config entirely. curr_config adds quite some complexity to the
> > driver with no real gain.
> 
> OK. Due to my ignorance I was assuming that the could would need to restore the current configuration during resume, and also the previous versions (that you did not see) of this code was not using regmap. In fact I see that there is also a function called ‘regmap_sync’ which is used (mainly by audio codecs) to do this (i.e.; as part of device reset but there are examples in resume()). The configuration register is now marked volatile so it would be skipped by regmap_sync anyway.
> 
> Should we be concerned about restoring the configuration here?
> 
Interesting question. If the chip was really powered off, you would
have to restore the entire configuration, not just the configuration
register. Given that, I think it is sufficient to just restore the
operational mode, ie the value changed when entering suspend.

Where did you find regmap_sync() ? It seems to be hiding from me.

Thanks,
Guenter

Re: [PATCH 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[John Muir]

Hi Guenter,

On Dec 1, 2016, at 2:08 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> 
>> 
>> Should we be concerned about restoring the configuration here?
>> 
> Interesting question. If the chip was really powered off, you would
> have to restore the entire configuration, not just the configuration
> register. Given that, I think it is sufficient to just restore the
> operational mode, ie the value changed when entering suspend.
> 
OK. Will do.

> Where did you find regmap_sync() ? It seems to be hiding from me.

Sorry, I meant regcache_sync().

John.

[PATCH 2/2] devicetree: hwmon: Add documentation for TMP108 driver.

[John Muir]

Simple hwmon binding documentation.

Signed-off-by: John Muir <john@jmuir.com>
---
 Documentation/devicetree/bindings/hwmon/tmp108.txt | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt

diff --git a/Documentation/devicetree/bindings/hwmon/tmp108.txt b/Documentation/devicetree/bindings/hwmon/tmp108.txt
new file mode 100644
index 0000000..7ba08c4
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/tmp108.txt
@@ -0,0 +1,24 @@
+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-comparator : (boolean) select the comparator mode for the
+      thermostat rather than the default interrupt-mode.
+
+Example:
+	tmp108@48 {
+		compatible = "ti,tmp108";
+		reg = <0x48>;
+		ti,thermostat-mode-comparator;
+	};
+
+	tmp108@49 {
+		compatible = "ti,tmp108";
+		reg = <0x49>;
+	};
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH 2/2] devicetree: hwmon: Add documentation for TMP108 driver.

[Guenter Roeck]

Hi John,

On Wed, Nov 30, 2016 at 12:36:19PM -0800, John Muir wrote:
> Simple hwmon binding documentation.
> 
> Signed-off-by: John Muir <john@jmuir.com>
> ---
>  Documentation/devicetree/bindings/hwmon/tmp108.txt | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/tmp108.txt b/Documentation/devicetree/bindings/hwmon/tmp108.txt
> new file mode 100644
> index 0000000..7ba08c4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/tmp108.txt
> @@ -0,0 +1,24 @@
> +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-comparator : (boolean) select the comparator mode for the
> +      thermostat rather than the default interrupt-mode.
> +
I keep arguing with myself over this. Ultimately, I think it is not needed,
for a simple reason: As currently written, using the driver in anything but
comparator mode does not really make sense (because the alert status bits
will be reset after reading them in interrupt mode). Second, interrupt mode
can be determined automatically, based on the presence of SMBus alert support.
Given that, I wonder if it would make more sense to drop this property and
always put the chip into comparator mode for the time being. At a later time,
if and when alert support is added, we can discuss the best approach to
determine how it should be enabled (ie how do we know that the SMBus adapter
supports handling alerts, or would we assume that it always does ?).

What do you think ?

Thanks,
Guenter

> +Example:
> +	tmp108@48 {
> +		compatible = "ti,tmp108";
> +		reg = <0x48>;
> +		ti,thermostat-mode-comparator;
> +	};
> +
> +	tmp108@49 {
> +		compatible = "ti,tmp108";
> +		reg = <0x49>;
> +	};
> -- 
> 2.8.0.rc3.226.g39d4020
> 

Re: [PATCH 2/2] devicetree: hwmon: Add documentation for TMP108 driver.

[John Muir]

Hi Guenter,

On Nov 30, 2016, at 4:42 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> 
>> +Optional node properties:
>> +- ti,thermostat-mode-comparator : (boolean) select the comparator mode for the
>> +      thermostat rather than the default interrupt-mode.
>> +
> I keep arguing with myself over this. Ultimately, I think it is not needed,
> for a simple reason: As currently written, using the driver in anything but
> comparator mode does not really make sense (because the alert status bits
> will be reset after reading them in interrupt mode). Second, interrupt mode
> can be determined automatically, based on the presence of SMBus alert support.
> Given that, I wonder if it would make more sense to drop this property and
> always put the chip into comparator mode for the time being. At a later time,
> if and when alert support is added, we can discuss the best approach to
> determine how it should be enabled (ie how do we know that the SMBus adapter
> supports handling alerts, or would we assume that it always does ?).
> 
> What do you think ?

I did find myself putting the device into comparator mode in order to test the FL and FH bits, so I agree that it can be the default for now. When I can test the Alert pin, we can discuss adding interrupt and SMBus alert support.

Once you have finished reviewing the other patch, I will make that change and re-send.

Thanks,

John.

[PATCH v3 0/2] Texas Instruments TMP108 temperature sensor driver.

[John Muir]

This adds a device driver for the Texas Instruments TMP108 temperature
sensor. The driver provides support to read the temperature, read or modify
the update interval, min and max temperature and hysteresis values, as well
as read current alarm status. Support for alarm interrupts will come in a
future patch.

John Muir (2):
  hwmon: Add Texas Instruments TMP108 temperature sensor driver.
  devicetree: hwmon: Add documentation for TMP108 driver.

 Documentation/devicetree/bindings/hwmon/tmp108.txt |  14 +
 Documentation/hwmon/tmp108                         |  36 ++
 drivers/hwmon/Kconfig                              |  11 +
 drivers/hwmon/Makefile                             |   1 +
 drivers/hwmon/tmp108.c                             | 466 +++++++++++++++++++++
 5 files changed, 528 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
 create mode 100644 Documentation/hwmon/tmp108
 create mode 100644 drivers/hwmon/tmp108.c

-- 
2.8.0.rc3.226.g39d4020

[PATCH v3 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[John Muir]

Add support for the TI TMP108 temperature sensor with some device
configuration parameters.

Signed-off-by: John Muir <john@jmuir.com>
---
 Documentation/hwmon/tmp108 |  36 ++++
 drivers/hwmon/Kconfig      |  11 ++
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/tmp108.c     | 466 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 514 insertions(+)
 create mode 100644 Documentation/hwmon/tmp108
 create mode 100644 drivers/hwmon/tmp108.c

diff --git a/Documentation/hwmon/tmp108 b/Documentation/hwmon/tmp108
new file mode 100644
index 0000000..25802df
--- /dev/null
+++ b/Documentation/hwmon/tmp108
@@ -0,0 +1,36 @@
+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. (This driver does not support interrupts for the alert pin,
+and the device runs in comparator mode.)
+
+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).
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..895ae82
--- /dev/null
+++ b/drivers/hwmon/tmp108.c
@@ -0,0 +1,466 @@
+/* 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/device.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#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_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 */
+					/* When M1 is set, M0 is ignored. */
+
+#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;
+	u16 orig_config;
+	unsigned long ready_time;
+};
+
+/* convert 12-bit TMP108 register value to milliCelsius */
+static inline int tmp108_temp_reg_to_mC(s16 val)
+{
+	return (val & ~0x0f) * 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(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *temp)
+{
+	struct tmp108 *tmp108 = dev_get_drvdata(dev);
+	unsigned int regval;
+	int err, hyst;
+
+	if (type == hwmon_chip) {
+		if (attr == hwmon_chip_update_interval) {
+			err = regmap_read(tmp108->regmap, TMP108_REG_CONF,
+					  &regval);
+			if (err < 0)
+				return err;
+			switch (regval & TMP108_CONF_CONVRATE_MASK) {
+			case TMP108_CONVRATE_0P25HZ:
+			default:
+				*temp = 4000;
+				break;
+			case TMP108_CONVRATE_1HZ:
+				*temp = 1000;
+				break;
+			case TMP108_CONVRATE_4HZ:
+				*temp = 250;
+				break;
+			case TMP108_CONVRATE_16HZ:
+				*temp = 63;
+				break;
+			}
+			return 0;
+		}
+		return -EOPNOTSUPP;
+	}
+
+	switch (attr) {
+	case hwmon_temp_input:
+		/* 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;
+		}
+		err = regmap_read(tmp108->regmap, TMP108_REG_TEMP, &regval);
+		if (err < 0)
+			return err;
+		*temp = tmp108_temp_reg_to_mC(regval);
+		break;
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+		err = regmap_read(tmp108->regmap, attr == hwmon_temp_min ?
+				  TMP108_REG_TLOW : TMP108_REG_THIGH, &regval);
+		if (err < 0)
+			return err;
+		*temp = tmp108_temp_reg_to_mC(regval);
+		break;
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+		err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
+		if (err < 0)
+			return err;
+		*temp = !!(regval & (attr == hwmon_temp_min_alarm ?
+				     TMP108_CONF_FL : TMP108_CONF_FH));
+		break;
+	case hwmon_temp_min_hyst:
+	case hwmon_temp_max_hyst:
+		err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &regval);
+		if (err < 0)
+			return err;
+		switch (regval & TMP108_CONF_HYSTERESIS_MASK) {
+		case TMP108_HYSTERESIS_0C:
+		default:
+			hyst = 0;
+			break;
+		case TMP108_HYSTERESIS_1C:
+			hyst = 1000;
+			break;
+		case TMP108_HYSTERESIS_2C:
+			hyst = 2000;
+			break;
+		case TMP108_HYSTERESIS_4C:
+			hyst = 4000;
+			break;
+		}
+		err = regmap_read(tmp108->regmap, attr == hwmon_temp_min_hyst ?
+				  TMP108_REG_TLOW : TMP108_REG_THIGH, &regval);
+		if (err < 0)
+			return err;
+		*temp = tmp108_temp_reg_to_mC(regval);
+		if (attr == hwmon_temp_min_hyst)
+			*temp += hyst;
+		else
+			*temp -= hyst;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int tmp108_write(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long temp)
+{
+	struct tmp108 *tmp108 = dev_get_drvdata(dev);
+	u32 regval, mask;
+	int err;
+
+	if (type == hwmon_chip) {
+		if (attr == hwmon_chip_update_interval) {
+			if (temp < 156)
+				mask = TMP108_CONVRATE_16HZ;
+			else if (temp < 625)
+				mask = TMP108_CONVRATE_4HZ;
+			else if (temp < 2500)
+				mask = TMP108_CONVRATE_1HZ;
+			else
+				mask = TMP108_CONVRATE_0P25HZ;
+			return regmap_update_bits(tmp108->regmap,
+						  TMP108_REG_CONF,
+						  TMP108_CONF_CONVRATE_MASK,
+						  mask);
+		}
+		return -EOPNOTSUPP;
+	}
+
+	switch (attr) {
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+		temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
+		return regmap_write(tmp108->regmap,
+				    attr == hwmon_temp_min ?
+					TMP108_REG_TLOW : TMP108_REG_THIGH,
+				    tmp108_mC_to_temp_reg(temp));
+	case hwmon_temp_min_hyst:
+	case hwmon_temp_max_hyst:
+		temp = clamp_val(temp, TMP108_TEMP_MIN_MC, TMP108_TEMP_MAX_MC);
+		err = regmap_read(tmp108->regmap,
+				  attr == hwmon_temp_min_hyst ?
+					TMP108_REG_TLOW : TMP108_REG_THIGH,
+				  &regval);
+		if (err < 0)
+			return err;
+		if (attr == hwmon_temp_min_hyst)
+			temp -= tmp108_temp_reg_to_mC(regval);
+		else
+			temp = tmp108_temp_reg_to_mC(regval) - temp;
+		if (temp < 500)
+			mask = TMP108_HYSTERESIS_0C;
+		else if (temp < 1500)
+			mask = TMP108_HYSTERESIS_1C;
+		else if (temp < 3000)
+			mask = TMP108_HYSTERESIS_2C;
+		else
+			mask = TMP108_HYSTERESIS_4C;
+		return regmap_update_bits(tmp108->regmap, TMP108_REG_CONF,
+					  TMP108_CONF_HYSTERESIS_MASK, mask);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t tmp108_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	if (type == hwmon_chip && attr == hwmon_chip_update_interval)
+		return 0644;
+
+	if (type != hwmon_temp)
+		return 0;
+
+	switch (attr) {
+	case hwmon_temp_input:
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+		return 0444;
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+	case hwmon_temp_min_hyst:
+	case hwmon_temp_max_hyst:
+		return 0644;
+	default:
+		return 0;
+	}
+}
+
+static u32 tmp108_chip_config[] = {
+	HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL,
+	0
+};
+
+static const struct hwmon_channel_info tmp108_chip = {
+	.type = hwmon_chip,
+	.config = tmp108_chip_config,
+};
+
+static u32 tmp108_temp_config[] = {
+	HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MIN | HWMON_T_MIN_HYST
+		| HWMON_T_MAX_HYST | HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
+	0
+};
+
+static const struct hwmon_channel_info tmp108_temp = {
+	.type = hwmon_temp,
+	.config = tmp108_temp_config,
+};
+
+static const struct hwmon_channel_info *tmp108_info[] = {
+	&tmp108_chip,
+	&tmp108_temp,
+	NULL
+};
+
+static const struct hwmon_ops tmp108_hwmon_ops = {
+	.is_visible = tmp108_is_visible,
+	.read = tmp108_read,
+	.write = tmp108_write,
+};
+
+static const struct hwmon_chip_info tmp108_chip_info = {
+	.ops = &tmp108_hwmon_ops,
+	.info = tmp108_info,
+};
+
+static void tmp108_restore_config(void *data)
+{
+	struct tmp108 *tmp108 = data;
+
+	regmap_write(tmp108->regmap, TMP108_REG_CONF, tmp108->orig_config);
+}
+
+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)
+{
+	/* Configuration register must be volatile to enable FL and FH. */
+	return reg == TMP108_REG_TEMP || reg == TMP108_REG_CONF;
+}
+
+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;
+	int err;
+	u32 config;
+
+	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;
+
+	dev_set_drvdata(dev, tmp108);
+
+	tmp108->regmap = devm_regmap_init_i2c(client, &tmp108_regmap_config);
+	if (IS_ERR(tmp108->regmap)) {
+		err = PTR_ERR(tmp108->regmap);
+		dev_err(dev, "regmap init failed: %d", err);
+		return err;
+	}
+
+	err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &config);
+	if (err < 0) {
+		dev_err(dev, "error reading config register: %d", err);
+		return err;
+	}
+	tmp108->orig_config = config;
+
+	/* Only continuous mode is supported. */
+	config &= ~TMP108_CONF_MODE_MASK;
+	config |= TMP108_MODE_CONTINUOUS;
+
+	/* Only comparator mode is supported. */
+	config &= ~TMP108_CONF_TM;
+
+	err = regmap_write(tmp108->regmap, TMP108_REG_CONF, config);
+	if (err < 0) {
+		dev_err(dev, "error writing config register: %d", err);
+		return err;
+	}
+
+	tmp108->ready_time = jiffies;
+	if ((tmp108->orig_config & TMP108_CONF_MODE_MASK) ==
+	    TMP108_MODE_SHUTDOWN)
+		tmp108->ready_time +=
+			msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
+
+	err = devm_add_action_or_reset(dev, tmp108_restore_config, tmp108);
+	if (err) {
+		dev_err(dev, "add action or reset failed: %d", err);
+		return err;
+	}
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 tmp108,
+							 &tmp108_chip_info,
+							 NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static int __maybe_unused tmp108_suspend(struct device *dev)
+{
+	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 __maybe_unused tmp108_resume(struct device *dev)
+{
+	struct tmp108 *tmp108 = dev_get_drvdata(dev);
+	int err;
+
+	err = regmap_update_bits(tmp108->regmap, TMP108_REG_CONF,
+				 TMP108_CONF_MODE_MASK, TMP108_MODE_CONTINUOUS);
+	tmp108->ready_time = jiffies +
+			     msecs_to_jiffies(TMP108_CONVERSION_TIME_MS);
+	return err;
+}
+
+static SIMPLE_DEV_PM_OPS(tmp108_dev_pm_ops, tmp108_suspend, tmp108_resume);
+
+static const struct i2c_device_id tmp108_i2c_ids[] = {
+	{ "tmp108", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tmp108_i2c_ids);
+
+#ifdef CONFIG_OF
+static const struct of_device_id tmp108_of_ids[] = {
+	{ .compatible = "ti,tmp108", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, tmp108_of_ids);
+#endif
+
+static struct i2c_driver tmp108_driver = {
+	.driver.name	= DRIVER_NAME,
+	.driver.pm	= &tmp108_dev_pm_ops,
+	.probe		= tmp108_probe,
+	.id_table	= tmp108_i2c_ids,
+};
+
+module_i2c_driver(tmp108_driver);
+
+MODULE_AUTHOR("John Muir <john@jmuir.com>");
+MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH v3 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[Guenter Roeck]

On 12/01/2016 06:32 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>

Nice job. Applied to -next, with a small fixup - see below.

Thanks!
Guenter

> ---

[ ... ]

> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id tmp108_of_ids[] = {
> +	{ .compatible = "ti,tmp108", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, tmp108_of_ids);
> +#endif
> +
> +static struct i2c_driver tmp108_driver = {
> +	.driver.name	= DRIVER_NAME,
> +	.driver.pm	= &tmp108_dev_pm_ops,

Made this
	.driver = {
		.name	= DRIVER_NAME,
		.pm	= &tmp108_dev_pm_ops,
		.of_match_table = of_match_ptr(tmp108_of_ids),
	},

> +	.probe		= tmp108_probe,
> +	.id_table	= tmp108_i2c_ids,
> +};
> +
> +module_i2c_driver(tmp108_driver);
> +
> +MODULE_AUTHOR("John Muir <john@jmuir.com>");
> +MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
> +MODULE_LICENSE("GPL");
>

Re: [PATCH v3 1/2] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

[John Muir]

Hi Gunter,

> On 2016.12.01, at 20:40 , Guenter Roeck <linux@roeck-us.net> wrote:
> 
> On 12/01/2016 06:32 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>
> 
> Nice job. Applied to -next, with a small fixup - see below.

Thank you for your help! I’ll be in touch when I can test the alert.

John.

[PATCH v3 2/2] devicetree: hwmon: Add documentation for TMP108 driver.

[John Muir]

Simple hwmon binding documentation.

Signed-off-by: John Muir <john@jmuir.com>
---
 Documentation/devicetree/bindings/hwmon/tmp108.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt

diff --git a/Documentation/devicetree/bindings/hwmon/tmp108.txt b/Documentation/devicetree/bindings/hwmon/tmp108.txt
new file mode 100644
index 0000000..8c4b10d
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/tmp108.txt
@@ -0,0 +1,14 @@
+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.
+
+Example:
+	tmp108@48 {
+		compatible = "ti,tmp108";
+		reg = <0x48>;
+	};
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH v3 2/2] devicetree: hwmon: Add documentation for TMP108 driver.

[Guenter Roeck]

On 12/01/2016 06:32 PM, John Muir wrote:
> Simple hwmon binding documentation.
>
> Signed-off-by: John Muir <john@jmuir.com>

Straightforward, so I'll apply it w/o waiting for confirmation from the DT maintainers
(Rob - please scream if that is unacceptable).

Thanks,
Guenter

> ---
>  Documentation/devicetree/bindings/hwmon/tmp108.txt | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/tmp108.txt
>
> diff --git a/Documentation/devicetree/bindings/hwmon/tmp108.txt b/Documentation/devicetree/bindings/hwmon/tmp108.txt
> new file mode 100644
> index 0000000..8c4b10d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/tmp108.txt
> @@ -0,0 +1,14 @@
> +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.
> +
> +Example:
> +	tmp108@48 {
> +		compatible = "ti,tmp108";
> +		reg = <0x48>;
> +	};
>