Date:   Sat, 26 Nov 2016 21:15:35 -0800
From:   John Muir <john@...ir.com>
To:     Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org
Cc:     John Muir <john@...ir.com>
Subject: [PATCH 1/3] hwmon: Add Texas Instruments TMP108 temperature sensor driver.

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

Signed-off-by: John Muir <john@...ir.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
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
+      thermostat rather than the default interrupt-mode.
+- ti,alert-active-high : (boolean) make the alert pin active-high instead of
+      the default active-low.
+- 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).
+
+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@...ir.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@...ir.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>
+
+#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;
+
+	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);
+
+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) {
+		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);
+}
+
+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);
+	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);
+
+	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)
+{
+	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@...ir.com>");
+MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.8.0.rc3.226.g39d4020

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