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

Signed-off-by: John Muir <j...@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 <j...@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 <j...@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 <j...@jmuir.com>");
+MODULE_DESCRIPTION("Texas Instruments TMP108 temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.8.0.rc3.226.g39d4020

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