hwmon: add driver for Microchip TC74

Add hwmon driver for the Microchip TC74.

The TC74 is a single-input 8-bit I2C temperature sensor,
with +-2 degrees centigrade accuracy.

Signed-off-by: Maciej Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/Documentation/hwmon/tc74 b/Documentation/hwmon/tc74
new file mode 100644 (file)
index 0000000..43027aa
--- /dev/null
+++ b/Documentation/hwmon/tc74
@@ -0,0 +1,20 @@
+Kernel driver tc74
+====================
+
+Supported chips:
+   * Microchip TC74
+     Prefix: 'tc74'
+     Datasheet: Publicly available at Microchip website.
+
+Description
+-----------
+
+Driver supports the above part.
+
+The tc74 has an 8-bit sensor, with 1 degree centigrade resolution
+and +- 2 degrees centigrade accuracy.
+
+Notes
+-----
+
+Currently entering low power standby mode is not supported.

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 9c9d38b1e92e5866008250f1f045a3531e55b7e9..54075a07d2a1674035f5a80a6fb211331ee1eaa7 100644 (file)
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1452,6 +1452,16 @@ config SENSORS_INA2XX
          This driver can also be built as a module.  If so, the module
          will be called ina2xx.
 
+config SENSORS_TC74
+       tristate "Microchip TC74"
+       depends on I2C
+       help
+         If you say yes here you get support for Microchip TC74 single
+         input temperature sensor chips.
+
+         This driver can also be built as a module.  If so, the module
+         will be called tc74.
+
 config SENSORS_THMC50
        tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
        depends on I2C

diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index b4a40f17e2aa5211f767323f736cab872c16528d..ab904027f074ed0841c27945b6d6c6092fb52708 100644 (file)
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -140,6 +140,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
 obj-$(CONFIG_SENSORS_AMC6821)  += amc6821.o
+obj-$(CONFIG_SENSORS_TC74)     += tc74.o
 obj-$(CONFIG_SENSORS_THMC50)   += thmc50.o
 obj-$(CONFIG_SENSORS_TMP102)   += tmp102.o
 obj-$(CONFIG_SENSORS_TMP103)   += tmp103.o

diff --git a/drivers/hwmon/tc74.c b/drivers/hwmon/tc74.c
new file mode 100644 (file)
index 0000000..d951651
--- /dev/null
+++ b/drivers/hwmon/tc74.c
@@ -0,0 +1,177 @@
+/*
+ * An hwmon driver for the Microchip TC74
+ *
+ * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
+ *
+ * Based on ad7414.c:
+ *     Copyright 2006 Stefan Roese, DENX Software Engineering
+ *     Copyright 2008 Sean MacLennan, PIKA Technologies
+ *     Copyright 2008 Frank Edelhaeuser, Spansion Inc.
+ *
+ * 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.
+ */
+
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+/* TC74 registers */
+#define TC74_REG_TEMP          0x00
+#define TC74_REG_CONFIG                0x01
+
+struct tc74_data {
+       struct i2c_client       *client;
+       struct mutex            lock;   /* atomic read data updates */
+       bool                    valid;  /* validity of fields below */
+       unsigned long           next_update;    /* In jiffies */
+       s8                      temp_input;     /* Temp value in dC */
+};
+
+static int tc74_update_device(struct device *dev)
+{
+       struct tc74_data *data = dev_get_drvdata(dev);
+       struct i2c_client *client = data->client;
+       int ret;
+
+       ret = mutex_lock_interruptible(&data->lock);
+       if (ret)
+               return ret;
+
+       if (time_after(jiffies, data->next_update) || !data->valid) {
+               s32 value;
+
+               value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
+               if (value < 0) {
+                       dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
+                               (int)value);
+
+                       ret = value;
+                       goto ret_unlock;
+               }
+
+               if (!(value & BIT(6))) {
+                       /* not ready yet */
+
+                       ret = -EAGAIN;
+                       goto ret_unlock;
+               }
+
+               value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
+               if (value < 0) {
+                       dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
+                               (int)value);
+
+                       ret = value;
+                       goto ret_unlock;
+               }
+
+               data->temp_input = value;
+               data->next_update = jiffies + HZ / 4;
+               data->valid = true;
+       }
+
+ret_unlock:
+       mutex_unlock(&data->lock);
+
+       return ret;
+}
+
+static ssize_t show_temp_input(struct device *dev,
+                              struct device_attribute *attr, char *buf)
+{
+       struct tc74_data *data = dev_get_drvdata(dev);
+       int ret;
+
+       ret = tc74_update_device(dev);
+       if (ret)
+               return ret;
+
+       return sprintf(buf, "%d\n", data->temp_input * 1000);
+}
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
+
+static struct attribute *tc74_attrs[] = {
+       &sensor_dev_attr_temp1_input.dev_attr.attr,
+       NULL
+};
+
+ATTRIBUTE_GROUPS(tc74);
+
+static int tc74_probe(struct i2c_client *client,
+                     const struct i2c_device_id *dev_id)
+{
+       struct device *dev = &client->dev;
+       struct tc74_data *data;
+       struct device *hwmon_dev;
+       s32 conf;
+
+       if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+               return -EOPNOTSUPP;
+
+       data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       data->client = client;
+       mutex_init(&data->lock);
+
+       /* Make sure the chip is powered up. */
+       conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
+       if (conf < 0) {
+               dev_err(dev, "unable to read config register\n");
+
+               return conf;
+       }
+
+       if (conf & 0x3f) {
+               dev_err(dev, "invalid config register value\n");
+
+               return -ENODEV;
+       }
+
+       if (conf & BIT(7)) {
+               s32 ret;
+
+               conf &= ~BIT(7);
+
+               ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
+               if (ret)
+                       dev_warn(dev, "unable to disable STANDBY\n");
+       }
+
+       hwmon_dev = devm_hwmon_device_register_with_groups(dev,
+                                                          client->name,
+                                                          data, tc74_groups);
+       return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id tc74_id[] = {
+       { "tc74", 0 },
+       {}
+};
+MODULE_DEVICE_TABLE(i2c, tc74_id);
+
+static struct i2c_driver tc74_driver = {
+       .driver = {
+               .name   = "tc74",
+       },
+       .probe  = tc74_probe,
+       .id_table = tc74_id,
+};
+
+module_i2c_driver(tc74_driver);
+
+MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
+
+MODULE_DESCRIPTION("TC74 driver");
+MODULE_LICENSE("GPL");