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authorMaciej S. Szmigiero <mail@maciej.szmigiero.name>2015-06-21 16:54:44 +0300
committerGuenter Roeck <linux@roeck-us.net>2015-06-22 08:54:53 +0300
commit761c1770f2bf36a323ab97e2e1780db4f9b8a6fe (patch)
tree5fdfb189a1d4980916069a418015573ab736957b /drivers/hwmon/tc74.c
parentf6725ae2f1ae266589ab177461e308bb2f86f9ee (diff)
downloadlinux-761c1770f2bf36a323ab97e2e1780db4f9b8a6fe.tar.xz
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>
Diffstat (limited to 'drivers/hwmon/tc74.c')
-rw-r--r--drivers/hwmon/tc74.c177
1 files changed, 177 insertions, 0 deletions
diff --git a/drivers/hwmon/tc74.c b/drivers/hwmon/tc74.c
new file mode 100644
index 000000000000..d95165158800
--- /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");