Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / hwmon / htu21.c

diff --git a/kernel/drivers/hwmon/htu21.c b/kernel/drivers/hwmon/htu21.c
new file mode 100644 (file)
index 0000000..4c3bbb7
--- /dev/null
+++ b/kernel/drivers/hwmon/htu21.c
@@ -0,0 +1,174 @@
+/*
+ * Measurement Specialties HTU21D humidity and temperature sensor driver
+ *
+ * Copyright (C) 2013 William Markezana <william.markezana@meas-spec.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/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>
+
+/* HTU21 Commands */
+#define HTU21_T_MEASUREMENT_HM 0xE3
+#define HTU21_RH_MEASUREMENT_HM        0xE5
+
+struct htu21 {
+       struct i2c_client *client;
+       struct mutex lock;
+       bool valid;
+       unsigned long last_update;
+       int temperature;
+       int humidity;
+};
+
+static inline int htu21_temp_ticks_to_millicelsius(int ticks)
+{
+       ticks &= ~0x0003; /* clear status bits */
+       /*
+        * Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
+        * optimized for integer fixed point (3 digits) arithmetic
+        */
+       return ((21965 * ticks) >> 13) - 46850;
+}
+
+static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
+{
+       ticks &= ~0x0003; /* clear status bits */
+       /*
+        * Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
+        * optimized for integer fixed point (3 digits) arithmetic
+        */
+       return ((15625 * ticks) >> 13) - 6000;
+}
+
+static int htu21_update_measurements(struct device *dev)
+{
+       struct htu21 *htu21 = dev_get_drvdata(dev);
+       struct i2c_client *client = htu21->client;
+       int ret = 0;
+
+       mutex_lock(&htu21->lock);
+
+       if (time_after(jiffies, htu21->last_update + HZ / 2) ||
+           !htu21->valid) {
+               ret = i2c_smbus_read_word_swapped(client,
+                                                 HTU21_T_MEASUREMENT_HM);
+               if (ret < 0)
+                       goto out;
+               htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
+               ret = i2c_smbus_read_word_swapped(client,
+                                                 HTU21_RH_MEASUREMENT_HM);
+               if (ret < 0)
+                       goto out;
+               htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
+               htu21->last_update = jiffies;
+               htu21->valid = true;
+       }
+out:
+       mutex_unlock(&htu21->lock);
+
+       return ret >= 0 ? 0 : ret;
+}
+
+static ssize_t htu21_show_temperature(struct device *dev,
+                                     struct device_attribute *attr, char *buf)
+{
+       struct htu21 *htu21 = dev_get_drvdata(dev);
+       int ret;
+
+       ret = htu21_update_measurements(dev);
+       if (ret < 0)
+               return ret;
+       return sprintf(buf, "%d\n", htu21->temperature);
+}
+
+static ssize_t htu21_show_humidity(struct device *dev,
+                                  struct device_attribute *attr, char *buf)
+{
+       struct htu21 *htu21 = dev_get_drvdata(dev);
+       int ret;
+
+       ret = htu21_update_measurements(dev);
+       if (ret < 0)
+               return ret;
+       return sprintf(buf, "%d\n", htu21->humidity);
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
+                         htu21_show_temperature, NULL, 0);
+static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
+                         htu21_show_humidity, NULL, 0);
+
+static struct attribute *htu21_attrs[] = {
+       &sensor_dev_attr_temp1_input.dev_attr.attr,
+       &sensor_dev_attr_humidity1_input.dev_attr.attr,
+       NULL
+};
+
+ATTRIBUTE_GROUPS(htu21);
+
+static int htu21_probe(struct i2c_client *client,
+                      const struct i2c_device_id *id)
+{
+       struct device *dev = &client->dev;
+       struct htu21 *htu21;
+       struct device *hwmon_dev;
+
+       if (!i2c_check_functionality(client->adapter,
+                                    I2C_FUNC_SMBUS_READ_WORD_DATA)) {
+               dev_err(&client->dev,
+                       "adapter does not support SMBus word transactions\n");
+               return -ENODEV;
+       }
+
+       htu21 = devm_kzalloc(dev, sizeof(*htu21), GFP_KERNEL);
+       if (!htu21)
+               return -ENOMEM;
+
+       htu21->client = client;
+       mutex_init(&htu21->lock);
+
+       hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
+                                                          htu21,
+                                                          htu21_groups);
+       return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id htu21_id[] = {
+       { "htu21", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, htu21_id);
+
+static struct i2c_driver htu21_driver = {
+       .class = I2C_CLASS_HWMON,
+       .driver = {
+               .name   = "htu21",
+       },
+       .probe       = htu21_probe,
+       .id_table    = htu21_id,
+};
+
+module_i2c_driver(htu21_driver);
+
+MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
+MODULE_DESCRIPTION("MEAS HTU21D humidity and temperature sensor driver");
+MODULE_LICENSE("GPL");