sensor: Add driver for MCP9808 temperature sensor

The driver only supports simple temperature readings.  It does not
support the alarm feature.  Datasheet available at
<http://ww1.microchip.com/downloads/en/DeviceDoc/25095A.pdf>.

Origin: Original
Change-Id: I283e6697fc6947975323d280f5ff0ba625fac5a9
Signed-off-by: Vlad Dogaru <vlad.dogaru@intel.com>

drivers/sensor/Kconfig

@@ -43,3 +43,38 @@ config SENSOR_DEBUG
 	depends on SENSOR && PRINTK
 	help
 	  This option enables debug output for sensor drivers.
+
+menuconfig MCP9808
+	bool "MCP9808 temperature sensor"
+	depends on SENSOR && I2C
+	default n
+	help
+	 Enable driver for MCP9808 temperature sensor.
+
+config MCP9808_DEV_NAME
+	string "MCP9808 device name"
+	depends on MCP9808
+	default "MCP9808"
+
+config MCP9808_INIT_PRIORITY
+	int
+	depends on MCP9808
+	default 70
+	prompt "Init priority"
+	help
+	 Device driver initialization priority.
+
+config MCP9808_I2C_ADDR
+	hex "MCP9808 I2C slave address"
+	depends on MCP9808
+	default 0x18
+	help
+	 Specify the I2C slave address for the MCP9808.
+
+config MCP9808_I2C_DEV_NAME
+	string "I2C master where MCP9808 is connected"
+	depends on MCP9808
+	default "I2C0"
+	help
+	 Specify the device name of the I2C master device to which MCP9808 is
+	 connected.

drivers/sensor/Makefile

@@ -1,3 +1,5 @@
 ccflags-y +=-I$(srctree)/drivers
 
 obj-$(CONFIG_SENSOR_DELAYED_WORK) += sensor.o
+
+obj-$(CONFIG_MCP9808) += sensor_mcp9808.o

drivers/sensor/sensor_mcp9808.c

@@ -0,0 +1,119 @@
+/* sensor_mcp9808.c - Driver for MCP9808 temperature sensor */
+
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <nanokernel.h>
+#include <i2c.h>
+#include <sensor.h>
+#include <init.h>
+#include <gpio.h>
+#include <misc/byteorder.h>
+#include "sensor_mcp9808.h"
+
+#ifndef CONFIG_SENSOR_DEBUG
+#define DBG(...) { ; }
+#else
+#include <misc/printk.h>
+#define DBG printk
+#endif /* CONFIG_SENSOR_DEBUG */
+
+static int mcp9808_reg_read(struct mcp9808_data *data, uint8_t reg, uint16_t *val)
+{
+	int ret;
+
+	struct i2c_msg msgs[2] = {
+		{
+			.buf = &reg,
+			.len = 1,
+			.flags = I2C_MSG_WRITE | I2C_MSG_RESTART,
+		},
+		{
+			.buf = (uint8_t *)val,
+			.len = 2,
+			.flags = I2C_MSG_READ | I2C_MSG_STOP,
+		},
+	};
+
+	ret = i2c_transfer(data->i2c_master, msgs, 2, data->i2c_slave_addr);
+	if (ret) {
+		return ret;
+	}
+
+	*val = sys_be16_to_cpu(*val);
+
+	return DEV_OK;
+}
+
+static int mcp9808_sample_fetch(struct device *dev)
+{
+	struct mcp9808_data *data = dev->driver_data;
+
+	return mcp9808_reg_read(data, MCP9808_REG_TEMP_AMB, &data->reg_val);
+}
+
+static int mcp9808_channel_get(struct device *dev,
+			       enum sensor_channel chan,
+			       struct sensor_value *val)
+{
+	struct mcp9808_data *data = dev->driver_data;
+
+#ifdef CONFIG_SENSOR_DEBUG
+	if (chan != SENSOR_CHAN_TEMP) {
+		return DEV_INVALID_OP;
+	}
+#endif
+
+	val->type = SENSOR_TYPE_INT_PLUS_MICRO;
+
+	val->val1 = (data->reg_val & MCP9808_TEMP_INT_MASK) >>
+		     MCP9808_TEMP_INT_SHIFT;
+	val->val2 = (data->reg_val & MCP9808_TEMP_FRAC_MASK) * 62500;
+
+	if (data->reg_val & MCP9808_SIGN_BIT) {
+		val->val1 -= 256;
+	}
+
+	return DEV_OK;
+}
+
+static struct sensor_driver_api mcp9808_api_funcs = {
+	.sample_fetch = mcp9808_sample_fetch,
+	.channel_get = mcp9808_channel_get,
+};
+
+int mcp9808_init(struct device *dev)
+{
+	struct mcp9808_data *data = dev->driver_data;
+
+	dev->driver_api = &mcp9808_api_funcs;
+
+	data->i2c_master = device_get_binding(CONFIG_MCP9808_I2C_DEV_NAME);
+	if (!data->i2c_master) {
+		DBG("mcp9808: i2c master not found: %s\n",
+		    CONFIG_MCP9808_I2C_DEV_NAME);
+		return DEV_INVALID_CONF;
+	}
+
+	data->i2c_slave_addr = CONFIG_MCP9808_I2C_ADDR;
+
+	return DEV_OK;
+}
+
+static struct mcp9808_data mcp9808_data;
+
+DEVICE_INIT(mcp9808, CONFIG_MCP9808_DEV_NAME, mcp9808_init, &mcp9808_data,
+	    NULL, SECONDARY, CONFIG_MCP9808_INIT_PRIORITY);

drivers/sensor/sensor_mcp9808.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __SENSOR_MCP9808_H__
+#define __SENSOR_MCP9808_H__
+
+#include <stdint.h>
+#include <device.h>
+#include <misc/util.h>
+
+#define MCP9808_REG_TEMP_AMB		0x05
+
+#define MCP9808_SIGN_BIT		BIT(12)
+#define MCP9808_TEMP_INT_MASK		0x0ff0
+#define MCP9808_TEMP_INT_SHIFT		4
+#define MCP9808_TEMP_FRAC_MASK		0x000f
+
+struct mcp9808_data {
+	struct device *i2c_master;
+	uint16_t i2c_slave_addr;
+
+	uint16_t reg_val;
+};
+
+#endif /* __SENSOR_MCP9808_H__ */