hwmon: Add MCP3021 ADC driver
Add I2C driver for MCP3021 that is an ADC chip from Microchip.
The MCP3021 is a successive approximation A/D converter (ADC)
with 10-bit resolution.
The driver export the value of Vin to sysfs, the voltage unit is
mV. Through the sysfs interface, lm-sensors tool can also display
Vin voltage.
Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com>
Signed-off-by: Xie Xiaobo <X.Xie@freescale.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/hwmon/mcp3021.c b/drivers/hwmon/mcp3021.c
new file mode 100644
index 0000000..d0afc0c
--- /dev/null
+++ b/drivers/hwmon/mcp3021.c
@@ -0,0 +1,171 @@
+/*
+ * mcp3021.c - driver for the Microchip MCP3021 chip
+ *
+ * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
+ * Author: Mingkai Hu <Mingkai.hu@freescale.com>
+ *
+ * This driver export the value of analog input voltage to sysfs, the
+ * voltage unit is mV. Through the sysfs interface, lm-sensors tool
+ * can also display the input voltage.
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/hwmon.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/device.h>
+
+/* Vdd info */
+#define MCP3021_VDD_MAX 5500
+#define MCP3021_VDD_MIN 2700
+#define MCP3021_VDD_REF 3300
+
+/* output format */
+#define MCP3021_SAR_SHIFT 2
+#define MCP3021_SAR_MASK 0x3ff
+
+#define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */
+#define MCP3021_OUTPUT_SCALE 4
+
+/*
+ * Client data (each client gets its own)
+ */
+struct mcp3021_data {
+ struct device *hwmon_dev;
+ u32 vdd; /* device power supply */
+};
+
+static int mcp3021_read16(struct i2c_client *client)
+{
+ int ret;
+ u16 reg;
+ __be16 buf;
+
+ ret = i2c_master_recv(client, (char *)&buf, 2);
+ if (ret < 0)
+ return ret;
+ if (ret != 2)
+ return -EIO;
+
+ /* The output code of the MCP3021 is transmitted with MSB first. */
+ reg = be16_to_cpu(buf);
+
+ /*
+ * The ten-bit output code is composed of the lower 4-bit of the
+ * first byte and the upper 6-bit of the second byte.
+ */
+ reg = (reg >> MCP3021_SAR_SHIFT) & MCP3021_SAR_MASK;
+
+ return reg;
+}
+
+static inline u16 volts_from_reg(u16 vdd, u16 val)
+{
+ if (val == 0)
+ return 0;
+
+ val = val * MCP3021_OUTPUT_SCALE - MCP3021_OUTPUT_SCALE / 2;
+
+ return val * DIV_ROUND_CLOSEST(vdd,
+ (1 << MCP3021_OUTPUT_RES) * MCP3021_OUTPUT_SCALE);
+}
+
+static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct mcp3021_data *data = i2c_get_clientdata(client);
+ int reg, in_input;
+
+ reg = mcp3021_read16(client);
+ if (reg < 0)
+ return reg;
+
+ in_input = volts_from_reg(data->vdd, reg);
+ return sprintf(buf, "%d\n", in_input);
+}
+
+static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
+
+static int mcp3021_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ int err;
+ struct mcp3021_data *data = NULL;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ data = kzalloc(sizeof(struct mcp3021_data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ i2c_set_clientdata(client, data);
+
+ if (client->dev.platform_data) {
+ data->vdd = *(u32 *)client->dev.platform_data;
+ if (data->vdd > MCP3021_VDD_MAX ||
+ data->vdd < MCP3021_VDD_MIN) {
+ err = -EINVAL;
+ goto exit_free;
+ }
+ } else
+ data->vdd = MCP3021_VDD_REF;
+
+ err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
+ if (err)
+ goto exit_free;
+
+ data->hwmon_dev = hwmon_device_register(&client->dev);
+ if (IS_ERR(data->hwmon_dev)) {
+ err = PTR_ERR(data->hwmon_dev);
+ goto exit_remove;
+ }
+
+ return 0;
+
+exit_remove:
+ sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
+exit_free:
+ kfree(data);
+ return err;
+}
+
+static int mcp3021_remove(struct i2c_client *client)
+{
+ struct mcp3021_data *data = i2c_get_clientdata(client);
+
+ hwmon_device_unregister(data->hwmon_dev);
+ sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
+ kfree(data);
+
+ return 0;
+}
+
+static const struct i2c_device_id mcp3021_id[] = {
+ { "mcp3021", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, mcp3021_id);
+
+static struct i2c_driver mcp3021_driver = {
+ .driver = {
+ .name = "mcp3021",
+ },
+ .probe = mcp3021_probe,
+ .remove = mcp3021_remove,
+ .id_table = mcp3021_id,
+};
+
+module_i2c_driver(mcp3021_driver);
+
+MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
+MODULE_DESCRIPTION("Microchip MCP3021 driver");
+MODULE_LICENSE("GPL");