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authorIngo Molnar <mingo@kernel.org>2012-04-14 13:18:27 +0200
committerIngo Molnar <mingo@kernel.org>2012-04-14 13:19:04 +0200
commit6ac1ef482d7ae0c690f1640bf6eb818ff9a2d91e (patch)
tree021cc9f6b477146fcebe6f3be4752abfa2ba18a9 /drivers/hwmon/mcp3021.c
parent682968e0c425c60f0dde37977e5beb2b12ddc4cc (diff)
parenta385ec4f11bdcf81af094c03e2444ee9b7fad2e5 (diff)
Merge branch 'perf/core' into perf/uprobes
Merge in latest upstream (and the latest perf development tree), to prepare for tooling changes, and also to pick up v3.4 MM changes that the uprobes code needs to take care of. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/hwmon/mcp3021.c')
-rw-r--r--drivers/hwmon/mcp3021.c171
1 files changed, 171 insertions, 0 deletions
diff --git a/drivers/hwmon/mcp3021.c b/drivers/hwmon/mcp3021.c
new file mode 100644
index 00000000000..d0afc0cd3ff
--- /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");