diff options
Diffstat (limited to 'drivers/hwmon/mcp3021.c')
| -rw-r--r-- | drivers/hwmon/mcp3021.c | 171 |
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"); |