/* * mcp3021.c - driver for Microchip MCP3021 and MCP3221 * * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc. * Author: Mingkai Hu <Mingkai.hu@freescale.com> * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de> * * 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 MCP3221_SAR_SHIFT 0 #define MCP3221_SAR_MASK 0xfff #define MCP3221_OUTPUT_RES 12 /* 12-bit resolution */ enum chips { mcp3021, mcp3221 }; /* * Client data (each client gets its own) */ struct mcp3021_data { struct device *hwmon_dev; u32 vdd; /* device power supply */ u16 sar_shift; u16 sar_mask; u8 output_res; }; static int mcp3021_read16(struct i2c_client *client) { struct mcp3021_data *data = i2c_get_clientdata(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 >> data->sar_shift) & data->sar_mask; return reg; } static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val) { return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res); } 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, 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 = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data), GFP_KERNEL); if (!data) return -ENOMEM; i2c_set_clientdata(client, data); switch (id->driver_data) { case mcp3021: data->sar_shift = MCP3021_SAR_SHIFT; data->sar_mask = MCP3021_SAR_MASK; data->output_res = MCP3021_OUTPUT_RES; break; case mcp3221: data->sar_shift = MCP3221_SAR_SHIFT; data->sar_mask = MCP3221_SAR_MASK; data->output_res = MCP3221_OUTPUT_RES; break; } if (dev_get_platdata(&client->dev)) { data->vdd = *(u32 *)dev_get_platdata(&client->dev); if (data->vdd > MCP3021_VDD_MAX || data->vdd < MCP3021_VDD_MIN) return -EINVAL; } else { data->vdd = MCP3021_VDD_REF; } err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr); if (err) return err; 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); 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); return 0; } static const struct i2c_device_id mcp3021_id[] = { { "mcp3021", mcp3021 }, { "mcp3221", mcp3221 }, { } }; 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/MCP3221 driver"); MODULE_LICENSE("GPL");