1/*
  2 * mcp3021.c - driver for Microchip MCP3021 and MCP3221
  3 *
  4 * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
  5 * Author: Mingkai Hu <Mingkai.hu@freescale.com>
  6 * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>
  7 *
  8 * This driver export the value of analog input voltage to sysfs, the
  9 * voltage unit is mV. Through the sysfs interface, lm-sensors tool
 10 * can also display the input voltage.
 11 *
 12 * This program is free software; you can redistribute it and/or modify
 13 * it under the terms of the GNU General Public License as published by
 14 * the Free Software Foundation; either version 2 of the License, or
 15 * (at your option) any later version.
 16 */
 17
 18#include <linux/kernel.h>
 19#include <linux/module.h>
 20#include <linux/hwmon.h>
 21#include <linux/slab.h>
 22#include <linux/i2c.h>
 23#include <linux/err.h>
 24#include <linux/device.h>
 25
 26/* Vdd info */
 27#define MCP3021_VDD_MAX		5500
 28#define MCP3021_VDD_MIN		2700
 29#define MCP3021_VDD_REF		3300
 30
 31/* output format */
 32#define MCP3021_SAR_SHIFT	2
 33#define MCP3021_SAR_MASK	0x3ff
 34
 35#define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */
 36#define MCP3021_OUTPUT_SCALE	4
 37
 38#define MCP3221_SAR_SHIFT	0
 39#define MCP3221_SAR_MASK	0xfff
 40#define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */
 41#define MCP3221_OUTPUT_SCALE	1
 42
 43enum chips {
 44	mcp3021,
 45	mcp3221
 46};
 47
 48/*
 49 * Client data (each client gets its own)
 50 */
 51struct mcp3021_data {
 52	struct device *hwmon_dev;
 53	u32 vdd;	/* device power supply */
 54	u16 sar_shift;
 55	u16 sar_mask;
 56	u8 output_res;
 57	u8 output_scale;
 58};
 59
 60static int mcp3021_read16(struct i2c_client *client)
 61{
 62	struct mcp3021_data *data = i2c_get_clientdata(client);
 63	int ret;
 64	u16 reg;
 65	__be16 buf;
 66
 67	ret = i2c_master_recv(client, (char *)&buf, 2);
 68	if (ret < 0)
 69		return ret;
 70	if (ret != 2)
 71		return -EIO;
 72
 73	/* The output code of the MCP3021 is transmitted with MSB first. */
 74	reg = be16_to_cpu(buf);
 75
 76	/*
 77	 * The ten-bit output code is composed of the lower 4-bit of the
 78	 * first byte and the upper 6-bit of the second byte.
 79	 */
 80	reg = (reg >> data->sar_shift) & data->sar_mask;
 81
 82	return reg;
 83}
 84
 85static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
 86{
 87	if (val == 0)
 88		return 0;
 89
 90	val = val * data->output_scale - data->output_scale / 2;
 91
 92	return val * DIV_ROUND_CLOSEST(data->vdd,
 93			(1 << data->output_res) * data->output_scale);
 94}
 95
 96static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
 97		char *buf)
 98{
 99	struct i2c_client *client = to_i2c_client(dev);
100	struct mcp3021_data *data = i2c_get_clientdata(client);
101	int reg, in_input;
102
103	reg = mcp3021_read16(client);
104	if (reg < 0)
105		return reg;
106
107	in_input = volts_from_reg(data, reg);
108
109	return sprintf(buf, "%d\n", in_input);
110}
111
112static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
113
114static int mcp3021_probe(struct i2c_client *client,
115				const struct i2c_device_id *id)
116{
117	int err;
118	struct mcp3021_data *data = NULL;
119
120	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
121		return -ENODEV;
122
123	data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
124			    GFP_KERNEL);
125	if (!data)
126		return -ENOMEM;
127
128	i2c_set_clientdata(client, data);
129
130	switch (id->driver_data) {
131	case mcp3021:
132		data->sar_shift = MCP3021_SAR_SHIFT;
133		data->sar_mask = MCP3021_SAR_MASK;
134		data->output_res = MCP3021_OUTPUT_RES;
135		data->output_scale = MCP3021_OUTPUT_SCALE;
136		break;
137
138	case mcp3221:
139		data->sar_shift = MCP3221_SAR_SHIFT;
140		data->sar_mask = MCP3221_SAR_MASK;
141		data->output_res = MCP3221_OUTPUT_RES;
142		data->output_scale = MCP3221_OUTPUT_SCALE;
143		break;
144	}
145
146	if (dev_get_platdata(&client->dev)) {
147		data->vdd = *(u32 *)dev_get_platdata(&client->dev);
148		if (data->vdd > MCP3021_VDD_MAX || data->vdd < MCP3021_VDD_MIN)
149			return -EINVAL;
150	} else {
151		data->vdd = MCP3021_VDD_REF;
152	}
153
154	err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
155	if (err)
156		return err;
157
158	data->hwmon_dev = hwmon_device_register(&client->dev);
159	if (IS_ERR(data->hwmon_dev)) {
160		err = PTR_ERR(data->hwmon_dev);
161		goto exit_remove;
162	}
163
164	return 0;
165
166exit_remove:
167	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
168	return err;
169}
170
171static int mcp3021_remove(struct i2c_client *client)
172{
173	struct mcp3021_data *data = i2c_get_clientdata(client);
174
175	hwmon_device_unregister(data->hwmon_dev);
176	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
177
178	return 0;
179}
180
181static const struct i2c_device_id mcp3021_id[] = {
182	{ "mcp3021", mcp3021 },
183	{ "mcp3221", mcp3221 },
184	{ }
185};
186MODULE_DEVICE_TABLE(i2c, mcp3021_id);
187
188static struct i2c_driver mcp3021_driver = {
189	.driver = {
190		.name = "mcp3021",
191	},
192	.probe = mcp3021_probe,
193	.remove = mcp3021_remove,
194	.id_table = mcp3021_id,
195};
196
197module_i2c_driver(mcp3021_driver);
198
199MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
200MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
201MODULE_LICENSE("GPL");