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#define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */
 35
 36#define MCP3221_SAR_SHIFT	0
 37#define MCP3221_SAR_MASK	0xfff
 38#define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */
 39
 40enum chips {
 41	mcp3021,
 42	mcp3221
 43};
 44
 45/*
 46 * Client data (each client gets its own)
 47 */
 48struct mcp3021_data {
 49	struct device *hwmon_dev;
 50	u32 vdd;	/* device power supply */
 51	u16 sar_shift;
 52	u16 sar_mask;
 53	u8 output_res;
 54};
 55
 56static int mcp3021_read16(struct i2c_client *client)
 57{
 58	struct mcp3021_data *data = i2c_get_clientdata(client);
 59	int ret;
 60	u16 reg;
 61	__be16 buf;
 62
 63	ret = i2c_master_recv(client, (char *)&buf, 2);
 64	if (ret < 0)
 65		return ret;
 66	if (ret != 2)
 67		return -EIO;
 68
 69	/* The output code of the MCP3021 is transmitted with MSB first. */
 70	reg = be16_to_cpu(buf);
 71
 72	/*
 73	 * The ten-bit output code is composed of the lower 4-bit of the
 74	 * first byte and the upper 6-bit of the second byte.
 75	 */
 76	reg = (reg >> data->sar_shift) & data->sar_mask;
 77
 78	return reg;
 79}
 80
 81static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
 82{
 83	return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
 84}
 85
 86static ssize_t show_in_input(struct device *dev, struct device_attribute *attr,
 87		char *buf)
 88{
 89	struct i2c_client *client = to_i2c_client(dev);
 90	struct mcp3021_data *data = i2c_get_clientdata(client);
 91	int reg, in_input;
 92
 93	reg = mcp3021_read16(client);
 94	if (reg < 0)
 95		return reg;
 96
 97	in_input = volts_from_reg(data, reg);
 98
 99	return sprintf(buf, "%d\n", in_input);
100}
101
102static DEVICE_ATTR(in0_input, S_IRUGO, show_in_input, NULL);
103
104static int mcp3021_probe(struct i2c_client *client,
105				const struct i2c_device_id *id)
106{
107	int err;
108	struct mcp3021_data *data = NULL;
109
110	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
111		return -ENODEV;
112
113	data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
114			    GFP_KERNEL);
115	if (!data)
116		return -ENOMEM;
117
118	i2c_set_clientdata(client, data);
119
120	switch (id->driver_data) {
121	case mcp3021:
122		data->sar_shift = MCP3021_SAR_SHIFT;
123		data->sar_mask = MCP3021_SAR_MASK;
124		data->output_res = MCP3021_OUTPUT_RES;
125		break;
126
127	case mcp3221:
128		data->sar_shift = MCP3221_SAR_SHIFT;
129		data->sar_mask = MCP3221_SAR_MASK;
130		data->output_res = MCP3221_OUTPUT_RES;
131		break;
132	}
133
134	if (dev_get_platdata(&client->dev)) {
135		data->vdd = *(u32 *)dev_get_platdata(&client->dev);
136		if (data->vdd > MCP3021_VDD_MAX || data->vdd < MCP3021_VDD_MIN)
137			return -EINVAL;
138	} else {
139		data->vdd = MCP3021_VDD_REF;
140	}
141
142	err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
143	if (err)
144		return err;
145
146	data->hwmon_dev = hwmon_device_register(&client->dev);
147	if (IS_ERR(data->hwmon_dev)) {
148		err = PTR_ERR(data->hwmon_dev);
149		goto exit_remove;
150	}
151
152	return 0;
153
154exit_remove:
155	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
156	return err;
157}
158
159static int mcp3021_remove(struct i2c_client *client)
160{
161	struct mcp3021_data *data = i2c_get_clientdata(client);
162
163	hwmon_device_unregister(data->hwmon_dev);
164	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
165
166	return 0;
167}
168
169static const struct i2c_device_id mcp3021_id[] = {
170	{ "mcp3021", mcp3021 },
171	{ "mcp3221", mcp3221 },
172	{ }
173};
174MODULE_DEVICE_TABLE(i2c, mcp3021_id);
175
176static struct i2c_driver mcp3021_driver = {
177	.driver = {
178		.name = "mcp3021",
179	},
180	.probe = mcp3021_probe,
181	.remove = mcp3021_remove,
182	.id_table = mcp3021_id,
183};
184
185module_i2c_driver(mcp3021_driver);
186
187MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
188MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
189MODULE_LICENSE("GPL");