1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * mcp3021.c - driver for Microchip MCP3021 and MCP3221
  4 *
  5 * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
  6 * Author: Mingkai Hu <Mingkai.hu@freescale.com>
  7 * Reworked by Sven Schuchmann <schuchmann@schleissheimer.de>
  8 * DT support added by Clemens Gruber <clemens.gruber@pqgruber.com>
  9 *
 10 * This driver exports the value of analog input voltage to sysfs, the
 11 * voltage unit is mV. Through the sysfs interface, lm-sensors tool
 12 * can also display the input voltage.
 13 */
 14
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/hwmon.h>
 18#include <linux/slab.h>
 19#include <linux/i2c.h>
 20#include <linux/err.h>
 21#include <linux/device.h>
 22#include <linux/of.h>
 23
 24/* Vdd / reference voltage in millivolt */
 25#define MCP3021_VDD_REF_MAX	5500
 26#define MCP3021_VDD_REF_MIN	2700
 27#define MCP3021_VDD_REF_DEFAULT	3300
 28
 29/* output format */
 30#define MCP3021_SAR_SHIFT	2
 31#define MCP3021_SAR_MASK	0x3ff
 32#define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */
 33
 34#define MCP3221_SAR_SHIFT	0
 35#define MCP3221_SAR_MASK	0xfff
 36#define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */
 37
 38enum chips {
 39	mcp3021,
 40	mcp3221
 41};
 42
 43/*
 44 * Client data (each client gets its own)
 45 */
 46struct mcp3021_data {
 47	struct i2c_client *client;
 48	u32 vdd;        /* supply and reference voltage in millivolt */
 49	u16 sar_shift;
 50	u16 sar_mask;
 51	u8 output_res;
 52};
 53
 54static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
 55{
 56	return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
 57}
 58
 59static int mcp3021_read(struct device *dev, enum hwmon_sensor_types type,
 60			u32 attr, int channel, long *val)
 61{
 62	struct mcp3021_data *data = dev_get_drvdata(dev);
 63	struct i2c_client *client = data->client;
 64	__be16 buf;
 65	u16 reg;
 66	int ret;
 67
 68	if (type != hwmon_in)
 69		return -EOPNOTSUPP;
 70
 71	ret = i2c_master_recv(client, (char *)&buf, 2);
 72	if (ret < 0)
 73		return ret;
 74	if (ret != 2)
 75		return -EIO;
 76
 77	/* The output code of the MCP3021 is transmitted with MSB first. */
 78	reg = be16_to_cpu(buf);
 79
 80	/*
 81	 * The ten-bit output code is composed of the lower 4-bit of the
 82	 * first byte and the upper 6-bit of the second byte.
 83	 */
 84	reg = (reg >> data->sar_shift) & data->sar_mask;
 85
 86	*val = volts_from_reg(data, reg);
 87
 88	return 0;
 89}
 90
 91static umode_t mcp3021_is_visible(const void *_data,
 92				  enum hwmon_sensor_types type,
 93				  u32 attr, int channel)
 94{
 95	if (type != hwmon_in)
 96		return 0;
 97
 98	if (attr != hwmon_in_input)
 99		return 0;
100
101	return 0444;
102}
103
104static const struct hwmon_channel_info * const mcp3021_info[] = {
105	HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
106	NULL
107};
108
109static const struct hwmon_ops mcp3021_hwmon_ops = {
110	.is_visible = mcp3021_is_visible,
111	.read = mcp3021_read,
112};
113
114static const struct hwmon_chip_info mcp3021_chip_info = {
115	.ops = &mcp3021_hwmon_ops,
116	.info = mcp3021_info,
117};
118
119static const struct i2c_device_id mcp3021_id[];
120
121static int mcp3021_probe(struct i2c_client *client)
122{
123	struct mcp3021_data *data = NULL;
124	struct device_node *np = client->dev.of_node;
125	struct device *hwmon_dev;
126
127	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
128		return -ENODEV;
129
130	data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
131			    GFP_KERNEL);
132	if (!data)
133		return -ENOMEM;
134
135	i2c_set_clientdata(client, data);
136
137	if (np) {
138		if (!of_property_read_u32(np, "reference-voltage-microvolt",
139					  &data->vdd))
140			data->vdd /= 1000;
141		else
142			data->vdd = MCP3021_VDD_REF_DEFAULT;
143	} else {
144		u32 *pdata = dev_get_platdata(&client->dev);
145
146		if (pdata)
147			data->vdd = *pdata;
148		else
149			data->vdd = MCP3021_VDD_REF_DEFAULT;
150	}
151
152	switch (i2c_match_id(mcp3021_id, client)->driver_data) {
153	case mcp3021:
154		data->sar_shift = MCP3021_SAR_SHIFT;
155		data->sar_mask = MCP3021_SAR_MASK;
156		data->output_res = MCP3021_OUTPUT_RES;
157		break;
158
159	case mcp3221:
160		data->sar_shift = MCP3221_SAR_SHIFT;
161		data->sar_mask = MCP3221_SAR_MASK;
162		data->output_res = MCP3221_OUTPUT_RES;
163		break;
164	}
165
166	data->client = client;
167
168	if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
169		return -EINVAL;
170
171	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
172							 client->name,
173							 data,
174							 &mcp3021_chip_info,
175							 NULL);
176	return PTR_ERR_OR_ZERO(hwmon_dev);
177}
178
179static const struct i2c_device_id mcp3021_id[] = {
180	{ "mcp3021", mcp3021 },
181	{ "mcp3221", mcp3221 },
182	{ }
183};
184MODULE_DEVICE_TABLE(i2c, mcp3021_id);
185
186#ifdef CONFIG_OF
187static const struct of_device_id of_mcp3021_match[] = {
188	{ .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
189	{ .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
190	{ }
191};
192MODULE_DEVICE_TABLE(of, of_mcp3021_match);
193#endif
194
195static struct i2c_driver mcp3021_driver = {
196	.driver = {
197		.name = "mcp3021",
198		.of_match_table = of_match_ptr(of_mcp3021_match),
199	},
200	.probe = mcp3021_probe,
201	.id_table = mcp3021_id,
202};
203
204module_i2c_driver(mcp3021_driver);
205
206MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
207MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
208MODULE_LICENSE("GPL");