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 export 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#include <linux/of_device.h>
 24
 25/* Vdd / reference voltage in millivolt */
 26#define MCP3021_VDD_REF_MAX	5500
 27#define MCP3021_VDD_REF_MIN	2700
 28#define MCP3021_VDD_REF_DEFAULT	3300
 29
 30/* output format */
 31#define MCP3021_SAR_SHIFT	2
 32#define MCP3021_SAR_MASK	0x3ff
 33#define MCP3021_OUTPUT_RES	10	/* 10-bit resolution */
 34
 35#define MCP3221_SAR_SHIFT	0
 36#define MCP3221_SAR_MASK	0xfff
 37#define MCP3221_OUTPUT_RES	12	/* 12-bit resolution */
 38
 39enum chips {
 40	mcp3021,
 41	mcp3221
 42};
 43
 44/*
 45 * Client data (each client gets its own)
 46 */
 47struct mcp3021_data {
 48	struct device *hwmon_dev;
 49	u32 vdd;        /* supply and reference voltage in millivolt */
 50	u16 sar_shift;
 51	u16 sar_mask;
 52	u8 output_res;
 53};
 54
 55static int mcp3021_read16(struct i2c_client *client)
 56{
 57	struct mcp3021_data *data = i2c_get_clientdata(client);
 58	int ret;
 59	u16 reg;
 60	__be16 buf;
 61
 62	ret = i2c_master_recv(client, (char *)&buf, 2);
 63	if (ret < 0)
 64		return ret;
 65	if (ret != 2)
 66		return -EIO;
 67
 68	/* The output code of the MCP3021 is transmitted with MSB first. */
 69	reg = be16_to_cpu(buf);
 70
 71	/*
 72	 * The ten-bit output code is composed of the lower 4-bit of the
 73	 * first byte and the upper 6-bit of the second byte.
 74	 */
 75	reg = (reg >> data->sar_shift) & data->sar_mask;
 76
 77	return reg;
 78}
 79
 80static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
 81{
 82	return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
 83}
 84
 85static ssize_t in0_input_show(struct device *dev,
 86			      struct device_attribute *attr, char *buf)
 87{
 88	struct i2c_client *client = to_i2c_client(dev);
 89	struct mcp3021_data *data = i2c_get_clientdata(client);
 90	int reg, in_input;
 91
 92	reg = mcp3021_read16(client);
 93	if (reg < 0)
 94		return reg;
 95
 96	in_input = volts_from_reg(data, reg);
 97
 98	return sprintf(buf, "%d\n", in_input);
 99}
100
101static DEVICE_ATTR_RO(in0_input);
102
103static int mcp3021_probe(struct i2c_client *client,
104				const struct i2c_device_id *id)
105{
106	int err;
107	struct mcp3021_data *data = NULL;
108	struct device_node *np = client->dev.of_node;
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	if (np) {
121		if (!of_property_read_u32(np, "reference-voltage-microvolt",
122					  &data->vdd))
123			data->vdd /= 1000;
124		else
125			data->vdd = MCP3021_VDD_REF_DEFAULT;
126	} else {
127		u32 *pdata = dev_get_platdata(&client->dev);
128
129		if (pdata)
130			data->vdd = *pdata;
131		else
132			data->vdd = MCP3021_VDD_REF_DEFAULT;
133	}
134
135	switch (id->driver_data) {
136	case mcp3021:
137		data->sar_shift = MCP3021_SAR_SHIFT;
138		data->sar_mask = MCP3021_SAR_MASK;
139		data->output_res = MCP3021_OUTPUT_RES;
140		break;
141
142	case mcp3221:
143		data->sar_shift = MCP3221_SAR_SHIFT;
144		data->sar_mask = MCP3221_SAR_MASK;
145		data->output_res = MCP3221_OUTPUT_RES;
146		break;
147	}
148
149	if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
150		return -EINVAL;
151
152	err = sysfs_create_file(&client->dev.kobj, &dev_attr_in0_input.attr);
153	if (err)
154		return err;
155
156	data->hwmon_dev = hwmon_device_register(&client->dev);
157	if (IS_ERR(data->hwmon_dev)) {
158		err = PTR_ERR(data->hwmon_dev);
159		goto exit_remove;
160	}
161
162	return 0;
163
164exit_remove:
165	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
166	return err;
167}
168
169static int mcp3021_remove(struct i2c_client *client)
170{
171	struct mcp3021_data *data = i2c_get_clientdata(client);
172
173	hwmon_device_unregister(data->hwmon_dev);
174	sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr);
175
176	return 0;
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	.remove = mcp3021_remove,
202	.id_table = mcp3021_id,
203};
204
205module_i2c_driver(mcp3021_driver);
206
207MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>");
208MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
209MODULE_LICENSE("GPL");