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 #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 39 enum chips { 40 mcp3021, 41 mcp3221 42 }; 43 44 /* 45 * Client data (each client gets its own) 46 */ 47 struct mcp3021_data { 48 struct i2c_client *client; 49 u32 vdd; /* supply and reference voltage in millivolt */ 50 u16 sar_shift; 51 u16 sar_mask; 52 u8 output_res; 53 }; 54 55 static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val) 56 { 57 return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res); 58 } 59 60 static int mcp3021_read(struct device *dev, enum hwmon_sensor_types type, 61 u32 attr, int channel, long *val) 62 { 63 struct mcp3021_data *data = dev_get_drvdata(dev); 64 struct i2c_client *client = data->client; 65 __be16 buf; 66 u16 reg; 67 int ret; 68 69 if (type != hwmon_in) 70 return -EOPNOTSUPP; 71 72 ret = i2c_master_recv(client, (char *)&buf, 2); 73 if (ret < 0) 74 return ret; 75 if (ret != 2) 76 return -EIO; 77 78 /* The output code of the MCP3021 is transmitted with MSB first. */ 79 reg = be16_to_cpu(buf); 80 81 /* 82 * The ten-bit output code is composed of the lower 4-bit of the 83 * first byte and the upper 6-bit of the second byte. 84 */ 85 reg = (reg >> data->sar_shift) & data->sar_mask; 86 87 *val = volts_from_reg(data, reg); 88 89 return 0; 90 } 91 92 static umode_t mcp3021_is_visible(const void *_data, 93 enum hwmon_sensor_types type, 94 u32 attr, int channel) 95 { 96 if (type != hwmon_in) 97 return 0; 98 99 if (attr != hwmon_in_input) 100 return 0; 101 102 return 0444; 103 } 104 105 static const struct hwmon_channel_info * const mcp3021_info[] = { 106 HWMON_CHANNEL_INFO(in, HWMON_I_INPUT), 107 NULL 108 }; 109 110 static const struct hwmon_ops mcp3021_hwmon_ops = { 111 .is_visible = mcp3021_is_visible, 112 .read = mcp3021_read, 113 }; 114 115 static const struct hwmon_chip_info mcp3021_chip_info = { 116 .ops = &mcp3021_hwmon_ops, 117 .info = mcp3021_info, 118 }; 119 120 static const struct i2c_device_id mcp3021_id[]; 121 122 static int mcp3021_probe(struct i2c_client *client) 123 { 124 struct mcp3021_data *data = NULL; 125 struct device_node *np = client->dev.of_node; 126 struct device *hwmon_dev; 127 128 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) 129 return -ENODEV; 130 131 data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data), 132 GFP_KERNEL); 133 if (!data) 134 return -ENOMEM; 135 136 i2c_set_clientdata(client, data); 137 138 if (np) { 139 if (!of_property_read_u32(np, "reference-voltage-microvolt", 140 &data->vdd)) 141 data->vdd /= 1000; 142 else 143 data->vdd = MCP3021_VDD_REF_DEFAULT; 144 } else { 145 u32 *pdata = dev_get_platdata(&client->dev); 146 147 if (pdata) 148 data->vdd = *pdata; 149 else 150 data->vdd = MCP3021_VDD_REF_DEFAULT; 151 } 152 153 switch (i2c_match_id(mcp3021_id, client)->driver_data) { 154 case mcp3021: 155 data->sar_shift = MCP3021_SAR_SHIFT; 156 data->sar_mask = MCP3021_SAR_MASK; 157 data->output_res = MCP3021_OUTPUT_RES; 158 break; 159 160 case mcp3221: 161 data->sar_shift = MCP3221_SAR_SHIFT; 162 data->sar_mask = MCP3221_SAR_MASK; 163 data->output_res = MCP3221_OUTPUT_RES; 164 break; 165 } 166 167 data->client = client; 168 169 if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN) 170 return -EINVAL; 171 172 hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, 173 client->name, 174 data, 175 &mcp3021_chip_info, 176 NULL); 177 return PTR_ERR_OR_ZERO(hwmon_dev); 178 } 179 180 static const struct i2c_device_id mcp3021_id[] = { 181 { "mcp3021", mcp3021 }, 182 { "mcp3221", mcp3221 }, 183 { } 184 }; 185 MODULE_DEVICE_TABLE(i2c, mcp3021_id); 186 187 #ifdef CONFIG_OF 188 static const struct of_device_id of_mcp3021_match[] = { 189 { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 }, 190 { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 }, 191 { } 192 }; 193 MODULE_DEVICE_TABLE(of, of_mcp3021_match); 194 #endif 195 196 static struct i2c_driver mcp3021_driver = { 197 .driver = { 198 .name = "mcp3021", 199 .of_match_table = of_match_ptr(of_mcp3021_match), 200 }, 201 .probe_new = mcp3021_probe, 202 .id_table = mcp3021_id, 203 }; 204 205 module_i2c_driver(mcp3021_driver); 206 207 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>"); 208 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver"); 209 MODULE_LICENSE("GPL"); 210