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 38 enum chips { 39 mcp3021, 40 mcp3221 41 }; 42 43 /* 44 * Client data (each client gets its own) 45 */ 46 struct 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 54 static 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 59 static 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 91 static 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 } 103 104 static const struct hwmon_channel_info * const mcp3021_info[] = { 105 HWMON_CHANNEL_INFO(in, HWMON_I_INPUT), 106 NULL 107 }; 108 109 static const struct hwmon_ops mcp3021_hwmon_ops = { 110 .is_visible = mcp3021_is_visible, 111 .read = mcp3021_read, 112 }; 113 114 static const struct hwmon_chip_info mcp3021_chip_info = { 115 .ops = &mcp3021_hwmon_ops, 116 .info = mcp3021_info, 117 }; 118 119 static const struct i2c_device_id mcp3021_id[]; 120 121 static 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 } 178 179 static const struct i2c_device_id mcp3021_id[] = { 180 { "mcp3021", mcp3021 }, 181 { "mcp3221", mcp3221 }, 182 { } 183 }; 184 MODULE_DEVICE_TABLE(i2c, mcp3021_id); 185 186 #ifdef CONFIG_OF 187 static const struct of_device_id of_mcp3021_match[] = { 188 { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 }, 189 { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 }, 190 { } 191 }; 192 MODULE_DEVICE_TABLE(of, of_mcp3021_match); 193 #endif 194 195 static 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 }; 203 204 module_i2c_driver(mcp3021_driver); 205 206 MODULE_AUTHOR("Mingkai Hu <Mingkai.hu@freescale.com>"); 207 MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver"); 208 MODULE_LICENSE("GPL"); 209