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 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 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 55 static 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 80 static 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 85 static 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 } 100 101 static DEVICE_ATTR_RO(in0_input); 102 103 static 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; 163 164 exit_remove: 165 sysfs_remove_file(&client->dev.kobj, &dev_attr_in0_input.attr); 166 return err; 167 } 168 169 static 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 } 178 179 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 .remove = mcp3021_remove, 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