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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * An hwmon driver for the Microchip TC744 *5 * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>6 *7 * Based on ad7414.c:8 * Copyright 2006 Stefan Roese, DENX Software Engineering9 * Copyright 2008 Sean MacLennan, PIKA Technologies10 * Copyright 2008 Frank Edelhaeuser, Spansion Inc.11 */12 13#include <linux/bitops.h>14#include <linux/err.h>15#include <linux/hwmon.h>16#include <linux/hwmon-sysfs.h>17#include <linux/i2c.h>18#include <linux/jiffies.h>19#include <linux/module.h>20#include <linux/mutex.h>21#include <linux/slab.h>22#include <linux/sysfs.h>23 24/* TC74 registers */25#define TC74_REG_TEMP 0x0026#define TC74_REG_CONFIG 0x0127 28struct tc74_data {29 struct i2c_client *client;30 struct mutex lock; /* atomic read data updates */31 bool valid; /* validity of fields below */32 unsigned long next_update; /* In jiffies */33 s8 temp_input; /* Temp value in dC */34};35 36static int tc74_update_device(struct device *dev)37{38 struct tc74_data *data = dev_get_drvdata(dev);39 struct i2c_client *client = data->client;40 int ret;41 42 ret = mutex_lock_interruptible(&data->lock);43 if (ret)44 return ret;45 46 if (time_after(jiffies, data->next_update) || !data->valid) {47 s32 value;48 49 value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);50 if (value < 0) {51 dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",52 (int)value);53 54 ret = value;55 goto ret_unlock;56 }57 58 if (!(value & BIT(6))) {59 /* not ready yet */60 61 ret = -EAGAIN;62 goto ret_unlock;63 }64 65 value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);66 if (value < 0) {67 dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",68 (int)value);69 70 ret = value;71 goto ret_unlock;72 }73 74 data->temp_input = value;75 data->next_update = jiffies + HZ / 4;76 data->valid = true;77 }78 79ret_unlock:80 mutex_unlock(&data->lock);81 82 return ret;83}84 85static ssize_t temp_input_show(struct device *dev,86 struct device_attribute *attr, char *buf)87{88 struct tc74_data *data = dev_get_drvdata(dev);89 int ret;90 91 ret = tc74_update_device(dev);92 if (ret)93 return ret;94 95 return sprintf(buf, "%d\n", data->temp_input * 1000);96}97static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);98 99static struct attribute *tc74_attrs[] = {100 &sensor_dev_attr_temp1_input.dev_attr.attr,101 NULL102};103 104ATTRIBUTE_GROUPS(tc74);105 106static int tc74_probe(struct i2c_client *client)107{108 struct device *dev = &client->dev;109 struct tc74_data *data;110 struct device *hwmon_dev;111 s32 conf;112 113 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))114 return -EOPNOTSUPP;115 116 data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);117 if (!data)118 return -ENOMEM;119 120 data->client = client;121 mutex_init(&data->lock);122 123 /* Make sure the chip is powered up. */124 conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);125 if (conf < 0) {126 dev_err(dev, "unable to read config register\n");127 128 return conf;129 }130 131 if (conf & 0x3f) {132 dev_err(dev, "invalid config register value\n");133 134 return -ENODEV;135 }136 137 if (conf & BIT(7)) {138 s32 ret;139 140 conf &= ~BIT(7);141 142 ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);143 if (ret)144 dev_warn(dev, "unable to disable STANDBY\n");145 }146 147 hwmon_dev = devm_hwmon_device_register_with_groups(dev,148 client->name,149 data, tc74_groups);150 return PTR_ERR_OR_ZERO(hwmon_dev);151}152 153static const struct i2c_device_id tc74_id[] = {154 { "tc74" },155 {}156};157MODULE_DEVICE_TABLE(i2c, tc74_id);158 159static struct i2c_driver tc74_driver = {160 .driver = {161 .name = "tc74",162 },163 .probe = tc74_probe,164 .id_table = tc74_id,165};166 167module_i2c_driver(tc74_driver);168 169MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");170 171MODULE_DESCRIPTION("TC74 driver");172MODULE_LICENSE("GPL");173