drivers/hwmon/tc74.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * An hwmon driver for the Microchip TC74
0004  *
0005  * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name>
0006  *
0007  * Based on ad7414.c:
0008  *  Copyright 2006 Stefan Roese, DENX Software Engineering
0009  *  Copyright 2008 Sean MacLennan, PIKA Technologies
0010  *  Copyright 2008 Frank Edelhaeuser, Spansion Inc.
0011  */
0012
0013 #include <linux/bitops.h>
0014 #include <linux/err.h>
0015 #include <linux/hwmon.h>
0016 #include <linux/hwmon-sysfs.h>
0017 #include <linux/i2c.h>
0018 #include <linux/jiffies.h>
0019 #include <linux/module.h>
0020 #include <linux/mutex.h>
0021 #include <linux/slab.h>
0022 #include <linux/sysfs.h>
0023
0024 /* TC74 registers */
0025 #define TC74_REG_TEMP       0x00
0026 #define TC74_REG_CONFIG     0x01
0027
0028 struct tc74_data {
0029     struct i2c_client   *client;
0030     struct mutex        lock;   /* atomic read data updates */
0031     bool            valid;  /* validity of fields below */
0032     unsigned long       next_update;    /* In jiffies */
0033     s8          temp_input; /* Temp value in dC */
0034 };
0035
0036 static int tc74_update_device(struct device *dev)
0037 {
0038     struct tc74_data *data = dev_get_drvdata(dev);
0039     struct i2c_client *client = data->client;
0040     int ret;
0041
0042     ret = mutex_lock_interruptible(&data->lock);
0043     if (ret)
0044         return ret;
0045
0046     if (time_after(jiffies, data->next_update) || !data->valid) {
0047         s32 value;
0048
0049         value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
0050         if (value < 0) {
0051             dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n",
0052                 (int)value);
0053
0054             ret = value;
0055             goto ret_unlock;
0056         }
0057
0058         if (!(value & BIT(6))) {
0059             /* not ready yet */
0060
0061             ret = -EAGAIN;
0062             goto ret_unlock;
0063         }
0064
0065         value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP);
0066         if (value < 0) {
0067             dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n",
0068                 (int)value);
0069
0070             ret = value;
0071             goto ret_unlock;
0072         }
0073
0074         data->temp_input = value;
0075         data->next_update = jiffies + HZ / 4;
0076         data->valid = true;
0077     }
0078
0079 ret_unlock:
0080     mutex_unlock(&data->lock);
0081
0082     return ret;
0083 }
0084
0085 static ssize_t temp_input_show(struct device *dev,
0086                    struct device_attribute *attr, char *buf)
0087 {
0088     struct tc74_data *data = dev_get_drvdata(dev);
0089     int ret;
0090
0091     ret = tc74_update_device(dev);
0092     if (ret)
0093         return ret;
0094
0095     return sprintf(buf, "%d\n", data->temp_input * 1000);
0096 }
0097 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
0098
0099 static struct attribute *tc74_attrs[] = {
0100     &sensor_dev_attr_temp1_input.dev_attr.attr,
0101     NULL
0102 };
0103
0104 ATTRIBUTE_GROUPS(tc74);
0105
0106 static int tc74_probe(struct i2c_client *client)
0107 {
0108     struct device *dev = &client->dev;
0109     struct tc74_data *data;
0110     struct device *hwmon_dev;
0111     s32 conf;
0112
0113     if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
0114         return -EOPNOTSUPP;
0115
0116     data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL);
0117     if (!data)
0118         return -ENOMEM;
0119
0120     data->client = client;
0121     mutex_init(&data->lock);
0122
0123     /* Make sure the chip is powered up. */
0124     conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG);
0125     if (conf < 0) {
0126         dev_err(dev, "unable to read config register\n");
0127
0128         return conf;
0129     }
0130
0131     if (conf & 0x3f) {
0132         dev_err(dev, "invalid config register value\n");
0133
0134         return -ENODEV;
0135     }
0136
0137     if (conf & BIT(7)) {
0138         s32 ret;
0139
0140         conf &= ~BIT(7);
0141
0142         ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf);
0143         if (ret)
0144             dev_warn(dev, "unable to disable STANDBY\n");
0145     }
0146
0147     hwmon_dev = devm_hwmon_device_register_with_groups(dev,
0148                                client->name,
0149                                data, tc74_groups);
0150     return PTR_ERR_OR_ZERO(hwmon_dev);
0151 }
0152
0153 static const struct i2c_device_id tc74_id[] = {
0154     { "tc74", 0 },
0155     {}
0156 };
0157 MODULE_DEVICE_TABLE(i2c, tc74_id);
0158
0159 static struct i2c_driver tc74_driver = {
0160     .driver = {
0161         .name   = "tc74",
0162     },
0163     .probe_new = tc74_probe,
0164     .id_table = tc74_id,
0165 };
0166
0167 module_i2c_driver(tc74_driver);
0168
0169 MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>");
0170
0171 MODULE_DESCRIPTION("TC74 driver");
0172 MODULE_LICENSE("GPL");