/* * An hwmon driver for the Microchip TC74 * * Copyright 2015 Maciej Szmigiero <mail@maciej.szmigiero.name> * * Based on ad7414.c: * Copyright 2006 Stefan Roese, DENX Software Engineering * Copyright 2008 Sean MacLennan, PIKA Technologies * Copyright 2008 Frank Edelhaeuser, Spansion Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ #include <linux/bitops.h> #include <linux/err.h> #include <linux/hwmon.h> #include <linux/hwmon-sysfs.h> #include <linux/i2c.h> #include <linux/jiffies.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/slab.h> #include <linux/sysfs.h> /* TC74 registers */ #define TC74_REG_TEMP 0x00 #define TC74_REG_CONFIG 0x01 struct tc74_data { struct i2c_client *client; struct mutex lock; /* atomic read data updates */ bool valid; /* validity of fields below */ unsigned long next_update; /* In jiffies */ s8 temp_input; /* Temp value in dC */ }; static int tc74_update_device(struct device *dev) { struct tc74_data *data = dev_get_drvdata(dev); struct i2c_client *client = data->client; int ret; ret = mutex_lock_interruptible(&data->lock); if (ret) return ret; if (time_after(jiffies, data->next_update) || !data->valid) { s32 value; value = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG); if (value < 0) { dev_dbg(&client->dev, "TC74_REG_CONFIG read err %d\n", (int)value); ret = value; goto ret_unlock; } if (!(value & BIT(6))) { /* not ready yet */ ret = -EAGAIN; goto ret_unlock; } value = i2c_smbus_read_byte_data(client, TC74_REG_TEMP); if (value < 0) { dev_dbg(&client->dev, "TC74_REG_TEMP read err %d\n", (int)value); ret = value; goto ret_unlock; } data->temp_input = value; data->next_update = jiffies + HZ / 4; data->valid = true; } ret_unlock: mutex_unlock(&data->lock); return ret; } static ssize_t show_temp_input(struct device *dev, struct device_attribute *attr, char *buf) { struct tc74_data *data = dev_get_drvdata(dev); int ret; ret = tc74_update_device(dev); if (ret) return ret; return sprintf(buf, "%d\n", data->temp_input * 1000); } static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0); static struct attribute *tc74_attrs[] = { &sensor_dev_attr_temp1_input.dev_attr.attr, NULL }; ATTRIBUTE_GROUPS(tc74); static int tc74_probe(struct i2c_client *client, const struct i2c_device_id *dev_id) { struct device *dev = &client->dev; struct tc74_data *data; struct device *hwmon_dev; s32 conf; if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)) return -EOPNOTSUPP; data = devm_kzalloc(dev, sizeof(struct tc74_data), GFP_KERNEL); if (!data) return -ENOMEM; data->client = client; mutex_init(&data->lock); /* Make sure the chip is powered up. */ conf = i2c_smbus_read_byte_data(client, TC74_REG_CONFIG); if (conf < 0) { dev_err(dev, "unable to read config register\n"); return conf; } if (conf & 0x3f) { dev_err(dev, "invalid config register value\n"); return -ENODEV; } if (conf & BIT(7)) { s32 ret; conf &= ~BIT(7); ret = i2c_smbus_write_byte_data(client, TC74_REG_CONFIG, conf); if (ret) dev_warn(dev, "unable to disable STANDBY\n"); } hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, data, tc74_groups); return PTR_ERR_OR_ZERO(hwmon_dev); } static const struct i2c_device_id tc74_id[] = { { "tc74", 0 }, {} }; MODULE_DEVICE_TABLE(i2c, tc74_id); static struct i2c_driver tc74_driver = { .driver = { .name = "tc74", }, .probe = tc74_probe, .id_table = tc74_id, }; module_i2c_driver(tc74_driver); MODULE_AUTHOR("Maciej Szmigiero <mail@maciej.szmigiero.name>"); MODULE_DESCRIPTION("TC74 driver"); MODULE_LICENSE("GPL");