diff options
Diffstat (limited to 'drivers/hwmon/max127.c')
| -rw-r--r-- | drivers/hwmon/max127.c | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/drivers/hwmon/max127.c b/drivers/hwmon/max127.c new file mode 100644 index 000000000000..a223f94f56cc --- /dev/null +++ b/drivers/hwmon/max127.c @@ -0,0 +1,312 @@ +/* + * max127.c - Part of lm_sensors, Linux kernel modules for hardware + * monitoring + * Copyright 2004-present Facebook. All Rights Reserved. + * Copyright (C) 2003-2004 Alexey Fisher <fishor@mail.ru> + * Jean Delvare <khali@linux-fr.org> + * + * Based on the max1619 driver, which was based on the lm90 driver. + * The MAX127 is a voltage sensor chip made by Maxim. It reports + * up to eight voltages, with a choice of maximums * of 5V or 10V. + * In addition, it can read either only positive voltages, + * or negative voltages as well, for a maximum range of -10V to +10V. + * + * Complete datasheet can be obtained from Maxim's website at: + * http://datasheets.maximintegrated.com/en/ds/MAX127-MAX128B.pdf + * + * 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/jiffies.h> +#include <linux/i2c.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/err.h> +#include <linux/mutex.h> +#include <linux/sysfs.h> + +static const unsigned short normal_i2c[] = { + 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, I2C_CLIENT_END }; + +/* + * Insmod parameters + */ + +I2C_CLIENT_INSMOD_1(max127); + +static int scaling; +module_param(scaling, int, 0); +MODULE_PARM_DESC(scaling, "Fixed-point scaling factor (* 10000), ie 24414"); + + +/* + * The MAX127 I2C messages + */ + +/* We send a single query byte to the device, setting the following bits: */ + +#define MAX127_REG_R_START 0x80 /* Top bit must be set */ +#define MAX127_REG_R_SEL_MASK 0x70 /* Which of 8 inputs to get */ +#define MAX127_REG_R_SEL_SHIFT 4 +#define MAX127_REG_R_RNG 0x08 /* 10v (otherwise 5v) */ +#define MAX127_REG_R_BIP 0x04 /* show negative voltage */ +#define MAX127_REG_R_PD1 0x02 /* power saving controls */ +#define MAX127_REG_R_PD0 0x01 + +/* Must shift return value to get a 12-bit value */ +#define MAX127_RESULT_SHIFT 4 + +#define MAX127_CHANNELS 8 + +/* + * Functions declaration + */ + +static int max127_probe(struct i2c_client *client, + const struct i2c_device_id *id); +static int max127_detect(struct i2c_client *client, int kind, + struct i2c_board_info *info); +static int max127_remove(struct i2c_client *client); +static void max127_update_device(struct device *dev, int which); + +/* + * Driver data (common to all clients) + */ + +static const struct i2c_device_id max127_id[] = { + { "max127", max127 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max127_id); + +static struct i2c_driver max127_driver = { + .class = I2C_CLASS_HWMON, + .driver = { + .name = "max127", + }, + .probe = max127_probe, + .remove = max127_remove, + .id_table = max127_id, + .detect = max127_detect, + .address_data = &addr_data, +}; + +/* + * Client data (each client gets its own) + */ + +struct max127_data { + struct device *hwmon_dev; + struct mutex update_lock; + u16 valid; /* zero until following fields are valid */ + + u16 voltage; +}; + +/* + * Sysfs stuff + */ + +static ssize_t show_in(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct max127_data *data = i2c_get_clientdata(client); + struct sensor_device_attribute *sensor_attr = to_sensor_dev_attr(attr); + int which = sensor_attr->index; + int valid; + unsigned voltage; + + mutex_lock(&data->update_lock); + max127_update_device(dev, which); + valid = data->valid; + voltage = data->voltage; + mutex_unlock(&data->update_lock); + + if (scaling) + voltage = voltage * scaling / 10000; + + if (!valid) + return -EIO; + return sprintf(buf, "%u\n", voltage); +} + + +static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_in, NULL, 0); +static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_in, NULL, 1); +static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_in, NULL, 2); +static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_in, NULL, 3); +static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_in, NULL, 4); +static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_in, NULL, 5); +static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_in, NULL, 6); +static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_in, NULL, 7); + +static struct attribute *max127_attributes[] = { + &sensor_dev_attr_in0_input.dev_attr.attr, + &sensor_dev_attr_in1_input.dev_attr.attr, + &sensor_dev_attr_in2_input.dev_attr.attr, + &sensor_dev_attr_in3_input.dev_attr.attr, + &sensor_dev_attr_in4_input.dev_attr.attr, + &sensor_dev_attr_in5_input.dev_attr.attr, + &sensor_dev_attr_in6_input.dev_attr.attr, + &sensor_dev_attr_in7_input.dev_attr.attr, + NULL +}; + +static const struct attribute_group max127_group = { + .attrs = max127_attributes, +}; + +/* + * Real code + */ + +/* Return 0 if detection is successful, -ENODEV otherwise */ +static int max127_detect(struct i2c_client *new_client, int kind, + struct i2c_board_info *info) +{ + struct i2c_adapter *adapter = new_client->adapter; + + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | + I2C_FUNC_SMBUS_WORD_DATA)) + return -EIO; + + /* + * We don't currently do any detection of the MAX127, although + * presumably we could try setting and unsetting the top + * bit in a query to see whether it does conversions or fails. + */ + + strlcpy(info->type, "max127", I2C_NAME_SIZE); + + return 0; +} + +static int max127_probe(struct i2c_client *new_client, + const struct i2c_device_id *id) +{ + struct max127_data *data; + int err; + + data = kzalloc(sizeof(struct max127_data), GFP_KERNEL); + if (!data) { + err = -ENOMEM; + goto exit; + } + + i2c_set_clientdata(new_client, data); + data->valid = 0; + mutex_init(&data->update_lock); + + /* Register sysfs hooks */ + if ((err = sysfs_create_group(&new_client->dev.kobj, &max127_group))) + goto exit_free; + + data->hwmon_dev = hwmon_device_register(&new_client->dev); + if (IS_ERR(data->hwmon_dev)) { + err = PTR_ERR(data->hwmon_dev); + goto exit_remove_files; + } + + return 0; + +exit_remove_files: + sysfs_remove_group(&new_client->dev.kobj, &max127_group); +exit_free: + kfree(data); +exit: + return err; +} + +static int max127_remove(struct i2c_client *client) +{ + struct max127_data *data = i2c_get_clientdata(client); + + hwmon_device_unregister(data->hwmon_dev); + sysfs_remove_group(&client->dev.kobj, &max127_group); + + kfree(data); + return 0; +} + +static void max127_update_device(struct device *dev, int which) +{ + struct i2c_client *client = to_i2c_client(dev); + struct max127_data *data = i2c_get_clientdata(client); + struct i2c_msg msg; + int status; + u8 buf[2]; + + /* + * The MAX127 doesn't use standard SMBus queries; it needs a + * write to specify what conversion to make, followed by an i2c + * STOP. It can then be read for the two-byte voltage value. + * Perhaps the idea is that a query can be started, then + * checked at an arbitrarily later time. We don't support + * that -- we just get a result immediately. + * + * We have to use i2c_transfer to do the second read without + * writing to any registers, rather than using the i2c_smbus_xxxxxx + * queries that most of the other hwmon drivers do. + */ + + dev_dbg(&client->dev, "Updating max127 data for probe %d.\n", which); + data->valid = 0; + + buf[0] = MAX127_REG_R_START | (which << MAX127_REG_R_SEL_SHIFT) | + MAX127_REG_R_RNG; + msg.addr = client->addr; + msg.flags = 0; + msg.buf = buf; + msg.len = 1; + status = i2c_transfer(client->adapter, &msg, 1); + + if (status != 1) { + return; + } + + msg.addr = client->addr; + msg.flags = I2C_M_RD; + msg.buf = buf; + msg.len = 2; + status = i2c_transfer(client->adapter, &msg, 1); + + data->voltage = (buf[0] << 8) | buf[1]; + data->voltage >>= MAX127_RESULT_SHIFT; + + if (status == 1) + data->valid = 1; +} + +static int __init sensors_max127_init(void) +{ + return i2c_add_driver(&max127_driver); +} + +static void __exit sensors_max127_exit(void) +{ + i2c_del_driver(&max127_driver); +} + +MODULE_AUTHOR("Kevin Lahey <klahey@fb.com>"); +MODULE_DESCRIPTION("MAX127 sensor driver"); +MODULE_LICENSE("GPL"); + +module_init(sensors_max127_init); +module_exit(sensors_max127_exit); |