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linux-next/drivers/hwmon/lm77.c
Axel Lin 99765db299 hwmon: (lm77) Prevent overflow problem when writing large limits 
On platforms with sizeof(int) < sizeof(long), writing a temperature
limit larger than MAXINT will result in unpredictable limit values
written to the chip.
Clamp the input values to the supported limits first to fix the problem.

For set_temp_hyst:
As Guenter pointed out that the temperature is read as unsigned and stored in
an unsigned long. This is wrong; nothing in the datasheet suggests that the
value (the absolute temperature) must be positive.
So change it to signed.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2014-07-31 09:41:46 -07:00

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/*
* lm77.c - Part of lm_sensors, Linux kernel modules for hardware
* monitoring
*
* Copyright (c) 2004 Andras BALI <drewie@freemail.hu>
*
* Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>. The LM77
* is a temperature sensor and thermal window comparator with 0.5 deg
* resolution made by National Semiconductor. Complete datasheet can be
* obtained at their site:
* http://www.national.com/pf/LM/LM77.html
*
* 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.
*/
#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>
/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
I2C_CLIENT_END };
/* The LM77 registers */
#define LM77_REG_TEMP 0x00
#define LM77_REG_CONF 0x01
#define LM77_REG_TEMP_HYST 0x02
#define LM77_REG_TEMP_CRIT 0x03
#define LM77_REG_TEMP_MIN 0x04
#define LM77_REG_TEMP_MAX 0x05
enum temp_index {
t_input = 0,
t_crit,
t_min,
t_max,
t_hyst,
t_num_temp
};
static const u8 temp_regs[t_num_temp] = {
[t_input] = LM77_REG_TEMP,
[t_min] = LM77_REG_TEMP_MIN,
[t_max] = LM77_REG_TEMP_MAX,
[t_crit] = LM77_REG_TEMP_CRIT,
[t_hyst] = LM77_REG_TEMP_HYST,
};
/* Each client has this additional data */
struct lm77_data {
struct i2c_client *client;
struct mutex update_lock;
char valid;
unsigned long last_updated; /* In jiffies */
int temp[t_num_temp]; /* index using temp_index */
u8 alarms;
};
/* straight from the datasheet */
#define LM77_TEMP_MIN (-55000)
#define LM77_TEMP_MAX 125000
/*
* In the temperature registers, the low 3 bits are not part of the
* temperature values; they are the status bits.
*/
static inline s16 LM77_TEMP_TO_REG(int temp)
{
return (temp / 500) * 8;
}
static inline int LM77_TEMP_FROM_REG(s16 reg)
{
return (reg / 8) * 500;
}
/*
* All registers are word-sized, except for the configuration register.
* The LM77 uses the high-byte first convention.
*/
static u16 lm77_read_value(struct i2c_client *client, u8 reg)
{
if (reg == LM77_REG_CONF)
return i2c_smbus_read_byte_data(client, reg);
else
return i2c_smbus_read_word_swapped(client, reg);
}
static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
{
if (reg == LM77_REG_CONF)
return i2c_smbus_write_byte_data(client, reg, value);
else
return i2c_smbus_write_word_swapped(client, reg, value);
}
static struct lm77_data *lm77_update_device(struct device *dev)
{
struct lm77_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
int i;
mutex_lock(&data->update_lock);
if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
|| !data->valid) {
dev_dbg(&client->dev, "Starting lm77 update\n");
for (i = 0; i < t_num_temp; i++) {
data->temp[i] =
LM77_TEMP_FROM_REG(lm77_read_value(client,
temp_regs[i]));
}
data->alarms =
lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
data->last_updated = jiffies;
data->valid = 1;
}
mutex_unlock(&data->update_lock);
return data;
}
/* sysfs stuff */
static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
struct lm77_data *data = lm77_update_device(dev);
return sprintf(buf, "%d\n", data->temp[attr->index]);
}
static ssize_t show_temp_hyst(struct device *dev,
struct device_attribute *devattr, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
struct lm77_data *data = lm77_update_device(dev);
int nr = attr->index;
int temp;
temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
data->temp[nr] - data->temp[t_hyst];
return sprintf(buf, "%d\n", temp);
}
static ssize_t set_temp(struct device *dev, struct device_attribute *devattr,
const char *buf, size_t count)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
struct lm77_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
int nr = attr->index;
long val;
int err;
err = kstrtol(buf, 10, &val);
if (err)
return err;
val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
mutex_lock(&data->update_lock);
data->temp[nr] = val;
lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
mutex_unlock(&data->update_lock);
return count;
}
/*
* hysteresis is stored as a relative value on the chip, so it has to be
* converted first.
*/
static ssize_t set_temp_hyst(struct device *dev,
struct device_attribute *devattr,
const char *buf, size_t count)
{
struct lm77_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
err = kstrtol(buf, 10, &val);
if (err)
return err;
mutex_lock(&data->update_lock);
val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
data->temp[t_hyst] = val;
lm77_write_value(client, LM77_REG_TEMP_HYST,
LM77_TEMP_TO_REG(data->temp[t_hyst]));
mutex_unlock(&data->update_lock);
return count;
}
static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
char *buf)
{
int bitnr = to_sensor_dev_attr(attr)->index;
struct lm77_data *data = lm77_update_device(dev);
return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
}
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input);
static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp, set_temp,
t_crit);
static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp, set_temp,
t_min);
static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp, set_temp,
t_max);
static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp_hyst,
set_temp_hyst, t_crit);
static SENSOR_DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp_hyst, NULL, t_min);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max);
static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);
static struct attribute *lm77_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_temp1_crit.dev_attr.attr,
&sensor_dev_attr_temp1_min.dev_attr.attr,
&sensor_dev_attr_temp1_max.dev_attr.attr,
&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
&sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
NULL
};
ATTRIBUTE_GROUPS(lm77);
/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
{
struct i2c_adapter *adapter = client->adapter;
int i, cur, conf, hyst, crit, min, max;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV;
/*
* Here comes the remaining detection. Since the LM77 has no
* register dedicated to identification, we have to rely on the
* following tricks:
*
* 1. the high 4 bits represent the sign and thus they should
* always be the same
* 2. the high 3 bits are unused in the configuration register
* 3. addresses 0x06 and 0x07 return the last read value
* 4. registers cycling over 8-address boundaries
*
* Word-sized registers are high-byte first.
*/
/* addresses cycling */
cur = i2c_smbus_read_word_data(client, 0);
conf = i2c_smbus_read_byte_data(client, 1);
hyst = i2c_smbus_read_word_data(client, 2);
crit = i2c_smbus_read_word_data(client, 3);
min = i2c_smbus_read_word_data(client, 4);
max = i2c_smbus_read_word_data(client, 5);
for (i = 8; i <= 0xff; i += 8) {
if (i2c_smbus_read_byte_data(client, i + 1) != conf
|| i2c_smbus_read_word_data(client, i + 2) != hyst
|| i2c_smbus_read_word_data(client, i + 3) != crit
|| i2c_smbus_read_word_data(client, i + 4) != min
|| i2c_smbus_read_word_data(client, i + 5) != max)
return -ENODEV;
}
/* sign bits */
if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
|| ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
|| ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
|| ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
|| ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
return -ENODEV;
/* unused bits */
if (conf & 0xe0)
return -ENODEV;
/* 0x06 and 0x07 return the last read value */
cur = i2c_smbus_read_word_data(client, 0);
if (i2c_smbus_read_word_data(client, 6) != cur
|| i2c_smbus_read_word_data(client, 7) != cur)
return -ENODEV;
hyst = i2c_smbus_read_word_data(client, 2);
if (i2c_smbus_read_word_data(client, 6) != hyst
|| i2c_smbus_read_word_data(client, 7) != hyst)
return -ENODEV;
min = i2c_smbus_read_word_data(client, 4);
if (i2c_smbus_read_word_data(client, 6) != min
|| i2c_smbus_read_word_data(client, 7) != min)
return -ENODEV;
strlcpy(info->type, "lm77", I2C_NAME_SIZE);
return 0;
}
static void lm77_init_client(struct i2c_client *client)
{
/* Initialize the LM77 chip - turn off shutdown mode */
int conf = lm77_read_value(client, LM77_REG_CONF);
if (conf & 1)
lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
}
static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct lm77_data *data;
data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
mutex_init(&data->update_lock);
/* Initialize the LM77 chip */
lm77_init_client(client);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
data, lm77_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id lm77_id[] = {
{ "lm77", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, lm77_id);
/* This is the driver that will be inserted */
static struct i2c_driver lm77_driver = {
.class = I2C_CLASS_HWMON,
.driver = {
.name = "lm77",
},
.probe = lm77_probe,
.id_table = lm77_id,
.detect = lm77_detect,
.address_list = normal_i2c,
};
module_i2c_driver(lm77_driver);
MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
MODULE_DESCRIPTION("LM77 driver");
MODULE_LICENSE("GPL");
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