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linux-next/drivers/hwmon/tmp102.c
Guenter Roeck d072543935 hwmon: (tmp102) Fix first temperature reading 
Commit 3d8f7a89a1 ("hwmon: (tmp102) Improve handling of initial read
delay") reduced the initial temperature read delay and made it dependent
on the chip's shutdown mode. If the chip was not in shutdown mode at probe,
the read delay no longer applies.

This ignores the fact that the chip initialization changes the temperature
sensor resolution, and that the temperature register values change when
the resolution is changed. As a result, the reported temperature is twice
as high as the real temperature until the first temperature conversion
after the configuration change is complete. This can result in unexpected
behavior and, worst case, in a system shutdown. To fix the problem,
let's just always wait for a conversion to complete before reporting
a temperature.

Fixes: 3d8f7a89a1 ("hwmon: (tmp102) Improve handling of initial read delay")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=197167
Reported-by: Ralf Goebel <ralf.goebel@imago-technologies.com>
Cc: Ralf Goebel <ralf.goebel@imago-technologies.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-10-24 06:17:14 -07:00

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/* Texas Instruments TMP102 SMBus temperature sensor driver
*
* Copyright (C) 2010 Steven King <sfking@fdwdc.com>
*
* 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/delay.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/jiffies.h>
#include <linux/regmap.h>
#include <linux/of.h>
#define DRIVER_NAME "tmp102"
#define TMP102_TEMP_REG 0x00
#define TMP102_CONF_REG 0x01
/* note: these bit definitions are byte swapped */
#define TMP102_CONF_SD 0x0100
#define TMP102_CONF_TM 0x0200
#define TMP102_CONF_POL 0x0400
#define TMP102_CONF_F0 0x0800
#define TMP102_CONF_F1 0x1000
#define TMP102_CONF_R0 0x2000
#define TMP102_CONF_R1 0x4000
#define TMP102_CONF_OS 0x8000
#define TMP102_CONF_EM 0x0010
#define TMP102_CONF_AL 0x0020
#define TMP102_CONF_CR0 0x0040
#define TMP102_CONF_CR1 0x0080
#define TMP102_TLOW_REG 0x02
#define TMP102_THIGH_REG 0x03
#define TMP102_CONFREG_MASK (TMP102_CONF_SD | TMP102_CONF_TM | \
TMP102_CONF_POL | TMP102_CONF_F0 | \
TMP102_CONF_F1 | TMP102_CONF_OS | \
TMP102_CONF_EM | TMP102_CONF_AL | \
TMP102_CONF_CR0 | TMP102_CONF_CR1)
#define TMP102_CONFIG_CLEAR (TMP102_CONF_SD | TMP102_CONF_OS | \
TMP102_CONF_CR0)
#define TMP102_CONFIG_SET (TMP102_CONF_TM | TMP102_CONF_EM | \
TMP102_CONF_CR1)
#define CONVERSION_TIME_MS 35 /* in milli-seconds */
struct tmp102 {
struct regmap *regmap;
u16 config_orig;
unsigned long ready_time;
};
/* convert left adjusted 13-bit TMP102 register value to milliCelsius */
static inline int tmp102_reg_to_mC(s16 val)
{
return ((val & ~0x01) * 1000) / 128;
}
/* convert milliCelsius to left adjusted 13-bit TMP102 register value */
static inline u16 tmp102_mC_to_reg(int val)
{
return (val * 128) / 1000;
}
static int tmp102_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *temp)
{
struct tmp102 *tmp102 = dev_get_drvdata(dev);
unsigned int regval;
int err, reg;
switch (attr) {
case hwmon_temp_input:
/* Is it too early to return a conversion ? */
if (time_before(jiffies, tmp102->ready_time)) {
dev_dbg(dev, "%s: Conversion not ready yet..\n", __func__);
return -EAGAIN;
}
reg = TMP102_TEMP_REG;
break;
case hwmon_temp_max_hyst:
reg = TMP102_TLOW_REG;
break;
case hwmon_temp_max:
reg = TMP102_THIGH_REG;
break;
default:
return -EOPNOTSUPP;
}
err = regmap_read(tmp102->regmap, reg, &regval);
if (err < 0)
return err;
*temp = tmp102_reg_to_mC(regval);
return 0;
}
static int tmp102_write(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long temp)
{
struct tmp102 *tmp102 = dev_get_drvdata(dev);
int reg;
switch (attr) {
case hwmon_temp_max_hyst:
reg = TMP102_TLOW_REG;
break;
case hwmon_temp_max:
reg = TMP102_THIGH_REG;
break;
default:
return -EOPNOTSUPP;
}
temp = clamp_val(temp, -256000, 255000);
return regmap_write(tmp102->regmap, reg, tmp102_mC_to_reg(temp));
}
static umode_t tmp102_is_visible(const void *data, enum hwmon_sensor_types type,
u32 attr, int channel)
{
if (type != hwmon_temp)
return 0;
switch (attr) {
case hwmon_temp_input:
return S_IRUGO;
case hwmon_temp_max_hyst:
case hwmon_temp_max:
return S_IRUGO | S_IWUSR;
default:
return 0;
}
}
static u32 tmp102_chip_config[] = {
HWMON_C_REGISTER_TZ,
0
};
static const struct hwmon_channel_info tmp102_chip = {
.type = hwmon_chip,
.config = tmp102_chip_config,
};
static u32 tmp102_temp_config[] = {
HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST,
0
};
static const struct hwmon_channel_info tmp102_temp = {
.type = hwmon_temp,
.config = tmp102_temp_config,
};
static const struct hwmon_channel_info *tmp102_info[] = {
&tmp102_chip,
&tmp102_temp,
NULL
};
static const struct hwmon_ops tmp102_hwmon_ops = {
.is_visible = tmp102_is_visible,
.read = tmp102_read,
.write = tmp102_write,
};
static const struct hwmon_chip_info tmp102_chip_info = {
.ops = &tmp102_hwmon_ops,
.info = tmp102_info,
};
static void tmp102_restore_config(void *data)
{
struct tmp102 *tmp102 = data;
regmap_write(tmp102->regmap, TMP102_CONF_REG, tmp102->config_orig);
}
static bool tmp102_is_writeable_reg(struct device *dev, unsigned int reg)
{
return reg != TMP102_TEMP_REG;
}
static bool tmp102_is_volatile_reg(struct device *dev, unsigned int reg)
{
return reg == TMP102_TEMP_REG;
}
static const struct regmap_config tmp102_regmap_config = {
.reg_bits = 8,
.val_bits = 16,
.max_register = TMP102_THIGH_REG,
.writeable_reg = tmp102_is_writeable_reg,
.volatile_reg = tmp102_is_volatile_reg,
.val_format_endian = REGMAP_ENDIAN_BIG,
.cache_type = REGCACHE_RBTREE,
.use_single_rw = true,
};
static int tmp102_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct tmp102 *tmp102;
unsigned int regval;
int err;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WORD_DATA)) {
dev_err(dev,
"adapter doesn't support SMBus word transactions\n");
return -ENODEV;
}
tmp102 = devm_kzalloc(dev, sizeof(*tmp102), GFP_KERNEL);
if (!tmp102)
return -ENOMEM;
i2c_set_clientdata(client, tmp102);
tmp102->regmap = devm_regmap_init_i2c(client, &tmp102_regmap_config);
if (IS_ERR(tmp102->regmap))
return PTR_ERR(tmp102->regmap);
err = regmap_read(tmp102->regmap, TMP102_CONF_REG, &regval);
if (err < 0) {
dev_err(dev, "error reading config register\n");
return err;
}
if ((regval & ~TMP102_CONFREG_MASK) !=
(TMP102_CONF_R0 | TMP102_CONF_R1)) {
dev_err(dev, "unexpected config register value\n");
return -ENODEV;
}
tmp102->config_orig = regval;
err = devm_add_action_or_reset(dev, tmp102_restore_config, tmp102);
if (err)
return err;
regval &= ~TMP102_CONFIG_CLEAR;
regval |= TMP102_CONFIG_SET;
err = regmap_write(tmp102->regmap, TMP102_CONF_REG, regval);
if (err < 0) {
dev_err(dev, "error writing config register\n");
return err;
}
/*
* Mark that we are not ready with data until the first
* conversion is complete
*/
tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
tmp102,
&tmp102_chip_info,
NULL);
if (IS_ERR(hwmon_dev)) {
dev_dbg(dev, "unable to register hwmon device\n");
return PTR_ERR(hwmon_dev);
}
dev_info(dev, "initialized\n");
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int tmp102_suspend(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct tmp102 *tmp102 = i2c_get_clientdata(client);
return regmap_update_bits(tmp102->regmap, TMP102_CONF_REG,
TMP102_CONF_SD, TMP102_CONF_SD);
}
static int tmp102_resume(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct tmp102 *tmp102 = i2c_get_clientdata(client);
int err;
err = regmap_update_bits(tmp102->regmap, TMP102_CONF_REG,
TMP102_CONF_SD, 0);
tmp102->ready_time = jiffies + msecs_to_jiffies(CONVERSION_TIME_MS);
return err;
}
#endif /* CONFIG_PM */
static SIMPLE_DEV_PM_OPS(tmp102_dev_pm_ops, tmp102_suspend, tmp102_resume);
static const struct i2c_device_id tmp102_id[] = {
{ "tmp102", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, tmp102_id);
static const struct of_device_id tmp102_of_match[] = {
{ .compatible = "ti,tmp102" },
{ },
};
MODULE_DEVICE_TABLE(of, tmp102_of_match);
static struct i2c_driver tmp102_driver = {
.driver.name = DRIVER_NAME,
.driver.of_match_table = of_match_ptr(tmp102_of_match),
.driver.pm = &tmp102_dev_pm_ops,
.probe = tmp102_probe,
.id_table = tmp102_id,
};
module_i2c_driver(tmp102_driver);
MODULE_AUTHOR("Steven King <sfking@fdwdc.com>");
MODULE_DESCRIPTION("Texas Instruments TMP102 temperature sensor driver");
MODULE_LICENSE("GPL");
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