mirror of
https://github.com/torvalds/linux.git
synced 2024-12-05 02:23:16 +00:00
8efd10147c
Add hardware monitoring driver for the Maxim MAX127 chip. MAX127 min/max range handling code is inspired by the max197 driver. Signed-off-by: Tao Ren <rentao.bupt@gmail.com> Link: https://lore.kernel.org/r/20201123185658.7632-2-rentao.bupt@gmail.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
353 lines
7.5 KiB
C
353 lines
7.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
||
/*
|
||
* Hardware monitoring driver for MAX127.
|
||
*
|
||
* Copyright (c) 2020 Facebook Inc.
|
||
*/
|
||
|
||
#include <linux/err.h>
|
||
#include <linux/hwmon.h>
|
||
#include <linux/i2c.h>
|
||
#include <linux/init.h>
|
||
#include <linux/module.h>
|
||
|
||
/*
|
||
* MAX127 Control Byte. Refer to MAX127 datasheet, Table 1 "Control-Byte
|
||
* Format" for details.
|
||
*/
|
||
#define MAX127_CTRL_START BIT(7)
|
||
#define MAX127_CTRL_SEL_SHIFT 4
|
||
#define MAX127_CTRL_RNG BIT(3)
|
||
#define MAX127_CTRL_BIP BIT(2)
|
||
#define MAX127_CTRL_PD1 BIT(1)
|
||
#define MAX127_CTRL_PD0 BIT(0)
|
||
|
||
#define MAX127_NUM_CHANNELS 8
|
||
#define MAX127_SET_CHANNEL(ch) (((ch) & 7) << MAX127_CTRL_SEL_SHIFT)
|
||
|
||
/*
|
||
* MAX127 channel input ranges. Refer to MAX127 datasheet, Table 3 "Range
|
||
* and Polarity Selection" for details.
|
||
*/
|
||
#define MAX127_FULL_RANGE 10000 /* 10V */
|
||
#define MAX127_HALF_RANGE 5000 /* 5V */
|
||
|
||
/*
|
||
* MAX127 returns 2 bytes at read:
|
||
* - the first byte contains data[11:4].
|
||
* - the second byte contains data[3:0] (MSB) and 4 dummy 0s (LSB).
|
||
* Refer to MAX127 datasheet, "Read a Conversion (Read Cycle)" section
|
||
* for details.
|
||
*/
|
||
#define MAX127_DATA_LEN 2
|
||
#define MAX127_DATA_SHIFT 4
|
||
|
||
#define MAX127_SIGN_BIT BIT(11)
|
||
|
||
struct max127_data {
|
||
struct mutex lock;
|
||
struct i2c_client *client;
|
||
u8 ctrl_byte[MAX127_NUM_CHANNELS];
|
||
};
|
||
|
||
static int max127_select_channel(struct i2c_client *client, u8 ctrl_byte)
|
||
{
|
||
int status;
|
||
struct i2c_msg msg = {
|
||
.addr = client->addr,
|
||
.flags = 0,
|
||
.len = sizeof(ctrl_byte),
|
||
.buf = &ctrl_byte,
|
||
};
|
||
|
||
status = i2c_transfer(client->adapter, &msg, 1);
|
||
if (status < 0)
|
||
return status;
|
||
if (status != 1)
|
||
return -EIO;
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int max127_read_channel(struct i2c_client *client, long *val)
|
||
{
|
||
int status;
|
||
u8 i2c_data[MAX127_DATA_LEN];
|
||
struct i2c_msg msg = {
|
||
.addr = client->addr,
|
||
.flags = I2C_M_RD,
|
||
.len = sizeof(i2c_data),
|
||
.buf = i2c_data,
|
||
};
|
||
|
||
status = i2c_transfer(client->adapter, &msg, 1);
|
||
if (status < 0)
|
||
return status;
|
||
if (status != 1)
|
||
return -EIO;
|
||
|
||
*val = (i2c_data[1] >> MAX127_DATA_SHIFT) |
|
||
((u16)i2c_data[0] << MAX127_DATA_SHIFT);
|
||
return 0;
|
||
}
|
||
|
||
static long max127_process_raw(u8 ctrl_byte, long raw)
|
||
{
|
||
long scale, weight;
|
||
|
||
/*
|
||
* MAX127's data coding is binary in unipolar mode with 1 LSB =
|
||
* (Full-Scale/4096) and two’s complement binary in bipolar mode
|
||
* with 1 LSB = [(2 x |FS|)/4096].
|
||
* Refer to MAX127 datasheet, "Transfer Function" section for
|
||
* details.
|
||
*/
|
||
scale = (ctrl_byte & MAX127_CTRL_RNG) ? MAX127_FULL_RANGE :
|
||
MAX127_HALF_RANGE;
|
||
if (ctrl_byte & MAX127_CTRL_BIP) {
|
||
weight = (raw & MAX127_SIGN_BIT);
|
||
raw &= ~MAX127_SIGN_BIT;
|
||
raw -= weight;
|
||
raw *= 2;
|
||
}
|
||
|
||
return raw * scale / 4096;
|
||
}
|
||
|
||
static int max127_read_input(struct max127_data *data, int channel, long *val)
|
||
{
|
||
long raw;
|
||
int status;
|
||
struct i2c_client *client = data->client;
|
||
u8 ctrl_byte = data->ctrl_byte[channel];
|
||
|
||
mutex_lock(&data->lock);
|
||
|
||
status = max127_select_channel(client, ctrl_byte);
|
||
if (status)
|
||
goto exit;
|
||
|
||
status = max127_read_channel(client, &raw);
|
||
if (status)
|
||
goto exit;
|
||
|
||
*val = max127_process_raw(ctrl_byte, raw);
|
||
|
||
exit:
|
||
mutex_unlock(&data->lock);
|
||
return status;
|
||
}
|
||
|
||
static int max127_read_min(struct max127_data *data, int channel, long *val)
|
||
{
|
||
u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3;
|
||
static const int min_input_map[4] = {
|
||
0, /* RNG=0, BIP=0 */
|
||
-MAX127_HALF_RANGE, /* RNG=0, BIP=1 */
|
||
0, /* RNG=1, BIP=0 */
|
||
-MAX127_FULL_RANGE, /* RNG=1, BIP=1 */
|
||
};
|
||
|
||
*val = min_input_map[rng_bip];
|
||
return 0;
|
||
}
|
||
|
||
static int max127_read_max(struct max127_data *data, int channel, long *val)
|
||
{
|
||
u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3;
|
||
static const int max_input_map[4] = {
|
||
MAX127_HALF_RANGE, /* RNG=0, BIP=0 */
|
||
MAX127_HALF_RANGE, /* RNG=0, BIP=1 */
|
||
MAX127_FULL_RANGE, /* RNG=1, BIP=0 */
|
||
MAX127_FULL_RANGE, /* RNG=1, BIP=1 */
|
||
};
|
||
|
||
*val = max_input_map[rng_bip];
|
||
return 0;
|
||
}
|
||
|
||
static int max127_write_min(struct max127_data *data, int channel, long val)
|
||
{
|
||
u8 ctrl;
|
||
|
||
mutex_lock(&data->lock);
|
||
|
||
ctrl = data->ctrl_byte[channel];
|
||
if (val <= -MAX127_FULL_RANGE) {
|
||
ctrl |= (MAX127_CTRL_RNG | MAX127_CTRL_BIP);
|
||
} else if (val < 0) {
|
||
ctrl |= MAX127_CTRL_BIP;
|
||
ctrl &= ~MAX127_CTRL_RNG;
|
||
} else {
|
||
ctrl &= ~MAX127_CTRL_BIP;
|
||
}
|
||
data->ctrl_byte[channel] = ctrl;
|
||
|
||
mutex_unlock(&data->lock);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int max127_write_max(struct max127_data *data, int channel, long val)
|
||
{
|
||
mutex_lock(&data->lock);
|
||
|
||
if (val >= MAX127_FULL_RANGE)
|
||
data->ctrl_byte[channel] |= MAX127_CTRL_RNG;
|
||
else
|
||
data->ctrl_byte[channel] &= ~MAX127_CTRL_RNG;
|
||
|
||
mutex_unlock(&data->lock);
|
||
|
||
return 0;
|
||
}
|
||
|
||
static umode_t max127_is_visible(const void *_data,
|
||
enum hwmon_sensor_types type,
|
||
u32 attr, int channel)
|
||
{
|
||
if (type == hwmon_in) {
|
||
switch (attr) {
|
||
case hwmon_in_input:
|
||
return 0444;
|
||
|
||
case hwmon_in_min:
|
||
case hwmon_in_max:
|
||
return 0644;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
static int max127_read(struct device *dev, enum hwmon_sensor_types type,
|
||
u32 attr, int channel, long *val)
|
||
{
|
||
int status;
|
||
struct max127_data *data = dev_get_drvdata(dev);
|
||
|
||
if (type != hwmon_in)
|
||
return -EOPNOTSUPP;
|
||
|
||
switch (attr) {
|
||
case hwmon_in_input:
|
||
status = max127_read_input(data, channel, val);
|
||
break;
|
||
|
||
case hwmon_in_min:
|
||
status = max127_read_min(data, channel, val);
|
||
break;
|
||
|
||
case hwmon_in_max:
|
||
status = max127_read_max(data, channel, val);
|
||
break;
|
||
|
||
default:
|
||
status = -EOPNOTSUPP;
|
||
break;
|
||
}
|
||
|
||
return status;
|
||
}
|
||
|
||
static int max127_write(struct device *dev, enum hwmon_sensor_types type,
|
||
u32 attr, int channel, long val)
|
||
{
|
||
int status;
|
||
struct max127_data *data = dev_get_drvdata(dev);
|
||
|
||
if (type != hwmon_in)
|
||
return -EOPNOTSUPP;
|
||
|
||
switch (attr) {
|
||
case hwmon_in_min:
|
||
status = max127_write_min(data, channel, val);
|
||
break;
|
||
|
||
case hwmon_in_max:
|
||
status = max127_write_max(data, channel, val);
|
||
break;
|
||
|
||
default:
|
||
status = -EOPNOTSUPP;
|
||
break;
|
||
}
|
||
|
||
return status;
|
||
}
|
||
|
||
static const struct hwmon_ops max127_hwmon_ops = {
|
||
.is_visible = max127_is_visible,
|
||
.read = max127_read,
|
||
.write = max127_write,
|
||
};
|
||
|
||
static const struct hwmon_channel_info *max127_info[] = {
|
||
HWMON_CHANNEL_INFO(in,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX,
|
||
HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX),
|
||
NULL,
|
||
};
|
||
|
||
static const struct hwmon_chip_info max127_chip_info = {
|
||
.ops = &max127_hwmon_ops,
|
||
.info = max127_info,
|
||
};
|
||
|
||
static int max127_probe(struct i2c_client *client,
|
||
const struct i2c_device_id *id)
|
||
{
|
||
int i;
|
||
struct device *hwmon_dev;
|
||
struct max127_data *data;
|
||
struct device *dev = &client->dev;
|
||
|
||
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
|
||
if (!data)
|
||
return -ENOMEM;
|
||
|
||
data->client = client;
|
||
mutex_init(&data->lock);
|
||
for (i = 0; i < ARRAY_SIZE(data->ctrl_byte); i++)
|
||
data->ctrl_byte[i] = (MAX127_CTRL_START |
|
||
MAX127_SET_CHANNEL(i));
|
||
|
||
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
|
||
data,
|
||
&max127_chip_info,
|
||
NULL);
|
||
|
||
return PTR_ERR_OR_ZERO(hwmon_dev);
|
||
}
|
||
|
||
static const struct i2c_device_id max127_id[] = {
|
||
{ "max127", 0 },
|
||
{ }
|
||
};
|
||
MODULE_DEVICE_TABLE(i2c, max127_id);
|
||
|
||
static struct i2c_driver max127_driver = {
|
||
.class = I2C_CLASS_HWMON,
|
||
.driver = {
|
||
.name = "max127",
|
||
},
|
||
.probe = max127_probe,
|
||
.id_table = max127_id,
|
||
};
|
||
|
||
module_i2c_driver(max127_driver);
|
||
|
||
MODULE_LICENSE("GPL");
|
||
MODULE_AUTHOR("Mike Choi <mikechoi@fb.com>");
|
||
MODULE_AUTHOR("Tao Ren <rentao.bupt@gmail.com>");
|
||
MODULE_DESCRIPTION("MAX127 Hardware Monitoring driver");
|