Andrew Jeffery 56ad86b4b1 hwmon: (pmbus/max31785) Add fan control
The implementation makes use of the new fan control virtual registers
exposed by the pmbus core. It mixes use of the default implementations
with some overrides via the read/write handlers to handle FAN_COMMAND_1
on the MAX31785, whose definition breaks the value range into various
control bands dependent on RPM or PWM mode.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2018-01-02 15:05:34 -08:00

253 lines
5.9 KiB
C

/*
* Copyright (C) 2017 IBM Corp.
*
* 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/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include "pmbus.h"
enum max31785_regs {
MFR_REVISION = 0x9b,
};
#define MAX31785_NR_PAGES 23
static int max31785_get_pwm(struct i2c_client *client, int page)
{
int rv;
rv = pmbus_get_fan_rate_device(client, page, 0, percent);
if (rv < 0)
return rv;
else if (rv >= 0x8000)
return 0;
else if (rv >= 0x2711)
return 0x2710;
return rv;
}
static int max31785_get_pwm_mode(struct i2c_client *client, int page)
{
int config;
int command;
config = pmbus_read_byte_data(client, page, PMBUS_FAN_CONFIG_12);
if (config < 0)
return config;
command = pmbus_read_word_data(client, page, PMBUS_FAN_COMMAND_1);
if (command < 0)
return command;
if (config & PB_FAN_1_RPM)
return (command >= 0x8000) ? 3 : 2;
if (command >= 0x8000)
return 3;
else if (command >= 0x2711)
return 0;
return 1;
}
static int max31785_read_word_data(struct i2c_client *client, int page,
int reg)
{
int rv;
switch (reg) {
case PMBUS_VIRT_PWM_1:
rv = max31785_get_pwm(client, page);
break;
case PMBUS_VIRT_PWM_ENABLE_1:
rv = max31785_get_pwm_mode(client, page);
break;
default:
rv = -ENODATA;
break;
}
return rv;
}
static inline u32 max31785_scale_pwm(u32 sensor_val)
{
/*
* The datasheet describes the accepted value range for manual PWM as
* [0, 0x2710], while the hwmon pwmX sysfs interface accepts values in
* [0, 255]. The MAX31785 uses DIRECT mode to scale the FAN_COMMAND
* registers and in PWM mode the coefficients are m=1, b=0, R=2. The
* important observation here is that 0x2710 == 10000 == 100 * 100.
*
* R=2 (== 10^2 == 100) accounts for scaling the value provided at the
* sysfs interface into the required hardware resolution, but it does
* not yet yield a value that we can write to the device (this initial
* scaling is handled by pmbus_data2reg()). Multiplying by 100 below
* translates the parameter value into the percentage units required by
* PMBus, and then we scale back by 255 as required by the hwmon pwmX
* interface to yield the percentage value at the appropriate
* resolution for hardware.
*/
return (sensor_val * 100) / 255;
}
static int max31785_pwm_enable(struct i2c_client *client, int page,
u16 word)
{
int config = 0;
int rate;
switch (word) {
case 0:
rate = 0x7fff;
break;
case 1:
rate = pmbus_get_fan_rate_cached(client, page, 0, percent);
if (rate < 0)
return rate;
rate = max31785_scale_pwm(rate);
break;
case 2:
config = PB_FAN_1_RPM;
rate = pmbus_get_fan_rate_cached(client, page, 0, rpm);
if (rate < 0)
return rate;
break;
case 3:
rate = 0xffff;
break;
default:
return -EINVAL;
}
return pmbus_update_fan(client, page, 0, config, PB_FAN_1_RPM, rate);
}
static int max31785_write_word_data(struct i2c_client *client, int page,
int reg, u16 word)
{
switch (reg) {
case PMBUS_VIRT_PWM_1:
return pmbus_update_fan(client, page, 0, 0, PB_FAN_1_RPM,
max31785_scale_pwm(word));
case PMBUS_VIRT_PWM_ENABLE_1:
return max31785_pwm_enable(client, page, word);
default:
break;
}
return -ENODATA;
}
#define MAX31785_FAN_FUNCS \
(PMBUS_HAVE_FAN12 | PMBUS_HAVE_STATUS_FAN12 | PMBUS_HAVE_PWM12)
#define MAX31785_TEMP_FUNCS \
(PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP)
#define MAX31785_VOUT_FUNCS \
(PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT)
static const struct pmbus_driver_info max31785_info = {
.pages = MAX31785_NR_PAGES,
.write_word_data = max31785_write_word_data,
.read_word_data = max31785_read_word_data,
/* RPM */
.format[PSC_FAN] = direct,
.m[PSC_FAN] = 1,
.b[PSC_FAN] = 0,
.R[PSC_FAN] = 0,
/* PWM */
.format[PSC_PWM] = direct,
.m[PSC_PWM] = 1,
.b[PSC_PWM] = 0,
.R[PSC_PWM] = 2,
.func[0] = MAX31785_FAN_FUNCS,
.func[1] = MAX31785_FAN_FUNCS,
.func[2] = MAX31785_FAN_FUNCS,
.func[3] = MAX31785_FAN_FUNCS,
.func[4] = MAX31785_FAN_FUNCS,
.func[5] = MAX31785_FAN_FUNCS,
.format[PSC_TEMPERATURE] = direct,
.m[PSC_TEMPERATURE] = 1,
.b[PSC_TEMPERATURE] = 0,
.R[PSC_TEMPERATURE] = 2,
.func[6] = MAX31785_TEMP_FUNCS,
.func[7] = MAX31785_TEMP_FUNCS,
.func[8] = MAX31785_TEMP_FUNCS,
.func[9] = MAX31785_TEMP_FUNCS,
.func[10] = MAX31785_TEMP_FUNCS,
.func[11] = MAX31785_TEMP_FUNCS,
.func[12] = MAX31785_TEMP_FUNCS,
.func[13] = MAX31785_TEMP_FUNCS,
.func[14] = MAX31785_TEMP_FUNCS,
.func[15] = MAX31785_TEMP_FUNCS,
.func[16] = MAX31785_TEMP_FUNCS,
.format[PSC_VOLTAGE_OUT] = direct,
.m[PSC_VOLTAGE_OUT] = 1,
.b[PSC_VOLTAGE_OUT] = 0,
.R[PSC_VOLTAGE_OUT] = 0,
.func[17] = MAX31785_VOUT_FUNCS,
.func[18] = MAX31785_VOUT_FUNCS,
.func[19] = MAX31785_VOUT_FUNCS,
.func[20] = MAX31785_VOUT_FUNCS,
.func[21] = MAX31785_VOUT_FUNCS,
.func[22] = MAX31785_VOUT_FUNCS,
};
static int max31785_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct pmbus_driver_info *info;
s64 ret;
info = devm_kzalloc(dev, sizeof(struct pmbus_driver_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
*info = max31785_info;
ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 255);
if (ret < 0)
return ret;
return pmbus_do_probe(client, id, info);
}
static const struct i2c_device_id max31785_id[] = {
{ "max31785", 0 },
{ "max31785a", 0 },
{ },
};
MODULE_DEVICE_TABLE(i2c, max31785_id);
static struct i2c_driver max31785_driver = {
.driver = {
.name = "max31785",
},
.probe = max31785_probe,
.remove = pmbus_do_remove,
.id_table = max31785_id,
};
module_i2c_driver(max31785_driver);
MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
MODULE_DESCRIPTION("PMBus driver for the Maxim MAX31785");
MODULE_LICENSE("GPL");