Commit cf583b42 authored by Andrew Jeffery's avatar Andrew Jeffery Committed by Guenter Roeck
Browse files

hwmon: (pmbus/max31785) Add dual tachometer support 



The dual tachometer feature is implemented in hardware with a TACHSEL
input to indicate the rotor under measurement, and exposed on the device
by extending the READ_FAN_SPEED_1 word with two extra bytes*. The need
to read the non-standard four-byte response leads to a cut-down
implementation of i2c_smbus_xfer_emulated() included in the driver.
Further, to expose the second rotor tachometer value to userspace the
values are exposed through virtual pages. We re-route accesses to
FAN_CONFIG_1_2 and READ_FAN_SPEED_1 on pages 23-28 (not defined by the
hardware) to the same registers on pages 0-5, and with the latter command
we extract the value from the second word of the four-byte response.

* The documentation recommends the slower rotor be associated with
TACHSEL=0, which corresponds to the first word of the response. The
TACHSEL=0 measurement is used by the controller's closed-loop fan
management to judge target fan rate.

Signed-off-by: default avatarAndrew Jeffery <andrew@aj.id.au>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 464df6fa

Documentation/hwmon/max31785

+5 −3
Original line number Diff line number Diff line
@@ -17,8 +17,9 @@ management with temperature and remote voltage sensing. Various fan control 
features are provided, including PWM frequency control, temperature hysteresis,

dual tachometer measurements, and fan health monitoring.



For dual rotor fan configuration, the MAX31785 exposes the slowest rotor of the

two in the fan[1-4]_input attributes.

For dual-rotor configurations the MAX31785A exposes the second rotor tachometer

readings in attributes fan[5-8]_input. By contrast the MAX31785 only exposes

the slowest rotor measurement, and does so in the fan[1-4]_input attributes.



Usage Notes

-----------
@@ -31,7 +32,8 @@ Sysfs attributes 


fan[1-4]_alarm		Fan alarm.

fan[1-4]_fault		Fan fault.

fan[1-4]_input		Fan RPM.

fan[1-8]_input		Fan RPM. On the MAX31785A, inputs 5-8 correspond to the

			second rotor of fans 1-4

fan[1-4]_target		Fan input target



in[1-6]_crit		Critical maximum output voltage

drivers/hwmon/pmbus/max31785.c

+147 −0
Original line number Diff line number Diff line
@@ -16,9 +16,79 @@ 


enum max31785_regs {

	MFR_REVISION		= 0x9b,

	MFR_FAN_CONFIG		= 0xf1,

};



#define MAX31785			0x3030

#define MAX31785A			0x3040



#define MFR_FAN_CONFIG_DUAL_TACH	BIT(12)



#define MAX31785_NR_PAGES		23

#define MAX31785_NR_FAN_PAGES		6



static int max31785_read_byte_data(struct i2c_client *client, int page,

				   int reg)

{

	if (page < MAX31785_NR_PAGES)

		return -ENODATA;



	switch (reg) {

	case PMBUS_VOUT_MODE:

		return -ENOTSUPP;

	case PMBUS_FAN_CONFIG_12:

		return pmbus_read_byte_data(client, page - MAX31785_NR_PAGES,

					    reg);

	}



	return -ENODATA;

}



static int max31785_write_byte(struct i2c_client *client, int page, u8 value)

{

	if (page < MAX31785_NR_PAGES)

		return -ENODATA;



	return -ENOTSUPP;

}



static int max31785_read_long_data(struct i2c_client *client, int page,

				   int reg, u32 *data)

{

	unsigned char cmdbuf[1];

	unsigned char rspbuf[4];

	int rc;



	struct i2c_msg msg[2] = {

		{

			.addr = client->addr,

			.flags = 0,

			.len = sizeof(cmdbuf),

			.buf = cmdbuf,

		},

		{

			.addr = client->addr,

			.flags = I2C_M_RD,

			.len = sizeof(rspbuf),

			.buf = rspbuf,

		},

	};



	cmdbuf[0] = reg;



	rc = pmbus_set_page(client, page);

	if (rc < 0)

		return rc;



	rc = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));

	if (rc < 0)

		return rc;



	*data = (rspbuf[0] << (0 * 8)) | (rspbuf[1] << (1 * 8)) |

		(rspbuf[2] << (2 * 8)) | (rspbuf[3] << (3 * 8));



	return rc;

}



static int max31785_get_pwm(struct i2c_client *client, int page)

{
@@ -62,9 +132,30 @@ static int max31785_get_pwm_mode(struct i2c_client *client, int page) 
static int max31785_read_word_data(struct i2c_client *client, int page,

				   int reg)

{

	u32 val;

	int rv;



	switch (reg) {

	case PMBUS_READ_FAN_SPEED_1:

		if (page < MAX31785_NR_PAGES)

			return -ENODATA;



		rv = max31785_read_long_data(client, page - MAX31785_NR_PAGES,

					     reg, &val);

		if (rv < 0)

			return rv;



		rv = (val >> 16) & 0xffff;

		break;

	case PMBUS_FAN_COMMAND_1:

		/*

		 * PMBUS_FAN_COMMAND_x is probed to judge whether or not to

		 * expose fan control registers.

		 *

		 * Don't expose fan_target attribute for virtual pages.

		 */

		rv = (page >= MAX31785_NR_PAGES) ? -ENOTSUPP : -ENODATA;

		break;

	case PMBUS_VIRT_PWM_1:

		rv = max31785_get_pwm(client, page);

		break;
@@ -157,11 +248,15 @@ static int max31785_write_word_data(struct i2c_client *client, int page, 
#define MAX31785_VOUT_FUNCS \

	(PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT)



#define MAX37185_NUM_FAN_PAGES 6



static const struct pmbus_driver_info max31785_info = {

	.pages = MAX31785_NR_PAGES,



	.write_word_data = max31785_write_word_data,

	.read_byte_data = max31785_read_byte_data,

	.read_word_data = max31785_read_word_data,

	.write_byte = max31785_write_byte,



	/* RPM */

	.format[PSC_FAN] = direct,
@@ -208,13 +303,46 @@ static const struct pmbus_driver_info max31785_info = { 
	.func[22] = MAX31785_VOUT_FUNCS,

};



static int max31785_configure_dual_tach(struct i2c_client *client,

					struct pmbus_driver_info *info)

{

	int ret;

	int i;



	for (i = 0; i < MAX31785_NR_FAN_PAGES; i++) {

		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);

		if (ret < 0)

			return ret;



		ret = i2c_smbus_read_word_data(client, MFR_FAN_CONFIG);

		if (ret < 0)

			return ret;



		if (ret & MFR_FAN_CONFIG_DUAL_TACH) {

			int virtual = MAX31785_NR_PAGES + i;



			info->pages = virtual + 1;

			info->func[virtual] |= PMBUS_HAVE_FAN12;

			info->func[virtual] |= PMBUS_PAGE_VIRTUAL;

		}

	}



	return 0;

}



static int max31785_probe(struct i2c_client *client,

			  const struct i2c_device_id *id)

{

	struct device *dev = &client->dev;

	struct pmbus_driver_info *info;

	bool dual_tach = false;

	s64 ret;



	if (!i2c_check_functionality(client->adapter,

				     I2C_FUNC_SMBUS_BYTE_DATA |

				     I2C_FUNC_SMBUS_WORD_DATA))

		return -ENODEV;



	info = devm_kzalloc(dev, sizeof(struct pmbus_driver_info), GFP_KERNEL);

	if (!info)

		return -ENOMEM;
@@ -225,6 +353,25 @@ static int max31785_probe(struct i2c_client *client, 
	if (ret < 0)

		return ret;



	ret = i2c_smbus_read_word_data(client, MFR_REVISION);

	if (ret < 0)

		return ret;



	if (ret == MAX31785A) {

		dual_tach = true;

	} else if (ret == MAX31785) {

		if (!strcmp("max31785a", id->name))

			dev_warn(dev, "Expected max3175a, found max31785: cannot provide secondary tachometer readings\n");

	} else {

		return -ENODEV;

	}



	if (dual_tach) {

		ret = max31785_configure_dual_tach(client, info);

		if (ret < 0)

			return ret;

	}



	return pmbus_do_probe(client, id, info);

}

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