Commit 0c459759 authored by Delphine CC Chiu's avatar Delphine CC Chiu Committed by Guenter Roeck
Browse files

hwmon: (pmbus) Add ltc4286 driver 



Add a driver to support ltc4286 chip

Signed-off-by: default avatarDelphine CC Chiu <Delphine_CC_Chiu@Wiwynn.com>
Link: https://lore.kernel.org/r/20231123015440.199822-3-Delphine_CC_Chiu@Wiwynn.com


[groeck: Fixed formatting]
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 7707cf82

Documentation/hwmon/index.rst

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@@ -128,6 +128,7 @@ Hardware Monitoring Kernel Drivers 
   ltc4245

   ltc4260

   ltc4261

   ltc4286

   max127

   max15301

   max16064

Documentation/hwmon/ltc4286.rst

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.. SPDX-License-Identifier: GPL-2.0-or-later



Kernel driver ltc4286

=====================



Supported chips:



  * Analog Devices LTC4286



    Prefix: 'ltc4286'



    Addresses scanned: -



    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4286.pdf



  * Analog Devices LTC4287



    Prefix: 'ltc4287'



    Addresses scanned: -



    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4287.pdf



Author: Delphine CC Chiu <Delphine_CC_Chiu@Wiwynn.com>





Description

-----------



This driver supports hardware monitoring for Analog Devices LTC4286

and LTC4287 Hot-Swap Controller and Digital Power Monitors.



LTC4286 and LTC4287 are hot-swap controllers that allow a circuit board

to be removed from or inserted into a live backplane. They also feature

current and voltage readback via an integrated 12 bit analog-to-digital

converter (ADC), accessed using a PMBus interface.



The driver is a client driver to the core PMBus driver. Please see

Documentation/hwmon/pmbus.rst for details on PMBus client drivers.





Usage Notes

-----------



This driver does not auto-detect devices. You will have to instantiate the

devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for

details.



The shunt value in micro-ohms can be set via device tree at compile-time. Please

refer to the Documentation/devicetree/bindings/hwmon/lltc,ltc4286.yaml for bindings

if the device tree is used.





Platform data support

---------------------



The driver supports standard PMBus driver platform data. Please see

Documentation/hwmon/pmbus.rst for details.





Sysfs entries

-------------



The following attributes are supported. Limits are read-write, history reset

attributes are write-only, all other attributes are read-only.



======================= =======================================================

in1_label		"vin"

in1_input		Measured voltage.

in1_alarm		Input voltage alarm.

in1_min 		Minimum input voltage.

in1_max 		Maximum input voltage.



in2_label		"vout1"

in2_input		Measured voltage.

in2_alarm		Output voltage alarm.

in2_min 		Minimum output voltage.

in2_max 		Maximum output voltage.



curr1_label		"iout1"

curr1_input		Measured current.

curr1_alarm		Output current alarm.

curr1_max		Maximum current.



power1_label		"pin"

power1_input		Input power.

power1_alarm		Input power alarm.

power1_max		Maximum poewr.



temp1_input		Chip temperature.

temp1_min		Minimum chip temperature.

temp1_max		Maximum chip temperature.

temp1_crit		Critical chip temperature.

temp1_alarm		Chip temperature alarm.

======================= =======================================================

drivers/hwmon/pmbus/Kconfig

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@@ -227,6 +227,16 @@ config SENSORS_LTC3815 
	  This driver can also be built as a module. If so, the module will

	  be called ltc3815.



config SENSORS_LTC4286

	bool "Analog Devices LTC4286"

	help

	  LTC4286 is an integrated solution for hot swap applications that

	  allows a board to be safely inserted and removed from a live

	  backplane.

	  This chip could be used to monitor voltage, current, ...etc.

	  If you say yes here you get hardware monitoring support for Analog

	  Devices LTC4286.



config SENSORS_MAX15301

	tristate "Maxim MAX15301"

	help

drivers/hwmon/pmbus/Makefile

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@@ -24,6 +24,7 @@ obj-$(CONFIG_SENSORS_LM25066) += lm25066.o 
obj-$(CONFIG_SENSORS_LT7182S)	+= lt7182s.o

obj-$(CONFIG_SENSORS_LTC2978)	+= ltc2978.o

obj-$(CONFIG_SENSORS_LTC3815)	+= ltc3815.o

obj-$(CONFIG_SENSORS_LTC4286)	+= ltc4286.o

obj-$(CONFIG_SENSORS_MAX15301)	+= max15301.o

obj-$(CONFIG_SENSORS_MAX16064)	+= max16064.o

obj-$(CONFIG_SENSORS_MAX16601)	+= max16601.o

drivers/hwmon/pmbus/ltc4286.c

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// SPDX-License-Identifier: GPL-2.0-or-later



#include <linux/err.h>

#include <linux/i2c.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/pmbus.h>

#include "pmbus.h"



/* LTC4286 register */

#define LTC4286_MFR_CONFIG1	0xF2



/* LTC4286 configuration */

#define VRANGE_SELECT_BIT	BIT(1)



#define LTC4286_MFR_ID_SIZE	3



/*

 * Initialize the MBR as default settings which is referred to LTC4286 datasheet

 * (March 22, 2022 version) table 3 page 16

 */

static struct pmbus_driver_info ltc4286_info = {

	.pages = 1,

	.format[PSC_VOLTAGE_IN] = direct,

	.format[PSC_VOLTAGE_OUT] = direct,

	.format[PSC_CURRENT_OUT] = direct,

	.format[PSC_POWER] = direct,

	.format[PSC_TEMPERATURE] = direct,

	.m[PSC_VOLTAGE_IN] = 32,

	.b[PSC_VOLTAGE_IN] = 0,

	.R[PSC_VOLTAGE_IN] = 1,

	.m[PSC_VOLTAGE_OUT] = 32,

	.b[PSC_VOLTAGE_OUT] = 0,

	.R[PSC_VOLTAGE_OUT] = 1,

	.m[PSC_CURRENT_OUT] = 1024,

	.b[PSC_CURRENT_OUT] = 0,

	/*

	 * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.

	 * However, the rsense value that user input is micro ohm.

	 * Thus, the MBR setting which involves rsense should be shifted by 6 digits.

	 */

	.R[PSC_CURRENT_OUT] = 3 - 6,

	.m[PSC_POWER] = 1,

	.b[PSC_POWER] = 0,

	/*

	 * The rsense value used in MBR formula in LTC4286 datasheet should be ohm unit.

	 * However, the rsense value that user input is micro ohm.

	 * Thus, the MBR setting which involves rsense should be shifted by 6 digits.

	 */

	.R[PSC_POWER] = 4 - 6,

	.m[PSC_TEMPERATURE] = 1,

	.b[PSC_TEMPERATURE] = 273,

	.R[PSC_TEMPERATURE] = 0,

	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |

		   PMBUS_HAVE_PIN | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_VOUT |

		   PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_STATUS_TEMP,

};



static const struct i2c_device_id ltc4286_id[] = {

	{ "ltc4286", 0 },

	{ "ltc4287", 1 },

	{}

};

MODULE_DEVICE_TABLE(i2c, ltc4286_id);



static int ltc4286_probe(struct i2c_client *client)

{

	int ret;

	const struct i2c_device_id *mid;

	u8 block_buffer[I2C_SMBUS_BLOCK_MAX + 1];

	struct pmbus_driver_info *info;

	u32 rsense;

	int vrange_nval, vrange_oval;



	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, block_buffer);

	if (ret < 0) {

		return dev_err_probe(&client->dev, ret,

				     "Failed to read manufacturer id\n");

	}



	/*

	 * Refer to ltc4286 datasheet page 20

	 * the manufacturer id is LTC

	 */

	if (ret != LTC4286_MFR_ID_SIZE ||

	    strncmp(block_buffer, "LTC", LTC4286_MFR_ID_SIZE)) {

		return dev_err_probe(&client->dev, -ENODEV,

				     "Manufacturer id mismatch\n");

	}



	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, block_buffer);

	if (ret < 0) {

		return dev_err_probe(&client->dev, ret,

				     "Failed to read manufacturer model\n");

	}



	for (mid = ltc4286_id; mid->name[0]; mid++) {

		if (!strncasecmp(mid->name, block_buffer, strlen(mid->name)))

			break;

	}

	if (!mid->name[0])

		return dev_err_probe(&client->dev, -ENODEV,

				     "Unsupported device\n");



	if (of_property_read_u32(client->dev.of_node,

				 "shunt-resistor-micro-ohms", &rsense))

		rsense = 300; /* 0.3 mOhm if not set via DT */



	if (rsense == 0)

		return -EINVAL;



	/* Check for the latter MBR value won't overflow */

	if (rsense > (INT_MAX / 1024))

		return -EINVAL;



	info = devm_kmemdup(&client->dev, &ltc4286_info, sizeof(*info),

			    GFP_KERNEL);

	if (!info)

		return -ENOMEM;



	/* Check MFR1 CONFIG register bit 1 VRANGE_SELECT before driver loading */

	vrange_oval = i2c_smbus_read_word_data(client, LTC4286_MFR_CONFIG1);

	if (vrange_oval < 0)

		return dev_err_probe(&client->dev, vrange_oval,

				     "Failed to read manufacturer configuration one\n");

	vrange_nval = vrange_oval;



	if (device_property_read_bool(&client->dev, "adi,vrange-low-enable")) {

		vrange_nval &=

			~VRANGE_SELECT_BIT; /* VRANGE_SELECT = 0, 25.6 volts */



		info->m[PSC_VOLTAGE_IN] = 128;

		info->m[PSC_VOLTAGE_OUT] = 128;

		info->m[PSC_POWER] = 4 * rsense;

	} else {

		vrange_nval |=

			VRANGE_SELECT_BIT; /* VRANGE_SELECT = 1, 102.4 volts */



		info->m[PSC_POWER] = rsense;

	}

	if (vrange_nval != vrange_oval) {

		/* Set MFR1 CONFIG register bit 1 VRANGE_SELECT */

		ret = i2c_smbus_write_word_data(client, LTC4286_MFR_CONFIG1,

						vrange_nval);

		if (ret < 0)

			return dev_err_probe(&client->dev, ret,

					     "Failed to set vrange\n");

	}



	info->m[PSC_CURRENT_OUT] = 1024 * rsense;



	return pmbus_do_probe(client, info);

}



static const struct of_device_id ltc4286_of_match[] = {

	{ .compatible = "lltc,ltc4286" },

	{ .compatible = "lltc,ltc4287" },

	{}

};



static struct i2c_driver ltc4286_driver = {

	.driver = {

		.name = "ltc4286",

		.of_match_table = ltc4286_of_match,

	},

	.probe = ltc4286_probe,

	.id_table = ltc4286_id,

};



module_i2c_driver(ltc4286_driver);



MODULE_AUTHOR("Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>");

MODULE_DESCRIPTION("PMBUS driver for LTC4286 and compatibles");

MODULE_LICENSE("GPL");