hwmon: add MP5920 driver

Add support for MPS Hot-Swap controller mp5920. This driver exposes
telemetry and limit value readings and writings.

Signed-off-by: Alex Vdovydchenko <[e-mail]>
Reviewed-by: Thomas Weißschuh <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[groeck: Use min_t() to limit length of displayed model string]
Signed-off-by: Guenter Roeck <[e-mail]>

Documentation/hwmon/index.rst

···
    mp2975
    mp2993
    mp5023
+   mp5920
    mp5990
    mp9941
    mpq8785

Documentation/hwmon/mp5920.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp5920
+====================
+
+Supported chips:
+
+  * MPS MP5920
+
+    Prefix: 'mp5920'
+
+  * Datasheet
+
+    Publicly available at the MPS website : https://www.monolithicpower.com/en/mp5920.html
+
+Authors:
+
+	Tony Ao <[e-mail]>
+	Alex Vdovydchenko <[e-mail]>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP5920 Hot-Swap Controller.
+
+Device compliant with:
+
+- PMBus rev 1.3 interface.
+
+Device supports direct and linear format for reading input voltage,
+output voltage, output current, input power and temperature.
+
+The driver exports the following attributes via the 'sysfs' files
+for input voltage:
+
+**in1_input**
+
+**in1_label**
+
+**in1_rated_max**
+
+**in1_rated_min**
+
+**in1_crit**
+
+**in1_alarm**
+
+The driver provides the following attributes for output voltage:
+
+**in2_input**
+
+**in2_label**
+
+**in2_rated_max**
+
+**in2_rated_min**
+
+**in2_alarm**
+
+The driver provides the following attributes for output current:
+
+**curr1_input**
+
+**curr1_label**
+
+**curr1_crit**
+
+**curr1_alarm**
+
+**curr1_rated_max**
+
+The driver provides the following attributes for input power:
+
+**power1_input**
+
+**power1_label**
+
+**power1_max**
+
+**power1_rated_max**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_crit**
+
+**temp1_alarm**

drivers/hwmon/pmbus/Kconfig

···
 	  This driver can also be built as a module. If so, the module will
 	  be called mp5023.
 
+config SENSORS_MP5920
+	tristate "MPS MP5920"
+	help
+	  If you say yes here you get hardware monitoring support for Monolithic
+	  MP5920.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp5920.
+
 config SENSORS_MP5990
 	tristate "MPS MP5990"
 	help

drivers/hwmon/pmbus/Makefile

···
 obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_MP2993)	+= mp2993.o
 obj-$(CONFIG_SENSORS_MP5023)	+= mp5023.o
+obj-$(CONFIG_SENSORS_MP5920)	+= mp5920.o
 obj-$(CONFIG_SENSORS_MP5990)	+= mp5990.o
 obj-$(CONFIG_SENSORS_MP9941)	+= mp9941.o
 obj-$(CONFIG_SENSORS_MPQ7932)	+= mpq7932.o

drivers/hwmon/pmbus/mp5920.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MP5920 and compatible chips.
+ */
+
+#include <linux/i2c.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include "pmbus.h"
+
+static struct pmbus_driver_info mp5920_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] = 2266,
+	.b[PSC_VOLTAGE_IN] = 0,
+	.R[PSC_VOLTAGE_IN] = -1,
+	.m[PSC_VOLTAGE_OUT] = 2266,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = -1,
+	.m[PSC_CURRENT_OUT] = 546,
+	.b[PSC_CURRENT_OUT] = 0,
+	.R[PSC_CURRENT_OUT] = -2,
+	.m[PSC_POWER] = 5840,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = -3,
+	.m[PSC_TEMPERATURE] = 1067,
+	.b[PSC_TEMPERATURE] = 20500,
+	.R[PSC_TEMPERATURE] = -2,
+	.func[0] = PMBUS_HAVE_VIN  | PMBUS_HAVE_VOUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT |
+		PMBUS_HAVE_TEMP,
+};
+
+static int mp5920_probe(struct i2c_client *client)
+{
+	struct device *dev =  &client->dev;
+	int ret;
+	u8 buf[I2C_SMBUS_BLOCK_MAX];
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -ENODEV;
+
+	ret = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, buf);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to read PMBUS_MFR_MODEL\n");
+
+	if (ret != 6 || strncmp(buf, "MP5920", 6)) {
+		return dev_err_probe(dev, -ENODEV, "Model '%.*s' not supported\n",
+				     min_t(int, ret, sizeof(buf)), buf);
+	}
+
+	return pmbus_do_probe(client, &mp5920_info);
+}
+
+static const struct of_device_id mp5920_of_match[] = {
+	{ .compatible = "mps,mp5920" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, mp5920_of_match);
+
+static const struct i2c_device_id mp5920_id[] = {
+	{ "mp5920" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, mp5920_id);
+
+static struct i2c_driver mp5920_driver = {
+	.driver = {
+		.name = "mp5920",
+		.of_match_table = mp5920_of_match,
+	},
+	.probe = mp5920_probe,
+	.id_table = mp5920_id,
+};
+
+module_i2c_driver(mp5920_driver);
+
+MODULE_AUTHOR("Tony Ao <[e-mail]>");
+MODULE_AUTHOR("Alex Vdovydchenko <[e-mail]>");
+MODULE_DESCRIPTION("PMBus driver for MP5920 HSC");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(PMBUS);