hwmon: (pmbus) Add support for MPS Multi-phase mp5990

Add support for mp5990 device from Monolithic Power Systems, Inc. (MPS)
vendor. This is a Hot-Swap Controller.

Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Link: https://lore.kernel.org/r/20231113155008.2147090-3-peteryin.openbmc@gmail.com
[groeck: Improved and clarified comments]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -159,6 +159,7 @@ Hardware Monitoring Kernel Drivers
    mp2888
    mp2975
    mp5023
+   mp5990
    nct6683
    nct6775
    nct7802

Documentation/hwmon/mp5990.rst

@@ -0,0 +1,84 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp5990
+====================
+
+Supported chips:
+
+  * MPS MP5990
+
+    Prefix: 'mp5990'
+
+  * Datasheet
+
+    Publicly available at the MPS website : https://www.monolithicpower.com/en/mp5990.html
+
+Author:
+
+	Peter Yin <peteryin.openbmc@gmail.com>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP5990 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_max**
+
+**in1_max_alarm**
+
+**in1_min**
+
+**in1_min_alarm**
+
+The driver provides the following attributes for output voltage:
+
+**in2_input**
+
+**in2_label**
+
+**in2_alarm**
+
+The driver provides the following attributes for output current:
+
+**curr1_input**
+
+**curr1_label**
+
+**curr1_alarm**
+
+**curr1_max**
+
+The driver provides the following attributes for input power:
+
+**power1_input**
+
+**power1_label**
+
+**power1_alarm**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**
+
+**temp1_crit**
+
+**temp1_crit_alarm**

drivers/hwmon/pmbus/Kconfig

@@ -333,6 +333,15 @@ config SENSORS_MP5023
 	  This driver can also be built as a module. If so, the module will
 	  be called mp5023.
 
+config SENSORS_MP5990
+	tristate "MPS MP5990"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP5990.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp5990.
+
 config SENSORS_MPQ7932_REGULATOR
 	bool "Regulator support for MPQ7932"
 	depends on SENSORS_MPQ7932 && REGULATOR

drivers/hwmon/pmbus/Makefile

@@ -35,6 +35,7 @@ obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
 obj-$(CONFIG_SENSORS_MP2888)	+= mp2888.o
 obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_MP5023)	+= mp5023.o
+obj-$(CONFIG_SENSORS_MP5990)	+= mp5990.o
 obj-$(CONFIG_SENSORS_MPQ7932)	+= mpq7932.o
 obj-$(CONFIG_SENSORS_PLI1209BC)	+= pli1209bc.o
 obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o

drivers/hwmon/pmbus/mp5990.c

@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for MPS MP5990 Hot-Swap Controller
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include "pmbus.h"
+
+#define MP5990_EFUSE_CFG	(0xC4)
+#define MP5990_VOUT_FORMAT	BIT(9)
+
+struct mp5990_data {
+	struct pmbus_driver_info info;
+	u8 vout_mode;
+	u8 vout_linear_exponent;
+};
+
+#define to_mp5990_data(x)  container_of(x, struct mp5990_data, info)
+
+static int mp5990_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct mp5990_data *data = to_mp5990_data(info);
+
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		if (data->vout_mode == linear) {
+			/*
+			 * The VOUT format used by the chip is linear11,
+			 * not linear16. Report that VOUT is in linear mode
+			 * and return exponent value extracted while probing
+			 * the chip.
+			 */
+			return data->vout_linear_exponent;
+		}
+
+		/*
+		 * The datasheet does not support the VOUT command,
+		 * but the device responds with a default value of 0x17.
+		 * In the standard, 0x17 represents linear mode.
+		 * Therefore, we should report that VOUT is in direct
+		 * format when the chip is configured for it.
+		 */
+		return PB_VOUT_MODE_DIRECT;
+
+	default:
+		return -ENODATA;
+	}
+}
+
+static int mp5990_read_word_data(struct i2c_client *client, int page,
+				 int phase, int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct mp5990_data *data = to_mp5990_data(info);
+	int ret;
+	s32 mantissa;
+
+	switch (reg) {
+	case PMBUS_READ_VOUT:
+		ret = pmbus_read_word_data(client, page, phase, reg);
+		if (ret < 0)
+			return ret;
+		/*
+		 * Because the VOUT format used by the chip is linear11 and not
+		 * linear16, we disregard bits[15:11]. The exponent is reported
+		 * as part of the VOUT_MODE command.
+		 */
+		if (data->vout_mode == linear) {
+			mantissa = ((s16)((ret & 0x7ff) << 5)) >> 5;
+			ret = mantissa;
+		}
+		break;
+	default:
+		return -ENODATA;
+	}
+
+	return ret;
+}
+
+static struct pmbus_driver_info mp5990_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] = 0,
+	.m[PSC_VOLTAGE_OUT] = 32,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = 0,
+	.m[PSC_CURRENT_OUT] = 16,
+	.b[PSC_CURRENT_OUT] = 0,
+	.R[PSC_CURRENT_OUT] = 0,
+	.m[PSC_POWER] = 1,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = 0,
+	.m[PSC_TEMPERATURE] = 1,
+	.b[PSC_TEMPERATURE] = 0,
+	.R[PSC_TEMPERATURE] = 0,
+	.func[0] =
+		PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_PIN |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_IOUT |
+		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
+	.read_byte_data = mp5990_read_byte_data,
+	.read_word_data = mp5990_read_word_data,
+};
+
+static int mp5990_probe(struct i2c_client *client)
+{
+	struct pmbus_driver_info *info;
+	struct mp5990_data *data;
+	int ret;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct mp5990_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memcpy(&data->info, &mp5990_info, sizeof(*info));
+	info = &data->info;
+
+	/* Read Vout Config */
+	ret = i2c_smbus_read_word_data(client, MP5990_EFUSE_CFG);
+	if (ret < 0) {
+		dev_err(&client->dev, "Can't get vout mode.");
+		return ret;
+	}
+
+	/*
+	 * EFUSE_CFG (0xC4) bit9=1 is linear mode, bit=0 is direct mode.
+	 */
+	if (ret & MP5990_VOUT_FORMAT) {
+		data->vout_mode = linear;
+		data->info.format[PSC_VOLTAGE_IN] = linear;
+		data->info.format[PSC_VOLTAGE_OUT] = linear;
+		data->info.format[PSC_CURRENT_OUT] = linear;
+		data->info.format[PSC_POWER] = linear;
+		ret = i2c_smbus_read_word_data(client, PMBUS_READ_VOUT);
+		if (ret < 0) {
+			dev_err(&client->dev, "Can't get vout exponent.");
+			return ret;
+		}
+		data->vout_linear_exponent = (u8)((ret >> 11) & 0x1f);
+	} else {
+		data->vout_mode = direct;
+	}
+	return pmbus_do_probe(client, info);
+}
+
+static const struct of_device_id mp5990_of_match[] = {
+	{ .compatible = "mps,mp5990" },
+	{}
+};
+
+static const struct i2c_device_id mp5990_id[] = {
+	{"mp5990", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mp5990_id);
+
+static struct i2c_driver mp5990_driver = {
+	.driver = {
+		   .name = "mp5990",
+		   .of_match_table = mp5990_of_match,
+	},
+	.probe = mp5990_probe,
+	.id_table = mp5990_id,
+};
+module_i2c_driver(mp5990_driver);
+
+MODULE_AUTHOR("Peter Yin <peter.yin@quantatw.com>");
+MODULE_DESCRIPTION("PMBus driver for MP5990 HSC");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(PMBUS);