hwmon: (pmbus/mpq7932) Add a support for mpq7932 Power Management IC

The MPQ7932 is a power management IC designed to operate from 5V buses to
power a variety of Advanced driver-assistance system SOCs. Six integrated
buck converters with hardware monitoring capability powers a variety of
target rails configurable over PMBus interface.

Signed-off-by: Saravanan Sekar <saravanan@linumiz.com>
Link: https://lore.kernel.org/r/20221207173716.123223-4-saravanan@linumiz.com
[groeck: Modified multi-line comments to match standard comment style]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/pmbus/Kconfig

@@ -317,6 +317,22 @@ config SENSORS_MP5023
 	  This driver can also be built as a module. If so, the module will
 	  be called mp5023.
 
+config SENSORS_MPQ7932_REGULATOR
+	bool "Regulator support for MPQ7932"
+	depends on SENSORS_MPQ7932 && REGULATOR
+	help
+	  If you say yes here you get six integrated buck converter regulator
+	  support for power management IC MPS MPQ7932.
+
+config SENSORS_MPQ7932
+	tristate "MPS MPQ7932"
+	help
+	  If you say yes here you get hardware monitoring functionality support
+	  for power management IC MPS MPQ7932.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mpq7932.
+
 config SENSORS_PIM4328
 	tristate "Flex PIM4328 and compatibles"
 	help

drivers/hwmon/pmbus/Makefile

@@ -34,6 +34,7 @@ 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-$(CONFIG_SENSORS_MPQ7932)	+= mpq7932.o
 obj-$(CONFIG_SENSORS_PLI1209BC)	+= pli1209bc.o
 obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o

drivers/hwmon/pmbus/mpq7932.c

@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * mpq7932.c - hwmon with optional regulator driver for mps mpq7932
+ * Copyright 2022 Monolithic Power Systems, Inc
+ *
+ * Author: Saravanan Sekar <saravanan@linumiz.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/pmbus.h>
+#include "pmbus.h"
+
+#define MPQ7932_BUCK_UV_MIN		206250
+#define MPQ7932_UV_STEP			6250
+#define MPQ7932_N_VOLTAGES		256
+#define MPQ7932_VOUT_MAX		0xFF
+#define MPQ7932_NUM_PAGES		6
+
+#define MPQ7932_TON_DELAY		0x60
+#define MPQ7932_VOUT_STARTUP_SLEW	0xA3
+#define MPQ7932_VOUT_SHUTDOWN_SLEW	0xA5
+#define MPQ7932_VOUT_SLEW_MASK		GENMASK(1, 0)
+#define MPQ7932_TON_DELAY_MASK		GENMASK(4, 0)
+
+struct mpq7932_data {
+	struct pmbus_driver_info info;
+	struct pmbus_platform_data pdata;
+};
+
+#if IS_ENABLED(CONFIG_SENSORS_MPQ7932_REGULATOR)
+static struct regulator_desc mpq7932_regulators_desc[] = {
+	PMBUS_REGULATOR_STEP("buck", 0, MPQ7932_N_VOLTAGES,
+			     MPQ7932_UV_STEP, MPQ7932_BUCK_UV_MIN),
+	PMBUS_REGULATOR_STEP("buck", 1, MPQ7932_N_VOLTAGES,
+			     MPQ7932_UV_STEP, MPQ7932_BUCK_UV_MIN),
+	PMBUS_REGULATOR_STEP("buck", 2, MPQ7932_N_VOLTAGES,
+			     MPQ7932_UV_STEP, MPQ7932_BUCK_UV_MIN),
+	PMBUS_REGULATOR_STEP("buck", 3, MPQ7932_N_VOLTAGES,
+			     MPQ7932_UV_STEP, MPQ7932_BUCK_UV_MIN),
+	PMBUS_REGULATOR_STEP("buck", 4, MPQ7932_N_VOLTAGES,
+			     MPQ7932_UV_STEP, MPQ7932_BUCK_UV_MIN),
+	PMBUS_REGULATOR_STEP("buck", 5, MPQ7932_N_VOLTAGES,
+			     MPQ7932_UV_STEP, MPQ7932_BUCK_UV_MIN),
+};
+#endif
+
+static int mpq7932_write_word_data(struct i2c_client *client, int page, int reg,
+				   u16 word)
+{
+	switch (reg) {
+	/*
+	 * chip supports only byte access for VOUT_COMMAND otherwise
+	 * access results -EREMOTEIO
+	 */
+	case PMBUS_VOUT_COMMAND:
+		return pmbus_write_byte_data(client, page, reg, word & 0xFF);
+
+	default:
+		return -ENODATA;
+	}
+}
+
+static int mpq7932_read_word_data(struct i2c_client *client, int page,
+				  int phase, int reg)
+{
+	switch (reg) {
+	/*
+	 * chip supports neither (PMBUS_VOUT_MARGIN_HIGH, PMBUS_VOUT_MARGIN_LOW)
+	 * nor (PMBUS_MFR_VOUT_MIN, PMBUS_MFR_VOUT_MAX). As a result set voltage
+	 * fails due to error in pmbus_regulator_get_low_margin, so faked.
+	 */
+	case PMBUS_MFR_VOUT_MIN:
+		return 0;
+
+	case PMBUS_MFR_VOUT_MAX:
+		return MPQ7932_VOUT_MAX;
+
+	/*
+	 * chip supports only byte access for VOUT_COMMAND otherwise
+	 * access results in -EREMOTEIO
+	 */
+	case PMBUS_READ_VOUT:
+		return pmbus_read_byte_data(client, page, PMBUS_VOUT_COMMAND);
+
+	default:
+		return -ENODATA;
+	}
+}
+
+static int mpq7932_probe(struct i2c_client *client)
+{
+	struct mpq7932_data *data;
+	struct pmbus_driver_info *info;
+	struct device *dev = &client->dev;
+	int i;
+
+	data = devm_kzalloc(dev, sizeof(struct mpq7932_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	info = &data->info;
+	info->pages = MPQ7932_NUM_PAGES;
+	info->format[PSC_VOLTAGE_OUT] = direct;
+	info->m[PSC_VOLTAGE_OUT] = 160;
+	info->b[PSC_VOLTAGE_OUT] = -33;
+	for (i = 0; i < info->pages; i++) {
+		info->func[i] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
+				| PMBUS_HAVE_STATUS_TEMP;
+	}
+
+#if IS_ENABLED(CONFIG_SENSORS_MPQ7932_REGULATOR)
+	info->num_regulators = ARRAY_SIZE(mpq7932_regulators_desc);
+	info->reg_desc = mpq7932_regulators_desc;
+#endif
+
+	info->read_word_data = mpq7932_read_word_data;
+	info->write_word_data = mpq7932_write_word_data;
+
+	data->pdata.flags = PMBUS_NO_CAPABILITY;
+	dev->platform_data = &data->pdata;
+
+	return pmbus_do_probe(client, info);
+}
+
+static const struct of_device_id mpq7932_of_match[] = {
+	{ .compatible = "mps,mpq7932"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, mpq7932_of_match);
+
+static const struct i2c_device_id mpq7932_id[] = {
+	{ "mpq7932", },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, mpq7932_id);
+
+static struct i2c_driver mpq7932_regulator_driver = {
+	.driver = {
+		.name = "mpq7932",
+		.of_match_table = mpq7932_of_match,
+	},
+	.probe_new = mpq7932_probe,
+	.id_table = mpq7932_id,
+};
+module_i2c_driver(mpq7932_regulator_driver);
+
+MODULE_AUTHOR("Saravanan Sekar <saravanan@linumiz.com>");
+MODULE_DESCRIPTION("MPQ7932 PMIC regulator driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(PMBUS);