hwmon: (pmbus) Driver for Maxim MAX16601

MAX16601 is a VR13.HC Dual-Output Voltage Regulator Chipset,
implementing a (8+1) multiphase synchronous buck converter.

Cc: Alex Qiu <xqiu@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

3 files changed, 324 insertions, 0 deletions

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index de12a565006d..a337195b1c39 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -146,6 +146,15 @@ config SENSORS_MAX16064
 	  This driver can also be built as a module. If so, the module will
 	  be called max16064.
 
+config SENSORS_MAX16601
+	tristate "Maxim MAX16601"
+	help
+	  If you say yes here you get hardware monitoring support for Maxim
+	  MAX16601.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called max16601.
+
 config SENSORS_MAX20730
 	tristate "Maxim MAX20730, MAX20734, MAX20743"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 5feb45806123..c4b15db996ad 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_SENSORS_LM25066)	+= lm25066.o
 obj-$(CONFIG_SENSORS_LTC2978)	+= ltc2978.o
 obj-$(CONFIG_SENSORS_LTC3815)	+= ltc3815.o
 obj-$(CONFIG_SENSORS_MAX16064)	+= max16064.o
+obj-$(CONFIG_SENSORS_MAX16601)	+= max16601.o
 obj-$(CONFIG_SENSORS_MAX20730)	+= max20730.o
 obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
 obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
diff --git a/drivers/hwmon/pmbus/max16601.c b/drivers/hwmon/pmbus/max16601.c
new file mode 100644
index 000000000000..51cdfaf9023c
--- /dev/null
+++ b/drivers/hwmon/pmbus/max16601.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hardware monitoring driver for Maxim MAX16601
+ *
+ * Implementation notes:
+ *
+ * Ths chip supports two rails, VCORE and VSA. Telemetry information for the
+ * two rails is reported in two subsequent I2C addresses. The driver
+ * instantiates a dummy I2C client at the second I2C address to report
+ * information for the VSA rail in a single instance of the driver.
+ * Telemetry for the VSA rail is reported to the PMBus core in PMBus page 2.
+ *
+ * The chip reports input current using two separate methods. The input current
+ * reported with the standard READ_IIN command is derived from the output
+ * current. The first method is reported to the PMBus core with PMBus page 0,
+ * the second method is reported with PMBus page 1.
+ *
+ * The chip supports reading per-phase temperatures and per-phase input/output
+ * currents for VCORE. Telemetry is reported in vendor specific registers.
+ * The driver translates the vendor specific register values to PMBus standard
+ * register values and reports per-phase information in PMBus page 0.
+ *
+ * Copyright 2019, 2020 Google LLC.
+ */
+
+#include <linux/bits.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "pmbus.h"
+
+#define REG_SETPT_DVID		0xd1
+#define  DAC_10MV_MODE		BIT(4)
+#define REG_IOUT_AVG_PK		0xee
+#define REG_IIN_SENSOR		0xf1
+#define REG_TOTAL_INPUT_POWER	0xf2
+#define REG_PHASE_ID		0xf3
+#define  CORE_RAIL_INDICATOR	BIT(7)
+#define REG_PHASE_REPORTING	0xf4
+
+struct max16601_data {
+	struct pmbus_driver_info info;
+	struct i2c_client *vsa;
+	int iout_avg_pkg;
+};
+
+#define to_max16601_data(x) container_of(x, struct max16601_data, info)
+
+static int max16601_read_byte(struct i2c_client *client, int page, int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct max16601_data *data = to_max16601_data(info);
+
+	if (page > 0) {
+		if (page == 2)	/* VSA */
+			return i2c_smbus_read_byte_data(data->vsa, reg);
+		return -EOPNOTSUPP;
+	}
+	return -ENODATA;
+}
+
+static int max16601_read_word(struct i2c_client *client, int page, int phase,
+			      int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct max16601_data *data = to_max16601_data(info);
+	u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
+	int ret;
+
+	switch (page) {
+	case 0:		/* VCORE */
+		if (phase == 0xff)
+			return -ENODATA;
+		switch (reg) {
+		case PMBUS_READ_IIN:
+		case PMBUS_READ_IOUT:
+		case PMBUS_READ_TEMPERATURE_1:
+			ret = i2c_smbus_write_byte_data(client, REG_PHASE_ID,
+							phase);
+			if (ret)
+				return ret;
+			ret = i2c_smbus_read_block_data(client,
+							REG_PHASE_REPORTING,
+							buf);
+			if (ret < 0)
+				return ret;
+			if (ret < 6)
+				return -EIO;
+			switch (reg) {
+			case PMBUS_READ_TEMPERATURE_1:
+				return buf[1] << 8 | buf[0];
+			case PMBUS_READ_IOUT:
+				return buf[3] << 8 | buf[2];
+			case PMBUS_READ_IIN:
+				return buf[5] << 8 | buf[4];
+			default:
+				break;
+			}
+		}
+		return -EOPNOTSUPP;
+	case 1:		/* VCORE, read IIN/PIN from sensor element */
+		switch (reg) {
+		case PMBUS_READ_IIN:
+			return i2c_smbus_read_word_data(client, REG_IIN_SENSOR);
+		case PMBUS_READ_PIN:
+			return i2c_smbus_read_word_data(client,
+							REG_TOTAL_INPUT_POWER);
+		default:
+			break;
+		}
+		return -EOPNOTSUPP;
+	case 2:		/* VSA */
+		switch (reg) {
+		case PMBUS_VIRT_READ_IOUT_MAX:
+			ret = i2c_smbus_read_word_data(data->vsa,
+						       REG_IOUT_AVG_PK);
+			if (ret < 0)
+				return ret;
+			if (sign_extend32(ret, 10) >
+			    sign_extend32(data->iout_avg_pkg, 10))
+				data->iout_avg_pkg = ret;
+			return data->iout_avg_pkg;
+		case PMBUS_VIRT_RESET_IOUT_HISTORY:
+			return 0;
+		case PMBUS_IOUT_OC_FAULT_LIMIT:
+		case PMBUS_IOUT_OC_WARN_LIMIT:
+		case PMBUS_OT_FAULT_LIMIT:
+		case PMBUS_OT_WARN_LIMIT:
+		case PMBUS_READ_IIN:
+		case PMBUS_READ_IOUT:
+		case PMBUS_READ_TEMPERATURE_1:
+		case PMBUS_STATUS_WORD:
+			return i2c_smbus_read_word_data(data->vsa, reg);
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int max16601_write_byte(struct i2c_client *client, int page, u8 reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct max16601_data *data = to_max16601_data(info);
+
+	if (page == 2) {
+		if (reg == PMBUS_CLEAR_FAULTS)
+			return i2c_smbus_write_byte(data->vsa, reg);
+		return -EOPNOTSUPP;
+	}
+	return -ENODATA;
+}
+
+static int max16601_write_word(struct i2c_client *client, int page, int reg,
+			       u16 value)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct max16601_data *data = to_max16601_data(info);
+
+	switch (page) {
+	case 0:		/* VCORE */
+		return -ENODATA;
+	case 1:		/* VCORE IIN/PIN from sensor element */
+	default:
+		return -EOPNOTSUPP;
+	case 2:		/* VSA */
+		switch (reg) {
+		case PMBUS_VIRT_RESET_IOUT_HISTORY:
+			data->iout_avg_pkg = 0xfc00;
+			return 0;
+		case PMBUS_IOUT_OC_FAULT_LIMIT:
+		case PMBUS_IOUT_OC_WARN_LIMIT:
+		case PMBUS_OT_FAULT_LIMIT:
+		case PMBUS_OT_WARN_LIMIT:
+			return i2c_smbus_write_word_data(data->vsa, reg, value);
+		default:
+			return -EOPNOTSUPP;
+		}
+	}
+}
+
+static int max16601_identify(struct i2c_client *client,
+			     struct pmbus_driver_info *info)
+{
+	int reg;
+
+	reg = i2c_smbus_read_byte_data(client, REG_SETPT_DVID);
+	if (reg < 0)
+		return reg;
+	if (reg & DAC_10MV_MODE)
+		info->vrm_version[0] = vr13;
+	else
+		info->vrm_version[0] = vr12;
+
+	return 0;
+}
+
+static struct pmbus_driver_info max16601_info = {
+	.pages = 3,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = vid,
+	.format[PSC_CURRENT_IN] = linear,
+	.format[PSC_CURRENT_OUT] = linear,
+	.format[PSC_TEMPERATURE] = linear,
+	.format[PSC_POWER] = linear,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_PIN |
+		PMBUS_HAVE_STATUS_INPUT |
+		PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP |
+		PMBUS_HAVE_POUT | PMBUS_PAGE_VIRTUAL | PMBUS_PHASE_VIRTUAL,
+	.func[1] = PMBUS_HAVE_IIN | PMBUS_HAVE_PIN | PMBUS_PAGE_VIRTUAL,
+	.func[2] = PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_PAGE_VIRTUAL,
+	.phases[0] = 8,
+	.pfunc[0] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
+	.pfunc[1] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
+	.pfunc[2] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
+	.pfunc[3] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
+	.pfunc[4] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
+	.pfunc[5] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
+	.pfunc[6] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
+	.pfunc[7] = PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT,
+	.identify = max16601_identify,
+	.read_byte_data = max16601_read_byte,
+	.read_word_data = max16601_read_word,
+	.write_byte = max16601_write_byte,
+	.write_word_data = max16601_write_word,
+};
+
+static void max16601_remove(void *_data)
+{
+	struct max16601_data *data = _data;
+
+	i2c_unregister_device(data->vsa);
+}
+
+static int max16601_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
+	struct max16601_data *data;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_BYTE_DATA |
+				     I2C_FUNC_SMBUS_READ_BLOCK_DATA))
+		return -ENODEV;
+
+	ret = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, buf);
+	if (ret < 0)
+		return -ENODEV;
+
+	/* PMBUS_IC_DEVICE_ID is expected to return "MAX16601y.xx" */
+	if (ret < 11 || strncmp(buf, "MAX16601", 8)) {
+		buf[ret] = '\0';
+		dev_err(dev, "Unsupported chip '%s'\n", buf);
+		return -ENODEV;
+	}
+
+	ret = i2c_smbus_read_byte_data(client, REG_PHASE_ID);
+	if (ret < 0)
+		return ret;
+	if (!(ret & CORE_RAIL_INDICATOR)) {
+		dev_err(dev,
+			"Driver must be instantiated on CORE rail I2C address\n");
+		return -ENODEV;
+	}
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->iout_avg_pkg = 0xfc00;
+	data->vsa = i2c_new_dummy_device(client->adapter, client->addr + 1);
+	if (IS_ERR(data->vsa)) {
+		dev_err(dev, "Failed to register VSA client\n");
+		return PTR_ERR(data->vsa);
+	}
+	ret = devm_add_action_or_reset(dev, max16601_remove, data);
+	if (ret)
+		return ret;
+
+	data->info = max16601_info;
+
+	return pmbus_do_probe(client, id, &data->info);
+}
+
+static const struct i2c_device_id max16601_id[] = {
+	{"max16601", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, max16601_id);
+
+static struct i2c_driver max16601_driver = {
+	.driver = {
+		   .name = "max16601",
+		   },
+	.probe = max16601_probe,
+	.remove = pmbus_do_remove,
+	.id_table = max16601_id,
+};
+
+module_i2c_driver(max16601_driver);
+
+MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
+MODULE_DESCRIPTION("PMBus driver for Maxim MAX16601");
+MODULE_LICENSE("GPL v2");