hwmon: (pmbus/max16601) Add support for MAX16508

MAX16508 is quite similar to MAX16601, except that it does not support
the DEFAULT_NUM_POP register and we thus can not dynamically determine
the number of populated phases.

Cc: Alex Qiu <xqiu@google.com>
Cc: Ugur Usug <Ugur.Usug@maximintegrated.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210125185327.93282-2-linux@roeck-us.net
Reviewed-by: Alex Qiu <xqiu@google.com>
Tested-by: Alex Qiu <xqiu@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/max16601.rst

@@ -5,6 +5,14 @@ Kernel driver max16601
 
 Supported chips:
 
+  * Maxim MAX16508
+
+    Prefix: 'max16508'
+
+    Addresses scanned: -
+
+    Datasheet: Not published
+
   * Maxim MAX16601
 
     Prefix: 'max16601'
@@ -19,8 +27,8 @@ Author: Guenter Roeck <linux@roeck-us.net>
 Description
 -----------
 
-This driver supports the MAX16601 VR13.HC Dual-Output Voltage Regulator
-Chipset.
+This driver supports the MAX16508 VR13 Dual-Output Voltage Regulator
+as well as the MAX16601 VR13.HC Dual-Output Voltage Regulator chipsets.
 
 The driver is a client driver to the core PMBus driver.
 Please see Documentation/hwmon/pmbus.rst for details on PMBus client drivers.

drivers/hwmon/pmbus/Kconfig

@@ -158,10 +158,10 @@ config SENSORS_MAX16064
 	  be called max16064.
 
 config SENSORS_MAX16601
-	tristate "Maxim MAX16601"
+	tristate "Maxim MAX16508, MAX16601"
 	help
 	  If you say yes here you get hardware monitoring support for Maxim
-	  MAX16601.
+	  MAX16508 and MAX16601.
 
 	  This driver can also be built as a module. If so, the module will
 	  be called max16601.

drivers/hwmon/pmbus/max16601.c

@@ -1,11 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Hardware monitoring driver for Maxim MAX16601
+ * Hardware monitoring driver for Maxim MAX16508 and 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
+ * This chip series 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.
@@ -31,6 +31,8 @@
 
 #include "pmbus.h"
 
+enum chips { max16508, max16601 };
+
 #define REG_DEFAULT_NUM_POP	0xc4
 #define REG_SETPT_DVID		0xd1
 #define  DAC_10MV_MODE		BIT(4)
@@ -44,6 +46,7 @@
 #define MAX16601_NUM_PHASES	8
 
 struct max16601_data {
+	enum chips id;
 	struct pmbus_driver_info info;
 	struct i2c_client *vsa;
 	int iout_avg_pkg;
@@ -188,6 +191,7 @@ static int max16601_write_word(struct i2c_client *client, int page, int reg,
 static int max16601_identify(struct i2c_client *client,
 			     struct pmbus_driver_info *info)
 {
+	struct max16601_data *data = to_max16601_data(info);
 	int reg;
 
 	reg = i2c_smbus_read_byte_data(client, REG_SETPT_DVID);
@@ -198,6 +202,9 @@ static int max16601_identify(struct i2c_client *client,
 	else
 		info->vrm_version[0] = vr12;
 
+	if (data->id != max16601)
+		return 0;
+
 	reg = i2c_smbus_read_byte_data(client, REG_DEFAULT_NUM_POP);
 	if (reg < 0)
 		return reg;
@@ -254,28 +261,61 @@ static void max16601_remove(void *_data)
 	i2c_unregister_device(data->vsa);
 }
 
-static int max16601_probe(struct i2c_client *client)
+static const struct i2c_device_id max16601_id[] = {
+	{"max16508", max16508},
+	{"max16601", max16601},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, max16601_id);
+
+static int max16601_get_id(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	u8 buf[I2C_SMBUS_BLOCK_MAX + 1];
-	struct max16601_data *data;
+	enum chips id;
 	int ret;
 
+	ret = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, buf);
+	if (ret < 0 || ret < 11)
+		return -ENODEV;
+
+	/*
+	 * PMBUS_IC_DEVICE_ID is expected to return "MAX16601y.xx"
+	 * or "MAX16500y.xx".
+	 */
+	if (!strncmp(buf, "MAX16500", 8)) {
+		id = max16508;
+	} else if (!strncmp(buf, "MAX16601", 8)) {
+		id = max16601;
+	} else {
+		buf[ret] = '\0';
+		dev_err(dev, "Unsupported chip '%s'\n", buf);
+		return -ENODEV;
+	}
+	return id;
+}
+
+static int max16601_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	const struct i2c_device_id *id;
+	struct max16601_data *data;
+	int ret, chip_id;
+
 	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;
+	chip_id = max16601_get_id(client);
+	if (chip_id < 0)
+		return chip_id;
 
-	/* 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;
-	}
+	id = i2c_match_id(max16601_id, client);
+	if (chip_id != id->driver_data)
+		dev_warn(&client->dev,
+			 "Device mismatch: Configured %s (%d), detected %d\n",
+			 id->name, (int) id->driver_data, chip_id);
 
 	ret = i2c_smbus_read_byte_data(client, REG_PHASE_ID);
 	if (ret < 0)
@@ -290,6 +330,7 @@ static int max16601_probe(struct i2c_client *client)
 	if (!data)
 		return -ENOMEM;
 
+	data->id = chip_id;
 	data->iout_avg_pkg = 0xfc00;
 	data->vsa = i2c_new_dummy_device(client->adapter, client->addr + 1);
 	if (IS_ERR(data->vsa)) {
@@ -305,13 +346,6 @@ static int max16601_probe(struct i2c_client *client)
 	return pmbus_do_probe(client, &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",