hwmon: (pmbus/mp2975) Prepare for MP2973 and MP2971

Add support for differntiating between the chips.
The following commits will make use of this mechanism.
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
Link: https://lore.kernel.org/r/20230714135124.2645339-3-Naresh.Solanki@9elements.com
[groeck: double-cast of_device_get_match_data() to make gcc happy]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/pmbus/mp2975.c

@@ -10,6 +10,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of_device.h>
 #include "pmbus.h"
 
 /* Vendor specific registers. */
@@ -56,8 +57,13 @@
 				 PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT | \
 				 PMBUS_HAVE_POUT | PMBUS_PHASE_VIRTUAL)
 
+enum chips {
+	mp2975
+};
+
 struct mp2975_data {
 	struct pmbus_driver_info info;
+	enum chips chip_id;
 	int vout_scale;
 	int vid_step[MP2975_PAGE_NUM];
 	int vref[MP2975_PAGE_NUM];
@@ -68,6 +74,13 @@ struct mp2975_data {
 	int curr_sense_gain[MP2975_PAGE_NUM];
 };
 
+static const struct i2c_device_id mp2975_id[] = {
+	{"mp2975", mp2975},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, mp2975_id);
+
 #define to_mp2975_data(x)  container_of(x, struct mp2975_data, info)
 
 static int mp2975_read_byte_data(struct i2c_client *client, int page, int reg)
@@ -691,6 +704,11 @@ static int mp2975_probe(struct i2c_client *client)
 	if (!data)
 		return -ENOMEM;
 
+	if (client->dev.of_node)
+		data->chip_id = (enum chips)(unsigned long)of_device_get_match_data(&client->dev);
+	else
+		data->chip_id = i2c_match_id(mp2975_id, client)->driver_data;
+
 	memcpy(&data->info, &mp2975_info, sizeof(*info));
 	info = &data->info;
 
@@ -739,15 +757,8 @@ static int mp2975_probe(struct i2c_client *client)
 	return pmbus_do_probe(client, info);
 }
 
-static const struct i2c_device_id mp2975_id[] = {
-	{"mp2975", 0},
-	{}
-};
-
-MODULE_DEVICE_TABLE(i2c, mp2975_id);
-
 static const struct of_device_id __maybe_unused mp2975_of_match[] = {
-	{.compatible = "mps,mp2975"},
+	{.compatible = "mps,mp2975", .data = (void *)mp2975},
 	{}
 };
 MODULE_DEVICE_TABLE(of, mp2975_of_match);