clk: rs9: Check for vendor/device ID

This is in preparation to support additional devices which have different
IDs as well as a slightly different register layout.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20230310075535.3476580-1-alexander.stein@ew.tq-group.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: tq-steina

drivers/clk/clk-renesas-pcie.c

@@ -45,6 +45,13 @@
 #define RS9_REG_DID				0x6
 #define RS9_REG_BCP				0x7
 
+#define RS9_REG_VID_IDT				0x01
+
+#define RS9_REG_DID_TYPE_FGV			(0x0 << RS9_REG_DID_TYPE_SHIFT)
+#define RS9_REG_DID_TYPE_DBV			(0x1 << RS9_REG_DID_TYPE_SHIFT)
+#define RS9_REG_DID_TYPE_DMV			(0x2 << RS9_REG_DID_TYPE_SHIFT)
+#define RS9_REG_DID_TYPE_SHIFT			0x6
+
 /* Supported Renesas 9-series models. */
 enum rs9_model {
 	RENESAS_9FGV0241,
@@ -54,6 +61,7 @@ enum rs9_model {
 struct rs9_chip_info {
 	const enum rs9_model	model;
 	unsigned int		num_clks;
+	u8			did;
 };
 
 struct rs9_driver_data {
@@ -269,6 +277,7 @@ static int rs9_probe(struct i2c_client *client)
 {
 	unsigned char name[5] = "DIF0";
 	struct rs9_driver_data *rs9;
+	unsigned int vid, did;
 	struct clk_hw *hw;
 	int i, ret;
 
@@ -305,6 +314,20 @@ static int rs9_probe(struct i2c_client *client)
 	if (ret < 0)
 		return ret;
 
+	ret = regmap_read(rs9->regmap, RS9_REG_VID, &vid);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_read(rs9->regmap, RS9_REG_DID, &did);
+	if (ret < 0)
+		return ret;
+
+	if (vid != RS9_REG_VID_IDT || did != rs9->chip_info->did)
+		return dev_err_probe(&client->dev, -ENODEV,
+				     "Incorrect VID/DID: %#02x, %#02x. Expected %#02x, %#02x\n",
+				     vid, did, RS9_REG_VID_IDT,
+				     rs9->chip_info->did);
+
 	/* Register clock */
 	for (i = 0; i < rs9->chip_info->num_clks; i++) {
 		snprintf(name, 5, "DIF%d", i);
@@ -348,6 +371,7 @@ static int __maybe_unused rs9_resume(struct device *dev)
 static const struct rs9_chip_info renesas_9fgv0241_info = {
 	.model		= RENESAS_9FGV0241,
 	.num_clks	= 2,
+	.did		= RS9_REG_DID_TYPE_FGV | 0x02,
 };
 
 static const struct i2c_device_id rs9_id[] = {