Merge branch 'i2c-mux/for-next' of https://github.com/peda-r/i2c-mux into i2c/for-4.17

"These patches verify the device id of the PCA984x mux chips using
standardized (but rarely implemented) i2c device identification."

2 files changed, 82 insertions, 6 deletions

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index edfc23e49630..16a3b73375a6 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -58,6 +58,8 @@
 #define I2C_ADDR_7BITS_MAX	0x77
 #define I2C_ADDR_7BITS_COUNT	(I2C_ADDR_7BITS_MAX + 1)
 
+#define I2C_ADDR_DEVICE_ID	0x7c
+
 /*
  * core_lock protects i2c_adapter_idr, and guarantees that device detection,
  * deletion of detected devices, and attach_adapter calls are serialized
@@ -1976,6 +1978,37 @@ int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf,
 }
 EXPORT_SYMBOL(i2c_transfer_buffer_flags);
 
+/**
+ * i2c_get_device_id - get manufacturer, part id and die revision of a device
+ * @client: The device to query
+ * @id: The queried information
+ *
+ * Returns negative errno on error, zero on success.
+ */
+int i2c_get_device_id(const struct i2c_client *client,
+		      struct i2c_device_identity *id)
+{
+	struct i2c_adapter *adap = client->adapter;
+	union i2c_smbus_data raw_id;
+	int ret;
+
+	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
+		return -EOPNOTSUPP;
+
+	raw_id.block[0] = 3;
+	ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0,
+			     I2C_SMBUS_READ, client->addr << 1,
+			     I2C_SMBUS_I2C_BLOCK_DATA, &raw_id);
+	if (ret)
+		return ret;
+
+	id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4);
+	id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3);
+	id->die_revision = raw_id.block[3] & 0x7;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(i2c_get_device_id);
+
 /* ----------------------------------------------------
  * the i2c address scanning function
  * Will not work for 10-bit addresses!
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index fbb84c7ef282..09bafd3e68fa 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -77,6 +77,7 @@ struct chip_desc {
 		pca954x_ismux = 0,
 		pca954x_isswi
 	} muxtype;
+	struct i2c_device_identity id;
 };
 
 struct pca954x {
@@ -97,59 +98,83 @@ static const struct chip_desc chips[] = {
 		.nchans = 2,
 		.enable = 0x4,
 		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9542] = {
 		.nchans = 2,
 		.enable = 0x4,
 		.has_irq = 1,
 		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9543] = {
 		.nchans = 2,
 		.has_irq = 1,
 		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9544] = {
 		.nchans = 4,
 		.enable = 0x4,
 		.has_irq = 1,
 		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9545] = {
 		.nchans = 4,
 		.has_irq = 1,
 		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9546] = {
 		.nchans = 4,
 		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9547] = {
 		.nchans = 8,
 		.enable = 0x8,
 		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9548] = {
 		.nchans = 8,
 		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
 	},
 	[pca_9846] = {
 		.nchans = 4,
 		.muxtype = pca954x_isswi,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x10b,
+		},
 	},
 	[pca_9847] = {
 		.nchans = 8,
 		.enable = 0x8,
 		.muxtype = pca954x_ismux,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x108,
+		},
 	},
 	[pca_9848] = {
 		.nchans = 8,
 		.muxtype = pca954x_isswi,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x10a,
+		},
 	},
 	[pca_9849] = {
 		.nchans = 4,
 		.enable = 0x4,
 		.muxtype = pca954x_ismux,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x109,
+		},
 	},
 };
 
@@ -369,6 +394,30 @@ static int pca954x_probe(struct i2c_client *client,
 	if (IS_ERR(gpio))
 		return PTR_ERR(gpio);
 
+	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
+	if (match)
+		data->chip = of_device_get_match_data(&client->dev);
+	else
+		data->chip = &chips[id->driver_data];
+
+	if (data->chip->id.manufacturer_id != I2C_DEVICE_ID_NONE) {
+		struct i2c_device_identity id;
+
+		ret = i2c_get_device_id(client, &id);
+		if (ret && ret != -EOPNOTSUPP)
+			return ret;
+
+		if (!ret &&
+		    (id.manufacturer_id != data->chip->id.manufacturer_id ||
+		     id.part_id != data->chip->id.part_id)) {
+			dev_warn(&client->dev,
+				 "unexpected device id %03x-%03x-%x\n",
+				 id.manufacturer_id, id.part_id,
+				 id.die_revision);
+			return -ENODEV;
+		}
+	}
+
 	/* Write the mux register at addr to verify
 	 * that the mux is in fact present. This also
 	 * initializes the mux to disconnected state.
@@ -378,12 +427,6 @@ static int pca954x_probe(struct i2c_client *client,
 		return -ENODEV;
 	}
 
-	match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
-	if (match)
-		data->chip = of_device_get_match_data(&client->dev);
-	else
-		data->chip = &chips[id->driver_data];
-
 	data->last_chan = 0;		   /* force the first selection */
 
 	idle_disconnect_dt = of_node &&