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From: Peter Rosin <peda@axentia.se>
Date: Mon, 22 Jan 2018 08:32:01 +0100
Subject: i2c: add i2c_get_device_id() to get the standard i2c device id

Git-commit: dde67eb1beebcd8493e7b30e74a80f0865ab7e36
Patch-mainline: v4.17-rc1
References: fate#326530,fate#326531,fate#326535,fate#326538,fate#326539

Can be used during probe to double check that the probed device is
what is expected.

Loosely based on code from Adrian Fiergolski <adrian.fiergolski@cern.ch>.

Tested-by: Adrian Fiergolski <adrian.fiergolski@cern.ch>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/i2c/i2c-core.c |   33 +++++++++++++++++++++++++++++++++
 include/linux/i2c.h    |   30 ++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -68,6 +68,8 @@
 #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 */
@@ -2864,6 +2866,37 @@ int i2c_master_recv(const struct i2c_cli
 }
 EXPORT_SYMBOL(i2c_master_recv);
 
+/**
+ * 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!
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -47,6 +47,7 @@ struct i2c_algorithm;
 struct i2c_adapter;
 struct i2c_client;
 struct i2c_driver;
+struct i2c_device_identity;
 union i2c_smbus_data;
 struct i2c_board_info;
 enum i2c_slave_event;
@@ -128,8 +129,37 @@ extern s32 i2c_smbus_write_i2c_block_dat
 extern s32
 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
 					  u8 command, u8 length, u8 *values);
+int i2c_get_device_id(const struct i2c_client *client,
+		      struct i2c_device_identity *id);
 #endif /* I2C */
 
+/**
+ * struct i2c_device_identity - i2c client device identification
+ * @manufacturer_id: 0 - 4095, database maintained by NXP
+ * @part_id: 0 - 511, according to manufacturer
+ * @die_revision: 0 - 7, according to manufacturer
+ */
+struct i2c_device_identity {
+	u16 manufacturer_id;
+#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS                0
+#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_1              1
+#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_2              2
+#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_3              3
+#define I2C_DEVICE_ID_RAMTRON_INTERNATIONAL             4
+#define I2C_DEVICE_ID_ANALOG_DEVICES                    5
+#define I2C_DEVICE_ID_STMICROELECTRONICS                6
+#define I2C_DEVICE_ID_ON_SEMICONDUCTOR                  7
+#define I2C_DEVICE_ID_SPRINTEK_CORPORATION              8
+#define I2C_DEVICE_ID_ESPROS_PHOTONICS_AG               9
+#define I2C_DEVICE_ID_FUJITSU_SEMICONDUCTOR            10
+#define I2C_DEVICE_ID_FLIR                             11
+#define I2C_DEVICE_ID_O2MICRO                          12
+#define I2C_DEVICE_ID_ATMEL                            13
+#define I2C_DEVICE_ID_NONE                         0xffff
+	u16 part_id;
+	u8 die_revision;
+};
+
 enum i2c_alert_protocol {
 	I2C_PROTOCOL_SMBUS_ALERT,
 	I2C_PROTOCOL_SMBUS_HOST_NOTIFY,