ENGR00277864 input: mma8450: Add chip id check in probe

Add chip ID check in probe function. The mma8450 is
on the E-INK daughter board. When the daughter board
is not pluged, there would be polling error log
continuously. Add the check to avoid this.

Signed-off-by: Luwei Zhou <b45643@freescale.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/drivers/input/misc/mma8450.c b/drivers/input/misc/mma8450.c
index f3309696d053..9d3868211fc2 100644
--- a/drivers/input/misc/mma8450.c
+++ b/drivers/input/misc/mma8450.c
@@ -1,7 +1,7 @@
 /*
  *  Driver for Freescale's 3-Axis Accelerometer MMA8450
  *
- *  Copyright (C) 2011 Freescale Semiconductor, Inc. All Rights Reserved.
+ *  Copyright (C) 2011-2013 Freescale Semiconductor, Inc. All Rights Reserved.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -51,6 +51,8 @@
 
 #define MMA8450_CTRL_REG1       0x38
 #define MMA8450_CTRL_REG2       0x39
+#define MMA8450_ID              0xC6
+#define MMA8450_WHO_AM_I        0x0F
 
 /* mma8450 status */
 struct mma8450 {
@@ -172,7 +174,25 @@ static int mma8450_probe(struct i2c_client *c,
 {
         struct input_polled_dev *idev;
         struct mma8450 *m;
-        int err;
+        int err, client_id;
+        struct i2c_adapter *adapter = NULL;
+
+        adapter = to_i2c_adapter(c->dev.parent);
+        err = i2c_check_functionality(adapter,
+                                         I2C_FUNC_SMBUS_BYTE |
+                                         I2C_FUNC_SMBUS_BYTE_DATA);
+        if (!err)
+                goto err_out;
+
+        client_id = i2c_smbus_read_byte_data(c, MMA8450_WHO_AM_I);
+
+        if (MMA8450_ID != client_id) {
+                dev_err(&c->dev,
+                        "read chip ID 0x%x is not equal to 0x%x!\n", client_id,
+                        MMA8450_ID);
+                err = -EINVAL;
+                goto err_out;
+        }
 
         m = kzalloc(sizeof(struct mma8450), GFP_KERNEL);
         idev = input_allocate_polled_device();
@@ -209,6 +229,7 @@ static int mma8450_probe(struct i2c_client *c,
 err_free_mem:
         input_free_polled_device(idev);
         kfree(m);
+err_out:
         return err;
 }