hwmon: (ads7828) driver cleanup

As there is no reliable way to identify the chip, it is preferable to
remove the detect callback, to avoid misdetection.

Module parameters are not worth it here, so let's get rid of them and
add an ads7828_platform_data structure instead.

Clean the code by removing unused macros, fixing coding style issues,
avoiding function prototypes and using convenient macros such as
module_i2c_driver().
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/ads7828

@@ -4,22 +4,33 @@ Kernel driver ads7828
 Supported chips:
   * Texas Instruments/Burr-Brown ADS7828
     Prefix: 'ads7828'
-    Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4b
-    Datasheet: Publicly available at the Texas Instruments website :
+    Datasheet: Publicly available at the Texas Instruments website:
                http://focus.ti.com/lit/ds/symlink/ads7828.pdf
 
 Authors:
         Steve Hardy <shardy@redhat.com>
+        Vivien Didelot <vivien.didelot@savoirfairelinux.com>
 
-Module Parameters
------------------
+Platform data
+-------------
 
-* se_input: bool (default Y)
-  Single ended operation - set to N for differential mode
-* int_vref: bool (default Y)
-  Operate with the internal 2.5V reference - set to N for external reference
-* vref_mv: int (default 2500)
-  If using an external reference, set this to the reference voltage in mV
+The ads7828 driver accepts an optional ads7828_platform_data structure (defined
+in include/linux/platform_data/ads7828.h). The structure fields are:
+
+* diff_input: (bool) Differential operation
+  set to true for differential mode, false for default single ended mode.
+
+* ext_vref: (bool) External reference
+  set to true if it operates with an external reference, false for default
+  internal reference.
+
+* vref_mv: (unsigned int) Voltage reference
+  if using an external reference, set this to the reference voltage in mV,
+  otherwise it will default to the internal value (2500mV). This value will be
+  bounded with limits accepted by the chip, described in the datasheet.
+
+ If no structure is provided, the configuration defaults to single ended
+ operation and internal voltage reference (2.5V).
 
 Description
 -----------
@@ -34,3 +45,7 @@ where 4 differential pairs can be measured.
 The chip also has the facility to use an external voltage reference.  This
 may be required if your hardware supplies the ADS7828 from a 5V supply, see
 the datasheet for more details.
+
+There is no reliable way to identify this chip, so the driver will not scan
+some addresses to try to auto-detect it. That means that you will have to
+statically declare the device in the platform support code.

include/linux/platform_data/ads7828.h

+/*
+ * TI ADS7828 A/D Converter platform data definition
+ *
+ * Copyright (c) 2012 Savoir-faire Linux Inc.
+ *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
+ *
+ * For further information, see the Documentation/hwmon/ads7828 file.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _PDATA_ADS7828_H
+#define _PDATA_ADS7828_H
+
+/**
+ * struct ads7828_platform_data - optional ADS7828 connectivity info
+ * @diff_input:		Differential input mode.
+ * @ext_vref:		Use an external voltage reference.
+ * @vref_mv:		Voltage reference value, if external.
+ */
+struct ads7828_platform_data {
+	bool diff_input;
+	bool ext_vref;
+	unsigned int vref_mv;
+};
+
+#endif /* _PDATA_ADS7828_H */