From fae8034962edf607151ec811ed78b1d932c1c908 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@roeck-us.net>
Date: Fri, 6 Sep 2013 09:28:45 -0700
Subject: [PATCH] Update compat.h to improve support of older kernels.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 compat.h | 140 +++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 132 insertions(+), 8 deletions(-)

diff --git a/compat.h b/compat.h
index 03cb1ff..b18f4e2 100644
--- a/compat.h
+++ b/compat.h
@@ -1,13 +1,137 @@
-/*---------------------------------------------------------------------------
- * 
- * compat.h 
- *     Copyright (c) 2012 Guenter Roeck <linux@roeck-us.net>
+#ifndef __COMPAT_H
+#define __COMPAT_H
+
+#include <linux/version.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 16)
+#error This driver is for kernel versions 2.6.16 and later
+#endif
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 21)
+#if !(defined RHEL_MAJOR && RHEL_MAJOR == 5 && RHEL_MINOR >= 6)
+/* Simplified version for compatibility */
+struct i2c_board_info {
+	char		type[I2C_NAME_SIZE];
+	unsigned short	flags;
+	unsigned short	addr;
+};
+#endif
+#endif
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 25)
+/* Some older kernels have a different, useless struct i2c_device_id */
+#define i2c_device_id i2c_device_id_compat
+struct i2c_device_id {
+	char name[I2C_NAME_SIZE];
+	kernel_ulong_t driver_data      /* Data private to the driver */
+			__attribute__((aligned(sizeof(kernel_ulong_t))));
+};
+#endif
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 32)
+static unsigned short empty_i2c[] =  { I2C_CLIENT_END };
+static struct i2c_client_address_data addr_data = {
+	.normal_i2c	= normal_i2c,
+	.probe		= empty_i2c,
+	.ignore		= empty_i2c,
+};
+#endif
+
+/* Red Hat EL5 includes backports of these functions, so we can't redefine
+ * our own. */
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 24)
+#if !(defined RHEL_MAJOR && RHEL_MAJOR == 5 && RHEL_MINOR >= 5)
+static inline int strict_strtoul(const char *cp, unsigned int base,
+				 unsigned long *res)
+{
+	*res = simple_strtoul(cp, NULL, base);
+	return 0;
+}
+
+static inline int strict_strtol(const char *cp, unsigned int base, long *res)
+{
+	*res = simple_strtol(cp, NULL, base);
+	return 0;
+}
+#endif
+#endif
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 28)
+/*
+ * Divide positive or negative dividend by positive divisor and round
+ * to closest integer. Result is undefined for negative divisors and
+ * for negative dividends if the divisor variable type is unsigned.
+ */
+#define DIV_ROUND_CLOSEST(x, divisor)(			\
+{							\
+	typeof(x) __x = x;				\
+	typeof(divisor) __d = divisor;			\
+	(((typeof(x))-1) > 0 ||				\
+	 ((typeof(divisor))-1) > 0 || (__x) > 0) ?	\
+		(((__x) + ((__d) / 2)) / (__d)) :	\
+		(((__x) - ((__d) / 2)) / (__d));	\
+}							\
+)
+#endif
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 2, 0)
+static inline s32
+i2c_smbus_read_word_swapped(const struct i2c_client *client, u8 command)
+{
+	s32 value = i2c_smbus_read_word_data(client, command);
+
+	return (value < 0) ? value : swab16(value);
+}
+
+static inline s32
+i2c_smbus_write_word_swapped(const struct i2c_client *client,
+			     u8 command, u16 value)
+{
+	return i2c_smbus_write_word_data(client, command, swab16(value));
+}
+#endif
+
+#ifndef module_driver
+/**
+ * module_driver() - Helper macro for drivers that don't do anything
+ * special in module init/exit. This eliminates a lot of boilerplate.
+ * Each module may only use this macro once, and calling it replaces
+ * module_init() and module_exit().
+ *
+ * @__driver: driver name
+ * @__register: register function for this driver type
+ * @__unregister: unregister function for this driver type
+ * @...: Additional arguments to be passed to __register and __unregister.
  *
- *---------------------------------------------------------------------------
+ * Use this macro to construct bus specific macros for registering
+ * drivers, and do not use it on its own.
  */
+#define module_driver(__driver, __register, __unregister, ...) \
+static int __init __driver##_init(void) \
+{ \
+	return __register(&(__driver) , ##__VA_ARGS__); \
+} \
+module_init(__driver##_init); \
+static void __exit __driver##_exit(void) \
+{ \
+	__unregister(&(__driver) , ##__VA_ARGS__); \
+} \
+module_exit(__driver##_exit);
+#endif
 
-#ifndef COMPAT_H
-#define COMPAT_H
+#ifndef module_i2c_driver
+/**
+ * module_i2c_driver() - Helper macro for registering a I2C driver
+ * @__i2c_driver: i2c_driver struct
+ *
+ * Helper macro for I2C drivers which do not do anything special in module
+ * init/exit. This eliminates a lot of boilerplate. Each module may only
+ * use this macro once, and calling it replaces module_init() and module_exit()
+ */
+#define module_i2c_driver(__i2c_driver) \
+	module_driver(__i2c_driver, i2c_add_driver, \
+			i2c_del_driver)
+#endif
 
 #ifndef clamp_val
 #define clamp_val SENSORS_LIMIT
@@ -25,4 +149,4 @@
 #define release_region(a, b)
 #endif
 
-#endif /* COMPAT_H */
+#endif /* __COMPAT_H */
-- 
2.39.5