i2c: mux: Add register-based mux i2c-mux-reg

Based on i2c-mux-gpio driver, similarly the register-based mux
switch from one bus to another by setting a single register.
The register can be on PCIe bus, local bus, or any memory-mapped
address. The endianness of such register can be specified in device
tree if used, or in platform data.

Signed-off-by: York Sun <yorksun@freescale.com>
Acked-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

include/linux/platform_data/i2c-mux-reg.h

@@ -0,0 +1,44 @@
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun <yorksun@freescale.com>
+ *
+ * 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 the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#ifndef __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
+#define __LINUX_PLATFORM_DATA_I2C_MUX_REG_H
+
+/**
+ * struct i2c_mux_reg_platform_data - Platform-dependent data for i2c-mux-reg
+ * @parent: Parent I2C bus adapter number
+ * @base_nr: Base I2C bus number to number adapters from or zero for dynamic
+ * @values: Array of value for each channel
+ * @n_values: Number of multiplexer channels
+ * @little_endian: Indicating if the register is in little endian
+ * @write_only: Reading the register is not allowed by hardware
+ * @classes: Optional I2C auto-detection classes
+ * @idle: Value to write to mux when idle
+ * @idle_in_use: indicate if idle value is in use
+ * @reg: Virtual address of the register to switch channel
+ * @reg_size: register size in bytes
+ */
+struct i2c_mux_reg_platform_data {
+	int parent;
+	int base_nr;
+	const unsigned int *values;
+	int n_values;
+	bool little_endian;
+	bool write_only;
+	const unsigned int *classes;
+	u32 idle;
+	bool idle_in_use;
+	void __iomem *reg;
+	resource_size_t reg_size;
+};
+
+#endif	/* __LINUX_PLATFORM_DATA_I2C_MUX_REG_H */