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authorPeter Korsgaard <peter.korsgaard@barco.com>2011-01-10 22:11:23 +0100
committerJean Delvare <khali@endymion.delvare>2011-01-10 22:11:23 +0100
commit92ed1a76ca31774eb27de14b2215841367c68056 (patch)
treef9becefa5dbcdaa8cfd65100e1735044cd3910d6 /include
parentb18a5c80eb2e7e9c72d23f1960b09d78ddf7e5b0 (diff)
i2c: Add generic I2C multiplexer using GPIO API
Add an i2c mux driver providing access to i2c bus segments using a hardware MUX sitting on a master bus and controlled through gpio pins. E.G. something like: ---------- ---------- Bus segment 1 - - - - - | | SCL/SDA | |-------------- | | | |------------| | | | | | Bus segment 2 | | | Linux | GPIO 1..N | MUX |--------------- Devices | |------------| | | | | | | | Bus segment M | | | |---------------| | ---------- ---------- - - - - - SCL/SDA of the master I2C bus is multiplexed to bus segment 1..M according to the settings of the GPIO pins 1..N. Signed-off-by: Peter Korsgaard <peter.korsgaard@barco.com> Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/gpio-i2cmux.h38
1 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/gpio-i2cmux.h b/include/linux/gpio-i2cmux.h
new file mode 100644
index 00000000000..4a333bb0bd0
--- /dev/null
+++ b/include/linux/gpio-i2cmux.h
@@ -0,0 +1,38 @@
+/*
+ * gpio-i2cmux interface to platform code
+ *
+ * Peter Korsgaard <peter.korsgaard@barco.com>
+ *
+ * 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 _LINUX_GPIO_I2CMUX_H
+#define _LINUX_GPIO_I2CMUX_H
+
+/* MUX has no specific idle mode */
+#define GPIO_I2CMUX_NO_IDLE ((unsigned)-1)
+
+/**
+ * struct gpio_i2cmux_platform_data - Platform-dependent data for gpio-i2cmux
+ * @parent: Parent I2C bus adapter number
+ * @base_nr: Base I2C bus number to number adapters from or zero for dynamic
+ * @values: Array of bitmasks of GPIO settings (low/high) for each
+ * position
+ * @n_values: Number of multiplexer positions (busses to instantiate)
+ * @gpios: Array of GPIO numbers used to control MUX
+ * @n_gpios: Number of GPIOs used to control MUX
+ * @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used
+ */
+struct gpio_i2cmux_platform_data {
+ int parent;
+ int base_nr;
+ const unsigned *values;
+ int n_values;
+ const unsigned *gpios;
+ int n_gpios;
+ unsigned idle;
+};
+
+#endif /* _LINUX_GPIO_I2CMUX_H */