i2c: soft_i2c: add simple GPIO implementation

Since the vast majority of GPIO I2C implementations behave the same way,
support the common GPIO framework with default settings.

This adds two new defines CONFIG_SOFT_I2C_GPIO_{SCL,SDA} so that boards
which want GPIO I2C support need only define these.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Tested-by: Thomas Chou <thomas@wytron.com.tw>

diff --git a/README b/README
index a9c98f218e5017543baeebd7f3ad92e0c8dbe976..c9fb284378e9e53acb7f02de8e4cbd1b32c170ec 100644 (file)
--- a/README
+++ b/README
@@ -1495,6 +1495,16 @@ The following options need to be configured:
 
                #define I2C_DELAY  udelay(2)
 
+               CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
+
+               If your arch supports the generic GPIO framework (asm/gpio.h),
+               then you may alternatively define the two GPIOs that are to be
+               used as SCL / SDA.  Any of the previous I2C_xxx macros will
+               have GPIO-based defaults assigned to them as appropriate.
+
+               You should define these to the GPIO value as given directly to
+               the generic GPIO functions.
+
                CONFIG_SYS_I2C_INIT_BOARD
 
                When a board is reset during an i2c bus transfer

diff --git a/drivers/i2c/soft_i2c.c b/drivers/i2c/soft_i2c.c
index e0cf1e10db574830f3fd16838637d3c7ef891215..1a1809ac16ad40c26d7b2dc26f900239af10030d 100644 (file)
--- a/drivers/i2c/soft_i2c.c
+++ b/drivers/i2c/soft_i2c.c
@@ -51,6 +51,58 @@
 #endif
 #include <i2c.h>
 
+#if defined(CONFIG_SOFT_I2C_GPIO_SCL)
+# include <asm/gpio.h>
+
+# ifndef I2C_GPIO_SYNC
+#  define I2C_GPIO_SYNC
+# endif
+
+# ifndef I2C_INIT
+#  define I2C_INIT \
+       do { \
+               gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
+               gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
+       } while (0)
+# endif
+
+# ifndef I2C_ACTIVE
+#  define I2C_ACTIVE do { } while (0)
+# endif
+
+# ifndef I2C_TRISTATE
+#  define I2C_TRISTATE do { } while (0)
+# endif
+
+# ifndef I2C_READ
+#  define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
+# endif
+
+# ifndef I2C_SDA
+#  define I2C_SDA(bit) \
+       do { \
+               if (bit) \
+                       gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
+               else \
+                       gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
+               I2C_GPIO_SYNC; \
+       } while (0)
+# endif
+
+# ifndef I2C_SCL
+#  define I2C_SCL(bit) \
+       do { \
+               gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
+               I2C_GPIO_SYNC; \
+       } while (0)
+# endif
+
+# ifndef I2C_DELAY
+#  define I2C_DELAY udelay(5)  /* 1/4 I2C clock duration */
+# endif
+
+#endif
+
 /* #define     DEBUG_I2C       */
 
 #ifdef DEBUG_I2C