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i2c: soft_i2c: add simple GPIO implementation

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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>
This commit is contained in:
Mike Frysinger 2010-07-21 13:38:02 -04:00 • committed by Heiko Schocher
parent 1f82ff4777
commit 793b5726f7
2 changed files with 62 additions and 0 deletions
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10
README
View file

@ -1495,6 +1495,16 @@ The following options need to be configured:
#define I2C_DELAY udelay(2) #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 CONFIG_SYS_I2C_INIT_BOARD
When a board is reset during an i2c bus transfer When a board is reset during an i2c bus transfer

52
drivers/i2c/soft_i2c.c
View file

@ -51,6 +51,58 @@
#endif #endif
#include <i2c.h> #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 */ /* #define DEBUG_I2C */
#ifdef DEBUG_I2C #ifdef DEBUG_I2C