On Sat, 2007-03-10 at 14:13 +0100, Haavard Skinnemoen wrote:
> This is a very simple bitbanging i2c bus driver utilizing the new
> arch-neutral GPIO API. Useful for chips that don't have a built-in
> i2c controller, additional i2c busses, or testing purposes.
>
Sorry for missing this hot discussion. Your idea is exactly what I want.
So many arch specific GPIO based I2C adapter implementation will benefit
from this.
> To use, include something similar to the following in the
> board-specific setup code:
>
> #include <linux/i2c-gpio.h>
>
> static struct i2c_gpio_platform_data i2c_gpio_data = {
> .sda_pin = GPIO_PIN_FOO,
> .scl_pin = GPIO_PIN_BAR,
> };
Is this usage right, because 3 flags are added to this structure as
below:
struct i2c_gpio_platform_data {
unsigned int sda_pin;
unsigned int scl_pin;
unsigned int sda_is_open_drain:1;
unsigned int scl_is_open_drain:1;
unsigned int scl_is_output_only:1;
};
> static struct platform_device i2c_gpio_device = {
> .name = "i2c-gpio",
> .id = 0,
> .dev = {
> .platform_data = &i2c_gpio_data,
> },
> };
>
> Register this platform_device, set up the i2c pins as GPIO if
> required and you're ready to go.
>
> Signed-off-by: Haavard Skinnemoen <[EMAIL PROTECTED]>
> ---
> This patch is different from the first patch in the following ways:
> * Handles pins set up as open drain (aka multidrive) by toggling
> the output value instead of the direction
> * Handles output-only SCL pins the same way, and also does not
> install a getscl() callback for such pins
> * Does not add anything to include/linux/i2c-ids.h
> * Sets the output value explicitly after changing the direction to
> output.
> * Plugs a memory leak in remove() -- algo_data wasn't freed.
> * Prints out the pin IDs in decimal, with an extra note when clock
> stretching isn't supported
>
> This version has been compile-tested only. I'll give it a spin when I
> get back to work on monday.
>
> Dave, does this address your concerns?
>
> Haavard
Thanks a lot, I will drop our GPIO based I2C driver and try this one on
our platform.
> + if (!pdata->scl_is_output_only)
> + bit_data->getscl = i2c_gpio_getscl,
> +
> + bit_data->getsda = i2c_gpio_getsda,
> + bit_data->udelay = 5, /* 100 kHz */
> + bit_data->timeout = HZ / 10, /* 100 ms */
Can we add these udelay/timeout to struct i2c_gpio_platform_data? And
let customer to choose these according their specific requirement. We
use Kconfig to do this, but Jean and David don't like the idea, -:(
Regards,
-Bryan Wu
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