[U-Boot-Users] [AT91] Problems configuring bit-banged I2C

[U-Boot-Users] [AT91] Problems configuring bit-banged I2C

[Sergey Lapin]

Hi, all!

I use the following patch on my AT91SAM9260-based custom board to
configure bit-banged I2C:

diff --git a/board/atmel/at91sam9260ek/at91sam9260ek.c b/board/atmel/at91sam9260ek/at91sam9260ek.c
index b30aad8..99fc2bd 100644
--- a/board/atmel/at91sam9260ek/at91sam9260ek.c
+++ b/board/atmel/at91sam9260ek/at91sam9260ek.c
@ -234,3 +234,46 @@ void reset_phy(void)
 #endif
 }
 #endif
+
+#define GPIO_I2C_SCL	AT91_PIN_PA24
+#define GPIO_I2C_SDA	AT91_PIN_PA23
+
+void at91sam9260_i2c_init(void)
+{
+	__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_IDR);
+	__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_PUER);
+	__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_PER);
+	__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_MDER);
+	__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_SODR);
+	__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_OER);
+
+	__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_IDR);
+	__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_PUER);
+	__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_PER);
+	__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_MDER);
+	__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_SODR);
+	__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_OER);
+}
+void at91sam9260_i2c_scl(unsigned long bit)
+{
+	if(bit)
+		__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_SODR);
+	 else
+		__raw_writel(pin_to_mask(GPIO_I2C_SCL), pin_to_controller(GPIO_I2C_SCL) + PIO_CODR);
+}
+
+void at91sam9260_i2c_sda(unsigned long bit)
+{
+	printf("Setting %u\n", bit);
+	if(bit)
+		__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_SODR);
+	 else
+		__raw_writel(pin_to_mask(GPIO_I2C_SDA), pin_to_controller(GPIO_I2C_SDA) + PIO_CODR);
+}
+
+int  at91sam9260_i2c_read(void)
+{
+	int c = (__raw_readl(pin_to_controller(GPIO_I2C_SDA) + PIO_PDSR) & pin_to_mask(GPIO_I2C_SDA)) ? 1 : 0;
+	printf("Reading %d\n", c);
+	return c;
+}
diff --git a/include/configs/at91sam9260ek.h b/include/configs/at91sam9260ek.h
index fd9932f..5e66c9e 100644
--- a/include/configs/at91sam9260ek.h
+++ b/include/configs/at91sam9260ek.h
@@ -85,6 +85,8 @@
 
 #define CONFIG_CMD_NAND		1
 #define CONFIG_CMD_USB		1
+#define CONFIG_CMD_I2C		1
+#define CONFIG_I2C_CMD_TREE	1
 
 /* SDRAM */
 #define CONFIG_NR_DRAM_BANKS		1
@ -192,4 +194,20 @@
 #error CONFIG_USE_IRQ not supported
 #endif
 
+/*
+ * Software (bit-bang) I2C driver configuration
+ */
+#define CONFIG_SOFT_I2C		1
+#define CFG_I2C_SPEED		1000000
+#define I2C_INIT		at91sam9260_i2c_init()
+				
+#define I2C_ACTIVE
+#define I2C_TRISTATE
+#define I2C_SCL(bit)	at91sam9260_i2c_scl(bit)
+#define I2C_SDA(bit)	at91sam9260_i2c_sda(bit)
+#define I2C_DELAY	udelay(2)
+#define I2C_READ	at91sam9260_i2c_read()
+#define CFG_I2C_SLAVE		0
+#define DEBUG_I2C
 #endif
+

But I'm unable to read proper values from lines - they always
return 0s. Any ideas on fixing?
Linux i2c-gpio driver works perfectly.

Thanks a lot,
S.

[U-Boot-Users] [AT91] Problems configuring bit-banged I2C

[Jean-Christophe PLAGNIOL-VILLARD]

On 03:36 Sat 24 May     , Sergey Lapin wrote:
> Hi, all!
> 
> I use the following patch on my AT91SAM9260-based custom board to
> configure bit-banged I2C:
> 
> diff --git a/board/atmel/at91sam9260ek/at91sam9260ek.c b/board/atmel/at91sam9260ek/at91sam9260ek.c
> index b30aad8..99fc2bd 100644
> --- a/board/atmel/at91sam9260ek/at91sam9260ek.c
> +++ b/board/atmel/at91sam9260ek/at91sam9260ek.c
> @ -234,3 +234,46 @@ void reset_phy(void)
>  #endif
>  }
>  #endif
Why don't you use the gpio function?
> +
void at91sam9260_i2c_init(void)
{
	at91_set_GPIO_periph(AT91_PIN_PA23, 0);
	at91_set_multi_drive(AT91_PIN_PA23, 1);

	at91_set_A_periph(AT91_PIN_PA24, 0);
	at91_set_multi_drive(AT91_PIN_PA24, 1);
}

void at91sam9260_i2c_scl(unsigned long bit)
{
	at91_set_gpio_value(AT91_PIN_PA24, bit);
}

void at91sam9260_i2c_sda(unsigned long bit)
{
	at91_set_gpio_value(AT91_PIN_PA23, bit)
}
int at91sam9260_i2c_read(void)
{
	retrun at91_get_gpio_value(AT91_PIN_PA23);
}
void at91sam9260_i2c_active()
{
	gpio_direction_output(AT91_PIN_PA23, 0);
}

void at91sam9260_i2c_tristate()
{
	gpio_direction_input(AT91_PIN_PA23);
}
> diff --git a/include/configs/at91sam9260ek.h b/include/configs/at91sam9260ek.h
> index fd9932f..5e66c9e 100644
> --- a/include/configs/at91sam9260ek.h
> +++ b/include/configs/at91sam9260ek.h
> @@ -85,6 +85,8 @@
>  
>  #define CONFIG_CMD_NAND		1
>  #define CONFIG_CMD_USB		1
> +#define CONFIG_CMD_I2C		1
> +#define CONFIG_I2C_CMD_TREE	1
>  
>  /* SDRAM */
>  #define CONFIG_NR_DRAM_BANKS		1
> @ -192,4 +194,20 @@
>  #error CONFIG_USE_IRQ not supported
>  #endif
>  
> +/*
> + * Software (bit-bang) I2C driver configuration
> + */
> +#define CONFIG_SOFT_I2C		1
> +#define CFG_I2C_SPEED		1000000
> +#define I2C_INIT		at91sam9260_i2c_init()
#define I2C_ACTIVE	at91sam9260_i2c_active()
#define I2C_TRISTATE	at91sam9260_i2c_tristate()
> +#define I2C_SCL(bit)	at91sam9260_i2c_scl(bit)
> +#define I2C_SDA(bit)	at91sam9260_i2c_sda(bit)
> +#define I2C_DELAY	udelay(2)
> +#define I2C_READ	at91sam9260_i2c_read()
> +#define CFG_I2C_SLAVE		0
> +#define DEBUG_I2C
>  #endif
> +

I sync it will be better to use the hardware stack which is not too
complicate to implement

Best Regards,
J.

[U-Boot-Users] [AT91] Problems configuring bit-banged I2C

[Haavard Skinnemoen]

Sergey Lapin <slapin@fan.ossfans.org> wrote:
> But I'm unable to read proper values from lines - they always
> return 0s. Any ideas on fixing?
> Linux i2c-gpio driver works perfectly.

Please try this patch:

http://www.nabble.com/-PATCH--soft_i2c%3A-Pull-SDA-high-before-reading-p17270563.html

You shouldn't need to do anything in the I2C_ACTIVE and I2C_TRISTATE
hooks since the PIO is properly configured in open drain mode.

Haavard

[U-Boot-Users] [AT91] Problems configuring bit-banged I2C

[Sergey Lapin]

On Sat, May 24, 2008 at 05:24:00PM +0200, Haavard Skinnemoen wrote:
> Sergey Lapin <slapin@fan.ossfans.org> wrote:
> > But I'm unable to read proper values from lines - they always
> > return 0s. Any ideas on fixing?
> > Linux i2c-gpio driver works perfectly.
> 
> Please try this patch:
> 
> http://www.nabble.com/-PATCH--soft_i2c%3A-Pull-SDA-high-before-reading-p17270563.html
> 
> You shouldn't need to do anything in the I2C_ACTIVE and I2C_TRISTATE
> hooks since the PIO is properly configured in open drain mode.

Alas, I was unable to make bit-banged I2C to work
even with this patch applied. As I mentioned above, it works in
Linux, but I'd like to be able to set time to my RTC from u-boot.
I have checked that pins are configured properly from status registers
(pull-ups are enabled, multi-drive mode is enabled (open drain), etc.).
I could read only zeroes from SDA line in u-boot, and using
oscilloscope, I see data on line. I can't find differencies
in setup with i2c-gpio from Linux. Any ideas?

Thanks a lot,
S.

[U-Boot-Users] [AT91] Problems configuring bit-banged I2C

[Sergey Lapin]

> Why don't you use the gpio function?
Well, I tried to use them but that lead to same result.

> > +
> void at91sam9260_i2c_init(void)
> {
> 	at91_set_GPIO_periph(AT91_PIN_PA23, 0);
> 	at91_set_multi_drive(AT91_PIN_PA23, 1);
> 
> 	at91_set_A_periph(AT91_PIN_PA24, 0);
Why?

> 	at91_set_multi_drive(AT91_PIN_PA24, 1);
> }
> 
> void at91sam9260_i2c_scl(unsigned long bit)
> {
> 	at91_set_gpio_value(AT91_PIN_PA24, bit);
> }
> 
> void at91sam9260_i2c_sda(unsigned long bit)
> {
> 	at91_set_gpio_value(AT91_PIN_PA23, bit)
> }
> int at91sam9260_i2c_read(void)
> {
> 	retrun at91_get_gpio_value(AT91_PIN_PA23);
> }
> void at91sam9260_i2c_active()
> {
> 	gpio_direction_output(AT91_PIN_PA23, 0);
> }
> 
> void at91sam9260_i2c_tristate()
> {
> 	gpio_direction_input(AT91_PIN_PA23);
> }
Thanks a lot for your help, but this did not work either.
iprobe returns full 0x0 - 0x7f range as devices.
Linux i2c-gpio works properly and returns proper set of devices (0x68,
0x50). Is it me or there's bug somewhere?
I can see output values with oscilloscope. I wonder what happens.

> 
> I sync it will be better to use the hardware stack which is not too
> complicate to implement

As commented in Linux kernel about i2c_at91, it is very buggy,
and I was afraid that it could not work for me at all. i2c-gpio works
in Linux. What prevents soft i2c from working ont the same CPU?
This stuff is a mystery for me :(