diff mbox

[v7,3/5] ARM: dts: stm32: Add I2C1 support for STM32F429 SoC

Message ID 1482413704-17531-4-git-send-email-cedric.madianga@gmail.com
State Superseded
Headers show

Commit Message

M'boumba Cedric Madianga Dec. 22, 2016, 1:35 p.m. UTC 
This patch adds I2C1 support for STM32F429 SoC

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
---
 arch/arm/boot/dts/stm32f429.dtsi | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

Comments

Uwe Kleine-König Dec. 22, 2016, 7:11 p.m. UTC | #1 
Hello,

On Thu, Dec 22, 2016 at 02:35:02PM +0100, M'boumba Cedric Madianga wrote:
> @@ -337,6 +350,16 @@
>  					slew-rate = <2>;
>  				};
>  			};
> +
> +			i2c1_pins_b: i2c1@0 {
> +				pins1 {
> +					pinmux = <STM32F429_PB9_FUNC_I2C1_SDA>;
> +					drive-open-drain;
> +				};
> +				pins2 {
> +					pinmux = <STM32F429_PB6_FUNC_I2C1_SCL>;
> +				};

the second doesn't need the open-drain property? Why?

> +			};
>  		};

Best regards
Uwe
M'boumba Cedric Madianga Dec. 23, 2016, 1:09 p.m. UTC | #2 
Hi,


2016-12-22 20:11 GMT+01:00 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:
> Hello,
>
> On Thu, Dec 22, 2016 at 02:35:02PM +0100, M'boumba Cedric Madianga wrote:
>> @@ -337,6 +350,16 @@
>>                                       slew-rate = <2>;
>>                               };
>>                       };
>> +
>> +                     i2c1_pins_b: i2c1@0 {
>> +                             pins1 {
>> +                                     pinmux = <STM32F429_PB9_FUNC_I2C1_SDA>;
>> +                                     drive-open-drain;
>> +                             };
>> +                             pins2 {
>> +                                     pinmux = <STM32F429_PB6_FUNC_I2C1_SCL>;
>> +                             };
>
> the second doesn't need the open-drain property? Why?
I thought that open-drain was only needed for SDA line.
But after double-checking I2C specification, it seems that SDA and SCL
lines need open-drain or open-collector to perform the wired-AND
function.
I will do some trials with this config and will fix it in the V8.
Thanks

>
>> +                     };
>>               };
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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Linus Walleij Dec. 30, 2016, 9:07 a.m. UTC | #3 
On Fri, Dec 23, 2016 at 2:09 PM, M'boumba Cedric Madianga
<cedric.madianga@gmail.com> wrote:
> 2016-12-22 20:11 GMT+01:00 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:
>> On Thu, Dec 22, 2016 at 02:35:02PM +0100, M'boumba Cedric Madianga wrote:
>>> @@ -337,6 +350,16 @@
>>>                                       slew-rate = <2>;
>>>                               };
>>>                       };
>>> +
>>> +                     i2c1_pins_b: i2c1@0 {
>>> +                             pins1 {
>>> +                                     pinmux = <STM32F429_PB9_FUNC_I2C1_SDA>;
>>> +                                     drive-open-drain;
>>> +                             };
>>> +                             pins2 {
>>> +                                     pinmux = <STM32F429_PB6_FUNC_I2C1_SCL>;
>>> +                             };
>>
>> the second doesn't need the open-drain property? Why?
>
> I thought that open-drain was only needed for SDA line.
> But after double-checking I2C specification, it seems that SDA and SCL
> lines need open-drain or open-collector to perform the wired-AND
> function.

I think I2C SDA/SCL must be open drain by definition.

It also requires pull-up resistors, I guess you have these mounted on the board
so you do not need pull-up from the pin controller?

Yours,
Linus Walleij
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M'boumba Cedric Madianga Dec. 30, 2016, 2:36 p.m. UTC | #4 
Hi Linus,

2016-12-30 10:07 GMT+01:00 Linus Walleij <linus.walleij@linaro.org>:
> On Fri, Dec 23, 2016 at 2:09 PM, M'boumba Cedric Madianga
> <cedric.madianga@gmail.com> wrote:
>> 2016-12-22 20:11 GMT+01:00 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:
>>> On Thu, Dec 22, 2016 at 02:35:02PM +0100, M'boumba Cedric Madianga wrote:
>>>> @@ -337,6 +350,16 @@
>>>>                                       slew-rate = <2>;
>>>>                               };
>>>>                       };
>>>> +
>>>> +                     i2c1_pins_b: i2c1@0 {
>>>> +                             pins1 {
>>>> +                                     pinmux = <STM32F429_PB9_FUNC_I2C1_SDA>;
>>>> +                                     drive-open-drain;
>>>> +                             };
>>>> +                             pins2 {
>>>> +                                     pinmux = <STM32F429_PB6_FUNC_I2C1_SCL>;
>>>> +                             };
>>>
>>> the second doesn't need the open-drain property? Why?
>>
>> I thought that open-drain was only needed for SDA line.
>> But after double-checking I2C specification, it seems that SDA and SCL
>> lines need open-drain or open-collector to perform the wired-AND
>> function.
>
> I think I2C SDA/SCL must be open drain by definition.
>
> It also requires pull-up resistors, I guess you have these mounted on the board
> so you do not need pull-up from the pin controller?
Yes, I have 1 pull-up resistor of 1,5K ohm for each line (SDA & SCL)
on the board

>
> Yours,
> Linus Walleij
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diff mbox

Patch

diff --git a/arch/arm/boot/dts/stm32f429.dtsi b/arch/arm/boot/dts/stm32f429.dtsi
index 7de52ee..2277a2d 100644
--- a/arch/arm/boot/dts/stm32f429.dtsi
+++ b/arch/arm/boot/dts/stm32f429.dtsi
@@ -48,6 +48,7 @@ 
 #include "skeleton.dtsi"
 #include "armv7-m.dtsi"
 #include <dt-bindings/pinctrl/stm32f429-pinfunc.h>
+#include <dt-bindings/mfd/stm32f4-rcc.h>
 
 / {
 	clocks {
@@ -140,6 +141,18 @@ 
 			status = "disabled";
 		};
 
+		i2c1: i2c@40005400 {
+			compatible = "st,stm32f4-i2c";
+			reg = <0x40005400 0x400>;
+			interrupts = <31>,
+				     <32>;
+			resets = <&rcc STM32F4_APB1_RESET(I2C1)>;
+			clocks = <&rcc 0 STM32F4_APB1_CLOCK(I2C1)>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "disabled";
+		};
+
 		usart7: serial@40007800 {
 			compatible = "st,stm32-usart", "st,stm32-uart";
 			reg = <0x40007800 0x400>;
@@ -337,6 +350,16 @@ 
 					slew-rate = <2>;
 				};
 			};
+
+			i2c1_pins_b: i2c1@0 {
+				pins1 {
+					pinmux = <STM32F429_PB9_FUNC_I2C1_SDA>;
+					drive-open-drain;
+				};
+				pins2 {
+					pinmux = <STM32F429_PB6_FUNC_I2C1_SCL>;
+				};
+			};
 		};
 
 		rcc: rcc@40023810 {