Re: [PATCH 5/5] arm64: dts: qcom: msm8916-samsung-a2015: Add NFC

[Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>]

On 04/06/2021 19:27, Stephan Gerhold wrote:
> The Samsung Galaxy A3/A5 both have a Samsung S3FWRN5 NFC chip that
> works quite well with the s3fwrn5 driver in the Linux NFC subsystem.
> 
> The clock setup for the NFC chip is a bit special (although this
> seems to be a common approach used for Qualcomm devices with NFC):
> 
> The NFC chip has an output GPIO that is asserted whenever the clock
> is needed to function properly. On the A3/A5 this is wired up to
> PM8916 GPIO2, which is then configured with a special function
> (NFC_CLK_REQ or BB_CLK2_REQ).
> 
> Enabling the rpmcc RPM_SMD_BB_CLK2_PIN clock will then instruct
> PM8916 to automatically enable the clock whenever the NFC chip
> requests it. The advantage is that the clock is only enabled when
> needed and we don't need to manage it ourselves from the NFC driver.
> 
> Note that for some reason Samsung decided to connect the I2C pins
> to GPIOs where no hardware I2C bus is available, so we need to
> fall back to software bit-banging with i2c-gpio.
> 
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> ---
>  .../qcom/msm8916-samsung-a2015-common.dtsi    | 64 +++++++++++++++++++
>  1 file changed, 64 insertions(+)
> 


Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>


Best regards,
Krzysztof