Re: [PATCH v3 11/12] arm64: dts: exynos: gs101: define USI8 with I2C configuration

Tudor Ambarus
2024-01-17T15:08:31Z

On 1/16/24 18:03, Sam Protsenko wrote:
>> USI8 CONFIG register comes with a 0x0 reset value, meaning that USI8
>> doesn't have a default protocol (I2C, SPI, UART) at reset. Thus the
>> selection of the protocol is intentionally left for the board dts file.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
>> ---
>> v3: reorder usi8 clock order (thanks Andre'!). Did not make any
>> difference at testing as the usi driver treats the clocks in bulk.
>> v2:
>> - identify and use gate clocks instead of dividers
>> - move cells and pinctrl properties from dts to dtsi
>> - move IRQ type constant on the previous line
>>
>> arch/arm64/boot/dts/exynos/google/gs101.dtsi | 29 ++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> index 6aa25cc4676e..f14a24628d04 100644
>> --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> @@ -352,6 +352,35 @@ pinctrl_peric0: pinctrl@10840000 {
>> interrupts = <GIC_SPI 625 IRQ_TYPE_LEVEL_HIGH 0>;
>> };
>>
>> + usi8: usi@109700c0 {
>> + compatible = "google,gs101-usi",
>> + "samsung,exynos850-usi";
>> + reg = <0x109700c0 0x20>;
>> + ranges;
>> + #address-cells = <1>;
>> + #size-cells = <1>;
>> + clocks = <&cmu_peric0 CLK_GOUT_PERIC0_CLK_PERIC0_USI8_USI_CLK>,
>> + <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_7>;
>> + clock-names = "pclk", "ipclk";
>> + samsung,sysreg = <&sysreg_peric0 0x101c>;
> I'd also add samsung,mode for the "default" USI mode here, just to
> avoid providing it later in the board's dts. But that's a matter of
> taste I guess.
>

USI8 CONFIG register comes with a 0x0 reset value, meaning that USI8
doesn't have a default protocol (I2C, SPI, UART) at reset. Thus the
selection of the protocol is intentionally left for the board dts file.

I wanted to emphasize that USI8 doesn't have any HW defaults and its
mode must be chosen by each particular board.

I mentioned the same in the commit message, please tell if you feel it
needs updating.

Cheers,
ta