linux-kernel - Re: [PATCH 5/9] arm64: dts: meson: g12a: add reset controller

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Message-ID: <5C8D08DE.7070203@baylibre.com>
Date:   Sat, 16 Mar 2019 15:31:58 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Jerome Brunet <jbrunet@...libre.com>
CC:     khilman@...libre.com, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 5/9] arm64: dts: meson: g12a: add reset controller



Le 15/03/2019 22:31, Martin Blumenstingl a écrit :
> Hi Neil and Jerome,
> 
> On Thu, Mar 7, 2019 at 4:14 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>>
>> From: Jerome Brunet <jbrunet@...libre.com>
>>
>> Add the reset controller device of g12a SoC family
>>
>> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  arch/arm64/boot/dts/amlogic/meson-g12a.dtsi | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12a.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12a.dtsi
>> index f8f055c49f9a..2a700bb45d04 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-g12a.dtsi
>> +++ b/arch/arm64/boot/dts/amlogic/meson-g12a.dtsi
>> @@ -245,6 +245,13 @@
>>                         #size-cells = <2>;
>>                         ranges = <0x0 0x0 0x0 0xffd00000 0x0 0x100000>;
>>
>> +                       reset: reset-controller@...4 {
>> +                               compatible = "amlogic,meson-g12a-reset",
>> +                                            "amlogic,meson-axg-reset";
>> +                               reg = <0x0 0x1004 0x0 0x9c>;
>> +                               #reset-cells = <1>;
>> +                       };
> I tried to compare this with what is publicly available in
> buildroot_openlinux_kernel_4.9_fbdev_20180706 - unfortunately this is
> harder than I thought:
> the buildroot kernel doesn't define the reset controller in mesong12a.dtsi
> 
> so I tried to follow the code in the HDMITX driver instead:
> kernel/aml-4.9/drivers/amlogic/media/vout/hdmitx/hdmi_tx_20/hw/hw_txlx.c
> uses P_RESET0_REGISTER and P_RESET2_REGISTER
> these are defined in
> kernel/aml-4.9/drivers/amlogic/media/vout/hdmitx/hdmi_tx_20/hw/txlx_reg.h
> using:
>> #define RESET_CBUS_REG_IDX 5
>> #define BASE_REG_OFFSET 24
>> #define RESET_CBUS_REG_ADDR(reg) \
>>    ((RESET_CBUS_REG_IDX << BASE_REG_OFFSET) + (reg << 2))
>>
>> #define RESET0_REGISTER 0x01
>> #define P_RESET0_REGISTER RESET_CBUS_REG_ADDR(RESET0_REGISTER)
> 
> when I do the maths:
> (5 << 24) + (0x01 << 2) = 0x5000004
> 
> The GX SoCs have the reset controller at cbus + 0x4404
> however, the offset may have changed in G12A because the SAR ADC
> offset also changed (just one example).
> 
> Do you have any hint how to verify the CBUS offset (0x1004) of the
> reset controller?

You can find base the address found in the G12A DT for the usb2 phy :
https://github.com/hardkernel/linux/blob/odroidn2-4.9.y/arch/arm64/boot/dts/amlogic/mesong12a.dtsi#L379

Neil

> 
> 
> Regards
> Martin
>