[PATCH 2/2] ARM: i.MX8MM: add reboot to serial download mode

[Ahmad Fatoum]

On 05.08.21 17:32, Ahmad Fatoum wrote:
> On 03.08.21 18:59, Ahmad Fatoum wrote:
>> The i.MX8MM reference manual follows long established tradition in not
>> documenting BootROM magic reboot codes. For older i.MX variants, the
>> values can be seen in the bmode tables of Freescale's U-Boot patches.
>>
>> There are no such patches for the i.MX8M, but testing shows that
>>
>> 	mw 0x30390094 0x10 ; mw 0x30390098 0x40000000
>>
>> is one of the configurations that trigger serial download on next warm
>> reset on an i.MX8MM. Describe this in the device tree, so
>>
>> 	gpr.reboot_mode.next=serial reset -r imxwd-warm
>>
>> does the right thing for that SoC.
> 
> As you are currently doing i.MX8MP serial boot work, could you apply this
> series, boot barebox containing it (and the i.MX watchdog driver)
> from eMMC and try out:
> 
> 	mw 0x30390094 0x10 ; mw 0x30390098 0x40000000
> 	reset -r imxwd-warm
> 
> If the 8MP is similar enough to the 8MM in this respect, the BootROM
> should fall into serial download mode despite being strapped for
> eMMC.

FTR: The same sequence doesn't work on a 8MP.

> 
> Thanks!
> Ahmad
> 
> 
>>
>> This all might work for other i.MX8M variants as well, but the dtsi
>> can be genericized later on when tested.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
>> ---
>> Cc: David Jander <david at protonic.nl>
>> Cc: Lucas Stach <l.stach at pengutronix.de>
>> ---
>>  Documentation/boards/imx.rst   | 29 +++++++++++++++++++++++++++++
>>  arch/arm/dts/imx8mm-evk.dts    |  1 +
>>  arch/arm/dts/imx8mm-prt8mm.dts |  1 +
>>  arch/arm/dts/imx8mm.dtsi       | 18 ++++++++++++++++++
>>  4 files changed, 49 insertions(+)
>>  create mode 100644 arch/arm/dts/imx8mm.dtsi
>>
>> diff --git a/Documentation/boards/imx.rst b/Documentation/boards/imx.rst
>> index 887b45c70881..4ce9d9808cc1 100644
>> --- a/Documentation/boards/imx.rst
>> +++ b/Documentation/boards/imx.rst
>> @@ -83,6 +83,35 @@ The images can also always be started as second stage on the target:
>>  
>>    barebox at Board Name:/ bootm /mnt/tftp/barebox-freescale-imx51-babbage.img
>>  
>> +BootROM Reboot mode codes (bmode)
>> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> +
>> +For select SoCs, barebox supports communicating an alternative boot medium
>> +that BootROM should select after a warm reset::
>> +
>> +  barebox at FSL i.MX8MM EVK board:/ devinfo gpr.reboot_mode
>> +  Driver: syscon-reboot-mode
>> +  Bus: platform
>> +  Parent: 30390000.reset-controller at 30390000.of
>> +  Parameters:
>> +    next: normal (type: enum) (values: "normal", "serial")
>> +    prev: normal (type: enum) (values: "normal", "serial")
>> +  Device node: /soc at 0/bus at 30000000/reset-controller at 30390000/reboot-mode
>> +  reboot-mode {
>> +          compatible = "barebox,syscon-reboot-mode";
>> +          offset = <0x94 0x98>;
>> +          mask = <0xffffffff 0x40000000>;
>> +          mode-normal = <0x0 0x0>;
>> +          mode-serial = <0x10 0x40000000>;
>> +  };
>> +
>> +  barebox at FSL i.MX8MM EVK board:/ gpr.reboot_mode.next=serial reset -r imxwd-warm
>> +
>> +This will cause barebox to fall into serial download mode on an i.MX8MM.
>> +
>> +Different SoCs may have more possible reboot modes available.
>> +See the section on :ref:`Reboot modes<reboot_mode>` for more information.
>> +
>>  High Assurance Boot
>>  ^^^^^^^^^^^^^^^^^^^
>>  
>> diff --git a/arch/arm/dts/imx8mm-evk.dts b/arch/arm/dts/imx8mm-evk.dts
>> index 1e8619ccf584..304f150307a3 100644
>> --- a/arch/arm/dts/imx8mm-evk.dts
>> +++ b/arch/arm/dts/imx8mm-evk.dts
>> @@ -7,6 +7,7 @@
>>  /dts-v1/;
>>  
>>  #include <arm64/freescale/imx8mm-evk.dts>
>> +#include "imx8mm.dtsi"
>>  
>>  / {
>>  	chosen {
>> diff --git a/arch/arm/dts/imx8mm-prt8mm.dts b/arch/arm/dts/imx8mm-prt8mm.dts
>> index bdcdd0806243..abd758f2856e 100644
>> --- a/arch/arm/dts/imx8mm-prt8mm.dts
>> +++ b/arch/arm/dts/imx8mm-prt8mm.dts
>> @@ -7,6 +7,7 @@
>>  /dts-v1/;
>>  
>>  #include <arm64/freescale/imx8mm.dtsi>
>> +#include "imx8mm.dtsi"
>>  
>>  / {
>>  	model = "Protonic PRT8MM";
>> diff --git a/arch/arm/dts/imx8mm.dtsi b/arch/arm/dts/imx8mm.dtsi
>> new file mode 100644
>> index 000000000000..78bbacb2b1b2
>> --- /dev/null
>> +++ b/arch/arm/dts/imx8mm.dtsi
>> @@ -0,0 +1,18 @@
>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>> +/ {
>> +	aliases {
>> +		gpr.reboot_mode = &reboot_mode_gpr;
>> +	};
>> +};
>> +
>> +&src {
>> +	compatible = "fsl,imx8mm-src", "fsl,imx8mq-src", "syscon", "simple-mfd";
>> +
>> +	reboot_mode_gpr: reboot-mode {
>> +		compatible = "barebox,syscon-reboot-mode";
>> +		offset = <0x94>, <0x98>; /* SRC_GPR{9,10} */
>> +		mask = <0xffffffff>, <0x40000000>;
>> +		mode-normal = <0>, <0>;
>> +		mode-serial = <0x00000010>, <0x40000000>;
>> +	};
>> +};
>>
> 
> 


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