[PATCH 03/20] board: ti: j721e: Add resume detection for J721e/J7200

[Richard GENOUD]

Le 01/06/2026 à 10:29, Thomas Richard a écrit :
> On 4/30/26 10:43 AM, Richard Genoud (TI) wrote:
>> From: "Thomas Richard (TI)" <thomas.richard at bootlin.com>
>>
>> Add the capability to detect a resume. This overrides the weak
>> function j7xx_board_is_resuming(void).
>> To detect the resume, SPL searches a magic value (0xBA) in a register
>> of PMICA.
>> This value is set by DM-Firmware during the suspend sequence.
>>
>> Signed-off-by: Thomas Richard (TI) <thomas.richard at bootlin.com>
>> Co-developed-by: Gregory CLEMENT (TI) <gregory.clement at bootlin.com>
>> Signed-off-by: Gregory CLEMENT (TI) <gregory.clement at bootlin.com>
>> Co-developed-by: Richard Genoud (TI) <richard.genoud at bootlin.com>
>> Signed-off-by: Richard Genoud (TI) <richard.genoud at bootlin.com>
>> ---
>>   board/ti/common/k3-lpm.h | 17 +++++++++++++++++
>>   board/ti/j721e/evm.c     | 37 +++++++++++++++++++++++++++++++++++++
>>   2 files changed, 54 insertions(+)
>>   create mode 100644 board/ti/common/k3-lpm.h
>>
>> diff --git a/board/ti/common/k3-lpm.h b/board/ti/common/k3-lpm.h
>> new file mode 100644
>> index 000000000000..a2141a0c25a8
>> --- /dev/null
>> +++ b/board/ti/common/k3-lpm.h
>> @@ -0,0 +1,17 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ */
>> +/*
>> + * Copyright (C) 2026, Texas Instruments Incorporated - https://www.ti.com/
>> + * Copyright (C) 2026, Bootlin
>> + */
>> +
>> +#ifndef __K3_LPM_H
>> +#define __K3_LPM_H
>> +
>> +/* Magic value in PMIC register to indicate the suspend state (SOC_OFF) */
>> +#define K3_LPM_MAGIC_SUSPEND 0xba
>> +
>> +/* PMIC register where the magic value resides */
>> +#define K3_LPM_SCRATCH_PAD_REG 0xcb
> 
> K3_LPM_SCRATCH_PAD_REG_3 so we easily know it is scratchpad reg 3.
ok

> 
> We currently use the entire SCRATCH_PAD_REG_3 register to mark a resume.
> Some PMICs in certain configurations use some scratchpad registers for
> other purposes, so we could consider using only a specific bit range (or
> even a single bit) and document it. This would free up the remaining
> bits for other uses.
> However, an 8-bit magic value is likely more robust against accidental
> user modification.
> No strong opinion, just raising the topic for discussion.
This is indeed a good point.

Thanks!

> 
> Best Regards,
> Thomas

Regards,
Richars