[PATCH v9 07/13] arm: mach-k3: am62xx-lpm-common: Helper for LPM meta data address from DT

[Akashdeep Kaur]

Hi Andrew,

On 06/01/26 22:53, Andrew Davis wrote:
> On 1/5/26 10:38 AM, Markus Schneider-Pargmann (TI.com) wrote:
>> Add a small helper that uses memory regions referenced by the R5
>> devicetree node to calculate the LPM meta data address.
>>
>> Signed-off-by: Markus Schneider-Pargmann (TI.com) <msp at baylibre.com>
>> ---
>>   arch/arm/mach-k3/am62xx-lpm-common.c | 45 ++++++++++++++++++++++++++ 
>> ++++++++++
>>   arch/arm/mach-k3/am62xx-lpm-common.h |  1 +
>>   2 files changed, 46 insertions(+)
>>
>> diff --git a/arch/arm/mach-k3/am62xx-lpm-common.c b/arch/arm/mach-k3/ 
>> am62xx-lpm-common.c
>> index 
>> fa068c60ce9ccf9cec89aeae1d224b07091a3298..6870395aec838949b5c25a32262a6c30e6c88d2e 100644
>> --- a/arch/arm/mach-k3/am62xx-lpm-common.c
>> +++ b/arch/arm/mach-k3/am62xx-lpm-common.c
>> @@ -9,6 +9,8 @@
>>   #include <config.h>
>>   #include <asm/arch/hardware.h>
>>   #include <asm/io.h>
>> +#include <dm/of_access.h>
>> +#include <dm/ofnode.h>
>>   #include <linux/soc/ti/ti_sci_protocol.h>
>>   #include <vsprintf.h>
>>   #include <wait_bit.h>
>> @@ -48,6 +50,8 @@
>>   #define WKUP_CTRL_MMR_CANUART_WAKE_OFF_MODE_STAT        0x18318
>>   #define WKUP_CTRL_MMR_CANUART_WAKE_OFF_MODE_STAT_MW        0x555555
>> +#define K3_R5_MEMREGION_LPM_METADATA_OFFSET    0x108000
>> +
> 
> Could this offset into the R5's second reserved memory area change based
> on the firmware used? Actually this whole thing feels hacky. Why not
> just add the location to DT explicitly instead of trying to derive it.

The offset value of LPM Metadata in linker file will always be relative 
to the position of DM's reserved memory region in DDR.

Reference: 
https://github.com/TexasInstruments/mcupsdk-core-k3/blob/k3_main/examples/drivers/ipc/ipc_rpmsg_echo_linux/am62ax-sk/r5fss0-0_freertos/ti-arm-clang/linker.cmd#L169

> 
> Actually, don't we pick this address as part of the 
> TISCI_MSG_PREPARE_SLEEP?

This is not done as a part of PREPARE SLEEP message. As DM is the one 
reserving static memory for LPM, it is already aware of the address 
where context needs to be saved.

> Or does DM do it now, either way there must be some better way to 
> coordinate
> between DM and R5 SPL than hardcoded offsets..
> 
> Andrew
> 
>>   #define CLKSTOP_TRANSITION_TIMEOUT_MS    10
>>   static int wkup_ctrl_remove_can_io_isolation(void)
>> @@ -126,6 +130,43 @@ int __maybe_unused 
>> wkup_ctrl_remove_can_io_isolation_if_set(void)
>>   }
>>   #if IS_ENABLED(CONFIG_K3_IODDR)
>> +int wkup_r5f_am62_lpm_meta_data_addr(u64 *meta_data_addr)
>> +{
>> +    struct ofnode_phandle_args memregion_phandle;
>> +    ofnode memregion;
>> +    ofnode wkup_bus;
>> +    int ret;
>> +
>> +    wkup_bus = ofnode_path("/bus at f0000/bus at b00000");
>> +    if (!ofnode_valid(wkup_bus)) {
>> +        printf("Failed to find wkup bus\n");
>> +        return -EINVAL;
>> +    }
>> +
>> +    memregion = ofnode_by_compatible(wkup_bus, "ti,am62-r5f");
>> +    if (!ofnode_valid(memregion)) {
>> +        printf("Failed to find r5f devicetree node ti,am62-r5f\n");
>> +        return -EINVAL;
>> +    }
>> +
>> +    ret = ofnode_parse_phandle_with_args(memregion, "memory-region", 
>> NULL,
>> +                         0, 1, &memregion_phandle);
>> +    if (ret) {
>> +        printf("Failed to parse phandle for second memory region\n");
>> +        return ret;
>> +    }
>> +
>> +    ret = ofnode_read_u64_index(memregion_phandle.node, "reg", 0, 
>> meta_data_addr);
>> +    if (ret) {
>> +        printf("Failed to read memory region offset\n");
>> +        return ret;
>> +    }
>> +
>> +    *meta_data_addr += K3_R5_MEMREGION_LPM_METADATA_OFFSET;
>> +
...

Thanks and Regards,
Akashdeep Kaur