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mb/siemens/mc_ehl8: Disable SPD write protection for RTC access

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The mc_ehl8 variant has an RTC (RV3028-C7) at SMBus address 0x52, which
falls within the SPD EEPROM address range (0x50-0x57). By default, FSP
write-protects this range.

Disable write protection for mc_ehl8 to allow RTC configuration.

TEST=Boot system into OS and use i2ctools to read out registers
     0x00-0x06 of the RTC to verify that the driver set the correct date
     and time.

Change-Id: I0e6426f57d7e316a74102b1e5352ce9d334eac02
Signed-off-by: Kilian Krause <kilian.krause@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/91200
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Kilian Krause 2026-02-13 13:13:34 +01:00 • committed by Matt DeVillier
commit 5db15609a7
1 changed files with 4 additions and 2 deletions
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6
src/mainboard/siemens/mc_ehl/romstage_fsp_params.c
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@ -38,8 +38,10 @@ void mainboard_memory_init_params(FSPM_UPD *memupd)
/* Enable Row-Hammer prevention */
memupd->FspmConfig.RhPrevention = 1;
if (CONFIG(BOARD_SIEMENS_MC_EHL1)) {
/* Allow writes to EEPROM addresses 0x50..0x57. */
if (CONFIG(BOARD_SIEMENS_MC_EHL1) || CONFIG(BOARD_SIEMENS_MC_EHL8)) {
/* Disable write protection for SMBus addresses 0x50-0x57.
* mc_ehl1: Writable SPD EEPROM
* mc_ehl8: RTC at address 0x52 */
memupd->FspmConfig.SmbusSpdWriteDisable = 0;
}
}