Subject: [PATCH 0/2] mfd: rsmu_spi: fixes and new IC support

From: Matthew Bystrin <[email-masked]>
Date: Tue, 21 Apr 2026 12:07:08 +0300

Greetings!

First patch fixes Renesas 8A34002 SPI driver.

In my setup 8A34002 is connected to VisionFive2 via SPI. I've discovered that
upstream driver does not work:

[    4.728771] 8a3400x-phc 8a3400x-phc.0.auto: 4.8.7, Id: 0x4002  HW Rev: 5  OTP Config Select: 0
[    4.737389] 8a3400x-phc 8a3400x-phc.0.auto: requesting firmware 'idtcm.bin'
[    4.744462] 8a3400x-phc 8a3400x-phc.0.auto: Direct firmware load for idtcm.bin failed with error -2
[    4.753547] 8a3400x-phc 8a3400x-phc.0.auto: Failed at line 1273 in idtcm_load_firmware!
[    4.761576] 8a3400x-phc 8a3400x-phc.0.auto: loading firmware failed with -2
[    4.769411] 8a3400x-phc 8a3400x-phc.0.auto: No wait state: DPLL_SYS_STATE 0
[    4.776374] 8a3400x-phc 8a3400x-phc.0.auto: Continuing while SYS APLL/DPLL is not locked
[    4.785206] 8a3400x-phc 8a3400x-phc.0.auto: Unsupported MANUAL_REFERENCE: 0x00
[    4.796930] 8a3400x-phc 8a3400x-phc.0.auto: PLL2 registered as ptp0

This being caused by a piece of code in rsmu_write_page_register() function:

if (reg < RSMU_CM_SCSR_BASE)
	return 0;

All addresses in include/linux/mfd/idt8a340_reg.h are less than
RSMU_CM_SCSR_BASE so function was returning early, before any modifications to
the page register. Valid read of versions - is just a coincidence, because
default value of the page register is zero.

There were 2 separate patch series which have to be merged in one time: mfd and
ptp. The latter have been merged, the former[1] have not. As result we've got a
broken driver.

This patch can be reverted later when the second part will be ready (of course
if it is planned to do so). Any comments, Min? I could support with testing.

Also I've had a quick look into I2C part. It may also require the same kind of
fixes to work properly. But I didn't tested it. I could do some experiments and
return with patches later.

Second patch just adds support for 8A34002, which is compatible with 8A34001. As
I can see there is no need to update bindings, everything is already being done.

Link: https://lore.kernel.org/netdev/[email-masked]/
Signed-off-by: Matthew Bystrin <[email-masked]>

Matthew Bystrin (2):
  mfd: rsmu_spi: fix page register setup
  mfd: rsmu_spi: add 8a34002 support

 drivers/mfd/rsmu_spi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

-- 
2.53.0