[PATCH v4] mhi: host: Add support for dual ELF image format

From: Mayank Rana <[email protected]>

Currently, the FBC image contains a single ELF header followed by segments
for both SBL and WLAN FW. However, TME-L (Trust Management Engine Lite)
supported devices (e.g., QCC2072) require separate ELF headers for SBL and
WLAN FW segments due to TME-L image authentication requirements.

Current image format contains two sections in a single binary:
- First 512KB: ELF header + SBL segments
- Remaining: WLAN FW segments (raw data)

The TME-L supported image format contains two complete ELF files in a
single binary:
- First 512KB: Complete SBL ELF file (ELF header + SBL segments)
- Remaining: Complete WLAN FW ELF file (ELF header + WLAN FW segments)

Download behavior:
- Legacy: 1. First 512KB via BHI (ELF header + SBL)
          2. Full image via BHIe

- TME-L: 1. First 512KB via BHI (SBL ELF file)
         2. Remaining via BHIe (WLAN FW ELF file only)

Add runtime detection to automatically identify the image format by
checking for the presence of a second ELF header at the 512KB boundary.
When detected, MHI skips the first 512KB during WLAN FW download over BHIe
as it is loaded in BHI phase.

Reviewed-by: Baochen Qiang <[email protected]>
Signed-off-by: Mayank Rana <[email protected]>
Co-developed-by: Qiang Yu <[email protected]>
Signed-off-by: Qiang Yu <[email protected]>
---
Changes in v4:
- Detect image format runtime by checking second ELF header instead of using a flag.
- Link to v3: https://lore.kernel.org/r/20251201-wlan_image_load_skip_512k-v3-1-bedb5498a58a@oss.qualcomm.com

Changes in v3:
- Reword commit message.
- Reword comments of standard_elf_image flag
- Add reviewed-by tag.
- Link to v2: https://lore.kernel.org/mhi/20250603-standard_elf_image_load_support-v2-1-cce97644e99e@oss.qualcomm.com/

Changes in v2:
- V1 patch is paused because of no user. WLAN team plan to add support for
  new WLAN chip that requires this patch, so send v2.
- Change author and SOB with new mail address.
- Reword commit message.
- Place standard_elf_image flag after wake_set in struct mhi_controller
- Link to v1: https://lore.kernel.org/mhi/[email protected]/
---
 drivers/bus/mhi/host/boot.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/bus/mhi/host/boot.c b/drivers/bus/mhi/host/boot.c
index 205d83ac069f15a19ab2d66a63692e5d60334d4c..6ba0f16854d3a839e987f19d782600467b5f9836 100644
--- a/drivers/bus/mhi/host/boot.c
+++ b/drivers/bus/mhi/host/boot.c
@@ -584,6 +584,17 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
 	 * device transitioning into MHI READY state
 	 */
 	if (fw_load_type == MHI_FW_LOAD_FBC) {
+
+		/*
+		 * Some FW combine two separate ELF images (SBL + WLAN FW) in a single
+		 * file. Hence, check for the existence of the second ELF header after
+		 * SBL. If present, load the second image separately.
+		 */
+		if (!memcmp(fw_data + mhi_cntrl->sbl_size, ELFMAG, SELFMAG)) {
+			fw_data += mhi_cntrl->sbl_size;
+			fw_sz -= mhi_cntrl->sbl_size;
+		}
+
 		ret = mhi_alloc_bhie_table(mhi_cntrl, &mhi_cntrl->fbc_image, fw_sz);
 		if (ret) {
 			release_firmware(firmware);

---
base-commit: ac35e04f8000aaaf98635792464647e7a6f3422e
change-id: 20251129-wlan_image_load_skip_512k-ddcfe49db8e3

Best regards,
-- 
Qiang Yu <[email protected]>