[PATCH v3] mhi: host: Add standard elf image download functionality

From: Mayank Rana <[email protected]>

Currently, the FBC image is a non-standard ELF file that contains a single
ELF header, followed by segments for SBL, and WLAN FW. However, TME-L
(Trust Management Engine Lite) supported devices (eg. QCC2072) requires
separate ELF headers for SBL and WLAN FW segments due to TME-L image
authentication requirement.

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

The TME-L supported image format contains two sections with two elf
headers in a single binary:
- First 512KB: First ELF header + SBL segments
- Remaining: Second 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 (First ELF header + SBL)
         2. Remaining via BHIe (Second ELF header + WLAN FW segments)

Add standard_elf_image flag to mhi_controller_config to indicate TME-L
supported image format. When set, 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 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 | 7 +++++++
 include/linux/mhi.h         | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/drivers/bus/mhi/host/boot.c b/drivers/bus/mhi/host/boot.c
index 205d83ac069f15a19ab2d66a63692e5d60334d4c..64fb7a257d3529167eddf1153d34cc6b25735809 100644
--- a/drivers/bus/mhi/host/boot.c
+++ b/drivers/bus/mhi/host/boot.c
@@ -584,6 +584,13 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
 	 * device transitioning into MHI READY state
 	 */
 	if (fw_load_type == MHI_FW_LOAD_FBC) {
+		dev_dbg(dev, "standard_elf_image:%s\n",
+			(mhi_cntrl->standard_elf_image ? "True" : "False"));
+		if (mhi_cntrl->standard_elf_image) {
+			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);
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index dd372b0123a6da5107b807ff8fe940c567eb2030..a13106bb234d22e3876dff3c0d46f3dee1d9e05c 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -360,6 +360,9 @@ struct mhi_controller_config {
  * @bounce_buf: Use of bounce buffer
  * @fbc_download: MHI host needs to do complete image transfer (optional)
  * @wake_set: Device wakeup set flag
+ * @standard_elf_image: Flag to determine whether the first 512 KB of the FBC
+ *                      image need to be skipped when loading WLAN FW over
+ *                      BHIe interface (optional)
  * @irq_flags: irq flags passed to request_irq (optional)
  * @mru: the default MRU for the MHI device
  *
@@ -445,6 +448,7 @@ struct mhi_controller {
 	bool bounce_buf;
 	bool fbc_download;
 	bool wake_set;
+	bool standard_elf_image;
 	unsigned long irq_flags;
 	u32 mru;
 };

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

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