[PATCH v11 0/7] Bluetooth: btmtk: Add MT7928 support

[PATCH v11 0/7] Bluetooth: btmtk: Add MT7928 support

[Chris Lu]

This patch series adds support for MT7928 (device ID 0x7935) to the
btmtk driver, which requires a new two-stage firmware loading process
with CBMCU firmware.

The series is organized to fix existing issues first, then improve code
quality, and finally add new functionality. Patches have been reordered
in v11 to ensure each commit is independently compilable and functional
(bisectable).

Patch 1 fixes a DMA out-of-bounds access in btmtksdio_tx_packet() where
round_up() alignment causes DMA to read beyond the skb buffer, potentially
leaking kernel memory or triggering IOMMU faults. Also fixes a use-after-free
bug where sdio_hdr pointer becomes invalid after pskb_expand_head() reallocation.

Patch 2 fixes a pre-existing security issue in btmtk_setup_firmware_79xx()
by adding comprehensive firmware size validation to prevent out-of-bounds
memory access with truncated or malicious firmware files.

Patch 3 improves BT firmware logging to provide more useful information
for debugging: adds firmware filename before loading, displays chip ID
as HW version instead of firmware's hwver field, and uses %.16s format
specifier to prevent buffer over-read of the 16-byte datetime field.

Patch 4 fixes a regression introduced in commit 28b7c5a6db74
("Bluetooth: btmtk: Add MT6639 (MT7927) Bluetooth support") where
SDIO devices would incorrectly log "BT HW ver: 0x0000" due to
hardcoded dev_id=0. This also prevents potential MT6639 hardware hangs.

Patch 5 fixes a pre-existing bug in btmtksdio_setup() where
btmtk_fw_get_filename() generates the correct firmware path but is
immediately overwritten by snprintf() with a generic legacy format,
causing newer chips to request incorrect filenames. This patch depends
on Patch 4's dev_id fix.

Patch 6 refactors existing firmware download code by replacing magic
numbers with a descriptive BTMTK_WMT_PKT_* enum, making the packet
sequencing logic clearer.

Patch 7 implements MT7928 firmware download flow, which requires loading
CBMCU firmware before Bluetooth firmware. The CBMCU firmware uses a
two-phase download sequence: Phase 1 downloads the section containing
global descriptor and signature data, Phase 2 downloads the remaining
firmware sections.

Tested on MT7928 hardware with successful firmware loading and
Bluetooth functionality verification.

Changes in v11:
- Patch 1: Fix use-after-free vulnerability in btmtksdio_tx_packet()
  After pskb_expand_head() reallocates the skb buffer, sdio_hdr pointer
  becomes invalid. Fix by reassigning sdio_hdr after reallocation.
  Reported by AI review (Sashiko/Gemini).
- Reorder patches for bisectability:
  * Move Patch 6->3 (firmware logging improvement) to prevent introducing
    buffer over-read risk in intermediate commits
  * Move Patch 3->5 and Patch 4->3 to ensure dev_id fix is applied before
    removing redundant filename override, preventing potential MT6639 hangs

Changes in v10:
- Add Patch 1 to fix DMA out-of-bounds access in btmtksdio_tx_packet()
  Discovered during v9 review - round_up() alignment can cause DMA to read
  beyond skb buffer, potentially leaking kernel memory or triggering IOMMU
  faults. Fix by expanding skb tailroom and zero-filling padding.

Changes in v9:
- Reorder patches to group SDIO fixes together (Patch 3-4)
- Patch 2 (was Patch 1 in v8): Fix firmware size validation in
  btmtk_setup_firmware_79xx()
- Patch 3 (was Patch 1, new in v9): Fix firmware filename override in
  btmtksdio_setup() where btmtk_fw_get_filename() result was incorrectly
  overwritten by snprintf()
- Patch 4 (was Patch 2 in v8): Fix SDIO device logging regression
  SDIO devices were passing hardcoded 0, causing "BT HW ver: 0x0000" log

Changes in v8:
- Add Patch 2 to fix firmware size validation in btmtk_setup_firmware_79xx()
- Add Patch 3 to fix SDIO device logging regression
  SDIO devices were passing hardcoded 0, causing "BT HW ver: 0x0000" log

Changes in v7:
- Patch 6 (was Patch 2): Extend magic number refactoring to
  btmtk_setup_firmware() in addition to btmtk_setup_firmware_79xx() for
  consistency
- Patch 3 (was Patch 2): Fix potential buffer over-read by
  using %.16s format specifier for hdr->datetime which is a 16-byte
  array that may not be null-terminated
- Patch 7 (was Patch 3): Apply same %.16s fix to CBMCU firmware logging

Changes in v6:
- Fix timeout handling in btmtk_cbmcu_patch_status() to return -ETIMEDOUT
  instead of success when polling exhausts retry count
- Add integer overflow protection in btmtk_load_cbmcu_firmware() using
  check_mul_overflow() and check_add_overflow()

Changes in v5:
- Split into three patches: refactoring, logging improvement, and
  new feature
- Add Patch 3 to improve BT firmware logging independently
- Apply same logging improvements to CBMCU firmware in Patch 7

Changes in v4:
- Split into two patches: refactoring and new feature
- Add BTMTK_WMT_PKT_* enum to improve code readability
- Replace magic numbers (0xF0, 0xF1) with descriptive macros

Changes in v3:
- Add firmware size validation with bounds checking
- Improve error messages with context information

Changes in v2:
- Simplified enum usage by consolidating status definitions

Chris Lu (7):
  Bluetooth: btmtksdio: Fix DMA out-of-bounds access in TX path
  Bluetooth: btmtk: Add firmware size validation in
    btmtk_setup_firmware_79xx()
  Bluetooth: btmtk: Improve BT firmware logging
  Bluetooth: btmtksdio: Pass hardware dev_id to mt79xx_setup()
  Bluetooth: btmtksdio: Remove redundant firmware filename override
  Bluetooth: btmtk: Replace magic numbers with WMT packet flag enum
  Bluetooth: btmtk: Add MT7928 support

 drivers/bluetooth/btmtk.c     | 427 +++++++++++++++++++++++++++++++++-
 drivers/bluetooth/btmtk.h     |   9 +
 drivers/bluetooth/btmtksdio.c |  42 +++-
 3 files changed, 459 insertions(+), 19 deletions(-)

--
2.45.2

[PATCH v11 1/7] Bluetooth: btmtksdio: Fix DMA out-of-bounds access in TX path

[Chris Lu]

btmtksdio_tx_packet() aligns transfer size to 256 bytes using
round_up(), but does not ensure the skb buffer has sufficient space,
causing DMA to read beyond the buffer.

Fix by expanding skb tailroom if needed and zero-filling the padding.

Fixes: 9aebfd4a2200 ("Bluetooth: mediatek: add support for MediaTek MT7663S and MT7668S SDIO devices")
Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btmtksdio.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index 5b0fab7b89b5..feda1ea8f256 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -272,6 +272,7 @@ static int btmtksdio_tx_packet(struct btmtksdio_dev *bdev,
 			       struct sk_buff *skb)
 {
 	struct mtkbtsdio_hdr *sdio_hdr;
+	unsigned int padded_len, pad_len;
 	int err;
 
 	/* Make sure that there are enough rooms for SDIO header */
@@ -290,18 +291,42 @@ static int btmtksdio_tx_packet(struct btmtksdio_dev *bdev,
 	sdio_hdr->reserved = cpu_to_le16(0);
 	sdio_hdr->bt_type = hci_skb_pkt_type(skb);
 
+	/* Calculate padded length for block-aligned DMA transfer.
+	 * SDIO requires transfers to be block-aligned (MTK_SDIO_BLOCK_SIZE).
+	 * Pad with zeros to prevent DMA from reading beyond skb buffer.
+	 */
+	padded_len = round_up(skb->len, MTK_SDIO_BLOCK_SIZE);
+	pad_len = padded_len - skb->len;
+
+	if (pad_len > 0) {
+		/* Ensure sufficient tailroom for padding */
+		if (unlikely(skb_tailroom(skb) < pad_len)) {
+			err = pskb_expand_head(skb, 0, pad_len, GFP_ATOMIC);
+			if (err < 0)
+				goto err_skb_pull;
+			/* Reassign sdio_hdr after buffer reallocation */
+			sdio_hdr = (void *)skb->data;
+		}
+
+		/* Zero-fill padding to prevent information disclosure */
+		skb_put_zero(skb, pad_len);
+	}
+
 	clear_bit(BTMTKSDIO_HW_TX_READY, &bdev->tx_state);
-	err = sdio_writesb(bdev->func, MTK_REG_CTDR, skb->data,
-			   round_up(skb->len, MTK_SDIO_BLOCK_SIZE));
+	err = sdio_writesb(bdev->func, MTK_REG_CTDR, skb->data, padded_len);
 	if (err < 0)
-		goto err_skb_pull;
+		goto err_skb_trim;
 
-	bdev->hdev->stat.byte_tx += skb->len;
+	/* Record actual transmitted data (excluding padding) */
+	bdev->hdev->stat.byte_tx += le16_to_cpu(sdio_hdr->len);
 
 	kfree_skb(skb);
 
 	return 0;
 
+err_skb_trim:
+	if (pad_len > 0)
+		skb_trim(skb, skb->len - pad_len);
 err_skb_pull:
 	skb_pull(skb, sizeof(*sdio_hdr));
 
-- 
2.45.2

[PATCH v11 2/7] Bluetooth: btmtk: Add firmware size validation in btmtk_setup_firmware_79xx()

[Chris Lu]

Add firmware size validation to prevent out-of-bounds access when loading
truncated or malicious firmware files.

Add three levels of validation:
1. Minimum size check for header and global descriptor
2. Section map bounds check with integer overflow protection using
   check_mul_overflow() and check_add_overflow()
3. Section data bounds check before accessing each section

This matches the validation approach used in btmtk_load_cbmcu_firmware().

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
Assisted-by: Claude:Sonnet-4.5
---
 drivers/bluetooth/btmtk.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 02a96342e964..3491060b3ae9 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -145,6 +145,7 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 	int err, dlen, i, status;
 	u8 flag, first_block, retry;
 	u32 section_num, dl_size, section_offset;
+	size_t expected_size;
 	u8 cmd[64];
 
 	err = request_firmware(&fw, fwname, &hdev->dev);
@@ -153,12 +154,40 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 		return err;
 	}
 
+	/* Validate minimum firmware size for header and global descriptor */
+	if (fw->size < MTK_FW_ROM_PATCH_HEADER_SIZE + MTK_FW_ROM_PATCH_GD_SIZE) {
+		bt_dev_err(hdev, "Firmware file too small: size=%zu, expected at least %u bytes",
+			   fw->size, MTK_FW_ROM_PATCH_HEADER_SIZE + MTK_FW_ROM_PATCH_GD_SIZE);
+		err = -EINVAL;
+		goto err_release_fw;
+	}
+
 	fw_ptr = fw->data;
 	fw_bin_ptr = fw_ptr;
 	hdr = (struct btmtk_patch_header *)fw_ptr;
 	globaldesc = (struct btmtk_global_desc *)(fw_ptr + MTK_FW_ROM_PATCH_HEADER_SIZE);
 	section_num = le32_to_cpu(globaldesc->section_num);
 
+	/* Check for potential integer overflow in size calculation */
+	if (check_mul_overflow((size_t)MTK_FW_ROM_PATCH_SEC_MAP_SIZE,
+			       (size_t)section_num, &expected_size) ||
+	    check_add_overflow(expected_size,
+			       (size_t)(MTK_FW_ROM_PATCH_HEADER_SIZE +
+					MTK_FW_ROM_PATCH_GD_SIZE),
+			       &expected_size)) {
+		bt_dev_err(hdev, "Firmware size calculation overflow (section_num=%u)",
+			   section_num);
+		err = -EINVAL;
+		goto err_release_fw;
+	}
+
+	if (fw->size < expected_size) {
+		bt_dev_err(hdev, "Firmware truncated: size=%zu, expected=%zu (section_num=%u)",
+			   fw->size, expected_size, section_num);
+		err = -EINVAL;
+		goto err_release_fw;
+	}
+
 	bt_dev_info(hdev, "HW/SW Version: 0x%04x%04x, Build Time: %s",
 		    le16_to_cpu(hdr->hwver), le16_to_cpu(hdr->swver), hdr->datetime);
 
@@ -171,6 +200,16 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 		section_offset = le32_to_cpu(sectionmap->secoffset);
 		dl_size = le32_to_cpu(sectionmap->bin_info_spec.dlsize);
 
+		/* Validate section boundaries to prevent out-of-bounds access */
+		if (dl_size > 0 &&
+		    (section_offset > fw->size ||
+		     dl_size > fw->size - section_offset)) {
+			bt_dev_err(hdev, "Section %d out of bounds: offset=%u, size=%u, fw_size=%zu",
+				   i, section_offset, dl_size, fw->size);
+			err = -EINVAL;
+			goto err_release_fw;
+		}
+
 		/* MT6639: only download sections where dlmode byte0 == 0x01,
 		 * matching the Windows driver behavior which skips WiFi/other
 		 * sections that would cause the chip to hang.
-- 
2.45.2

[PATCH v11 3/7] Bluetooth: btmtk: Improve BT firmware logging

[Chris Lu]

Improve firmware loading log messages to provide more useful information:

- Add firmware filename before loading to help identify which file
  is being loaded
- Display chip ID (dev_id) as HW version instead of firmware's hwver
  field, which provides more meaningful hardware identification
- Use %.16s format specifier for hdr->datetime field to prevent
  potential buffer over-read, as the field is a 16-byte array that
  may not be null-terminated

log output with MT7922
[  212.878783] Bluetooth: hci1: Loading BT firmware: mediatek/BT_RAM_CODE_MT7922_1_1_hdr.bin
[  212.889614] Bluetooth: hci1: BT HW ver: 0x7922, SW ver: 0x008a, Build Time: 20260224103448
[  216.048877] Bluetooth: hci1: Device setup in 3096530 usecs
[  216.048890] Bluetooth: hci1: HCI Enhanced Setup Synchronous Connection command is advertised, but not supported.
[  216.114179] Bluetooth: hci1: AOSP extensions version v1.00
[  216.114220] Bluetooth: hci1: AOSP quality report is supported
[  216.116782] Bluetooth: MGMT ver 1.23

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
Assisted-by: Claude:Sonnet-4.5
---
 drivers/bluetooth/btmtk.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 3491060b3ae9..595e346accc3 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -148,6 +148,8 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 	size_t expected_size;
 	u8 cmd[64];
 
+	bt_dev_info(hdev, "Loading BT firmware: %s", fwname);
+
 	err = request_firmware(&fw, fwname, &hdev->dev);
 	if (err < 0) {
 		bt_dev_err(hdev, "Failed to load firmware file (%d)", err);
@@ -188,8 +190,8 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 		goto err_release_fw;
 	}
 
-	bt_dev_info(hdev, "HW/SW Version: 0x%04x%04x, Build Time: %s",
-		    le16_to_cpu(hdr->hwver), le16_to_cpu(hdr->swver), hdr->datetime);
+	bt_dev_info(hdev, "BT HW ver: 0x%04x, SW ver: 0x%04x, Build Time: %.16s",
+		    dev_id & 0xffff, le16_to_cpu(hdr->swver), hdr->datetime);
 
 	for (i = 0; i < section_num; i++) {
 		first_block = 1;
-- 
2.45.2

[PATCH v11 4/7] Bluetooth: btmtksdio: Pass hardware dev_id to mt79xx_setup()

[Chris Lu]

mt79xx_setup() hardcodes dev_id=0 when calling btmtk_setup_firmware_79xx(),
causing SDIO devices to log incorrect chip ID "BT HW ver: 0x0000" instead
of the actual hardware version read from register 0x70010200.

Pass the hardware dev_id to mt79xx_setup() and forward it to
btmtk_setup_firmware_79xx() to match USB driver behavior and display
correct chip identification.

Fixes: 28b7c5a6db74 ("Bluetooth: btmtk: Add MT6639 (MT7927) Bluetooth support")
Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btmtksdio.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index feda1ea8f256..088fdfb56231 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -901,14 +901,14 @@ static int mt76xx_setup(struct hci_dev *hdev, const char *fwname)
 	return 0;
 }
 
-static int mt79xx_setup(struct hci_dev *hdev, const char *fwname)
+static int mt79xx_setup(struct hci_dev *hdev, const char *fwname, u32 dev_id)
 {
 	struct btmtksdio_dev *bdev = hci_get_drvdata(hdev);
 	struct btmtk_hci_wmt_params wmt_params;
 	u8 param = 0x1;
 	int err;
 
-	err = btmtk_setup_firmware_79xx(hdev, fwname, mtk_hci_wmt_sync, 0);
+	err = btmtk_setup_firmware_79xx(hdev, fwname, mtk_hci_wmt_sync, dev_id);
 	if (err < 0) {
 		bt_dev_err(hdev, "Failed to setup 79xx firmware (%d)", err);
 		return err;
@@ -1167,7 +1167,7 @@ static int btmtksdio_setup(struct hci_dev *hdev)
 		snprintf(fwname, sizeof(fwname),
 			 "mediatek/BT_RAM_CODE_MT%04x_1_%x_hdr.bin",
 			 dev_id & 0xffff, (fw_version & 0xff) + 1);
-		err = mt79xx_setup(hdev, fwname);
+		err = mt79xx_setup(hdev, fwname, dev_id);
 		if (err < 0)
 			return err;
 
-- 
2.45.2

[PATCH v11 5/7] Bluetooth: btmtksdio: Remove redundant firmware filename override

[Chris Lu]

btmtksdio_setup() calls btmtk_fw_get_filename() to generate the correct
firmware filename based on chip ID, then immediately overwrites it with
snprintf() using a generic legacy format. This causes newer chips that
require chip-specific firmware paths (MT6639, MT7925, MT7928) to request
incorrect legacy filenames, leading to firmware load failures.

The USB driver (btmtkusb.c) correctly uses btmtk_fw_get_filename()
without overriding the result. Match that behavior by removing the
redundant snprintf() call.

Fixes: 7f935b21bee4 ("Bluetooth: btmtk: apply the common btmtk_fw_get_filename")
Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btmtksdio.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index 088fdfb56231..4a160d5131f1 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -1164,9 +1164,6 @@ static int btmtksdio_setup(struct hci_dev *hdev)
 		btmtk_fw_get_filename(fwname, sizeof(fwname), dev_id,
 				      fw_version, 0);
 
-		snprintf(fwname, sizeof(fwname),
-			 "mediatek/BT_RAM_CODE_MT%04x_1_%x_hdr.bin",
-			 dev_id & 0xffff, (fw_version & 0xff) + 1);
 		err = mt79xx_setup(hdev, fwname, dev_id);
 		if (err < 0)
 			return err;
-- 
2.45.2

[PATCH v11 6/7] Bluetooth: btmtk: Replace magic numbers with WMT packet flag enum

[Chris Lu]

Add BTMTK_WMT_PKT_* enum to represent WMT download packet sequence flags,
improving code readability. Replace magic numbers (1, 2, 3) in
btmtk_setup_firmware_79xx() and btmtk_setup_firmware() with descriptive
enum values:

- BTMTK_WMT_PKT_START (1): First packet of a sequence
- BTMTK_WMT_PKT_CONTINUE (2): Continuation packet
- BTMTK_WMT_PKT_END (3): Final packet of a sequence

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Assisted-by: Claude:Sonnet-4.5
---
 drivers/bluetooth/btmtk.c | 12 ++++++------
 drivers/bluetooth/btmtk.h |  6 ++++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 595e346accc3..75519765bb49 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -271,12 +271,12 @@ int btmtk_setup_firmware_79xx(struct hci_dev *hdev, const char *fwname,
 			while (dl_size > 0) {
 				dlen = min_t(int, 250, dl_size);
 				if (first_block == 1) {
-					flag = 1;
+					flag = BTMTK_WMT_PKT_START;
 					first_block = 0;
 				} else if (dl_size - dlen <= 0) {
-					flag = 3;
+					flag = BTMTK_WMT_PKT_END;
 				} else {
-					flag = 2;
+					flag = BTMTK_WMT_PKT_CONTINUE;
 				}
 
 				wmt_params.flag = flag;
@@ -355,7 +355,7 @@ int btmtk_setup_firmware(struct hci_dev *hdev, const char *fwname,
 
 	fw_size -= 30;
 	fw_ptr += 30;
-	flag = 1;
+	flag = BTMTK_WMT_PKT_START;
 
 	wmt_params.op = BTMTK_WMT_PATCH_DWNLD;
 	wmt_params.status = NULL;
@@ -365,9 +365,9 @@ int btmtk_setup_firmware(struct hci_dev *hdev, const char *fwname,
 
 		/* Tell device the position in sequence */
 		if (fw_size - dlen <= 0)
-			flag = 3;
+			flag = BTMTK_WMT_PKT_END;
 		else if (fw_size < fw->size - 30)
-			flag = 2;
+			flag = BTMTK_WMT_PKT_CONTINUE;
 
 		wmt_params.flag = flag;
 		wmt_params.dlen = dlen;
diff --git a/drivers/bluetooth/btmtk.h b/drivers/bluetooth/btmtk.h
index c83c24897c95..51c18dde0a80 100644
--- a/drivers/bluetooth/btmtk.h
+++ b/drivers/bluetooth/btmtk.h
@@ -66,6 +66,12 @@ enum {
 	BTMTK_WMT_ON_PROGRESS,
 };
 
+enum {
+	BTMTK_WMT_PKT_START = 1,
+	BTMTK_WMT_PKT_CONTINUE = 2,
+	BTMTK_WMT_PKT_END = 3,
+};
+
 struct btmtk_wmt_hdr {
 	u8	dir;
 	u8	op;
-- 
2.45.2

[PATCH v11 7/7] Bluetooth: btmtk: Add MT7928 support

[Chris Lu]

Add support for MT7928 (internal device ID is MT7935) which requires
additional firmware (CBMCU firmware) loading before Bluetooth firmware.

CBMCU is a new component on MT7928 to handle common part shared across
the combo chip (Wi-Fi/Bluetooth's subsystem), providing a better user
experience through improved coordination between subsystems.

Implement two-phase CBMCU firmware download: Phase 1 loads section with
type 0x5 containing global descriptor, section maps and signature data;
Phase 2 loads remaining firmware sections. Add retry mechanism for
concurrent download protection.

After CBMCU firmware loads successfully, the driver continues to load
corresponding BT firmware based on device ID through fallthrough to
case 0x7922/0x7925.

Use %.16s format specifier for hdr->datetime field in CBMCU firmware
logging to prevent potential buffer over-read, as the field is a 16-byte
array that may not be null-terminated.

The firmware(CBMCU_CODE_MT7935_1_1.bin/BT_RAM_CODE_MT7935_1_1_hdr.bin)
required for MT7928 will be scheduled for upload to linux-firmware at
a later stage.

MT7928 bring-up kernel log:
[ 6931.197167] usb 1-3: New USB device found, idVendor=0e8d, idProduct=7935, bcdDevice= 1.00
[ 6931.197212] usb 1-3: New USB device strings: Mfr=5, Product=6, SerialNumber=7
[ 6931.197237] usb 1-3: Product: Wireless_Device
[ 6931.197258] usb 1-3: Manufacturer: MediaTek Inc.
[ 6931.197279] usb 1-3: SerialNumber: 000000000
[ 6931.213478] Bluetooth: hci1: Loading CBMCU firmware: mediatek/mt7928/CBMCU_CODE_MT7935_1_1.bin
[ 6931.215214] Bluetooth: hci1: CBMCU HW ver: 0x7935, SW ver: 0x0000, Build Time: 20260601T161751+
[ 6931.623962] Bluetooth: hci1: CBMCU firmware download completed
[ 6931.643916] Bluetooth: hci1: Loading BT firmware: mediatek/mt7928/BT_RAM_CODE_MT7935_1_1_hdr.bin
[ 6931.650467] Bluetooth: hci1: BT HW ver: 0x7935, SW ver: 0x0000, Build Time: 20260527000816
[ 6935.039790] Bluetooth: hci1: Device setup in 3369644 usecs
[ 6935.039833] Bluetooth: hci1: HCI Enhanced Setup Synchronous Connection command is advertised, but not supported.
[ 6935.160654] Bluetooth: hci1: AOSP extensions version v2.00
[ 6935.160710] Bluetooth: hci1: AOSP quality report is supported
[ 6935.162954] Bluetooth: MGMT ver 1.23

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Sean Wang <sean.wang@mediatek.com>
Assisted-by: Claude:Sonnet-4.5
---
 drivers/bluetooth/btmtk.c | 370 +++++++++++++++++++++++++++++++++++++-
 drivers/bluetooth/btmtk.h |   3 +
 2 files changed, 372 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 75519765bb49..50d3d69f91d3 100644
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -21,6 +21,12 @@
 #define MTK_FW_ROM_PATCH_SEC_MAP_SIZE	64
 #define MTK_SEC_MAP_COMMON_SIZE	12
 #define MTK_SEC_MAP_NEED_SEND_SIZE	52
+#define MTK_SEC_MAP_LENGTH_SIZE	4
+#define MTK_SEC_CBMCU_DESC	0x5
+
+/* CBMCU WMT command flags */
+#define BTMTK_CBMCU_FLAG_QUERY_STATUS	0xF0
+#define BTMTK_CBMCU_FLAG_ENABLE_PATCH	0xF1
 
 /* It is for mt79xx iso data transmission setting */
 #define MTK_ISO_THRESHOLD	264
@@ -120,6 +126,11 @@ void btmtk_fw_get_filename(char *buf, size_t size, u32 dev_id, u32 fw_ver,
 		snprintf(buf, size,
 			 "mediatek/mt%04x/BT_RAM_CODE_MT%04x_1_%x_hdr.bin",
 			 dev_id & 0xffff, dev_id & 0xffff, (fw_ver & 0xff) + 1);
+	/* MT7928 */
+	else if (dev_id == 0x7935)
+		snprintf(buf, size,
+			 "mediatek/mt7928/BT_RAM_CODE_MT%04x_1_1_hdr.bin",
+			 dev_id & 0xffff);
 	else if (dev_id == 0x7961 && fw_flavor)
 		snprintf(buf, size,
 			 "mediatek/BT_RAM_CODE_MT%04x_1a_%x_hdr.bin",
@@ -775,6 +786,7 @@ static int btmtk_usb_hci_wmt_sync(struct hci_dev *hdev,
 			status = BTMTK_WMT_ON_UNDONE;
 		break;
 	case BTMTK_WMT_PATCH_DWNLD:
+	case BTMTK_WMT_CBMCU_DWNLD:
 		if (wmt_evt->whdr.flag == 2)
 			status = BTMTK_WMT_PATCH_DONE;
 		else if (wmt_evt->whdr.flag == 1)
@@ -911,6 +923,351 @@ static u32 btmtk_usb_reset_done(struct hci_dev *hdev)
 	return val & MTK_BT_RST_DONE;
 }
 
+static int btmtk_cbmcu_patch_status(struct hci_dev *hdev,
+				    wmt_cmd_sync_func_t wmt_cmd_sync,
+				    u8 *patch_status)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	int status, err, retry = 20;
+
+	do {
+		wmt_params.op = BTMTK_WMT_CBMCU_DWNLD;
+		wmt_params.flag = BTMTK_CBMCU_FLAG_QUERY_STATUS;
+		wmt_params.dlen = 0;
+		wmt_params.data = NULL;
+		wmt_params.status = &status;
+
+		err = wmt_cmd_sync(hdev, &wmt_params);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to query CBMCU patch status (%d)", err);
+			return err;
+		}
+
+		*patch_status = (u8)status;
+
+		if (*patch_status == BTMTK_WMT_PATCH_PROGRESS) {
+			msleep(100);
+			retry--;
+		} else {
+			break;
+		}
+	} while (retry > 0);
+
+	if (*patch_status == BTMTK_WMT_PATCH_PROGRESS) {
+		bt_dev_err(hdev, "CBMCU patch status query timeout");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int btmtk_query_cbmcu_section(struct hci_dev *hdev,
+				     wmt_cmd_sync_func_t wmt_cmd_sync,
+				     u8 cbmcu_type,
+				     const u8 *section_map,
+				     u32 cert_len)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	u8 cmd[64];
+	int status, err;
+
+	cmd[0] = 0;
+	cmd[1] = cbmcu_type;
+
+	if (cbmcu_type == 0)
+		put_unaligned_le32(cert_len, &cmd[2]);
+	else
+		memcpy(&cmd[2], section_map, MTK_SEC_MAP_NEED_SEND_SIZE);
+
+	wmt_params.op = BTMTK_WMT_CBMCU_DWNLD;
+	wmt_params.flag = 0;
+	wmt_params.dlen = cbmcu_type ?
+		MTK_SEC_MAP_NEED_SEND_SIZE + 2 :
+		MTK_SEC_MAP_LENGTH_SIZE + 2;
+	wmt_params.data = cmd;
+	wmt_params.status = &status;
+
+	err = wmt_cmd_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to query CBMCU section (%d)", err);
+		return err;
+	}
+
+	/* Query should return UNDONE status for successful section query */
+	if (status != BTMTK_WMT_PATCH_UNDONE) {
+		bt_dev_err(hdev, "CBMCU section query status error (%d)", status);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int btmtk_download_cbmcu_section(struct hci_dev *hdev,
+					wmt_cmd_sync_func_t wmt_cmd_sync,
+					const u8 *fw_data,
+					u32 dl_size)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	u32 sent_len, total_size = dl_size;
+	int err;
+
+	wmt_params.op = BTMTK_WMT_CBMCU_DWNLD;
+	wmt_params.status = NULL;
+
+	while (dl_size > 0) {
+		sent_len = min_t(u32, 250, dl_size);
+
+		if (dl_size == total_size)
+			wmt_params.flag = BTMTK_WMT_PKT_START;
+		else if (dl_size == sent_len)
+			wmt_params.flag = BTMTK_WMT_PKT_END;
+		else
+			wmt_params.flag = BTMTK_WMT_PKT_CONTINUE;
+
+		wmt_params.dlen = sent_len;
+		wmt_params.data = fw_data;
+
+		err = wmt_cmd_sync(hdev, &wmt_params);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to send CBMCU section data (%d)", err);
+			return err;
+		}
+
+		dl_size -= sent_len;
+		fw_data += sent_len;
+	}
+
+	return 0;
+}
+
+static int btmtk_enable_cbmcu_patch(struct hci_dev *hdev,
+				    wmt_cmd_sync_func_t wmt_cmd_sync)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	int err;
+
+	wmt_params.op = BTMTK_WMT_CBMCU_DWNLD;
+	wmt_params.flag = BTMTK_CBMCU_FLAG_ENABLE_PATCH;
+	wmt_params.dlen = 0;
+	wmt_params.data = NULL;
+	wmt_params.status = NULL;
+
+	err = wmt_cmd_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to enable CBMCU patch (%d)", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static int btmtk_load_cbmcu_firmware(struct hci_dev *hdev,
+				     const char *fwname,
+				     wmt_cmd_sync_func_t wmt_cmd_sync,
+				     u32 dev_id)
+{
+	struct btmtk_patch_header *hdr;
+	struct btmtk_global_desc *globaldesc;
+	struct btmtk_section_map *sectionmap;
+	const struct firmware *fw;
+	const u8 *fw_ptr;
+	u8 *cert_buf = NULL;
+	u32 section_num, section_offset, dl_size, cert_len;
+	size_t expected_size;
+	int i, err;
+
+	err = request_firmware(&fw, fwname, &hdev->dev);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to load CBMCU firmware file %s (%d)",
+			   fwname, err);
+		return err;
+	}
+
+	if (fw->size < MTK_FW_ROM_PATCH_HEADER_SIZE + MTK_FW_ROM_PATCH_GD_SIZE) {
+		bt_dev_err(hdev, "CBMCU firmware too small: size=%zu, min=%u",
+			   fw->size,
+			   MTK_FW_ROM_PATCH_HEADER_SIZE + MTK_FW_ROM_PATCH_GD_SIZE);
+		err = -EINVAL;
+		goto err_release_fw;
+	}
+
+	fw_ptr = fw->data;
+	hdr = (struct btmtk_patch_header *)fw_ptr;
+	globaldesc = (struct btmtk_global_desc *)(fw_ptr + MTK_FW_ROM_PATCH_HEADER_SIZE);
+	section_num = le32_to_cpu(globaldesc->section_num);
+
+	/* Check for potential integer overflow in size calculation */
+	if (check_mul_overflow((size_t)MTK_FW_ROM_PATCH_SEC_MAP_SIZE,
+			       (size_t)section_num, &expected_size) ||
+	    check_add_overflow(expected_size,
+			       (size_t)(MTK_FW_ROM_PATCH_HEADER_SIZE +
+					MTK_FW_ROM_PATCH_GD_SIZE),
+			       &expected_size)) {
+		bt_dev_err(hdev, "CBMCU firmware size calculation overflow (section_num=%u)",
+			   section_num);
+		err = -EINVAL;
+		goto err_release_fw;
+	}
+
+	if (fw->size < expected_size) {
+		bt_dev_err(hdev, "CBMCU firmware truncated: size=%zu, expected=%zu (section_num=%u)",
+			   fw->size, expected_size, section_num);
+		err = -EINVAL;
+		goto err_release_fw;
+	}
+
+	bt_dev_info(hdev, "CBMCU HW ver: 0x%04x, SW ver: 0x%04x, Build Time: %.16s",
+		    dev_id & 0xffff, le16_to_cpu(hdr->swver), hdr->datetime);
+
+	/* Phase 1: Download section type MTK_SEC_CBMCU_DESC */
+	for (i = 0; i < section_num; i++) {
+		sectionmap = (struct btmtk_section_map *)
+			(fw_ptr + MTK_FW_ROM_PATCH_HEADER_SIZE +
+			 MTK_FW_ROM_PATCH_GD_SIZE +
+			 MTK_FW_ROM_PATCH_SEC_MAP_SIZE * i);
+
+		/* Only process MTK_SEC_CBMCU_DESC section in Phase 1 */
+		if ((le32_to_cpu(sectionmap->sectype) & 0xFFFF) != MTK_SEC_CBMCU_DESC)
+			continue;
+
+		section_offset = le32_to_cpu(sectionmap->secoffset);
+		dl_size = le32_to_cpu(sectionmap->secsize);
+
+		if (dl_size == 0)
+			continue;
+
+		if (section_offset > fw->size ||
+		    dl_size > fw->size - section_offset) {
+			bt_dev_err(hdev, "CBMCU Phase 1 section out of bounds");
+			err = -EINVAL;
+			goto err_release_fw;
+		}
+
+		cert_len = MTK_FW_ROM_PATCH_GD_SIZE +
+			   MTK_FW_ROM_PATCH_SEC_MAP_SIZE * section_num +
+			   dl_size;
+
+		/* Query cbmcu section */
+		err = btmtk_query_cbmcu_section(hdev, wmt_cmd_sync, 0, NULL,
+						cert_len);
+		if (err < 0)
+			goto err_release_fw;
+
+		cert_buf = kmalloc(cert_len, GFP_KERNEL);
+		if (!cert_buf) {
+			err = -ENOMEM;
+			goto err_release_fw;
+		}
+
+		/* Copy Global Descriptor + All Section Maps */
+		memcpy(cert_buf,
+		       fw_ptr + MTK_FW_ROM_PATCH_HEADER_SIZE,
+		       MTK_FW_ROM_PATCH_GD_SIZE + MTK_FW_ROM_PATCH_SEC_MAP_SIZE * section_num);
+
+		/* Copy Phase 1 section data */
+		memcpy(cert_buf + MTK_FW_ROM_PATCH_GD_SIZE +
+		       MTK_FW_ROM_PATCH_SEC_MAP_SIZE * section_num,
+		       fw_ptr + section_offset,
+		       dl_size);
+
+		/* Download Phase 1 section */
+		err = btmtk_download_cbmcu_section(hdev, wmt_cmd_sync,
+						   cert_buf, cert_len);
+		kfree(cert_buf);
+		cert_buf = NULL;
+
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to download CBMCU Phase 1 section (%d)", err);
+			goto err_release_fw;
+		}
+
+		break;
+	}
+
+	/* Phase 2: Download other sections (type != MTK_SEC_CBMCU_DESC) */
+	for (i = 0; i < section_num; i++) {
+		sectionmap = (struct btmtk_section_map *)
+			(fw_ptr + MTK_FW_ROM_PATCH_HEADER_SIZE +
+			 MTK_FW_ROM_PATCH_GD_SIZE +
+			 MTK_FW_ROM_PATCH_SEC_MAP_SIZE * i);
+
+		/* Skip MTK_SEC_CBMCU_DESC section in Phase 2 */
+		if ((le32_to_cpu(sectionmap->sectype) & 0xFFFF) == MTK_SEC_CBMCU_DESC)
+			continue;
+
+		section_offset = le32_to_cpu(sectionmap->secoffset);
+		dl_size = le32_to_cpu(sectionmap->bin_info_spec.dlsize);
+
+		if (dl_size == 0)
+			continue;
+
+		if (section_offset > fw->size ||
+		    dl_size > fw->size - section_offset) {
+			bt_dev_err(hdev, "CBMCU Phase 2 section %d out of bounds", i);
+			err = -EINVAL;
+			goto err_release_fw;
+		}
+
+		/* Query cbmcu section */
+		err = btmtk_query_cbmcu_section(hdev, wmt_cmd_sync, 1,
+						(u8 *)&sectionmap->bin_info_spec,
+						0);
+		if (err < 0)
+			goto err_release_fw;
+
+		/* Download section data */
+		err = btmtk_download_cbmcu_section(hdev, wmt_cmd_sync,
+						   fw_ptr + section_offset,
+						   dl_size);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to download CBMCU section %d (%d)", i, err);
+			goto err_release_fw;
+		}
+	}
+
+	bt_dev_info(hdev, "CBMCU firmware download completed");
+
+err_release_fw:
+	release_firmware(fw);
+	return err;
+}
+
+static int btmtk_setup_cbmcu_firmware(struct hci_dev *hdev,
+				      wmt_cmd_sync_func_t wmt_cmd_sync,
+				      u32 dev_id)
+{
+	char cbmcu_fwname[64];
+	u8 patch_status;
+	int err;
+
+	err = btmtk_cbmcu_patch_status(hdev, wmt_cmd_sync, &patch_status);
+	if (err < 0)
+		return err;
+
+	bt_dev_dbg(hdev, "CBMCU patch status: 0x%02x", patch_status);
+
+	if (patch_status != BTMTK_WMT_PATCH_UNDONE)
+		return 0;
+
+	snprintf(cbmcu_fwname, sizeof(cbmcu_fwname),
+		 "mediatek/mt7928/CBMCU_CODE_MT%04x_1_1.bin",
+		 dev_id & 0xffff);
+
+	bt_dev_info(hdev, "Loading CBMCU firmware: %s", cbmcu_fwname);
+
+	err = btmtk_load_cbmcu_firmware(hdev, cbmcu_fwname, wmt_cmd_sync, dev_id);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to download CBMCU firmware (%d)", err);
+		return err;
+	}
+
+	err = btmtk_enable_cbmcu_patch(hdev, wmt_cmd_sync);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
 int btmtk_usb_subsys_reset(struct hci_dev *hdev, u32 dev_id)
 {
 	u32 val;
@@ -935,7 +1292,7 @@ int btmtk_usb_subsys_reset(struct hci_dev *hdev, u32 dev_id)
 		if (err < 0)
 			return err;
 		msleep(100);
-	} else if (dev_id == 0x7925 || dev_id == 0x6639) {
+	} else if (dev_id == 0x7925 || dev_id == 0x6639 || dev_id == 0x7935) {
 		err = btmtk_usb_uhw_reg_read(hdev, MTK_BT_RESET_REG_CONNV3, &val);
 		if (err < 0)
 			return err;
@@ -1420,6 +1777,15 @@ int btmtk_usb_setup(struct hci_dev *hdev)
 	case 0x7668:
 		fwname = FIRMWARE_MT7668;
 		break;
+	case 0x7935:
+		/* Requires CBMCU firmware before BT firmware */
+		err = btmtk_setup_cbmcu_firmware(hdev, btmtk_usb_hci_wmt_sync,
+						 dev_id);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to set up CBMCU firmware (%d)", err);
+			return err;
+		}
+		fallthrough;
 	case 0x7922:
 	case 0x7925:
 		/*
@@ -1637,3 +2003,5 @@ MODULE_FIRMWARE(FIRMWARE_MT7922);
 MODULE_FIRMWARE(FIRMWARE_MT7961);
 MODULE_FIRMWARE(FIRMWARE_MT7925);
 MODULE_FIRMWARE(FIRMWARE_MT7927);
+MODULE_FIRMWARE(FIRMWARE_MT7928);
+MODULE_FIRMWARE(FIRMWARE_MT7928_CBMCU);
diff --git a/drivers/bluetooth/btmtk.h b/drivers/bluetooth/btmtk.h
index 51c18dde0a80..5fe4964b031b 100644
--- a/drivers/bluetooth/btmtk.h
+++ b/drivers/bluetooth/btmtk.h
@@ -9,6 +9,8 @@
 #define FIRMWARE_MT7961		"mediatek/BT_RAM_CODE_MT7961_1_2_hdr.bin"
 #define FIRMWARE_MT7925		"mediatek/mt7925/BT_RAM_CODE_MT7925_1_1_hdr.bin"
 #define FIRMWARE_MT7927		"mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin"
+#define FIRMWARE_MT7928		"mediatek/mt7928/BT_RAM_CODE_MT7935_1_1_hdr.bin"
+#define FIRMWARE_MT7928_CBMCU	"mediatek/mt7928/CBMCU_CODE_MT7935_1_1.bin"
 
 #define HCI_EV_WMT 0xe4
 #define HCI_WMT_MAX_EVENT_SIZE		64
@@ -54,6 +56,7 @@ enum {
 	BTMTK_WMT_RST = 0x7,
 	BTMTK_WMT_REGISTER = 0x8,
 	BTMTK_WMT_SEMAPHORE = 0x17,
+	BTMTK_WMT_CBMCU_DWNLD = 0x58,
 };
 
 enum {
-- 
2.45.2