[PATCH v1] Bluetooth: btintel: read ROM debug registers on FW download failure

[Ravindra <ravindra@intel.com>]

The bootloader records init sequence progress and debug information in
four core debug registers, which helps debugging FW download failures.

Add btintel_get_rom_debug_info() to issue the vendor-specific HCI
command BTINTEL_GET_ROM_DEBUG_INFO (0xfcde) and log these registers, and
invoke it from the error path in btintel_prepare_fw_download_tlv()
before resetting to the bootloader.

Signed-off-by: Ravindra <ravindra@intel.com>
---
 drivers/bluetooth/btintel.c | 40 +++++++++++++++++++++++++++++++++++++
 drivers/bluetooth/btintel.h |  9 +++++++++
 2 files changed, 49 insertions(+)

diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c
index 964d2de30e65..15366a6b54c6 100644
--- a/drivers/bluetooth/btintel.c
+++ b/drivers/bluetooth/btintel.c
@@ -963,6 +963,43 @@ int btintel_send_intel_reset(struct hci_dev *hdev, u32 boot_param)
 }
 EXPORT_SYMBOL_GPL(btintel_send_intel_reset);
 
+static void btintel_get_rom_debug_info(struct hci_dev *hdev)
+{
+	struct btintel_rp_get_rom_debug_info *rom_debug_info;
+	struct sk_buff *skb;
+
+	skb = __hci_cmd_sync(hdev, BTINTEL_GET_ROM_DEBUG_INFO, 0, NULL,
+			     HCI_CMD_TIMEOUT);
+	if (IS_ERR(skb)) {
+		bt_dev_err(hdev, "Failed to send intel get rom debug info command (%ld)",
+			   PTR_ERR(skb));
+		return;
+	}
+
+	if (skb->len != sizeof(*rom_debug_info)) {
+		bt_dev_err(hdev, "Intel get rom debug info command parameters size mismatch");
+		kfree_skb(skb);
+		return;
+	}
+
+	rom_debug_info = (struct btintel_rp_get_rom_debug_info *)skb->data;
+
+	if (rom_debug_info->status) {
+		bt_dev_err(hdev, "Intel get rom debug info command failed (%02x)",
+			   rom_debug_info->status);
+		kfree_skb(skb);
+		return;
+	}
+
+	bt_dev_info(hdev, "Intel get rom debug info: dr0:0x%08x dr1:0x%08x dr2:0x%08x dr3:0x%08x",
+		    le32_to_cpu(rom_debug_info->debug_reg0),
+		    le32_to_cpu(rom_debug_info->debug_reg1),
+		    le32_to_cpu(rom_debug_info->debug_reg2),
+		    le32_to_cpu(rom_debug_info->debug_reg3));
+
+	kfree_skb(skb);
+}
+
 int btintel_read_boot_params(struct hci_dev *hdev,
 			     struct intel_boot_params *params)
 {
@@ -2465,6 +2502,9 @@ static int btintel_prepare_fw_download_tlv(struct hci_dev *hdev,
 			goto done;
 		}
 
+		/* FW download failed, hence collecting rom debug info */
+		btintel_get_rom_debug_info(hdev);
+
 		/* When FW download fails, send Intel Reset to retry
 		 * FW download.
 		 */
diff --git a/drivers/bluetooth/btintel.h b/drivers/bluetooth/btintel.h
index c00f793d9dc8..dedda3e77487 100644
--- a/drivers/bluetooth/btintel.h
+++ b/drivers/bluetooth/btintel.h
@@ -178,6 +178,15 @@ struct hci_ppag_enable_cmd {
 	__le32	ppag_enable_flags;
 } __packed;
 
+#define BTINTEL_GET_ROM_DEBUG_INFO	0xFCDE
+struct btintel_rp_get_rom_debug_info {
+	__u8	status;
+	__le32	debug_reg0;
+	__le32	debug_reg1;
+	__le32	debug_reg2;
+	__le32	debug_reg3;
+} __packed;
+
 #define INTEL_TLV_TYPE_ID		0x01
 
 #define INTEL_TLV_SYSTEM_EXCEPTION	0x00
-- 
2.43.0