[PATCH v1 3/3] Bluetooth: btintel_pcie: Route debug traces to WiFi DBGC by default

[Kiran K <kiran.k@intel.com>]

From: Catherine L <catherine.l@intel.com>

Set dbg_output_mode to 0x06 (BTINTEL_PCIE_WIFI_DBGC) by default so
firmware debug traces are forwarded to the WiFi DBGC. In this mode:

  - Host DBGC fragment/data buffers are NOT allocated.
  - Context info publishes dbgc_addr/size as 0.

Add a small helper btintel_pcie_dbg_to_wifi() driven by a cached
dbg_path_cache field in struct btintel_pcie_data, initialized to
BTINTEL_PCIE_WIFI_DBGC in probe.

Signed-off-by: Kiran K <kiran.k@intel.com>
Signed-off-by: Catherine L <catherine.l@intel.com>
---
 drivers/bluetooth/btintel_pcie.c | 43 +++++++++++++++++++++++++++++---
 drivers/bluetooth/btintel_pcie.h | 16 ++++++++++++
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/drivers/bluetooth/btintel_pcie.c b/drivers/bluetooth/btintel_pcie.c
index 93963450ea95..a98edfe81ab8 100644
--- a/drivers/bluetooth/btintel_pcie.c
+++ b/drivers/bluetooth/btintel_pcie.c
@@ -180,6 +180,15 @@ static inline char *btintel_pcie_alivectxt_state2str(u32 alive_intr_ctxt)
 	}
 }
 
+/* Returns true when firmware traces are routed to the WiFi DBGC. In that
+ * mode the host must not allocate DBGC buffers and must not publish their
+ * addresses in the context info.
+ */
+static inline bool btintel_pcie_dbg_to_wifi(struct btintel_pcie_data *data)
+{
+	return data->dbg_path_cache != BTINTEL_PCIE_DRAM;
+}
+
 /* This function initializes the memory for DBGC buffers and formats the
  * DBGC fragment which consists header info and DBGC buffer's LSB, MSB and
  * size as the payload
@@ -1847,6 +1856,15 @@ static void btintel_pcie_coredump_worker(struct work_struct *work)
 	if (!data->hdev)
 		goto out;
 
+	/* When firmware routes debug traces to the WiFi DBGC, no host
+	 * DBGC buffers were allocated, so there is nothing to dump here.
+	 */
+	if (btintel_pcie_dbg_to_wifi(data)) {
+		bt_dev_info(data->hdev,
+			    "Skipping coredump: debug traces routed to WiFi DBGC");
+		goto out;
+	}
+
 	btintel_pcie_dump_traces(data->hdev);
 out:
 	/* Release guard last so a new trigger can run only after this
@@ -2217,9 +2235,18 @@ static void btintel_pcie_init_ci(struct btintel_pcie_data *data,
 	ci->num_urbdq1 = data->rxq.count;
 	ci->urbdq_db_vec = BTINTEL_PCIE_RXQ_NUM;
 
-	ci->dbg_output_mode = 0x01;
-	ci->dbgc_addr = data->dbgc.frag_p_addr;
-	ci->dbgc_size = data->dbgc.frag_size;
+	ci->dbg_output_mode = btintel_pcie_dbg_to_wifi(data) ?
+			      BTINTEL_PCIE_WIFI_DBGC : BTINTEL_PCIE_DRAM;
+	if (btintel_pcie_dbg_to_wifi(data)) {
+		/* Firmware forwards debug traces to the WiFi DBGC, so no
+		 * host DBGC buffer is needed; leave dbgc_addr/size as 0.
+		 */
+		ci->dbgc_addr = 0;
+		ci->dbgc_size = 0;
+	} else {
+		ci->dbgc_addr = data->dbgc.frag_p_addr;
+		ci->dbgc_size = data->dbgc.frag_size;
+	}
 	ci->dbg_preset = 0x00;
 }
 
@@ -2447,7 +2474,14 @@ static int btintel_pcie_alloc(struct btintel_pcie_data *data)
 	v_addr += ci_size;
 
 	/* Setup data buffers for dbgc */
-	err = btintel_pcie_setup_dbgc(data);
+	if (btintel_pcie_dbg_to_wifi(data)) {
+		/* Firmware routes traces to the WiFi DBGC; skip host DBGC
+		 * buffer allocation entirely.
+		 */
+		err = 0;
+	} else {
+		err = btintel_pcie_setup_dbgc(data);
+	}
 	if (err)
 		goto exit_error_txq;
 
@@ -3351,6 +3385,7 @@ static int btintel_pcie_probe(struct pci_dev *pdev,
 
 	data->boot_stage_cache = 0x00;
 	data->img_resp_cache = 0x00;
+	data->dbg_path_cache = BTINTEL_PCIE_WIFI_DBGC;
 	/* FLR can be invoked by echoing to debugfs path, so explicitly
 	 * initialized
 	 */
diff --git a/drivers/bluetooth/btintel_pcie.h b/drivers/bluetooth/btintel_pcie.h
index 5aff1dfa888f..9baa214d9bbe 100644
--- a/drivers/bluetooth/btintel_pcie.h
+++ b/drivers/bluetooth/btintel_pcie.h
@@ -94,6 +94,20 @@
 /* Num of alloc Dbg buff (4) + (LSB(4), MSB(4), Size(4)) for each buffer */
 #define BTINTEL_PCIE_DBGC_FRAG_PAYLOAD_SIZE	196
 
+/* dbg_output_mode values for the context info.
+ *   BTINTEL_PCIE_DRAM: firmware writes traces to host DRAM DBGC buffers.
+ *   BTINTEL_PCIE_WIFI_DBGC: firmware forwards traces to the WiFi DBGC; the
+ *   host does NOT need to allocate DBGC fragment/data buffers and must
+ *   publish dbgc_addr/size as 0 in the context info.
+ *
+ * Encoding of BTINTEL_PCIE_WIFI_DBGC (0x06):
+ *   Bit[0] DBGC O/P  : 0 = SRAM (don't care, DBGI selected)
+ *   Bit[1] DBGC I/P  : 1 = DBGI
+ *   Bits[2:3] DBGI O/P : 01 = WiFi DBGC
+ */
+#define BTINTEL_PCIE_DRAM	0x01
+#define BTINTEL_PCIE_WIFI_DBGC	0x06
+
 /* Causes for the FH register interrupts */
 enum msix_fh_int_causes {
 	BTINTEL_PCIE_MSIX_FH_INT_CAUSES_0	= BIT(0),	/* cause 0 */
@@ -503,6 +517,7 @@ struct btintel_pcie_dump_header {
  * @hw_init_mask: initial unmaksed hw causes
  * @boot_stage_cache: cached value of boot stage register
  * @img_resp_cache: cached value of image response register
+ * @dbg_path_cache: cached debug output routing mode (BT DRAM or WiFi DBGC)
  * @cnvi: CNVi register value
  * @cnvr: CNVr register value
  * @gp0_received: condition for gp0 interrupt
@@ -550,6 +565,7 @@ struct btintel_pcie_data {
 
 	u32	boot_stage_cache;
 	u32	img_resp_cache;
+	u32	dbg_path_cache;
 
 	u32	cnvi;
 	u32	cnvr;
-- 
2.54.0