[PATCH v5] Bluetooth: btintel: Allow configuring drive strength of BRI

[PATCH v5] Bluetooth: btintel: Allow configuring drive strength of BRI

[Kiran K]

BRI (Bluetooth Radio Interface) traffic from CNVr to CNVi was found causing
cross talk step errors to WiFi. To avoid this potential issue OEM platforms
can replace BRI resistor to adjust the BRI response line drive strength.
During the *setup*, driver reads the drive strength value from uefi
variable and passes it to the controller via vendor specific command with
opcode 0xfc0a.

dmesg:

..
[21.982720] Bluetooth: hci0: Bootloader timestamp 2023.33 buildtype 1 build 45995
[21.984250] Bluetooth: hci0: Found device firmware: intel/ibt-0190-0291-iml.sfi
[21.984255] Bluetooth: hci0: Boot Address: 0x30099000
[21.984256] Bluetooth: hci0: Firmware Version: 160-24.24
[22.011501] Bluetooth: hci0: Waiting for firmware download to complete
[22.011518] Bluetooth: hci0: Firmware loaded in 26624 usecs
[22.011584] Bluetooth: hci0: Waiting for device to boot
[22.013546] Bluetooth: hci0: Malformed MSFT vendor event: 0x02
[22.013552] Bluetooth: hci0: Device booted in 1967 usecs
...
[22.013792] Bluetooth: hci0: dsbr: enable: 0x01 value: 0x0b
...
[22.015027] Bluetooth: hci0: Found device firmware: intel/ibt-0190-0291.sfi
[22.015041] Bluetooth: hci0: Boot Address: 0x10000800
[22.015043] Bluetooth: hci0: Firmware Version: 160-24.24
[22.395821] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[22.395828] Bluetooth: BNEP filters: protocol multicast
...

Signed-off-by: Kiran K <kiran.k@intel.com>
---
 drivers/bluetooth/btintel.c | 124 ++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)

diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c
index 2ebc970e6573..cef74fd1271d 100644
--- a/drivers/bluetooth/btintel.c
+++ b/drivers/bluetooth/btintel.c
@@ -12,6 +12,7 @@
 #include <linux/acpi.h>
 #include <acpi/acpi_bus.h>
 #include <asm/unaligned.h>
+#include <linux/efi.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
@@ -26,6 +27,8 @@
 #define ECDSA_OFFSET		644
 #define ECDSA_HEADER_LEN	320
 
+#define BTINTEL_EFI_DSBR	L"UefiCnvCommonDSBR"
+
 enum {
 	DSM_SET_WDISABLE2_DELAY = 1,
 	DSM_SET_RESET_METHOD = 3,
@@ -2616,6 +2619,120 @@ static u8 btintel_classify_pkt_type(struct hci_dev *hdev, struct sk_buff *skb)
 	return hci_skb_pkt_type(skb);
 }
 
+/*
+ * UefiCnvCommonDSBR UEFI variable provides information from the OEM platforms
+ * if they have replaced the BRI (Bluetooth Radio Interface) resistor to
+ * overcome the potential STEP errors on their designs. Based on the
+ * configauration, bluetooth firmware shall adjust the BRI response line drive
+ * strength. The below structure represents DSBR data.
+ * struct {
+ *	u8 header;
+ *	u32 dsbr;
+ * } __packed;
+ *
+ * header - defines revision number of the structure
+ * dsbr - defines drive strength BRI response
+ *	bit0
+ *		0 - instructs bluetooth firmware to use default values
+ *		1 - instructs bluetooth firmware to override default values
+ *	bit3:1
+ *		Reserved
+ *	bit7:4
+ *		DSBR override values (only if bit0 is set. Default value is 0xF
+ *	bit31:7
+ *		Reserved
+ * Expected values for dsbr field:
+ *	1. 0xF1 - indicates that the resistor on board is 33 Ohm
+ *	2. 0x00 or 0xB1 - indicates that the resistor on board is 10 Ohm
+ *	3. Non existing UEFI variable or invalid (none of the above) - indicates
+ *	   that the resistor on board is 10 Ohm
+ * Even if uefi variable is not present, driver shall send 0xfc0a command to
+ * firmware to use default values.
+ *
+ */
+static int btintel_uefi_get_dsbr(u32 *dsbr_var)
+{
+	struct btintel_dsbr {
+		u8 header;
+		u32 dsbr;
+	} __packed data;
+
+	efi_status_t status;
+	unsigned long data_size = 0;
+	efi_guid_t guid = EFI_GUID(0xe65d8884, 0xd4af, 0x4b20, 0x8d, 0x03,
+				   0x77, 0x2e, 0xcc, 0x3d, 0xa5, 0x31);
+
+	if (!IS_ENABLED(CONFIG_EFI))
+		return -EOPNOTSUPP;
+
+	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
+		return -EOPNOTSUPP;
+
+	status = efi.get_variable(BTINTEL_EFI_DSBR, &guid, NULL, &data_size,
+				  NULL);
+
+	if (status != EFI_BUFFER_TOO_SMALL || !data_size)
+		return -EIO;
+
+	status = efi.get_variable(BTINTEL_EFI_DSBR, &guid, NULL, &data_size,
+				  &data);
+
+	if (status != EFI_SUCCESS)
+		return -ENXIO;
+
+	*dsbr_var = data.dsbr;
+	return 0;
+}
+
+static int btintel_set_dsbr(struct hci_dev *hdev, struct intel_version_tlv *ver)
+{
+	struct btintel_dsbr_cmd {
+		u8 enable;
+		u8 dsbr;
+	} __packed;
+
+	struct btintel_dsbr_cmd cmd;
+	struct sk_buff *skb;
+	u8 status;
+	u32 dsbr;
+	bool apply_dsbr;
+	int err;
+
+	/* DSBR command needs to be sent for BlazarI + B0 step product after
+	 * downloading IML image.
+	 */
+	apply_dsbr = (ver->img_type == BTINTEL_IMG_IML &&
+		((ver->cnvi_top & 0xfff) == BTINTEL_CNVI_BLAZARI) &&
+		INTEL_CNVX_TOP_STEP(ver->cnvi_top) == 0x01);
+
+	if (!apply_dsbr)
+		return 0;
+
+	dsbr = 0;
+	err = btintel_uefi_get_dsbr(&dsbr);
+	if (err < 0)
+		bt_dev_dbg(hdev, "Error reading efi: %ls  (%d)",
+			   BTINTEL_EFI_DSBR, err);
+
+	cmd.enable = dsbr & BIT(0);
+	cmd.dsbr = dsbr >> 4 & 0xF;
+
+	bt_dev_info(hdev, "dsbr: enable: 0x%2.2x value: 0x%2.2x", cmd.enable,
+		    cmd.dsbr);
+
+	skb = __hci_cmd_sync(hdev, 0xfc0a, sizeof(cmd), &cmd,  HCI_CMD_TIMEOUT);
+	if (IS_ERR(skb))
+		return -bt_to_errno(PTR_ERR(skb));
+
+	status = skb->data[0];
+	kfree_skb(skb);
+
+	if (status)
+		return -bt_to_errno(status);
+
+	return 0;
+}
+
 int btintel_bootloader_setup_tlv(struct hci_dev *hdev,
 				 struct intel_version_tlv *ver)
 {
@@ -2650,6 +2767,13 @@ int btintel_bootloader_setup_tlv(struct hci_dev *hdev,
 	if (err)
 		return err;
 
+	/* set drive strength of BRI response */
+	err = btintel_set_dsbr(hdev, ver);
+	if (err) {
+		bt_dev_err(hdev, "Failed to send dsbr command (%d)", err);
+		return err;
+	}
+
 	/* If image type returned is BTINTEL_IMG_IML, then controller supports
 	 * intermediate loader image
 	 */
-- 
2.40.1

RE: [v5] Bluetooth: btintel: Allow configuring drive strength of BRI

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2057 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=872290

---Test result---

Test Summary:
CheckPatch                    PASS      0.61 seconds
GitLint                       FAIL      0.52 seconds
SubjectPrefix                 PASS      0.07 seconds
BuildKernel                   PASS      30.00 seconds
CheckAllWarning               PASS      33.23 seconds
CheckSparse                   PASS      37.82 seconds
CheckSmatch                   PASS      102.73 seconds
BuildKernel32                 PASS      28.72 seconds
TestRunnerSetup               PASS      532.11 seconds
TestRunner_l2cap-tester       PASS      20.19 seconds
TestRunner_iso-tester         PASS      33.94 seconds
TestRunner_bnep-tester        PASS      4.84 seconds
TestRunner_mgmt-tester        PASS      115.72 seconds
TestRunner_rfcomm-tester      PASS      7.58 seconds
TestRunner_sco-tester         PASS      15.06 seconds
TestRunner_ioctl-tester       PASS      7.92 seconds
TestRunner_mesh-tester        PASS      6.03 seconds
TestRunner_smp-tester         PASS      6.95 seconds
TestRunner_userchan-tester    PASS      5.06 seconds
IncrementalBuild              PASS      27.89 seconds

Details
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[v5] Bluetooth: btintel: Allow configuring drive strength of BRI

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
13: B1 Line exceeds max length (81>80): "[21.982720] Bluetooth: hci0: Bootloader timestamp 2023.33 buildtype 1 build 45995"


---
Regards,
Linux Bluetooth

Re: [PATCH v5] Bluetooth: btintel: Allow configuring drive strength of BRI

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Thu, 18 Jul 2024 20:18:04 +0530 you wrote:
> BRI (Bluetooth Radio Interface) traffic from CNVr to CNVi was found causing
> cross talk step errors to WiFi. To avoid this potential issue OEM platforms
> can replace BRI resistor to adjust the BRI response line drive strength.
> During the *setup*, driver reads the drive strength value from uefi
> variable and passes it to the controller via vendor specific command with
> opcode 0xfc0a.
> 
> [...]

Here is the summary with links:
  - [v5] Bluetooth: btintel: Allow configuring drive strength of BRI
    https://git.kernel.org/bluetooth/bluetooth-next/c/c707097a446c

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
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