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SubjectRe: [PATCH v4 2/2] Bluetooth: btusb: Read the supported features of Microsoft vendor extension
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Hi Miao-chen,

> This defines opcode and packet structures of Microsoft vendor extension.
> For now, we add only the HCI_VS_MSFT_Read_Supported_Features command. See
> https://docs.microsoft.com/en-us/windows-hardware/drivers/bluetooth/
> microsoft-defined-bluetooth-hci-commands-and-events#microsoft-defined-
> bluetooth-hci-events for more details.
> Upon initialization of a hci_dev, we issue a
> HCI_VS_MSFT_Read_Supported_Features command to read the supported features
> of Microsoft vendor extension if the opcode of Microsoft vendor extension
> is valid. See https://docs.microsoft.com/en-us/windows-hardware/drivers/
> bluetooth/microsoft-defined-bluetooth-hci-commands-and-events#
> hci_vs_msft_read_supported_features for more details.
> This was verified on a device with Intel ThunderPeak BT controller where
> the Microsoft vendor extension features are 0x000000000000003f.
>
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
>
> Signed-off-by: Miao-chen Chou <mcchou@chromium.org>
> ---
>
> Changes in v4:
> - Move MSFT's do_open() and do_close() from net/bluetooth/hci_core.c to
> net/bluetooth/msft.c.
> - Other than msft opcode, define struct msft_data to host the rest of
> information of Microsoft extension and leave a void* pointing to a
> msft_data in struct hci_dev.
>
> Changes in v3:
> - Introduce msft_vnd_ext_do_open() and msft_vnd_ext_do_close().
>
> Changes in v2:
> - Issue a HCI_VS_MSFT_Read_Supported_Features command with
> __hci_cmd_sync() instead of constructing a request.
>
> include/net/bluetooth/hci_core.h | 1 +
> net/bluetooth/hci_core.c | 5 ++
> net/bluetooth/hci_event.c | 5 ++
> net/bluetooth/msft.c | 126 +++++++++++++++++++++++++++++++
> net/bluetooth/msft.h | 10 +++
> 5 files changed, 147 insertions(+)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index 239cae2d9998..59ddcd3a52cc 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -486,6 +486,7 @@ struct hci_dev {
>
> #if IS_ENABLED(CONFIG_BT_MSFTEXT)
> __u16 msft_opcode;
> + void *msft_data;
> #endif
>
> int (*open)(struct hci_dev *hdev);
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index dbd2ad3a26ed..c38707de767a 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -44,6 +44,7 @@
> #include "hci_debugfs.h"
> #include "smp.h"
> #include "leds.h"
> +#include "msft.h"
>
> static void hci_rx_work(struct work_struct *work);
> static void hci_cmd_work(struct work_struct *work);
> @@ -1563,6 +1564,8 @@ static int hci_dev_do_open(struct hci_dev *hdev)
> hci_dev_test_flag(hdev, HCI_VENDOR_DIAG) && hdev->set_diag)
> ret = hdev->set_diag(hdev, true);
>
> + msft_do_open(hdev);
> +
> clear_bit(HCI_INIT, &hdev->flags);
>
> if (!ret) {
> @@ -1758,6 +1761,8 @@ int hci_dev_do_close(struct hci_dev *hdev)
>
> hci_sock_dev_event(hdev, HCI_DEV_DOWN);
>
> + msft_do_close(hdev);
> +
> if (hdev->flush)
> hdev->flush(hdev);
>
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 20408d386268..42b5871151a6 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -35,6 +35,7 @@
> #include "a2mp.h"
> #include "amp.h"
> #include "smp.h"
> +#include "msft.h"
>
> #define ZERO_KEY "\x00\x00\x00\x00\x00\x00\x00\x00" \
> "\x00\x00\x00\x00\x00\x00\x00\x00"
> @@ -6144,6 +6145,10 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
> hci_num_comp_blocks_evt(hdev, skb);
> break;
>
> + case HCI_EV_VENDOR:
> + msft_vendor_evt(hdev, skb);
> + break;
> +
> default:
> BT_DBG("%s event 0x%2.2x", hdev->name, event);
> break;
> diff --git a/net/bluetooth/msft.c b/net/bluetooth/msft.c
> index 7609932c48ca..f76e4c79556e 100644
> --- a/net/bluetooth/msft.c
> +++ b/net/bluetooth/msft.c
> @@ -6,6 +6,24 @@
>
> #include "msft.h"
>
> +#define MSFT_OP_READ_SUPPORTED_FEATURES 0x00
> +struct msft_cp_read_supported_features {
> + __u8 sub_opcode;
> +} __packed;
> +struct msft_rp_read_supported_features {
> + __u8 status;
> + __u8 sub_opcode;
> + __le64 features;
> + __u8 evt_prefix_len;
> + __u8 evt_prefix[0];
> +} __packed;
> +
> +struct msft_data {
> + __u64 features;
> + __u8 evt_prefix_len;
> + __u8 *evt_prefix;
> +};
> +
> void msft_set_opcode(struct hci_dev *hdev, __u16 opcode)
> {
> hdev->msft_opcode = opcode;
> @@ -14,3 +32,111 @@ void msft_set_opcode(struct hci_dev *hdev, __u16 opcode)
> hdev->msft_opcode);
> }
> EXPORT_SYMBOL(msft_set_opcode);
> +
> +static struct msft_data *read_supported_features(struct hci_dev *hdev)
> +{
> + struct msft_data *msft;

I used a second parameter, but yes, my initial code was totally flawed with the msft_data access.

> + struct msft_cp_read_supported_features cp;
> + struct msft_rp_read_supported_features *rp;
> + struct sk_buff *skb;
> +
> + cp.sub_opcode = MSFT_OP_READ_SUPPORTED_FEATURES;
> +
> + skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
> + HCI_CMD_TIMEOUT);
> + if (IS_ERR(skb)) {
> + bt_dev_err(hdev, "Failed to read MSFT supported features (%ld)",
> + PTR_ERR(skb));
> + return NULL;
> + }
> +
> + if (skb->len < sizeof(*rp)) {
> + bt_dev_err(hdev, "MSFT supported features length mismatch");
> + goto failed;
> + }
> +
> + rp = (struct msft_rp_read_supported_features *)skb->data;
> +
> + if (rp->sub_opcode != MSFT_OP_READ_SUPPORTED_FEATURES)
> + goto failed;
> +
> + msft = kzalloc(sizeof(*msft), GFP_KERNEL);
> + if (!msft)
> + goto failed;
> +
> + if (rp->evt_prefix_len > 0) {
> + msft->evt_prefix = kmemdup(rp->evt_prefix, rp->evt_prefix_len,
> + GFP_KERNEL);
> + if (!msft->evt_prefix)
> + goto failed;
> + }
> +
> + msft->evt_prefix_len = rp->evt_prefix_len;
> + msft->features = __le64_to_cpu(rp->features);
> + kfree_skb(skb);
> +
> + bt_dev_info(hdev, "MSFT supported features %llx", msft->features);
> + return msft;
> +
> +failed:
> + kfree_skb(skb);
> + return NULL;
> +}
> +
> +void msft_do_open(struct hci_dev *hdev)
> +{
> + if (hdev->msft_opcode == HCI_OP_NOP)
> + return;
> +
> + bt_dev_dbg(hdev, "Initialize MSFT extension");
> + hdev->msft_data = read_supported_features(hdev);
> +}
> +
> +void msft_do_close(struct hci_dev *hdev)
> +{
> + struct msft_data *msft = hdev->msft_data;
> +
> + if (!msft)
> + return;
> +
> + bt_dev_dbg(hdev, "Cleanup of MSFT extension");
> +
> + hdev->msft_data = NULL;
> +
> + kfree(msft->evt_prefix);
> + kfree(msft);
> +}
> +
> +int msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb)
> +{

So this was on purpose void. There is no point in returning any feedback from this function. It either handles the event or it doesn’t. The caller function doesn’t care.

> + struct msft_data *msft = hdev->msft_data;
> + u8 event;
> +
> + if (!msft)
> + return -ENOSYS;
> +
> + /* When the extension has defined an event prefix, check that it
> + * matches, and otherwise just return.
> + */
> + if (msft->evt_prefix_len > 0) {
> + if (skb->len < msft->evt_prefix_len)
> + return -ENOSYS;
> +
> + if (memcmp(skb->data, msft->evt_prefix, msft->evt_prefix_len))
> + return -ENOSYS;
> +
> + skb_pull(skb, msft->evt_prefix_len);
> + }
> +
> + /* Every event starts at least with an event code and the rest of
> + * the data is variable and depends on the event code. Returns true
> + */
> + if (skb->len < 1)
> + return -EBADMSG;
> +
> + event = *skb->data;
> + skb_pull(skb, 1);
> +
> + bt_dev_dbg(hdev, "MSFT vendor event %u", event);
> + return 0;
> +}
> diff --git a/net/bluetooth/msft.h b/net/bluetooth/msft.h
> index 7218ea759dde..6a7d0ac6c66c 100644
> --- a/net/bluetooth/msft.h
> +++ b/net/bluetooth/msft.h
> @@ -4,15 +4,25 @@
> #ifndef __MSFT_H
> #define __MSFT_H
>
> +#include <linux/errno.h>
> #include <net/bluetooth/hci_core.h>
>
> #if IS_ENABLED(CONFIG_BT_MSFTEXT)
>
> void msft_set_opcode(struct hci_dev *hdev, __u16 opcode);
> +void msft_do_open(struct hci_dev *hdev);
> +void msft_do_close(struct hci_dev *hdev);
> +int msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb);
>
> #else
>
> static inline void msft_set_opcode(struct hci_dev *hdev, __u16 opcode) {}
> +static inline void msft_do_open(struct hci_dev *hdev) {}
> +static inline void msft_do_close(struct hci_dev *hdev) {}
> +static inline int msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb)
> +{
> + return -ENOSYS;
> +}
>
> #endif

Regards

Marcel

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