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Date: Tue, 31 Mar 2020 08:06:57 +0200
From: Marcel Holtmann <marcel@...tmann.org>
To: Miao-chen Chou <mcchou@...omium.org>
Cc: Bluetooth Kernel Mailing List <linux-bluetooth@...r.kernel.org>,
Alain Michaud <alainm@...omium.org>,
Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Johan Hedberg <johan.hedberg@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] Bluetooth: btusb: Read the supported features of
Microsoft vendor extension
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@...tmann.org>
>>>
>>> Signed-off-by: Miao-chen Chou <mcchou@...omium.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.
> Ack.
>>
>>> + 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.
> I was thinking that if there are two extensions, the vendor events
> should be processed either msft or the other function. Therefore,
> should we use the return value to determine whether to hand skb to the
> other function?
my thinking was that we just hand the vendor events to all functions. Let them deal with the details. I would not over-design this right now. Keep it simple. As long as it is not userspace facing API, we can easily change that when we need it.
Regards
Marcel
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