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Message-ID: <AANLkTi=BYbrVh=oCxZ0xektSxFkg58WJmADS=Ld5f53c@mail.gmail.com>
Date: Tue, 19 Oct 2010 10:56:00 -0400
From: Anderson Lizardo <anderson.lizardo@...nbossa.org>
To: pavan_savoy@...com
Cc: padovan@...fusion.mobi, marcel@...tmann.org,
linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Bluetooth: btwilink driver
On Mon, Oct 18, 2010 at 6:34 PM, <pavan_savoy@...com> wrote:
> diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
> index 02deef4..e0d67dd 100644
> --- a/drivers/bluetooth/Kconfig
> +++ b/drivers/bluetooth/Kconfig
> @@ -219,4 +219,14 @@ config BT_ATH3K
> Say Y here to compile support for "Atheros firmware download driver"
> into the kernel or say M to compile it as module (ath3k).
>
> +config BT_WILINK
> + tristate "BlueZ bluetooth driver for TI ST"
I think this has been mentioned before: "BlueZ" is not used in this
context on the kernel. It is also not consistent with the config name
"BT_WILINK". You can follow the pattern from the other entries and
use:
tristate "Texas Instruments WinLink7 driver"
> + depends on TI_ST
> + help
> + This enables the Bluetooth driver for Texas Instrument's BT/FM/GPS
> + combo devices. This makes use of shared transport line discipline
> + core driver to communicate with the BT core of the combo chip.
> +
> + Say Y here to compile support for Texas Instrument's WiLink7 driver
> + into the kernel or say M to compile it as module.
> endmenu
> [...]
> diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
> new file mode 100644
> index 0000000..e6e2e64
> --- /dev/null
> +++ b/drivers/bluetooth/btwilink.c
> [...]
> +/* Defines number of seconds to wait for reg completion
> + * callback getting called from ST (in case,registration
> + * with ST returns PENDING status)
> + */
I suggest rewriting this comment into:
"Number of seconds to wait for registration completion when ST returns
PENDING status"
> +#define BT_REGISTER_TIMEOUT 6000 /* 6 sec */
> +
> +/**
> + * struct ti_st - BT driver operation structure
> + * @hdev: hci device pointer which binds to bt driver
Just drop "BT" and "bt" here. I think it is clear you are referring to
the Bluetooth driver.
> + * @flags: used locally,to maintain various BT driver status
Suggestion: @flags: driver status flags
(if you can be more specific to which kind of status, it would be even better)
> + * @streg_cbdata: to hold ST registration callback status
You can drop "to hold" here.
> + * @st_write: write function pointer of ST driver
IMHO this description does not add anything to what st_write is for.
> + * @wait_reg_completion - completion sync between ti_st_open
> + * and ti_st_registration_completion_cb.
> + */
> +struct ti_st {
> + struct hci_dev *hdev;
> + char streg_cbdata;
> + long (*st_write) (struct sk_buff *);
> + struct completion wait_reg_completion;
> +};
> +
> +static int reset;
> +
> +/* Increments HCI counters based on pocket ID (cmd,acl,sco) */
> +static inline void ti_st_tx_complete(struct ti_st *hst, int pkt_type)
> +{
> + struct hci_dev *hdev;
> + hdev = hst->hdev;
> +
> + /* Update HCI stat counters */
> + switch (pkt_type) {
> + case HCI_COMMAND_PKT:
> + hdev->stat.cmd_tx++;
> + break;
> +
> + case HCI_ACLDATA_PKT:
> + hdev->stat.acl_tx++;
> + break;
> +
> + case HCI_SCODATA_PKT:
> + hdev->stat.sco_tx++;
> + break;
> + }
> +}
> +
> +/* ------- Interfaces to Shared Transport ------ */
> +
> +/* Called by ST layer to indicate protocol registration completion
> + * status.ti_st_open() function will wait for signal from this
> + * API when st_register() function returns ST_PENDING.
> + */
> +static void st_registration_completion_cb(void *priv_data, char data)
> +{
> + struct ti_st *lhst = (struct ti_st *)priv_data;
Is this explicit cast necessary?
> +
> + /* ti_st_open() function needs value of 'data' to know
> + * the registration status(success/fail),So have a back
> + * up of it.
> + */
Suggestion: /* Save registration status for use in ti_st_open() */
> + lhst->streg_cbdata = data;
> +
> + /* Got a feedback from ST for BT driver registration
> + * request.Wackup ti_st_open() function to continue
> + * it's open operation.
> + */
Too much BT here. If it means "Bluetooth", you don't need to use it
every time. Additionally, I don't get what the above comment means.
> + complete(&lhst->wait_reg_completion);
> +}
> +
> +/* Called by Shared Transport layer when receive data is
> + * available */
> +static long st_receive(void *priv_data, struct sk_buff *skb)
Can this function return "int" instead? It is more common for
functions which return just a error value.
> +{
> + int err;
> + struct ti_st *lhst = (struct ti_st *)priv_data;
Again, is this cast necessary?
> +
> + if (!skb)
> + return -EFAULT;
> +
> + if (!lhst) {
> + kfree_skb(skb);
> + return -EFAULT;
> + }
> +
> + skb->dev = (struct net_device *)lhst->hdev;
> +
> + /* Forward skb to HCI core layer */
> + err = hci_recv_frame(skb);
> + if (err) {
> + kfree_skb(skb);
> + BT_ERR("Unable to push skb to HCI core(%d)", err);
> + return err;
> + }
> +
> + lhst->hdev->stat.byte_rx += skb->len;
Add a blank like here.
> + return 0;
> +}
> +
> +/* ------- Interfaces to HCI layer ------ */
> +/* protocol structure registered with shared transport */
> +static struct st_proto_s ti_st_proto = {
> + .type = ST_BT,
> + .recv = st_receive,
> + .reg_complete_cb = st_registration_completion_cb,
> + .priv_data = NULL,
> +};
> +
> +/* Called from HCI core to initialize the device */
> +static int ti_st_open(struct hci_dev *hdev)
> +{
> + unsigned long timeleft;
> + struct ti_st *hst;
> + int err;
> +
> + BT_DBG("%s %p", hdev->name, hdev);
> +
> + /* provide contexts for callbacks from ST */
> + hst = hdev->driver_data;
> + ti_st_proto.priv_data = hst;
> +
> + err = st_register(&ti_st_proto);
> + if (err == -EINPROGRESS) {
> + /* Prepare wait-for-completion handler data structures.
> + * Needed to syncronize this and st_registration_completion_cb()
> + * functions.
> + */
syncronize -> synchronize
> + init_completion(&hst->wait_reg_completion);
> +
> + /* Reset ST registration callback status flag , this value
> + * will be updated in ti_st_registration_completion_cb()
> + * function whenever it called from ST driver.
> + */
> + hst->streg_cbdata = -EINPROGRESS;
If this field is used solely for holding status values, why not call
it "reg_status" or something like that? "cbdata" is more for opaque
parameters IMHO.
> +
> + /* ST is busy with other protocol registration(may be busy with
> + * firmware download).So,Wait till the registration callback
> + * (passed as a argument to st_register() function) getting
> + * called from ST.
> + */
"ST is busy with either protocol registration or firmware download.
Wait until the registration callback is called."
Is it clearer?
> + BT_DBG(" waiting for reg completion signal from ST");
BT_DBG("Waiting for registration completion signal from ST");
> +
> + timeleft = wait_for_completion_timeout
> + (&hst->wait_reg_completion,
> + msecs_to_jiffies(BT_REGISTER_TIMEOUT));
> + if (!timeleft) {
> + BT_ERR("Timeout(%d sec),didn't get reg "
> + "completion signal from ST",
> + BT_REGISTER_TIMEOUT / 1000);
> + return -ETIMEDOUT;
> + }
> +
> + /* Is ST registration callback called with ERROR value? */
ERROR value -> "error status"
> + if (hst->streg_cbdata != 0) {
> + BT_ERR("ST reg completion CB called with invalid"
> + "status %d", hst->streg_cbdata);
Too much abbreviations here:
reg -> registration
CB -> callback
Also you are truncating the C string wrong here (and maybe in other
places). It will be print as "invalidstatus". Use either
"...invalid<space>" (1st line) or "<space>status..." (2nd line).
> + return -EAGAIN;
> + }
> + err = 0;
> + } else if (err == -EPERM) {
> + BT_ERR("st_register failed %d", err);
> + return err;
> + }
> +
You could assign hst->st_write right here:
hst->st_write = ti_st_proto.write;
And simplify the if/else below to:
if (!hst->st_write) {
BT_ERR(....);
...
}
(i.e. invert the check logic and drop the "!= NULL" case)
> + /* Do we have proper ST write function? */
> + if (ti_st_proto.write != NULL) {
> + /* We need this pointer for sending any Bluetooth pkts */
> + hst->st_write = ti_st_proto.write;
> + } else {
> + BT_ERR("failed to get ST write func pointer");
This error message could be:
BT_ERR("undefined ST write function");
*Although* I think the whole check is in the wrong place. I think this
check should be inside the function which sets ti_st_proto.write.
> +
> + /* Undo registration with ST */
> + err = st_unregister(ST_BT);
> + if (err)
> + BT_ERR("st_unregister failed %d", err);
Suggestion:
BT_ERR("st_unregister() failed with error %d", err);
> +
> + hst->st_write = NULL;
> + return err;
> + }
> +
> + /* Registration with ST layer is completed successfully,
> + * now chip is ready to accept commands from HCI core.
> + * Mark HCI Device flag as RUNNING
> + */
The comment above could be summed as:
/* Registration with ST layer was successful and hardware is ready to
accept commands from HCI core. */
> + set_bit(HCI_RUNNING, &hdev->flags);
Add a blank line here.
> + return err;
> +}
> +
> +/* Close device */
> +static int ti_st_close(struct hci_dev *hdev)
> +{
> + int err;
> + struct ti_st *hst = hdev->driver_data;
> +
> + /* continue to unregister from transport */
> + err = st_unregister(ST_BT);
> + if (err)
> + BT_ERR("st_unregister failed %d", err);
BT_ERR("st_unregister() failed with error %d", err);
> +
> + hst->st_write = NULL;
Add a blank line here.
> + return err;
> +}
> +
> +/* Called from HCI core, Sends frames to Shared Transport */
IMHO the comment above can be dropped (it is too obvious).
> +static int ti_st_send_frame(struct sk_buff *skb)
> +{
> + struct hci_dev *hdev;
> + struct ti_st *hst;
> + long len;
> +
> + if (!skb)
> + return -ENOMEM;
> +
> + hdev = (struct hci_dev *)skb->dev;
> + if (!hdev)
> + return -ENODEV;
> +
> + if (!test_bit(HCI_RUNNING, &hdev->flags))
> + return -EBUSY;
> +
> + hst = (struct ti_st *)hdev->driver_data;
> +
> + /* Prepend skb with frame type */
> + memcpy(skb_push(skb, 1), &bt_cb(skb)->pkt_type, 1);
> +
> + BT_DBG(" %s: type %d len %d", hdev->name, bt_cb(skb)->pkt_type,
> + skb->len);
> +
> + /* Insert skb to shared transport layer's transmit queue.
> + * Freeing skb memory is taken care in shared transport layer,
> + * so don't free skb memory here.
> + */
> + if (!hst->st_write) {
> + kfree_skb(skb);
> + BT_ERR(" Can't write to ST, st_write null?");
Suggestion: BT_ERR("Could not write to ST (st_write is NULL)");
> + return -EAGAIN;
> + }
> +
> + len = hst->st_write(skb);
> + if (len < 0) {
> + kfree_skb(skb);
> + BT_ERR(" ST write failed (%ld)", len);
> + return -EAGAIN;
> + }
> +
> + /* ST accepted our skb. So, Go ahead and do rest */
> + hdev->stat.byte_tx += len;
> + ti_st_tx_complete(hst, bt_cb(skb)->pkt_type);
> +
> + return 0;
> +}
> +
> +static void ti_st_destruct(struct hci_dev *hdev)
> +{
> + if (!hdev)
> + BT_ERR("Destruct called with invalid HCI Device"
> + "(hdev=NULL)");
There is a "return" missing here. Also I don't think this error
message is necessary at all. You could have just:
if (!hdev)
return;
> +
> + BT_DBG("%s", hdev->name);
> +
> + /* free ti_st memory */
> + kfree(hdev->driver_data);
add a blank line here.
> + return;
> +}
> +
> +/* Creates new HCI device */
> +static int ti_st_register_dev(struct ti_st *hst)
> +{
> + int err;
> + struct hci_dev *hdev;
> +
> + /* Initialize and register HCI device */
> + hdev = hci_alloc_dev();
> + if (!hdev)
> + return -ENOMEM;
> +
> + BT_DBG("hdev= %p", hdev);
BT_DBG("hdev %p", hdev);
> +
> + hst->hdev = hdev;
> + hdev->bus = HCI_UART;
> + hdev->driver_data = hst;
> + hdev->open = ti_st_open;
> + hdev->close = ti_st_close;
> + hdev->flush = NULL;
> + hdev->send = ti_st_send_frame;
> + hdev->destruct = ti_st_destruct;
> + hdev->owner = THIS_MODULE;
> +
> + if (reset)
> + set_bit(HCI_QUIRK_NO_RESET, &hdev->quirks);
> +
> + err = hci_register_dev(hdev);
> + if (err < 0) {
> + BT_ERR("Can't register HCI device");
Print the err value on the message above.
> + hci_free_dev(hdev);
> + return err;
> + }
> +
> + BT_DBG(" HCI device registered. hdev= %p", hdev);
Suggestion: BT_DBG("HCI device registered (hdev %p)", hdev);
> + return 0;
> +}
> +
> +
> +static int bt_ti_probe(struct platform_device *pdev)
> +{
> + int err;
> + static struct ti_st *hst;
> +
> + BT_DBG(" Bluetooth Driver Version %s", VERSION);
> +
> + hst = kzalloc(sizeof(struct ti_st), GFP_KERNEL);
> + if (!hst)
> + return -ENOMEM;
> +
> + /* Expose "hciX" device to user space */
> + err = ti_st_register_dev(hst);
> + if (err) {
> + kfree(hst);
> + return err;
> + }
> +
> + dev_set_drvdata(&pdev->dev, hst);
> + return err;
> +}
> +
> +static int bt_ti_remove(struct platform_device *pdev)
> +{
> + struct ti_st *hst;
> +
> + hst = dev_get_drvdata(&pdev->dev);
> + /* Deallocate local resource's memory */
You can invert the hst check:
if (!hst)
return <some_error_code>;
And reduce put the code below outside the if(). Also note that the
current code always returns 0. It should return error for hst == NULL
and hdev == NULL.
> + if (hst) {
> + struct hci_dev *hdev = hst->hdev;
> + if (!hdev) {
> + BT_ERR("Invalid hdev memory");
The error message above is not informative.
> + kfree(hst);
> + } else {
> + ti_st_close(hdev);
> + hci_unregister_dev(hdev);
> + /* Free HCI device memory */
> + hci_free_dev(hdev);
> + }
> + }
> + return 0;
> +}
> +
> +static struct platform_driver btwilink_driver = {
> + .probe = bt_ti_probe,
> + .remove = bt_ti_remove,
> + .driver = {
> + .name = "btwilink",
> + .owner = THIS_MODULE,
> + },
> +};
> +
> +/* ------- Module Init/Exit interfaces ------ */
> +static int __init bt_drv_init(void)
> +{
> + long ret;
> +
> + ret = platform_driver_register(&btwilink_driver);
> + if (ret != 0) {
> + BT_ERR("btwilink platform driver registration failed");
> + return -EPERM;
-EPERM for a registration failure? Looks strange to me.
> + }
> + return 0;
> +}
> +
> +static void __exit bt_drv_exit(void)
> +{
> + platform_driver_unregister(&btwilink_driver);
> +}
> +
> +module_init(bt_drv_init);
> +module_exit(bt_drv_exit);
> +
> +/* ------ Module Info ------ */
> +
> +module_param(reset, bool, 0644);
> +MODULE_PARM_DESC(reset, "Send HCI reset command on initialization");
> +MODULE_AUTHOR("Raja Mani <raja_mani@...com>");
> +MODULE_DESCRIPTION("Bluetooth Driver for TI Shared Transport" VERSION);
> +MODULE_VERSION(VERSION);
> +MODULE_LICENSE("GPL");
> --
> 1.6.5
>
> --
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>
Regards,
--
Anderson Lizardo
OpenBossa Labs - INdT
Manaus - Brazil
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