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    SubjectRe: [PATCH v5] Bluetooth: btwilink driver
    From
    Gustavo,

    On Wed, Nov 17, 2010 at 4:24 AM, Gustavo F. Padovan
    <padovan@profusion.mobi> wrote:
    > Hi Pavan,
    >
    > * pavan_savoy@ti.com <pavan_savoy@ti.com> [2010-11-10 08:07:26 -0500]:
    >
    >> From: Pavan Savoy <pavan_savoy@ti.com>
    >>
    >> Marcel,
    >>
    >> Thanks for the comments...
    >> This patch contains,
    >> v5 comments :-
    >> declaration and assiging of variables and private data fixed up.
    >> proper casting.
    >> removed redundant un-necessary checks in send_frame.
    >> HCI_RUNNING fixes in terms of test_and_set/clear bit instead of set and
    >> clear.
    >> removed redundant checks for hdev, skb being NULL.
    >> removed module_param of reset, also WiLink don't need HCI_RESET anyways.
    >> removed ti_st_register_dev function and functionality moved to _probe.
    >> module_init/exit function names fixed up.
    >>
    >> stat byte counter increments and tx_complete is similar to hci_ldisc.
    >> Also I have not implemented the flush routine, since the functionality
    >> which needs to be done in flush routine is done in the underlying driver
    >> which is the shared transport driver and moreover the btwilink driver by
    >> itself doesn't maintains queue or data relevant to transport, so nothing
    >> to do.
    >>
    >> And Yes, I have verified this driver with multiple up/down reset on
    >> hci0.
    >> Also I generally test a2dp/ftp to verify large data transfers.
    >
    > Before re-submit a patch you have to fix all issues reported by the
    > reviewer or reply to patch thread why do you think you right and don't
    > want to change that. That is not happening with your patches, you are
    > not fixing all the stuff before re-submiting and it is not the first
    > time.  If you do it right we can review it fast and your code goes
    > earlier to mainline.
    > You should also answer the questions first  like "Where is the
    > ti_st_proto.write coming from?" You just ignored the
    > review and submitted a new patch.

    This is the reason, I tend to keep the patch comments in the mail.
    I have mentioned here the
    1. comments I have taken care of,
    2. few comments which I don't understand why it is like that and which
    are not taken care of.

    Also the question on ti_st_proto.write, I have answered it twice in
    mail, once to you and once to marcel, for more clarity I have even
    added it in the code comments, Please have a look @ line
    >> + /* ti_st_proto.write is filled up by the underlying shared
    >> + * transport driver upon registration
    >> + */
    As to why this function is not EXPORT_SYMBOL and just an function
    pointer, Yes I had it as function pointer - But since something like
    _read is callback from the protocol driver perspective - to maintain
    uniformity I have this as function pointer.
    (Note: comments to other drivers which are based on ST driver intended
    read/write to be pointers which register/unregister to be EXPORTs).

    Ok, apart from this there was an open question as why I am checking
    for only 2 error conditions, it is because the underlying driver only
    can send those 2 errors and nothing else (st_register has few errors
    it can throw...)

    I understand my problem with test_and_set_bit, I will correct it, But
    I still feel I do nothing critical before test/set so as to return
    error if already opened - But will correct it and do it at the
    beginning ...

    Also what should I be doing regarding the deferred stats update? I
    checked up hci_ldisc which is what this code is pretty much based on,
    and see that it does pretty much the same thing ....
    hci_uart_tx_complete is called after the tty->ops->write correct ?

    I also now understand the issue in module_init regarding the
    platform_driver registration and will fix that.

    Thanks,
    Pavan
    >>
    >> v4 comments :-
    >> module init now returns what platform_driver_register returns.
    >> type casting of void* private data has been removed
    >>
    >> v3 comments :-
    >> Lizardo,
    >> I have taken care of most of the comments you had.
    >> Have re-wrote some of the code commenting you've mentioned.
    >> Thanks for the comments,
    >>
    >> The other few like -EPERM for platform driver registration is to keep
    >> it similar to other drivers, type casting is maintained just to feel safe
    >> and have style similar to other drivers.
    >> BT_WILINK in Kconfig is similar to BT_MRVL.
    >> I hope those aren't too critical.
    >>
    >> -- patch description --
    >>
    >> This is the bluetooth protocol driver for the TI WiLink7 chipsets.
    >> Texas Instrument's WiLink chipsets combine wireless technologies
    >> like BT, FM, GPS and WLAN onto a single chip.
    >>
    >> This Bluetooth driver works on top of the TI_ST shared transport
    >> line discipline driver which also allows other drivers like
    >> FM V4L2 and GPS character driver to make use of the same UART interface.
    >>
    >> Kconfig and Makefile modifications to enable the Bluetooth
    >> driver for Texas Instrument's WiLink 7 chipset.
    >>
    >> Signed-off-by: Pavan Savoy <pavan_savoy@ti.com>
    >> ---
    >>  drivers/bluetooth/Kconfig    |   10 +
    >>  drivers/bluetooth/Makefile   |    1 +
    >>  drivers/bluetooth/btwilink.c |  379 ++++++++++++++++++++++++++++++++++++++++++
    >>  3 files changed, 390 insertions(+), 0 deletions(-)
    >>  create mode 100644 drivers/bluetooth/btwilink.c
    >>
    >> diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
    >> index 02deef4..8e0de9a 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 "Texas Instruments WiLink7 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/Makefile b/drivers/bluetooth/Makefile
    >> index 71bdf13..f4460f4 100644
    >> --- a/drivers/bluetooth/Makefile
    >> +++ b/drivers/bluetooth/Makefile
    >> @@ -18,6 +18,7 @@ obj-$(CONFIG_BT_HCIBTSDIO)  += btsdio.o
    >>  obj-$(CONFIG_BT_ATH3K)               += ath3k.o
    >>  obj-$(CONFIG_BT_MRVL)                += btmrvl.o
    >>  obj-$(CONFIG_BT_MRVL_SDIO)   += btmrvl_sdio.o
    >> +obj-$(CONFIG_BT_WILINK)              += btwilink.o
    >>
    >>  btmrvl-y                     := btmrvl_main.o
    >>  btmrvl-$(CONFIG_DEBUG_FS)    += btmrvl_debugfs.o
    >> diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
    >> new file mode 100644
    >> index 0000000..1b1c4bc
    >> --- /dev/null
    >> +++ b/drivers/bluetooth/btwilink.c
    >> @@ -0,0 +1,379 @@
    >> +/*
    >> + *  Texas Instrument's Bluetooth Driver For Shared Transport.
    >> + *
    >> + *  Bluetooth Driver acts as interface between HCI core and
    >> + *  TI Shared Transport Layer.
    >> + *
    >> + *  Copyright (C) 2009-2010 Texas Instruments
    >> + *  Author: Raja Mani <raja_mani@ti.com>
    >> + *   Pavan Savoy <pavan_savoy@ti.com>
    >> + *
    >> + *  This program is free software; you can redistribute it and/or modify
    >> + *  it under the terms of the GNU General Public License version 2 as
    >> + *  published by the Free Software Foundation.
    >> + *
    >> + *  This program is distributed in the hope that it will be useful,
    >> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
    >> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    >> + *  GNU General Public License for more details.
    >> + *
    >> + *  You should have received a copy of the GNU General Public License
    >> + *  along with this program; if not, write to the Free Software
    >> + *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    >> + *
    >> + */
    >> +
    >> +#include <linux/platform_device.h>
    >> +#include <net/bluetooth/bluetooth.h>
    >> +#include <net/bluetooth/hci_core.h>
    >> +
    >> +#include <linux/ti_wilink_st.h>
    >> +
    >> +/* Bluetooth Driver Version */
    >> +#define VERSION               "1.0"
    >> +
    >> +/* Number of seconds to wait for registration completion
    >> + * when ST returns PENDING status.
    >> + */
    >> +#define BT_REGISTER_TIMEOUT   6000   /* 6 sec */
    >> +
    >> +/**
    >> + * struct ti_st - driver operation structure
    >> + * @hdev: hci device pointer which binds to bt driver
    >> + * @reg_status: ST registration callback status
    >> + * @st_write: write function provided by the ST driver
    >> + *   to be used by the driver during send_frame.
    >> + * @wait_reg_completion - completion sync between ti_st_open
    >> + *   and ti_st_registration_completion_cb.
    >> + */
    >> +struct ti_st {
    >> +     struct hci_dev *hdev;
    >> +     char reg_status;
    >> +     long (*st_write) (struct sk_buff *);
    >> +     struct completion wait_reg_completion;
    >> +};
    >> +
    >> +/* 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 = 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 = priv_data;
    >> +
    >> +     /* Save registration status for use in ti_st_open() */
    >> +     lhst->reg_status = data;
    >> +     /* complete the wait in ti_st_open() */
    >> +     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)
    >> +{
    >> +     struct ti_st *lhst = priv_data;
    >> +     int err;
    >> +
    >> +     if (!skb)
    >> +             return -EFAULT;
    >> +
    >> +     if (!lhst) {
    >> +             kfree_skb(skb);
    >> +             return -EFAULT;
    >> +     }
    >> +
    >> +     skb->dev = (void *) lhst->hdev;
    >> +
    >> +     /* Forward skb to HCI core layer */
    >> +     err = hci_recv_frame(skb);
    >> +     if (err < 0) {
    >> +             BT_ERR("Unable to push skb to HCI core(%d)", err);
    >> +             return err;
    >> +     }
    >> +
    >> +     lhst->hdev->stat.byte_rx += skb->len;
    >> +
    >> +     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,
    >> +};
    >> +
    >> +/* 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 synchronize this and
    >> +              * st_registration_completion_cb() functions.
    >> +              */
    >> +             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->reg_status = -EINPROGRESS;
    >> +
    >> +             /* ST is busy with either protocol registration or firmware
    >> +              * download. Wait until the registration callback is called
    >> +              */
    >> +             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 status? */
    >> +             if (hst->reg_status != 0) {
    >> +                     BT_ERR("ST registration completed with invalid "
    >> +                                     "status %d", hst->reg_status);
    >> +                     return -EAGAIN;
    >> +             }
    >> +             err = 0;
    >> +     } else if (err == -EPERM) {
    >> +             BT_ERR("st_register failed %d", err);
    >> +             return err;
    >> +     }
    >
    > Again, you are checking for only EPERM and EINPROGRESS. You should check
    > for everything. I actually don't undertand why you have a special check
    > for EPERM.
    >
    >> +
    >> +     /* ti_st_proto.write is filled up by the underlying shared
    >> +      * transport driver upon registration
    >> +      */
    >> +     hst->st_write = ti_st_proto.write;
    >
    > I do not like that, the underlying should export the write function.
    >
    >> +     if (!hst->st_write) {
    >> +             BT_ERR("undefined ST write function");
    >> +
    >> +             /* Undo registration with ST */
    >> +             err = st_unregister(ST_BT);
    >> +             if (err)
    >> +                     BT_ERR("st_unregister() failed with error %d", err);
    >> +
    >> +             hst->st_write = NULL;
    >> +             return err;
    >> +     }
    >> +
    >> +     /* Registration with ST layer is successful,
    >> +      * hardware is ready to accept commands from HCI core.
    >> +      */
    >> +     if (test_and_set_bit(HCI_RUNNING, &hdev->flags)) {
    >> +             clear_bit(HCI_RUNNING, &hdev->flags);
    >> +             err = st_unregister(ST_BT);
    >> +             if (err)
    >> +                     BT_ERR("st_unregister() failed with error %d", err);
    >> +             hst->st_write = NULL;
    >> +     }
    >
    >
    > What are you trying to do here? test_and_set_bit() result doesn't say
    > nothing about error and you shall put test_and_set_bit should be in the
    > beginning, to know if your device is already opened or not and then
    > clear_bit if some error ocurrs during the function.
    >
    >> +
    >> +     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 with error %d", err);
    >> +
    >> +     hst->st_write = NULL;
    >> +
    >> +     if (!test_and_clear_bit(HCI_RUNNING, &hdev->flags))
    >> +             return 0;
    >
    > test_and_clear_bit should come first to check if your device is already
    > closed.
    >
    >> +
    >> +     return err;
    >> +}
    >> +
    >> +static int ti_st_send_frame(struct sk_buff *skb)
    >> +{
    >> +     struct hci_dev *hdev;
    >> +     struct ti_st *hst;
    >> +     long len;
    >> +
    >> +     hdev = (struct hci_dev *)skb->dev;
    >> +
    >> +     if (!test_bit(HCI_RUNNING, &hdev->flags))
    >> +             return -EBUSY;
    >> +
    >> +     hst = 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.
    >> +      */
    >> +     len = hst->st_write(skb);
    >> +     if (len < 0) {
    >> +             kfree_skb(skb);
    >> +             BT_ERR(" ST write failed (%ld)", len);
    >> +             return -EAGAIN;
    >
    > Why 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);
    >
    > From Marcel in the other thread:
    > "What is the reason for this deferred stats update. That code looks
    > pretty much hackish to me."
    >
    >> +
    >> +     return 0;
    >> +}
    >> +
    >> +static void ti_st_destruct(struct hci_dev *hdev)
    >> +{
    >> +     BT_DBG("%s", hdev->name);
    >> +
    >> +     /* free ti_st memory */
    >
    > get ride of the comment, it's pointless
    >
    >> +     kfree(hdev->driver_data);
    >> +
    >> +     return;
    >
    > No return; here
    >
    >> +}
    >> +
    >> +static int bt_ti_probe(struct platform_device *pdev)
    >> +{
    >> +     static struct ti_st *hst;
    >> +     struct hci_dev *hdev;
    >> +     int err;
    >> +
    >> +     hst = kzalloc(sizeof(struct ti_st), GFP_KERNEL);
    >> +     if (!hst)
    >> +             return -ENOMEM;
    >> +
    >> +     /* Expose "hciX" device to user space */
    >> +     hdev = hci_alloc_dev();
    >> +     if (!hdev)
    >> +             return -ENOMEM;
    >
    > You are leaking hst, if hci_alloc_dev() fails.
    >
    >> +
    >> +     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;
    >> +
    >> +     err = hci_register_dev(hdev);
    >> +     if (err < 0) {
    >> +             BT_ERR("Can't register HCI device error %d", err);
    >> +             hci_free_dev(hdev);
    >> +             return err;
    >> +     }
    >> +
    >> +     BT_DBG(" HCI device registered (hdev %p)", hdev);
    >> +
    >> +     dev_set_drvdata(&pdev->dev, hst);
    >> +     return err;
    >> +}
    >> +
    >> +static int bt_ti_remove(struct platform_device *pdev)
    >> +{
    >> +     struct hci_dev *hdev;
    >> +     struct ti_st *hst = dev_get_drvdata(&pdev->dev);
    >> +
    >> +     if (!hst)
    >> +             return -EFAULT;
    >> +
    >> +     hdev = hst->hdev;
    >> +     ti_st_close(hdev);
    >> +     hci_unregister_dev(hdev);
    >> +
    >> +     /* Free HCI device memory */
    >> +     hci_free_dev(hdev);
    >> +
    >> +     /* Free driver data memory */
    >
    > get ride of both commnets here. The name of the funcion is already
    > saying that.
    >
    >> +     kfree(hst);
    >> +
    >> +     dev_set_drvdata(&pdev->dev, NULL);
    >> +     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 btwilink_init(void)
    >> +{
    >> +     long ret;
    >> +
    >> +     BT_INFO(" Bluetooth Driver for TI WiLink - Version %s", VERSION);
    >> +
    >> +     ret = platform_driver_register(&btwilink_driver);
    >> +     if (ret != 0) {
    >> +             BT_ERR("btwilink platform driver registration failed");
    >> +             return ret;
    >> +     }
    >> +     return 0;
    >
    > Old issue again:
    >
    > From Marcel: please just do like we do with all other drivers;
    >
    >        BT_INFO(...)
    >
    >        return platform_driver_register(&btwilink_driver);
    >
    > --
    > Gustavo F. Padovan
    > http://profusion.mobi
    > --
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