Date:	Fri, 21 Jan 2011 15:57:18 -0200
From:	"Gustavo F. Padovan" <padovan@...fusion.mobi>
To:	pavan_savoy@...com
Cc:	marcel@...tmann.org, linux-kernel@...r.kernel.org,
	linux-bluetooth@...r.kernel.org
Subject: Re: [RFC 2/2] Bluetooth: btwilink driver

Hi Pavan,

* pavan_savoy@...com <pavan_savoy@...com> [2011-01-04 04:59:48 -0600]:

> From: Pavan Savoy <pavan_savoy@...com>
> 
> -- 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@...com>
> ---
>  drivers/bluetooth/Kconfig    |   10 +
>  drivers/bluetooth/Makefile   |    1 +
>  drivers/bluetooth/btwilink.c |  397 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 408 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..0201aca
> --- /dev/null
> +++ b/drivers/bluetooth/btwilink.c
> @@ -0,0 +1,397 @@
> +/*
> + *  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@...com>
> + *	Pavan Savoy <pavan_savoy@...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[3] = {
> +	{
> +		.chnl_id = 0x02, /* ACL */

Please create macros for the chnl_id in the core driver.

> +		.recv = st_receive,
> +		.reg_complete_cb = st_registration_completion_cb,
> +		.hdr_len = 4,
> +		.offset_len_in_hdr = 2,
> +		.len_size = 2,
> +		.reserve = 8,
> +	},
> +	{
> +		.chnl_id = 0x03, /* SCO */
> +		.recv = st_receive,
> +		.reg_complete_cb = st_registration_completion_cb,
> +		.hdr_len = 3,
> +		.offset_len_in_hdr = 2,
> +		.len_size = 1,
> +		.reserve = 8,
> +	},
> +	{
> +		.chnl_id = 0x04, /* HCI Events */
> +		.recv = st_receive,
> +		.reg_complete_cb = st_registration_completion_cb,
> +		.hdr_len = 2,
> +		.offset_len_in_hdr = 1,
> +		.len_size = 1,
> +		.reserve = 8,
> +	},
> +};
> +
> +/* 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, i;
> +
> +	BT_DBG("%s %p", hdev->name, hdev);

Blank line here.

> +	if (test_and_set_bit(HCI_RUNNING, &hdev->flags)) {
> +		BT_ERR("btwilink already opened");

No need for this BT_ERR. It already returns -EBUSY.

> +		return -EBUSY;
> +	}
> +
> +	/* provide contexts for callbacks from ST */
> +	hst = hdev->driver_data;
> +
> +	for (i = 0; i < 3; i++) {
> +		ti_st_proto[i].priv_data = hst;
> +		ti_st_proto[i].max_frame_size = HCI_MAX_FRAME_SIZE;
> +
> +		err = st_register(&ti_st_proto[i]);

Let's change the order here. First

		if (!err)
			goto to "hst->st_write = ti_st_proto[i].write"

		if (err != -EINPROGRESS) {
		}

		then here code for err == -EINPROGRESS


> +		if (err == -EINPROGRESS) {
> +			/* ST is busy with either protocol
> +			 * registration or firmware download.
> +			 */
> +			/* Prepare wait-for-completion handler data structures.
> +			*/
> +			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;
> +
> +			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) {
> +				clear_bit(HCI_RUNNING, &hdev->flags);
> +				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) {
> +				clear_bit(HCI_RUNNING, &hdev->flags);
> +				BT_ERR("ST registration completed with invalid "
> +						"status %d", hst->reg_status);
> +				return -EAGAIN;
> +			}
> +			err = 0;

remove this err = 0; and return 0 in the end of the function.

> +		} else if (err != 0) {
> +			clear_bit(HCI_RUNNING, &hdev->flags);
> +			BT_ERR("st_register failed %d", err);
> +			return err;
> +		}

Blank line here.

> +		hst->st_write = ti_st_proto[i].write;
> +		if (!hst->st_write) {
> +			BT_ERR("undefined ST write function");
> +			clear_bit(HCI_RUNNING, &hdev->flags);
> +
> +			/* Undo registration with ST */
> +			err = st_unregister(&ti_st_proto[i]);
> +			if (err)
> +				BT_ERR("st_unregister() failed with "
> +				"error %d", err);


You are unregistering only one protocol here, if the fail happens in the third
one you will leak two of them.

> +
> +			hst->st_write = NULL;
> +			/* ti_st_proto.write is filled up by the
> +			 * underlying shared transport driver
> +			 * upon registration
> +			 */
> +			return err;
> +		}
> +	}
> +
> +	return err;
> +}
> +
> +/* Close device */
> +static int ti_st_close(struct hci_dev *hdev)
> +{
> +	int err, i;
> +	struct ti_st *hst = hdev->driver_data;
> +
> +	if (!test_and_clear_bit(HCI_RUNNING, &hdev->flags))
> +		return 0;
> +
> +	for (i = 0; i < 3; i++) {
> +		/* continue to unregister from transport */

This comment is pointless.

> +		err = st_unregister(&ti_st_proto[i]);
> +		if (err)
> +			BT_ERR("st_unregister() failed with error %d", err);
> +	}
> +
> +	hst->st_write = NULL;
> +
> +	return err;

err is will report the error if it happens in the first or second unregister.


-- 
Gustavo F. Padovan
http://profusion.mobi
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