Date:	Thu, 14 Oct 2010 10:31:18 -0300
From:	"Gustavo F. Padovan" <padovan@...fusion.mobi>
To:	pavan_savoy@...com
Cc:	linux-bluetooth@...r.kernel.org, marcel@...tmann.org,
	greg@...ah.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: TI_ST bluetooth driver

Hi Pavan,

* pavan_savoy@...com <pavan_savoy@...com> [2010-10-11 12:33:23 -0400]:

> From: Pavan Savoy <pavan_savoy@...com>
> 
> Gustavo, Marcel,
> 
> I have taken care of most of the comments which you provided.
> Couple of them like usage of goto's, I didn't handle since
> I am not doing much error handling repeatedly there.
> 
> I have also removed the 2 states like _REGISTERED, _RUNNING which
> were not required and the flags associated with it.
> I have taken care of other style comments.
> 
> Please review and provide your comments,
> 
> -- 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 |  455 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 466 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/bluetooth/btwilink.c
> 
> 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"
> +	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..5351b62 100644
> --- a/drivers/bluetooth/Makefile
> +++ b/drivers/bluetooth/Makefile
> @@ -28,3 +28,4 @@ hci_uart-$(CONFIG_BT_HCIUART_BCSP)	+= hci_bcsp.o
>  hci_uart-$(CONFIG_BT_HCIUART_LL)	+= hci_ll.o
>  hci_uart-$(CONFIG_BT_HCIUART_ATH3K)	+= hci_ath.o
>  hci_uart-objs				:= $(hci_uart-y)
> +obj-$(CONFIG_BT_WILINK)			:= btwilink.o

sort this after:
obj-$(CONFIG_BT_MRVL_SDIO)      += btmrvl_sdio.o

> diff --git a/drivers/bluetooth/btwilink.c b/drivers/bluetooth/btwilink.c
> new file mode 100644
> index 0000000..e0bde79
> --- /dev/null
> +++ b/drivers/bluetooth/btwilink.c
> @@ -0,0 +1,455 @@
> +/*
> + *  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"
> +
> +/* Defines number of seconds to wait for reg completion
> + * callback getting called from ST (in case,registration
> + * with 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
> + * @flags: used locally,to maintain various BT driver status
> + * @streg_cbdata: to hold ST registration callback status
> + * @st_write: write function pointer of ST driver
> + * @wait_for_btdrv_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_for_btdrv_reg_completion;

wait_for_btdrv_reg_completion is too big.

> +};
> +
> +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;
> +	/* ti_st_open() function needs value of 'data' to know
> +	 * the registration status(success/fail),So have a back
> +	 * up of it.
> +	 */
> +	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.
> +	 */
> +	complete(&lhst->wait_for_btdrv_reg_completion);
> +}
> +
> +/* Called by Shared Transport layer when receive data is
> + * available */
> +static long st_receive(void *priv_data, struct sk_buff *skb)
> +{
> +	int err;
> +	struct ti_st *lhst = (struct ti_st *)priv_data;
> +
> +	if (skb == NULL) {
> +		BT_ERR("Invalid SKB received from ST");

I don't think this error message is worth.

> +		return -EFAULT;
> +	}

Make this (!skb) or the check below (lhst == NULL). Try to use only one
pattern in your code.


> +
> +	if (!lhst) {
> +		kfree_skb(skb);
> +		BT_ERR("Invalid ti_st memory,freeing SKB");

I don't think this error message is worth.

> +		return -EFAULT;
> +	}
> +
> +	skb->dev = (struct net_device *)lhst->hdev;

Blank line here.

> +	/* 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),freeing SKB",

Turn this message into:

"Unable to push skb to HCI core(%d)"

> +				err);
> +		return err;
> +	}
> +
> +	lhst->hdev->stat.byte_rx += skb->len;
> +	return 0;
> +}
> +
> +/* ------- Interfaces to HCI layer ------ */
> +
> +/* Called from HCI core to initialize the device */
> +static int ti_st_open(struct hci_dev *hdev)
> +{
> +	static struct st_proto_s ti_st_proto;

Usually we declare this outside of the function like this:

static struct usb_driver ath3k_driver = {
	.name           = "ath3k",
	.probe          = ath3k_probe,
	.disconnect     = ath3k_disconnect,
	.id_table       = ath3k_table,
};


> +	unsigned long timeleft;
> +	struct ti_st *hst;
> +	int err;
> +	err = 0;

No need to set err to 0 here.

> +
> +	BT_DBG("%s %p", hdev->name, hdev);

Skip a line here.

> +	hst = hdev->driver_data;
> +
> +	/* Populate BT driver info required by ST */
> +	memset(&ti_st_proto, 0, sizeof(ti_st_proto));
> +
> +	/* BT driver ID */
> +	ti_st_proto.type = ST_BT;
> +
> +	/* Receive function which called from ST */
> +	ti_st_proto.recv = st_receive;
> +
> +	/* Callback to be called when registration is pending */
> +	ti_st_proto.reg_complete_cb = st_registration_completion_cb;
> +
> +	/* send in the hst to be received at registration complete callback
> +	 * and during st's receive
> +	 */
> +	ti_st_proto.priv_data = hst;
> +
> +	/* Register with ST layer */

No need for this comment, your function name already set that.

> +	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.
> +		 */
> +		init_completion(&hst->wait_for_btdrv_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;
> +
> +		/* 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.
> +		 */
> +		BT_DBG(" %s waiting for reg completion signal from ST",
> +				__func__);

BT_DBG already have __func__.

> +
> +		timeleft =
> +			wait_for_completion_timeout

this could be:

		timeleft = wait_for_completion_timeout

> +			(&hst->wait_for_btdrv_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? */
> +		if (hst->streg_cbdata != 0) {
> +			BT_ERR("ST reg completion CB called with invalid"
> +					"status %d", hst->streg_cbdata);
> +			return -EAGAIN;
> +		}
> +		err = 0;
> +	} else if (err == -1) {

Use the error macro instead of -1

> +		BT_ERR("st_register failed %d", err);
> +		return -EAGAIN;
> +	}
> +
> +	/* 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;

Didn't get this. Who sets ti_st_proto.write()?

> +	} else {
> +		BT_ERR("failed to get ST write func pointer");
> +
> +		/* Undo registration with ST */
> +		err = st_unregister(ST_BT);
> +		if (err < 0)
> +			BT_ERR("st_unregister failed %d", err);
> +
> +		hst->st_write = NULL;
> +		return -EAGAIN;
> +	}
> +
> +	/* Registration with ST layer is completed successfully,
> +	 * now chip is ready to accept commands from HCI CORE.
> +	 * Mark HCI Device flag as RUNNING
> +	 */

I don't think this comment is worth, your code already says that.
But one can argue here that comments are always good. ;)

> +	set_bit(HCI_RUNNING, &hdev->flags);
> +	return err;
> +}
> +
> +/* Close device */
> +static int ti_st_close(struct hci_dev *hdev)
> +{
> +	int err = 0;
> +	struct ti_st *hst;
> +
> +	hst = hdev->driver_data;
> +
> +	/* Clear HCI device RUNNING flag */
> +	if (!test_and_clear_bit(HCI_RUNNING, &hdev->flags))
> +		BT_ERR("HCI not RUNNING?");

That's is not a error, just return 0.

> +
> +	/* continue to unregister from transport */
> +	err = st_unregister(ST_BT);
> +	if (err != 0) {
> +		hst->st_write = NULL;
> +		BT_ERR("st_unregister failed %d", err);
> +		return -EBUSY;
> +	}
> +
> +	hst->st_write = NULL;
> +	return err;

This should be better:

	if (err)
		BT_ERR("st_unregister failed %d", err);

	hst->st_write = NULL;
	return err;

> +}
> +
> +/* Called from HCI CORE , Sends frames to Shared Transport */
> +static int ti_st_send_frame(struct sk_buff *skb)
> +{
> +	struct hci_dev *hdev;
> +	struct ti_st *hst;
> +	long len;
> +
> +	if (skb == NULL) {
> +		BT_ERR("Invalid skb received from HCI CORE");
> +		return -ENOMEM;
> +	}
> +
> +	hdev = (struct hci_dev *)skb->dev;
> +	if (!hdev) {
> +		BT_ERR("SKB received for invalid HCI Device (hdev=NULL)");
> +		return -ENODEV;
> +	}
> +
> +	if (!test_bit(HCI_RUNNING, &hdev->flags)) {
> +		BT_ERR("Device is not running");

Remove the last 3 BT_ERR

> +		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?");
> +		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)");
> +		return;
> +	}
> +
> +	BT_DBG("%s", hdev->name);
> +
> +	/* free ti_st memory */
> +	if (hdev->driver_data != NULL)
> +		kfree(hdev->driver_data);
> +
> +	return;

No return; here

> +}
> +
> +/* Creates new HCI device */
> +static int ti_st_register_dev(struct ti_st *hst)
> +{
> +	struct hci_dev *hdev;
> +
> +	/* Initialize and register HCI device */
> +	hdev = hci_alloc_dev();
> +	if (!hdev) {
> +		BT_ERR("Can't allocate HCI device");
> +		return -ENOMEM;
> +	}
> +	BT_DBG(" HCI device allocated. 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);
> +
> +	if (hci_register_dev(hdev) < 0) {
> +		BT_ERR("Can't register HCI device");
> +		hci_free_dev(hdev);
> +		return -ENODEV;
> +	}
> +
> +	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;
> +	err = 0;
> +
> +	BT_DBG(" Bluetooth Driver Version %s", VERSION);
> +
> +	/* Allocate local resource memory */

I don't think this comment is needed.

> +	hst = kzalloc(sizeof(struct ti_st), GFP_KERNEL);
> +	if (!hst) {
> +		BT_ERR("Can't allocate control structure");

remove the BT_ERR

> +		return -ENFILE;

-ENOMEM

> +	}
> +
> +	/* Expose "hciX" device to user space */
> +	err = ti_st_register_dev(hst);
> +	if (err) {
> +		/* Release local resource memory */

I don't think this comment is needed.

> +		kfree(hst);
> +
> +		BT_ERR("Unable to expose hci0 device(%d)", err);

Are you sure that this is hci0?

> +		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  */
> +	if (hst) {
> +		struct hci_dev *hdev = hst->hdev;
> +		if (hdev == NULL) {
> +			BT_ERR("Invalid hdev memory");
> +			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 bt_ti_driver = {
> +	.probe = bt_ti_probe,
> +	.remove = bt_ti_remove,
> +	.driver = {
> +		.name = "ti_st_bluetooth",
> +		.owner = THIS_MODULE,
> +	},
> +};
> +
> +/* ------- Module Init/Exit interfaces ------ */
> +static int __init bt_drv_init(void)
> +{
> +long ret = 0;

Skip a line and don't set ret to 0.

> +	ret = platform_driver_register(&bt_ti_driver);
> +	if (ret != 0) {
> +		BT_ERR("bt_ti platform drv registration failed");
> +		return -1;

Why -1?

> +	}
> +	return 0;
> +}
> +
> +static void __exit bt_drv_exit(void)
> +{
> +	platform_driver_unregister(&bt_ti_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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-- 
Gustavo F. Padovan
ProFUSION embedded systems - http://profusion.mobi
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