Date:	Thu, 7 Oct 2010 15:45:34 -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 1/2] drivers:bluetooth: TI_ST bluetooth driver

Hi Pavan,

Change the commit subject to "Bluetooth: TI_ST bluetooth driver" 

* pavan_savoy@...com <pavan_savoy@...com> [2010-10-07 14:47:16 -0400]:

> From: Pavan Savoy <pavan_savoy@...com>
> 
> 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.
> 
> Signed-off-by: Pavan Savoy <pavan_savoy@...com>
> ---
>  drivers/bluetooth/bt_ti.c |  489 +++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 489 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/bluetooth/bt_ti.c

We don't have filename with bt_.. in drivers/bluetooth/. Maybe ti_st.c
should be a better name, or something like that.

> 
> diff --git a/drivers/bluetooth/bt_ti.c b/drivers/bluetooth/bt_ti.c
> new file mode 100644
> index 0000000..dffbb56
> --- /dev/null
> +++ b/drivers/bluetooth/bt_ti.c
> @@ -0,0 +1,489 @@
> +/*
> + *  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 */
> +
> +/* BT driver's local status */
> +#define BT_DRV_RUNNING        0
> +#define BT_ST_REGISTERED      1
> +
> +/**
> + * struct hci_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 hci_st_open
> + *	and hci_st_registration_completion_cb.
> + */
> +struct hci_st {
> +	struct hci_dev *hdev;
> +	unsigned long flags;
> +	char streg_cbdata;
> +	long (*st_write) (struct sk_buff *);
> +	struct completion wait_for_btdrv_reg_completion;
> +};
> +
> +static int reset;
> +
> +/* Increments HCI counters based on pocket ID (cmd,acl,sco) */
> +static inline void hci_st_tx_complete(struct hci_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.cmd_tx++;

it should be sco_tx here.

> +		break;
> +	}
> +}
> +
> +/* ------- Interfaces to Shared Transport ------ */
> +
> +/* Called by ST layer to indicate protocol registration completion
> + * status.hci_st_open() function will wait for signal from this
> + * API when st_register() function returns ST_PENDING.
> + */
> +static void hci_st_registration_completion_cb(void *priv_data, char data)

That is not the hci layer, so rename this function (and the others) to
something that reflect where they are really doing.

> +{
> +	struct hci_st *lhst = (struct hci_st *)priv_data;
> +	/* hci_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 hci_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 hci_st_receive(void *priv_data, struct sk_buff *skb)
> +{
> +	int err;
> +	int len;

you can put err and len in the same line.

> +	struct hci_st *lhst = (struct hci_st *)priv_data;
> +
> +	err = 0;
> +	len = 0;

and no need to set them to 0 here.

> +
> +	if (skb == NULL) {
> +		BT_ERR("Invalid SKB received from ST");
> +		return -EFAULT;
> +	}

We need a empty line here.

> +	if (!lhst) {
> +		kfree_skb(skb);
> +		BT_ERR("Invalid hci_st memory,freeing SKB");
> +		return -EFAULT;
> +	}

And also here. Check the rest of the code for similar issues.

> +	if (!test_bit(BT_DRV_RUNNING, &lhst->flags)) {
> +		kfree_skb(skb);
> +		BT_ERR("Device is not running,freeing SKB");
> +		return -EINVAL;
> +	}

If you are here, your device is running, right? Or am I missing
something?

> +
> +	len = skb->len;
> +	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),freeing SKB",
> +				err);
> +		return err;
> +	}
> +	lhst->hdev->stat.byte_rx += len;

actually you even don't need len, just use skb->len

> +
> +	return 0;
> +}
> +
> +/* ------- Interfaces to HCI layer ------ */
> +
> +/* Called from HCI core to initialize the device */
> +static int hci_st_open(struct hci_dev *hdev)
> +{
> +	static struct st_proto_s hci_st_proto;
> +	unsigned long timeleft;
> +	struct hci_st *hst;
> +	int err;
> +	err = 0;
> +
> +	BT_DBG("%s %p", hdev->name, hdev);
> +	hst = hdev->driver_data;
> +
> +	/* Populate BT driver info required by ST */
> +	memset(&hci_st_proto, 0, sizeof(hci_st_proto));
> +
> +	/* BT driver ID */
> +	hci_st_proto.type = ST_BT;
> +
> +	/* Receive function which called from ST */
> +	hci_st_proto.recv = hci_st_receive;
> +
> +	/* Packet match function may used in future */
> +	hci_st_proto.match_packet = NULL;

It is already NULL, you dua a memset.

> +
> +	/* Callback to be called when registration is pending */
> +	hci_st_proto.reg_complete_cb = hci_st_registration_completion_cb;
> +
> +	/* This is write function pointer of ST. BT driver will make use of this
> +	 * for sending any packets to chip. ST will assign and give to us, so
> +	 * make it as NULL */
> +	hci_st_proto.write = NULL;

Same here.

> +
> +	/* send in the hst to be received at registration complete callback
> +	 * and during st's receive
> +	 */
> +	hci_st_proto.priv_data = hst;
> +
> +	/* Register with ST layer */
> +	err = st_register(&hci_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);

I'm not liking that, but I'll leave for Marcel and others comment.

> +
> +		/* Reset ST registration callback status flag , this value
> +		 * will be updated in hci_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__);
> +
> +		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 proper error macro instead "-1" 

> +		BT_ERR("st_register failed %d", err);
> +		return -EAGAIN;
> +	}
> +
> +	/* Do we have proper ST write function? */
> +	if (hci_st_proto.write != NULL) {
> +		/* We need this pointer for sending any Bluetooth pkts */
> +		hst->st_write = hci_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
> +	 */
> +	set_bit(HCI_RUNNING, &hdev->flags);
> +
> +	/* Registration with ST successful */
> +	set_bit(BT_ST_REGISTERED, &hst->flags);
> +
> +	return err;
> +}
> +
> +/* Close device */
> +static int hci_st_close(struct hci_dev *hdev)
> +{
> +	int err;
> +	struct hci_st *hst;

Skip a line after declarations.

> +	err = 0;

you can set err to 0 in the declaration if you really need that.

> +
> +	hst = hdev->driver_data;
> +	/* Unregister from ST layer */
> +	if (test_and_clear_bit(BT_ST_REGISTERED, &hst->flags)) {
> +		err = st_unregister(ST_BT);
> +		if (err != 0) {
> +			BT_ERR("st_unregister failed %d", err);
> +			return -EBUSY;
> +		}
> +	}
> +
> +	hst->st_write = NULL;
> +
> +	/* ST layer would have moved chip to inactive state.
> +	 * So,clear HCI device RUNNING flag.
> +	 */
> +	if (!test_and_clear_bit(HCI_RUNNING, &hdev->flags))
> +		return 0;

Looks you are screwing up the flags here, if it fails on st_unregister()
and returns HCI_RUNNING should keep set?

> +
> +	return err;

Rethink how you are doing error handling here, it should no be
complicated like that.

> +}
> +
> +/* Called from HCI CORE , Sends frames to Shared Transport */
> +static int hci_st_send_frame(struct sk_buff *skb)
> +{
> +	struct hci_dev *hdev;
> +	struct hci_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");
> +		return -EBUSY;
> +	}
> +
> +	hst = (struct hci_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) {
> +		/* Something went wrong in st write , free skb memory */

IMHO we don't need comments like that, clearly we now that something
went wrong.

> +		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;
> +	hci_st_tx_complete(hst, bt_cb(skb)->pkt_type);
> +
> +	return 0;

goto might be better to handle error here.


-- 
Gustavo F. Padovan
ProFUSION embedded systems - http://profusion.mobi
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