caif-u5500: CAIF shared memory transport protocol

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 744 insertions, 0 deletions

diff --git a/drivers/net/caif/caif_shmcore.c b/drivers/net/caif/caif_shmcore.c
new file mode 100644
index 0000000..19f9c06
--- /dev/null
+++ b/drivers/net/caif/caif_shmcore.c
@@ -0,0 +1,744 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Contact: Sjur Brendeland / sjur.brandeland@stericsson.com
+ * Authors:  Amarnath Revanna / amarnath.bangalore.revanna@stericsson.com,
+ *           Daniel Martensson / daniel.martensson@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":" __func__ "():" fmt
+
+#include <linux/spinlock.h>
+#include <linux/sched.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+
+#include <net/caif/caif_device.h>
+#include <net/caif/caif_shm.h>
+
+#define NR_TX_BUF		6
+#define NR_RX_BUF		6
+#define TX_BUF_SZ		0x2000
+#define RX_BUF_SZ		0x2000
+
+#define CAIF_NEEDED_HEADROOM	32
+
+#define CAIF_FLOW_ON		1
+#define CAIF_FLOW_OFF		0
+
+#define LOW_WATERMARK		3
+#define HIGH_WATERMARK		4
+
+/* Maximum number of CAIF buffers per shared memory buffer. */
+#define SHM_MAX_FRMS_PER_BUF	10
+
+/*
+ * Size in bytes of the descriptor area
+ * (With end of descriptor signalling)
+ */
+#define SHM_CAIF_DESC_SIZE	((SHM_MAX_FRMS_PER_BUF + 1) * \
+					sizeof(struct shm_pck_desc))
+
+/*
+ * Offset to the first CAIF frame within a shared memory buffer.
+ * Aligned on 32 bytes.
+ */
+#define SHM_CAIF_FRM_OFS	(SHM_CAIF_DESC_SIZE + (SHM_CAIF_DESC_SIZE % 32))
+
+/* Number of bytes for CAIF shared memory header. */
+#define SHM_HDR_LEN		1
+
+/* Number of padding bytes for the complete CAIF frame. */
+#define SHM_FRM_PAD_LEN		4
+
+#define CAIF_MAX_MTU		4096
+
+#define SHM_SET_FULL(x)	(((x+1) & 0x0F) << 0)
+#define SHM_GET_FULL(x)	(((x >> 0) & 0x0F) - 1)
+
+#define SHM_SET_EMPTY(x)	(((x+1) & 0x0F) << 4)
+#define SHM_GET_EMPTY(x)	(((x >> 4) & 0x0F) - 1)
+
+#define SHM_FULL_MASK		(0x0F << 0)
+#define SHM_EMPTY_MASK		(0x0F << 4)
+
+struct shm_pck_desc {
+	/*
+	 * Offset from start of shared memory area to start of
+	 * shared memory CAIF frame.
+	 */
+	u32 frm_ofs;
+	u32 frm_len;
+};
+
+struct buf_list {
+	unsigned char *desc_vptr;
+	u32 phy_addr;
+	u32 index;
+	u32 len;
+	u32 frames;
+	u32 frm_ofs;
+	struct list_head list;
+};
+
+struct shm_caif_frm {
+	/* Number of bytes of padding before the CAIF frame. */
+	u8 hdr_ofs;
+};
+
+struct shmdrv_layer {
+	/* caif_dev_common must always be first in the structure*/
+	struct caif_dev_common cfdev;
+
+	u32 shm_tx_addr;
+	u32 shm_rx_addr;
+	u32 shm_base_addr;
+	u32 tx_empty_available;
+	spinlock_t lock;
+
+	struct list_head tx_empty_list;
+	struct list_head tx_pend_list;
+	struct list_head tx_full_list;
+	struct list_head rx_empty_list;
+	struct list_head rx_pend_list;
+	struct list_head rx_full_list;
+
+	struct workqueue_struct *pshm_tx_workqueue;
+	struct workqueue_struct *pshm_rx_workqueue;
+
+	struct work_struct shm_tx_work;
+	struct work_struct shm_rx_work;
+
+	struct sk_buff_head sk_qhead;
+	struct shmdev_layer *pshm_dev;
+};
+
+static int shm_netdev_open(struct net_device *shm_netdev)
+{
+	netif_wake_queue(shm_netdev);
+	return 0;
+}
+
+static int shm_netdev_close(struct net_device *shm_netdev)
+{
+	netif_stop_queue(shm_netdev);
+	return 0;
+}
+
+int caif_shmdrv_rx_cb(u32 mbx_msg, void *priv)
+{
+	struct buf_list *pbuf;
+	struct shmdrv_layer *pshm_drv;
+	struct list_head *pos;
+	u32 avail_emptybuff = 0;
+	unsigned long flags = 0;
+
+	pshm_drv = (struct shmdrv_layer *)priv;
+
+	/* Check for received buffers. */
+	if (mbx_msg & SHM_FULL_MASK) {
+		int idx;
+
+		spin_lock_irqsave(&pshm_drv->lock, flags);
+
+		/* Check whether we have any outstanding buffers. */
+		if (list_empty(&pshm_drv->rx_empty_list)) {
+
+			/* Release spin lock. */
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+			/* We print even in IRQ context... */
+			pr_warn("No empty Rx buffers to fill: "
+					"mbx_msg:%x\n", mbx_msg);
+
+			/* Bail out. */
+			goto err_sync;
+		}
+
+		pbuf =
+			list_entry(pshm_drv->rx_empty_list.next,
+					struct buf_list, list);
+		idx = pbuf->index;
+
+		/* Check buffer synchronization. */
+		if (idx != SHM_GET_FULL(mbx_msg)) {
+
+			/* We print even in IRQ context... */
+			pr_warn(
+			"phyif_shm_mbx_msg_cb: RX full out of sync:"
+			" idx:%d, msg:%x SHM_GET_FULL(mbx_msg):%x\n",
+				idx, mbx_msg, SHM_GET_FULL(mbx_msg));
+
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+			/* Bail out. */
+			goto err_sync;
+		}
+
+		list_del_init(&pbuf->list);
+		list_add_tail(&pbuf->list, &pshm_drv->rx_full_list);
+
+		spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+		/* Schedule RX work queue. */
+		if (!work_pending(&pshm_drv->shm_rx_work))
+			queue_work(pshm_drv->pshm_rx_workqueue,
+						&pshm_drv->shm_rx_work);
+	}
+
+	/* Check for emptied buffers. */
+	if (mbx_msg & SHM_EMPTY_MASK) {
+		int idx;
+
+		spin_lock_irqsave(&pshm_drv->lock, flags);
+
+		/* Check whether we have any outstanding buffers. */
+		if (list_empty(&pshm_drv->tx_full_list)) {
+
+			/* We print even in IRQ context... */
+			pr_warn("No TX to empty: msg:%x\n", mbx_msg);
+
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+			/* Bail out. */
+			goto err_sync;
+		}
+
+		pbuf =
+			list_entry(pshm_drv->tx_full_list.next,
+					struct buf_list, list);
+		idx = pbuf->index;
+
+		/* Check buffer synchronization. */
+		if (idx != SHM_GET_EMPTY(mbx_msg)) {
+
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+			/* We print even in IRQ context... */
+			pr_warn("TX empty "
+				"out of sync:idx:%d, msg:%x\n", idx, mbx_msg);
+
+			/* Bail out. */
+			goto err_sync;
+		}
+		list_del_init(&pbuf->list);
+
+		/* Reset buffer parameters. */
+		pbuf->frames = 0;
+		pbuf->frm_ofs = SHM_CAIF_FRM_OFS;
+
+		list_add_tail(&pbuf->list, &pshm_drv->tx_empty_list);
+
+		/* Check the available no. of buffers in the empty list */
+		list_for_each(pos, &pshm_drv->tx_empty_list)
+			avail_emptybuff++;
+
+		/* Check whether we have to wake up the transmitter. */
+		if ((avail_emptybuff > HIGH_WATERMARK) &&
+					(!pshm_drv->tx_empty_available)) {
+			pshm_drv->tx_empty_available = 1;
+			pshm_drv->cfdev.flowctrl
+					(pshm_drv->pshm_dev->pshm_netdev,
+								CAIF_FLOW_ON);
+
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+			/* Schedule the work queue. if required */
+			if (!work_pending(&pshm_drv->shm_tx_work))
+				queue_work(pshm_drv->pshm_tx_workqueue,
+							&pshm_drv->shm_tx_work);
+		} else
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+	}
+
+	return 0;
+
+err_sync:
+	return -EIO;
+}
+
+static void shm_rx_work_func(struct work_struct *rx_work)
+{
+	struct shmdrv_layer *pshm_drv;
+	struct buf_list *pbuf;
+	unsigned long flags = 0;
+	struct sk_buff *skb;
+	char *p;
+	int ret;
+
+	pshm_drv = container_of(rx_work, struct shmdrv_layer, shm_rx_work);
+
+	while (1) {
+
+		struct shm_pck_desc *pck_desc;
+
+		spin_lock_irqsave(&pshm_drv->lock, flags);
+
+		/* Check for received buffers. */
+		if (list_empty(&pshm_drv->rx_full_list)) {
+			spin_unlock_irqrestore(&pshm_drv->lock, flags);
+			break;
+		}
+
+		pbuf =
+			list_entry(pshm_drv->rx_full_list.next, struct buf_list,
+					list);
+		list_del_init(&pbuf->list);
+
+		/* Retrieve pointer to start of the packet descriptor area. */
+		pck_desc = (struct shm_pck_desc *) pbuf->desc_vptr;
+
+		/*
+		 * Check whether descriptor contains a CAIF shared memory
+		 * frame.
+		 */
+		while (pck_desc->frm_ofs) {
+			unsigned int frm_buf_ofs;
+			unsigned int frm_pck_ofs;
+			unsigned int frm_pck_len;
+			/*
+			 * Check whether offset is within buffer limits
+			 * (lower).
+			 */
+			if (pck_desc->frm_ofs <
+				(pbuf->phy_addr - pshm_drv->shm_base_addr))
+				break;
+			/*
+			 * Check whether offset is within buffer limits
+			 * (higher).
+			 */
+			if (pck_desc->frm_ofs >
+				((pbuf->phy_addr - pshm_drv->shm_base_addr) +
+					pbuf->len))
+				break;
+
+			/* Calculate offset from start of buffer. */
+			frm_buf_ofs =
+				pck_desc->frm_ofs - (pbuf->phy_addr -
+						pshm_drv->shm_base_addr);
+
+			/*
+			 * Calculate offset and length of CAIF packet while
+			 * taking care of the shared memory header.
+			 */
+			frm_pck_ofs =
+				frm_buf_ofs + SHM_HDR_LEN +
+				(*(pbuf->desc_vptr + frm_buf_ofs));
+			frm_pck_len =
+				(pck_desc->frm_len - SHM_HDR_LEN -
+				(*(pbuf->desc_vptr + frm_buf_ofs)));
+
+			/* Check whether CAIF packet is within buffer limits */
+			if ((frm_pck_ofs + pck_desc->frm_len) > pbuf->len)
+				break;
+
+			/* Get a suitable CAIF packet and copy in data. */
+			skb = netdev_alloc_skb(pshm_drv->pshm_dev->pshm_netdev,
+							frm_pck_len + 1);
+			BUG_ON(skb == NULL);
+
+			p = skb_put(skb, frm_pck_len);
+			memcpy(p, pbuf->desc_vptr + frm_pck_ofs, frm_pck_len);
+
+			skb->protocol = htons(ETH_P_CAIF);
+			skb_reset_mac_header(skb);
+			skb->dev = pshm_drv->pshm_dev->pshm_netdev;
+
+			/* Push received packet up the stack. */
+			ret = netif_rx_ni(skb);
+
+			if (!ret) {
+				pshm_drv->pshm_dev->pshm_netdev->stats.
+								rx_packets++;
+				pshm_drv->pshm_dev->pshm_netdev->stats.
+						rx_bytes += pck_desc->frm_len;
+			} else
+				++pshm_drv->pshm_dev->pshm_netdev->stats.
+								rx_dropped;
+			/* Move to next packet descriptor. */
+			pck_desc++;
+		}
+
+		list_add_tail(&pbuf->list, &pshm_drv->rx_pend_list);
+
+		spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+	}
+
+	/* Schedule the work queue. if required */
+	if (!work_pending(&pshm_drv->shm_tx_work))
+		queue_work(pshm_drv->pshm_tx_workqueue, &pshm_drv->shm_tx_work);
+
+}
+
+static void shm_tx_work_func(struct work_struct *tx_work)
+{
+	u32 mbox_msg;
+	unsigned int frmlen, avail_emptybuff, append = 0;
+	unsigned long flags = 0;
+	struct buf_list *pbuf = NULL;
+	struct shmdrv_layer *pshm_drv;
+	struct shm_caif_frm *frm;
+	struct sk_buff *skb;
+	struct shm_pck_desc *pck_desc;
+	struct list_head *pos;
+
+	pshm_drv = container_of(tx_work, struct shmdrv_layer, shm_tx_work);
+
+	do {
+		/* Initialize mailbox message. */
+		mbox_msg = 0x00;
+		avail_emptybuff = 0;
+
+		spin_lock_irqsave(&pshm_drv->lock, flags);
+
+		/* Check for pending receive buffers. */
+		if (!list_empty(&pshm_drv->rx_pend_list)) {
+
+			pbuf = list_entry(pshm_drv->rx_pend_list.next,
+						struct buf_list, list);
+
+			list_del_init(&pbuf->list);
+			list_add_tail(&pbuf->list, &pshm_drv->rx_empty_list);
+			/*
+			 * Value index is never changed,
+			 * so read access should be safe.
+			 */
+			mbox_msg |= SHM_SET_EMPTY(pbuf->index);
+		}
+
+		skb = skb_peek(&pshm_drv->sk_qhead);
+
+		if (skb == NULL)
+			goto send_msg;
+
+		/* Check the available no. of buffers in the empty list */
+		list_for_each(pos, &pshm_drv->tx_empty_list)
+			avail_emptybuff++;
+
+		if ((avail_emptybuff < LOW_WATERMARK) &&
+					pshm_drv->tx_empty_available) {
+			/* Update blocking condition. */
+			pshm_drv->tx_empty_available = 0;
+			pshm_drv->cfdev.flowctrl
+					(pshm_drv->pshm_dev->pshm_netdev,
+					CAIF_FLOW_OFF);
+		}
+		/*
+		 * We simply return back to the caller if we do not have space
+		 * either in Tx pending list or Tx empty list. In this case,
+		 * we hold the received skb in the skb list, waiting to
+		 * be transmitted once Tx buffers become available
+		 */
+		if (list_empty(&pshm_drv->tx_empty_list))
+			goto send_msg;
+
+		/* Get the first free Tx buffer. */
+		pbuf = list_entry(pshm_drv->tx_empty_list.next,
+						struct buf_list, list);
+		do {
+			if (append) {
+				skb = skb_peek(&pshm_drv->sk_qhead);
+				if (skb == NULL)
+					break;
+			}
+
+			frm = (struct shm_caif_frm *)
+					(pbuf->desc_vptr + pbuf->frm_ofs);
+
+			frm->hdr_ofs = 0;
+			frmlen = 0;
+			frmlen += SHM_HDR_LEN + frm->hdr_ofs + skb->len;
+
+			/* Add tail padding if needed. */
+			if (frmlen % SHM_FRM_PAD_LEN)
+				frmlen += SHM_FRM_PAD_LEN -
+						(frmlen % SHM_FRM_PAD_LEN);
+
+			/*
+			 * Verify that packet, header and additional padding
+			 * can fit within the buffer frame area.
+			 */
+			if (frmlen >= (pbuf->len - pbuf->frm_ofs))
+				break;
+
+			if (!append) {
+				list_del_init(&pbuf->list);
+				append = 1;
+			}
+
+			skb = skb_dequeue(&pshm_drv->sk_qhead);
+			/* Copy in CAIF frame. */
+			skb_copy_bits(skb, 0, pbuf->desc_vptr +
+					pbuf->frm_ofs + SHM_HDR_LEN +
+						frm->hdr_ofs, skb->len);
+
+			pshm_drv->pshm_dev->pshm_netdev->stats.tx_packets++;
+			pshm_drv->pshm_dev->pshm_netdev->stats.tx_bytes +=
+									frmlen;
+			dev_kfree_skb(skb);
+
+			/* Fill in the shared memory packet descriptor area. */
+			pck_desc = (struct shm_pck_desc *) (pbuf->desc_vptr);
+			/* Forward to current frame. */
+			pck_desc += pbuf->frames;
+			pck_desc->frm_ofs = (pbuf->phy_addr -
+						pshm_drv->shm_base_addr) +
+								pbuf->frm_ofs;
+			pck_desc->frm_len = frmlen;
+			/* Terminate packet descriptor area. */
+			pck_desc++;
+			pck_desc->frm_ofs = 0;
+			/* Update buffer parameters. */
+			pbuf->frames++;
+			pbuf->frm_ofs += frmlen + (frmlen % 32);
+
+		} while (pbuf->frames < SHM_MAX_FRMS_PER_BUF);
+
+		/* Assign buffer as full. */
+		list_add_tail(&pbuf->list, &pshm_drv->tx_full_list);
+		append = 0;
+		mbox_msg |= SHM_SET_FULL(pbuf->index);
+send_msg:
+		spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+		if (mbox_msg)
+			pshm_drv->pshm_dev->pshmdev_mbxsend
+					(pshm_drv->pshm_dev->shm_id, mbox_msg);
+	} while (mbox_msg);
+}
+
+static int shm_netdev_tx(struct sk_buff *skb, struct net_device *shm_netdev)
+{
+	struct shmdrv_layer *pshm_drv;
+	unsigned long flags = 0;
+
+	pshm_drv = netdev_priv(shm_netdev);
+
+	spin_lock_irqsave(&pshm_drv->lock, flags);
+
+	skb_queue_tail(&pshm_drv->sk_qhead, skb);
+
+	spin_unlock_irqrestore(&pshm_drv->lock, flags);
+
+	/* Schedule Tx work queue. for deferred processing of skbs*/
+	if (!work_pending(&pshm_drv->shm_tx_work))
+		queue_work(pshm_drv->pshm_tx_workqueue, &pshm_drv->shm_tx_work);
+
+	return 0;
+}
+
+static const struct net_device_ops netdev_ops = {
+	.ndo_open = shm_netdev_open,
+	.ndo_stop = shm_netdev_close,
+	.ndo_start_xmit = shm_netdev_tx,
+};
+
+static void shm_netdev_setup(struct net_device *pshm_netdev)
+{
+	struct shmdrv_layer *pshm_drv;
+	pshm_netdev->netdev_ops = &netdev_ops;
+
+	pshm_netdev->mtu = CAIF_MAX_MTU;
+	pshm_netdev->type = ARPHRD_CAIF;
+	pshm_netdev->hard_header_len = CAIF_NEEDED_HEADROOM;
+	pshm_netdev->tx_queue_len = 0;
+	pshm_netdev->destructor = free_netdev;
+
+	pshm_drv = netdev_priv(pshm_netdev);
+
+	/* Initialize structures in a clean state. */
+	memset(pshm_drv, 0, sizeof(struct shmdrv_layer));
+
+	pshm_drv->cfdev.link_select = CAIF_LINK_LOW_LATENCY;
+}
+
+int caif_shmcore_probe(struct shmdev_layer *pshm_dev)
+{
+	int result, j;
+	struct shmdrv_layer *pshm_drv = NULL;
+
+	pshm_dev->pshm_netdev = alloc_netdev(sizeof(struct shmdrv_layer),
+						"cfshm%d", shm_netdev_setup);
+	if (!pshm_dev->pshm_netdev)
+		return -ENOMEM;
+
+	pshm_drv = netdev_priv(pshm_dev->pshm_netdev);
+	pshm_drv->pshm_dev = pshm_dev;
+
+	/*
+	 * Initialization starts with the verification of the
+	 * availability of MBX driver by calling its setup function.
+	 * MBX driver must be available by this time for proper
+	 * functioning of SHM driver.
+	 */
+	if ((pshm_dev->pshmdev_mbxsetup
+				(caif_shmdrv_rx_cb, pshm_dev, pshm_drv)) != 0) {
+		pr_warn("Could not config. SHM Mailbox,"
+				" Bailing out.....\n");
+		free_netdev(pshm_dev->pshm_netdev);
+		return -ENODEV;
+	}
+
+	skb_queue_head_init(&pshm_drv->sk_qhead);
+
+	pr_info("SHM DEVICE[%d] PROBED BY DRIVER, NEW SHM DRIVER"
+			" INSTANCE AT pshm_drv =0x%p\n",
+			pshm_drv->pshm_dev->shm_id, pshm_drv);
+
+	if (pshm_dev->shm_total_sz <
+			(NR_TX_BUF * TX_BUF_SZ + NR_RX_BUF * RX_BUF_SZ)) {
+
+		pr_warn("ERROR, Amount of available"
+				" Phys. SHM cannot accomodate current SHM "
+				"driver configuration, Bailing out ...\n");
+		free_netdev(pshm_dev->pshm_netdev);
+		return -ENOMEM;
+	}
+
+	pshm_drv->shm_base_addr = pshm_dev->shm_base_addr;
+	pshm_drv->shm_tx_addr = pshm_drv->shm_base_addr;
+
+	if (pshm_dev->shm_loopback)
+		pshm_drv->shm_rx_addr = pshm_drv->shm_tx_addr;
+	else
+		pshm_drv->shm_rx_addr = pshm_dev->shm_base_addr +
+						(NR_TX_BUF * TX_BUF_SZ);
+
+	INIT_LIST_HEAD(&pshm_drv->tx_empty_list);
+	INIT_LIST_HEAD(&pshm_drv->tx_pend_list);
+	INIT_LIST_HEAD(&pshm_drv->tx_full_list);
+
+	INIT_LIST_HEAD(&pshm_drv->rx_empty_list);
+	INIT_LIST_HEAD(&pshm_drv->rx_pend_list);
+	INIT_LIST_HEAD(&pshm_drv->rx_full_list);
+
+	INIT_WORK(&pshm_drv->shm_tx_work, shm_tx_work_func);
+	INIT_WORK(&pshm_drv->shm_rx_work, shm_rx_work_func);
+
+	pshm_drv->pshm_tx_workqueue =
+				create_singlethread_workqueue("shm_tx_work");
+	pshm_drv->pshm_rx_workqueue =
+				create_singlethread_workqueue("shm_rx_work");
+
+	for (j = 0; j < NR_TX_BUF; j++) {
+		struct buf_list *tx_buf =
+				kmalloc(sizeof(struct buf_list), GFP_KERNEL);
+
+		if (tx_buf == NULL) {
+			pr_warn("ERROR, Could not"
+					" allocate dynamic mem. for tx_buf,"
+					" Bailing out ...\n");
+			free_netdev(pshm_dev->pshm_netdev);
+			return -ENOMEM;
+		}
+		tx_buf->index = j;
+		tx_buf->phy_addr = pshm_drv->shm_tx_addr + (TX_BUF_SZ * j);
+		tx_buf->len = TX_BUF_SZ;
+		tx_buf->frames = 0;
+		tx_buf->frm_ofs = SHM_CAIF_FRM_OFS;
+
+		if (pshm_dev->shm_loopback)
+			tx_buf->desc_vptr = (char *)tx_buf->phy_addr;
+		else
+			tx_buf->desc_vptr =
+					ioremap(tx_buf->phy_addr, TX_BUF_SZ);
+
+		list_add_tail(&tx_buf->list, &pshm_drv->tx_empty_list);
+	}
+
+	for (j = 0; j < NR_RX_BUF; j++) {
+		struct buf_list *rx_buf =
+				kmalloc(sizeof(struct buf_list), GFP_KERNEL);
+
+		if (rx_buf == NULL) {
+			pr_warn("ERROR, Could not"
+					" allocate dynamic mem.for rx_buf,"
+					" Bailing out ...\n");
+			free_netdev(pshm_dev->pshm_netdev);
+			return -ENOMEM;
+		}
+		rx_buf->index = j;
+		rx_buf->phy_addr = pshm_drv->shm_rx_addr + (RX_BUF_SZ * j);
+		rx_buf->len = RX_BUF_SZ;
+
+		if (pshm_dev->shm_loopback)
+			rx_buf->desc_vptr = (char *)rx_buf->phy_addr;
+		else
+			rx_buf->desc_vptr =
+					ioremap(rx_buf->phy_addr, RX_BUF_SZ);
+		list_add_tail(&rx_buf->list, &pshm_drv->rx_empty_list);
+	}
+
+	pshm_drv->tx_empty_available = 1;
+	result = register_netdev(pshm_dev->pshm_netdev);
+	if (result)
+		pr_warn("ERROR[%d], SHM could not, "
+			"register with NW FRMWK Bailing out ...\n", result);
+
+	return result;
+}
+
+void caif_shmcore_remove(struct net_device *pshm_netdev)
+{
+	struct buf_list *pbuf;
+	struct shmdrv_layer *pshm_drv = NULL;
+
+	pshm_drv = netdev_priv(pshm_netdev);
+
+	while (!(list_empty(&pshm_drv->tx_pend_list))) {
+		pbuf =
+			list_entry(pshm_drv->tx_pend_list.next,
+					struct buf_list, list);
+
+		list_del(&pbuf->list);
+		kfree(pbuf);
+	}
+
+	while (!(list_empty(&pshm_drv->tx_full_list))) {
+		pbuf =
+			list_entry(pshm_drv->tx_full_list.next,
+					struct buf_list, list);
+		list_del(&pbuf->list);
+		kfree(pbuf);
+	}
+
+	while (!(list_empty(&pshm_drv->tx_empty_list))) {
+		pbuf =
+			list_entry(pshm_drv->tx_empty_list.next,
+					struct buf_list, list);
+		list_del(&pbuf->list);
+		kfree(pbuf);
+	}
+
+	while (!(list_empty(&pshm_drv->rx_full_list))) {
+		pbuf =
+			list_entry(pshm_drv->tx_full_list.next,
+				struct buf_list, list);
+		list_del(&pbuf->list);
+		kfree(pbuf);
+	}
+
+	while (!(list_empty(&pshm_drv->rx_pend_list))) {
+		pbuf =
+			list_entry(pshm_drv->tx_pend_list.next,
+				struct buf_list, list);
+		list_del(&pbuf->list);
+		kfree(pbuf);
+	}
+
+	while (!(list_empty(&pshm_drv->rx_empty_list))) {
+		pbuf =
+			list_entry(pshm_drv->rx_empty_list.next,
+				struct buf_list, list);
+		list_del(&pbuf->list);
+		kfree(pbuf);
+	}
+
+	/* Destroy work queues. */
+	destroy_workqueue(pshm_drv->pshm_tx_workqueue);
+	destroy_workqueue(pshm_drv->pshm_rx_workqueue);
+
+	unregister_netdev(pshm_netdev);
+}