1 files changed, 404 insertions, 0 deletions
diff --git a/drivers/net/can/rx-offload.c b/drivers/net/can/rx-offload.c
new file mode 100644
index 000000000..5cf4171df
--- /dev/null
+++ b/drivers/net/can/rx-offload.c
@@ -0,0 +1,404 @@
+/*
+ * Copyright (c) 2014 David Jander, Protonic Holland
+ * Copyright (C) 2014-2017 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the version 2 of the GNU General Public License
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/can/dev.h>
+#include <linux/can/rx-offload.h>
+
+struct can_rx_offload_cb {
+	u32 timestamp;
+};
+
+static inline struct can_rx_offload_cb *can_rx_offload_get_cb(struct sk_buff *skb)
+{
+	BUILD_BUG_ON(sizeof(struct can_rx_offload_cb) > sizeof(skb->cb));
+
+	return (struct can_rx_offload_cb *)skb->cb;
+}
+
+static inline bool can_rx_offload_le(struct can_rx_offload *offload, unsigned int a, unsigned int b)
+{
+	if (offload->inc)
+		return a <= b;
+	else
+		return a >= b;
+}
+
+static inline unsigned int can_rx_offload_inc(struct can_rx_offload *offload, unsigned int *val)
+{
+	if (offload->inc)
+		return (*val)++;
+	else
+		return (*val)--;
+}
+
+static int can_rx_offload_napi_poll(struct napi_struct *napi, int quota)
+{
+	struct can_rx_offload *offload = container_of(napi, struct can_rx_offload, napi);
+	struct net_device *dev = offload->dev;
+	struct net_device_stats *stats = &dev->stats;
+	struct sk_buff *skb;
+	int work_done = 0;
+
+	while ((work_done < quota) &&
+	       (skb = skb_dequeue(&offload->skb_queue))) {
+		struct can_frame *cf = (struct can_frame *)skb->data;
+
+		work_done++;
+		stats->rx_packets++;
+		stats->rx_bytes += cf->can_dlc;
+		netif_receive_skb(skb);
+	}
+
+	if (work_done < quota) {
+		napi_complete_done(napi, work_done);
+
+		/* Check if there was another interrupt */
+		if (!skb_queue_empty(&offload->skb_queue))
+			napi_reschedule(&offload->napi);
+	}
+
+	can_led_event(offload->dev, CAN_LED_EVENT_RX);
+
+	return work_done;
+}
+
+static inline void __skb_queue_add_sort(struct sk_buff_head *head, struct sk_buff *new,
+					int (*compare)(struct sk_buff *a, struct sk_buff *b))
+{
+	struct sk_buff *pos, *insert = (struct sk_buff *)head;
+
+	skb_queue_reverse_walk(head, pos) {
+		const struct can_rx_offload_cb *cb_pos, *cb_new;
+
+		cb_pos = can_rx_offload_get_cb(pos);
+		cb_new = can_rx_offload_get_cb(new);
+
+		netdev_dbg(new->dev,
+			   "%s: pos=0x%08x, new=0x%08x, diff=%10d, queue_len=%d\n",
+			   __func__,
+			   cb_pos->timestamp, cb_new->timestamp,
+			   cb_new->timestamp - cb_pos->timestamp,
+			   skb_queue_len(head));
+
+		if (compare(pos, new) < 0)
+			continue;
+		insert = pos;
+		break;
+	}
+
+	__skb_queue_after(head, insert, new);
+}
+
+static int can_rx_offload_compare(struct sk_buff *a, struct sk_buff *b)
+{
+	const struct can_rx_offload_cb *cb_a, *cb_b;
+
+	cb_a = can_rx_offload_get_cb(a);
+	cb_b = can_rx_offload_get_cb(b);
+
+	/* Substract two u32 and return result as int, to keep
+	 * difference steady around the u32 overflow.
+	 */
+	return cb_b->timestamp - cb_a->timestamp;
+}
+
+/**
+ * can_rx_offload_offload_one() - Read one CAN frame from HW
+ * @offload: pointer to rx_offload context
+ * @n: number of mailbox to read
+ *
+ * The task of this function is to read a CAN frame from mailbox @n
+ * from the device and return the mailbox's content as a struct
+ * sk_buff.
+ *
+ * If the struct can_rx_offload::skb_queue exceeds the maximal queue
+ * length (struct can_rx_offload::skb_queue_len_max) or no skb can be
+ * allocated, the mailbox contents is discarded by reading it into an
+ * overflow buffer. This way the mailbox is marked as free by the
+ * driver.
+ *
+ * Return: A pointer to skb containing the CAN frame on success.
+ *
+ *         NULL if the mailbox @n is empty.
+ *
+ *         ERR_PTR() in case of an error
+ */
+static struct sk_buff *
+can_rx_offload_offload_one(struct can_rx_offload *offload, unsigned int n)
+{
+	struct sk_buff *skb = NULL, *skb_error = NULL;
+	struct can_rx_offload_cb *cb;
+	struct can_frame *cf;
+	int ret;
+
+	if (likely(skb_queue_len(&offload->skb_queue) <
+		   offload->skb_queue_len_max)) {
+		skb = alloc_can_skb(offload->dev, &cf);
+		if (unlikely(!skb))
+			skb_error = ERR_PTR(-ENOMEM);	/* skb alloc failed */
+	} else {
+		skb_error = ERR_PTR(-ENOBUFS);		/* skb_queue is full */
+	}
+
+	/* If queue is full or skb not available, drop by reading into
+	 * overflow buffer.
+	 */
+	if (unlikely(skb_error)) {
+		struct can_frame cf_overflow;
+		u32 timestamp;
+
+		ret = offload->mailbox_read(offload, &cf_overflow,
+					    &timestamp, n);
+
+		/* Mailbox was empty. */
+		if (unlikely(!ret))
+			return NULL;
+
+		/* Mailbox has been read and we're dropping it or
+		 * there was a problem reading the mailbox.
+		 *
+		 * Increment error counters in any case.
+		 */
+		offload->dev->stats.rx_dropped++;
+		offload->dev->stats.rx_fifo_errors++;
+
+		/* There was a problem reading the mailbox, propagate
+		 * error value.
+		 */
+		if (unlikely(ret < 0))
+			return ERR_PTR(ret);
+
+		return skb_error;
+	}
+
+	cb = can_rx_offload_get_cb(skb);
+	ret = offload->mailbox_read(offload, cf, &cb->timestamp, n);
+
+	/* Mailbox was empty. */
+	if (unlikely(!ret)) {
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	/* There was a problem reading the mailbox, propagate error value. */
+	if (unlikely(ret < 0)) {
+		kfree_skb(skb);
+
+		offload->dev->stats.rx_dropped++;
+		offload->dev->stats.rx_fifo_errors++;
+
+		return ERR_PTR(ret);
+	}
+
+	/* Mailbox was read. */
+	return skb;
+}
+
+int can_rx_offload_irq_offload_timestamp(struct can_rx_offload *offload, u64 pending)
+{
+	struct sk_buff_head skb_queue;
+	unsigned int i;
+
+	__skb_queue_head_init(&skb_queue);
+
+	for (i = offload->mb_first;
+	     can_rx_offload_le(offload, i, offload->mb_last);
+	     can_rx_offload_inc(offload, &i)) {
+		struct sk_buff *skb;
+
+		if (!(pending & BIT_ULL(i)))
+			continue;
+
+		skb = can_rx_offload_offload_one(offload, i);
+		if (IS_ERR_OR_NULL(skb))
+			continue;
+
+		__skb_queue_add_sort(&skb_queue, skb, can_rx_offload_compare);
+	}
+
+	if (!skb_queue_empty(&skb_queue)) {
+		unsigned long flags;
+		u32 queue_len;
+
+		spin_lock_irqsave(&offload->skb_queue.lock, flags);
+		skb_queue_splice_tail(&skb_queue, &offload->skb_queue);
+		spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
+
+		if ((queue_len = skb_queue_len(&offload->skb_queue)) >
+		    (offload->skb_queue_len_max / 8))
+			netdev_dbg(offload->dev, "%s: queue_len=%d\n",
+				   __func__, queue_len);
+
+		can_rx_offload_schedule(offload);
+	}
+
+	return skb_queue_len(&skb_queue);
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_timestamp);
+
+int can_rx_offload_irq_offload_fifo(struct can_rx_offload *offload)
+{
+	struct sk_buff *skb;
+	int received = 0;
+
+	while (1) {
+		skb = can_rx_offload_offload_one(offload, 0);
+		if (IS_ERR(skb))
+			continue;
+		if (!skb)
+			break;
+
+		skb_queue_tail(&offload->skb_queue, skb);
+		received++;
+	}
+
+	if (received)
+		can_rx_offload_schedule(offload);
+
+	return received;
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_irq_offload_fifo);
+
+int can_rx_offload_queue_sorted(struct can_rx_offload *offload,
+				struct sk_buff *skb, u32 timestamp)
+{
+	struct can_rx_offload_cb *cb;
+	unsigned long flags;
+
+	if (skb_queue_len(&offload->skb_queue) >
+	    offload->skb_queue_len_max) {
+		dev_kfree_skb_any(skb);
+		return -ENOBUFS;
+	}
+
+	cb = can_rx_offload_get_cb(skb);
+	cb->timestamp = timestamp;
+
+	spin_lock_irqsave(&offload->skb_queue.lock, flags);
+	__skb_queue_add_sort(&offload->skb_queue, skb, can_rx_offload_compare);
+	spin_unlock_irqrestore(&offload->skb_queue.lock, flags);
+
+	can_rx_offload_schedule(offload);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_queue_sorted);
+
+unsigned int can_rx_offload_get_echo_skb(struct can_rx_offload *offload,
+					 unsigned int idx, u32 timestamp)
+{
+	struct net_device *dev = offload->dev;
+	struct net_device_stats *stats = &dev->stats;
+	struct sk_buff *skb;
+	u8 len;
+	int err;
+
+	skb = __can_get_echo_skb(dev, idx, &len);
+	if (!skb)
+		return 0;
+
+	err = can_rx_offload_queue_sorted(offload, skb, timestamp);
+	if (err) {
+		stats->rx_errors++;
+		stats->tx_fifo_errors++;
+	}
+
+	return len;
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_get_echo_skb);
+
+int can_rx_offload_queue_tail(struct can_rx_offload *offload,
+			      struct sk_buff *skb)
+{
+	if (skb_queue_len(&offload->skb_queue) >
+	    offload->skb_queue_len_max) {
+		dev_kfree_skb_any(skb);
+		return -ENOBUFS;
+	}
+
+	skb_queue_tail(&offload->skb_queue, skb);
+	can_rx_offload_schedule(offload);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_queue_tail);
+
+static int can_rx_offload_init_queue(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
+{
+	offload->dev = dev;
+
+	/* Limit queue len to 4x the weight (rounted to next power of two) */
+	offload->skb_queue_len_max = 2 << fls(weight);
+	offload->skb_queue_len_max *= 4;
+	skb_queue_head_init(&offload->skb_queue);
+
+	can_rx_offload_reset(offload);
+	netif_napi_add(dev, &offload->napi, can_rx_offload_napi_poll, weight);
+
+	dev_dbg(dev->dev.parent, "%s: skb_queue_len_max=%d\n",
+		__func__, offload->skb_queue_len_max);
+
+	return 0;
+}
+
+int can_rx_offload_add_timestamp(struct net_device *dev, struct can_rx_offload *offload)
+{
+	unsigned int weight;
+
+	if (offload->mb_first > BITS_PER_LONG_LONG ||
+	    offload->mb_last > BITS_PER_LONG_LONG || !offload->mailbox_read)
+		return -EINVAL;
+
+	if (offload->mb_first < offload->mb_last) {
+		offload->inc = true;
+		weight = offload->mb_last - offload->mb_first;
+	} else {
+		offload->inc = false;
+		weight = offload->mb_first - offload->mb_last;
+	}
+
+	return can_rx_offload_init_queue(dev, offload, weight);
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_add_timestamp);
+
+int can_rx_offload_add_fifo(struct net_device *dev, struct can_rx_offload *offload, unsigned int weight)
+{
+	if (!offload->mailbox_read)
+		return -EINVAL;
+
+	return can_rx_offload_init_queue(dev, offload, weight);
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_add_fifo);
+
+void can_rx_offload_enable(struct can_rx_offload *offload)
+{
+	can_rx_offload_reset(offload);
+	napi_enable(&offload->napi);
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_enable);
+
+void can_rx_offload_del(struct can_rx_offload *offload)
+{
+	netif_napi_del(&offload->napi);
+	skb_queue_purge(&offload->skb_queue);
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_del);
+
+void can_rx_offload_reset(struct can_rx_offload *offload)
+{
+}
+EXPORT_SYMBOL_GPL(can_rx_offload_reset);