sfc: move common rx code

The moved code deals with managing rx buffers and queues.
A tiny bit of refactoring was required in other files to stitch the
code together.

Signed-off-by: Alexandru-Mihai Maftei <amaftei@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 375 insertions, 0 deletions

diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
new file mode 100644
index 000000000000..f4b5c3d828f6
--- /dev/null
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -0,0 +1,375 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/****************************************************************************
+ * Driver for Solarflare network controllers and boards
+ * Copyright 2018 Solarflare Communications Inc.
+ *
+ * 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, incorporated herein by reference.
+ */
+
+#include "net_driver.h"
+#include <linux/module.h>
+#include "efx.h"
+#include "nic.h"
+#include "rx_common.h"
+
+/* This is the percentage fill level below which new RX descriptors
+ * will be added to the RX descriptor ring.
+ */
+static unsigned int rx_refill_threshold;
+module_param(rx_refill_threshold, uint, 0444);
+MODULE_PARM_DESC(rx_refill_threshold,
+		 "RX descriptor ring refill threshold (%)");
+
+/* RX maximum head room required.
+ *
+ * This must be at least 1 to prevent overflow, plus one packet-worth
+ * to allow pipelined receives.
+ */
+#define EFX_RXD_HEAD_ROOM (1 + EFX_RX_MAX_FRAGS)
+
+static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue,
+			       struct efx_rx_buffer *rx_buf)
+{
+	/* Release the page reference we hold for the buffer. */
+	if (rx_buf->page)
+		put_page(rx_buf->page);
+
+	/* If this is the last buffer in a page, unmap and free it. */
+	if (rx_buf->flags & EFX_RX_BUF_LAST_IN_PAGE) {
+		efx_unmap_rx_buffer(rx_queue->efx, rx_buf);
+		efx_free_rx_buffers(rx_queue, rx_buf, 1);
+	}
+	rx_buf->page = NULL;
+}
+
+int efx_probe_rx_queue(struct efx_rx_queue *rx_queue)
+{
+	struct efx_nic *efx = rx_queue->efx;
+	unsigned int entries;
+	int rc;
+
+	/* Create the smallest power-of-two aligned ring */
+	entries = max(roundup_pow_of_two(efx->rxq_entries), EFX_MIN_DMAQ_SIZE);
+	EFX_WARN_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE);
+	rx_queue->ptr_mask = entries - 1;
+
+	netif_dbg(efx, probe, efx->net_dev,
+		  "creating RX queue %d size %#x mask %#x\n",
+		  efx_rx_queue_index(rx_queue), efx->rxq_entries,
+		  rx_queue->ptr_mask);
+
+	/* Allocate RX buffers */
+	rx_queue->buffer = kcalloc(entries, sizeof(*rx_queue->buffer),
+				   GFP_KERNEL);
+	if (!rx_queue->buffer)
+		return -ENOMEM;
+
+	rc = efx_nic_probe_rx(rx_queue);
+	if (rc) {
+		kfree(rx_queue->buffer);
+		rx_queue->buffer = NULL;
+	}
+
+	return rc;
+}
+
+void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
+{
+	unsigned int max_fill, trigger, max_trigger;
+	struct efx_nic *efx = rx_queue->efx;
+	int rc = 0;
+
+	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
+		  "initialising RX queue %d\n", efx_rx_queue_index(rx_queue));
+
+	/* Initialise ptr fields */
+	rx_queue->added_count = 0;
+	rx_queue->notified_count = 0;
+	rx_queue->removed_count = 0;
+	rx_queue->min_fill = -1U;
+	efx_init_rx_recycle_ring(rx_queue);
+
+	rx_queue->page_remove = 0;
+	rx_queue->page_add = rx_queue->page_ptr_mask + 1;
+	rx_queue->page_recycle_count = 0;
+	rx_queue->page_recycle_failed = 0;
+	rx_queue->page_recycle_full = 0;
+
+	/* Initialise limit fields */
+	max_fill = efx->rxq_entries - EFX_RXD_HEAD_ROOM;
+	max_trigger =
+		max_fill - efx->rx_pages_per_batch * efx->rx_bufs_per_page;
+	if (rx_refill_threshold != 0) {
+		trigger = max_fill * min(rx_refill_threshold, 100U) / 100U;
+		if (trigger > max_trigger)
+			trigger = max_trigger;
+	} else {
+		trigger = max_trigger;
+	}
+
+	rx_queue->max_fill = max_fill;
+	rx_queue->fast_fill_trigger = trigger;
+	rx_queue->refill_enabled = true;
+
+	/* Initialise XDP queue information */
+	rc = xdp_rxq_info_reg(&rx_queue->xdp_rxq_info, efx->net_dev,
+			      rx_queue->core_index);
+
+	if (rc) {
+		netif_err(efx, rx_err, efx->net_dev,
+			  "Failure to initialise XDP queue information rc=%d\n",
+			  rc);
+		efx->xdp_rxq_info_failed = true;
+	} else {
+		rx_queue->xdp_rxq_info_valid = true;
+	}
+
+	/* Set up RX descriptor ring */
+	efx_nic_init_rx(rx_queue);
+}
+
+void efx_fini_rx_queue(struct efx_rx_queue *rx_queue)
+{
+	struct efx_nic *efx = rx_queue->efx;
+	struct efx_rx_buffer *rx_buf;
+	int i;
+
+	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
+		  "shutting down RX queue %d\n", efx_rx_queue_index(rx_queue));
+
+	del_timer_sync(&rx_queue->slow_fill);
+
+	/* Release RX buffers from the current read ptr to the write ptr */
+	if (rx_queue->buffer) {
+		for (i = rx_queue->removed_count; i < rx_queue->added_count;
+		     i++) {
+			unsigned int index = i & rx_queue->ptr_mask;
+
+			rx_buf = efx_rx_buffer(rx_queue, index);
+			efx_fini_rx_buffer(rx_queue, rx_buf);
+		}
+	}
+
+	/* Unmap and release the pages in the recycle ring. Remove the ring. */
+	for (i = 0; i <= rx_queue->page_ptr_mask; i++) {
+		struct page *page = rx_queue->page_ring[i];
+		struct efx_rx_page_state *state;
+
+		if (page == NULL)
+			continue;
+
+		state = page_address(page);
+		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
+			       PAGE_SIZE << efx->rx_buffer_order,
+			       DMA_FROM_DEVICE);
+		put_page(page);
+	}
+	kfree(rx_queue->page_ring);
+	rx_queue->page_ring = NULL;
+
+	if (rx_queue->xdp_rxq_info_valid)
+		xdp_rxq_info_unreg(&rx_queue->xdp_rxq_info);
+
+	rx_queue->xdp_rxq_info_valid = false;
+}
+
+void efx_remove_rx_queue(struct efx_rx_queue *rx_queue)
+{
+	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
+		  "destroying RX queue %d\n", efx_rx_queue_index(rx_queue));
+
+	efx_nic_remove_rx(rx_queue);
+
+	kfree(rx_queue->buffer);
+	rx_queue->buffer = NULL;
+}
+
+/* Unmap a DMA-mapped page.  This function is only called for the final RX
+ * buffer in a page.
+ */
+void efx_unmap_rx_buffer(struct efx_nic *efx,
+			 struct efx_rx_buffer *rx_buf)
+{
+	struct page *page = rx_buf->page;
+
+	if (page) {
+		struct efx_rx_page_state *state = page_address(page);
+
+		dma_unmap_page(&efx->pci_dev->dev,
+			       state->dma_addr,
+			       PAGE_SIZE << efx->rx_buffer_order,
+			       DMA_FROM_DEVICE);
+	}
+}
+
+void efx_free_rx_buffers(struct efx_rx_queue *rx_queue,
+			 struct efx_rx_buffer *rx_buf,
+			 unsigned int num_bufs)
+{
+	do {
+		if (rx_buf->page) {
+			put_page(rx_buf->page);
+			rx_buf->page = NULL;
+		}
+		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
+	} while (--num_bufs);
+}
+
+void efx_rx_slow_fill(struct timer_list *t)
+{
+	struct efx_rx_queue *rx_queue = from_timer(rx_queue, t, slow_fill);
+
+	/* Post an event to cause NAPI to run and refill the queue */
+	efx_nic_generate_fill_event(rx_queue);
+	++rx_queue->slow_fill_count;
+}
+
+void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue)
+{
+	mod_timer(&rx_queue->slow_fill, jiffies + msecs_to_jiffies(10));
+}
+
+/* efx_init_rx_buffers - create EFX_RX_BATCH page-based RX buffers
+ *
+ * @rx_queue:		Efx RX queue
+ *
+ * This allocates a batch of pages, maps them for DMA, and populates
+ * struct efx_rx_buffers for each one. Return a negative error code or
+ * 0 on success. If a single page can be used for multiple buffers,
+ * then the page will either be inserted fully, or not at all.
+ */
+static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue, bool atomic)
+{
+	unsigned int page_offset, index, count;
+	struct efx_nic *efx = rx_queue->efx;
+	struct efx_rx_page_state *state;
+	struct efx_rx_buffer *rx_buf;
+	dma_addr_t dma_addr;
+	struct page *page;
+
+	count = 0;
+	do {
+		page = efx_reuse_page(rx_queue);
+		if (page == NULL) {
+			page = alloc_pages(__GFP_COMP |
+					   (atomic ? GFP_ATOMIC : GFP_KERNEL),
+					   efx->rx_buffer_order);
+			if (unlikely(page == NULL))
+				return -ENOMEM;
+			dma_addr =
+				dma_map_page(&efx->pci_dev->dev, page, 0,
+					     PAGE_SIZE << efx->rx_buffer_order,
+					     DMA_FROM_DEVICE);
+			if (unlikely(dma_mapping_error(&efx->pci_dev->dev,
+						       dma_addr))) {
+				__free_pages(page, efx->rx_buffer_order);
+				return -EIO;
+			}
+			state = page_address(page);
+			state->dma_addr = dma_addr;
+		} else {
+			state = page_address(page);
+			dma_addr = state->dma_addr;
+		}
+
+		dma_addr += sizeof(struct efx_rx_page_state);
+		page_offset = sizeof(struct efx_rx_page_state);
+
+		do {
+			index = rx_queue->added_count & rx_queue->ptr_mask;
+			rx_buf = efx_rx_buffer(rx_queue, index);
+			rx_buf->dma_addr = dma_addr + efx->rx_ip_align +
+					   XDP_PACKET_HEADROOM;
+			rx_buf->page = page;
+			rx_buf->page_offset = page_offset + efx->rx_ip_align +
+					      XDP_PACKET_HEADROOM;
+			rx_buf->len = efx->rx_dma_len;
+			rx_buf->flags = 0;
+			++rx_queue->added_count;
+			get_page(page);
+			dma_addr += efx->rx_page_buf_step;
+			page_offset += efx->rx_page_buf_step;
+		} while (page_offset + efx->rx_page_buf_step <= PAGE_SIZE);
+
+		rx_buf->flags = EFX_RX_BUF_LAST_IN_PAGE;
+	} while (++count < efx->rx_pages_per_batch);
+
+	return 0;
+}
+
+void efx_rx_config_page_split(struct efx_nic *efx)
+{
+	efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align +
+				      XDP_PACKET_HEADROOM,
+				      EFX_RX_BUF_ALIGNMENT);
+	efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
+		((PAGE_SIZE - sizeof(struct efx_rx_page_state)) /
+		efx->rx_page_buf_step);
+	efx->rx_buffer_truesize = (PAGE_SIZE << efx->rx_buffer_order) /
+		efx->rx_bufs_per_page;
+	efx->rx_pages_per_batch = DIV_ROUND_UP(EFX_RX_PREFERRED_BATCH,
+					       efx->rx_bufs_per_page);
+}
+
+/* efx_fast_push_rx_descriptors - push new RX descriptors quickly
+ * @rx_queue:		RX descriptor queue
+ *
+ * This will aim to fill the RX descriptor queue up to
+ * @rx_queue->@max_fill. If there is insufficient atomic
+ * memory to do so, a slow fill will be scheduled.
+ *
+ * The caller must provide serialisation (none is used here). In practise,
+ * this means this function must run from the NAPI handler, or be called
+ * when NAPI is disabled.
+ */
+void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue, bool atomic)
+{
+	struct efx_nic *efx = rx_queue->efx;
+	unsigned int fill_level, batch_size;
+	int space, rc = 0;
+
+	if (!rx_queue->refill_enabled)
+		return;
+
+	/* Calculate current fill level, and exit if we don't need to fill */
+	fill_level = (rx_queue->added_count - rx_queue->removed_count);
+	EFX_WARN_ON_ONCE_PARANOID(fill_level > rx_queue->efx->rxq_entries);
+	if (fill_level >= rx_queue->fast_fill_trigger)
+		goto out;
+
+	/* Record minimum fill level */
+	if (unlikely(fill_level < rx_queue->min_fill)) {
+		if (fill_level)
+			rx_queue->min_fill = fill_level;
+	}
+
+	batch_size = efx->rx_pages_per_batch * efx->rx_bufs_per_page;
+	space = rx_queue->max_fill - fill_level;
+	EFX_WARN_ON_ONCE_PARANOID(space < batch_size);
+
+	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
+		   "RX queue %d fast-filling descriptor ring from"
+		   " level %d to level %d\n",
+		   efx_rx_queue_index(rx_queue), fill_level,
+		   rx_queue->max_fill);
+
+	do {
+		rc = efx_init_rx_buffers(rx_queue, atomic);
+		if (unlikely(rc)) {
+			/* Ensure that we don't leave the rx queue empty */
+			efx_schedule_slow_fill(rx_queue);
+			goto out;
+		}
+	} while ((space -= batch_size) >= batch_size);
+
+	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
+		   "RX queue %d fast-filled descriptor ring "
+		   "to level %d\n", efx_rx_queue_index(rx_queue),
+		   rx_queue->added_count - rx_queue->removed_count);
+
+ out:
+	if (rx_queue->notified_count != rx_queue->added_count)
+		efx_nic_notify_rx_desc(rx_queue);
+}