net: ti: icssg-prueth: Use page_pool API for RX buffer allocation

This is to prepare for native XDP support.

The page pool API is more faster in allocating pages than
__alloc_skb(). Drawback is that it works at PAGE_SIZE granularity
so we are not efficient in memory usage.
i.e. we are using PAGE_SIZE (4KB) memory for 1.5KB max packet size.

Signed-off-by: Roger Quadros <[email protected]>
Signed-off-by: MD Danish Anwar <[email protected]>
Signed-off-by: Meghana Malladi <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: rogerq

drivers/net/ethernet/ti/Kconfig

@@ -205,6 +205,7 @@ config TI_ICSSG_PRUETH_SR1
 	select PHYLIB
 	select TI_ICSS_IEP
 	select TI_K3_CPPI_DESC_POOL
+	select PAGE_POOL
 	depends on PRU_REMOTEPROC
 	depends on NET_SWITCHDEV
 	depends on ARCH_K3 && OF && TI_K3_UDMA_GLUE_LAYER

drivers/net/ethernet/ti/icssg/icssg_common.c

@@ -45,6 +45,11 @@ void prueth_cleanup_rx_chns(struct prueth_emac *emac,
 			    struct prueth_rx_chn *rx_chn,
 			    int max_rflows)
 {
+	if (rx_chn->pg_pool) {
+		page_pool_destroy(rx_chn->pg_pool);
+		rx_chn->pg_pool = NULL;
+	}
+
 	if (rx_chn->desc_pool)
 		k3_cppi_desc_pool_destroy(rx_chn->desc_pool);
 
@@ -461,43 +466,36 @@ int prueth_init_rx_chns(struct prueth_emac *emac,
 }
 EXPORT_SYMBOL_GPL(prueth_init_rx_chns);
 
-int prueth_dma_rx_push(struct prueth_emac *emac,
-		       struct sk_buff *skb,
-		       struct prueth_rx_chn *rx_chn)
+int prueth_dma_rx_push_mapped(struct prueth_emac *emac,
+			      struct prueth_rx_chn *rx_chn,
+			      struct page *page, u32 buf_len)
 {
 	struct net_device *ndev = emac->ndev;
 	struct cppi5_host_desc_t *desc_rx;
-	u32 pkt_len = skb_tailroom(skb);
 	dma_addr_t desc_dma;
 	dma_addr_t buf_dma;
 	void **swdata;
 
+	buf_dma = page_pool_get_dma_addr(page) + PRUETH_HEADROOM;
 	desc_rx = k3_cppi_desc_pool_alloc(rx_chn->desc_pool);
 	if (!desc_rx) {
 		netdev_err(ndev, "rx push: failed to allocate descriptor\n");
 		return -ENOMEM;
 	}
 	desc_dma = k3_cppi_desc_pool_virt2dma(rx_chn->desc_pool, desc_rx);
 
-	buf_dma = dma_map_single(rx_chn->dma_dev, skb->data, pkt_len, DMA_FROM_DEVICE);
-	if (unlikely(dma_mapping_error(rx_chn->dma_dev, buf_dma))) {
-		k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
-		netdev_err(ndev, "rx push: failed to map rx pkt buffer\n");
-		return -EINVAL;
-	}
-
 	cppi5_hdesc_init(desc_rx, CPPI5_INFO0_HDESC_EPIB_PRESENT,
 			 PRUETH_NAV_PS_DATA_SIZE);
 	k3_udma_glue_rx_dma_to_cppi5_addr(rx_chn->rx_chn, &buf_dma);
-	cppi5_hdesc_attach_buf(desc_rx, buf_dma, skb_tailroom(skb), buf_dma, skb_tailroom(skb));
+	cppi5_hdesc_attach_buf(desc_rx, buf_dma, buf_len, buf_dma, buf_len);
 
 	swdata = cppi5_hdesc_get_swdata(desc_rx);
-	*swdata = skb;
+	*swdata = page;
 
-	return k3_udma_glue_push_rx_chn(rx_chn->rx_chn, 0,
+	return k3_udma_glue_push_rx_chn(rx_chn->rx_chn, PRUETH_RX_FLOW_DATA,
 					desc_rx, desc_dma);
 }
-EXPORT_SYMBOL_GPL(prueth_dma_rx_push);
+EXPORT_SYMBOL_GPL(prueth_dma_rx_push_mapped);
 
 u64 icssg_ts_to_ns(u32 hi_sw, u32 hi, u32 lo, u32 cycle_time_ns)
 {
@@ -541,12 +539,16 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
 	u32 buf_dma_len, pkt_len, port_id = 0;
 	struct net_device *ndev = emac->ndev;
 	struct cppi5_host_desc_t *desc_rx;
-	struct sk_buff *skb, *new_skb;
 	dma_addr_t desc_dma, buf_dma;
+	struct page *page, *new_page;
+	struct page_pool *pool;
+	struct sk_buff *skb;
 	void **swdata;
 	u32 *psdata;
+	void *pa;
 	int ret;
 
+	pool = rx_chn->pg_pool;
 	ret = k3_udma_glue_pop_rx_chn(rx_chn->rx_chn, flow_id, &desc_dma);
 	if (ret) {
 		if (ret != -ENODATA)
@@ -558,48 +560,61 @@ static int emac_rx_packet(struct prueth_emac *emac, u32 flow_id)
 		return 0;
 
 	desc_rx = k3_cppi_desc_pool_dma2virt(rx_chn->desc_pool, desc_dma);
-
 	swdata = cppi5_hdesc_get_swdata(desc_rx);
-	skb = *swdata;
-
-	psdata = cppi5_hdesc_get_psdata(desc_rx);
-	/* RX HW timestamp */
-	if (emac->rx_ts_enabled)
-		emac_rx_timestamp(emac, skb, psdata);
-
+	page = *swdata;
+	page_pool_dma_sync_for_cpu(pool, page, 0, PAGE_SIZE);
 	cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
 	k3_udma_glue_rx_cppi5_to_dma_addr(rx_chn->rx_chn, &buf_dma);
 	pkt_len = cppi5_hdesc_get_pktlen(desc_rx);
 	/* firmware adds 4 CRC bytes, strip them */
 	pkt_len -= 4;
 	cppi5_desc_get_tags_ids(&desc_rx->hdr, &port_id, NULL);
 
-	dma_unmap_single(rx_chn->dma_dev, buf_dma, buf_dma_len, DMA_FROM_DEVICE);
 	k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
 
-	skb->dev = ndev;
-	new_skb = netdev_alloc_skb_ip_align(ndev, PRUETH_MAX_PKT_SIZE);
 	/* if allocation fails we drop the packet but push the
-	 * descriptor back to the ring with old skb to prevent a stall
+	 * descriptor back to the ring with old page to prevent a stall
 	 */
-	if (!new_skb) {
+	new_page = page_pool_dev_alloc_pages(pool);
+	if (unlikely(!new_page)) {
+		new_page = page;
 		ndev->stats.rx_dropped++;
-		new_skb = skb;
-	} else {
-		/* send the filled skb up the n/w stack */
-		skb_put(skb, pkt_len);
-		if (emac->prueth->is_switch_mode)
-			skb->offload_fwd_mark = emac->offload_fwd_mark;
-		skb->protocol = eth_type_trans(skb, ndev);
-		napi_gro_receive(&emac->napi_rx, skb);
-		ndev->stats.rx_bytes += pkt_len;
-		ndev->stats.rx_packets++;
+		goto requeue;
+	}
+
+	/* prepare skb and send to n/w stack */
+	pa = page_address(page);
+	skb = napi_build_skb(pa, PAGE_SIZE);
+	if (!skb) {
+		ndev->stats.rx_dropped++;
+		page_pool_recycle_direct(pool, page);
+		goto requeue;
 	}
 
+	skb_reserve(skb, PRUETH_HEADROOM);
+	skb_put(skb, pkt_len);
+	skb->dev = ndev;
+
+	psdata = cppi5_hdesc_get_psdata(desc_rx);
+	/* RX HW timestamp */
+	if (emac->rx_ts_enabled)
+		emac_rx_timestamp(emac, skb, psdata);
+
+	if (emac->prueth->is_switch_mode)
+		skb->offload_fwd_mark = emac->offload_fwd_mark;
+	skb->protocol = eth_type_trans(skb, ndev);
+
+	skb_mark_for_recycle(skb);
+	napi_gro_receive(&emac->napi_rx, skb);
+	ndev->stats.rx_bytes += pkt_len;
+	ndev->stats.rx_packets++;
+
+requeue:
 	/* queue another RX DMA */
-	ret = prueth_dma_rx_push(emac, new_skb, &emac->rx_chns);
+	ret = prueth_dma_rx_push_mapped(emac, &emac->rx_chns, new_page,
+					PRUETH_MAX_PKT_SIZE);
 	if (WARN_ON(ret < 0)) {
-		dev_kfree_skb_any(new_skb);
+		page_pool_recycle_direct(pool, new_page);
 		ndev->stats.rx_errors++;
 		ndev->stats.rx_dropped++;
 	}
@@ -611,22 +626,16 @@ static void prueth_rx_cleanup(void *data, dma_addr_t desc_dma)
 {
 	struct prueth_rx_chn *rx_chn = data;
 	struct cppi5_host_desc_t *desc_rx;
-	struct sk_buff *skb;
-	dma_addr_t buf_dma;
-	u32 buf_dma_len;
+	struct page_pool *pool;
+	struct page *page;
 	void **swdata;
 
+	pool = rx_chn->pg_pool;
 	desc_rx = k3_cppi_desc_pool_dma2virt(rx_chn->desc_pool, desc_dma);
 	swdata = cppi5_hdesc_get_swdata(desc_rx);
-	skb = *swdata;
-	cppi5_hdesc_get_obuf(desc_rx, &buf_dma, &buf_dma_len);
-	k3_udma_glue_rx_cppi5_to_dma_addr(rx_chn->rx_chn, &buf_dma);
-
-	dma_unmap_single(rx_chn->dma_dev, buf_dma, buf_dma_len,
-			 DMA_FROM_DEVICE);
+	page = *swdata;
+	page_pool_recycle_direct(pool, page);
 	k3_cppi_desc_pool_free(rx_chn->desc_pool, desc_rx);
-
-	dev_kfree_skb_any(skb);
 }
 
 static int prueth_tx_ts_cookie_get(struct prueth_emac *emac)
@@ -907,29 +916,71 @@ int icssg_napi_rx_poll(struct napi_struct *napi_rx, int budget)
 }
 EXPORT_SYMBOL_GPL(icssg_napi_rx_poll);
 
+static struct page_pool *prueth_create_page_pool(struct prueth_emac *emac,
+						 struct device *dma_dev,
+						 int size)
+{
+	struct page_pool_params pp_params = { 0 };
+	struct page_pool *pool;
+
+	pp_params.order = 0;
+	pp_params.flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV;
+	pp_params.pool_size = size;
+	pp_params.nid = dev_to_node(emac->prueth->dev);
+	pp_params.dma_dir = DMA_BIDIRECTIONAL;
+	pp_params.dev = dma_dev;
+	pp_params.napi = &emac->napi_rx;
+	pp_params.max_len = PAGE_SIZE;
+
+	pool = page_pool_create(&pp_params);
+	if (IS_ERR(pool))
+		netdev_err(emac->ndev, "cannot create rx page pool\n");
+
+	return pool;
+}
+
 int prueth_prepare_rx_chan(struct prueth_emac *emac,
 			   struct prueth_rx_chn *chn,
 			   int buf_size)
 {
-	struct sk_buff *skb;
+	struct page_pool *pool;
+	struct page *page;
 	int i, ret;
 
+	pool = prueth_create_page_pool(emac, chn->dma_dev, chn->descs_num);
+	if (IS_ERR(pool))
+		return PTR_ERR(pool);
+
+	chn->pg_pool = pool;
+
 	for (i = 0; i < chn->descs_num; i++) {
-		skb = __netdev_alloc_skb_ip_align(NULL, buf_size, GFP_KERNEL);
-		if (!skb)
-			return -ENOMEM;
+		/* NOTE: we're not using memory efficiently here.
+		 * 1 full page (4KB?) used here instead of
+		 * PRUETH_MAX_PKT_SIZE (~1.5KB?)
+		 */
+		page = page_pool_dev_alloc_pages(pool);
+		if (!page) {
+			netdev_err(emac->ndev, "couldn't allocate rx page\n");
+			ret = -ENOMEM;
+			goto recycle_alloc_pg;
+		}
 
-		ret = prueth_dma_rx_push(emac, skb, chn);
+		ret = prueth_dma_rx_push_mapped(emac, chn, page, buf_size);
 		if (ret < 0) {
 			netdev_err(emac->ndev,
-				   "cannot submit skb for rx chan %s ret %d\n",
+				   "cannot submit page for rx chan %s ret %d\n",
 				   chn->name, ret);
-			kfree_skb(skb);
-			return ret;
+			page_pool_recycle_direct(pool, page);
+			goto recycle_alloc_pg;
 		}
 	}
 
 	return 0;
+
+recycle_alloc_pg:
+	prueth_reset_rx_chan(&emac->rx_chns, PRUETH_MAX_RX_FLOWS, false);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(prueth_prepare_rx_chan);
 
@@ -958,6 +1009,9 @@ void prueth_reset_rx_chan(struct prueth_rx_chn *chn,
 					  prueth_rx_cleanup, !!i);
 	if (disable)
 		k3_udma_glue_disable_rx_chn(chn->rx_chn);
+
+	page_pool_destroy(chn->pg_pool);
+	chn->pg_pool = NULL;
 }
 EXPORT_SYMBOL_GPL(prueth_reset_rx_chan);
 

drivers/net/ethernet/ti/icssg/icssg_prueth.h

@@ -33,6 +33,8 @@
 #include <linux/dma/k3-udma-glue.h>
 
 #include <net/devlink.h>
+#include <net/xdp.h>
+#include <net/page_pool/helpers.h>
 
 #include "icssg_config.h"
 #include "icss_iep.h"
@@ -131,6 +133,7 @@ struct prueth_rx_chn {
 	u32 descs_num;
 	unsigned int irq[ICSSG_MAX_RFLOWS];	/* separate irq per flow */
 	char name[32];
+	struct page_pool *pg_pool;
 };
 
 /* There are 4 Tx DMA channels, but the highest priority is CH3 (thread 3)
@@ -210,6 +213,10 @@ struct prueth_emac {
 	struct netdev_hw_addr_list vlan_mcast_list[MAX_VLAN_ID];
 };
 
+/* The buf includes headroom compatible with both skb and xdpf */
+#define PRUETH_HEADROOM_NA (max(XDP_PACKET_HEADROOM, NET_SKB_PAD) + NET_IP_ALIGN)
+#define PRUETH_HEADROOM  ALIGN(PRUETH_HEADROOM_NA, sizeof(long))
+
 /**
  * struct prueth_pdata - PRUeth platform data
  * @fdqring_mode: Free desc queue mode
@@ -410,9 +417,10 @@ int prueth_init_rx_chns(struct prueth_emac *emac,
 			struct prueth_rx_chn *rx_chn,
 			char *name, u32 max_rflows,
 			u32 max_desc_num);
-int prueth_dma_rx_push(struct prueth_emac *emac,
-		       struct sk_buff *skb,
-		       struct prueth_rx_chn *rx_chn);
+int prueth_dma_rx_push_mapped(struct prueth_emac *emac,
+			      struct prueth_rx_chn *rx_chn,
+			      struct page *page, u32 buf_len);
+unsigned int prueth_rxbuf_total_len(unsigned int len);
 void emac_rx_timestamp(struct prueth_emac *emac,
 		       struct sk_buff *skb, u32 *psdata);
 enum netdev_tx icssg_ndo_start_xmit(struct sk_buff *skb, struct net_device *ndev);