net: wwan: t7xx: Add NAPI support

Replace the work queue based RX flow with a NAPI implementation
Remove rx_thread and dpmaif_rxq_work.
Enable GRO on RX path.
Introduce dummy network device. its responsibility is
    - Binds one NAPI object for each DL HW queue and acts as
      the agent of all those network devices.
    - Use NAPI object to poll DL packets.
    - Helps to dispatch each packet to the network interface.
Signed-off-by: Haijun Liu <haijun.liu@mediatek.com>
Co-developed-by: Sreehari Kancharla <sreehari.kancharla@linux.intel.com>
Signed-off-by: Sreehari Kancharla <sreehari.kancharla@linux.intel.com>
Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
Acked-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Acked-by: M Chetan Kumar <m.chetan.kumar@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wwan/t7xx/t7xx_hif_dpmaif.h

@@ -20,6 +20,7 @@
 
 #include <linux/bitmap.h>
 #include <linux/mm_types.h>
+#include <linux/netdevice.h>
 #include <linux/sched.h>
 #include <linux/skbuff.h>
 #include <linux/spinlock.h>
@@ -109,20 +110,14 @@ struct dpmaif_rx_queue {
 	struct dpmaif_bat_request *bat_req;
 	struct dpmaif_bat_request *bat_frag;
 
-	wait_queue_head_t	rx_wq;
-	struct task_struct	*rx_thread;
-	struct sk_buff_head	skb_list;
-	unsigned int		skb_list_max_len;
-
-	struct workqueue_struct	*worker;
-	struct work_struct	dpmaif_rxq_work;
-
 	atomic_t		rx_processing;
 
 	struct dpmaif_ctrl	*dpmaif_ctrl;
 	unsigned int		expect_pit_seq;
 	unsigned int		pit_remain_release_cnt;
 	struct dpmaif_cur_rx_skb_info rx_data_info;
+	struct napi_struct	napi;
+	bool			sleep_lock_pending;
 };
 
 struct dpmaif_tx_queue {
@@ -168,7 +163,8 @@ enum dpmaif_txq_state {
 struct dpmaif_callbacks {
 	void (*state_notify)(struct t7xx_pci_dev *t7xx_dev,
 			     enum dpmaif_txq_state state, int txq_number);
-	void (*recv_skb)(struct t7xx_pci_dev *t7xx_dev, struct sk_buff *skb);
+	void (*recv_skb)(struct t7xx_ccmni_ctrl *ccmni_ctlb, struct sk_buff *skb,
+			 struct napi_struct *napi);
 };
 
 struct dpmaif_ctrl {

drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.h

@@ -112,5 +112,6 @@ int t7xx_dpmaif_bat_alloc(const struct dpmaif_ctrl *dpmaif_ctrl, struct dpmaif_b
 			  const enum bat_type buf_type);
 void t7xx_dpmaif_bat_free(const struct dpmaif_ctrl *dpmaif_ctrl,
 			  struct dpmaif_bat_request *bat_req);
+int t7xx_dpmaif_napi_rx_poll(struct napi_struct *napi, const int budget);
 
 #endif /* __T7XX_HIF_DPMA_RX_H__ */

drivers/net/wwan/t7xx/t7xx_netdev.c

@@ -22,6 +22,7 @@
 #include <linux/gfp.h>
 #include <linux/if_arp.h>
 #include <linux/if_ether.h>
+#include <linux/ip.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/netdev_features.h>
@@ -29,6 +30,7 @@
 #include <linux/skbuff.h>
 #include <linux/types.h>
 #include <linux/wwan.h>
+#include <net/ipv6.h>
 #include <net/pkt_sched.h>
 
 #include "t7xx_hif_dpmaif_rx.h"
@@ -39,13 +41,47 @@
 #include "t7xx_state_monitor.h"
 
 #define IP_MUX_SESSION_DEFAULT	0
+#define SBD_PACKET_TYPE_MASK	GENMASK(7, 4)
+
+static void t7xx_ccmni_enable_napi(struct t7xx_ccmni_ctrl *ctlb)
+{
+	int i;
+
+	if (ctlb->is_napi_en)
+		return;
+
+	for (i = 0; i < RXQ_NUM; i++) {
+		napi_enable(ctlb->napi[i]);
+		napi_schedule(ctlb->napi[i]);
+	}
+	ctlb->is_napi_en = true;
+}
+
+static void t7xx_ccmni_disable_napi(struct t7xx_ccmni_ctrl *ctlb)
+{
+	int i;
+
+	if (!ctlb->is_napi_en)
+		return;
+
+	for (i = 0; i < RXQ_NUM; i++) {
+		napi_synchronize(ctlb->napi[i]);
+		napi_disable(ctlb->napi[i]);
+	}
+
+	ctlb->is_napi_en = false;
+}
 
 static int t7xx_ccmni_open(struct net_device *dev)
 {
 	struct t7xx_ccmni *ccmni = wwan_netdev_drvpriv(dev);
+	struct t7xx_ccmni_ctrl *ccmni_ctl = ccmni->ctlb;
 
 	netif_carrier_on(dev);
 	netif_tx_start_all_queues(dev);
+	if (!atomic_fetch_inc(&ccmni_ctl->napi_usr_refcnt))
+		t7xx_ccmni_enable_napi(ccmni_ctl);
+
 	atomic_inc(&ccmni->usage);
 	return 0;
 }
@@ -53,8 +89,12 @@ static int t7xx_ccmni_open(struct net_device *dev)
 static int t7xx_ccmni_close(struct net_device *dev)
 {
 	struct t7xx_ccmni *ccmni = wwan_netdev_drvpriv(dev);
+	struct t7xx_ccmni_ctrl *ccmni_ctl = ccmni->ctlb;
 
 	atomic_dec(&ccmni->usage);
+	if (atomic_dec_and_test(&ccmni_ctl->napi_usr_refcnt))
+		t7xx_ccmni_disable_napi(ccmni_ctl);
+
 	netif_carrier_off(dev);
 	netif_tx_disable(dev);
 	return 0;
@@ -127,6 +167,9 @@ static void t7xx_ccmni_start(struct t7xx_ccmni_ctrl *ctlb)
 			netif_carrier_on(ccmni->dev);
 		}
 	}
+
+	if (atomic_read(&ctlb->napi_usr_refcnt))
+		t7xx_ccmni_enable_napi(ctlb);
 }
 
 static void t7xx_ccmni_pre_stop(struct t7xx_ccmni_ctrl *ctlb)
@@ -149,6 +192,9 @@ static void t7xx_ccmni_post_stop(struct t7xx_ccmni_ctrl *ctlb)
 	struct t7xx_ccmni *ccmni;
 	int i;
 
+	if (atomic_read(&ctlb->napi_usr_refcnt))
+		t7xx_ccmni_disable_napi(ctlb);
+
 	for (i = 0; i < ctlb->nic_dev_num; i++) {
 		ccmni = ctlb->ccmni_inst[i];
 		if (!ccmni)
@@ -183,6 +229,9 @@ static void t7xx_ccmni_wwan_setup(struct net_device *dev)
 	dev->features |= NETIF_F_RXCSUM;
 	dev->hw_features |= NETIF_F_RXCSUM;
 
+	dev->features |= NETIF_F_GRO;
+	dev->hw_features |= NETIF_F_GRO;
+
 	dev->needs_free_netdev = true;
 
 	dev->type = ARPHRD_NONE;
@@ -190,6 +239,34 @@ static void t7xx_ccmni_wwan_setup(struct net_device *dev)
 	dev->netdev_ops = &ccmni_netdev_ops;
 }
 
+static void t7xx_init_netdev_napi(struct t7xx_ccmni_ctrl *ctlb)
+{
+	int i;
+
+	/* one HW, but shared with multiple net devices,
+	 * so add a dummy device for NAPI.
+	 */
+	init_dummy_netdev(&ctlb->dummy_dev);
+	atomic_set(&ctlb->napi_usr_refcnt, 0);
+	ctlb->is_napi_en = false;
+
+	for (i = 0; i < RXQ_NUM; i++) {
+		ctlb->napi[i] = &ctlb->hif_ctrl->rxq[i].napi;
+		netif_napi_add_weight(&ctlb->dummy_dev, ctlb->napi[i], t7xx_dpmaif_napi_rx_poll,
+				      NIC_NAPI_POLL_BUDGET);
+	}
+}
+
+static void t7xx_uninit_netdev_napi(struct t7xx_ccmni_ctrl *ctlb)
+{
+	int i;
+
+	for (i = 0; i < RXQ_NUM; i++) {
+		netif_napi_del(ctlb->napi[i]);
+		ctlb->napi[i] = NULL;
+	}
+}
+
 static int t7xx_ccmni_wwan_newlink(void *ctxt, struct net_device *dev, u32 if_id,
 				   struct netlink_ext_ack *extack)
 {
@@ -311,7 +388,8 @@ static void init_md_status_notifier(struct t7xx_pci_dev *t7xx_dev)
 	t7xx_fsm_notifier_register(t7xx_dev->md, md_status_notifier);
 }
 
-static void t7xx_ccmni_recv_skb(struct t7xx_pci_dev *t7xx_dev, struct sk_buff *skb)
+static void t7xx_ccmni_recv_skb(struct t7xx_ccmni_ctrl *ccmni_ctlb, struct sk_buff *skb,
+				struct napi_struct *napi)
 {
 	struct t7xx_skb_cb *skb_cb;
 	struct net_device *net_dev;
@@ -321,23 +399,22 @@ static void t7xx_ccmni_recv_skb(struct t7xx_pci_dev *t7xx_dev, struct sk_buff *s
 
 	skb_cb = T7XX_SKB_CB(skb);
 	netif_id = skb_cb->netif_idx;
-	ccmni = t7xx_dev->ccmni_ctlb->ccmni_inst[netif_id];
+	ccmni = ccmni_ctlb->ccmni_inst[netif_id];
 	if (!ccmni) {
 		dev_kfree_skb(skb);
 		return;
 	}
 
 	net_dev = ccmni->dev;
-	skb->dev = net_dev;
-
 	pkt_type = skb_cb->rx_pkt_type;
+	skb->dev = net_dev;
 	if (pkt_type == PKT_TYPE_IP6)
 		skb->protocol = htons(ETH_P_IPV6);
 	else
 		skb->protocol = htons(ETH_P_IP);
 
 	skb_len = skb->len;
-	netif_rx(skb);
+	napi_gro_receive(napi, skb);
 	net_dev->stats.rx_packets++;
 	net_dev->stats.rx_bytes += skb_len;
 }
@@ -404,6 +481,7 @@ int t7xx_ccmni_init(struct t7xx_pci_dev *t7xx_dev)
 	if (!ctlb->hif_ctrl)
 		return -ENOMEM;
 
+	t7xx_init_netdev_napi(ctlb);
 	init_md_status_notifier(t7xx_dev);
 	return 0;
 }
@@ -419,5 +497,6 @@ void t7xx_ccmni_exit(struct t7xx_pci_dev *t7xx_dev)
 		ctlb->wwan_is_registered = false;
 	}
 
+	t7xx_uninit_netdev_napi(ctlb);
 	t7xx_dpmaif_hif_exit(ctlb->hif_ctrl);
 }

drivers/net/wwan/t7xx/t7xx_netdev.h

@@ -30,6 +30,7 @@
 
 #define CCMNI_NETDEV_WDT_TO		(1 * HZ)
 #define CCMNI_MTU_MAX			3000
+#define NIC_NAPI_POLL_BUDGET		128
 
 struct t7xx_ccmni {
 	u8				index;
@@ -47,6 +48,10 @@ struct t7xx_ccmni_ctrl {
 	unsigned int			md_sta;
 	struct t7xx_fsm_notifier	md_status_notify;
 	bool				wwan_is_registered;
+	struct net_device		dummy_dev;
+	struct napi_struct		*napi[RXQ_NUM];
+	atomic_t			napi_usr_refcnt;
+	bool				is_napi_en;
 };
 
 int t7xx_ccmni_init(struct t7xx_pci_dev *t7xx_dev);