text: /*
   * aQuantia Corporation Network Driver
   * Copyright (C) 2014-2017 aQuantia Corporation. All rights reserved
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   */
  
  /* File aq_ring.c: Definition of functions for Rx/Tx rings. */
  
  #include "aq_ring.h"
  #include "aq_nic.h"
  #include "aq_hw.h"
  
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  
  static struct aq_ring_s *aq_ring_alloc(struct aq_ring_s *self,
  				       struct aq_nic_s *aq_nic)
  {
  	int err = 0;
  
  	self->buff_ring =
  		kcalloc(self->size, sizeof(struct aq_ring_buff_s), GFP_KERNEL);
  
  	if (!self->buff_ring) {
  		err = -ENOMEM;
  		goto err_exit;
  	}
  	self->dx_ring = dma_alloc_coherent(aq_nic_get_dev(aq_nic),
  						self->size * self->dx_size,
  						&self->dx_ring_pa, GFP_KERNEL);
  	if (!self->dx_ring) {
  		err = -ENOMEM;
  		goto err_exit;
  	}
  
  err_exit:
  	if (err < 0) {
  		aq_ring_free(self);
  		self = NULL;
  	}
  	return self;
  }
  
  struct aq_ring_s *aq_ring_tx_alloc(struct aq_ring_s *self,
  				   struct aq_nic_s *aq_nic,
  				   unsigned int idx,
  				   struct aq_nic_cfg_s *aq_nic_cfg)
  {
  	int err = 0;
  
  	self->aq_nic = aq_nic;
  	self->idx = idx;
  	self->size = aq_nic_cfg->txds;
  	self->dx_size = aq_nic_cfg->aq_hw_caps->txd_size;
  
  	self = aq_ring_alloc(self, aq_nic);
  	if (!self) {
  		err = -ENOMEM;
  		goto err_exit;
  	}
  
  err_exit:
  	if (err < 0) {
  		aq_ring_free(self);
  		self = NULL;
  	}
  	return self;
  }
  
  struct aq_ring_s *aq_ring_rx_alloc(struct aq_ring_s *self,
  				   struct aq_nic_s *aq_nic,
  				   unsigned int idx,
  				   struct aq_nic_cfg_s *aq_nic_cfg)
  {
  	int err = 0;
  
  	self->aq_nic = aq_nic;
  	self->idx = idx;
  	self->size = aq_nic_cfg->rxds;
  	self->dx_size = aq_nic_cfg->aq_hw_caps->rxd_size;
  
  	self = aq_ring_alloc(self, aq_nic);
  	if (!self) {
  		err = -ENOMEM;
  		goto err_exit;
  	}
  
  err_exit:
  	if (err < 0) {
  		aq_ring_free(self);
  		self = NULL;
  	}
  	return self;
  }
  
  int aq_ring_init(struct aq_ring_s *self)
  {
  	self->hw_head = 0;
  	self->sw_head = 0;
  	self->sw_tail = 0;
  	return 0;
  }
  
  static inline bool aq_ring_dx_in_range(unsigned int h, unsigned int i,
  				       unsigned int t)
  {
  	return (h < t) ? ((h < i) && (i < t)) : ((h < i) || (i < t));
  }
  
  void aq_ring_update_queue_state(struct aq_ring_s *ring)
  {
  	if (aq_ring_avail_dx(ring) <= AQ_CFG_SKB_FRAGS_MAX)
  		aq_ring_queue_stop(ring);
  	else if (aq_ring_avail_dx(ring) > AQ_CFG_RESTART_DESC_THRES)
  		aq_ring_queue_wake(ring);
  }
  
  void aq_ring_queue_wake(struct aq_ring_s *ring)
  {
  	struct net_device *ndev = aq_nic_get_ndev(ring->aq_nic);
  
  	if (__netif_subqueue_stopped(ndev, ring->idx)) {
  		netif_wake_subqueue(ndev, ring->idx);
  		ring->stats.tx.queue_restarts++;
  	}
  }
  
  void aq_ring_queue_stop(struct aq_ring_s *ring)
  {
  	struct net_device *ndev = aq_nic_get_ndev(ring->aq_nic);
  
  	if (!__netif_subqueue_stopped(ndev, ring->idx))
  		netif_stop_subqueue(ndev, ring->idx);
  }
  
  bool aq_ring_tx_clean(struct aq_ring_s *self)
  {
  	struct device *dev = aq_nic_get_dev(self->aq_nic);
  	unsigned int budget = AQ_CFG_TX_CLEAN_BUDGET;
  
  	for (; self->sw_head != self->hw_head && budget--;
  		self->sw_head = aq_ring_next_dx(self, self->sw_head)) {
  		struct aq_ring_buff_s *buff = &self->buff_ring[self->sw_head];
  
  		if (likely(buff->is_mapped)) {
  			if (unlikely(buff->is_sop)) {
  				if (!buff->is_eop &&
  				    buff->eop_index != 0xffffU &&
  				    (!aq_ring_dx_in_range(self->sw_head,
  						buff->eop_index,
  						self->hw_head)))
  					break;
  
  				dma_unmap_single(dev, buff->pa, buff->len,
  						 DMA_TO_DEVICE);
  			} else {
  				dma_unmap_page(dev, buff->pa, buff->len,
  					       DMA_TO_DEVICE);
  			}
  		}
  
  		if (unlikely(buff->is_eop))
  			dev_kfree_skb_any(buff->skb);
  
  		buff->pa = 0U;
  		buff->eop_index = 0xffffU;
  	}
  
  	return !!budget;
  }
  
  #define AQ_SKB_ALIGN SKB_DATA_ALIGN(sizeof(struct skb_shared_info))
  int aq_ring_rx_clean(struct aq_ring_s *self,
  		     struct napi_struct *napi,
  		     int *work_done,
  		     int budget)
  {
  	struct net_device *ndev = aq_nic_get_ndev(self->aq_nic);
  	int err = 0;
  	bool is_rsc_completed = true;
  
  	for (; (self->sw_head != self->hw_head) && budget;
  		self->sw_head = aq_ring_next_dx(self, self->sw_head),
  		--budget, ++(*work_done)) {
  		struct aq_ring_buff_s *buff = &self->buff_ring[self->sw_head];
  		struct sk_buff *skb = NULL;
  		unsigned int next_ = 0U;
  		unsigned int i = 0U;
  		struct aq_ring_buff_s *buff_ = NULL;
  
  		if (buff->is_error) {
  			__free_pages(buff->page, 0);
  			continue;
  		}
  
  		if (buff->is_cleaned)
  			continue;
  
  		if (!buff->is_eop) {
  			for (next_ = buff->next,
  			     buff_ = &self->buff_ring[next_]; true;
  			     next_ = buff_->next,
  			     buff_ = &self->buff_ring[next_]) {
  				is_rsc_completed =
  					aq_ring_dx_in_range(self->sw_head,
  							    next_,
  							    self->hw_head);
  
  				if (unlikely(!is_rsc_completed)) {
  					is_rsc_completed = false;
  					break;
  				}
  
  				if (buff_->is_eop)
  					break;
  			}
  
  			if (!is_rsc_completed) {
  				err = 0;
  				goto err_exit;
  			}
  		}
  
  		/* for single fragment packets use build_skb() */
  		if (buff->is_eop &&
  		    buff->len <= AQ_CFG_RX_FRAME_MAX - AQ_SKB_ALIGN) {
  			skb = build_skb(page_address(buff->page),
  					AQ_CFG_RX_FRAME_MAX);
  			if (unlikely(!skb)) {
  				err = -ENOMEM;
  				goto err_exit;
  			}
  
  			skb_put(skb, buff->len);
  		} else {
  			skb = netdev_alloc_skb(ndev, ETH_HLEN);
  			if (unlikely(!skb)) {
  				err = -ENOMEM;
  				goto err_exit;
  			}
  			skb_put(skb, ETH_HLEN);
  			memcpy(skb->data, page_address(buff->page), ETH_HLEN);
  
  			skb_add_rx_frag(skb, 0, buff->page, ETH_HLEN,
  					buff->len - ETH_HLEN,
  					SKB_TRUESIZE(buff->len - ETH_HLEN));
  
  			if (!buff->is_eop) {
  				for (i = 1U, next_ = buff->next,
  				     buff_ = &self->buff_ring[next_];
  				     true; next_ = buff_->next,
  				     buff_ = &self->buff_ring[next_], ++i) {
  					skb_add_rx_frag(skb, i,
  							buff_->page, 0,
  							buff_->len,
  							SKB_TRUESIZE(buff->len -
  							ETH_HLEN));
  					buff_->is_cleaned = 1;
  
  					if (buff_->is_eop)
  						break;
  				}
  			}
  		}
  
  		skb->protocol = eth_type_trans(skb, ndev);
  		if (unlikely(buff->is_cso_err)) {
  			++self->stats.rx.errors;
  			skb->ip_summed = CHECKSUM_NONE;
  		} else {
  			if (buff->is_ip_cso) {
  				__skb_incr_checksum_unnecessary(skb);
  				if (buff->is_udp_cso || buff->is_tcp_cso)
  					__skb_incr_checksum_unnecessary(skb);
  			} else {
  				skb->ip_summed = CHECKSUM_NONE;
  			}
  		}
  
  		skb_set_hash(skb, buff->rss_hash,
  			     buff->is_hash_l4 ? PKT_HASH_TYPE_L4 :
  			     PKT_HASH_TYPE_NONE);
  
  		skb_record_rx_queue(skb, self->idx);
  
  		++self->stats.rx.packets;
  		self->stats.rx.bytes += skb->len;
  
  		napi_gro_receive(napi, skb);
  	}
  
  err_exit:
  	return err;
  }
  
  int aq_ring_rx_fill(struct aq_ring_s *self)
  {
  	unsigned int pages_order = fls(AQ_CFG_RX_FRAME_MAX / PAGE_SIZE +
  		(AQ_CFG_RX_FRAME_MAX % PAGE_SIZE ? 1 : 0)) - 1;
  	struct aq_ring_buff_s *buff = NULL;
  	int err = 0;
  	int i = 0;
  
  	for (i = aq_ring_avail_dx(self); i--;
  		self->sw_tail = aq_ring_next_dx(self, self->sw_tail)) {
  		buff = &self->buff_ring[self->sw_tail];
  
  		buff->flags = 0U;
  		buff->len = AQ_CFG_RX_FRAME_MAX;
  
  		buff->page = alloc_pages(GFP_ATOMIC | __GFP_COMP, pages_order);
  		if (!buff->page) {
  			err = -ENOMEM;
  			goto err_exit;
  		}
  
  		buff->pa = dma_map_page(aq_nic_get_dev(self->aq_nic),
  					buff->page, 0,
  					AQ_CFG_RX_FRAME_MAX, DMA_FROM_DEVICE);
  
  		if (dma_mapping_error(aq_nic_get_dev(self->aq_nic), buff->pa)) {
  			err = -ENOMEM;
  			goto err_exit;
  		}
  
  		buff = NULL;
  	}
  
  err_exit:
  	if (err < 0) {
  		if (buff && buff->page)
  			__free_pages(buff->page, 0);
  	}
  
  	return err;
  }
  
  void aq_ring_rx_deinit(struct aq_ring_s *self)
  {
  	if (!self)
  		goto err_exit;
  
  	for (; self->sw_head != self->sw_tail;
  		self->sw_head = aq_ring_next_dx(self, self->sw_head)) {
  		struct aq_ring_buff_s *buff = &self->buff_ring[self->sw_head];
  
  		dma_unmap_page(aq_nic_get_dev(self->aq_nic), buff->pa,
  			       AQ_CFG_RX_FRAME_MAX, DMA_FROM_DEVICE);
  
  		__free_pages(buff->page, 0);
  	}
  
  err_exit:;
  }
  
  void aq_ring_free(struct aq_ring_s *self)
  {
  	if (!self)
  		goto err_exit;
  
  	kfree(self->buff_ring);
  
  	if (self->dx_ring)
  		dma_free_coherent(aq_nic_get_dev(self->aq_nic),
  				  self->size * self->dx_size, self->dx_ring,
  				  self->dx_ring_pa);
  
  err_exit:;
  }
  