iwlwifi: move RX code to iwl-rx.c

This patch moves partialy rx code into iwl-rx.c as part of iwlcore.
The second part of the code can be merged only with moving of tx
code as well.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 371 insertions, 0 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-rx.c b/drivers/net/wireless/iwlwifi/iwl-rx.c
new file mode 100644
index 000000000000..667b592e6ade
--- /dev/null
+++ b/drivers/net/wireless/iwlwifi/iwl-rx.c
@@ -0,0 +1,371 @@
+/******************************************************************************
+ *
+ * Copyright(c) 2003 - 2008 Intel Corporation. All rights reserved.
+ *
+ * Portions of this file are derived from the ipw3945 project, as well
+ * as portions of the ieee80211 subsystem header files.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110, USA
+ *
+ * The full GNU General Public License is included in this distribution in the
+ * file called LICENSE.
+ *
+ * Contact Information:
+ * James P. Ketrenos <ipw2100-admin@linux.intel.com>
+ * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
+ *
+ *****************************************************************************/
+
+#include <net/mac80211.h>
+#include "iwl-eeprom.h"
+#include "iwl-dev.h"
+#include "iwl-core.h"
+#include "iwl-sta.h"
+#include "iwl-io.h"
+#include "iwl-helpers.h"
+/************************** RX-FUNCTIONS ****************************/
+/*
+ * Rx theory of operation
+ *
+ * Driver allocates a circular buffer of Receive Buffer Descriptors (RBDs),
+ * each of which point to Receive Buffers to be filled by the NIC.  These get
+ * used not only for Rx frames, but for any command response or notification
+ * from the NIC.  The driver and NIC manage the Rx buffers by means
+ * of indexes into the circular buffer.
+ *
+ * Rx Queue Indexes
+ * The host/firmware share two index registers for managing the Rx buffers.
+ *
+ * The READ index maps to the first position that the firmware may be writing
+ * to -- the driver can read up to (but not including) this position and get
+ * good data.
+ * The READ index is managed by the firmware once the card is enabled.
+ *
+ * The WRITE index maps to the last position the driver has read from -- the
+ * position preceding WRITE is the last slot the firmware can place a packet.
+ *
+ * The queue is empty (no good data) if WRITE = READ - 1, and is full if
+ * WRITE = READ.
+ *
+ * During initialization, the host sets up the READ queue position to the first
+ * INDEX position, and WRITE to the last (READ - 1 wrapped)
+ *
+ * When the firmware places a packet in a buffer, it will advance the READ index
+ * and fire the RX interrupt.  The driver can then query the READ index and
+ * process as many packets as possible, moving the WRITE index forward as it
+ * resets the Rx queue buffers with new memory.
+ *
+ * The management in the driver is as follows:
+ * + A list of pre-allocated SKBs is stored in iwl->rxq->rx_free.  When
+ *   iwl->rxq->free_count drops to or below RX_LOW_WATERMARK, work is scheduled
+ *   to replenish the iwl->rxq->rx_free.
+ * + In iwl_rx_replenish (scheduled) if 'processed' != 'read' then the
+ *   iwl->rxq is replenished and the READ INDEX is updated (updating the
+ *   'processed' and 'read' driver indexes as well)
+ * + A received packet is processed and handed to the kernel network stack,
+ *   detached from the iwl->rxq.  The driver 'processed' index is updated.
+ * + The Host/Firmware iwl->rxq is replenished at tasklet time from the rx_free
+ *   list. If there are no allocated buffers in iwl->rxq->rx_free, the READ
+ *   INDEX is not incremented and iwl->status(RX_STALLED) is set.  If there
+ *   were enough free buffers and RX_STALLED is set it is cleared.
+ *
+ *
+ * Driver sequence:
+ *
+ * iwl_rx_queue_alloc()   Allocates rx_free
+ * iwl_rx_replenish()     Replenishes rx_free list from rx_used, and calls
+ *                            iwl_rx_queue_restock
+ * iwl_rx_queue_restock() Moves available buffers from rx_free into Rx
+ *                            queue, updates firmware pointers, and updates
+ *                            the WRITE index.  If insufficient rx_free buffers
+ *                            are available, schedules iwl_rx_replenish
+ *
+ * -- enable interrupts --
+ * ISR - iwl_rx()         Detach iwl_rx_mem_buffers from pool up to the
+ *                            READ INDEX, detaching the SKB from the pool.
+ *                            Moves the packet buffer from queue to rx_used.
+ *                            Calls iwl_rx_queue_restock to refill any empty
+ *                            slots.
+ * ...
+ *
+ */
+
+/**
+ * iwl_rx_queue_space - Return number of free slots available in queue.
+ */
+int iwl_rx_queue_space(const struct iwl_rx_queue *q)
+{
+        int s = q->read - q->write;
+        if (s <= 0)
+                s += RX_QUEUE_SIZE;
+        /* keep some buffer to not confuse full and empty queue */
+        s -= 2;
+        if (s < 0)
+                s = 0;
+        return s;
+}
+EXPORT_SYMBOL(iwl_rx_queue_space);
+
+/**
+ * iwl_rx_queue_update_write_ptr - Update the write pointer for the RX queue
+ */
+int iwl_rx_queue_update_write_ptr(struct iwl_priv *priv, struct iwl_rx_queue *q)
+{
+        u32 reg = 0;
+        int ret = 0;
+        unsigned long flags;
+
+        spin_lock_irqsave(&q->lock, flags);
+
+        if (q->need_update == 0)
+                goto exit_unlock;
+
+        /* If power-saving is in use, make sure device is awake */
+        if (test_bit(STATUS_POWER_PMI, &priv->status)) {
+                reg = iwl_read32(priv, CSR_UCODE_DRV_GP1);
+
+                if (reg & CSR_UCODE_DRV_GP1_BIT_MAC_SLEEP) {
+                        iwl_set_bit(priv, CSR_GP_CNTRL,
+                                    CSR_GP_CNTRL_REG_FLAG_MAC_ACCESS_REQ);
+                        goto exit_unlock;
+                }
+
+                ret = iwl_grab_nic_access(priv);
+                if (ret)
+                        goto exit_unlock;
+
+                /* Device expects a multiple of 8 */
+                iwl_write_direct32(priv, FH_RSCSR_CHNL0_WPTR,
+                                     q->write & ~0x7);
+                iwl_release_nic_access(priv);
+
+        /* Else device is assumed to be awake */
+        } else
+                /* Device expects a multiple of 8 */
+                iwl_write32(priv, FH_RSCSR_CHNL0_WPTR, q->write & ~0x7);
+
+
+        q->need_update = 0;
+
+ exit_unlock:
+        spin_unlock_irqrestore(&q->lock, flags);
+        return ret;
+}
+EXPORT_SYMBOL(iwl_rx_queue_update_write_ptr);
+/**
+ * iwl_dma_addr2rbd_ptr - convert a DMA address to a uCode read buffer ptr
+ */
+static inline __le32 iwl_dma_addr2rbd_ptr(struct iwl_priv *priv,
+                                          dma_addr_t dma_addr)
+{
+        return cpu_to_le32((u32)(dma_addr >> 8));
+}
+
+/**
+ * iwl_rx_queue_restock - refill RX queue from pre-allocated pool
+ *
+ * If there are slots in the RX queue that need to be restocked,
+ * and we have free pre-allocated buffers, fill the ranks as much
+ * as we can, pulling from rx_free.
+ *
+ * This moves the 'write' index forward to catch up with 'processed', and
+ * also updates the memory address in the firmware to reference the new
+ * target buffer.
+ */
+int iwl_rx_queue_restock(struct iwl_priv *priv)
+{
+        struct iwl_rx_queue *rxq = &priv->rxq;
+        struct list_head *element;
+        struct iwl_rx_mem_buffer *rxb;
+        unsigned long flags;
+        int write;
+        int ret = 0;
+
+        spin_lock_irqsave(&rxq->lock, flags);
+        write = rxq->write & ~0x7;
+        while ((iwl_rx_queue_space(rxq) > 0) && (rxq->free_count)) {
+                /* Get next free Rx buffer, remove from free list */
+                element = rxq->rx_free.next;
+                rxb = list_entry(element, struct iwl_rx_mem_buffer, list);
+                list_del(element);
+
+                /* Point to Rx buffer via next RBD in circular buffer */
+                rxq->bd[rxq->write] = iwl_dma_addr2rbd_ptr(priv, rxb->dma_addr);
+                rxq->queue[rxq->write] = rxb;
+                rxq->write = (rxq->write + 1) & RX_QUEUE_MASK;
+                rxq->free_count--;
+        }
+        spin_unlock_irqrestore(&rxq->lock, flags);
+        /* If the pre-allocated buffer pool is dropping low, schedule to
+         * refill it */
+        if (rxq->free_count <= RX_LOW_WATERMARK)
+                queue_work(priv->workqueue, &priv->rx_replenish);
+
+
+        /* If we've added more space for the firmware to place data, tell it.
+         * Increment device's write pointer in multiples of 8. */
+        if ((write != (rxq->write & ~0x7))
+            || (abs(rxq->write - rxq->read) > 7)) {
+                spin_lock_irqsave(&rxq->lock, flags);
+                rxq->need_update = 1;
+                spin_unlock_irqrestore(&rxq->lock, flags);
+                ret = iwl_rx_queue_update_write_ptr(priv, rxq);
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL(iwl_rx_queue_restock);
+
+
+/**
+ * iwl_rx_replenish - Move all used packet from rx_used to rx_free
+ *
+ * When moving to rx_free an SKB is allocated for the slot.
+ *
+ * Also restock the Rx queue via iwl_rx_queue_restock.
+ * This is called as a scheduled work item (except for during initialization)
+ */
+void iwl_rx_allocate(struct iwl_priv *priv)
+{
+        struct iwl_rx_queue *rxq = &priv->rxq;
+        struct list_head *element;
+        struct iwl_rx_mem_buffer *rxb;
+        unsigned long flags;
+        spin_lock_irqsave(&rxq->lock, flags);
+        while (!list_empty(&rxq->rx_used)) {
+                element = rxq->rx_used.next;
+                rxb = list_entry(element, struct iwl_rx_mem_buffer, list);
+
+                /* Alloc a new receive buffer */
+                rxb->skb = alloc_skb(priv->hw_params.rx_buf_size,
+                                __GFP_NOWARN | GFP_ATOMIC);
+                if (!rxb->skb) {
+                        if (net_ratelimit())
+                                printk(KERN_CRIT DRV_NAME
+                                       ": Can not allocate SKB buffers\n");
+                        /* We don't reschedule replenish work here -- we will
+                         * call the restock method and if it still needs
+                         * more buffers it will schedule replenish */
+                        break;
+                }
+                priv->alloc_rxb_skb++;
+                list_del(element);
+
+                /* Get physical address of RB/SKB */
+                rxb->dma_addr =
+                    pci_map_single(priv->pci_dev, rxb->skb->data,
+                           priv->hw_params.rx_buf_size, PCI_DMA_FROMDEVICE);
+                list_add_tail(&rxb->list, &rxq->rx_free);
+                rxq->free_count++;
+        }
+        spin_unlock_irqrestore(&rxq->lock, flags);
+}
+EXPORT_SYMBOL(iwl_rx_allocate);
+
+void iwl_rx_replenish(struct iwl_priv *priv)
+{
+        unsigned long flags;
+
+        iwl_rx_allocate(priv);
+
+        spin_lock_irqsave(&priv->lock, flags);
+        iwl_rx_queue_restock(priv);
+        spin_unlock_irqrestore(&priv->lock, flags);
+}
+EXPORT_SYMBOL(iwl_rx_replenish);
+
+
+/* Assumes that the skb field of the buffers in 'pool' is kept accurate.
+ * If an SKB has been detached, the POOL needs to have its SKB set to NULL
+ * This free routine walks the list of POOL entries and if SKB is set to
+ * non NULL it is unmapped and freed
+ */
+void iwl_rx_queue_free(struct iwl_priv *priv, struct iwl_rx_queue *rxq)
+{
+        int i;
+        for (i = 0; i < RX_QUEUE_SIZE + RX_FREE_BUFFERS; i++) {
+                if (rxq->pool[i].skb != NULL) {
+                        pci_unmap_single(priv->pci_dev,
+                                         rxq->pool[i].dma_addr,
+                                         priv->hw_params.rx_buf_size,
+                                         PCI_DMA_FROMDEVICE);
+                        dev_kfree_skb(rxq->pool[i].skb);
+                }
+        }
+
+        pci_free_consistent(priv->pci_dev, 4 * RX_QUEUE_SIZE, rxq->bd,
+                            rxq->dma_addr);
+        rxq->bd = NULL;
+}
+EXPORT_SYMBOL(iwl_rx_queue_free);
+
+int iwl_rx_queue_alloc(struct iwl_priv *priv)
+{
+        struct iwl_rx_queue *rxq = &priv->rxq;
+        struct pci_dev *dev = priv->pci_dev;
+        int i;
+
+        spin_lock_init(&rxq->lock);
+        INIT_LIST_HEAD(&rxq->rx_free);
+        INIT_LIST_HEAD(&rxq->rx_used);
+
+        /* Alloc the circular buffer of Read Buffer Descriptors (RBDs) */
+        rxq->bd = pci_alloc_consistent(dev, 4 * RX_QUEUE_SIZE, &rxq->dma_addr);
+        if (!rxq->bd)
+                return -ENOMEM;
+
+        /* Fill the rx_used queue with _all_ of the Rx buffers */
+        for (i = 0; i < RX_FREE_BUFFERS + RX_QUEUE_SIZE; i++)
+                list_add_tail(&rxq->pool[i].list, &rxq->rx_used);
+
+        /* Set us so that we have processed and used all buffers, but have
+         * not restocked the Rx queue with fresh buffers */
+        rxq->read = rxq->write = 0;
+        rxq->free_count = 0;
+        rxq->need_update = 0;
+        return 0;
+}
+EXPORT_SYMBOL(iwl_rx_queue_alloc);
+
+void iwl_rx_queue_reset(struct iwl_priv *priv, struct iwl_rx_queue *rxq)
+{
+        unsigned long flags;
+        int i;
+        spin_lock_irqsave(&rxq->lock, flags);
+        INIT_LIST_HEAD(&rxq->rx_free);
+        INIT_LIST_HEAD(&rxq->rx_used);
+        /* Fill the rx_used queue with _all_ of the Rx buffers */
+        for (i = 0; i < RX_FREE_BUFFERS + RX_QUEUE_SIZE; i++) {
+                /* In the reset function, these buffers may have been allocated
+                 * to an SKB, so we need to unmap and free potential storage */
+                if (rxq->pool[i].skb != NULL) {
+                        pci_unmap_single(priv->pci_dev,
+                                         rxq->pool[i].dma_addr,
+                                         priv->hw_params.rx_buf_size,
+                                         PCI_DMA_FROMDEVICE);
+                        priv->alloc_rxb_skb--;
+                        dev_kfree_skb(rxq->pool[i].skb);
+                        rxq->pool[i].skb = NULL;
+                }
+                list_add_tail(&rxq->pool[i].list, &rxq->rx_used);
+        }
+
+        /* Set us so that we have processed and used all buffers, but have
+         * not restocked the Rx queue with fresh buffers */
+        rxq->read = rxq->write = 0;
+        rxq->free_count = 0;
+        spin_unlock_irqrestore(&rxq->lock, flags);
+}
+EXPORT_SYMBOL(iwl_rx_queue_reset);
+