2 files changed, 447 insertions, 21 deletions

diff --git a/drivers/net/ks8842.c b/drivers/net/ks8842.c
index 289b0bee3462..3fe38c787f29 100644
--- a/drivers/net/ks8842.c
+++ b/drivers/net/ks8842.c
@@ -30,6 +30,9 @@
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/ks8842.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
 
 #define DRV_NAME "ks8842"
 
@@ -82,6 +85,15 @@
 #define IRQ_RX_ERROR    0x0080
 #define ENABLED_IRQS    (IRQ_LINK_CHANGE | IRQ_TX | IRQ_RX | IRQ_RX_STOPPED | \
                 IRQ_TX_STOPPED | IRQ_RX_OVERRUN | IRQ_RX_ERROR)
+/* When running via timberdale in DMA mode, the RX interrupt should be
+   enabled in the KS8842, but not in the FPGA IP, since the IP handles
+   RX DMA internally.
+   TX interrupts are not needed it is handled by the FPGA the driver is
+   notified via DMA callbacks.
+*/
+#define ENABLED_IRQS_DMA_IP     (IRQ_LINK_CHANGE | IRQ_RX_STOPPED | \
+        IRQ_TX_STOPPED | IRQ_RX_OVERRUN | IRQ_RX_ERROR)
+#define ENABLED_IRQS_DMA        (ENABLED_IRQS_DMA_IP | IRQ_RX)
 #define REG_ISR         0x02
 #define REG_RXSR        0x04
 #define RXSR_VALID      0x8000
@@ -124,6 +136,28 @@
 #define MICREL_KS884X           0x01    /* 0=Timeberdale(FPGA), 1=Micrel */
 #define KS884X_16BIT            0x02    /*  1=16bit, 0=32bit */
 
+#define DMA_BUFFER_SIZE         2048
+
+struct ks8842_tx_dma_ctl {
+        struct dma_chan *chan;
+        struct dma_async_tx_descriptor *adesc;
+        void *buf;
+        struct scatterlist sg;
+        int channel;
+};
+
+struct ks8842_rx_dma_ctl {
+        struct dma_chan *chan;
+        struct dma_async_tx_descriptor *adesc;
+        struct sk_buff  *skb;
+        struct scatterlist sg;
+        struct tasklet_struct tasklet;
+        int channel;
+};
+
+#define KS8842_USE_DMA(adapter) (((adapter)->dma_tx.channel != -1) && \
+         ((adapter)->dma_rx.channel != -1))
+
 struct ks8842_adapter {
         void __iomem    *hw_addr;
         int             irq;
@@ -132,8 +166,19 @@ struct ks8842_adapter {
         spinlock_t      lock; /* spinlock to be interrupt safe */
         struct work_struct timeout_work;
         struct net_device *netdev;
+        struct device *dev;
+        struct ks8842_tx_dma_ctl        dma_tx;
+        struct ks8842_rx_dma_ctl        dma_rx;
 };
 
+static void ks8842_dma_rx_cb(void *data);
+static void ks8842_dma_tx_cb(void *data);
+
+static inline void ks8842_resume_dma(struct ks8842_adapter *adapter)
+{
+        iowrite32(1, adapter->hw_addr + REQ_TIMB_DMA_RESUME);
+}
+
 static inline void ks8842_select_bank(struct ks8842_adapter *adapter, u16 bank)
 {
         iowrite16(bank, adapter->hw_addr + REG_SELECT_BANK);
@@ -297,8 +342,19 @@ static void ks8842_reset_hw(struct ks8842_adapter *adapter)
         ks8842_write16(adapter, 18, 0xffff, REG_ISR);
 
         /* enable interrupts */
-        ks8842_write16(adapter, 18, ENABLED_IRQS, REG_IER);
-
+        if (KS8842_USE_DMA(adapter)) {
+                /* When running in DMA Mode the RX interrupt is not enabled in
+                   timberdale because RX data is received by DMA callbacks
+                   it must still be enabled in the KS8842 because it indicates
+                   to timberdale when there is RX data for it's DMA FIFOs */
+                iowrite16(ENABLED_IRQS_DMA_IP, adapter->hw_addr + REG_TIMB_IER);
+                ks8842_write16(adapter, 18, ENABLED_IRQS_DMA, REG_IER);
+        } else {
+                if (!(adapter->conf_flags & MICREL_KS884X))
+                        iowrite16(ENABLED_IRQS,
+                                adapter->hw_addr + REG_TIMB_IER);
+                ks8842_write16(adapter, 18, ENABLED_IRQS, REG_IER);
+        }
         /* enable the switch */
         ks8842_write16(adapter, 32, 0x1, REG_SW_ID_AND_ENABLE);
 }
@@ -371,6 +427,53 @@ static inline u16 ks8842_tx_fifo_space(struct ks8842_adapter *adapter)
         return ks8842_read16(adapter, 16, REG_TXMIR) & 0x1fff;
 }
 
+static int ks8842_tx_frame_dma(struct sk_buff *skb, struct net_device *netdev)
+{
+        struct ks8842_adapter *adapter = netdev_priv(netdev);
+        struct ks8842_tx_dma_ctl *ctl = &adapter->dma_tx;
+        u8 *buf = ctl->buf;
+
+        if (ctl->adesc) {
+                netdev_dbg(netdev, "%s: TX ongoing\n", __func__);
+                /* transfer ongoing */
+                return NETDEV_TX_BUSY;
+        }
+
+        sg_dma_len(&ctl->sg) = skb->len + sizeof(u32);
+
+        /* copy data to the TX buffer */
+        /* the control word, enable IRQ, port 1 and the length */
+        *buf++ = 0x00;
+        *buf++ = 0x01; /* Port 1 */
+        *buf++ = skb->len & 0xff;
+        *buf++ = (skb->len >> 8) & 0xff;
+        skb_copy_from_linear_data(skb, buf, skb->len);
+
+        dma_sync_single_range_for_device(adapter->dev,
+                sg_dma_address(&ctl->sg), 0, sg_dma_len(&ctl->sg),
+                DMA_TO_DEVICE);
+
+        /* make sure the length is a multiple of 4 */
+        if (sg_dma_len(&ctl->sg) % 4)
+                sg_dma_len(&ctl->sg) += 4 - sg_dma_len(&ctl->sg) % 4;
+
+        ctl->adesc = ctl->chan->device->device_prep_slave_sg(ctl->chan,
+                &ctl->sg, 1, DMA_TO_DEVICE,
+                DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_SRC_UNMAP);
+        if (!ctl->adesc)
+                return NETDEV_TX_BUSY;
+
+        ctl->adesc->callback_param = netdev;
+        ctl->adesc->callback = ks8842_dma_tx_cb;
+        ctl->adesc->tx_submit(ctl->adesc);
+
+        netdev->stats.tx_bytes += skb->len;
+
+        dev_kfree_skb(skb);
+
+        return NETDEV_TX_OK;
+}
+
 static int ks8842_tx_frame(struct sk_buff *skb, struct net_device *netdev)
 {
         struct ks8842_adapter *adapter = netdev_priv(netdev);
@@ -422,6 +525,121 @@ static int ks8842_tx_frame(struct sk_buff *skb, struct net_device *netdev)
         return NETDEV_TX_OK;
 }
 
+static void ks8842_update_rx_err_counters(struct net_device *netdev, u32 status)
+{
+        netdev_dbg(netdev, "RX error, status: %x\n", status);
+
+        netdev->stats.rx_errors++;
+        if (status & RXSR_TOO_LONG)
+                netdev->stats.rx_length_errors++;
+        if (status & RXSR_CRC_ERROR)
+                netdev->stats.rx_crc_errors++;
+        if (status & RXSR_RUNT)
+                netdev->stats.rx_frame_errors++;
+}
+
+static void ks8842_update_rx_counters(struct net_device *netdev, u32 status,
+        int len)
+{
+        netdev_dbg(netdev, "RX packet, len: %d\n", len);
+
+        netdev->stats.rx_packets++;
+        netdev->stats.rx_bytes += len;
+        if (status & RXSR_MULTICAST)
+                netdev->stats.multicast++;
+}
+
+static int __ks8842_start_new_rx_dma(struct net_device *netdev)
+{
+        struct ks8842_adapter *adapter = netdev_priv(netdev);
+        struct ks8842_rx_dma_ctl *ctl = &adapter->dma_rx;
+        struct scatterlist *sg = &ctl->sg;
+        int err;
+
+        ctl->skb = netdev_alloc_skb(netdev, DMA_BUFFER_SIZE);
+        if (ctl->skb) {
+                sg_init_table(sg, 1);
+                sg_dma_address(sg) = dma_map_single(adapter->dev,
+                        ctl->skb->data, DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
+                err = dma_mapping_error(adapter->dev, sg_dma_address(sg));
+                if (unlikely(err)) {
+                        sg_dma_address(sg) = 0;
+                        goto out;
+                }
+
+                sg_dma_len(sg) = DMA_BUFFER_SIZE;
+
+                ctl->adesc = ctl->chan->device->device_prep_slave_sg(ctl->chan,
+                        sg, 1, DMA_FROM_DEVICE,
+                        DMA_PREP_INTERRUPT | DMA_COMPL_SKIP_SRC_UNMAP);
+
+                if (!ctl->adesc)
+                        goto out;
+
+                ctl->adesc->callback_param = netdev;
+                ctl->adesc->callback = ks8842_dma_rx_cb;
+                ctl->adesc->tx_submit(ctl->adesc);
+        } else {
+                err = -ENOMEM;
+                sg_dma_address(sg) = 0;
+                goto out;
+        }
+
+        return err;
+out:
+        if (sg_dma_address(sg))
+                dma_unmap_single(adapter->dev, sg_dma_address(sg),
+                        DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
+        sg_dma_address(sg) = 0;
+        if (ctl->skb)
+                dev_kfree_skb(ctl->skb);
+
+        ctl->skb = NULL;
+
+        printk(KERN_ERR DRV_NAME": Failed to start RX DMA: %d\n", err);
+        return err;
+}
+
+static void ks8842_rx_frame_dma_tasklet(unsigned long arg)
+{
+        struct net_device *netdev = (struct net_device *)arg;
+        struct ks8842_adapter *adapter = netdev_priv(netdev);
+        struct ks8842_rx_dma_ctl *ctl = &adapter->dma_rx;
+        struct sk_buff *skb = ctl->skb;
+        dma_addr_t addr = sg_dma_address(&ctl->sg);
+        u32 status;
+
+        ctl->adesc = NULL;
+
+        /* kick next transfer going */
+        __ks8842_start_new_rx_dma(netdev);
+
+        /* now handle the data we got */
+        dma_unmap_single(adapter->dev, addr, DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
+
+        status = *((u32 *)skb->data);
+
+        netdev_dbg(netdev, "%s - rx_data: status: %x\n",
+                __func__, status & 0xffff);
+
+        /* check the status */
+        if ((status & RXSR_VALID) && !(status & RXSR_ERROR)) {
+                int len = (status >> 16) & 0x7ff;
+
+                ks8842_update_rx_counters(netdev, status, len);
+
+                /* reserve 4 bytes which is the status word */
+                skb_reserve(skb, 4);
+                skb_put(skb, len);
+
+                skb->protocol = eth_type_trans(skb, netdev);
+                netif_rx(skb);
+        } else {
+                ks8842_update_rx_err_counters(netdev, status);
+                dev_kfree_skb(skb);
+        }
+}
+
 static void ks8842_rx_frame(struct net_device *netdev,
         struct ks8842_adapter *adapter)
 {
@@ -445,13 +663,9 @@ static void ks8842_rx_frame(struct net_device *netdev,
         if ((status & RXSR_VALID) && !(status & RXSR_ERROR)) {
                 struct sk_buff *skb = netdev_alloc_skb_ip_align(netdev, len);
 
-                netdev_dbg(netdev, "%s, got package, len: %d\n", __func__, len);
                 if (skb) {
 
-                        netdev->stats.rx_packets++;
-                        netdev->stats.rx_bytes += len;
-                        if (status & RXSR_MULTICAST)
-                                netdev->stats.multicast++;
+                        ks8842_update_rx_counters(netdev, status, len);
 
                         if (adapter->conf_flags & KS884X_16BIT) {
                                 u16 *data16 = (u16 *)skb_put(skb, len);
@@ -477,16 +691,8 @@ static void ks8842_rx_frame(struct net_device *netdev,
                         netif_rx(skb);
                 } else
                         netdev->stats.rx_dropped++;
-        } else {
-                netdev_dbg(netdev, "RX error, status: %x\n", status);
-                netdev->stats.rx_errors++;
-                if (status & RXSR_TOO_LONG)
-                        netdev->stats.rx_length_errors++;
-                if (status & RXSR_CRC_ERROR)
-                        netdev->stats.rx_crc_errors++;
-                if (status & RXSR_RUNT)
-                        netdev->stats.rx_frame_errors++;
-        }
+        } else
+                ks8842_update_rx_err_counters(netdev, status);
 
         /* set high watermark to 3K */
         ks8842_clear_bits(adapter, 0, 1 << 12, REG_QRFCR);
@@ -541,6 +747,12 @@ void ks8842_tasklet(unsigned long arg)
         isr = ks8842_read16(adapter, 18, REG_ISR);
         netdev_dbg(netdev, "%s - ISR: 0x%x\n", __func__, isr);
 
+        /* when running in DMA mode, do not ack RX interrupts, it is handled
+           internally by timberdale, otherwise it's DMA FIFO:s would stop
+        */
+        if (KS8842_USE_DMA(adapter))
+                isr &= ~IRQ_RX;
+
         /* Ack */
         ks8842_write16(adapter, 18, isr, REG_ISR);
 
@@ -554,9 +766,11 @@ void ks8842_tasklet(unsigned long arg)
         if (isr & IRQ_LINK_CHANGE)
                 ks8842_update_link_status(netdev, adapter);
 
-        if (isr & (IRQ_RX | IRQ_RX_ERROR))
+        /* should not get IRQ_RX when running DMA mode */
+        if (isr & (IRQ_RX | IRQ_RX_ERROR) && !KS8842_USE_DMA(adapter))
                 ks8842_handle_rx(netdev, adapter);
 
+        /* should only happen when in PIO mode */
         if (isr & IRQ_TX)
                 ks8842_handle_tx(netdev, adapter);
 
@@ -575,8 +789,17 @@ void ks8842_tasklet(unsigned long arg)
 
         /* re-enable interrupts, put back the bank selection register */
         spin_lock_irqsave(&adapter->lock, flags);
-        ks8842_write16(adapter, 18, ENABLED_IRQS, REG_IER);
+        if (KS8842_USE_DMA(adapter))
+                ks8842_write16(adapter, 18, ENABLED_IRQS_DMA, REG_IER);
+        else
+                ks8842_write16(adapter, 18, ENABLED_IRQS, REG_IER);
         iowrite16(entry_bank, adapter->hw_addr + REG_SELECT_BANK);
+
+        /* Make sure timberdale continues DMA operations, they are stopped while
+           we are handling the ks8842 because we might change bank */
+        if (KS8842_USE_DMA(adapter))
+                ks8842_resume_dma(adapter);
+
         spin_unlock_irqrestore(&adapter->lock, flags);
 }
 
@@ -592,8 +815,12 @@ static irqreturn_t ks8842_irq(int irq, void *devid)
         netdev_dbg(netdev, "%s - ISR: 0x%x\n", __func__, isr);
 
         if (isr) {
-                /* disable IRQ */
-                ks8842_write16(adapter, 18, 0x00, REG_IER);
+                if (KS8842_USE_DMA(adapter))
+                        /* disable all but RX IRQ, since the FPGA relies on it*/
+                        ks8842_write16(adapter, 18, IRQ_RX, REG_IER);
+                else
+                        /* disable IRQ */
+                        ks8842_write16(adapter, 18, 0x00, REG_IER);
 
                 /* schedule tasklet */
                 tasklet_schedule(&adapter->tasklet);
@@ -603,9 +830,151 @@ static irqreturn_t ks8842_irq(int irq, void *devid)
 
         iowrite16(entry_bank, adapter->hw_addr + REG_SELECT_BANK);
 
+        /* After an interrupt, tell timberdale to continue DMA operations.
+           DMA is disabled while we are handling the ks8842 because we might
+           change bank */
+        ks8842_resume_dma(adapter);
+
         return ret;
 }
 
+static void ks8842_dma_rx_cb(void *data)
+{
+        struct net_device       *netdev = data;
+        struct ks8842_adapter   *adapter = netdev_priv(netdev);
+
+        netdev_dbg(netdev, "RX DMA finished\n");
+        /* schedule tasklet */
+        if (adapter->dma_rx.adesc)
+                tasklet_schedule(&adapter->dma_rx.tasklet);
+}
+
+static void ks8842_dma_tx_cb(void *data)
+{
+        struct net_device               *netdev = data;
+        struct ks8842_adapter           *adapter = netdev_priv(netdev);
+        struct ks8842_tx_dma_ctl        *ctl = &adapter->dma_tx;
+
+        netdev_dbg(netdev, "TX DMA finished\n");
+
+        if (!ctl->adesc)
+                return;
+
+        netdev->stats.tx_packets++;
+        ctl->adesc = NULL;
+
+        if (netif_queue_stopped(netdev))
+                netif_wake_queue(netdev);
+}
+
+static void ks8842_stop_dma(struct ks8842_adapter *adapter)
+{
+        struct ks8842_tx_dma_ctl *tx_ctl = &adapter->dma_tx;
+        struct ks8842_rx_dma_ctl *rx_ctl = &adapter->dma_rx;
+
+        tx_ctl->adesc = NULL;
+        if (tx_ctl->chan)
+                tx_ctl->chan->device->device_control(tx_ctl->chan,
+                        DMA_TERMINATE_ALL, 0);
+
+        rx_ctl->adesc = NULL;
+        if (rx_ctl->chan)
+                rx_ctl->chan->device->device_control(rx_ctl->chan,
+                        DMA_TERMINATE_ALL, 0);
+
+        if (sg_dma_address(&rx_ctl->sg))
+                dma_unmap_single(adapter->dev, sg_dma_address(&rx_ctl->sg),
+                        DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
+        sg_dma_address(&rx_ctl->sg) = 0;
+
+        dev_kfree_skb(rx_ctl->skb);
+        rx_ctl->skb = NULL;
+}
+
+static void ks8842_dealloc_dma_bufs(struct ks8842_adapter *adapter)
+{
+        struct ks8842_tx_dma_ctl *tx_ctl = &adapter->dma_tx;
+        struct ks8842_rx_dma_ctl *rx_ctl = &adapter->dma_rx;
+
+        ks8842_stop_dma(adapter);
+
+        if (tx_ctl->chan)
+                dma_release_channel(tx_ctl->chan);
+        tx_ctl->chan = NULL;
+
+        if (rx_ctl->chan)
+                dma_release_channel(rx_ctl->chan);
+        rx_ctl->chan = NULL;
+
+        tasklet_kill(&rx_ctl->tasklet);
+
+        if (sg_dma_address(&tx_ctl->sg))
+                dma_unmap_single(adapter->dev, sg_dma_address(&tx_ctl->sg),
+                        DMA_BUFFER_SIZE, DMA_TO_DEVICE);
+        sg_dma_address(&tx_ctl->sg) = 0;
+
+        kfree(tx_ctl->buf);
+        tx_ctl->buf = NULL;
+}
+
+static bool ks8842_dma_filter_fn(struct dma_chan *chan, void *filter_param)
+{
+        return chan->chan_id == (int)filter_param;
+}
+
+static int ks8842_alloc_dma_bufs(struct net_device *netdev)
+{
+        struct ks8842_adapter *adapter = netdev_priv(netdev);
+        struct ks8842_tx_dma_ctl *tx_ctl = &adapter->dma_tx;
+        struct ks8842_rx_dma_ctl *rx_ctl = &adapter->dma_rx;
+        int err;
+
+        dma_cap_mask_t mask;
+
+        dma_cap_zero(mask);
+        dma_cap_set(DMA_SLAVE, mask);
+        dma_cap_set(DMA_PRIVATE, mask);
+
+        sg_init_table(&tx_ctl->sg, 1);
+
+        tx_ctl->chan = dma_request_channel(mask, ks8842_dma_filter_fn,
+                (void *)tx_ctl->channel);
+        if (!tx_ctl->chan) {
+                err = -ENODEV;
+                goto err;
+        }
+
+        /* allocate DMA buffer */
+        tx_ctl->buf = kmalloc(DMA_BUFFER_SIZE, GFP_KERNEL);
+        if (!tx_ctl->buf) {
+                err = -ENOMEM;
+                goto err;
+        }
+
+        sg_dma_address(&tx_ctl->sg) = dma_map_single(adapter->dev,
+                tx_ctl->buf, DMA_BUFFER_SIZE, DMA_TO_DEVICE);
+        err = dma_mapping_error(adapter->dev,
+                sg_dma_address(&tx_ctl->sg));
+        if (err) {
+                sg_dma_address(&tx_ctl->sg) = 0;
+                goto err;
+        }
+
+        rx_ctl->chan = dma_request_channel(mask, ks8842_dma_filter_fn,
+                (void *)rx_ctl->channel);
+        if (!rx_ctl->chan) {
+                err = -ENODEV;
+                goto err;
+        }
+
+        tasklet_init(&rx_ctl->tasklet, ks8842_rx_frame_dma_tasklet,
+                (unsigned long)netdev);
+
+        return 0;
+err:
+        ks8842_dealloc_dma_bufs(adapter);
+        return err;
+}
 
 /* Netdevice operations */
 
@@ -616,6 +985,25 @@ static int ks8842_open(struct net_device *netdev)
 
         netdev_dbg(netdev, "%s - entry\n", __func__);
 
+        if (KS8842_USE_DMA(adapter)) {
+                err = ks8842_alloc_dma_bufs(netdev);
+
+                if (!err) {
+                        /* start RX dma */
+                        err = __ks8842_start_new_rx_dma(netdev);
+                        if (err)
+                                ks8842_dealloc_dma_bufs(adapter);
+                }
+
+                if (err) {
+                        printk(KERN_WARNING DRV_NAME
+                                ": Failed to initiate DMA, running PIO\n");
+                        ks8842_dealloc_dma_bufs(adapter);
+                        adapter->dma_rx.channel = -1;
+                        adapter->dma_tx.channel = -1;
+                }
+        }
+
         /* reset the HW */
         ks8842_reset_hw(adapter);
 
@@ -641,6 +1029,9 @@ static int ks8842_close(struct net_device *netdev)
 
         cancel_work_sync(&adapter->timeout_work);
 
+        if (KS8842_USE_DMA(adapter))
+                ks8842_dealloc_dma_bufs(adapter);
+
         /* free the irq */
         free_irq(adapter->irq, netdev);
 
@@ -658,6 +1049,17 @@ static netdev_tx_t ks8842_xmit_frame(struct sk_buff *skb,
 
         netdev_dbg(netdev, "%s: entry\n", __func__);
 
+        if (KS8842_USE_DMA(adapter)) {
+                unsigned long flags;
+                ret = ks8842_tx_frame_dma(skb, netdev);
+                /* for now only allow one transfer at the time */
+                spin_lock_irqsave(&adapter->lock, flags);
+                if (adapter->dma_tx.adesc)
+                        netif_stop_queue(netdev);
+                spin_unlock_irqrestore(&adapter->lock, flags);
+                return ret;
+        }
+
         ret = ks8842_tx_frame(skb, netdev);
 
         if (ks8842_tx_fifo_space(adapter) <  netdev->mtu + 8)
@@ -693,6 +1095,10 @@ static void ks8842_tx_timeout_work(struct work_struct *work)
         netdev_dbg(netdev, "%s: entry\n", __func__);
 
         spin_lock_irqsave(&adapter->lock, flags);
+
+        if (KS8842_USE_DMA(adapter))
+                ks8842_stop_dma(adapter);
+
         /* disable interrupts */
         ks8842_write16(adapter, 18, 0, REG_IER);
         ks8842_write16(adapter, 18, 0xFFFF, REG_ISR);
@@ -706,6 +1112,9 @@ static void ks8842_tx_timeout_work(struct work_struct *work)
         ks8842_write_mac_addr(adapter, netdev->dev_addr);
 
         ks8842_update_link_status(netdev, adapter);
+
+        if (KS8842_USE_DMA(adapter))
+                __ks8842_start_new_rx_dma(netdev);
 }
 
 static void ks8842_tx_timeout(struct net_device *netdev)
@@ -765,6 +1174,19 @@ static int __devinit ks8842_probe(struct platform_device *pdev)
                 goto err_get_irq;
         }
 
+        adapter->dev = (pdev->dev.parent) ? pdev->dev.parent : &pdev->dev;
+
+        /* DMA is only supported when accessed via timberdale */
+        if (!(adapter->conf_flags & MICREL_KS884X) && pdata &&
+                (pdata->tx_dma_channel != -1) &&
+                (pdata->rx_dma_channel != -1)) {
+                adapter->dma_rx.channel = pdata->rx_dma_channel;
+                adapter->dma_tx.channel = pdata->tx_dma_channel;
+        } else {
+                adapter->dma_rx.channel = -1;
+                adapter->dma_tx.channel = -1;
+        }
+
         tasklet_init(&adapter->tasklet, ks8842_tasklet, (unsigned long)netdev);
         spin_lock_init(&adapter->lock);
 
diff --git a/include/linux/ks8842.h b/include/linux/ks8842.h
index da0341b8ca0a..14ba4452296e 100644
--- a/include/linux/ks8842.h
+++ b/include/linux/ks8842.h
@@ -25,10 +25,14 @@
  * struct ks8842_platform_data - Platform data of the KS8842 network driver
  * @macaddr:    The MAC address of the device, set to all 0:s to use the on in
  *              the chip.
+ * @rx_dma_channel:     The DMA channel to use for RX, -1 for none.
+ * @tx_dma_channel:     The DMA channel to use for TX, -1 for none.
  *
  */
 struct ks8842_platform_data {
         u8 macaddr[ETH_ALEN];
+        int rx_dma_channel;
+        int tx_dma_channel;
 };
 
 #endif