NET: sa11x0-ir: add DMA support for SIR transmit mode
As the DMA engine API allows DMA channels to be reconfigured on the
fly, we can now support switching the DMA channel configuration to
support SIR transmit DMA without needing to claim an additional
physical DMA channel - thereby using up half the DMA channels just
for one driver.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/net/irda/sa1100_ir.c b/drivers/net/irda/sa1100_ir.c
index 620a48d..a0d1913 100644
--- a/drivers/net/irda/sa1100_ir.c
+++ b/drivers/net/irda/sa1100_ir.c
@@ -81,6 +81,13 @@
#define HPSIR_MAX_RXLEN 2047
+static struct dma_slave_config sa1100_irda_sir_tx = {
+ .direction = DMA_TO_DEVICE,
+ .dst_addr = __PREG(Ser2UTDR),
+ .dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+ .dst_maxburst = 4,
+};
+
static struct dma_slave_config sa1100_irda_fir_rx = {
.direction = DMA_FROM_DEVICE,
.src_addr = __PREG(Ser2HSDR),
@@ -215,6 +222,36 @@
/*
* HP-SIR format support.
*/
+static void sa1100_irda_sirtxdma_irq(void *id)
+{
+ struct net_device *dev = id;
+ struct sa1100_irda *si = netdev_priv(dev);
+
+ dma_unmap_sg(si->dma_tx.dev, &si->dma_tx.sg, 1, DMA_TO_DEVICE);
+ dev_kfree_skb(si->dma_tx.skb);
+ si->dma_tx.skb = NULL;
+
+ dev->stats.tx_packets++;
+ dev->stats.tx_bytes += sg_dma_len(&si->dma_tx.sg);
+
+ /* We need to ensure that the transmitter has finished. */
+ do
+ rmb();
+ while (Ser2UTSR1 & UTSR1_TBY);
+
+ /*
+ * Ok, we've finished transmitting. Now enable the receiver.
+ * Sometimes we get a receive IRQ immediately after a transmit...
+ */
+ Ser2UTSR0 = UTSR0_REB | UTSR0_RBB | UTSR0_RID;
+ Ser2UTCR3 = UTCR3_RIE | UTCR3_RXE | UTCR3_TXE;
+
+ sa1100_irda_check_speed(si);
+
+ /* I'm hungry! */
+ netif_wake_queue(dev);
+}
+
static int sa1100_irda_sir_tx_start(struct sk_buff *skb, struct net_device *dev,
struct sa1100_irda *si)
{
@@ -222,14 +259,22 @@
si->tx_buff.len = async_wrap_skb(skb, si->tx_buff.data,
si->tx_buff.truesize);
- /*
- * Set the transmit interrupt enable. This will fire off an
- * interrupt immediately. Note that we disable the receiver
- * so we won't get spurious characters received.
- */
- Ser2UTCR3 = UTCR3_TIE | UTCR3_TXE;
+ si->dma_tx.skb = skb;
+ sg_set_buf(&si->dma_tx.sg, si->tx_buff.data, si->tx_buff.len);
+ if (dma_map_sg(si->dma_tx.dev, &si->dma_tx.sg, 1, DMA_TO_DEVICE) == 0) {
+ si->dma_tx.skb = NULL;
+ netif_wake_queue(dev);
+ dev->stats.tx_dropped++;
+ return NETDEV_TX_OK;
+ }
- dev_kfree_skb(skb);
+ sa1100_irda_dma_start(&si->dma_tx, DMA_MEM_TO_DEV, sa1100_irda_sirtxdma_irq, dev);
+
+ /*
+ * The mean turn-around time is enforced by XBOF padding,
+ * so we don't have to do anything special here.
+ */
+ Ser2UTCR3 = UTCR3_TXE;
return NETDEV_TX_OK;
}
@@ -288,43 +333,6 @@
}
- if (status & UTSR0_TFS && si->tx_buff.len) {
- /*
- * Transmitter FIFO is not full
- */
- do {
- Ser2UTDR = *si->tx_buff.data++;
- si->tx_buff.len -= 1;
- } while (Ser2UTSR1 & UTSR1_TNF && si->tx_buff.len);
-
- if (si->tx_buff.len == 0) {
- dev->stats.tx_packets++;
- dev->stats.tx_bytes += si->tx_buff.data -
- si->tx_buff.head;
-
- /*
- * We need to ensure that the transmitter has
- * finished.
- */
- do
- rmb();
- while (Ser2UTSR1 & UTSR1_TBY);
-
- /*
- * Ok, we've finished transmitting. Now enable
- * the receiver. Sometimes we get a receive IRQ
- * immediately after a transmit...
- */
- Ser2UTSR0 = UTSR0_REB | UTSR0_RBB | UTSR0_RID;
- Ser2UTCR3 = UTCR3_RIE | UTCR3_RXE | UTCR3_TXE;
-
- sa1100_irda_check_speed(si);
-
- /* I'm hungry! */
- netif_wake_queue(dev);
- }
- }
-
return IRQ_HANDLED;
}
@@ -545,8 +553,11 @@
brd = 3686400 / (16 * speed) - 1;
/* Stop the receive DMA, and configure transmit. */
- if (IS_FIR(si))
+ if (IS_FIR(si)) {
dmaengine_terminate_all(si->dma_rx.chan);
+ dmaengine_slave_config(si->dma_tx.chan,
+ &sa1100_irda_sir_tx);
+ }
local_irq_save(flags);
@@ -574,6 +585,10 @@
break;
case 4000000:
+ if (!IS_FIR(si))
+ dmaengine_slave_config(si->dma_tx.chan,
+ &sa1100_irda_fir_tx);
+
local_irq_save(flags);
Ser2HSSR0 = 0xff;