pch_uart: add multi-scatter processing

Currently, this driver can handle only single scatterlist.
Thus, it can't send data beyond FIFO size.

This patch enables this driver can handle multiple scatter list.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 3b2fb93..c1386eb 100644 (file)
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -226,7 +226,8 @@ struct eg20t_port {
        struct pch_dma_slave            param_rx;
        struct dma_chan                 *chan_tx;
        struct dma_chan                 *chan_rx;
-       struct scatterlist              sg_tx;
+       struct scatterlist              *sg_tx_p;
+       int                             nent;
        struct scatterlist              sg_rx;
        int                             tx_dma_use;
        void                            *rx_buf_virt;
@@ -595,16 +596,20 @@ static void pch_dma_rx_complete(void *arg)
        struct eg20t_port *priv = arg;
        struct uart_port *port = &priv->port;
        struct tty_struct *tty = tty_port_tty_get(&port->state->port);
+       int count;
 
        if (!tty) {
                pr_debug("%s:tty is busy now", __func__);
                return;
        }
 
-       if (dma_push_rx(priv, priv->trigger_level))
+       dma_sync_sg_for_cpu(port->dev, &priv->sg_rx, 1, DMA_FROM_DEVICE);
+       count = dma_push_rx(priv, priv->trigger_level);
+       if (count)
                tty_flip_buffer_push(tty);
-
        tty_kref_put(tty);
+       async_tx_ack(priv->desc_rx);
+       pch_uart_hal_enable_interrupt(priv, PCH_UART_HAL_RX_INT);
 }
 
 static void pch_dma_tx_complete(void *arg)
@@ -612,13 +617,21 @@ static void pch_dma_tx_complete(void *arg)
        struct eg20t_port *priv = arg;
        struct uart_port *port = &priv->port;
        struct circ_buf *xmit = &port->state->xmit;
+       struct scatterlist *sg = priv->sg_tx_p;
+       int i;
 
-       xmit->tail += sg_dma_len(&priv->sg_tx);
+       for (i = 0; i < priv->nent; i++, sg++) {
+               xmit->tail += sg_dma_len(sg);
+               port->icount.tx += sg_dma_len(sg);
+       }
        xmit->tail &= UART_XMIT_SIZE - 1;
-       port->icount.tx += sg_dma_len(&priv->sg_tx);
-
        async_tx_ack(priv->desc_tx);
+       dma_unmap_sg(port->dev, sg, priv->nent, DMA_TO_DEVICE);
        priv->tx_dma_use = 0;
+       priv->nent = 0;
+       kfree(priv->sg_tx_p);
+       if (uart_circ_chars_pending(xmit))
+               pch_uart_hal_enable_interrupt(priv, PCH_UART_HAL_TX_INT);
 }
 
 static int pop_tx(struct eg20t_port *priv, unsigned char *buf, int size)
@@ -682,7 +695,7 @@ static int dma_handle_rx(struct eg20t_port *priv)
 
        sg_init_table(&priv->sg_rx, 1); /* Initialize SG table */
 
-       sg_dma_len(sg) = priv->fifo_size;
+       sg_dma_len(sg) = priv->trigger_level;
 
        sg_set_page(&priv->sg_rx, virt_to_page(priv->rx_buf_virt),
                     sg_dma_len(sg), (unsigned long)priv->rx_buf_virt &
@@ -692,7 +705,8 @@ static int dma_handle_rx(struct eg20t_port *priv)
 
        desc = priv->chan_rx->device->device_prep_slave_sg(priv->chan_rx,
                        sg, 1, DMA_FROM_DEVICE,
-                       DMA_PREP_INTERRUPT);
+                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
        if (!desc)
                return 0;
 
@@ -731,6 +745,9 @@ static unsigned int handle_tx(struct eg20t_port *priv)
                fifo_size--;
        }
        size = min(xmit->head - xmit->tail, fifo_size);
+       if (size < 0)
+               size = fifo_size;
+
        tx_size = pop_tx(priv, xmit->buf, size);
        if (tx_size > 0) {
                ret = pch_uart_hal_write(priv, xmit->buf, tx_size);
@@ -740,8 +757,10 @@ static unsigned int handle_tx(struct eg20t_port *priv)
 
        priv->tx_empty = tx_empty;
 
-       if (tx_empty)
+       if (tx_empty) {
                pch_uart_hal_disable_interrupt(priv, PCH_UART_HAL_TX_INT);
+               uart_write_wakeup(port);
+       }
 
        return PCH_UART_HANDLED_TX_INT;
 }
@@ -750,11 +769,16 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
 {
        struct uart_port *port = &priv->port;
        struct circ_buf *xmit = &port->state->xmit;
-       struct scatterlist *sg = &priv->sg_tx;
+       struct scatterlist *sg;
        int nent;
        int fifo_size;
        int tx_empty;
        struct dma_async_tx_descriptor *desc;
+       int num;
+       int i;
+       int bytes;
+       int size;
+       int rem;
 
        if (!priv->start_tx) {
                pr_info("%s:Tx isn't started. (%lu)\n", __func__, jiffies);
@@ -772,37 +796,68 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
                fifo_size--;
        }
 
-       pch_uart_hal_disable_interrupt(priv, PCH_UART_HAL_TX_INT);
+       bytes = min((int)CIRC_CNT(xmit->head, xmit->tail,
+                            UART_XMIT_SIZE), CIRC_CNT_TO_END(xmit->head,
+                            xmit->tail, UART_XMIT_SIZE));
+       if (!bytes) {
+               pch_uart_hal_disable_interrupt(priv, PCH_UART_HAL_TX_INT);
+               uart_write_wakeup(port);
+               return 0;
+       }
+
+       if (bytes > fifo_size) {
+               num = bytes / fifo_size + 1;
+               size = fifo_size;
+               rem = bytes % fifo_size;
+       } else {
+               num = 1;
+               size = bytes;
+               rem = bytes;
+       }
 
        priv->tx_dma_use = 1;
 
-       sg_init_table(&priv->sg_tx, 1); /* Initialize SG table */
+       priv->sg_tx_p = kzalloc(sizeof(struct scatterlist)*num, GFP_ATOMIC);
+
+       sg_init_table(priv->sg_tx_p, num); /* Initialize SG table */
+       sg = priv->sg_tx_p;
 
-       sg_set_page(&priv->sg_tx, virt_to_page(xmit->buf),
-                   UART_XMIT_SIZE, (int)xmit->buf & ~PAGE_MASK);
+       for (i = 0; i < num; i++, sg++) {
+               if (i == (num - 1))
+                       sg_set_page(sg, virt_to_page(xmit->buf),
+                                   rem, fifo_size * i);
+               else
+                       sg_set_page(sg, virt_to_page(xmit->buf),
+                                   size, fifo_size * i);
+       }
 
-       nent = dma_map_sg(port->dev, &priv->sg_tx, 1, DMA_TO_DEVICE);
+       sg = priv->sg_tx_p;
+       nent = dma_map_sg(port->dev, sg, num, DMA_TO_DEVICE);
        if (!nent) {
                pr_err("%s:dma_map_sg Failed\n", __func__);
                return 0;
        }
-
-       sg->offset = xmit->tail & (UART_XMIT_SIZE - 1);
-       sg_dma_address(sg) = (sg_dma_address(sg) & ~(UART_XMIT_SIZE - 1)) +
-                             sg->offset;
-       sg_dma_len(sg) = min((int)CIRC_CNT(xmit->head, xmit->tail,
-                            UART_XMIT_SIZE), CIRC_CNT_TO_END(xmit->head,
-                            xmit->tail, UART_XMIT_SIZE));
+       priv->nent = nent;
+
+       for (i = 0; i < nent; i++, sg++) {
+               sg->offset = (xmit->tail & (UART_XMIT_SIZE - 1)) +
+                             fifo_size * i;
+               sg_dma_address(sg) = (sg_dma_address(sg) &
+                                   ~(UART_XMIT_SIZE - 1)) + sg->offset;
+               if (i == (nent - 1))
+                       sg_dma_len(sg) = rem;
+               else
+                       sg_dma_len(sg) = size;
+       }
 
        desc = priv->chan_tx->device->device_prep_slave_sg(priv->chan_tx,
-               sg, nent, DMA_TO_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+                                       priv->sg_tx_p, nent, DMA_TO_DEVICE,
+                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!desc) {
                pr_err("%s:device_prep_slave_sg Failed\n", __func__);
                return 0;
        }
-
-       dma_sync_sg_for_device(port->dev, sg, 1, DMA_TO_DEVICE);
-
+       dma_sync_sg_for_device(port->dev, priv->sg_tx_p, nent, DMA_TO_DEVICE);
        priv->desc_tx = desc;
        desc->callback = pch_dma_tx_complete;
        desc->callback_param = priv;
@@ -857,10 +912,16 @@ static irqreturn_t pch_uart_interrupt(int irq, void *dev_id)
                        }
                        break;
                case PCH_UART_IID_RDR:  /* Received Data Ready */
-                       if (priv->use_dma)
+                       if (priv->use_dma) {
+                               pch_uart_hal_disable_interrupt(priv,
+                                                       PCH_UART_HAL_RX_INT);
                                ret = dma_handle_rx(priv);
-                       else
+                               if (!ret)
+                                       pch_uart_hal_enable_interrupt(priv,
+                                                       PCH_UART_HAL_RX_INT);
+                       } else {
                                ret = handle_rx(priv);
+                       }
                        break;
                case PCH_UART_IID_RDR_TO:       /* Received Data Ready
                                                   (FIFO Timeout) */