1 files changed, 43 insertions, 5 deletions

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 02016fcd91b8..8d94c194f090 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -246,6 +246,7 @@ static int pl011_sgbuf_init(struct dma_chan *chan, struct pl011_sgbuf *sg,
         sg_set_page(&sg->sg, phys_to_page(dma_addr),
                 PL011_DMA_BUFFER_SIZE, offset_in_page(dma_addr));
         sg_dma_address(&sg->sg) = dma_addr;
+        sg_dma_len(&sg->sg) = PL011_DMA_BUFFER_SIZE;
 
         return 0;
 }
@@ -321,10 +322,26 @@ static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port *
                         .src_maxburst = uap->fifosize >> 2,
                         .device_fc = false,
                 };
+                struct dma_slave_caps caps;
 
+                /*
+                 * Some DMA controllers provide information on their capabilities.
+                 * If the controller does, check for suitable residue processing
+                 * otherwise assime all is well.
+                 */
+                if (0 == dma_get_slave_caps(chan, &caps)) {
+                        if (caps.residue_granularity ==
+                                        DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
+                                dma_release_channel(chan);
+                                dev_info(uap->port.dev,
+                                        "RX DMA disabled - no residue processing\n");
+                                return;
+                        }
+                }
                 dmaengine_slave_config(chan, &rx_conf);
                 uap->dmarx.chan = chan;
 
+                uap->dmarx.auto_poll_rate = false;
                 if (plat && plat->dma_rx_poll_enable) {
                         /* Set poll rate if specified. */
                         if (plat->dma_rx_poll_rate) {
@@ -345,9 +362,24 @@ static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port *
                                         plat->dma_rx_poll_timeout;
                         else
                                 uap->dmarx.poll_timeout = 3000;
-                } else
-                        uap->dmarx.auto_poll_rate = false;
-
+                } else if (!plat && dev->of_node) {
+                        uap->dmarx.auto_poll_rate = of_property_read_bool(
+                                                dev->of_node, "auto-poll");
+                        if (uap->dmarx.auto_poll_rate) {
+                                u32 x;
+
+                                if (0 == of_property_read_u32(dev->of_node,
+                                                "poll-rate-ms", &x))
+                                        uap->dmarx.poll_rate = x;
+                                else
+                                        uap->dmarx.poll_rate = 100;
+                                if (0 == of_property_read_u32(dev->of_node,
+                                                "poll-timeout-ms", &x))
+                                        uap->dmarx.poll_timeout = x;
+                                else
+                                        uap->dmarx.poll_timeout = 3000;
+                        }
+                }
                 dev_info(uap->port.dev, "DMA channel RX %s\n",
                          dma_chan_name(uap->dmarx.chan));
         }
@@ -501,7 +533,11 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap)
                 memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], count);
         else {
                 size_t first = UART_XMIT_SIZE - xmit->tail;
-                size_t second = xmit->head;
+                size_t second;
+
+                if (first > count)
+                        first = count;
+                second = count - first;
 
                 memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], first);
                 if (second)
@@ -988,7 +1024,7 @@ static void pl011_dma_startup(struct uart_amba_port *uap)
         if (!uap->dmatx.chan)
                 return;
 
-        uap->dmatx.buf = kmalloc(PL011_DMA_BUFFER_SIZE, GFP_KERNEL);
+        uap->dmatx.buf = kmalloc(PL011_DMA_BUFFER_SIZE, GFP_KERNEL | __GFP_DMA);
         if (!uap->dmatx.buf) {
                 dev_err(uap->port.dev, "no memory for DMA TX buffer\n");
                 uap->port.fifosize = uap->fifosize;
@@ -1689,6 +1725,8 @@ static void pl011_shutdown(struct uart_port *port)
                         plat->exit();
         }
 
+        if (uap->port.ops->flush_buffer)
+                uap->port.ops->flush_buffer(port);
 }
 
 static void