X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=drivers%2Ftty%2Fserial%2Ffsl_lpuart.c;h=4d80fae20177948fd43652a4f1c55a7b262dba0d;hb=868a9fd9480785952336e5f119e1f75877c423a8;hp=7fd30fcc10c6238c2f3961ddc215a39a8cd61082;hpb=b349de4c91e6ad761c2beecc796615bcb64b36e6;p=platform%2Fkernel%2Flinux-starfive.git

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 7fd30fc..4d80fae 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -238,6 +238,7 @@
 
 /* Rx DMA timeout in ms, which is used to calculate Rx ring buffer size */
 #define DMA_RX_TIMEOUT		(10)
+#define DMA_RX_IDLE_CHARS	8
 #define UART_AUTOSUSPEND_TIMEOUT	3000
 
 #define DRIVER_NAME	"fsl-lpuart"
@@ -282,6 +283,7 @@ struct lpuart_port {
 	struct scatterlist	rx_sgl, tx_sgl[2];
 	struct circ_buf		rx_ring;
 	int			rx_dma_rng_buf_len;
+	int                     last_residue;
 	unsigned int		dma_tx_nents;
 	wait_queue_head_t	dma_wait;
 	bool			is_cs7; /* Set to true when character size is 7 */
@@ -331,7 +333,7 @@ static struct lpuart_soc_data imx8qxp_data = {
 	.devtype = IMX8QXP_LPUART,
 	.iotype = UPIO_MEM32,
 	.reg_off = IMX_REG_OFF,
-	.rx_watermark = 31,
+	.rx_watermark = 7, /* A lower watermark is ideal for low baud rates. */
 };
 static struct lpuart_soc_data imxrt1050_data = {
 	.devtype = IMXRT1050_LPUART,
@@ -1255,6 +1257,8 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 		sport->port.icount.rx += copied;
 	}
 
+	sport->last_residue = state.residue;
+
 exit:
 	dma_sync_sg_for_device(chan->device->dev, &sport->rx_sgl, 1,
 			       DMA_FROM_DEVICE);
@@ -1272,11 +1276,43 @@ static void lpuart_dma_rx_complete(void *arg)
 	lpuart_copy_rx_to_tty(sport);
 }
 
+/*
+ * Timer function to simulate the hardware EOP (End Of Package) event.
+ * The timer callback is to check for new RX data and copy to TTY buffer.
+ * If no new data are received since last interval, the EOP condition is
+ * met, complete the DMA transfer by copying the data. Otherwise, just
+ * restart timer.
+ */
 static void lpuart_timer_func(struct timer_list *t)
 {
 	struct lpuart_port *sport = from_timer(sport, t, lpuart_timer);
+	enum dma_status dmastat;
+	struct dma_chan *chan = sport->dma_rx_chan;
+	struct circ_buf *ring = &sport->rx_ring;
+	struct dma_tx_state state;
+	unsigned long flags;
+	int count;
 
-	lpuart_copy_rx_to_tty(sport);
+	dmastat = dmaengine_tx_status(chan, sport->dma_rx_cookie, &state);
+	if (dmastat == DMA_ERROR) {
+		dev_err(sport->port.dev, "Rx DMA transfer failed!\n");
+		return;
+	}
+
+	ring->head = sport->rx_sgl.length - state.residue;
+	count = CIRC_CNT(ring->head, ring->tail, sport->rx_sgl.length);
+
+	/* Check if new data received before copying */
+	if ((count != 0) && (sport->last_residue == state.residue))
+		lpuart_copy_rx_to_tty(sport);
+	else
+		mod_timer(&sport->lpuart_timer,
+			  jiffies + sport->dma_rx_timeout);
+
+	if (spin_trylock_irqsave(&sport->port.lock, flags)) {
+		sport->last_residue = state.residue;
+		spin_unlock_irqrestore(&sport->port.lock, flags);
+	}
 }
 
 static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
@@ -1297,9 +1333,20 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 	 */
 	sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud /  bits / 1000) * 2;
 	sport->rx_dma_rng_buf_len = (1 << fls(sport->rx_dma_rng_buf_len));
+	sport->rx_dma_rng_buf_len = max_t(int,
+					  sport->rxfifo_size * 2,
+					  sport->rx_dma_rng_buf_len);
+	/*
+	 * Keep this condition check in case rxfifo_size is unavailable
+	 * for some SoCs.
+	 */
 	if (sport->rx_dma_rng_buf_len < 16)
 		sport->rx_dma_rng_buf_len = 16;
 
+	sport->last_residue = 0;
+	sport->dma_rx_timeout = max(nsecs_to_jiffies(
+		sport->port.frame_time * DMA_RX_IDLE_CHARS), 1UL);
+
 	ring->buf = kzalloc(sport->rx_dma_rng_buf_len, GFP_ATOMIC);
 	if (!ring->buf)
 		return -ENOMEM;
@@ -1689,12 +1736,13 @@ static void lpuart_rx_dma_startup(struct lpuart_port *sport)
 	if (!sport->dma_rx_chan)
 		goto err;
 
+	/* set default Rx DMA timeout */
+	sport->dma_rx_timeout = msecs_to_jiffies(DMA_RX_TIMEOUT);
+
 	ret = lpuart_start_rx_dma(sport);
 	if (ret)
 		goto err;
 
-	/* set Rx DMA timeout */
-	sport->dma_rx_timeout = msecs_to_jiffies(DMA_RX_TIMEOUT);
 	if (!sport->dma_rx_timeout)
 		sport->dma_rx_timeout = 1;
 
@@ -2676,6 +2724,7 @@ OF_EARLYCON_DECLARE(lpuart, "fsl,vf610-lpuart", lpuart_early_console_setup);
 OF_EARLYCON_DECLARE(lpuart32, "fsl,ls1021a-lpuart", lpuart32_early_console_setup);
 OF_EARLYCON_DECLARE(lpuart32, "fsl,ls1028a-lpuart", ls1028a_early_console_setup);
 OF_EARLYCON_DECLARE(lpuart32, "fsl,imx7ulp-lpuart", lpuart32_imx_early_console_setup);
+OF_EARLYCON_DECLARE(lpuart32, "fsl,imx8ulp-lpuart", lpuart32_imx_early_console_setup);
 OF_EARLYCON_DECLARE(lpuart32, "fsl,imx8qxp-lpuart", lpuart32_imx_early_console_setup);
 OF_EARLYCON_DECLARE(lpuart32, "fsl,imxrt1050-lpuart", lpuart32_imx_early_console_setup);
 EARLYCON_DECLARE(lpuart, lpuart_early_console_setup);