1 files changed, 190 insertions, 55 deletions

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index e06c6c8..f0f6ea3 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -103,6 +103,13 @@
 static int (*atmel_open_hook)(struct uart_port *);
 static void (*atmel_close_hook)(struct uart_port *);
 
+struct atmel_uart_char {
+	u16		status;
+	u16		ch;
+};
+
+#define ATMEL_SERIAL_RINGSIZE 1024
+
 /*
  * We wrap our port structure around the generic uart_port.
  */
@@ -111,6 +118,12 @@ struct atmel_uart_port {
 	struct clk		*clk;		/* uart clock */
 	unsigned short		suspended;	/* is port suspended? */
 	int			break_active;	/* break being received */
+
+	struct tasklet_struct	tasklet;
+	unsigned int		irq_status;
+	unsigned int		irq_status_prev;
+
+	struct circ_buf		rx_ring;
 };
 
 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
@@ -240,22 +253,42 @@ static void atmel_break_ctl(struct uart_port *port, int break_state)
 }
 
 /*
+ * Stores the incoming character in the ring buffer
+ */
+static void
+atmel_buffer_rx_char(struct uart_port *port, unsigned int status,
+		     unsigned int ch)
+{
+	struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
+	struct circ_buf *ring = &atmel_port->rx_ring;
+	struct atmel_uart_char *c;
+
+	if (!CIRC_SPACE(ring->head, ring->tail, ATMEL_SERIAL_RINGSIZE))
+		/* Buffer overflow, ignore char */
+		return;
+
+	c = &((struct atmel_uart_char *)ring->buf)[ring->head];
+	c->status	= status;
+	c->ch		= ch;
+
+	/* Make sure the character is stored before we update head. */
+	smp_wmb();
+
+	ring->head = (ring->head + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
+}
+
+/*
  * Characters received (called from interrupt handler)
  */
 static void atmel_rx_chars(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
-	struct tty_struct *tty = port->info->tty;
-	unsigned int status, ch, flg;
+	unsigned int status, ch;
 
 	status = UART_GET_CSR(port);
 	while (status & ATMEL_US_RXRDY) {
 		ch = UART_GET_CHAR(port);
 
-		port->icount.rx++;
-
-		flg = TTY_NORMAL;
-
 		/*
 		 * note that the error handling code is
 		 * out of the main execution path
@@ -263,17 +296,14 @@ static void atmel_rx_chars(struct uart_port *port)
 		if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
 				       | ATMEL_US_OVRE | ATMEL_US_RXBRK)
 			     || atmel_port->break_active)) {
+
 			/* clear error */
 			UART_PUT_CR(port, ATMEL_US_RSTSTA);
+
 			if (status & ATMEL_US_RXBRK
 			    && !atmel_port->break_active) {
-				/* ignore side-effect */
-				status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
-				port->icount.brk++;
 				atmel_port->break_active = 1;
 				UART_PUT_IER(port, ATMEL_US_RXBRK);
-				if (uart_handle_break(port))
-					goto ignore_char;
 			} else {
 				/*
 				 * This is either the end-of-break
@@ -286,52 +316,30 @@ static void atmel_rx_chars(struct uart_port *port)
 				status &= ~ATMEL_US_RXBRK;
 				atmel_port->break_active = 0;
 			}
-			if (status & ATMEL_US_PARE)
-				port->icount.parity++;
-			if (status & ATMEL_US_FRAME)
-				port->icount.frame++;
-			if (status & ATMEL_US_OVRE)
-				port->icount.overrun++;
-
-			status &= port->read_status_mask;
-
-			if (status & ATMEL_US_RXBRK)
-				flg = TTY_BREAK;
-			else if (status & ATMEL_US_PARE)
-				flg = TTY_PARITY;
-			else if (status & ATMEL_US_FRAME)
-				flg = TTY_FRAME;
 		}
 
-		if (uart_handle_sysrq_char(port, ch))
-			goto ignore_char;
-
-		uart_insert_char(port, status, ATMEL_US_OVRE, ch, flg);
-
-ignore_char:
+		atmel_buffer_rx_char(port, status, ch);
 		status = UART_GET_CSR(port);
 	}
 
-	tty_flip_buffer_push(tty);
+	tasklet_schedule(&atmel_port->tasklet);
 }
 
 /*
- * Transmit characters (called from interrupt handler)
+ * Transmit characters (called from tasklet with TXRDY interrupt
+ * disabled)
  */
 static void atmel_tx_chars(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->info->xmit;
 
-	if (port->x_char) {
+	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
 		UART_PUT_CHAR(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
-		return;
 	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		atmel_stop_tx(port);
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 		return;
-	}
 
 	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
@@ -344,8 +352,8 @@ static void atmel_tx_chars(struct uart_port *port)
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
-		atmel_stop_tx(port);
+	if (!uart_circ_empty(xmit))
+		UART_PUT_IER(port, ATMEL_US_TXRDY);
 }
 
 /*
@@ -371,14 +379,18 @@ atmel_handle_receive(struct uart_port *port, unsigned int pending)
 }
 
 /*
- * transmit interrupt handler.
+ * transmit interrupt handler. (Transmit is IRQF_NODELAY safe)
  */
 static void
 atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 {
+	struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
+
 	/* Interrupt transmit */
-	if (pending & ATMEL_US_TXRDY)
-		atmel_tx_chars(port);
+	if (pending & ATMEL_US_TXRDY) {
+		UART_PUT_IDR(port, ATMEL_US_TXRDY);
+		tasklet_schedule(&atmel_port->tasklet);
+	}
 }
 
 /*
@@ -388,18 +400,13 @@ static void
 atmel_handle_status(struct uart_port *port, unsigned int pending,
 		    unsigned int status)
 {
-	/* TODO: All reads to CSR will clear these interrupts! */
-	if (pending & ATMEL_US_RIIC)
-		port->icount.rng++;
-	if (pending & ATMEL_US_DSRIC)
-		port->icount.dsr++;
-	if (pending & ATMEL_US_DCDIC)
-		uart_handle_dcd_change(port, !(status & ATMEL_US_DCD));
-	if (pending & ATMEL_US_CTSIC)
-		uart_handle_cts_change(port, !(status & ATMEL_US_CTS));
+	struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
+
 	if (pending & (ATMEL_US_RIIC | ATMEL_US_DSRIC | ATMEL_US_DCDIC
-				| ATMEL_US_CTSIC))
-		wake_up_interruptible(&port->info->delta_msr_wait);
+				| ATMEL_US_CTSIC)) {
+		atmel_port->irq_status = status;
+		tasklet_schedule(&atmel_port->tasklet);
+	}
 }
 
 /*
@@ -426,6 +433,114 @@ static irqreturn_t atmel_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static void atmel_rx_from_ring(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
+	struct circ_buf *ring = &atmel_port->rx_ring;
+	unsigned int flg;
+	unsigned int status;
+
+	while (ring->head != ring->tail) {
+		struct atmel_uart_char c;
+
+		/* Make sure c is loaded after head. */
+		smp_rmb();
+
+		c = ((struct atmel_uart_char *)ring->buf)[ring->tail];
+
+		ring->tail = (ring->tail + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
+
+		port->icount.rx++;
+		status = c.status;
+		flg = TTY_NORMAL;
+
+		/*
+		 * note that the error handling code is
+		 * out of the main execution path
+		 */
+		if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
+				       | ATMEL_US_OVRE | ATMEL_US_RXBRK))) {
+			if (status & ATMEL_US_RXBRK) {
+				/* ignore side-effect */
+				status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
+
+				port->icount.brk++;
+				if (uart_handle_break(port))
+					continue;
+			}
+			if (status & ATMEL_US_PARE)
+				port->icount.parity++;
+			if (status & ATMEL_US_FRAME)
+				port->icount.frame++;
+			if (status & ATMEL_US_OVRE)
+				port->icount.overrun++;
+
+			status &= port->read_status_mask;
+
+			if (status & ATMEL_US_RXBRK)
+				flg = TTY_BREAK;
+			else if (status & ATMEL_US_PARE)
+				flg = TTY_PARITY;
+			else if (status & ATMEL_US_FRAME)
+				flg = TTY_FRAME;
+		}
+
+
+		if (uart_handle_sysrq_char(port, c.ch))
+			continue;
+
+		uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg);
+	}
+
+	/*
+	 * Drop the lock here since it might end up calling
+	 * uart_start(), which takes the lock.
+	 */
+	spin_unlock(&port->lock);
+	tty_flip_buffer_push(port->info->tty);
+	spin_lock(&port->lock);
+}
+
+/*
+ * tasklet handling tty stuff outside the interrupt handler.
+ */
+static void atmel_tasklet_func(unsigned long data)
+{
+	struct uart_port *port = (struct uart_port *)data;
+	struct atmel_uart_port *atmel_port = (struct atmel_uart_port *)port;
+	unsigned int status;
+	unsigned int status_change;
+
+	/* The interrupt handler does not take the lock */
+	spin_lock(&port->lock);
+
+	atmel_tx_chars(port);
+
+	status = atmel_port->irq_status;
+	status_change = status ^ atmel_port->irq_status_prev;
+
+	if (status_change & (ATMEL_US_RI | ATMEL_US_DSR
+				| ATMEL_US_DCD | ATMEL_US_CTS)) {
+		/* TODO: All reads to CSR will clear these interrupts! */
+		if (status_change & ATMEL_US_RI)
+			port->icount.rng++;
+		if (status_change & ATMEL_US_DSR)
+			port->icount.dsr++;
+		if (status_change & ATMEL_US_DCD)
+			uart_handle_dcd_change(port, !(status & ATMEL_US_DCD));
+		if (status_change & ATMEL_US_CTS)
+			uart_handle_cts_change(port, !(status & ATMEL_US_CTS));
+
+		wake_up_interruptible(&port->info->delta_msr_wait);
+
+		atmel_port->irq_status_prev = status;
+	}
+
+	atmel_rx_from_ring(port);
+
+	spin_unlock(&port->lock);
+}
+
 /*
  * Perform initialization and enable port for reception
  */
@@ -757,6 +872,11 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 	port->mapbase	= pdev->resource[0].start;
 	port->irq	= pdev->resource[1].start;
 
+	tasklet_init(&atmel_port->tasklet, atmel_tasklet_func,
+			(unsigned long)port);
+
+	memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));
+
 	if (data->regs)
 		/* Already mapped by setup code */
 		port->membase = data->regs;
@@ -997,11 +1117,20 @@ static int atmel_serial_resume(struct platform_device *pdev)
 static int __devinit atmel_serial_probe(struct platform_device *pdev)
 {
 	struct atmel_uart_port *port;
+	void *data;
 	int ret;
 
+	BUILD_BUG_ON(!is_power_of_2(ATMEL_SERIAL_RINGSIZE));
+
 	port = &atmel_ports[pdev->id];
 	atmel_init_port(port, pdev);
 
+	ret = -ENOMEM;
+	data = kmalloc(ATMEL_SERIAL_RINGSIZE, GFP_KERNEL);
+	if (!data)
+		goto err_alloc_ring;
+	port->rx_ring.buf = data;
+
 	ret = uart_add_one_port(&atmel_uart, &port->uart);
 	if (ret)
 		goto err_add_port;
@@ -1012,6 +1141,9 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev)
 	return 0;
 
 err_add_port:
+	kfree(port->rx_ring.buf);
+	port->rx_ring.buf = NULL;
+err_alloc_ring:
 	if (!atmel_is_console_port(&port->uart)) {
 		clk_disable(port->clk);
 		clk_put(port->clk);
@@ -1032,6 +1164,9 @@ static int __devexit atmel_serial_remove(struct platform_device *pdev)
 
 	ret = uart_remove_one_port(&atmel_uart, port);
 
+	tasklet_kill(&atmel_port->tasklet);
+	kfree(atmel_port->rx_ring.buf);
+
 	/* "port" is allocated statically, so we shouldn't free it */
 
 	clk_disable(atmel_port->clk);