[PATCH LINUX 0/6] Second part of xuartps fixes

[PATCH LINUX 0/6] Second part of xuartps fixes

[Soren Brinkmann]

Hi,

this is the second part of fixes for xuartps that evolved from this
series: https://lkml.org/lkml/2015/12/26/26.

This series, obviously, depends on the patches mentioned above. It
includes several minor improvements and refactoring and the refactoring
of the IRQ management, which prevents lock ups that could happen when
RX-related IRQs fired while the receiver was disabled.

	Thanks,
	Sören

Sören Brinkmann (6):
  tty: xuartps: Move request_irq to after setting up the HW
  tty: xuartps: Refactor IRQ handling
  tty: xuartps: Cleanup: Reformat if-else
  tty: xuartps: Improve sysrq handling
  tty: xuartps: Remove '_OFFSET' suffix from #defines
  tty: xuartps: Consolidate TX handling

 drivers/tty/serial/xilinx_uartps.c | 460 +++++++++++++++++--------------------
 1 file changed, 216 insertions(+), 244 deletions(-)

-- 
2.7.0.3.g497ea1e


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[PATCH LINUX 1/6] tty: xuartps: Move request_irq to after setting up the HW

[Soren Brinkmann]

Request_irq() should be _after_ h/w programming, otherwise an
interrupt could be triggered and in-progress before the h/w has been
setup.

Reported-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index db9e23eaf300..5da1c51e9e40 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -762,13 +762,9 @@ static void cdns_uart_set_termios(struct uart_port *port,
  */
 static int cdns_uart_startup(struct uart_port *port)
 {
+	int ret;
 	unsigned long flags;
-	unsigned int retval = 0, status = 0;
-
-	retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
-								(void *)port);
-	if (retval)
-		return retval;
+	unsigned int status = 0;
 
 	spin_lock_irqsave(&port->lock, flags);
 
@@ -814,15 +810,22 @@ static int cdns_uart_startup(struct uart_port *port)
 	writel(readl(port->membase + CDNS_UART_ISR_OFFSET),
 			port->membase + CDNS_UART_ISR_OFFSET);
 
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	ret = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME, port);
+	if (ret) {
+		dev_err(port->dev, "request_irq '%d' failed with %d\n",
+			port->irq, ret);
+		return ret;
+	}
+
 	/* Set the Interrupt Registers with desired interrupts */
 	writel(CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_PARITY |
 		CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN |
 		CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
 		port->membase + CDNS_UART_IER_OFFSET);
 
-	spin_unlock_irqrestore(&port->lock, flags);
-
-	return retval;
+	return 0;
 }
 
 /**
-- 
2.7.0.3.g497ea1e

[PATCH LINUX 2/6] tty: xuartps: Refactor IRQ handling

[Soren Brinkmann]

The system could deadlock handling RX IRQs when RX-related IRQ
conditions became true while the receiver was disabled. To avoid this,
enable/disable the RX/TX IRQs together with the receiver/transmitter.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 5da1c51e9e40..a0039cbcf812 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -126,6 +126,10 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
 #define CDNS_UART_IXR_RXEMPTY	0x00000002 /* RX FIFO empty interrupt. */
 #define CDNS_UART_IXR_MASK	0x00001FFF /* Valid bit mask */
 
+#define CDNS_UART_RX_IRQS	(CDNS_UART_IXR_PARITY | CDNS_UART_IXR_FRAMING | \
+				 CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_RXTRIG | \
+				 CDNS_UART_IXR_TOUT)
+
 /* Goes in read_status_mask for break detection as the HW doesn't do it*/
 #define CDNS_UART_IXR_BRK	0x80000000
 
@@ -272,7 +276,8 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 	 */
 	isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
 
-	cdns_uart_handle_rx(port, isrstatus);
+	if (isrstatus & CDNS_UART_RX_IRQS)
+		cdns_uart_handle_rx(port, isrstatus);
 
 	/* Dispatch an appropriate handler */
 	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
@@ -580,9 +585,12 @@ static void cdns_uart_stop_rx(struct uart_port *port)
 {
 	unsigned int regval;
 
+	/* Disable RX IRQs */
+	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IDR_OFFSET);
+
+	/* Disable the receiver */
 	regval = readl(port->membase + CDNS_UART_CR_OFFSET);
 	regval |= CDNS_UART_CR_RX_DIS;
-	/* Disable the receiver */
 	writel(regval, port->membase + CDNS_UART_CR_OFFSET);
 }
 
@@ -820,10 +828,7 @@ static int cdns_uart_startup(struct uart_port *port)
 	}
 
 	/* Set the Interrupt Registers with desired interrupts */
-	writel(CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_PARITY |
-		CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN |
-		CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
-		port->membase + CDNS_UART_IER_OFFSET);
+	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER_OFFSET);
 
 	return 0;
 }
-- 
2.7.0.3.g497ea1e

[PATCH LINUX 3/6] tty: xuartps: Cleanup: Reformat if-else

[Soren Brinkmann]

Convert an if-else into the more common early return on error, reducing
the indent level of the happy path.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 124 ++++++++++++++++++-------------------
 1 file changed, 62 insertions(+), 62 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index a0039cbcf812..8014dd3c6d55 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -202,58 +202,55 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
 	isrstatus &= port->read_status_mask;
 	isrstatus &= ~port->ignore_status_mask;
 
-	if ((isrstatus & CDNS_UART_IXR_TOUT) ||
-		(isrstatus & CDNS_UART_IXR_RXTRIG)) {
-		/* Receive Timeout Interrupt */
-		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-					CDNS_UART_SR_RXEMPTY)) {
-			u32 data;
-			char status = TTY_NORMAL;
-
-			data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
-
-			/* Non-NULL byte after BREAK is garbage (99%) */
-			if (data && (port->read_status_mask &
-						CDNS_UART_IXR_BRK)) {
-				port->read_status_mask &= ~CDNS_UART_IXR_BRK;
-				port->icount.brk++;
-				if (uart_handle_break(port))
-					continue;
-			}
+	if (!(isrstatus & (CDNS_UART_IXR_TOUT | CDNS_UART_IXR_RXTRIG)))
+		return;
+
+	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
+				CDNS_UART_SR_RXEMPTY)) {
+		u32 data;
+		char status = TTY_NORMAL;
+
+		data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
+
+		/* Non-NULL byte after BREAK is garbage (99%) */
+		if (data && (port->read_status_mask & CDNS_UART_IXR_BRK)) {
+			port->read_status_mask &= ~CDNS_UART_IXR_BRK;
+			port->icount.brk++;
+			if (uart_handle_break(port))
+				continue;
+		}
 
 #ifdef SUPPORT_SYSRQ
-			/*
-			 * uart_handle_sysrq_char() doesn't work if
-			 * spinlocked, for some reason
-			 */
-			 if (port->sysrq) {
-				spin_unlock(&port->lock);
-				if (uart_handle_sysrq_char(port,
-							(unsigned char)data)) {
-					spin_lock(&port->lock);
-					continue;
-				}
+		/*
+		 * uart_handle_sysrq_char() doesn't work if
+		 * spinlocked, for some reason
+		 */
+		 if (port->sysrq) {
+			spin_unlock(&port->lock);
+			if (uart_handle_sysrq_char(port, data)) {
 				spin_lock(&port->lock);
+				continue;
 			}
+			spin_lock(&port->lock);
+		}
 #endif
 
-			port->icount.rx++;
-
-			if (isrstatus & CDNS_UART_IXR_PARITY) {
-				port->icount.parity++;
-				status = TTY_PARITY;
-			} else if (isrstatus & CDNS_UART_IXR_FRAMING) {
-				port->icount.frame++;
-				status = TTY_FRAME;
-			} else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
-				port->icount.overrun++;
-			}
+		port->icount.rx++;
 
-			uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
-					 data, status);
+		if (isrstatus & CDNS_UART_IXR_PARITY) {
+			port->icount.parity++;
+			status = TTY_PARITY;
+		} else if (isrstatus & CDNS_UART_IXR_FRAMING) {
+			port->icount.frame++;
+			status = TTY_FRAME;
+		} else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
+			port->icount.overrun++;
 		}
-		tty_flip_buffer_push(&port->state->port);
+
+		uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
+				 data, status);
 	}
+	tty_flip_buffer_push(&port->state->port);
 }
 
 /**
@@ -1429,27 +1426,30 @@ static int cdns_uart_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "Cannot get uart_port structure\n");
 		rc = -ENODEV;
 		goto err_out_notif_unreg;
-	} else {
-		/* Register the port.
-		 * This function also registers this device with the tty layer
-		 * and triggers invocation of the config_port() entry point.
-		 */
-		port->mapbase = res->start;
-		port->irq = irq;
-		port->dev = &pdev->dev;
-		port->uartclk = clk_get_rate(cdns_uart_data->uartclk);
-		port->private_data = cdns_uart_data;
-		cdns_uart_data->port = port;
-		platform_set_drvdata(pdev, port);
-		rc = uart_add_one_port(&cdns_uart_uart_driver, port);
-		if (rc) {
-			dev_err(&pdev->dev,
-				"uart_add_one_port() failed; err=%i\n", rc);
-			goto err_out_notif_unreg;
-		}
-		return 0;
 	}
 
+	/*
+	 * Register the port.
+	 * This function also registers this device with the tty layer
+	 * and triggers invocation of the config_port() entry point.
+	 */
+	port->mapbase = res->start;
+	port->irq = irq;
+	port->dev = &pdev->dev;
+	port->uartclk = clk_get_rate(cdns_uart_data->uartclk);
+	port->private_data = cdns_uart_data;
+	cdns_uart_data->port = port;
+	platform_set_drvdata(pdev, port);
+
+	rc = uart_add_one_port(&cdns_uart_uart_driver, port);
+	if (rc) {
+		dev_err(&pdev->dev,
+			"uart_add_one_port() failed; err=%i\n", rc);
+		goto err_out_notif_unreg;
+	}
+
+	return 0;
+
 err_out_notif_unreg:
 #ifdef CONFIG_COMMON_CLK
 	clk_notifier_unregister(cdns_uart_data->uartclk,
-- 
2.7.0.3.g497ea1e

[PATCH LINUX 4/6] tty: xuartps: Improve sysrq handling

[Soren Brinkmann]

Handling magic sysrq included dropping a lock to avoid a deadlock that
happened when cdns_uart_console_write tried to acquire a lock in the
from the sysrq code path. By making the acquisition of the lock in
cdns_uart_console_write depending on port->sysrq, cdns_uart_handle_rx can be
simplified to simply call uart_handle_sysrq.

Suggested-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
v4:
 - added this patch
---
 drivers/tty/serial/xilinx_uartps.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 8014dd3c6d55..0eecba88298f 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -220,20 +220,8 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
 				continue;
 		}
 
-#ifdef SUPPORT_SYSRQ
-		/*
-		 * uart_handle_sysrq_char() doesn't work if
-		 * spinlocked, for some reason
-		 */
-		 if (port->sysrq) {
-			spin_unlock(&port->lock);
-			if (uart_handle_sysrq_char(port, data)) {
-				spin_lock(&port->lock);
-				continue;
-			}
-			spin_lock(&port->lock);
-		}
-#endif
+		if (uart_handle_sysrq_char(port, data))
+			continue;
 
 		port->icount.rx++;
 
@@ -1128,7 +1116,9 @@ static void cdns_uart_console_write(struct console *co, const char *s,
 	unsigned int imr, ctrl;
 	int locked = 1;
 
-	if (oops_in_progress)
+	if (port->sysrq)
+		locked = 0;
+	else if (oops_in_progress)
 		locked = spin_trylock_irqsave(&port->lock, flags);
 	else
 		spin_lock_irqsave(&port->lock, flags);
-- 
2.7.0.3.g497ea1e

[PATCH LINUX 5/6] tty: xuartps: Remove '_OFFSET' suffix from #defines

[Soren Brinkmann]

Remove the _OFFSET suffix from all register defines which makes code a
little easier to read and avoids a few line breaks.

Suggested-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
v4:
 - added this patch
---
 drivers/tty/serial/xilinx_uartps.c | 221 ++++++++++++++++++-------------------
 1 file changed, 106 insertions(+), 115 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 0eecba88298f..3ff6e3c2347c 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -50,24 +50,24 @@ module_param(rx_timeout, uint, S_IRUGO);
 MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
 
 /* Register offsets for the UART. */
-#define CDNS_UART_CR_OFFSET		0x00  /* Control Register */
-#define CDNS_UART_MR_OFFSET		0x04  /* Mode Register */
-#define CDNS_UART_IER_OFFSET		0x08  /* Interrupt Enable */
-#define CDNS_UART_IDR_OFFSET		0x0C  /* Interrupt Disable */
-#define CDNS_UART_IMR_OFFSET		0x10  /* Interrupt Mask */
-#define CDNS_UART_ISR_OFFSET		0x14  /* Interrupt Status */
-#define CDNS_UART_BAUDGEN_OFFSET	0x18  /* Baud Rate Generator */
-#define CDNS_UART_RXTOUT_OFFSET		0x1C  /* RX Timeout */
-#define CDNS_UART_RXWM_OFFSET		0x20  /* RX FIFO Trigger Level */
-#define CDNS_UART_MODEMCR_OFFSET	0x24  /* Modem Control */
-#define CDNS_UART_MODEMSR_OFFSET	0x28  /* Modem Status */
-#define CDNS_UART_SR_OFFSET		0x2C  /* Channel Status */
-#define CDNS_UART_FIFO_OFFSET		0x30  /* FIFO */
-#define CDNS_UART_BAUDDIV_OFFSET	0x34  /* Baud Rate Divider */
-#define CDNS_UART_FLOWDEL_OFFSET	0x38  /* Flow Delay */
-#define CDNS_UART_IRRX_PWIDTH_OFFSET	0x3C  /* IR Min Received Pulse Width */
-#define CDNS_UART_IRTX_PWIDTH_OFFSET	0x40  /* IR Transmitted pulse Width */
-#define CDNS_UART_TXWM_OFFSET		0x44  /* TX FIFO Trigger Level */
+#define CDNS_UART_CR		0x00  /* Control Register */
+#define CDNS_UART_MR		0x04  /* Mode Register */
+#define CDNS_UART_IER		0x08  /* Interrupt Enable */
+#define CDNS_UART_IDR		0x0C  /* Interrupt Disable */
+#define CDNS_UART_IMR		0x10  /* Interrupt Mask */
+#define CDNS_UART_ISR		0x14  /* Interrupt Status */
+#define CDNS_UART_BAUDGEN	0x18  /* Baud Rate Generator */
+#define CDNS_UART_RXTOUT		0x1C  /* RX Timeout */
+#define CDNS_UART_RXWM		0x20  /* RX FIFO Trigger Level */
+#define CDNS_UART_MODEMCR	0x24  /* Modem Control */
+#define CDNS_UART_MODEMSR	0x28  /* Modem Status */
+#define CDNS_UART_SR		0x2C  /* Channel Status */
+#define CDNS_UART_FIFO		0x30  /* FIFO */
+#define CDNS_UART_BAUDDIV	0x34  /* Baud Rate Divider */
+#define CDNS_UART_FLOWDEL	0x38  /* Flow Delay */
+#define CDNS_UART_IRRX_PWIDTH	0x3C  /* IR Min Received Pulse Width */
+#define CDNS_UART_IRTX_PWIDTH	0x40  /* IR Transmitted pulse Width */
+#define CDNS_UART_TXWM		0x44  /* TX FIFO Trigger Level */
 
 /* Control Register Bit Definitions */
 #define CDNS_UART_CR_STOPBRK	0x00000100  /* Stop TX break */
@@ -184,15 +184,14 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
 	 * there's another non-zero byte at the end of the sequence.
 	 */
 	if (isrstatus & CDNS_UART_IXR_FRAMING) {
-		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
+		while (!(readl(port->membase + CDNS_UART_SR) &
 					CDNS_UART_SR_RXEMPTY)) {
-			if (!readl(port->membase + CDNS_UART_FIFO_OFFSET)) {
+			if (!readl(port->membase + CDNS_UART_FIFO)) {
 				port->read_status_mask |= CDNS_UART_IXR_BRK;
 				isrstatus &= ~CDNS_UART_IXR_FRAMING;
 			}
 		}
-		writel(CDNS_UART_IXR_FRAMING,
-				port->membase + CDNS_UART_ISR_OFFSET);
+		writel(CDNS_UART_IXR_FRAMING, port->membase + CDNS_UART_ISR);
 	}
 
 	/* drop byte with parity error if IGNPAR specified */
@@ -205,12 +204,11 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
 	if (!(isrstatus & (CDNS_UART_IXR_TOUT | CDNS_UART_IXR_RXTRIG)))
 		return;
 
-	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-				CDNS_UART_SR_RXEMPTY)) {
+	while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_RXEMPTY)) {
 		u32 data;
 		char status = TTY_NORMAL;
 
-		data = readl(port->membase + CDNS_UART_FIFO_OFFSET);
+		data = readl(port->membase + CDNS_UART_FIFO);
 
 		/* Non-NULL byte after BREAK is garbage (99%) */
 		if (data && (port->read_status_mask & CDNS_UART_IXR_BRK)) {
@@ -259,7 +257,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 	/* Read the interrupt status register to determine which
 	 * interrupt(s) is/are active.
 	 */
-	isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
+	isrstatus = readl(port->membase + CDNS_UART_ISR);
 
 	if (isrstatus & CDNS_UART_RX_IRQS)
 		cdns_uart_handle_rx(port, isrstatus);
@@ -268,7 +266,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
 		if (uart_circ_empty(&port->state->xmit)) {
 			writel(CDNS_UART_IXR_TXEMPTY,
-					port->membase + CDNS_UART_IDR_OFFSET);
+					port->membase + CDNS_UART_IDR);
 		} else {
 			numbytes = port->fifosize;
 			/* Break if no more data available in the UART buffer */
@@ -281,7 +279,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 				 */
 				writel(port->state->xmit.buf[
 						port->state->xmit.tail],
-					port->membase + CDNS_UART_FIFO_OFFSET);
+					port->membase + CDNS_UART_FIFO);
 
 				port->icount.tx++;
 
@@ -299,7 +297,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 		}
 	}
 
-	writel(isrstatus, port->membase + CDNS_UART_ISR_OFFSET);
+	writel(isrstatus, port->membase + CDNS_UART_ISR);
 
 	/* be sure to release the lock and tty before leaving */
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -389,14 +387,14 @@ static unsigned int cdns_uart_set_baud_rate(struct uart_port *port,
 			&div8);
 
 	/* Write new divisors to hardware */
-	mreg = readl(port->membase + CDNS_UART_MR_OFFSET);
+	mreg = readl(port->membase + CDNS_UART_MR);
 	if (div8)
 		mreg |= CDNS_UART_MR_CLKSEL;
 	else
 		mreg &= ~CDNS_UART_MR_CLKSEL;
-	writel(mreg, port->membase + CDNS_UART_MR_OFFSET);
-	writel(cd, port->membase + CDNS_UART_BAUDGEN_OFFSET);
-	writel(bdiv, port->membase + CDNS_UART_BAUDDIV_OFFSET);
+	writel(mreg, port->membase + CDNS_UART_MR);
+	writel(cd, port->membase + CDNS_UART_BAUDGEN);
+	writel(bdiv, port->membase + CDNS_UART_BAUDDIV);
 	cdns_uart->baud = baud;
 
 	return calc_baud;
@@ -443,9 +441,9 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb,
 		spin_lock_irqsave(&cdns_uart->port->lock, flags);
 
 		/* Disable the TX and RX to set baud rate */
-		ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+		ctrl_reg = readl(port->membase + CDNS_UART_CR);
 		ctrl_reg |= CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS;
-		writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+		writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
 		spin_unlock_irqrestore(&cdns_uart->port->lock, flags);
 
@@ -470,11 +468,11 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb,
 			spin_lock_irqsave(&cdns_uart->port->lock, flags);
 
 		/* Set TX/RX Reset */
-		ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+		ctrl_reg = readl(port->membase + CDNS_UART_CR);
 		ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
-		writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+		writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
-		while (readl(port->membase + CDNS_UART_CR_OFFSET) &
+		while (readl(port->membase + CDNS_UART_CR) &
 				(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST))
 			cpu_relax();
 
@@ -483,11 +481,11 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb,
 		 * enable bit and RX enable bit to enable the transmitter and
 		 * receiver.
 		 */
-		writel(rx_timeout, port->membase + CDNS_UART_RXTOUT_OFFSET);
-		ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+		writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);
+		ctrl_reg = readl(port->membase + CDNS_UART_CR);
 		ctrl_reg &= ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS);
 		ctrl_reg |= CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN;
-		writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+		writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
 		spin_unlock_irqrestore(&cdns_uart->port->lock, flags);
 
@@ -513,15 +511,15 @@ static void cdns_uart_start_tx(struct uart_port *port)
 	 * Set the TX enable bit and clear the TX disable bit to enable the
 	 * transmitter.
 	 */
-	status = readl(port->membase + CDNS_UART_CR_OFFSET);
+	status = readl(port->membase + CDNS_UART_CR);
 	status &= ~CDNS_UART_CR_TX_DIS;
 	status |= CDNS_UART_CR_TX_EN;
-	writel(status, port->membase + CDNS_UART_CR_OFFSET);
+	writel(status, port->membase + CDNS_UART_CR);
 
 	if (uart_circ_empty(&port->state->xmit))
 		return;
 
-	while (numbytes-- && ((readl(port->membase + CDNS_UART_SR_OFFSET) &
+	while (numbytes-- && ((readl(port->membase + CDNS_UART_SR) &
 				CDNS_UART_SR_TXFULL)) != CDNS_UART_SR_TXFULL) {
 		/* Break if no more data available in the UART buffer */
 		if (uart_circ_empty(&port->state->xmit))
@@ -531,7 +529,7 @@ static void cdns_uart_start_tx(struct uart_port *port)
 		 * write it to the cdns_uart's TX_FIFO register.
 		 */
 		writel(port->state->xmit.buf[port->state->xmit.tail],
-				port->membase + CDNS_UART_FIFO_OFFSET);
+				port->membase + CDNS_UART_FIFO);
 		port->icount.tx++;
 
 		/* Adjust the tail of the UART buffer and wrap
@@ -540,9 +538,9 @@ static void cdns_uart_start_tx(struct uart_port *port)
 		port->state->xmit.tail = (port->state->xmit.tail + 1) &
 					(UART_XMIT_SIZE - 1);
 	}
-	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR_OFFSET);
+	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR);
 	/* Enable the TX Empty interrupt */
-	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER_OFFSET);
+	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER);
 
 	if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
@@ -556,10 +554,10 @@ static void cdns_uart_stop_tx(struct uart_port *port)
 {
 	unsigned int regval;
 
-	regval = readl(port->membase + CDNS_UART_CR_OFFSET);
+	regval = readl(port->membase + CDNS_UART_CR);
 	regval |= CDNS_UART_CR_TX_DIS;
 	/* Disable the transmitter */
-	writel(regval, port->membase + CDNS_UART_CR_OFFSET);
+	writel(regval, port->membase + CDNS_UART_CR);
 }
 
 /**
@@ -571,12 +569,12 @@ static void cdns_uart_stop_rx(struct uart_port *port)
 	unsigned int regval;
 
 	/* Disable RX IRQs */
-	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IDR_OFFSET);
+	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IDR);
 
 	/* Disable the receiver */
-	regval = readl(port->membase + CDNS_UART_CR_OFFSET);
+	regval = readl(port->membase + CDNS_UART_CR);
 	regval |= CDNS_UART_CR_RX_DIS;
-	writel(regval, port->membase + CDNS_UART_CR_OFFSET);
+	writel(regval, port->membase + CDNS_UART_CR);
 }
 
 /**
@@ -589,7 +587,7 @@ static unsigned int cdns_uart_tx_empty(struct uart_port *port)
 {
 	unsigned int status;
 
-	status = readl(port->membase + CDNS_UART_SR_OFFSET) &
+	status = readl(port->membase + CDNS_UART_SR) &
 				CDNS_UART_SR_TXEMPTY;
 	return status ? TIOCSER_TEMT : 0;
 }
@@ -607,15 +605,15 @@ static void cdns_uart_break_ctl(struct uart_port *port, int ctl)
 
 	spin_lock_irqsave(&port->lock, flags);
 
-	status = readl(port->membase + CDNS_UART_CR_OFFSET);
+	status = readl(port->membase + CDNS_UART_CR);
 
 	if (ctl == -1)
 		writel(CDNS_UART_CR_STARTBRK | status,
-				port->membase + CDNS_UART_CR_OFFSET);
+				port->membase + CDNS_UART_CR);
 	else {
 		if ((status & CDNS_UART_CR_STOPBRK) == 0)
 			writel(CDNS_UART_CR_STOPBRK | status,
-					port->membase + CDNS_UART_CR_OFFSET);
+					port->membase + CDNS_UART_CR);
 	}
 	spin_unlock_irqrestore(&port->lock, flags);
 }
@@ -638,18 +636,18 @@ static void cdns_uart_set_termios(struct uart_port *port,
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Wait for the transmit FIFO to empty before making changes */
-	if (!(readl(port->membase + CDNS_UART_CR_OFFSET) &
+	if (!(readl(port->membase + CDNS_UART_CR) &
 				CDNS_UART_CR_TX_DIS)) {
-		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
+		while (!(readl(port->membase + CDNS_UART_SR) &
 				CDNS_UART_SR_TXEMPTY)) {
 			cpu_relax();
 		}
 	}
 
 	/* Disable the TX and RX to set baud rate */
-	ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+	ctrl_reg = readl(port->membase + CDNS_UART_CR);
 	ctrl_reg |= CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS;
-	writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+	writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
 	/*
 	 * Min baud rate = 6bps and Max Baud Rate is 10Mbps for 100Mhz clk
@@ -668,20 +666,20 @@ static void cdns_uart_set_termios(struct uart_port *port,
 	uart_update_timeout(port, termios->c_cflag, baud);
 
 	/* Set TX/RX Reset */
-	ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+	ctrl_reg = readl(port->membase + CDNS_UART_CR);
 	ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
-	writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+	writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
 	/*
 	 * Clear the RX disable and TX disable bits and then set the TX enable
 	 * bit and RX enable bit to enable the transmitter and receiver.
 	 */
-	ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+	ctrl_reg = readl(port->membase + CDNS_UART_CR);
 	ctrl_reg &= ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS);
 	ctrl_reg |= CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN;
-	writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+	writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
-	writel(rx_timeout, port->membase + CDNS_UART_RXTOUT_OFFSET);
+	writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);
 
 	port->read_status_mask = CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_RXTRIG |
 			CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_TOUT;
@@ -701,7 +699,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
 			CDNS_UART_IXR_TOUT | CDNS_UART_IXR_PARITY |
 			CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN;
 
-	mode_reg = readl(port->membase + CDNS_UART_MR_OFFSET);
+	mode_reg = readl(port->membase + CDNS_UART_MR);
 
 	/* Handling Data Size */
 	switch (termios->c_cflag & CSIZE) {
@@ -742,7 +740,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
 		cval |= CDNS_UART_MR_PARITY_NONE;
 	}
 	cval |= mode_reg & 1;
-	writel(cval, port->membase + CDNS_UART_MR_OFFSET);
+	writel(cval, port->membase + CDNS_UART_MR);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 }
@@ -763,45 +761,45 @@ static int cdns_uart_startup(struct uart_port *port)
 
 	/* Disable the TX and RX */
 	writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
-			port->membase + CDNS_UART_CR_OFFSET);
+			port->membase + CDNS_UART_CR);
 
 	/* Set the Control Register with TX/RX Enable, TX/RX Reset,
 	 * no break chars.
 	 */
 	writel(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST,
-			port->membase + CDNS_UART_CR_OFFSET);
+			port->membase + CDNS_UART_CR);
 
 	/*
 	 * Clear the RX disable bit and then set the RX enable bit to enable
 	 * the receiver.
 	 */
-	status = readl(port->membase + CDNS_UART_CR_OFFSET);
+	status = readl(port->membase + CDNS_UART_CR);
 	status &= CDNS_UART_CR_RX_DIS;
 	status |= CDNS_UART_CR_RX_EN;
-	writel(status, port->membase + CDNS_UART_CR_OFFSET);
+	writel(status, port->membase + CDNS_UART_CR);
 
 	/* Set the Mode Register with normal mode,8 data bits,1 stop bit,
 	 * no parity.
 	 */
 	writel(CDNS_UART_MR_CHMODE_NORM | CDNS_UART_MR_STOPMODE_1_BIT
 		| CDNS_UART_MR_PARITY_NONE | CDNS_UART_MR_CHARLEN_8_BIT,
-		port->membase + CDNS_UART_MR_OFFSET);
+		port->membase + CDNS_UART_MR);
 
 	/*
 	 * Set the RX FIFO Trigger level to use most of the FIFO, but it
 	 * can be tuned with a module parameter
 	 */
-	writel(rx_trigger_level, port->membase + CDNS_UART_RXWM_OFFSET);
+	writel(rx_trigger_level, port->membase + CDNS_UART_RXWM);
 
 	/*
 	 * Receive Timeout register is enabled but it
 	 * can be tuned with a module parameter
 	 */
-	writel(rx_timeout, port->membase + CDNS_UART_RXTOUT_OFFSET);
+	writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);
 
 	/* Clear out any pending interrupts before enabling them */
-	writel(readl(port->membase + CDNS_UART_ISR_OFFSET),
-			port->membase + CDNS_UART_ISR_OFFSET);
+	writel(readl(port->membase + CDNS_UART_ISR),
+			port->membase + CDNS_UART_ISR);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
@@ -813,7 +811,7 @@ static int cdns_uart_startup(struct uart_port *port)
 	}
 
 	/* Set the Interrupt Registers with desired interrupts */
-	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER_OFFSET);
+	writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER);
 
 	return 0;
 }
@@ -830,13 +828,13 @@ static void cdns_uart_shutdown(struct uart_port *port)
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Disable interrupts */
-	status = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(status, port->membase + CDNS_UART_IDR_OFFSET);
-	writel(0xffffffff, port->membase + CDNS_UART_ISR_OFFSET);
+	status = readl(port->membase + CDNS_UART_IMR);
+	writel(status, port->membase + CDNS_UART_IDR);
+	writel(0xffffffff, port->membase + CDNS_UART_ISR);
 
 	/* Disable the TX and RX */
 	writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
-			port->membase + CDNS_UART_CR_OFFSET);
+			port->membase + CDNS_UART_CR);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
@@ -941,7 +939,7 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	u32 val;
 
-	val = readl(port->membase + CDNS_UART_MODEMCR_OFFSET);
+	val = readl(port->membase + CDNS_UART_MODEMCR);
 
 	val &= ~(CDNS_UART_MODEMCR_RTS | CDNS_UART_MODEMCR_DTR);
 
@@ -950,7 +948,7 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	if (mctrl & TIOCM_DTR)
 		val |= CDNS_UART_MODEMCR_DTR;
 
-	writel(val, port->membase + CDNS_UART_MODEMCR_OFFSET);
+	writel(val, port->membase + CDNS_UART_MODEMCR);
 }
 
 #ifdef CONFIG_CONSOLE_POLL
@@ -962,11 +960,10 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Check if FIFO is empty */
-	if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
+	if (readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_RXEMPTY)
 		c = NO_POLL_CHAR;
 	else /* Read a character */
-		c = (unsigned char) readl(
-					port->membase + CDNS_UART_FIFO_OFFSET);
+		c = (unsigned char) readl(port->membase + CDNS_UART_FIFO);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
@@ -980,16 +977,14 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Wait until FIFO is empty */
-	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-				CDNS_UART_SR_TXEMPTY))
+	while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXEMPTY))
 		cpu_relax();
 
 	/* Write a character */
-	writel(c, port->membase + CDNS_UART_FIFO_OFFSET);
+	writel(c, port->membase + CDNS_UART_FIFO);
 
 	/* Wait until FIFO is empty */
-	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-				CDNS_UART_SR_TXEMPTY))
+	while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXEMPTY))
 		cpu_relax();
 
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -1066,8 +1061,7 @@ static struct uart_port *cdns_uart_get_port(int id)
  */
 static void cdns_uart_console_wait_tx(struct uart_port *port)
 {
-	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
-				CDNS_UART_SR_TXEMPTY))
+	while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXEMPTY))
 		barrier();
 }
 
@@ -1079,7 +1073,7 @@ static void cdns_uart_console_wait_tx(struct uart_port *port)
 static void cdns_uart_console_putchar(struct uart_port *port, int ch)
 {
 	cdns_uart_console_wait_tx(port);
-	writel(ch, port->membase + CDNS_UART_FIFO_OFFSET);
+	writel(ch, port->membase + CDNS_UART_FIFO);
 }
 
 static void __init cdns_early_write(struct console *con, const char *s,
@@ -1124,25 +1118,25 @@ static void cdns_uart_console_write(struct console *co, const char *s,
 		spin_lock_irqsave(&port->lock, flags);
 
 	/* save and disable interrupt */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	imr = readl(port->membase + CDNS_UART_IMR);
+	writel(imr, port->membase + CDNS_UART_IDR);
 
 	/*
 	 * Make sure that the tx part is enabled. Set the TX enable bit and
 	 * clear the TX disable bit to enable the transmitter.
 	 */
-	ctrl = readl(port->membase + CDNS_UART_CR_OFFSET);
+	ctrl = readl(port->membase + CDNS_UART_CR);
 	ctrl &= ~CDNS_UART_CR_TX_DIS;
 	ctrl |= CDNS_UART_CR_TX_EN;
-	writel(ctrl, port->membase + CDNS_UART_CR_OFFSET);
+	writel(ctrl, port->membase + CDNS_UART_CR);
 
 	uart_console_write(port, s, count, cdns_uart_console_putchar);
 	cdns_uart_console_wait_tx(port);
 
-	writel(ctrl, port->membase + CDNS_UART_CR_OFFSET);
+	writel(ctrl, port->membase + CDNS_UART_CR);
 
 	/* restore interrupt state */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	writel(imr, port->membase + CDNS_UART_IER);
 
 	if (locked)
 		spin_unlock_irqrestore(&port->lock, flags);
@@ -1254,14 +1248,13 @@ static int cdns_uart_suspend(struct device *device)
 
 		spin_lock_irqsave(&port->lock, flags);
 		/* Empty the receive FIFO 1st before making changes */
-		while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
+		while (!(readl(port->membase + CDNS_UART_SR) &
 					CDNS_UART_SR_RXEMPTY))
-			readl(port->membase + CDNS_UART_FIFO_OFFSET);
+			readl(port->membase + CDNS_UART_FIFO);
 		/* set RX trigger level to 1 */
-		writel(1, port->membase + CDNS_UART_RXWM_OFFSET);
+		writel(1, port->membase + CDNS_UART_RXWM);
 		/* disable RX timeout interrups */
-		writel(CDNS_UART_IXR_TOUT,
-				port->membase + CDNS_UART_IDR_OFFSET);
+		writel(CDNS_UART_IXR_TOUT, port->membase + CDNS_UART_IDR);
 		spin_unlock_irqrestore(&port->lock, flags);
 	}
 
@@ -1300,30 +1293,28 @@ static int cdns_uart_resume(struct device *device)
 		spin_lock_irqsave(&port->lock, flags);
 
 		/* Set TX/RX Reset */
-		ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+		ctrl_reg = readl(port->membase + CDNS_UART_CR);
 		ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
-		writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
-		while (readl(port->membase + CDNS_UART_CR_OFFSET) &
+		writel(ctrl_reg, port->membase + CDNS_UART_CR);
+		while (readl(port->membase + CDNS_UART_CR) &
 				(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST))
 			cpu_relax();
 
 		/* restore rx timeout value */
-		writel(rx_timeout, port->membase + CDNS_UART_RXTOUT_OFFSET);
+		writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);
 		/* Enable Tx/Rx */
-		ctrl_reg = readl(port->membase + CDNS_UART_CR_OFFSET);
+		ctrl_reg = readl(port->membase + CDNS_UART_CR);
 		ctrl_reg &= ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS);
 		ctrl_reg |= CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN;
-		writel(ctrl_reg, port->membase + CDNS_UART_CR_OFFSET);
+		writel(ctrl_reg, port->membase + CDNS_UART_CR);
 
 		spin_unlock_irqrestore(&port->lock, flags);
 	} else {
 		spin_lock_irqsave(&port->lock, flags);
 		/* restore original rx trigger level */
-		writel(rx_trigger_level,
-				port->membase + CDNS_UART_RXWM_OFFSET);
+		writel(rx_trigger_level, port->membase + CDNS_UART_RXWM);
 		/* enable RX timeout interrupt */
-		writel(CDNS_UART_IXR_TOUT,
-				port->membase + CDNS_UART_IER_OFFSET);
+		writel(CDNS_UART_IXR_TOUT, port->membase + CDNS_UART_IER);
 		spin_unlock_irqrestore(&port->lock, flags);
 	}
 
-- 
2.7.0.3.g497ea1e

[PATCH LINUX 6/6] tty: xuartps: Consolidate TX handling

[Soren Brinkmann]

start_tx and the ISR used largely identical code to transmit data.
Consolidate that in one place.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 97 ++++++++++++++++----------------------
 1 file changed, 40 insertions(+), 57 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 3ff6e3c2347c..131a3117fbbb 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -239,6 +239,41 @@ static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
 	tty_flip_buffer_push(&port->state->port);
 }
 
+static void cdns_uart_handle_tx(struct uart_port *port)
+{
+	unsigned int numbytes;
+
+	if (uart_circ_empty(&port->state->xmit)) {
+		writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IDR);
+		return;
+	}
+
+	numbytes = port->fifosize;
+	while (numbytes && !uart_circ_empty(&port->state->xmit) &&
+	       !(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL)) {
+		/*
+		 * Get the data from the UART circular buffer
+		 * and write it to the cdns_uart's TX_FIFO
+		 * register.
+		 */
+		writel(port->state->xmit.buf[port->state->xmit.tail],
+			port->membase + CDNS_UART_FIFO);
+		port->icount.tx++;
+
+		/*
+		 * Adjust the tail of the UART buffer and wrap
+		 * the buffer if it reaches limit.
+		 */
+		port->state->xmit.tail =
+			(port->state->xmit.tail + 1) & (UART_XMIT_SIZE - 1);
+
+		numbytes--;
+	}
+
+	if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
 /**
  * cdns_uart_isr - Interrupt handler
  * @irq: Irq number
@@ -250,7 +285,7 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 {
 	struct uart_port *port = (struct uart_port *)dev_id;
 	unsigned long flags;
-	unsigned int isrstatus, numbytes;
+	unsigned int isrstatus;
 
 	spin_lock_irqsave(&port->lock, flags);
 
@@ -262,40 +297,8 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 	if (isrstatus & CDNS_UART_RX_IRQS)
 		cdns_uart_handle_rx(port, isrstatus);
 
-	/* Dispatch an appropriate handler */
-	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY) {
-		if (uart_circ_empty(&port->state->xmit)) {
-			writel(CDNS_UART_IXR_TXEMPTY,
-					port->membase + CDNS_UART_IDR);
-		} else {
-			numbytes = port->fifosize;
-			/* Break if no more data available in the UART buffer */
-			while (numbytes--) {
-				if (uart_circ_empty(&port->state->xmit))
-					break;
-				/* Get the data from the UART circular buffer
-				 * and write it to the cdns_uart's TX_FIFO
-				 * register.
-				 */
-				writel(port->state->xmit.buf[
-						port->state->xmit.tail],
-					port->membase + CDNS_UART_FIFO);
-
-				port->icount.tx++;
-
-				/* Adjust the tail of the UART buffer and wrap
-				 * the buffer if it reaches limit.
-				 */
-				port->state->xmit.tail =
-					(port->state->xmit.tail + 1) &
-						(UART_XMIT_SIZE - 1);
-			}
-
-			if (uart_circ_chars_pending(
-					&port->state->xmit) < WAKEUP_CHARS)
-				uart_write_wakeup(port);
-		}
-	}
+	if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY)
+		cdns_uart_handle_tx(port);
 
 	writel(isrstatus, port->membase + CDNS_UART_ISR);
 
@@ -502,7 +505,7 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb,
  */
 static void cdns_uart_start_tx(struct uart_port *port)
 {
-	unsigned int status, numbytes = port->fifosize;
+	unsigned int status;
 
 	if (uart_tx_stopped(port))
 		return;
@@ -519,31 +522,11 @@ static void cdns_uart_start_tx(struct uart_port *port)
 	if (uart_circ_empty(&port->state->xmit))
 		return;
 
-	while (numbytes-- && ((readl(port->membase + CDNS_UART_SR) &
-				CDNS_UART_SR_TXFULL)) != CDNS_UART_SR_TXFULL) {
-		/* Break if no more data available in the UART buffer */
-		if (uart_circ_empty(&port->state->xmit))
-			break;
-
-		/* Get the data from the UART circular buffer and
-		 * write it to the cdns_uart's TX_FIFO register.
-		 */
-		writel(port->state->xmit.buf[port->state->xmit.tail],
-				port->membase + CDNS_UART_FIFO);
-		port->icount.tx++;
+	cdns_uart_handle_tx(port);
 
-		/* Adjust the tail of the UART buffer and wrap
-		 * the buffer if it reaches limit.
-		 */
-		port->state->xmit.tail = (port->state->xmit.tail + 1) &
-					(UART_XMIT_SIZE - 1);
-	}
 	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR);
 	/* Enable the TX Empty interrupt */
 	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER);
-
-	if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(port);
 }
 
 /**
-- 
2.7.0.3.g497ea1e

Re: [PATCH LINUX 0/6] Second part of xuartps fixes

[Sören Brinkmann]

ping? Any comments?

	Thanks,
	Sören

On Mon, 2016-01-11 at 17:41:35 -0800, Soren Brinkmann wrote:
> Hi,
> 
> this is the second part of fixes for xuartps that evolved from this
> series: https://lkml.org/lkml/2015/12/26/26.
> 
> This series, obviously, depends on the patches mentioned above. It
> includes several minor improvements and refactoring and the refactoring
> of the IRQ management, which prevents lock ups that could happen when
> RX-related IRQs fired while the receiver was disabled.
> 
> 	Thanks,
> 	Sören
> 
> Sören Brinkmann (6):
>   tty: xuartps: Move request_irq to after setting up the HW
>   tty: xuartps: Refactor IRQ handling
>   tty: xuartps: Cleanup: Reformat if-else
>   tty: xuartps: Improve sysrq handling
>   tty: xuartps: Remove '_OFFSET' suffix from #defines
>   tty: xuartps: Consolidate TX handling
> 
>  drivers/tty/serial/xilinx_uartps.c | 460 +++++++++++++++++--------------------
>  1 file changed, 216 insertions(+), 244 deletions(-)
> 
> -- 
> 2.7.0.3.g497ea1e
> 

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