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From: Soren Brinkmann <soren.brinkmann@xilinx.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>
Cc: Michal Simek <michal.simek@xilinx.com>,
	<linux-serial@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	"Soren Brinkmann" <soren.brinkmann@xilinx.com>
Subject: [PATCH 2/9] tty: xuartps: Use spinlock to serialize HW access
Date: Tue, 3 Nov 2015 16:20:43 -0800	[thread overview]
Message-ID: <1446596450-20918-3-git-send-email-soren.brinkmann@xilinx.com> (raw)
In-Reply-To: <1446596450-20918-1-git-send-email-soren.brinkmann@xilinx.com>

Instead of disabling the IRQ, use the spin lock to serialize accesses to
the HW. This protects the driver from interference of non-IRQ callbacks
with each other and makes the driver more consistent in its
serialization method.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 50d4082d2354..dc1987f3dc0a 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -947,10 +947,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 {
 	u32 imr;
 	int c;
+	unsigned long flags;
 
-	/* Disable all interrupts */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Check if FIFO is empty */
 	if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
@@ -959,8 +958,7 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 		c = (unsigned char) readl(
 					port->membase + CDNS_UART_FIFO_OFFSET);
 
-	/* Enable interrupts */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return c;
 }
@@ -968,10 +966,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 {
 	u32 imr;
+	unsigned long flags;
 
-	/* Disable all interrupts */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Wait until FIFO is empty */
 	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
@@ -986,8 +983,7 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 				CDNS_UART_SR_TXEMPTY))
 		cpu_relax();
 
-	/* Enable interrupts */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return;
 }
-- 
2.6.2.3.ga463a5b


WARNING: multiple messages have this Message-ID (diff)
From: Soren Brinkmann <soren.brinkmann@xilinx.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>
Cc: linux-arm-kernel@lists.infradead.org,
	Soren Brinkmann <soren.brinkmann@xilinx.com>,
	Michal Simek <michal.simek@xilinx.com>,
	linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/9] tty: xuartps: Use spinlock to serialize HW access
Date: Tue, 3 Nov 2015 16:20:43 -0800	[thread overview]
Message-ID: <1446596450-20918-3-git-send-email-soren.brinkmann@xilinx.com> (raw)
In-Reply-To: <1446596450-20918-1-git-send-email-soren.brinkmann@xilinx.com>

Instead of disabling the IRQ, use the spin lock to serialize accesses to
the HW. This protects the driver from interference of non-IRQ callbacks
with each other and makes the driver more consistent in its
serialization method.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 50d4082d2354..dc1987f3dc0a 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -947,10 +947,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 {
 	u32 imr;
 	int c;
+	unsigned long flags;
 
-	/* Disable all interrupts */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Check if FIFO is empty */
 	if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
@@ -959,8 +958,7 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 		c = (unsigned char) readl(
 					port->membase + CDNS_UART_FIFO_OFFSET);
 
-	/* Enable interrupts */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return c;
 }
@@ -968,10 +966,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 {
 	u32 imr;
+	unsigned long flags;
 
-	/* Disable all interrupts */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Wait until FIFO is empty */
 	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
@@ -986,8 +983,7 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 				CDNS_UART_SR_TXEMPTY))
 		cpu_relax();
 
-	/* Enable interrupts */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return;
 }
-- 
2.6.2.3.ga463a5b

WARNING: multiple messages have this Message-ID (diff)
From: soren.brinkmann@xilinx.com (Soren Brinkmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/9] tty: xuartps: Use spinlock to serialize HW access
Date: Tue, 3 Nov 2015 16:20:43 -0800	[thread overview]
Message-ID: <1446596450-20918-3-git-send-email-soren.brinkmann@xilinx.com> (raw)
In-Reply-To: <1446596450-20918-1-git-send-email-soren.brinkmann@xilinx.com>

Instead of disabling the IRQ, use the spin lock to serialize accesses to
the HW. This protects the driver from interference of non-IRQ callbacks
with each other and makes the driver more consistent in its
serialization method.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 50d4082d2354..dc1987f3dc0a 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -947,10 +947,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 {
 	u32 imr;
 	int c;
+	unsigned long flags;
 
-	/* Disable all interrupts */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Check if FIFO is empty */
 	if (readl(port->membase + CDNS_UART_SR_OFFSET) & CDNS_UART_SR_RXEMPTY)
@@ -959,8 +958,7 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 		c = (unsigned char) readl(
 					port->membase + CDNS_UART_FIFO_OFFSET);
 
-	/* Enable interrupts */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return c;
 }
@@ -968,10 +966,9 @@ static int cdns_uart_poll_get_char(struct uart_port *port)
 static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 {
 	u32 imr;
+	unsigned long flags;
 
-	/* Disable all interrupts */
-	imr = readl(port->membase + CDNS_UART_IMR_OFFSET);
-	writel(imr, port->membase + CDNS_UART_IDR_OFFSET);
+	spin_lock_irqsave(&port->lock, flags);
 
 	/* Wait until FIFO is empty */
 	while (!(readl(port->membase + CDNS_UART_SR_OFFSET) &
@@ -986,8 +983,7 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 				CDNS_UART_SR_TXEMPTY))
 		cpu_relax();
 
-	/* Enable interrupts */
-	writel(imr, port->membase + CDNS_UART_IER_OFFSET);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	return;
 }
-- 
2.6.2.3.ga463a5b

  parent reply	other threads:[~2015-11-04  0:23 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-04  0:20 [PATCH 0/9] tty: xuartps: Fix lock ups Soren Brinkmann
2015-11-04  0:20 ` Soren Brinkmann
2015-11-04  0:20 ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 1/9] tty: xuartps: Beautify read-modify writes Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` Soren Brinkmann [this message]
2015-11-04  0:20   ` [PATCH 2/9] tty: xuartps: Use spinlock to serialize HW access Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:52   ` kbuild test robot
2015-11-04  0:52     ` kbuild test robot
2015-11-04  0:52     ` kbuild test robot
2015-11-04  0:20 ` [PATCH 3/9] tty: xuartps: Always enable transmitter in start_tx Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 4/9] tty: xuartps: Clear interrupt status register in shutdown Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 5/9] tty: xuartps: Improve startup function Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 6/9] tty: xuartps: Keep lock for whole ISR Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 7/9] tty: xuartps: Acquire port lock for shutdown Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 8/9] tty: xuartps: Move RX path into helper function Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20 ` [PATCH 9/9] tty: xuartps: Only handle RX IRQs when RX is enabled Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann
2015-11-04  0:20   ` Soren Brinkmann

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