[PATCH 1/2 v2] imx: Add save/restore functions for UART control regs

[PATCH 1/2 v2] imx: Add save/restore functions for UART control regs

[Dirk Behme]

Factor out the uart save/restore functionality instead of
having the same code several times in the driver.

Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
CC: Saleem Abdulrasool <compnerd@compnerd.org>
CC: Sascha Hauer <s.hauer@pengutronix.de>
CC: Fabio Estevam <festevam@gmail.com>
CC: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
CC: linux-serial at vger.kernel.org
CC: Alan Cox <alan@linux.intel.com>
---
Changes in v2:
* Rename imx_console_mode/restore() to imx_port_ucrs_save/restore()
* Introduce struct imx_port_ucrs
* Add Alan Cox to CC

 drivers/tty/serial/imx.c |   43 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 163fc90..3daa008 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -207,6 +207,12 @@ struct imx_port {
 	struct imx_uart_data	*devdata;
 };
 
+struct imx_port_ucrs {
+	unsigned int	ucr1;
+	unsigned int	ucr2;
+	unsigned int	ucr3;
+};
+
 #ifdef CONFIG_IRDA
 #define USE_IRDA(sport)	((sport)->use_irda)
 #else
@@ -260,6 +266,27 @@ static inline int is_imx21_uart(struct imx_port *sport)
 }
 
 /*
+ * Save and restore functions for UCR1, UCR2 and UCR3 registers
+ */
+static void imx_port_ucrs_save(struct uart_port *port,
+			       struct imx_port_ucrs *ucr)
+{
+	/* save control registers */
+	ucr->ucr1 = readl(port->membase + UCR1);
+	ucr->ucr2 = readl(port->membase + UCR2);
+	ucr->ucr3 = readl(port->membase + UCR3);
+}
+
+static void imx_port_ucrs_restore(struct uart_port *port,
+				  struct imx_port_ucrs *ucr)
+{
+	/* restore control registers */
+	writel(ucr->ucr1, port->membase + UCR1);
+	writel(ucr->ucr2, port->membase + UCR2);
+	writel(ucr->ucr3, port->membase + UCR3);
+}
+
+/*
  * Handle any change of modem status signal since we were last called.
  */
 static void imx_mctrl_check(struct imx_port *sport)
@@ -1118,13 +1145,14 @@ static void
 imx_console_write(struct console *co, const char *s, unsigned int count)
 {
 	struct imx_port *sport = imx_ports[co->index];
-	unsigned int old_ucr1, old_ucr2, ucr1;
+	struct imx_port_ucrs old_ucr;
+	unsigned int ucr1;
 
 	/*
-	 *	First, save UCR1/2 and then disable interrupts
+	 *	First, save UCR1/2/3 and then disable interrupts
 	 */
-	ucr1 = old_ucr1 = readl(sport->port.membase + UCR1);
-	old_ucr2 = readl(sport->port.membase + UCR2);
+	imx_port_ucrs_save(&sport->port, &old_ucr);
+	ucr1 = old_ucr.ucr1;
 
 	if (is_imx1_uart(sport))
 		ucr1 |= IMX1_UCR1_UARTCLKEN;
@@ -1133,18 +1161,17 @@ imx_console_write(struct console *co, const char *s, unsigned int count)
 
 	writel(ucr1, sport->port.membase + UCR1);
 
-	writel(old_ucr2 | UCR2_TXEN, sport->port.membase + UCR2);
+	writel(old_ucr.ucr2 | UCR2_TXEN, sport->port.membase + UCR2);
 
 	uart_console_write(&sport->port, s, count, imx_console_putchar);
 
 	/*
 	 *	Finally, wait for transmitter to become empty
-	 *	and restore UCR1/2
+	 *	and restore UCR1/2/3
 	 */
 	while (!(readl(sport->port.membase + USR2) & USR2_TXDC));
 
-	writel(old_ucr1, sport->port.membase + UCR1);
-	writel(old_ucr2, sport->port.membase + UCR2);
+	imx_port_ucrs_restore(&sport->port, &old_ucr);
 }
 
 /*
-- 
1.7.7.4

[PATCH 2/2 v3] imx: add polled io uart methods

[Dirk Behme]

From: Saleem Abdulrasool <compnerd@compnerd.org>

These methods are invoked if the iMX uart is used in conjuction with kgdb during
early boot.  In order to access the UART without the interrupts, the kernel uses
the basic polling methods for IO with the device.  With these methods
implemented, it is now possible to enable kgdb during early boot over serial.

Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
CC: Sascha Hauer <s.hauer@pengutronix.de>
CC: Fabio Estevam <festevam@gmail.com>
CC: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
CC: linux-serial at vger.kernel.org
CC: Alan Cox <alan@linux.intel.com>
---
Changes in v3:
* Remove blank line
* Remove '& 0xff' in 'return c' as 'c' is an unsigned char
* Rename imx_console_mode/restore() to imx_port_ucrs_save/restore()
* Add Alan Cox to CC

Changes in the v2 compared to Saleem's original version:
* Remove volatile form status variable
* Remove blank line
* Factor out imx_console_mode/restore()

 drivers/tty/serial/imx.c |   69 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 69 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 3daa008..d6162ec 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -102,6 +102,7 @@
 #define  UCR2_STPB       (1<<6)	 /* Stop */
 #define  UCR2_WS         (1<<5)	 /* Word size */
 #define  UCR2_RTSEN      (1<<4)	 /* Request to send interrupt enable */
+#define  UCR2_ATEN       (1<<3)  /* Aging Timer Enable */
 #define  UCR2_TXEN       (1<<2)	 /* Transmitter enabled */
 #define  UCR2_RXEN       (1<<1)	 /* Receiver enabled */
 #define  UCR2_SRST 	 (1<<0)	 /* SW reset */
@@ -1106,6 +1107,70 @@ imx_verify_port(struct uart_port *port, struct serial_struct *ser)
 	return ret;
 }
 
+#if defined(CONFIG_CONSOLE_POLL)
+static int imx_poll_get_char(struct uart_port *port)
+{
+	struct imx_port_ucrs old_ucr;
+	unsigned int status;
+	unsigned char c;
+
+	/* save control registers */
+	imx_port_ucrs_save(port, &old_ucr);
+
+	/* disable interrupts */
+	writel(UCR1_UARTEN, port->membase + UCR1);
+	writel(old_ucr.ucr2 & ~(UCR2_ATEN | UCR2_RTSEN | UCR2_ESCI),
+	       port->membase + UCR2);
+	writel(old_ucr.ucr3 & ~(UCR3_DCD | UCR3_RI | UCR3_DTREN),
+	       port->membase + UCR3);
+
+	/* poll */
+	do {
+		status = readl(port->membase + USR2);
+	} while (~status & USR2_RDR);
+
+	/* read */
+	c = readl(port->membase + URXD0);
+
+	/* restore control registers */
+	imx_port_ucrs_restore(port, &old_ucr);
+
+	return c;
+}
+
+static void imx_poll_put_char(struct uart_port *port, unsigned char c)
+{
+	struct imx_port_ucrs old_ucr;
+	unsigned int status;
+
+	/* save control registers */
+	imx_port_ucrs_save(port, &old_ucr);
+
+	/* disable interrupts */
+	writel(UCR1_UARTEN, port->membase + UCR1);
+	writel(old_ucr.ucr2 & ~(UCR2_ATEN | UCR2_RTSEN | UCR2_ESCI),
+	       port->membase + UCR2);
+	writel(old_ucr.ucr3 & ~(UCR3_DCD | UCR3_RI | UCR3_DTREN),
+	       port->membase + UCR3);
+
+	/* drain */
+	do {
+		status = readl(port->membase + USR1);
+	} while (~status & USR1_TRDY);
+
+	/* write */
+	writel(c, port->membase + URTX0);
+
+	/* flush */
+	do {
+		status = readl(port->membase + USR2);
+	} while (~status & USR2_TXDC);
+
+	/* restore control registers */
+	imx_port_ucrs_restore(port, &old_ucr);
+}
+#endif
+
 static struct uart_ops imx_pops = {
 	.tx_empty	= imx_tx_empty,
 	.set_mctrl	= imx_set_mctrl,
@@ -1123,6 +1188,10 @@ static struct uart_ops imx_pops = {
 	.request_port	= imx_request_port,
 	.config_port	= imx_config_port,
 	.verify_port	= imx_verify_port,
+#if defined(CONFIG_CONSOLE_POLL)
+	.poll_get_char  = imx_poll_get_char,
+	.poll_put_char  = imx_poll_put_char,
+#endif
 };
 
 static struct imx_port *imx_ports[UART_NR];
-- 
1.7.7.4

[PATCH 1/2 v2] imx: Add save/restore functions for UART control regs

[Shawn Guo]

On Thu, Dec 22, 2011 at 09:57:52AM +0100, Dirk Behme wrote:
> Factor out the uart save/restore functionality instead of
> having the same code several times in the driver.
> 
> Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
> CC: Saleem Abdulrasool <compnerd@compnerd.org>
> CC: Sascha Hauer <s.hauer@pengutronix.de>
> CC: Fabio Estevam <festevam@gmail.com>
> CC: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
> CC: linux-serial at vger.kernel.org
> CC: Alan Cox <alan@linux.intel.com>

I queued this for 3.3, and will send a pull-request to Greg.

-- 
Regards,
Shawn

[PATCH 2/2 v3] imx: add polled io uart methods

[Shawn Guo]

On Thu, Dec 22, 2011 at 09:57:53AM +0100, Dirk Behme wrote:
> From: Saleem Abdulrasool <compnerd@compnerd.org>
> 
> These methods are invoked if the iMX uart is used in conjuction with kgdb during
> early boot.  In order to access the UART without the interrupts, the kernel uses
> the basic polling methods for IO with the device.  With these methods
> implemented, it is now possible to enable kgdb during early boot over serial.
> 
> Signed-off-by: Saleem Abdulrasool <compnerd@compnerd.org>
> Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
> CC: Sascha Hauer <s.hauer@pengutronix.de>
> CC: Fabio Estevam <festevam@gmail.com>
> CC: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
> CC: linux-serial at vger.kernel.org
> CC: Alan Cox <alan@linux.intel.com>

I queued this for 3.3, and will send a pull-request to Greg.

-- 
Regards,
Shawn