[PATCH v2] serial: meson: add Magic SysRq support

Subsystems: the rest, tty layer and serial drivers

STALE3243d

4 messages, 2 authors, 2017-10-20 · open the first message on its own page

[PATCH v2] serial: meson: add Magic SysRq support

From: Yixun Lan <hidden>
Date: 2017-09-06 13:53:20 

This dirver try to implement the Magic SysRq support[1] for
Amlogic Inc's meson platfo
From the hardware perspective, the UART IP can't detect the 'BREAK' command
clearly via the status register. Instead, we rely on the combination of
'FRAME_ERR bit && ch == 0', and it works fine.

[1] Documentation/admin-guide/sysrq.rst

Signed-off-by: Yixun Lan <redacted>

---
Changes since v1 at [0]:
- add changelog & a few more comments

[0] https://patchwork.kernel.org/patch/9728475/
---
 drivers/tty/serial/meson_uart.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 42e4a4c7597f..3fea24bafd80 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -14,6 +14,10 @@
  *
  */
 
+#if defined(CONFIG_SERIAL_MESON_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
@@ -183,12 +187,12 @@ static void meson_receive_chars(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
 	char flag;
-	u32 status, ch, mode;
+	u32 ostatus, status, ch, mode;
 
 	do {
 		flag = TTY_NORMAL;
 		port->icount.rx++;
-		status = readl(port->membase + AML_UART_STATUS);
+		ostatus = status = readl(port->membase + AML_UART_STATUS);
 
 		if (status & AML_UART_ERR) {
 			if (status & AML_UART_TX_FIFO_WERR)
@@ -216,6 +220,16 @@ static void meson_receive_chars(struct uart_port *port)
 		ch = readl(port->membase + AML_UART_RFIFO);
 		ch &= 0xff;
 
+		if ((ostatus & AML_UART_FRAME_ERR) && (ch == 0)) {
+			port->icount.brk++;
+			flag = TTY_BREAK;
+			if (uart_handle_break(port))
+				continue;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+
 		if ((status & port->ignore_status_mask) == 0)
 			tty_insert_flip_char(tport, ch, flag);
 
-- 
2.14.1

Re: [PATCH v2] serial: meson: add Magic SysRq support

From: Neil Armstrong <hidden>
Date: 2017-10-20 08:10:49 

Hi Yixun,

On 06/09/2017 15:52, Yixun Lan wrote:
This dirver try to implement the Magic SysRq support[1] for
Amlogic Inc's meson platfo
Please fix these typos.
quoted hunk
From the hardware perspective, the UART IP can't detect the 'BREAK' command
clearly via the status register. Instead, we rely on the combination of
'FRAME_ERR bit && ch == 0', and it works fine.

[1] Documentation/admin-guide/sysrq.rst

Signed-off-by: Yixun Lan <redacted>

---
Changes since v1 at [0]:
- add changelog & a few more comments

[0] https://patchwork.kernel.org/patch/9728475/
---
 drivers/tty/serial/meson_uart.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 42e4a4c7597f..3fea24bafd80 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -14,6 +14,10 @@
  *
  */
 
+#if defined(CONFIG_SERIAL_MESON_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
@@ -183,12 +187,12 @@ static void meson_receive_chars(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
 	char flag;
-	u32 status, ch, mode;
+	u32 ostatus, status, ch, mode;
 
 	do {
 		flag = TTY_NORMAL;
 		port->icount.rx++;
-		status = readl(port->membase + AML_UART_STATUS);
+		ostatus = status = readl(port->membase + AML_UART_STATUS);
 
 		if (status & AML_UART_ERR) {
 			if (status & AML_UART_TX_FIFO_WERR)
@@ -216,6 +220,16 @@ static void meson_receive_chars(struct uart_port *port)
 		ch = readl(port->membase + AML_UART_RFIFO);
 		ch &= 0xff;
 
+		if ((ostatus & AML_UART_FRAME_ERR) && (ch == 0)) {
+			port->icount.brk++;
+			flag = TTY_BREAK;
+			if (uart_handle_break(port))
+				continue;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+
 		if ((status & port->ignore_status_mask) == 0)
 			tty_insert_flip_char(tport, ch, flag);
 
Reviewed-by: Neil Armstrong <redacted>

Re: [PATCH v2] serial: meson: add Magic SysRq support

From: Yixun Lan <hidden>
Date: 2017-10-20 08:32:44 

Hi Greg-KH

I think you've already accepted this patch (and merged into your git repo)

so, is it possible for you to amend the commit message? or do you want me
to send a PATCH v3 then?


On 10:10 Fri 20 Oct     , Neil Armstrong wrote:
Hi Yixun,

On 06/09/2017 15:52, Yixun Lan wrote:
quoted
This dirver try to implement the Magic SysRq support[1] for
Amlogic Inc's meson platfo
Please fix these typos.
oops, not sure why this line is broken..

s/platfo/platform./
and should squash next line .
quoted
From the hardware perspective, the UART IP can't detect the 'BREAK' command
clearly via the status register. Instead, we rely on the combination of
'FRAME_ERR bit && ch == 0', and it works fine.

[1] Documentation/admin-guide/sysrq.rst

Signed-off-by: Yixun Lan <redacted>

---
Changes since v1 at [0]:
- add changelog & a few more comments

[0] https://patchwork.kernel.org/patch/9728475/
---
 drivers/tty/serial/meson_uart.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 42e4a4c7597f..3fea24bafd80 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -14,6 +14,10 @@
  *
  */
 
+#if defined(CONFIG_SERIAL_MESON_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
@@ -183,12 +187,12 @@ static void meson_receive_chars(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
 	char flag;
-	u32 status, ch, mode;
+	u32 ostatus, status, ch, mode;
 
 	do {
 		flag = TTY_NORMAL;
 		port->icount.rx++;
-		status = readl(port->membase + AML_UART_STATUS);
+		ostatus = status = readl(port->membase + AML_UART_STATUS);
 
 		if (status & AML_UART_ERR) {
 			if (status & AML_UART_TX_FIFO_WERR)
@@ -216,6 +220,16 @@ static void meson_receive_chars(struct uart_port *port)
 		ch = readl(port->membase + AML_UART_RFIFO);
 		ch &= 0xff;
 
+		if ((ostatus & AML_UART_FRAME_ERR) && (ch == 0)) {
+			port->icount.brk++;
+			flag = TTY_BREAK;
+			if (uart_handle_break(port))
+				continue;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+
 		if ((status & port->ignore_status_mask) == 0)
 			tty_insert_flip_char(tport, ch, flag);
 
Reviewed-by: Neil Armstrong <redacted>

_______________________________________________
linux-amlogic mailing list
linux-amlogic at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic
-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55

Re: [PATCH v2] serial: meson: add Magic SysRq support

From: Neil Armstrong <hidden>
Date: 2017-10-20 08:48:43 

I Yixun,

On 20/10/2017 10:32, Yixun Lan wrote:
Hi Greg-KH

I think you've already accepted this patch (and merged into your git repo)

so, is it possible for you to amend the commit message? or do you want me
to send a PATCH v3 then?
I was not aware greg applied it, no need to amen anything, ignore my tag.

Neil

On 10:10 Fri 20 Oct     , Neil Armstrong wrote:
quoted
Hi Yixun,

On 06/09/2017 15:52, Yixun Lan wrote:
quoted
This dirver try to implement the Magic SysRq support[1] for
Amlogic Inc's meson platfo
Please fix these typos.
oops, not sure why this line is broken..

s/platfo/platform./
and should squash next line .
quoted
quoted
From the hardware perspective, the UART IP can't detect the 'BREAK' command
clearly via the status register. Instead, we rely on the combination of
'FRAME_ERR bit && ch == 0', and it works fine.

[1] Documentation/admin-guide/sysrq.rst

Signed-off-by: Yixun Lan <redacted>

---
Changes since v1 at [0]:
- add changelog & a few more comments

[0] https://patchwork.kernel.org/patch/9728475/
---
 drivers/tty/serial/meson_uart.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index 42e4a4c7597f..3fea24bafd80 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -14,6 +14,10 @@
  *
  */
 
+#if defined(CONFIG_SERIAL_MESON_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
@@ -183,12 +187,12 @@ static void meson_receive_chars(struct uart_port *port)
 {
 	struct tty_port *tport = &port->state->port;
 	char flag;
-	u32 status, ch, mode;
+	u32 ostatus, status, ch, mode;
 
 	do {
 		flag = TTY_NORMAL;
 		port->icount.rx++;
-		status = readl(port->membase + AML_UART_STATUS);
+		ostatus = status = readl(port->membase + AML_UART_STATUS);
 
 		if (status & AML_UART_ERR) {
 			if (status & AML_UART_TX_FIFO_WERR)
@@ -216,6 +220,16 @@ static void meson_receive_chars(struct uart_port *port)
 		ch = readl(port->membase + AML_UART_RFIFO);
 		ch &= 0xff;
 
+		if ((ostatus & AML_UART_FRAME_ERR) && (ch == 0)) {
+			port->icount.brk++;
+			flag = TTY_BREAK;
+			if (uart_handle_break(port))
+				continue;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+
 		if ((status & port->ignore_status_mask) == 0)
 			tty_insert_flip_char(tport, ch, flag);
 
Reviewed-by: Neil Armstrong <redacted>

_______________________________________________
linux-amlogic mailing list
linux-amlogic at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help