[PATCH] Add poll_get_char and poll_put_char uart_ops to atmel_serial.

[Albin Tonnerre-3]

[Please CC: me on replies, I'm not subscribed]

This patch allows using KGDB over the console with the atmel_serial
driver.

Signed-off-by: Albin Tonnerre <albin.tonnerre@...>
---
 drivers/serial/atmel_serial.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index b3497d7..aaab321 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -1211,6 +1211,29 @@ static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
  return ret;
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+static int atmel_poll_get_char(struct uart_port *port)
+{
+ struct atmel_uart_port *aup = to_atmel_uart_port(port);
+
+ while (!(readb(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_RXRDY))
+ barrier();
+
+ return readb(aup->uart.membase + ATMEL_US_RHR);
+}
+
+static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
+{
+ struct atmel_uart_port *aup = to_atmel_uart_port(port);
+ unsigned int status;
+
+ while (!(readb(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_TXRDY))
+ barrier();
+
+ writeb(ch, aup->uart.membase + ATMEL_US_THR);
+}
+#endif
+
 static struct uart_ops atmel_pops = {
  .tx_empty = atmel_tx_empty,
  .set_mctrl = atmel_set_mctrl,
@@ -1230,6 +1253,10 @@ static struct uart_ops atmel_pops = {
  .config_port = atmel_config_port,
  .verify_port = atmel_verify_port,
  .pm = atmel_serial_pm,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_get_char = atmel_poll_get_char,
+ .poll_put_char = atmel_poll_put_char,
+#endif
 };
 
 /*
--
1.6.0.4

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[Haavard Skinnemoen-4]

[added AT91 maintainers to Cc]

Albin Tonnerre wrote:

> +#ifdef CONFIG_CONSOLE_POLL
> +static int atmel_poll_get_char(struct uart_port *port)
> +{
> + struct atmel_uart_port *aup = to_atmel_uart_port(port);
> +
> + while (!(readb(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_RXRDY))
> + barrier();
> +
> + return readb(aup->uart.membase + ATMEL_US_RHR);
> +}
> +
> +static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
> +{
> + struct atmel_uart_port *aup = to_atmel_uart_port(port);
> + unsigned int status;
> +
> + while (!(readb(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_TXRDY))
> + barrier();
> +
> + writeb(ch, aup->uart.membase + ATMEL_US_THR);
> +}
> +#endif

All the registers are 32 bits wide, so you should use __raw_readl() and
__raw_writel() to avoid any endianness issues (AT91 is little endian
and AVR32 is big endian).

Haavard
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[Albin Tonnerre-4]

This patch allows using KGDB over the console with the atmel_serial
driver.

Signed-off-by: Albin Tonnerre <albin.tonnerre@...>
---
 Updated patch to use __raw_readl/__raw_writel, as per Haavard's comments.

 drivers/serial/atmel_serial.c |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 338b15c..1e65046 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -1213,6 +1213,28 @@ static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
  return ret;
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+static int atmel_poll_get_char(struct uart_port *port)
+{
+ struct atmel_uart_port *aup = to_atmel_uart_port(port);
+
+ while (!(__raw_readl(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_RXRDY))
+ barrier();
+
+ return __raw_readl(aup->uart.membase + ATMEL_US_RHR);
+}
+
+static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
+{
+ struct atmel_uart_port *aup = to_atmel_uart_port(port);
+
+ while (!(__raw_readl(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_TXRDY))
+ barrier();
+
+ __raw_writel(ch, aup->uart.membase + ATMEL_US_THR);
+}
+#endif
+
 static struct uart_ops atmel_pops = {
  .tx_empty = atmel_tx_empty,
  .set_mctrl = atmel_set_mctrl,
@@ -1232,6 +1254,10 @@ static struct uart_ops atmel_pops = {
  .config_port = atmel_config_port,
  .verify_port = atmel_verify_port,
  .pm = atmel_serial_pm,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_get_char = atmel_poll_get_char,
+ .poll_put_char = atmel_poll_put_char,
+#endif
 };
 
 /*
--
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
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[Haavard Skinnemoen-4]

Albin Tonnerre wrote:
> This patch allows using KGDB over the console with the atmel_serial
> driver.
>
> Signed-off-by: Albin Tonnerre <albin.tonnerre@...>

Acked-by: Haavard Skinnemoen <haavard.skinnemoen@...>
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[Albin Tonnerre-4]

On Tue, Jul 28, 2009 at 06:09:41PM +0200, Haavard Skinnemoen wrote :
> Albin Tonnerre wrote:
> > This patch allows using KGDB over the console with the atmel_serial
> > driver.
> >
> > Signed-off-by: Albin Tonnerre <albin.tonnerre@...>
>
> Acked-by: Haavard Skinnemoen <haavard.skinnemoen@...>

Nicolas, Andrew: Any news on this?

Regards,
--
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
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[Andrew Victor-3]

hi Albin,

Any reason you're not using the register access macro's like the rest
of the driver?

> +       while (!(__raw_readl(aup->uart.membase + ATMEL_US_CSR) & ATMEL_US_RXRDY))

while (!(UART_GET_CSR(..) & ATMEL_US_RXRDY))

> +       return __raw_readl(aup->uart.membase + ATMEL_US_RHR);

return UART_GET_CHAR(..);

> +       __raw_writel(ch, aup->uart.membase + ATMEL_US_THR);

UART_PUT_CHAR(..., ch);


Otherwise the patch looks fine to me.

Regards,
  Andrew Victor
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[Albin Tonnerre-4]

This patch allows using KGDB over the console with the atmel_serial
driver.

Signed-off-by: Albin Tonnerre <albin.tonnerre@...>
---
changes: Use register access macros instead of __raw_readl/writel

 drivers/serial/atmel_serial.c |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 607d43a..c562883 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -1213,6 +1213,24 @@ static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
  return ret;
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+static int atmel_poll_get_char(struct uart_port *port)
+{
+ while (!(UART_GET_CSR(port) & ATMEL_US_RXRDY))
+ barrier();
+
+ return UART_GET_CHAR(port);
+}
+
+static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
+{
+ while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY))
+ barrier();
+
+ UART_PUT_CHAR(port, ch);
+}
+#endif
+
 static struct uart_ops atmel_pops = {
  .tx_empty = atmel_tx_empty,
  .set_mctrl = atmel_set_mctrl,
@@ -1232,6 +1250,10 @@ static struct uart_ops atmel_pops = {
  .config_port = atmel_config_port,
  .verify_port = atmel_verify_port,
  .pm = atmel_serial_pm,
+#ifdef CONFIG_CONSOLE_POLL
+ .poll_get_char = atmel_poll_get_char,
+ .poll_put_char = atmel_poll_put_char,
+#endif
 };
 
 /*
--
1.6.3.3

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[Andrew Victor-3]

hi Albin,

> This patch allows using KGDB over the console with the atmel_serial
> driver.
>
> Signed-off-by: Albin Tonnerre <albin.tonnerre@...>

Acked-by: Andrew Victor <linux@...>
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[Haavard Skinnemoen-4]

Albin Tonnerre <albin.tonnerre@...> wrote:
> This patch allows using KGDB over the console with the atmel_serial
> driver.
>
> Signed-off-by: Albin Tonnerre <albin.tonnerre@...>

Acked-by: Haavard Skinnemoen <haavard.skinnemoen@...>
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[Albin Tonnerre-4]

On Tue, 08 Sep 2009 10:30 +0200, Haavard Skinnemoen wrote :
> Albin Tonnerre <albin.tonnerre@...> wrote:
> > This patch allows using KGDB over the console with the atmel_serial
> > driver.
> >
> > Signed-off-by: Albin Tonnerre <albin.tonnerre@...>
>
> Acked-by: Haavard Skinnemoen <haavard.skinnemoen@...>

Thanks Haavard & Andrew for your Acked-by. Is there anything I need to do to get
this pushed to mainline?

Regards,
--
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
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[Albin Tonnerre-4]

On Fri, 11 Sep 2009 13:31 +0200, Albin Tonnerre wrote :
> On Tue, 08 Sep 2009 10:30 +0200, Haavard Skinnemoen wrote :
> > Albin Tonnerre <albin.tonnerre@...> wrote:
> > > This patch allows using KGDB over the console with the atmel_serial
> > > driver.

> > > Signed-off-by: Albin Tonnerre <albin.tonnerre@...>

> > Acked-by: Haavard Skinnemoen <haavard.skinnemoen@...>

> Thanks Haavard & Andrew for your Acked-by. Is there anything I need to do to get
> this pushed to mainline?

Ping?

Cheers,
--
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
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[Albin Tonnerre-4]

Andrew, could you please pick this up ? It got:

Acked-by: Haavard Skinnemoen <haavard.skinnemoen@...>
Acked-by: Andrew Victor <linux@...>

Regards,
Albin

On Mon, 07 Sep 2009 11:52 +0200, Albin Tonnerre wrote :

> This patch allows using KGDB over the console with the atmel_serial
> driver.
>
> Signed-off-by: Albin Tonnerre <albin.tonnerre@...>
> ---
> changes: Use register access macros instead of __raw_readl/writel
>
>  drivers/serial/atmel_serial.c |   22 ++++++++++++++++++++++
>  1 files changed, 22 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
> index 607d43a..c562883 100644
> --- a/drivers/serial/atmel_serial.c
> +++ b/drivers/serial/atmel_serial.c
> @@ -1213,6 +1213,24 @@ static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
>   return ret;
>  }
>  
> +#ifdef CONFIG_CONSOLE_POLL
> +static int atmel_poll_get_char(struct uart_port *port)
> +{
> + while (!(UART_GET_CSR(port) & ATMEL_US_RXRDY))
> + barrier();
> +
> + return UART_GET_CHAR(port);
> +}
> +
> +static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
> +{
> + while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY))
> + barrier();
> +
> + UART_PUT_CHAR(port, ch);
> +}
> +#endif
> +
>  static struct uart_ops atmel_pops = {
>   .tx_empty = atmel_tx_empty,
>   .set_mctrl = atmel_set_mctrl,
> @@ -1232,6 +1250,10 @@ static struct uart_ops atmel_pops = {
>   .config_port = atmel_config_port,
>   .verify_port = atmel_verify_port,
>   .pm = atmel_serial_pm,
> +#ifdef CONFIG_CONSOLE_POLL
> + .poll_get_char = atmel_poll_get_char,
> + .poll_put_char = atmel_poll_put_char,
> +#endif
>  };
>  
>  /*

--
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
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[Andrew Morton-9]

On Mon,  7 Sep 2009 11:52:50 +0200
Albin Tonnerre <albin.tonnerre@...> wrote:

> +#ifdef CONFIG_CONSOLE_POLL
> +static int atmel_poll_get_char(struct uart_port *port)
> +{
> + while (!(UART_GET_CSR(port) & ATMEL_US_RXRDY))
> + barrier();
> +
> + return UART_GET_CHAR(port);
> +}
> +
> +static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
> +{
> + while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY))
> + barrier();
> +
> + UART_PUT_CHAR(port, ch);
> +}
> +#endif

The use of barrier() is not appropriate here - it's purely a compiler
concept.

I'll switch it to cpu_relax().  Even that's probably unneeded, as the
IO operation is usually slow and should be an opportunity for the CPU
to take a little nap.

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