serial: 8250_uniphier: add earlycon support
diff mbox

Message ID 1445503154-14340-1-git-send-email-yamada.masahiro@socionext.com
State New, archived
Headers show

Commit Message

Masahiro Yamada Oct. 22, 2015, 8:39 a.m. UTC
This reuses the code of drivers/tty/serial/8250/8250_early.c except

  - Overwrite device->port.iotype and device->port.regshift for
    UPIO_MEM32 because of_setup_earlycon() has set them for UPIO_MEM.

  - Set device->baud to zero to prevent early8250_setup() from
    initializing the divisor register because port->uartclk does not
    match the frequency expected by this hardware.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 drivers/tty/serial/8250/8250_uniphier.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

Comments

Peter Hurley Oct. 28, 2015, 3:21 p.m. UTC | #1
Hi Masahiro,

On 10/22/2015 04:39 AM, Masahiro Yamada wrote:
> This reuses the code of drivers/tty/serial/8250/8250_early.c except
> 
>   - Overwrite device->port.iotype and device->port.regshift for
>     UPIO_MEM32 because of_setup_earlycon() has set them for UPIO_MEM.
> 
>   - Set device->baud to zero to prevent early8250_setup() from
>     initializing the divisor register because port->uartclk does not
>     match the frequency expected by this hardware.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
> 
>  drivers/tty/serial/8250/8250_uniphier.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
> index 245edbb..c1075c5 100644
> --- a/drivers/tty/serial/8250/8250_uniphier.c
> +++ b/drivers/tty/serial/8250/8250_uniphier.c
> @@ -13,6 +13,7 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/console.h>
>  #include <linux/io.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> @@ -34,6 +35,29 @@ struct uniphier8250_priv {
>  	spinlock_t atomic_write_lock;
>  };
>  
> +#if IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE)

#ifdef CONFIG_SERIAL_8250_CONSOLE


Customarily, IS_ENABLED() is only used in-function with control flow
statements; eg.,

	if (IS_ENABLED() && .... )
		....

> +static int __init uniphier_early_console_setup(struct earlycon_device *device,
> +					       const char *options)
> +{
> +	if (!device->port.membase)
> +		return -ENODEV;
> +
> +	/* This hardware always expects MMIO32 register interface. */
> +	device->port.iotype = UPIO_MEM32;
> +	device->port.regshift = 2;
> +
> +	/*
> +	 * Do not touch the divisor register in early_serial8250_setup();
> +	 * we assume it has been initialized by a boot loader.
> +	 */
> +	device->baud = 0;
> +
> +	return early_serial8250_setup(device, options);
> +}
> +OF_EARLYCON_DECLARE(uniphier_uart, "socionext,uniphier-uart",
> +		    uniphier_early_console_setup);

Please change the earlycon name to just "uniphier" or "uniphier8250"; eg.,

OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
		    uniphier_early_console_setup);


My earlycon series merges OF_EARLYCON_DECLARE() => EARLYCON_DECLARE()
and "uniphier" is simpler on the command line.

Regards,
Peter Hurley

> +#endif
> +
>  /*
>   * The register map is slightly different from that of 8250.
>   * IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
>
Masahiro Yamada Oct. 29, 2015, 1:49 a.m. UTC | #2
Hi Peter,



>>
>> +#if IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE)
>
> #ifdef CONFIG_SERIAL_8250_CONSOLE

I am OK with this change because this CONFIG is boolean.


I still believe

#if IS_ENABLED(CONFIG_FOO)

is a nice shorthand for

#if defined(CONFIG_FOO) || defined(CONFIG_FOO_MODULE)

when CONFIG_FOO is tristate.





>> +static int __init uniphier_early_console_setup(struct earlycon_device *device,
>> +                                            const char *options)
>> +{
>> +     if (!device->port.membase)
>> +             return -ENODEV;
>> +
>> +     /* This hardware always expects MMIO32 register interface. */
>> +     device->port.iotype = UPIO_MEM32;
>> +     device->port.regshift = 2;
>> +
>> +     /*
>> +      * Do not touch the divisor register in early_serial8250_setup();
>> +      * we assume it has been initialized by a boot loader.
>> +      */
>> +     device->baud = 0;
>> +
>> +     return early_serial8250_setup(device, options);
>> +}
>> +OF_EARLYCON_DECLARE(uniphier_uart, "socionext,uniphier-uart",
>> +                 uniphier_early_console_setup);
>
> Please change the earlycon name to just "uniphier" or "uniphier8250"; eg.,
>
> OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
>                     uniphier_early_console_setup);
>
>
> My earlycon series merges OF_EARLYCON_DECLARE() => EARLYCON_DECLARE()
> and "uniphier" is simpler on the command line.
>

I am also OK with this change, too.

But I still see  some *_serial and *_uart are used
in EARLYCON_DECLARE.

yamada@beagle:~/workspace/linux/drivers/tty$ git grep -e
'EARLYCON_DECLARE(.*_uart'
serial/8250/8250_ingenic.c:EARLYCON_DECLARE(jz4740_uart,
ingenic_early_console_setup);
serial/8250/8250_ingenic.c:OF_EARLYCON_DECLARE(jz4740_uart,
"ingenic,jz4740-uart",
serial/8250/8250_ingenic.c:EARLYCON_DECLARE(jz4775_uart,
ingenic_early_console_setup);
serial/8250/8250_ingenic.c:OF_EARLYCON_DECLARE(jz4775_uart,
"ingenic,jz4775-uart",
serial/8250/8250_ingenic.c:EARLYCON_DECLARE(jz4780_uart,
ingenic_early_console_setup);
serial/8250/8250_ingenic.c:OF_EARLYCON_DECLARE(jz4780_uart,
"ingenic,jz4780-uart",
serial/arc_uart.c:EARLYCON_DECLARE(arc_uart, arc_early_console_setup);
serial/arc_uart.c:OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart",
arc_early_console_setup);
serial/bcm63xx_uart.c:OF_EARLYCON_DECLARE(bcm63xx_uart,
"brcm,bcm6345-uart", bcm_early_console_setup);
yamada@beagle:~/workspace/linux/drivers/tty$ git grep -e
'EARLYCON_DECLARE(.*_serial'
serial/8250/8250_early.c:EARLYCON_DECLARE(uart8250, early_serial8250_setup);
serial/8250/8250_early.c:EARLYCON_DECLARE(uart, early_serial8250_setup);
serial/msm_serial.c:EARLYCON_DECLARE(msm_serial,
msm_serial_early_console_setup);
serial/msm_serial.c:OF_EARLYCON_DECLARE(msm_serial, "qcom,msm-uart",
serial/msm_serial.c:EARLYCON_DECLARE(msm_serial_dm,
msm_serial_early_console_setup_dm);
serial/msm_serial.c:OF_EARLYCON_DECLARE(msm_serial_dm, "qcom,msm-uartdm",
serial/sprd_serial.c:EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
serial/sprd_serial.c:OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
Peter Hurley Nov. 5, 2015, 4:48 p.m. UTC | #3
Hi Masahiro,

Apologies for the delay in reply; I didn't see the lower part of your email.


On 10/28/2015 09:49 PM, Masahiro Yamada wrote:
>>> +#if IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE)
>>
>> #ifdef CONFIG_SERIAL_8250_CONSOLE
> 
> I am OK with this change because this CONFIG is boolean.
> 
> 
> I still believe
> 
> #if IS_ENABLED(CONFIG_FOO)
> 
> is a nice shorthand for
> 
> #if defined(CONFIG_FOO) || defined(CONFIG_FOO_MODULE)
> 
> when CONFIG_FOO is tristate.

I agree.


>>> +static int __init uniphier_early_console_setup(struct earlycon_device *device,
>>> +                                            const char *options)
>>> +{
>>> +     if (!device->port.membase)
>>> +             return -ENODEV;
>>> +
>>> +     /* This hardware always expects MMIO32 register interface. */
>>> +     device->port.iotype = UPIO_MEM32;
>>> +     device->port.regshift = 2;
>>> +
>>> +     /*
>>> +      * Do not touch the divisor register in early_serial8250_setup();
>>> +      * we assume it has been initialized by a boot loader.
>>> +      */
>>> +     device->baud = 0;
>>> +
>>> +     return early_serial8250_setup(device, options);
>>> +}
>>> +OF_EARLYCON_DECLARE(uniphier_uart, "socionext,uniphier-uart",
>>> +                 uniphier_early_console_setup);
>>
>> Please change the earlycon name to just "uniphier" or "uniphier8250"; eg.,
>>
>> OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
>>                     uniphier_early_console_setup);
>>
>>
>> My earlycon series merges OF_EARLYCON_DECLARE() => EARLYCON_DECLARE()
>> and "uniphier" is simpler on the command line.
>>
> 
> I am also OK with this change, too.
> 
> But I still see  some *_serial and *_uart are used
> in EARLYCON_DECLARE.
> 
> yamada@beagle:~/workspace/linux/drivers/tty$ git grep -e
> 'EARLYCON_DECLARE(.*_uart'
> serial/8250/8250_ingenic.c:EARLYCON_DECLARE(jz4740_uart,
> ingenic_early_console_setup);
> serial/8250/8250_ingenic.c:OF_EARLYCON_DECLARE(jz4740_uart,
> "ingenic,jz4740-uart",
> serial/8250/8250_ingenic.c:EARLYCON_DECLARE(jz4775_uart,
> ingenic_early_console_setup);
> serial/8250/8250_ingenic.c:OF_EARLYCON_DECLARE(jz4775_uart,
> "ingenic,jz4775-uart",
> serial/8250/8250_ingenic.c:EARLYCON_DECLARE(jz4780_uart,
> ingenic_early_console_setup);
> serial/8250/8250_ingenic.c:OF_EARLYCON_DECLARE(jz4780_uart,
> "ingenic,jz4780-uart",
> serial/arc_uart.c:EARLYCON_DECLARE(arc_uart, arc_early_console_setup);
> serial/arc_uart.c:OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart",
> arc_early_console_setup);
> serial/bcm63xx_uart.c:OF_EARLYCON_DECLARE(bcm63xx_uart,
> "brcm,bcm6345-uart", bcm_early_console_setup);
> yamada@beagle:~/workspace/linux/drivers/tty$ git grep -e
> 'EARLYCON_DECLARE(.*_serial'
> serial/8250/8250_early.c:EARLYCON_DECLARE(uart8250, early_serial8250_setup);
> serial/8250/8250_early.c:EARLYCON_DECLARE(uart, early_serial8250_setup);
> serial/msm_serial.c:EARLYCON_DECLARE(msm_serial,
> msm_serial_early_console_setup);
> serial/msm_serial.c:OF_EARLYCON_DECLARE(msm_serial, "qcom,msm-uart",
> serial/msm_serial.c:EARLYCON_DECLARE(msm_serial_dm,
> msm_serial_early_console_setup_dm);
> serial/msm_serial.c:OF_EARLYCON_DECLARE(msm_serial_dm, "qcom,msm-uartdm",
> serial/sprd_serial.c:EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
> serial/sprd_serial.c:OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",

This brings up an important point: the names for EARLYCON_DECLARE() should not
be changed after being in at least one kernel release, since this would cause
existing command line setups to fail.

Regards,
Peter Hurley

Patch
diff mbox

diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index 245edbb..c1075c5 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -13,6 +13,7 @@ 
  */
 
 #include <linux/clk.h>
+#include <linux/console.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -34,6 +35,29 @@  struct uniphier8250_priv {
 	spinlock_t atomic_write_lock;
 };
 
+#if IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE)
+static int __init uniphier_early_console_setup(struct earlycon_device *device,
+					       const char *options)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	/* This hardware always expects MMIO32 register interface. */
+	device->port.iotype = UPIO_MEM32;
+	device->port.regshift = 2;
+
+	/*
+	 * Do not touch the divisor register in early_serial8250_setup();
+	 * we assume it has been initialized by a boot loader.
+	 */
+	device->baud = 0;
+
+	return early_serial8250_setup(device, options);
+}
+OF_EARLYCON_DECLARE(uniphier_uart, "socionext,uniphier-uart",
+		    uniphier_early_console_setup);
+#endif
+
 /*
  * The register map is slightly different from that of 8250.
  * IO callbacks must be overridden for correct access to FCR, LCR, and MCR.