2022-02-16 20:57:50

by Michael Walle

Subject: [PATCH] tty: serial: atmel: add earlycon support

Add early console support which relies on the bootloader for the
initialization of the UART.
Please note, that the compatibles are taken from at91-usart MFD
driver.

Signed-off-by: Michael Walle <[email protected]>
---
drivers/tty/serial/atmel_serial.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 2d09a89974a2..50fc6d51ff0d 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2673,6 +2673,30 @@ static struct console atmel_console = {
.data = &atmel_uart,
};

+static void atmel_serial_early_write(struct console *con, const char *s,
+ unsigned int n)
+{
+ struct earlycon_device *dev = con->data;
+
+ uart_console_write(&dev->port, s, n, atmel_console_putchar);
+}
+
+static int __init atmel_early_console_setup(struct earlycon_device *device,
+ const char *options)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ device->con->write = atmel_serial_early_write;
+
+ return 0;
+}
+
+OF_EARLYCON_DECLARE(atmelserial, "atmel,at91rm9200-usart",
+ atmel_early_console_setup);
+OF_EARLYCON_DECLARE(atmelserial, "atmel,at91sam9260-usart",
+ atmel_early_console_setup);
+
#define ATMEL_CONSOLE_DEVICE (&atmel_console)

#else
--
2.30.2

2022-02-17 12:03:25

by Michael Walle

Subject: Re: [PATCH] tty: serial: atmel: add earlycon support

Hi,

Am 2022-02-17 10:12, schrieb [email protected]:
> On 16.02.2022 18:18, Michael Walle wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know
>> the content is safe
>>
>> Add early console support which relies on the bootloader for the
>> initialization of the UART.
>> Please note, that the compatibles are taken from at91-usart MFD
>> driver.
>>
>> Signed-off-by: Michael Walle <[email protected]>
>> ---
>> drivers/tty/serial/atmel_serial.c | 24 ++++++++++++++++++++++++
>> 1 file changed, 24 insertions(+)
>>
>> diff --git a/drivers/tty/serial/atmel_serial.c
>> b/drivers/tty/serial/atmel_serial.c
>> index 2d09a89974a2..50fc6d51ff0d 100644
>> --- a/drivers/tty/serial/atmel_serial.c
>> +++ b/drivers/tty/serial/atmel_serial.c
>> @@ -2673,6 +2673,30 @@ static struct console atmel_console = {
>> .data = &atmel_uart,
>> };
>>
>> +static void atmel_serial_early_write(struct console *con, const char
>> *s,
>> + unsigned int n)
>> +{
>> + struct earlycon_device *dev = con->data;
>> +
>> + uart_console_write(&dev->port, s, n, atmel_console_putchar);
>> +}
>> +
>> +static int __init atmel_early_console_setup(struct earlycon_device
>> *device,
>> + const char *options)
>> +{
>> + if (!device->port.membase)
>> + return -ENODEV;
>> +
>> + device->con->write = atmel_serial_early_write;
>> +
>> + return 0;
>> +}
>> +
>> +OF_EARLYCON_DECLARE(atmelserial, "atmel,at91rm9200-usart",
>> + atmel_early_console_setup);
>> +OF_EARLYCON_DECLARE(atmelserial, "atmel,at91sam9260-usart",
>
>
> For consistency with the rest of the naming in this file could you name
> it
> atmel_serial?

Sure, I don't have an opinion on that. It's done both ways:
omap-serial.c:OF_EARLYCON_DECLARE(omapserial, "ti,omap2-uart",
early_omap_serial_setup);
bcm63xx_uart.c:OF_EARLYCON_DECLARE(bcm63xx_uart, "brcm,bcm6345-uart",
bcm_early_console_setup);
...

> Also, it would be good to select SERIAL_EARLYCON in Kconfig to have it
> available also for production w/o changing defconfigs.

Ahh, missed that these are enabled for all the other Kconfig symbols.
Will add it to SERIAL_ATMEL_CONSOLE.

-michael