Re: [PATCH v3 1/2] serial: samsung: Add support for early console

[Chanwoo Choi <cw00.choi@samsung.com>]

On 10/20/2014 08:28 PM, Marek Szyprowski wrote:
> From: Tomasz Figa <t.figa@samsung.com>
> 
> This patch adds support for early console initialized from device tree
> and kernel command line to all variants of Samsung serial driver.
> 
> Signed-off-by: Tomasz Figa <t.figa@samsung.com>
> [mszyprow: added support for command line based initialization,
>            fixed comments, added documentation]
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
> Tested-by: Alim Akhtar <alim.akhtar@samsung.com>

I tested this patchset with Exynos5 SoC.

Tested-by: Chanwoo Choi <cw00.choi@samsung.com>

Thanks,
Chanwoo Choi

> ---
>  Documentation/kernel-parameters.txt |  12 +++++
>  drivers/tty/serial/Kconfig          |   1 +
>  drivers/tty/serial/samsung.c        | 103 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 116 insertions(+)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 7dbe5ec9d9cd..24f363108ab3 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -961,6 +961,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  
>  		smh	Use ARM semihosting calls for early console.
>  
> +		s3c2410,<addr>
> +		s3c2412,<addr>
> +		s3c2440,<addr>
> +		s3c6400,<addr>
> +		s5pv210,<addr>
> +		exynos4210,<addr>
> +			Use early console provided by serial driver available
> +			on Samsung SoCs, requires selecting proper type and
> +			a correct base address of the selected UART port. The
> +			serial port must already be setup and configured.
> +			Options are not yet supported.
> +
>  	earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k]
>  			earlyprintk=vga
>  			earlyprintk=efi
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 649b784081c7..50997be6cf6d 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -241,6 +241,7 @@ config SERIAL_SAMSUNG
>  	tristate "Samsung SoC serial support"
>  	depends on PLAT_SAMSUNG || ARCH_EXYNOS
>  	select SERIAL_CORE
> +	select SERIAL_EARLYCON
>  	help
>  	  Support for the on-chip UARTs on the Samsung S3C24XX series CPUs,
>  	  providing /dev/ttySAC0, 1 and 2 (note, some machines may not
> diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
> index c78f43a481ce..8ad453a5d845 100644
> --- a/drivers/tty/serial/samsung.c
> +++ b/drivers/tty/serial/samsung.c
> @@ -1856,6 +1856,109 @@ static struct platform_driver samsung_serial_driver = {
>  
>  module_platform_driver(samsung_serial_driver);
>  
> +/*
> + * Early console.
> + */
> +
> +struct samsung_early_console_data {
> +	u32 txfull_mask;
> +};
> +
> +static void samsung_early_busyuart(struct uart_port *port)
> +{
> +	while (!(readl(port->membase + S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXFE))
> +		;
> +}
> +
> +static void samsung_early_busyuart_fifo(struct uart_port *port)
> +{
> +	struct samsung_early_console_data *data = port->private_data;
> +
> +	while (readl(port->membase + S3C2410_UFSTAT) & data->txfull_mask)
> +		;
> +}
> +
> +static void samsung_early_putc(struct uart_port *port, int c)
> +{
> +	if (readl(port->membase + S3C2410_UFCON) & S3C2410_UFCON_FIFOMODE)
> +		samsung_early_busyuart_fifo(port);
> +	else
> +		samsung_early_busyuart(port);
> +
> +	writeb(c, port->membase + S3C2410_UTXH);
> +}
> +
> +static void samsung_early_write(struct console *con, const char *s, unsigned n)
> +{
> +	struct earlycon_device *dev = con->data;
> +
> +	uart_console_write(&dev->port, s, n, samsung_early_putc);
> +}
> +
> +static int __init samsung_early_console_setup(struct earlycon_device *device,
> +					      const char *opt)
> +{
> +	if (!device->port.membase)
> +		return -ENODEV;
> +
> +	device->con->write = samsung_early_write;
> +	return 0;
> +}
> +
> +/* S3C2410 */
> +static struct samsung_early_console_data s3c2410_early_console_data = {
> +	.txfull_mask = S3C2410_UFSTAT_TXFULL,
> +};
> +
> +static int __init s3c2410_early_console_setup(struct earlycon_device *device,
> +					      const char *opt)
> +{
> +	device->port.private_data = &s3c2410_early_console_data;
> +	return samsung_early_console_setup(device, opt);
> +}
> +OF_EARLYCON_DECLARE(s3c2410, "samsung,s3c2410-uart",
> +			s3c2410_early_console_setup);
> +EARLYCON_DECLARE(s3c2410, s3c2410_early_console_setup);
> +
> +/* S3C2412, S3C2440, S3C64xx */
> +static struct samsung_early_console_data s3c2440_early_console_data = {
> +	.txfull_mask = S3C2440_UFSTAT_TXFULL,
> +};
> +
> +static int __init s3c2440_early_console_setup(struct earlycon_device *device,
> +					      const char *opt)
> +{
> +	device->port.private_data = &s3c2440_early_console_data;
> +	return samsung_early_console_setup(device, opt);
> +}
> +OF_EARLYCON_DECLARE(s3c2412, "samsung,s3c2412-uart",
> +			s3c2440_early_console_setup);
> +OF_EARLYCON_DECLARE(s3c2440, "samsung,s3c2440-uart",
> +			s3c2440_early_console_setup);
> +OF_EARLYCON_DECLARE(s3c6400, "samsung,s3c6400-uart",
> +			s3c2440_early_console_setup);
> +EARLYCON_DECLARE(s3c2412, s3c2440_early_console_setup);
> +EARLYCON_DECLARE(s3c2440, s3c2440_early_console_setup);
> +EARLYCON_DECLARE(s3c6400, s3c2440_early_console_setup);
> +
> +/* S5PV210, EXYNOS */
> +static struct samsung_early_console_data s5pv210_early_console_data = {
> +	.txfull_mask = S5PV210_UFSTAT_TXFULL,
> +};
> +
> +static int __init s5pv210_early_console_setup(struct earlycon_device *device,
> +					      const char *opt)
> +{
> +	device->port.private_data = &s5pv210_early_console_data;
> +	return samsung_early_console_setup(device, opt);
> +}
> +OF_EARLYCON_DECLARE(s5pv210, "samsung,s5pv210-uart",
> +			s5pv210_early_console_setup);
> +OF_EARLYCON_DECLARE(exynos4210, "samsung,exynos4210-uart",
> +			s5pv210_early_console_setup);
> +EARLYCON_DECLARE(s5pv210, s5pv210_early_console_setup);
> +EARLYCON_DECLARE(exynos4210, s5pv210_early_console_setup);
> +
>  MODULE_ALIAS("platform:samsung-uart");
>  MODULE_DESCRIPTION("Samsung SoC Serial port driver");
>  MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
>