Subject: [PATCH] serial: cadence: Add generic earlycon support

From: [email-masked] (Michal Simek)
Date: Thu, 18 Sep 2014 07:15:36 +0200

On 09/17/2014 10:58 PM, Greg Kroah-Hartman wrote:
> On Wed, Sep 17, 2014 at 03:44:58PM +0200, Michal Simek wrote:
>> Hi Greg,
>>
>> On 09/10/2014 12:43 PM, Michal Simek wrote:
>>> Add earlycon support for the cadence serial port.
>>> This is based on recent patches:
>>> "tty/serial: pl011: add generic earlycon support"
>>> (sha1: 0d3c673e7881e691991b2a4745bd4f149603baa2)
>>> "tty/serial: add arm/arm64 semihosting earlycon"
>>> (sha1: d50d7269ebcb438afa346cdffce0f4e2a1b9e831)
>>>
>>> Signed-off-by: Michal Simek <[email-masked]>
>>> ---
>>>
>>>  Documentation/kernel-parameters.txt |  6 ++++++
>>>  drivers/tty/serial/Kconfig          |  1 +
>>>  drivers/tty/serial/xilinx_uartps.c  | 19 +++++++++++++++++++
>>>  3 files changed, 26 insertions(+)
>>>
>>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>>> index a8eb6afce6a4..97055dc43167 100644
>>> --- a/Documentation/kernel-parameters.txt
>>> +++ b/Documentation/kernel-parameters.txt
>>> @@ -921,6 +921,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>>>
>>>  	earlycon=	[KNL] Output early console device and options.
>>>
>>> +		cdns,<addr>
>>> +			Start an early, polled-mode console on a cadence serial
>>> +			port at the specified address. The cadence serial port
>>> +			must already be setup and configured. Options are not
>>> +			yet supported.
>>> +
>>>  		uart[8250],io,<addr>[,options]
>>>  		uart[8250],mmio,<addr>[,options]
>>>  		uart[8250],mmio32,<addr>[,options]
>>> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
>>> index b4d61e6bf28c..72fd2b6e2241 100644
>>> --- a/drivers/tty/serial/Kconfig
>>> +++ b/drivers/tty/serial/Kconfig
>>> @@ -1411,6 +1411,7 @@ config SERIAL_XILINX_PS_UART_CONSOLE
>>>  	bool "Cadence UART console support"
>>>  	depends on SERIAL_XILINX_PS_UART=y
>>>  	select SERIAL_CORE_CONSOLE
>>> +	select SERIAL_EARLYCON
>>>  	help
>>>  	  Enable a Cadence UART port to be the system console.
>>>
>>> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
>>> index 01951d27cc03..675f3fe068f6 100644
>>> --- a/drivers/tty/serial/xilinx_uartps.c
>>> +++ b/drivers/tty/serial/xilinx_uartps.c
>>> @@ -1051,6 +1051,25 @@ static void cdns_uart_console_putchar(struct uart_port *port, int ch)
>>>  	cdns_uart_writel(ch, CDNS_UART_FIFO_OFFSET);
>>>  }
>>>
>>> +static void cdns_early_write(struct console *con, const char *s, unsigned n)
>>> +{
>>> +	struct earlycon_device *dev = con->data;
>>> +
>>> +	uart_console_write(&dev->port, s, n, cdns_uart_console_putchar);
>>> +}
>>> +
>>> +static int __init cdns_early_console_setup(struct earlycon_device *device,
>>> +					   const char *opt)
>>> +{
>>> +	if (!device->port.membase)
>>> +		return -ENODEV;
>>> +
>>> +	device->con->write = cdns_early_write;
>>> +
>>> +	return 0;
>>> +}
>>> +EARLYCON_DECLARE(cdns, cdns_early_console_setup);
>>> +
>>>  /**
>>>   * cdns_uart_console_write - perform write operation
>>>   * @co: Console handle
>>> --
>>> 1.8.2.3
>>>
>>
>> Any problem with this patch?
> 
> Don't know, it's in my todo queue which is really long at the moment...
> 

Thanks for confirmation that it is in your todo queue.
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform

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