Commit 39f80919 authored by Lanqing Liu's avatar Lanqing Liu Committed by Greg Kroah-Hartman
Browse files

serial: sprd: Add polling IO support 



In order to access the UART without the interrupts, the kernel uses
the basic polling methods for IO with the device. With these methods
implemented, it is now possible to enable kgdb during early boot over serial.

Signed-off-by: default avatarLanqing Liu <liuhhome@gmail.com>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linaro.org>
Tested-by: default avatarBaolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/f112a741c053ac5fb0637e2f058be81e17f78ccc.1568862391.git.liuhhome@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 76c38d30

drivers/tty/serial/sprd_serial.c

+33 −0
Original line number Diff line number Diff line
@@ -919,6 +919,34 @@ static void sprd_pm(struct uart_port *port, unsigned int state, 
	}

}



#ifdef CONFIG_CONSOLE_POLL

static int sprd_poll_init(struct uart_port *port)

{

	if (port->state->pm_state != UART_PM_STATE_ON) {

		sprd_pm(port, UART_PM_STATE_ON, 0);

		port->state->pm_state = UART_PM_STATE_ON;

	}



	return 0;

}



static int sprd_poll_get_char(struct uart_port *port)

{

	while (!(serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK))

		cpu_relax();



	return serial_in(port, SPRD_RXD);

}



static void sprd_poll_put_char(struct uart_port *port, unsigned char ch)

{

	while (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)

		cpu_relax();



	serial_out(port, SPRD_TXD, ch);

}

#endif



static const struct uart_ops serial_sprd_ops = {

	.tx_empty = sprd_tx_empty,

	.get_mctrl = sprd_get_mctrl,
@@ -936,6 +964,11 @@ static const struct uart_ops serial_sprd_ops = { 
	.config_port = sprd_config_port,

	.verify_port = sprd_verify_port,

	.pm = sprd_pm,

#ifdef CONFIG_CONSOLE_POLL

	.poll_init	= sprd_poll_init,

	.poll_get_char	= sprd_poll_get_char,

	.poll_put_char	= sprd_poll_put_char,

#endif

};



#ifdef CONFIG_SERIAL_SPRD_CONSOLE

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