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Commit 0174e5ca authored by Teppei Kamijou's avatar Teppei Kamijou Committed by Greg Kroah-Hartman
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serial: sh-sci: console runtime PM support (revisit) 



The commit 1ba76220 (serial: sh-sci: console Runtime PM support,
from Magnus Damm <damm@opensource.se>, 2011-08-03), tried to support
console runtime PM, but unfortunately it didn't work for us for some
reason.  We did not investigated further at that time, instead would
like to propose a different approach.

In Linux tty/serial world, to get console PM work properly, a serial
client driver does not have to maintain .runtime_suspend()/..resume()
calls itself, but can leave console power power management handling to
the serial core driver.

This patch moves the sh-sci driver in that direction.

Notes:

* There is room to optimize console runtime PM more aggressively by
  maintaining additional local runtime PM calls, but as a first step
  having .pm() operation would suffice.

* We still have a couple of direct calls to sci_port_enable/..disable
  left in the driver.  We have to live with them, because they're out
  of serial core's help.

Signed-off-by: default avatarTeppei Kamijou <teppei.kamijou.yb@renesas.com>
Signed-off-by: default avatarShinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 00cadbfd

drivers/tty/serial/sh-sci.c

+16 −11
Original line number Diff line number Diff line
@@ -1747,8 +1747,6 @@ static int sci_startup(struct uart_port *port) 


	dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);



	sci_port_enable(s);



	ret = sci_request_irq(s);

	if (unlikely(ret < 0))

		return ret;
@@ -1772,8 +1770,6 @@ static void sci_shutdown(struct uart_port *port) 


	sci_free_dma(port);

	sci_free_irq(s);



	sci_port_disable(s);

}



static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps,
@@ -1922,6 +1918,21 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, 
	sci_port_disable(s);

}



static void sci_pm(struct uart_port *port, unsigned int state,

		   unsigned int oldstate)

{

	struct sci_port *sci_port = to_sci_port(port);



	switch (state) {

	case 3:

		sci_port_disable(sci_port);

		break;

	default:

		sci_port_enable(sci_port);

		break;

	}

}



static const char *sci_type(struct uart_port *port)

{

	switch (port->type) {
@@ -2043,6 +2054,7 @@ static struct uart_ops sci_uart_ops = { 
	.startup	= sci_startup,

	.shutdown	= sci_shutdown,

	.set_termios	= sci_set_termios,

	.pm		= sci_pm,

	.type		= sci_type,

	.release_port	= sci_release_port,

	.request_port	= sci_request_port,
@@ -2196,16 +2208,12 @@ static void serial_console_write(struct console *co, const char *s, 
	struct uart_port *port = &sci_port->port;

	unsigned short bits;



	sci_port_enable(sci_port);



	uart_console_write(port, s, count, serial_console_putchar);



	/* wait until fifo is empty and last bit has been transmitted */

	bits = SCxSR_TDxE(port) | SCxSR_TEND(port);

	while ((serial_port_in(port, SCxSR) & bits) != bits)

		cpu_relax();



	sci_port_disable(sci_port);

}



static int __devinit serial_console_setup(struct console *co, char *options)
@@ -2237,12 +2245,9 @@ static int __devinit serial_console_setup(struct console *co, char *options) 
	if (unlikely(ret != 0))

		return ret;



	sci_port_enable(sci_port);



	if (options)

		uart_parse_options(options, &baud, &parity, &bits, &flow);



	/* TODO: disable clock */

	return uart_set_options(port, co, baud, parity, bits, flow);

}