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serial: sh-sci: console runtime PM support (revisit)

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The commit 1ba7622094 (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: Teppei Kamijou <teppei.kamijou.yb@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Teppei Kamijou 2012-11-16 10:51:55 +09:00 committed by Greg Kroah-Hartman
parent 00cadbfd1e
commit 0174e5ca82
1 changed files with 16 additions and 11 deletions
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27
drivers/tty/serial/sh-sci.c
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@ -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);
}