[PATCH] serial: sh-sci: console Runtime PM support

[PATCH] serial: sh-sci: console Runtime PM support

[Magnus Damm]

From: Magnus Damm <damm@opensource.se>

Add Runtime PM context save/restore support to
the SCIF driver. Tested on the AP4EVB console.

Signed-off-by: Magnus Damm <damm@opensource.se>
---

 Rebased version of prototype patch sent 20110630.

 drivers/tty/serial/sh-sci.c |   68 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 58 insertions(+), 10 deletions(-)

--- 0003/drivers/tty/serial/sh-sci.c
+++ work/drivers/tty/serial/sh-sci.c	2011-08-03 11:58:53.000000000 +0900
@@ -96,6 +96,12 @@ struct sci_port {
 #endif
 
 	struct notifier_block		freq_transition;
+
+#ifdef CONFIG_SERIAL_SH_SCI_CONSOLE
+	unsigned short saved_smr;
+	unsigned short saved_fcr;
+	unsigned char saved_brr;
+#endif
 };
 
 /* Function prototypes */
@@ -1634,11 +1640,25 @@ static unsigned int sci_scbrr_calc(unsig
 	return ((freq + 16 * bps) / (32 * bps) - 1);
 }
 
+static void sci_reset(struct uart_port *port)
+{
+	unsigned int status;
+
+	do {
+		status = sci_in(port, SCxSR);
+	} while (!(status & SCxSR_TEND(port)));
+
+	sci_out(port, SCSCR, 0x00);	/* TE=0, RE=0, CKE1=0 */
+
+	if (port->type != PORT_SCI)
+		sci_out(port, SCFCR, SCFCR_RFRST | SCFCR_TFRST);
+}
+
 static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 			    struct ktermios *old)
 {
 	struct sci_port *s = to_sci_port(port);
-	unsigned int status, baud, smr_val, max_baud;
+	unsigned int baud, smr_val, max_baud;
 	int t = -1;
 	u16 scfcr = 0;
 
@@ -1658,14 +1678,7 @@ static void sci_set_termios(struct uart_
 
 	sci_port_enable(s);
 
-	do {
-		status = sci_in(port, SCxSR);
-	} while (!(status & SCxSR_TEND(port)));
-
-	sci_out(port, SCSCR, 0x00);	/* TE=0, RE=0, CKE1=0 */
-
-	if (port->type != PORT_SCI)
-		sci_out(port, SCFCR, scfcr | SCFCR_RFRST | SCFCR_TFRST);
+	sci_reset(port);
 
 	smr_val = sci_in(port, SCSMR) & 3;
 
@@ -2037,7 +2050,8 @@ static int __devinit serial_console_setu
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 
-	/* TODO: disable clock */
+	sci_port_disable(sci_port);
+
 	return uart_set_options(port, co, baud, parity, bits, flow);
 }
 
@@ -2080,6 +2094,36 @@ static int __devinit sci_probe_earlyprin
 	return 0;
 }
 
+#define uart_console(port)	((port)->cons->index = (port)->line)
+
+static int sci_runtime_suspend(struct device *dev)
+{
+	struct sci_port *sci_port = dev_get_drvdata(dev);
+	struct uart_port *port = &sci_port->port;
+
+	if (uart_console(port)) {
+		sci_port->saved_smr = sci_in(port, SCSMR);
+		sci_port->saved_brr = sci_in(port, SCBRR);
+		sci_port->saved_fcr = sci_in(port, SCFCR);
+	}
+	return 0;
+}
+
+static int sci_runtime_resume(struct device *dev)
+{
+	struct sci_port *sci_port = dev_get_drvdata(dev);
+	struct uart_port *port = &sci_port->port;
+
+	if (uart_console(port)) {
+		sci_reset(port);
+		sci_out(port, SCSMR, sci_port->saved_smr);
+		sci_out(port, SCBRR, sci_port->saved_brr);
+		sci_out(port, SCFCR, sci_port->saved_fcr);
+		sci_out(port, SCSCR, sci_port->cfg->scscr);
+	}
+	return 0;
+}
+
 #define SCI_CONSOLE	(&serial_console)
 
 #else
@@ -2089,6 +2133,8 @@ static inline int __devinit sci_probe_ea
 }
 
 #define SCI_CONSOLE	NULL
+#define sci_runtime_suspend	NULL
+#define sci_runtime_resume	NULL
 
 #endif /* CONFIG_SERIAL_SH_SCI_CONSOLE */
 
@@ -2204,6 +2250,8 @@ static int sci_resume(struct device *dev
 }
 
 static const struct dev_pm_ops sci_dev_pm_ops = {
+	.runtime_suspend = sci_runtime_suspend,
+	.runtime_resume = sci_runtime_resume,
 	.suspend	= sci_suspend,
 	.resume		= sci_resume,
 };

Re: [PATCH] serial: sh-sci: console Runtime PM support

[Simon Horman]

On Wed, Aug 03, 2011 at 12:47:36PM +0900, Magnus Damm wrote:
> From: Magnus Damm <damm@opensource.se>
> 
> Add Runtime PM context save/restore support to
> the SCIF driver. Tested on the AP4EVB console.

Hi Magnus,

could you explain in a little more detail how this was tested?
Also, is this likely to work on other boards? E.g the AP4 Mackerel?

Re: [PATCH] serial: sh-sci: console Runtime PM support

[Magnus Damm]

Hi Simon,

On Thu, Aug 4, 2011 at 10:04 AM, Simon Horman <horms@verge.net.au> wrote:
> On Wed, Aug 03, 2011 at 12:47:36PM +0900, Magnus Damm wrote:
>> From: Magnus Damm <damm@opensource.se>
>>
>> Add Runtime PM context save/restore support to
>> the SCIF driver. Tested on the AP4EVB console.
>
> Hi Magnus,
>
> could you explain in a little more detail how this was tested?

This has been tested on AP4EVB with and without power domain support.
For sh7372 the serial ports are located in the A3SP power domain which
has experimental software support through some prototype patches
earlier posted to the linux-sh list. I intend to up-port these
prototype patches to 3.1-rc in the not so distant future.

> Also, is this likely to work on other boards? E.g the AP4 Mackerel?

The Runtime PM support provided by this patch should work with any
SCI/SCIF/SCIFA/SCIFB hardware block regardless of SoC type. So yes,
both AP4EVB and Mackerel should work just fine.

Thanks,

/ magnus