[PATCH v4 1/1] OMAP2: Spi: Force CS to be in inactive state after off-mode transition

[Gregory CLEMENT <gregory.clement@free-electrons.com>]

When SPI wake up from OFF mode, CS is in the wrong state: force it to 
the inactive state.

During the system life, I monitored the CS behavior using a oscilloscope.
I also activated debug in omap2_mcspi, so I saw when driver disable the 
clocks and restore context when device is not used.
Each time the CS was in the correct state.
It was only when system was put suspend to ram with off-mode activated 
that on resume the CS was in wrong state( ie activated).

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
  drivers/spi/omap2_mcspi.c |   35 +++++++++++++++++++++++++++++++++++
  1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index 2a651e6..43d92fc 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -1305,11 +1305,46 @@ static int __exit omap2_mcspi_remove(struct 
platform_device *pdev)
  /* work with hotplug and coldplug */
  MODULE_ALIAS("platform:omap2_mcspi");
  +#ifdef	CONFIG_PM
+/* When SPI wake up from off-mode, CS is in activate state. If it was in
+ * unactive state when driver was suspend, then force it to unactive 
state at
+ * wake up.
+ */
+static int omap2_mcspi_resume(struct platform_device *pdev)
+{
+	struct spi_master	*master;
+	struct omap2_mcspi_cs *cs;
+	struct omap2_mcspi	*mcspi;
+
+	master = dev_get_drvdata(&pdev->dev);
+	mcspi = spi_master_get_devdata(master);
+	omap2_mcspi_enable_clocks(mcspi);
+	list_for_each_entry(cs, &omap2_mcspi_ctx[master->bus_num - 1].cs,
+			    node) {
+		if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE) == 0) {
+
+			/* We need to togle CS state for OMAP take this
+			 * change in account.
+			 */
+			MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 1);
+			__raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
+			MOD_REG_BIT(cs->chconf0, OMAP2_MCSPI_CHCONF_FORCE, 0);
+			__raw_writel(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
+		}
+	}
+	omap2_mcspi_disable_clocks(mcspi);
+	return 0;
+}
+#else
+#define	omap2_mcspi_resume	NULL
+#endif
+
  static struct platform_driver omap2_mcspi_driver = {
  	.driver = {
  		.name =		"omap2_mcspi",
  		.owner =	THIS_MODULE,
  	},
+	.resume =	omap2_mcspi_resume,
  	.remove =	__exit_p(omap2_mcspi_remove),
  };
  -- 1.7.0.4