gpio/omap: ensure gpio context is initialised

Commit a2797bea (gpio/omap: force restore if context loss is not
detectable) broke gpio support for OMAP when booting with device-tree
because a restore of the gpio context being performed without ever
initialising the gpio context. In other words, the context restored was
bad.

This problem could also occur in the non device-tree case, however, it
is much less likely because when booting without device-tree we can
detect context loss via a platform specific API and so context restore
is performed less often.

Nevertheless we should ensure that the gpio context is initialised
on the first pm-runtime resume for gpio banks that could lose their
state regardless of whether we are booting with device-tree or not.

The context loss count was being initialised on the first pm-runtime
suspend following a resume, by populating the get_count_loss_count()
function pointer after the first pm-runtime resume. To make the code
more readable and logical, initialise the context loss count on the
first pm-runtime resume if the context is not yet valid.
Reported-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Acked-by: Santosh Shilimkar<santosh.shilimkar@ti.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-omap.c

@@ -69,6 +69,7 @@ struct gpio_bank {
 	bool is_mpuio;
 	bool dbck_flag;
 	bool loses_context;
+	bool context_valid;
 	int stride;
 	u32 width;
 	int context_loss_count;
@@ -1128,6 +1129,10 @@ static int omap_gpio_probe(struct platform_device *pdev)
 			bank->loses_context = true;
 	} else {
 		bank->loses_context = pdata->loses_context;
+
+		if (bank->loses_context)
+			bank->get_context_loss_count =
+				pdata->get_context_loss_count;
 	}
 
 
@@ -1178,9 +1183,6 @@ static int omap_gpio_probe(struct platform_device *pdev)
 	omap_gpio_chip_init(bank);
 	omap_gpio_show_rev(bank);
 
-	if (bank->loses_context)
-		bank->get_context_loss_count = pdata->get_context_loss_count;
-
 	pm_runtime_put(bank->dev);
 
 	list_add_tail(&bank->node, &omap_gpio_list);
@@ -1259,6 +1261,8 @@ static int omap_gpio_runtime_suspend(struct device *dev)
 	return 0;
 }
 
+static void omap_gpio_init_context(struct gpio_bank *p);
+
 static int omap_gpio_runtime_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
@@ -1268,6 +1272,20 @@ static int omap_gpio_runtime_resume(struct device *dev)
 	int c;
 
 	spin_lock_irqsave(&bank->lock, flags);
+
+	/*
+	 * On the first resume during the probe, the context has not
+	 * been initialised and so initialise it now. Also initialise
+	 * the context loss count.
+	 */
+	if (bank->loses_context && !bank->context_valid) {
+		omap_gpio_init_context(bank);
+
+		if (bank->get_context_loss_count)
+			bank->context_loss_count =
+				bank->get_context_loss_count(bank->dev);
+	}
+
 	_gpio_dbck_enable(bank);
 
 	/*
@@ -1384,6 +1402,29 @@ void omap2_gpio_resume_after_idle(void)
 }
 
 #if defined(CONFIG_PM_RUNTIME)
+static void omap_gpio_init_context(struct gpio_bank *p)
+{
+	struct omap_gpio_reg_offs *regs = p->regs;
+	void __iomem *base = p->base;
+
+	p->context.ctrl		= __raw_readl(base + regs->ctrl);
+	p->context.oe		= __raw_readl(base + regs->direction);
+	p->context.wake_en	= __raw_readl(base + regs->wkup_en);
+	p->context.leveldetect0	= __raw_readl(base + regs->leveldetect0);
+	p->context.leveldetect1	= __raw_readl(base + regs->leveldetect1);
+	p->context.risingdetect	= __raw_readl(base + regs->risingdetect);
+	p->context.fallingdetect = __raw_readl(base + regs->fallingdetect);
+	p->context.irqenable1	= __raw_readl(base + regs->irqenable);
+	p->context.irqenable2	= __raw_readl(base + regs->irqenable2);
+
+	if (regs->set_dataout && p->regs->clr_dataout)
+		p->context.dataout = __raw_readl(base + regs->set_dataout);
+	else
+		p->context.dataout = __raw_readl(base + regs->dataout);
+
+	p->context_valid = true;
+}
+
 static void omap_gpio_restore_context(struct gpio_bank *bank)
 {
 	__raw_writel(bank->context.wake_en,
@@ -1421,6 +1462,7 @@ static void omap_gpio_restore_context(struct gpio_bank *bank)
 #else
 #define omap_gpio_runtime_suspend NULL
 #define omap_gpio_runtime_resume NULL
+static void omap_gpio_init_context(struct gpio_bank *p) {}
 #endif
 
 static const struct dev_pm_ops gpio_pm_ops = {