gpio: davinci: Add support for system suspend/resume PM

Add support for system suspend/resume PM hooks, save the
register context of all the required gpio registers on suspend
and restore context on the resume.
Signed-off-by: Devarsh Thakkar <devarsht@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

drivers/gpio/gpio-davinci.c

@@ -22,6 +22,7 @@
 #include <linux/platform_data/gpio-davinci.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/spinlock.h>
+#include <linux/pm_runtime.h>
 
 #include <asm-generic/gpio.h>
 
@@ -62,6 +63,8 @@ struct davinci_gpio_controller {
 	void __iomem		*regs[MAX_REGS_BANKS];
 	int			gpio_unbanked;
 	int			irqs[MAX_INT_PER_BANK];
+	struct davinci_gpio_regs context[MAX_REGS_BANKS];
+	u32			binten_context;
 };
 
 static inline u32 __gpio_mask(unsigned gpio)
@@ -622,6 +625,85 @@ static int davinci_gpio_irq_setup(struct platform_device *pdev)
 	return 0;
 }
 
+static void davinci_gpio_save_context(struct davinci_gpio_controller *chips,
+				      u32 nbank)
+{
+	struct davinci_gpio_regs __iomem *g;
+	struct davinci_gpio_regs *context;
+	u32 bank;
+	void __iomem *base;
+
+	base = chips->regs[0] - offset_array[0];
+	chips->binten_context = readl_relaxed(base + BINTEN);
+
+	for (bank = 0; bank < nbank; bank++) {
+		g = chips->regs[bank];
+		context = &chips->context[bank];
+		context->dir = readl_relaxed(&g->dir);
+		context->set_data = readl_relaxed(&g->set_data);
+		context->set_rising = readl_relaxed(&g->set_rising);
+		context->set_falling = readl_relaxed(&g->set_falling);
+	}
+
+	/* Clear Bank interrupt enable bit */
+	writel_relaxed(0, base + BINTEN);
+
+	/* Clear all interrupt status registers */
+	writel_relaxed(GENMASK(31, 0), &g->intstat);
+}
+
+static void davinci_gpio_restore_context(struct davinci_gpio_controller *chips,
+					 u32 nbank)
+{
+	struct davinci_gpio_regs __iomem *g;
+	struct davinci_gpio_regs *context;
+	u32 bank;
+	void __iomem *base;
+
+	base = chips->regs[0] - offset_array[0];
+
+	if (readl_relaxed(base + BINTEN) != chips->binten_context)
+		writel_relaxed(chips->binten_context, base + BINTEN);
+
+	for (bank = 0; bank < nbank; bank++) {
+		g = chips->regs[bank];
+		context = &chips->context[bank];
+		if (readl_relaxed(&g->dir) != context->dir)
+			writel_relaxed(context->dir, &g->dir);
+		if (readl_relaxed(&g->set_data) != context->set_data)
+			writel_relaxed(context->set_data, &g->set_data);
+		if (readl_relaxed(&g->set_rising) != context->set_rising)
+			writel_relaxed(context->set_rising, &g->set_rising);
+		if (readl_relaxed(&g->set_falling) != context->set_falling)
+			writel_relaxed(context->set_falling, &g->set_falling);
+	}
+}
+
+static int davinci_gpio_suspend(struct device *dev)
+{
+	struct davinci_gpio_controller *chips = dev_get_drvdata(dev);
+	struct davinci_gpio_platform_data *pdata = dev_get_platdata(dev);
+	u32 nbank = DIV_ROUND_UP(pdata->ngpio, 32);
+
+	davinci_gpio_save_context(chips, nbank);
+
+	return 0;
+}
+
+static int davinci_gpio_resume(struct device *dev)
+{
+	struct davinci_gpio_controller *chips = dev_get_drvdata(dev);
+	struct davinci_gpio_platform_data *pdata = dev_get_platdata(dev);
+	u32 nbank = DIV_ROUND_UP(pdata->ngpio, 32);
+
+	davinci_gpio_restore_context(chips, nbank);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_DEV_PM_OPS(davinci_gpio_dev_pm_ops, davinci_gpio_suspend,
+			 davinci_gpio_resume);
+
 static const struct of_device_id davinci_gpio_ids[] = {
 	{ .compatible = "ti,keystone-gpio", keystone_gpio_get_irq_chip},
 	{ .compatible = "ti,am654-gpio", keystone_gpio_get_irq_chip},
@@ -634,6 +716,7 @@ static struct platform_driver davinci_gpio_driver = {
 	.probe		= davinci_gpio_probe,
 	.driver		= {
 		.name		= "davinci_gpio",
+		.pm = pm_sleep_ptr(&davinci_gpio_dev_pm_ops),
 		.of_match_table	= of_match_ptr(davinci_gpio_ids),
 	},
 };