pwm: ftm: Add Power Management support for FTM PWM

Add PM support for FTM PWM driver using callback function suspend
and resume in .driver.pm of platform_driver.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-fsl-ftm.c

@@ -17,6 +17,7 @@
 #include <linux/mutex.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
+#include <linux/pm.h>
 #include <linux/pwm.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
@@ -436,7 +437,7 @@ static int fsl_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(base))
 		return PTR_ERR(base);
 
-	fpc->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
+	fpc->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "ftm_sys", base,
 						&fsl_pwm_regmap_config);
 	if (IS_ERR(fpc->regmap)) {
 		dev_err(&pdev->dev, "regmap init failed\n");
@@ -487,6 +488,51 @@ static int fsl_pwm_remove(struct platform_device *pdev)
 	return pwmchip_remove(&fpc->chip);
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int fsl_pwm_suspend(struct device *dev)
+{
+	struct fsl_pwm_chip *fpc = dev_get_drvdata(dev);
+	u32 val;
+
+	regcache_cache_only(fpc->regmap, true);
+	regcache_mark_dirty(fpc->regmap);
+
+	/* read from cache */
+	regmap_read(fpc->regmap, FTM_OUTMASK, &val);
+	if ((val & 0xFF) != 0xFF) {
+		clk_disable_unprepare(fpc->clk[FSL_PWM_CLK_CNTEN]);
+		clk_disable_unprepare(fpc->clk[fpc->cnt_select]);
+		clk_disable_unprepare(fpc->clk[FSL_PWM_CLK_SYS]);
+	}
+
+	return 0;
+}
+
+static int fsl_pwm_resume(struct device *dev)
+{
+	struct fsl_pwm_chip *fpc = dev_get_drvdata(dev);
+	u32 val;
+
+	/* read from cache */
+	regmap_read(fpc->regmap, FTM_OUTMASK, &val);
+	if ((val & 0xFF) != 0xFF) {
+		clk_prepare_enable(fpc->clk[FSL_PWM_CLK_SYS]);
+		clk_prepare_enable(fpc->clk[fpc->cnt_select]);
+		clk_prepare_enable(fpc->clk[FSL_PWM_CLK_CNTEN]);
+	}
+
+	/* restore all registers from cache */
+	regcache_cache_only(fpc->regmap, false);
+	regcache_sync(fpc->regmap);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops fsl_pwm_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(fsl_pwm_suspend, fsl_pwm_resume)
+};
+
 static const struct of_device_id fsl_pwm_dt_ids[] = {
 	{ .compatible = "fsl,vf610-ftm-pwm", },
 	{ /* sentinel */ }
@@ -497,6 +543,7 @@ static struct platform_driver fsl_pwm_driver = {
 	.driver = {
 		.name = "fsl-ftm-pwm",
 		.of_match_table = fsl_pwm_dt_ids,
+		.pm = &fsl_pwm_pm_ops,
 	},
 	.probe = fsl_pwm_probe,
 	.remove = fsl_pwm_remove,