ASoC: img-spdif-out: Add suspend / resume handling

Implement suspend and resume callbacks to save and restore register
state, to support platforms where the power is disabled during suspend.

In future the driver could be converted to use regmap which would
simplify the suspend and resume code.
Signed-off-by: Ed Blake <ed.blake@sondrel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/img/img-spdif-out.c

@@ -47,6 +47,9 @@ struct img_spdif_out {
 	struct snd_dmaengine_dai_dma_data dma_data;
 	struct device *dev;
 	struct reset_control *rst;
+	u32 suspend_ctl;
+	u32 suspend_csl;
+	u32 suspend_csh;
 };
 
 static int img_spdif_out_runtime_suspend(struct device *dev)
@@ -414,6 +417,46 @@ static int img_spdif_out_dev_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int img_spdif_out_suspend(struct device *dev)
+{
+	struct img_spdif_out *spdif = dev_get_drvdata(dev);
+	int ret;
+
+	if (pm_runtime_status_suspended(dev)) {
+		ret = img_spdif_out_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	spdif->suspend_ctl = img_spdif_out_readl(spdif, IMG_SPDIF_OUT_CTL);
+	spdif->suspend_csl = img_spdif_out_readl(spdif, IMG_SPDIF_OUT_CSL);
+	spdif->suspend_csh = img_spdif_out_readl(spdif, IMG_SPDIF_OUT_CSH_UV);
+
+	img_spdif_out_runtime_suspend(dev);
+
+	return 0;
+}
+
+static int img_spdif_out_resume(struct device *dev)
+{
+	struct img_spdif_out *spdif = dev_get_drvdata(dev);
+	int ret;
+
+	ret = img_spdif_out_runtime_resume(dev);
+	if (ret)
+		return ret;
+
+	img_spdif_out_writel(spdif, spdif->suspend_ctl, IMG_SPDIF_OUT_CTL);
+	img_spdif_out_writel(spdif, spdif->suspend_csl, IMG_SPDIF_OUT_CSL);
+	img_spdif_out_writel(spdif, spdif->suspend_csh, IMG_SPDIF_OUT_CSH_UV);
+
+	if (pm_runtime_status_suspended(dev))
+		img_spdif_out_runtime_suspend(dev);
+
+	return 0;
+}
+#endif
 static const struct of_device_id img_spdif_out_of_match[] = {
 	{ .compatible = "img,spdif-out" },
 	{}
@@ -423,6 +466,7 @@ MODULE_DEVICE_TABLE(of, img_spdif_out_of_match);
 static const struct dev_pm_ops img_spdif_out_pm_ops = {
 	SET_RUNTIME_PM_OPS(img_spdif_out_runtime_suspend,
 			   img_spdif_out_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(img_spdif_out_suspend, img_spdif_out_resume)
 };
 
 static struct platform_driver img_spdif_out_driver = {