ASoC: img-i2s-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-i2s-out.c

@@ -63,6 +63,8 @@ struct img_i2s_out {
 	unsigned int active_channels;
 	struct reset_control *rst;
 	struct snd_soc_dai_driver dai_driver;
+	u32 suspend_ctl;
+	u32 *suspend_ch_ctl;
 };
 
 static int img_i2s_out_runtime_suspend(struct device *dev)
@@ -471,6 +473,13 @@ static int img_i2s_out_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	i2s->suspend_ch_ctl = devm_kzalloc(dev,
+		sizeof(*i2s->suspend_ch_ctl) * i2s->max_i2s_chan, GFP_KERNEL);
+	if (!i2s->suspend_ch_ctl) {
+		ret = -ENOMEM;
+		goto err_clk_disable;
+	}
+
 	reg = IMG_I2S_OUT_CTL_FRM_SIZE_MASK;
 	img_i2s_out_writel(i2s, reg, IMG_I2S_OUT_CTL);
 
@@ -520,6 +529,7 @@ err_suspend:
 		img_i2s_out_runtime_suspend(&pdev->dev);
 err_pm_disable:
 	pm_runtime_disable(&pdev->dev);
+err_clk_disable:
 	clk_disable_unprepare(i2s->clk_sys);
 
 	return ret;
@@ -538,6 +548,55 @@ static int img_i2s_out_dev_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int img_i2s_out_suspend(struct device *dev)
+{
+	struct img_i2s_out *i2s = dev_get_drvdata(dev);
+	int i, ret;
+	u32 reg;
+
+	if (pm_runtime_status_suspended(dev)) {
+		ret = img_i2s_out_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < i2s->max_i2s_chan; i++) {
+		reg = img_i2s_out_ch_readl(i2s, i, IMG_I2S_OUT_CH_CTL);
+		i2s->suspend_ch_ctl[i] = reg;
+	}
+
+	i2s->suspend_ctl = img_i2s_out_readl(i2s, IMG_I2S_OUT_CTL);
+
+	img_i2s_out_runtime_suspend(dev);
+
+	return 0;
+}
+
+static int img_i2s_out_resume(struct device *dev)
+{
+	struct img_i2s_out *i2s = dev_get_drvdata(dev);
+	int i, ret;
+	u32 reg;
+
+	ret = img_i2s_out_runtime_resume(dev);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < i2s->max_i2s_chan; i++) {
+		reg = i2s->suspend_ch_ctl[i];
+		img_i2s_out_ch_writel(i2s, i, reg, IMG_I2S_OUT_CH_CTL);
+	}
+
+	img_i2s_out_writel(i2s, i2s->suspend_ctl, IMG_I2S_OUT_CTL);
+
+	if (pm_runtime_status_suspended(dev))
+		img_i2s_out_runtime_suspend(dev);
+
+	return 0;
+}
+#endif
+
 static const struct of_device_id img_i2s_out_of_match[] = {
 	{ .compatible = "img,i2s-out" },
 	{}
@@ -547,6 +606,7 @@ MODULE_DEVICE_TABLE(of, img_i2s_out_of_match);
 static const struct dev_pm_ops img_i2s_out_pm_ops = {
 	SET_RUNTIME_PM_OPS(img_i2s_out_runtime_suspend,
 			   img_i2s_out_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(img_i2s_out_suspend, img_i2s_out_resume)
 };
 
 static struct platform_driver img_i2s_out_driver = {