ASoC: img-i2s-in: 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-in.c

@@ -60,6 +60,8 @@ struct img_i2s_in {
 	void __iomem *channel_base;
 	unsigned int active_channels;
 	struct snd_soc_dai_driver dai_driver;
+	u32 suspend_ctl;
+	u32 *suspend_ch_ctl;
 };
 
 static inline void img_i2s_in_writel(struct img_i2s_in *i2s, u32 val, u32 reg)
@@ -469,6 +471,13 @@ static int img_i2s_in_probe(struct platform_device *pdev)
 			IMG_I2S_IN_CH_CTL_JUST_MASK |
 			IMG_I2S_IN_CH_CTL_FW_MASK, IMG_I2S_IN_CH_CTL);
 
+	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;
+	}
+
 	ret = devm_snd_soc_register_component(dev, &img_i2s_in_component,
 						&i2s->dai_driver, 1);
 	if (ret)
@@ -495,16 +504,59 @@ static int img_i2s_in_dev_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int img_i2s_in_suspend(struct device *dev)
+{
+	struct img_i2s_in *i2s = dev_get_drvdata(dev);
+	int i;
+	u32 reg;
+
+	for (i = 0; i < i2s->max_i2s_chan; i++) {
+		reg = img_i2s_in_ch_readl(i2s, i, IMG_I2S_IN_CH_CTL);
+		i2s->suspend_ch_ctl[i] = reg;
+	}
+
+	i2s->suspend_ctl = img_i2s_in_readl(i2s, IMG_I2S_IN_CTL);
+
+	clk_disable_unprepare(i2s->clk_sys);
+
+	return 0;
+}
+
+static int img_i2s_in_resume(struct device *dev)
+{
+	struct img_i2s_in *i2s = dev_get_drvdata(dev);
+	int i;
+	u32 reg;
+
+	clk_prepare_enable(i2s->clk_sys);
+
+	for (i = 0; i < i2s->max_i2s_chan; i++) {
+		reg = i2s->suspend_ch_ctl[i];
+		img_i2s_in_ch_writel(i2s, i, reg, IMG_I2S_IN_CH_CTL);
+	}
+
+	img_i2s_in_writel(i2s, i2s->suspend_ctl, IMG_I2S_IN_CTL);
+
+	return 0;
+}
+#endif
+
 static const struct of_device_id img_i2s_in_of_match[] = {
 	{ .compatible = "img,i2s-in" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, img_i2s_in_of_match);
 
+static const struct dev_pm_ops img_i2s_in_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(img_i2s_in_suspend, img_i2s_in_resume)
+};
+
 static struct platform_driver img_i2s_in_driver = {
 	.driver = {
 		.name = "img-i2s-in",
-		.of_match_table = img_i2s_in_of_match
+		.of_match_table = img_i2s_in_of_match,
+		.pm = &img_i2s_in_pm_ops
 	},
 	.probe = img_i2s_in_probe,
 	.remove = img_i2s_in_dev_remove