ASoC: davinci-mcasp: add support for suspend and resume

When the system returns from suspend, it looses its configuration. Most
of it is restored by running a normal audio stream startup, but the DAI
format is left unset as that's configured on the audio device creation.

Hence, it suffices here to care for the registers which are touched by
davinci_mcasp_set_dai_fmt() and restore them when the system is resumed.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/davinci/davinci-mcasp.c

@@ -1251,12 +1251,51 @@ static int davinci_mcasp_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int davinci_mcasp_suspend(struct device *dev)
+{
+	struct davinci_audio_dev *a = dev_get_drvdata(dev);
+	void __iomem *base = a->base;
+
+	a->context.txfmtctl = mcasp_get_reg(base + DAVINCI_MCASP_TXFMCTL_REG);
+	a->context.rxfmtctl = mcasp_get_reg(base + DAVINCI_MCASP_RXFMCTL_REG);
+	a->context.txfmt = mcasp_get_reg(base + DAVINCI_MCASP_TXFMT_REG);
+	a->context.rxfmt = mcasp_get_reg(base + DAVINCI_MCASP_RXFMT_REG);
+	a->context.aclkxctl = mcasp_get_reg(base + DAVINCI_MCASP_ACLKXCTL_REG);
+	a->context.aclkrctl = mcasp_get_reg(base + DAVINCI_MCASP_ACLKRCTL_REG);
+	a->context.pdir = mcasp_get_reg(base + DAVINCI_MCASP_PDIR_REG);
+
+	return 0;
+}
+
+static int davinci_mcasp_resume(struct device *dev)
+{
+	struct davinci_audio_dev *a = dev_get_drvdata(dev);
+	void __iomem *base = a->base;
+
+	mcasp_set_reg(base + DAVINCI_MCASP_TXFMCTL_REG, a->context.txfmtctl);
+	mcasp_set_reg(base + DAVINCI_MCASP_RXFMCTL_REG, a->context.rxfmtctl);
+	mcasp_set_reg(base + DAVINCI_MCASP_TXFMT_REG, a->context.txfmt);
+	mcasp_set_reg(base + DAVINCI_MCASP_RXFMT_REG, a->context.rxfmt);
+	mcasp_set_reg(base + DAVINCI_MCASP_ACLKXCTL_REG, a->context.aclkxctl);
+	mcasp_set_reg(base + DAVINCI_MCASP_ACLKRCTL_REG, a->context.aclkrctl);
+	mcasp_set_reg(base + DAVINCI_MCASP_PDIR_REG, a->context.pdir);
+
+	return 0;
+}
+#endif
+
+SIMPLE_DEV_PM_OPS(davinci_mcasp_pm_ops,
+		  davinci_mcasp_suspend,
+		  davinci_mcasp_resume);
+
 static struct platform_driver davinci_mcasp_driver = {
 	.probe		= davinci_mcasp_probe,
 	.remove		= davinci_mcasp_remove,
 	.driver		= {
 		.name	= "davinci-mcasp",
 		.owner	= THIS_MODULE,
+		.pm	= &davinci_mcasp_pm_ops,
 		.of_match_table = mcasp_dt_ids,
 	},
 };

sound/soc/davinci/davinci-mcasp.h

@@ -43,6 +43,18 @@ struct davinci_audio_dev {
 	/* McASP FIFO related */
 	u8	txnumevt;
 	u8	rxnumevt;
+
+#ifdef CONFIG_PM_SLEEP
+	struct {
+		u32	txfmtctl;
+		u32	rxfmtctl;
+		u32	txfmt;
+		u32	rxfmt;
+		u32	aclkxctl;
+		u32	aclkrctl;
+		u32	pdir;
+	} context;
+#endif
 };
 
 #endif	/* DAVINCI_MCASP_H */