[alsa-devel] [PATCH 06/18] soundwire: intel: Add basic power management support

[Pierre-Louis Bossart]

Implement suspend/resume capabilities (not runtime_pm for now)
The resume part is essentially a full-blown re-enumeration.

When S0ix is supported, we will select clock stop mode when the ACPI
target state is S0, and tear down the link for S3.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 drivers/soundwire/intel.c | 75 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index fe3a8b3b2c04..aeef0c0fc443 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -1253,10 +1253,85 @@ static int intel_master_remove(struct sdw_master_device *md)
 	return 0;
 }
 
+/*
+ * PM calls
+ */
+
+#ifdef CONFIG_PM
+
+static int intel_suspend(struct device *dev)
+{
+	struct sdw_cdns *cdns = dev_get_drvdata(dev);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
+	int ret;
+
+	if (cdns->bus.prop.hw_disabled) {
+		dev_dbg(dev, "SoundWire master %d is disabled, ignoring\n",
+			cdns->bus.link_id);
+		return 0;
+	}
+
+	ret = sdw_cdns_enable_interrupt(cdns, false);
+	if (ret < 0) {
+		dev_err(dev, "cannot disable interrupts on suspend\n");
+		return ret;
+	}
+
+	ret = intel_link_power_down(sdw);
+	if (ret) {
+		dev_err(dev, "Link power down failed: %d", ret);
+		return ret;
+	}
+
+	intel_shim_wake(sdw, false);
+
+	return 0;
+}
+
+static int intel_resume(struct device *dev)
+{
+	struct sdw_cdns *cdns = dev_get_drvdata(dev);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
+	int ret;
+
+	if (cdns->bus.prop.hw_disabled) {
+		dev_dbg(dev, "SoundWire master %d is disabled, ignoring\n",
+			cdns->bus.link_id);
+		return 0;
+	}
+
+	ret = intel_init(sdw);
+	if (ret) {
+		dev_err(dev, "%s failed: %d", __func__, ret);
+		return ret;
+	}
+
+	ret = sdw_cdns_enable_interrupt(cdns, true);
+	if (ret < 0) {
+		dev_err(dev, "cannot enable interrupts during resume\n");
+		return ret;
+	}
+
+	ret = sdw_cdns_exit_reset(cdns);
+	if (ret < 0) {
+		dev_err(dev, "unable to exit bus reset sequence during resume\n");
+		return ret;
+	}
+
+	return ret;
+}
+
+#endif
+
+static const struct dev_pm_ops intel_pm = {
+	SET_SYSTEM_SLEEP_PM_OPS(intel_suspend, intel_resume)
+};
+
 struct sdw_md_driver intel_sdw_driver = {
 	.driver = {
 		.name = "intel-sdw",
 		.owner = THIS_MODULE,
+		.pm = &intel_pm,
 	},
 	.probe = intel_master_probe,
 	.startup = intel_master_startup,
-- 
2.20.1