soundwire: intel: add CLK_STOP_BUS_RESET support

Move existing pm_runtime suspend under the CLK_STOP_TEARDOWN case.

In this mode the Master IP will lose all context but in-band wakes are
supported.

On pm_runtime resume a complete re-enumeration will be performed after
a bus reset.
Signed-off-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200817152923.3259-9-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/intel.c

@@ -1575,6 +1575,26 @@ static int intel_suspend_runtime(struct device *dev)
 
 		intel_shim_wake(sdw, false);
 
+	} else if (clock_stop_quirks & SDW_INTEL_CLK_STOP_BUS_RESET) {
+		ret = sdw_cdns_clock_stop(cdns, true);
+		if (ret < 0) {
+			dev_err(dev, "cannot enable clock stop on suspend\n");
+			return ret;
+		}
+
+		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, true);
 	} else {
 		dev_err(dev, "%s clock_stop_quirks %x unsupported\n",
 			__func__, clock_stop_quirks);
@@ -1691,6 +1711,30 @@ static int intel_resume_runtime(struct device *dev)
 			dev_err(dev, "unable to exit bus reset sequence during resume\n");
 			return ret;
 		}
+	} else if (clock_stop_quirks & SDW_INTEL_CLK_STOP_BUS_RESET) {
+		ret = intel_init(sdw);
+		if (ret) {
+			dev_err(dev, "%s failed: %d", __func__, ret);
+			return ret;
+		}
+
+		/*
+		 * make sure all Slaves are tagged as UNATTACHED and
+		 * provide reason for reinitialization
+		 */
+		sdw_clear_slave_status(bus, SDW_UNATTACH_REQUEST_MASTER_RESET);
+
+		ret = sdw_cdns_enable_interrupt(cdns, true);
+		if (ret < 0) {
+			dev_err(dev, "cannot enable interrupts during resume\n");
+			return ret;
+		}
+
+		ret = sdw_cdns_clock_restart(cdns, true);
+		if (ret < 0) {
+			dev_err(dev, "unable to restart clock during resume\n");
+			return ret;
+		}
 	} else {
 		dev_err(dev, "%s clock_stop_quirks %x unsupported\n",
 			__func__, clock_stop_quirks);