linux-kernel - [PATCH 09/13] soundwire: intel: add CLK_STOP_BUS

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Date:   Wed, 22 Jul 2020 04:37:19 +0800
From:   Bard Liao <yung-chuan.liao@...ux.intel.com>
To:     alsa-devel@...a-project.org, vkoul@...nel.org
Cc:     vinod.koul@...aro.org, linux-kernel@...r.kernel.org, tiwai@...e.de,
        broonie@...nel.org, gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, rander.wang@...ux.intel.com,
        ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
        pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
        slawomir.blauciak@...el.com, mengdong.lin@...el.com,
        bard.liao@...el.com
Subject: [PATCH 09/13] soundwire: intel: add CLK_STOP_BUS_RESET support

From: Rander Wang <rander.wang@...el.com>

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@...el.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
---
 drivers/soundwire/intel.c | 44 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 1954eb48b86c..744fc0a4816a 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -1576,6 +1576,26 @@ 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);
@@ -1694,6 +1714,30 @@ 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);
-- 
2.17.1