[PATCH 4/6] soundwire: intel: Add basic power management support

[Pierre-Louis Bossart]

Implement suspend/resume capabilities (not runtime_pm for now)

Credits: this patch is based on an earlier internal contribution by
Vinod Koul, Sanyog Kale, Shreyas Nc and Hardik Shah.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
 drivers/soundwire/cadence_master.c |  18 ++--
 drivers/soundwire/cadence_master.h |   2 +-
 drivers/soundwire/intel.c          | 128 ++++++++++++++++++++++++++++-
 3 files changed, 140 insertions(+), 8 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index bd58d80ff636..fdf9eec7cde1 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -823,14 +823,17 @@ EXPORT_SYMBOL(sdw_cdns_exit_reset);
  * sdw_cdns_enable_interrupt() - Enable SDW interrupts and update config
  * @cdns: Cadence instance
  */
-int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns)
+int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns, bool state)
 {
-	u32 mask;
+	u32 slave_intmask0 = 0;
+	u32 slave_intmask1 = 0;
+	u32 mask = 0;
+
+	if (!state)
+		goto update_masks;
 
-	cdns_writel(cdns, CDNS_MCP_SLAVE_INTMASK0,
-		    CDNS_MCP_SLAVE_INTMASK0_MASK);
-	cdns_writel(cdns, CDNS_MCP_SLAVE_INTMASK1,
-		    CDNS_MCP_SLAVE_INTMASK1_MASK);
+	slave_intmask0 = CDNS_MCP_SLAVE_INTMASK0_MASK;
+	slave_intmask1 = CDNS_MCP_SLAVE_INTMASK1_MASK;
 
 	/* enable detection of all slave state changes */
 	mask = CDNS_MCP_INT_SLAVE_MASK;
@@ -853,6 +856,9 @@ int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns)
 	if (interrupt_mask) /* parameter override */
 		mask = interrupt_mask;
 
+update_masks:
+	cdns_writel(cdns, CDNS_MCP_SLAVE_INTMASK0, slave_intmask0);
+	cdns_writel(cdns, CDNS_MCP_SLAVE_INTMASK1, slave_intmask1);
 	cdns_writel(cdns, CDNS_MCP_INTMASK, mask);
 
 	/* commit changes */
diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
index 1a67728c5000..302351808098 100644
--- a/drivers/soundwire/cadence_master.h
+++ b/drivers/soundwire/cadence_master.h
@@ -162,7 +162,7 @@ int sdw_cdns_init(struct sdw_cdns *cdns);
 int sdw_cdns_pdi_init(struct sdw_cdns *cdns,
 		      struct sdw_cdns_stream_config config);
 int sdw_cdns_exit_reset(struct sdw_cdns *cdns);
-int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns);
+int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns, bool state);
 
 #ifdef CONFIG_DEBUG_FS
 void sdw_cdns_debugfs_init(struct sdw_cdns *cdns, struct dentry *root);
diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 3d22c9023a9b..42bdc870c3ee 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -12,6 +12,7 @@
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <sound/pcm_params.h>
+#include <linux/pm_runtime.h>
 #include <sound/soc.h>
 #include <linux/soundwire/sdw_registers.h>
 #include <linux/soundwire/sdw.h>
@@ -284,6 +285,35 @@ static void intel_debugfs_exit(struct sdw_intel *sdw) {}
 /*
  * shim ops
  */
+static int intel_link_power_down(struct sdw_intel *sdw)
+{
+	int link_control, spa_mask, cpa_mask, ret;
+	unsigned int link_id = sdw->instance;
+	void __iomem *shim = sdw->res->shim;
+	u16 ioctl;
+
+	/* Glue logic */
+	ioctl = intel_readw(shim, SDW_SHIM_IOCTL(link_id));
+	ioctl |= SDW_SHIM_IOCTL_BKE;
+	ioctl |= SDW_SHIM_IOCTL_COE;
+	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+
+	ioctl &= ~(SDW_SHIM_IOCTL_MIF);
+	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+
+	/* Link power down sequence */
+	link_control = intel_readl(shim, SDW_SHIM_LCTL);
+	spa_mask = ~(SDW_SHIM_LCTL_SPA << link_id);
+	cpa_mask = (SDW_SHIM_LCTL_CPA << link_id);
+	link_control &=  spa_mask;
+
+	ret = intel_clear_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
+	if (ret < 0)
+		return ret;
+
+	sdw->cdns.link_up = false;
+	return 0;
+}
 
 static int intel_link_power_up(struct sdw_intel *sdw)
 {
@@ -306,6 +336,29 @@ static int intel_link_power_up(struct sdw_intel *sdw)
 	return 0;
 }
 
+static void intel_shim_wake(struct sdw_intel *sdw, bool wake_enable)
+{
+	void __iomem *shim = sdw->res->shim;
+	unsigned int link_id = sdw->instance;
+	u16 wake_en, wake_sts;
+
+	if (wake_enable) {
+		/* Enable the wakeup */
+		intel_writew(shim, SDW_SHIM_WAKEEN,
+			     (SDW_SHIM_WAKEEN_ENABLE << link_id));
+	} else {
+		/* Disable the wake up interrupt */
+		wake_en = intel_readw(shim, SDW_SHIM_WAKEEN);
+		wake_en &= ~(SDW_SHIM_WAKEEN_ENABLE << link_id);
+		intel_writew(shim, SDW_SHIM_WAKEEN, wake_en);
+
+		/* Clear wake status */
+		wake_sts = intel_readw(shim, SDW_SHIM_WAKESTS);
+		wake_sts |= (SDW_SHIM_WAKEEN_ENABLE << link_id);
+		intel_writew(shim, SDW_SHIM_WAKESTS_STATUS, wake_sts);
+	}
+}
+
 static int intel_shim_init(struct sdw_intel *sdw)
 {
 	void __iomem *shim = sdw->res->shim;
@@ -1066,7 +1119,7 @@ static int intel_probe(struct platform_device *pdev)
 		goto err_init;
 	}
 
-	ret = sdw_cdns_enable_interrupt(&sdw->cdns);
+	ret = sdw_cdns_enable_interrupt(&sdw->cdns, true);
 	if (ret < 0) {
 		dev_err(sdw->cdns.dev, "cannot enable interrupts\n");
 		goto err_init;
@@ -1114,11 +1167,84 @@ static int intel_remove(struct platform_device *pdev)
 	return 0;
 }
 
+/*
+ * PM calls
+ */
+
+#ifdef CONFIG_PM
+
+static int intel_suspend(struct device *dev)
+{
+	struct sdw_intel *sdw = dev_get_drvdata(dev);
+	int ret;
+
+	if (sdw->cdns.bus.prop.hw_disabled) {
+		dev_dbg(dev, "SoundWire master %d is disabled, ignoring\n",
+			sdw->cdns.bus.link_id);
+		return 0;
+	}
+
+	ret = sdw_cdns_enable_interrupt(&sdw->cdns, false);
+	if (ret < 0) {
+		dev_err(sdw->cdns.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_intel *sdw = dev_get_drvdata(dev);
+	int ret;
+
+	if (sdw->cdns.bus.prop.hw_disabled) {
+		dev_dbg(dev, "SoundWire master %d is disabled, ignoring\n",
+			sdw->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(&sdw->cdns, true);
+	if (ret < 0) {
+		dev_err(sdw->cdns.dev, "cannot enable interrupts during resume\n");
+		return ret;
+	}
+
+	ret = sdw_cdns_exit_reset(&sdw->cdns);
+	if (ret < 0) {
+		dev_err(sdw->cdns.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)
+};
+
 static struct platform_driver sdw_intel_drv = {
 	.probe = intel_probe,
 	.remove = intel_remove,
 	.driver = {
 		.name = "int-sdw",
+		.pm = &intel_pm,
 
 	},
 };
-- 
2.20.1