[RFC PATCH 33/40] 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/intel.c | 102 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 215dc81cdf73..1477c35f616f 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>
@@ -278,6 +279,35 @@ 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)
 {
@@ -300,6 +330,29 @@ 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;
@@ -1095,11 +1148,60 @@ 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;
+	int ret;
+
+	sdw = dev_get_drvdata(dev);
+
+	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;
+	int ret;
+
+	sdw = dev_get_drvdata(dev);
+
+	ret = intel_init(sdw);
+	if (ret) {
+		dev_err(dev, "%s failed: %d", __func__, ret);
+		return ret;
+	}
+
+	sdw_cdns_enable_interrupt(&sdw->cdns);
+
+	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