soundwire: intel: revisit SHIM programming sequences.

Somehow the existing code is not aligned with the steps described in
the documentation, refactor code and make sure the register
programming sequences are correct. Also add missing power-up,
power-down and wake capabilities (the last two are used in follow-up
patches but introduced here for consistency).

Some of the SHIM registers exposed fields that are link specific, and
in addition some of the power-related registers (SPA/CPA) take time to
be updated. Uncontrolled access leads to timeouts or errors. Add a
mutex, shared by all links, so that all accesses to such registers are
serialized, and follow a pattern of read-modify-write.

This includes making sure SHIM_SYNC is programmed only once, before
the first master is powered on. We use a 'shim_mask' field, shared
between all links and protected by a mutex, to deal with power-up and
power-down sequences.

Note that the SYNCPRD value is tied only to the XTAL value and not the
current bus frequency or the frame rate.

BugLink: https://github.com/thesofproject/linux/issues/1555Signed-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/20200716150947.22119-3-yung-chuan.liao@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/intel.c

@@ -46,7 +46,8 @@
 #define SDW_SHIM_LCTL_SPA		BIT(0)
 #define SDW_SHIM_LCTL_CPA		BIT(8)
 
-#define SDW_SHIM_SYNC_SYNCPRD_VAL	0x176F
+#define SDW_SHIM_SYNC_SYNCPRD_VAL_24	(24000 / SDW_CADENCE_GSYNC_KHZ - 1)
+#define SDW_SHIM_SYNC_SYNCPRD_VAL_38_4	(38400 / SDW_CADENCE_GSYNC_KHZ - 1)
 #define SDW_SHIM_SYNC_SYNCPRD		GENMASK(14, 0)
 #define SDW_SHIM_SYNC_SYNCCPU		BIT(15)
 #define SDW_SHIM_SYNC_CMDSYNC_MASK	GENMASK(19, 16)
@@ -272,8 +273,46 @@ static int intel_link_power_up(struct sdw_intel *sdw)
 {
 	unsigned int link_id = sdw->instance;
 	void __iomem *shim = sdw->link_res->shim;
+	u32 *shim_mask = sdw->link_res->shim_mask;
+	struct sdw_bus *bus = &sdw->cdns.bus;
+	struct sdw_master_prop *prop = &bus->prop;
 	int spa_mask, cpa_mask;
-	int link_control, ret;
+	int link_control;
+	int ret = 0;
+	u32 syncprd;
+	u32 sync_reg;
+
+	mutex_lock(sdw->link_res->shim_lock);
+
+	/*
+	 * The hardware relies on an internal counter, typically 4kHz,
+	 * to generate the SoundWire SSP - which defines a 'safe'
+	 * synchronization point between commands and audio transport
+	 * and allows for multi link synchronization. The SYNCPRD value
+	 * is only dependent on the oscillator clock provided to
+	 * the IP, so adjust based on _DSD properties reported in DSDT
+	 * tables. The values reported are based on either 24MHz
+	 * (CNL/CML) or 38.4 MHz (ICL/TGL+).
+	 */
+	if (prop->mclk_freq % 6000000)
+		syncprd = SDW_SHIM_SYNC_SYNCPRD_VAL_38_4;
+	else
+		syncprd = SDW_SHIM_SYNC_SYNCPRD_VAL_24;
+
+	if (!*shim_mask) {
+		/* we first need to program the SyncPRD/CPU registers */
+		dev_dbg(sdw->cdns.dev,
+			"%s: first link up, programming SYNCPRD\n", __func__);
+
+		/* set SyncPRD period */
+		sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
+		sync_reg |= (syncprd <<
+			     SDW_REG_SHIFT(SDW_SHIM_SYNC_SYNCPRD));
+
+		/* Set SyncCPU bit */
+		sync_reg |= SDW_SHIM_SYNC_SYNCCPU;
+		intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
+	}
 
 	/* Link power up sequence */
 	link_control = intel_readl(shim, SDW_SHIM_LCTL);
@@ -282,68 +321,180 @@ static int intel_link_power_up(struct sdw_intel *sdw)
 	link_control |=  spa_mask;
 
 	ret = intel_set_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
-	if (ret < 0)
-		return ret;
+	if (ret < 0) {
+		dev_err(sdw->cdns.dev, "Failed to power up link: %d\n", ret);
+		goto out;
+	}
+
+	if (!*shim_mask) {
+		/* SyncCPU will change once link is active */
+		ret = intel_wait_bit(shim, SDW_SHIM_SYNC,
+				     SDW_SHIM_SYNC_SYNCCPU, 0);
+		if (ret < 0) {
+			dev_err(sdw->cdns.dev,
+				"Failed to set SHIM_SYNC: %d\n", ret);
+			goto out;
+		}
+	}
+
+	*shim_mask |= BIT(link_id);
 
 	sdw->cdns.link_up = true;
-	return 0;
+out:
+	mutex_unlock(sdw->link_res->shim_lock);
+
+	return ret;
 }
 
-static int intel_shim_init(struct sdw_intel *sdw)
+/* this needs to be called with shim_lock */
+static void intel_shim_glue_to_master_ip(struct sdw_intel *sdw)
 {
 	void __iomem *shim = sdw->link_res->shim;
 	unsigned int link_id = sdw->instance;
-	int sync_reg, ret;
-	u16 ioctl = 0, act = 0;
+	u16 ioctl;
 
-	/* Initialize Shim */
-	ioctl |= SDW_SHIM_IOCTL_BKE;
+	/* Switch to MIP from Glue logic */
+	ioctl = intel_readw(shim,  SDW_SHIM_IOCTL(link_id));
+
+	ioctl &= ~(SDW_SHIM_IOCTL_DOE);
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
-	ioctl |= SDW_SHIM_IOCTL_WPDD;
+	ioctl &= ~(SDW_SHIM_IOCTL_DO);
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
-	ioctl |= SDW_SHIM_IOCTL_DO;
+	ioctl |= (SDW_SHIM_IOCTL_MIF);
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
-	ioctl |= SDW_SHIM_IOCTL_DOE;
+	ioctl &= ~(SDW_SHIM_IOCTL_BKE);
+	ioctl &= ~(SDW_SHIM_IOCTL_COE);
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
-	/* Switch to MIP from Glue logic */
-	ioctl = intel_readw(shim,  SDW_SHIM_IOCTL(link_id));
+	/* at this point Master IP has full control of the I/Os */
+}
 
-	ioctl &= ~(SDW_SHIM_IOCTL_DOE);
+/* this needs to be called with shim_lock */
+static void intel_shim_master_ip_to_glue(struct sdw_intel *sdw)
+{
+	unsigned int link_id = sdw->instance;
+	void __iomem *shim = sdw->link_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);
+	usleep_range(10, 15);
 
-	ioctl &= ~(SDW_SHIM_IOCTL_DO);
+	ioctl &= ~(SDW_SHIM_IOCTL_MIF);
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
-	ioctl |= (SDW_SHIM_IOCTL_MIF);
+	/* at this point Integration Glue has full control of the I/Os */
+}
+
+static int intel_shim_init(struct sdw_intel *sdw, bool clock_stop)
+{
+	void __iomem *shim = sdw->link_res->shim;
+	unsigned int link_id = sdw->instance;
+	int ret = 0;
+	u16 ioctl = 0, act = 0;
+
+	mutex_lock(sdw->link_res->shim_lock);
+
+	/* Initialize Shim */
+	ioctl |= SDW_SHIM_IOCTL_BKE;
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
-	ioctl &= ~(SDW_SHIM_IOCTL_BKE);
-	ioctl &= ~(SDW_SHIM_IOCTL_COE);
+	ioctl |= SDW_SHIM_IOCTL_WPDD;
+	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
 
+	ioctl |= SDW_SHIM_IOCTL_DO;
+	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
+
+	ioctl |= SDW_SHIM_IOCTL_DOE;
 	intel_writew(shim, SDW_SHIM_IOCTL(link_id), ioctl);
+	usleep_range(10, 15);
+
+	intel_shim_glue_to_master_ip(sdw);
 
 	act |= 0x1 << SDW_REG_SHIFT(SDW_SHIM_CTMCTL_DOAIS);
 	act |= SDW_SHIM_CTMCTL_DACTQE;
 	act |= SDW_SHIM_CTMCTL_DODS;
 	intel_writew(shim, SDW_SHIM_CTMCTL(link_id), act);
+	usleep_range(10, 15);
 
-	/* Now set SyncPRD period */
-	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
-	sync_reg |= (SDW_SHIM_SYNC_SYNCPRD_VAL <<
-			SDW_REG_SHIFT(SDW_SHIM_SYNC_SYNCPRD));
+	mutex_unlock(sdw->link_res->shim_lock);
+
+	return ret;
+}
+
+static void __maybe_unused intel_shim_wake(struct sdw_intel *sdw, bool wake_enable)
+{
+	void __iomem *shim = sdw->link_res->shim;
+	unsigned int link_id = sdw->instance;
+	u16 wake_en, wake_sts;
+
+	mutex_lock(sdw->link_res->shim_lock);
+	wake_en = intel_readw(shim, SDW_SHIM_WAKEEN);
+
+	if (wake_enable) {
+		/* Enable the wakeup */
+		wake_en |= (SDW_SHIM_WAKEEN_ENABLE << link_id);
+		intel_writew(shim, SDW_SHIM_WAKEEN, wake_en);
+	} else {
+		/* Disable the wake up interrupt */
+		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);
+	}
+	mutex_unlock(sdw->link_res->shim_lock);
+}
+
+static int __maybe_unused intel_link_power_down(struct sdw_intel *sdw)
+{
+	int link_control, spa_mask, cpa_mask;
+	unsigned int link_id = sdw->instance;
+	void __iomem *shim = sdw->link_res->shim;
+	u32 *shim_mask = sdw->link_res->shim_mask;
+	int ret = 0;
+
+	mutex_lock(sdw->link_res->shim_lock);
+
+	intel_shim_master_ip_to_glue(sdw);
+
+	/* 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 (!(*shim_mask & BIT(link_id)))
+		dev_err(sdw->cdns.dev,
+			"%s: Unbalanced power-up/down calls\n", __func__);
+
+	*shim_mask &= ~BIT(link_id);
+
+	mutex_unlock(sdw->link_res->shim_lock);
 
-	/* Set SyncCPU bit */
-	sync_reg |= SDW_SHIM_SYNC_SYNCCPU;
-	ret = intel_clear_bit(shim, SDW_SHIM_SYNC, sync_reg,
-			      SDW_SHIM_SYNC_SYNCCPU);
 	if (ret < 0)
-		dev_err(sdw->cdns.dev, "Failed to set sync period: %d\n", ret);
+		return ret;
 
-	return ret;
+	sdw->cdns.link_up = false;
+	return 0;
 }
 
 /*
@@ -566,11 +717,15 @@ static int intel_pre_bank_switch(struct sdw_bus *bus)
 	if (!bus->multi_link)
 		return 0;
 
+	mutex_lock(sdw->link_res->shim_lock);
+
 	/* Read SYNC register */
 	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
 	sync_reg |= SDW_SHIM_SYNC_CMDSYNC << sdw->instance;
 	intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
 
+	mutex_unlock(sdw->link_res->shim_lock);
+
 	return 0;
 }
 
@@ -585,6 +740,8 @@ static int intel_post_bank_switch(struct sdw_bus *bus)
 	if (!bus->multi_link)
 		return 0;
 
+	mutex_lock(sdw->link_res->shim_lock);
+
 	/* Read SYNC register */
 	sync_reg = intel_readl(shim, SDW_SHIM_SYNC);
 
@@ -596,9 +753,10 @@ static int intel_post_bank_switch(struct sdw_bus *bus)
 	 *
 	 * So, set the SYNCGO bit only if CMDSYNC bit is set for any Master.
 	 */
-	if (!(sync_reg & SDW_SHIM_SYNC_CMDSYNC_MASK))
-		return 0;
-
+	if (!(sync_reg & SDW_SHIM_SYNC_CMDSYNC_MASK)) {
+		ret = 0;
+		goto unlock;
+	}
 	/*
 	 * Set SyncGO bit to synchronously trigger a bank switch for
 	 * all the masters. A write to SYNCGO bit clears CMDSYNC bit for all
@@ -608,6 +766,9 @@ static int intel_post_bank_switch(struct sdw_bus *bus)
 
 	ret = intel_clear_bit(shim, SDW_SHIM_SYNC, sync_reg,
 			      SDW_SHIM_SYNC_SYNCGO);
+unlock:
+	mutex_unlock(sdw->link_res->shim_lock);
+
 	if (ret < 0)
 		dev_err(sdw->cdns.dev, "Post bank switch failed: %d\n", ret);
 
@@ -1011,9 +1172,17 @@ static struct sdw_master_ops sdw_intel_ops = {
 
 static int intel_init(struct sdw_intel *sdw)
 {
+	bool clock_stop;
+
 	/* Initialize shim and controller */
 	intel_link_power_up(sdw);
-	intel_shim_init(sdw);
+
+	clock_stop = sdw_cdns_is_clock_stop(&sdw->cdns);
+
+	intel_shim_init(sdw, clock_stop);
+
+	if (clock_stop)
+		return 0;
 
 	return sdw_cdns_init(&sdw->cdns);
 }

drivers/soundwire/intel.h

@@ -15,6 +15,8 @@
  * @irq: Interrupt line
  * @ops: Shim callback ops
  * @dev: device implementing hw_params and free callbacks
+ * @shim_lock: mutex to handle access to shared SHIM registers
+ * @shim_mask: global pointer to check SHIM register initialization
  */
 struct sdw_intel_link_res {
 	struct platform_device *pdev;
@@ -25,6 +27,8 @@ struct sdw_intel_link_res {
 	int irq;
 	const struct sdw_intel_ops *ops;
 	struct device *dev;
+	struct mutex *shim_lock; /* protect shared registers */
+	u32 *shim_mask;
 };
 
 struct sdw_intel {

drivers/soundwire/intel_init.c

@@ -180,6 +180,7 @@ static struct sdw_intel_ctx
 	ctx->mmio_base = res->mmio_base;
 	ctx->link_mask = res->link_mask;
 	ctx->handle = res->handle;
+	mutex_init(&ctx->shim_lock);
 
 	link = ctx->links;
 	link_mask = ctx->link_mask;
@@ -201,6 +202,9 @@ static struct sdw_intel_ctx
 		link->ops = res->ops;
 		link->dev = res->dev;
 
+		link->shim_lock = &ctx->shim_lock;
+		link->shim_mask = &ctx->shim_mask;
+
 		memset(&pdevinfo, 0, sizeof(pdevinfo));
 
 		pdevinfo.parent = res->parent;

include/linux/soundwire/sdw_intel.h

@@ -115,6 +115,7 @@ struct sdw_intel_slave_id {
  * links
  * @link_list: list to handle interrupts across all links
  * @shim_lock: mutex to handle concurrent rmw access to shared SHIM registers.
+ * @shim_mask: flags to track initialization of SHIM shared registers
  */
 struct sdw_intel_ctx {
 	int count;
@@ -126,6 +127,7 @@ struct sdw_intel_ctx {
 	struct sdw_intel_slave_id *ids;
 	struct list_head link_list;
 	struct mutex shim_lock; /* lock for access to shared SHIM registers */
+	u32 shim_mask;
 };
 
 /**