dmaengine: idxd: add work queue drain support

Add wq drain support. When a wq is being released, it needs to wait for
all in-flight operation to complete.  A device control function
idxd_wq_drain() has been added to facilitate this. A wq drain call
is added to the char dev on release to make sure all user operations are
complete. A wq drain is also added before the wq is being disabled.

A drain command can take an unpredictable period of time. Interrupt support
for device commands is added to allow waiting on the command to
finish. If a previous command is in progress, the new submitter can block
until the current command is finished before proceeding. The interrupt
based submission will submit the command and then wait until a command
completion interrupt happens to complete. All commands are moved to the
interrupt based command submission except for the device reset during
probe, which will be polled.

Fixes: 42d279f9137a ("dmaengine: idxd: add char driver to expose submission portal to userland")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/159319502515.69593.13451647706946040301.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 70 insertions, 85 deletions

diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 8f05b29e7891..1d8d64508a28 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -11,8 +11,8 @@
 #include "idxd.h"
 #include "registers.h"
 
-static int idxd_cmd_wait(struct idxd_device *idxd, u32 *status, int timeout);
-static int idxd_cmd_send(struct idxd_device *idxd, int cmd_code, u32 operand);
+static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
+			  u32 *status);
 
 /* Interrupt control bits */
 int idxd_mask_msix_vector(struct idxd_device *idxd, int vec_id)
@@ -233,21 +233,13 @@ int idxd_wq_enable(struct idxd_wq *wq)
 	struct idxd_device *idxd = wq->idxd;
 	struct device *dev = &idxd->pdev->dev;
 	u32 status;
-	int rc;
-
-	lockdep_assert_held(&idxd->dev_lock);
 
 	if (wq->state == IDXD_WQ_ENABLED) {
 		dev_dbg(dev, "WQ %d already enabled\n", wq->id);
 		return -ENXIO;
 	}
 
-	rc = idxd_cmd_send(idxd, IDXD_CMD_ENABLE_WQ, wq->id);
-	if (rc < 0)
-		return rc;
-	rc = idxd_cmd_wait(idxd, &status, IDXD_REG_TIMEOUT);
-	if (rc < 0)
-		return rc;
+	idxd_cmd_exec(idxd, IDXD_CMD_ENABLE_WQ, wq->id, &status);
 
 	if (status != IDXD_CMDSTS_SUCCESS &&
 	    status != IDXD_CMDSTS_ERR_WQ_ENABLED) {
@@ -265,9 +257,7 @@ int idxd_wq_disable(struct idxd_wq *wq)
 	struct idxd_device *idxd = wq->idxd;
 	struct device *dev = &idxd->pdev->dev;
 	u32 status, operand;
-	int rc;
 
-	lockdep_assert_held(&idxd->dev_lock);
 	dev_dbg(dev, "Disabling WQ %d\n", wq->id);
 
 	if (wq->state != IDXD_WQ_ENABLED) {
@@ -276,12 +266,7 @@ int idxd_wq_disable(struct idxd_wq *wq)
 	}
 
 	operand = BIT(wq->id % 16) | ((wq->id / 16) << 16);
-	rc = idxd_cmd_send(idxd, IDXD_CMD_DISABLE_WQ, operand);
-	if (rc < 0)
-		return rc;
-	rc = idxd_cmd_wait(idxd, &status, IDXD_REG_TIMEOUT);
-	if (rc < 0)
-		return rc;
+	idxd_cmd_exec(idxd, IDXD_CMD_DISABLE_WQ, operand, &status);
 
 	if (status != IDXD_CMDSTS_SUCCESS) {
 		dev_dbg(dev, "WQ disable failed: %#x\n", status);
@@ -293,6 +278,22 @@ int idxd_wq_disable(struct idxd_wq *wq)
 	return 0;
 }
 
+void idxd_wq_drain(struct idxd_wq *wq)
+{
+	struct idxd_device *idxd = wq->idxd;
+	struct device *dev = &idxd->pdev->dev;
+	u32 operand;
+
+	if (wq->state != IDXD_WQ_ENABLED) {
+		dev_dbg(dev, "WQ %d in wrong state: %d\n", wq->id, wq->state);
+		return;
+	}
+
+	dev_dbg(dev, "Draining WQ %d\n", wq->id);
+	operand = BIT(wq->id % 16) | ((wq->id / 16) << 16);
+	idxd_cmd_exec(idxd, IDXD_CMD_DRAIN_WQ, operand, NULL);
+}
+
 int idxd_wq_map_portal(struct idxd_wq *wq)
 {
 	struct idxd_device *idxd = wq->idxd;
@@ -330,66 +331,79 @@ static inline bool idxd_is_enabled(struct idxd_device *idxd)
 	return false;
 }
 
-static int idxd_cmd_wait(struct idxd_device *idxd, u32 *status, int timeout)
+/*
+ * This is function is only used for reset during probe and will
+ * poll for completion. Once the device is setup with interrupts,
+ * all commands will be done via interrupt completion.
+ */
+void idxd_device_init_reset(struct idxd_device *idxd)
 {
-	u32 sts, to = timeout;
-
-	lockdep_assert_held(&idxd->dev_lock);
-	sts = ioread32(idxd->reg_base + IDXD_CMDSTS_OFFSET);
-	while (sts & IDXD_CMDSTS_ACTIVE && --to) {
-		cpu_relax();
-		sts = ioread32(idxd->reg_base + IDXD_CMDSTS_OFFSET);
-	}
+	struct device *dev = &idxd->pdev->dev;
+	union idxd_command_reg cmd;
+	unsigned long flags;
 
-	if (to == 0 && sts & IDXD_CMDSTS_ACTIVE) {
-		dev_warn(&idxd->pdev->dev, "%s timed out!\n", __func__);
-		*status = 0;
-		return -EBUSY;
-	}
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.cmd = IDXD_CMD_RESET_DEVICE;
+	dev_dbg(dev, "%s: sending reset for init.\n", __func__);
+	spin_lock_irqsave(&idxd->dev_lock, flags);
+	iowrite32(cmd.bits, idxd->reg_base + IDXD_CMD_OFFSET);
 
-	*status = sts;
-	return 0;
+	while (ioread32(idxd->reg_base + IDXD_CMDSTS_OFFSET) &
+	       IDXD_CMDSTS_ACTIVE)
+		cpu_relax();
+	spin_unlock_irqrestore(&idxd->dev_lock, flags);
 }
 
-static int idxd_cmd_send(struct idxd_device *idxd, int cmd_code, u32 operand)
+static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
+			  u32 *status)
 {
 	union idxd_command_reg cmd;
-	int rc;
-	u32 status;
-
-	lockdep_assert_held(&idxd->dev_lock);
-	rc = idxd_cmd_wait(idxd, &status, IDXD_REG_TIMEOUT);
-	if (rc < 0)
-		return rc;
+	DECLARE_COMPLETION_ONSTACK(done);
+	unsigned long flags;
 
 	memset(&cmd, 0, sizeof(cmd));
 	cmd.cmd = cmd_code;
 	cmd.operand = operand;
+	cmd.int_req = 1;
+
+	spin_lock_irqsave(&idxd->dev_lock, flags);
+	wait_event_lock_irq(idxd->cmd_waitq,
+			    !test_bit(IDXD_FLAG_CMD_RUNNING, &idxd->flags),
+			    idxd->dev_lock);
+
 	dev_dbg(&idxd->pdev->dev, "%s: sending cmd: %#x op: %#x\n",
 		__func__, cmd_code, operand);
+
+	__set_bit(IDXD_FLAG_CMD_RUNNING, &idxd->flags);
+	idxd->cmd_done = &done;
 	iowrite32(cmd.bits, idxd->reg_base + IDXD_CMD_OFFSET);
 
-	return 0;
+	/*
+	 * After command submitted, release lock and go to sleep until
+	 * the command completes via interrupt.
+	 */
+	spin_unlock_irqrestore(&idxd->dev_lock, flags);
+	wait_for_completion(&done);
+	spin_lock_irqsave(&idxd->dev_lock, flags);
+	if (status)
+		*status = ioread32(idxd->reg_base + IDXD_CMDSTS_OFFSET);
+	__clear_bit(IDXD_FLAG_CMD_RUNNING, &idxd->flags);
+	/* Wake up other pending commands */
+	wake_up(&idxd->cmd_waitq);
+	spin_unlock_irqrestore(&idxd->dev_lock, flags);
 }
 
 int idxd_device_enable(struct idxd_device *idxd)
 {
 	struct device *dev = &idxd->pdev->dev;
-	int rc;
 	u32 status;
 
-	lockdep_assert_held(&idxd->dev_lock);
 	if (idxd_is_enabled(idxd)) {
 		dev_dbg(dev, "Device already enabled\n");
 		return -ENXIO;
 	}
 
-	rc = idxd_cmd_send(idxd, IDXD_CMD_ENABLE_DEVICE, 0);
-	if (rc < 0)
-		return rc;
-	rc = idxd_cmd_wait(idxd, &status, IDXD_REG_TIMEOUT);
-	if (rc < 0)
-		return rc;
+	idxd_cmd_exec(idxd, IDXD_CMD_ENABLE_DEVICE, 0, &status);
 
 	/* If the command is successful or if the device was enabled */
 	if (status != IDXD_CMDSTS_SUCCESS &&
@@ -405,58 +419,29 @@ int idxd_device_enable(struct idxd_device *idxd)
 int idxd_device_disable(struct idxd_device *idxd)
 {
 	struct device *dev = &idxd->pdev->dev;
-	int rc;
 	u32 status;
 
-	lockdep_assert_held(&idxd->dev_lock);
 	if (!idxd_is_enabled(idxd)) {
 		dev_dbg(dev, "Device is not enabled\n");
 		return 0;
 	}
 
-	rc = idxd_cmd_send(idxd, IDXD_CMD_DISABLE_DEVICE, 0);
-	if (rc < 0)
-		return rc;
-	rc = idxd_cmd_wait(idxd, &status, IDXD_REG_TIMEOUT);
-	if (rc < 0)
-		return rc;
+	idxd_cmd_exec(idxd, IDXD_CMD_DISABLE_DEVICE, 0, &status);
 
 	/* If the command is successful or if the device was disabled */
 	if (status != IDXD_CMDSTS_SUCCESS &&
 	    !(status & IDXD_CMDSTS_ERR_DIS_DEV_EN)) {
 		dev_dbg(dev, "%s: err_code: %#x\n", __func__, status);
-		rc = -ENXIO;
-		return rc;
+		return -ENXIO;
 	}
 
 	idxd->state = IDXD_DEV_CONF_READY;
 	return 0;
 }
 
-int __idxd_device_reset(struct idxd_device *idxd)
-{
-	u32 status;
-	int rc;
-
-	rc = idxd_cmd_send(idxd, IDXD_CMD_RESET_DEVICE, 0);
-	if (rc < 0)
-		return rc;
-	rc = idxd_cmd_wait(idxd, &status, IDXD_REG_TIMEOUT);
-	if (rc < 0)
-		return rc;
-
-	return 0;
-}
-
-int idxd_device_reset(struct idxd_device *idxd)
+void idxd_device_reset(struct idxd_device *idxd)
 {
-	unsigned long flags;
-	int rc;
-
-	spin_lock_irqsave(&idxd->dev_lock, flags);
-	rc = __idxd_device_reset(idxd);
-	spin_unlock_irqrestore(&idxd->dev_lock, flags);
-	return rc;
+	idxd_cmd_exec(idxd, IDXD_CMD_RESET_DEVICE, 0, NULL);
 }
 
 /* Device configuration bits */