dmaengine: idxd: add support for readonly config mode

The read-only configuration mode is defined by the DSA spec as a mode of
the device WQ configuration. When GENCAP register bit 31 is set to 0,
the device is in RO mode and group configuration and some fields of the
workqueue configuration registers are read-only and reflect the fixed
configuration of the device. Add support for RO mode. The driver will
load the values from the registers directly setup all the internally
cached data structures based on the device configuration.

Signed-off-by: Dave Jiang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/idxd/device.c

···
 
 	return 0;
 }
+
+static int idxd_wq_load_config(struct idxd_wq *wq)
+{
+	struct idxd_device *idxd = wq->idxd;
+	struct device *dev = &idxd->pdev->dev;
+	int wqcfg_offset;
+	int i;
+
+	wqcfg_offset = WQCFG_OFFSET(idxd, wq->id, 0);
+	memcpy_fromio(wq->wqcfg, idxd->reg_base + wqcfg_offset, idxd->wqcfg_size);
+
+	wq->size = wq->wqcfg->wq_size;
+	wq->threshold = wq->wqcfg->wq_thresh;
+	if (wq->wqcfg->priv)
+		wq->type = IDXD_WQT_KERNEL;
+
+	/* The driver does not support shared WQ mode in read-only config yet */
+	if (wq->wqcfg->mode == 0 || wq->wqcfg->pasid_en)
+		return -EOPNOTSUPP;
+
+	set_bit(WQ_FLAG_DEDICATED, &wq->flags);
+
+	wq->priority = wq->wqcfg->priority;
+
+	for (i = 0; i < WQCFG_STRIDES(idxd); i++) {
+		wqcfg_offset = WQCFG_OFFSET(idxd, wq->id, i);
+		dev_dbg(dev, "WQ[%d][%d][%#x]: %#x\n", wq->id, i, wqcfg_offset, wq->wqcfg->bits[i]);
+	}
+
+	return 0;
+}
+
+static void idxd_group_load_config(struct idxd_group *group)
+{
+	struct idxd_device *idxd = group->idxd;
+	struct device *dev = &idxd->pdev->dev;
+	int i, j, grpcfg_offset;
+
+	/*
+	 * Load WQS bit fields
+	 * Iterate through all 256 bits 64 bits at a time
+	 */
+	for (i = 0; i < GRPWQCFG_STRIDES; i++) {
+		struct idxd_wq *wq;
+
+		grpcfg_offset = GRPWQCFG_OFFSET(idxd, group->id, i);
+		group->grpcfg.wqs[i] = ioread64(idxd->reg_base + grpcfg_offset);
+		dev_dbg(dev, "GRPCFG wq[%d:%d: %#x]: %#llx\n",
+			group->id, i, grpcfg_offset, group->grpcfg.wqs[i]);
+
+		if (i * 64 >= idxd->max_wqs)
+			break;
+
+		/* Iterate through all 64 bits and check for wq set */
+		for (j = 0; j < 64; j++) {
+			int id = i * 64 + j;
+
+			/* No need to check beyond max wqs */
+			if (id >= idxd->max_wqs)
+				break;
+
+			/* Set group assignment for wq if wq bit is set */
+			if (group->grpcfg.wqs[i] & BIT(j)) {
+				wq = idxd->wqs[id];
+				wq->group = group;
+			}
+		}
+	}
+
+	grpcfg_offset = GRPENGCFG_OFFSET(idxd, group->id);
+	group->grpcfg.engines = ioread64(idxd->reg_base + grpcfg_offset);
+	dev_dbg(dev, "GRPCFG engs[%d: %#x]: %#llx\n", group->id,
+		grpcfg_offset, group->grpcfg.engines);
+
+	/* Iterate through all 64 bits to check engines set */
+	for (i = 0; i < 64; i++) {
+		if (i >= idxd->max_engines)
+			break;
+
+		if (group->grpcfg.engines & BIT(i)) {
+			struct idxd_engine *engine = idxd->engines[i];
+
+			engine->group = group;
+		}
+	}
+
+	grpcfg_offset = GRPFLGCFG_OFFSET(idxd, group->id);
+	group->grpcfg.flags.bits = ioread32(idxd->reg_base + grpcfg_offset);
+	dev_dbg(dev, "GRPFLAGS flags[%d: %#x]: %#x\n",
+		group->id, grpcfg_offset, group->grpcfg.flags.bits);
+}
+
+int idxd_device_load_config(struct idxd_device *idxd)
+{
+	union gencfg_reg reg;
+	int i, rc;
+
+	reg.bits = ioread32(idxd->reg_base + IDXD_GENCFG_OFFSET);
+	idxd->token_limit = reg.token_limit;
+
+	for (i = 0; i < idxd->max_groups; i++) {
+		struct idxd_group *group = idxd->groups[i];
+
+		idxd_group_load_config(group);
+	}
+
+	for (i = 0; i < idxd->max_wqs; i++) {
+		struct idxd_wq *wq = idxd->wqs[i];
+
+		rc = idxd_wq_load_config(wq);
+		if (rc < 0)
+			return rc;
+	}
+
+	return 0;
+}

drivers/dma/idxd/idxd.h

···
 int idxd_device_config(struct idxd_device *idxd);
 void idxd_device_wqs_clear_state(struct idxd_device *idxd);
 void idxd_device_drain_pasid(struct idxd_device *idxd, int pasid);
+int idxd_device_load_config(struct idxd_device *idxd);
 
 /* work queue control */
 int idxd_wq_alloc_resources(struct idxd_wq *wq);

drivers/dma/idxd/init.c

···
 	if (rc)
 		goto err;
 
+	/* If the configs are readonly, then load them from device */
+	if (!test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags)) {
+		dev_dbg(dev, "Loading RO device config\n");
+		rc = idxd_device_load_config(idxd);
+		if (rc < 0)
+			goto err;
+	}
+
 	rc = idxd_setup_interrupts(idxd);
 	if (rc)
 		goto err;

drivers/dma/idxd/sysfs.c

···
 	}
 
 	spin_lock_irqsave(&idxd->dev_lock, flags);
-	rc = idxd_device_config(idxd);
+	if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
+		rc = idxd_device_config(idxd);
 	spin_unlock_irqrestore(&idxd->dev_lock, flags);
 	if (rc < 0) {
 		mutex_unlock(&wq->wq_lock);
···
 
 static int idxd_config_bus_probe(struct device *dev)
 {
-	int rc;
+	int rc = 0;
 	unsigned long flags;
 
 	dev_dbg(dev, "%s called\n", __func__);
···
 
 		/* Perform IDXD configuration and enabling */
 		spin_lock_irqsave(&idxd->dev_lock, flags);
-		rc = idxd_device_config(idxd);
+		if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
+			rc = idxd_device_config(idxd);
 		spin_unlock_irqrestore(&idxd->dev_lock, flags);
 		if (rc < 0) {
 			module_put(THIS_MODULE);
···
 
 		idxd_unregister_dma_device(idxd);
 		rc = idxd_device_disable(idxd);
-		for (i = 0; i < idxd->max_wqs; i++) {
-			struct idxd_wq *wq = idxd->wqs[i];
+		if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags)) {
+			for (i = 0; i < idxd->max_wqs; i++) {
+				struct idxd_wq *wq = idxd->wqs[i];
 
-			mutex_lock(&wq->wq_lock);
-			idxd_wq_disable_cleanup(wq);
-			mutex_unlock(&wq->wq_lock);
+				mutex_lock(&wq->wq_lock);
+				idxd_wq_disable_cleanup(wq);
+				mutex_unlock(&wq->wq_lock);
+			}
 		}
 		module_put(THIS_MODULE);
 		if (rc < 0)