iommu/arm-smmu: Streamline SMMU data lookups

Simplify things somewhat by stashing our arm_smmu_device instance in
drvdata, so that it's readily available to our driver model callbacks.
Then we can excise the private list entirely, since the driver core
already has a perfectly good list of SMMU devices we can use in the one
instance we actually need to. Finally, make a further modest code saving
with the relatively new of_device_get_match_data() helper.

Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/arm-smmu.c

@@ -41,6 +41,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_device.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -370,8 +371,6 @@ struct arm_smmu_device {
 	u32				num_context_irqs;
 	unsigned int			*irqs;
 
-	struct list_head		list;
-
 	u32				cavium_id_base; /* Specific to Cavium */
 };
 
@@ -409,9 +408,6 @@ struct arm_smmu_domain {
 	struct iommu_domain		domain;
 };
 
-static DEFINE_SPINLOCK(arm_smmu_devices_lock);
-static LIST_HEAD(arm_smmu_devices);
-
 struct arm_smmu_option_prop {
 	u32 opt;
 	const char *prop;
@@ -478,6 +474,8 @@ static int __find_legacy_master_phandle(struct device *dev, void *data)
 	return err == -ENOENT ? 0 : err;
 }
 
+static struct platform_driver arm_smmu_driver;
+
 static int arm_smmu_register_legacy_master(struct device *dev)
 {
 	struct arm_smmu_device *smmu;
@@ -495,19 +493,16 @@ static int arm_smmu_register_legacy_master(struct device *dev)
 	}
 
 	it.node = np;
-	spin_lock(&arm_smmu_devices_lock);
-	list_for_each_entry(smmu, &arm_smmu_devices, list) {
-		err = __find_legacy_master_phandle(smmu->dev, &data);
-		if (err)
-			break;
-	}
-	spin_unlock(&arm_smmu_devices_lock);
+	err = driver_for_each_device(&arm_smmu_driver.driver, NULL, &data,
+				     __find_legacy_master_phandle);
 	of_node_put(np);
 	if (err == 0)
 		return -ENODEV;
 	if (err < 0)
 		return err;
 
+	smmu = dev_get_drvdata(data);
+
 	if (it.cur_count > MAX_MASTER_STREAMIDS) {
 		dev_err(smmu->dev,
 			"reached maximum number (%d) of stream IDs for master device %s\n",
@@ -1816,7 +1811,6 @@ MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
 
 static int arm_smmu_device_dt_probe(struct platform_device *pdev)
 {
-	const struct of_device_id *of_id;
 	const struct arm_smmu_match_data *data;
 	struct resource *res;
 	struct arm_smmu_device *smmu;
@@ -1830,8 +1824,7 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)
 	}
 	smmu->dev = dev;
 
-	of_id = of_match_node(arm_smmu_of_match, dev->of_node);
-	data = of_id->data;
+	data = of_device_get_match_data(dev);
 	smmu->version = data->version;
 	smmu->model = data->model;
 
@@ -1904,35 +1897,20 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)
 		}
 	}
 
-	INIT_LIST_HEAD(&smmu->list);
-	spin_lock(&arm_smmu_devices_lock);
-	list_add(&smmu->list, &arm_smmu_devices);
-	spin_unlock(&arm_smmu_devices_lock);
-
+	platform_set_drvdata(pdev, smmu);
 	arm_smmu_device_reset(smmu);
 	return 0;
 }
 
 static int arm_smmu_device_remove(struct platform_device *pdev)
 {
-	struct device *dev = &pdev->dev;
-	struct arm_smmu_device *curr, *smmu = NULL;
-
-	spin_lock(&arm_smmu_devices_lock);
-	list_for_each_entry(curr, &arm_smmu_devices, list) {
-		if (curr->dev == dev) {
-			smmu = curr;
-			list_del(&smmu->list);
-			break;
-		}
-	}
-	spin_unlock(&arm_smmu_devices_lock);
+	struct arm_smmu_device *smmu = platform_get_drvdata(pdev);
 
 	if (!smmu)
 		return -ENODEV;
 
 	if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
-		dev_err(dev, "removing device with active domains!\n");
+		dev_err(&pdev->dev, "removing device with active domains!\n");
 
 	/* Turn the thing off */
 	writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);