iommu/omap: streamline enable/disable through runtime pm callbacks

The OMAP IOMMU devices are typically present within the respective
client processor subsystem and have their own dedicated hard-reset
line. Enabling an IOMMU requires the reset line to be deasserted
and the clocks to be enabled before programming the necessary IOMMU
registers. The IOMMU disable sequence follow the reverse order of
enabling. The OMAP IOMMU driver programs the reset lines through
pdata ops to invoke the omap_device_assert/deassert_hardreset API.
The clocks are managed through the pm_runtime framework, and the
callbacks associated with the device's pm_domain, implemented in
the omap_device layer.

Streamline the enable and disable sequences in the OMAP IOMMU
driver by implementing all the above operations within the
runtime pm callbacks. All the OMAP devices have device pm_domain
callbacks plugged in the omap_device layer for automatic runtime
management of the clocks. Invoking the reset management functions
within the runtime pm callbacks in OMAP IOMMU driver therefore
requires that the default device's pm domain callbacks in the
omap_device layer be reset, as the ordering sequence for managing
the reset lines and clocks from the pm_domain callbacks don't gel
well with the implementation in the IOMMU driver callbacks. The
omap_device_enable/omap_device_idle functions are invoked through
the newly added pdata ops.

Consolidating all the device management sequences within the
runtime pm callbacks allows the driver to easily support both
system suspend/resume and runtime suspend/resume using common
code.
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/omap-iommu.c

@@ -186,53 +186,18 @@ static void omap2_iommu_disable(struct omap_iommu *obj)
 
 static int iommu_enable(struct omap_iommu *obj)
 {
-	int err;
-	struct platform_device *pdev = to_platform_device(obj->dev);
-	struct iommu_platform_data *pdata = dev_get_platdata(&pdev->dev);
-
-	if (pdata && pdata->set_pwrdm_constraint) {
-		err = pdata->set_pwrdm_constraint(pdev, true, &obj->pwrst);
-		if (err) {
-			dev_warn(obj->dev, "pwrdm_constraint failed to be set, status = %d\n",
-				 err);
-		}
-	}
-
-	if (pdata && pdata->deassert_reset) {
-		err = pdata->deassert_reset(pdev, pdata->reset_name);
-		if (err) {
-			dev_err(obj->dev, "deassert_reset failed: %d\n", err);
-			return err;
-		}
-	}
-
-	pm_runtime_get_sync(obj->dev);
+	int ret;
 
-	err = omap2_iommu_enable(obj);
+	ret = pm_runtime_get_sync(obj->dev);
+	if (ret < 0)
+		pm_runtime_put_noidle(obj->dev);
 
-	return err;
+	return ret < 0 ? ret : 0;
 }
 
 static void iommu_disable(struct omap_iommu *obj)
 {
-	struct platform_device *pdev = to_platform_device(obj->dev);
-	struct iommu_platform_data *pdata = dev_get_platdata(&pdev->dev);
-	int ret;
-
-	omap2_iommu_disable(obj);
-
 	pm_runtime_put_sync(obj->dev);
-
-	if (pdata && pdata->assert_reset)
-		pdata->assert_reset(pdev, pdata->reset_name);
-
-	if (pdata && pdata->set_pwrdm_constraint) {
-		ret = pdata->set_pwrdm_constraint(pdev, false, &obj->pwrst);
-		if (ret) {
-			dev_warn(obj->dev, "pwrdm_constraint failed to be reset, status = %d\n",
-				 ret);
-		}
-	}
 }
 
 /*
@@ -927,6 +892,85 @@ static void omap_iommu_detach(struct omap_iommu *obj)
 	dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);
 }
 
+/**
+ * omap_iommu_runtime_suspend - disable an iommu device
+ * @dev:	iommu device
+ *
+ * This function performs all that is necessary to disable an
+ * IOMMU device, either during final detachment from a client
+ * device, or during system/runtime suspend of the device. This
+ * includes programming all the appropriate IOMMU registers, and
+ * managing the associated omap_hwmod's state and the device's
+ * reset line.
+ **/
+static int omap_iommu_runtime_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct iommu_platform_data *pdata = dev_get_platdata(dev);
+	struct omap_iommu *obj = to_iommu(dev);
+	int ret;
+
+	omap2_iommu_disable(obj);
+
+	if (pdata && pdata->device_idle)
+		pdata->device_idle(pdev);
+
+	if (pdata && pdata->assert_reset)
+		pdata->assert_reset(pdev, pdata->reset_name);
+
+	if (pdata && pdata->set_pwrdm_constraint) {
+		ret = pdata->set_pwrdm_constraint(pdev, false, &obj->pwrst);
+		if (ret) {
+			dev_warn(obj->dev, "pwrdm_constraint failed to be reset, status = %d\n",
+				 ret);
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * omap_iommu_runtime_resume - enable an iommu device
+ * @dev:	iommu device
+ *
+ * This function performs all that is necessary to enable an
+ * IOMMU device, either during initial attachment to a client
+ * device, or during system/runtime resume of the device. This
+ * includes programming all the appropriate IOMMU registers, and
+ * managing the associated omap_hwmod's state and the device's
+ * reset line.
+ **/
+static int omap_iommu_runtime_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct iommu_platform_data *pdata = dev_get_platdata(dev);
+	struct omap_iommu *obj = to_iommu(dev);
+	int ret = 0;
+
+	if (pdata && pdata->set_pwrdm_constraint) {
+		ret = pdata->set_pwrdm_constraint(pdev, true, &obj->pwrst);
+		if (ret) {
+			dev_warn(obj->dev, "pwrdm_constraint failed to be set, status = %d\n",
+				 ret);
+		}
+	}
+
+	if (pdata && pdata->deassert_reset) {
+		ret = pdata->deassert_reset(pdev, pdata->reset_name);
+		if (ret) {
+			dev_err(dev, "deassert_reset failed: %d\n", ret);
+			return ret;
+		}
+	}
+
+	if (pdata && pdata->device_enable)
+		pdata->device_enable(pdev);
+
+	ret = omap2_iommu_enable(obj);
+
+	return ret;
+}
+
 static bool omap_iommu_can_register(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -1001,6 +1045,15 @@ static int omap_iommu_probe(struct platform_device *pdev)
 	if (!obj)
 		return -ENOMEM;
 
+	/*
+	 * self-manage the ordering dependencies between omap_device_enable/idle
+	 * and omap_device_assert/deassert_hardreset API
+	 */
+	if (pdev->dev.pm_domain) {
+		dev_dbg(&pdev->dev, "device pm_domain is being reset\n");
+		pdev->dev.pm_domain = NULL;
+	}
+
 	obj->name = dev_name(&pdev->dev);
 	obj->nr_tlb_entries = 32;
 	err = of_property_read_u32(of, "ti,#tlb-entries", &obj->nr_tlb_entries);
@@ -1089,6 +1142,11 @@ static int omap_iommu_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct dev_pm_ops omap_iommu_pm_ops = {
+	SET_RUNTIME_PM_OPS(omap_iommu_runtime_suspend,
+			   omap_iommu_runtime_resume, NULL)
+};
+
 static const struct of_device_id omap_iommu_of_match[] = {
 	{ .compatible = "ti,omap2-iommu" },
 	{ .compatible = "ti,omap4-iommu" },
@@ -1102,6 +1160,7 @@ static struct platform_driver omap_iommu_driver = {
 	.remove	= omap_iommu_remove,
 	.driver	= {
 		.name	= "omap-iommu",
+		.pm	= &omap_iommu_pm_ops,
 		.of_match_table = of_match_ptr(omap_iommu_of_match),
 	},
 };