[PATCH v18 1/5] iommu/arm-smmu: Add pm_runtime/sleep ops

[Vivek Gautam]

From: Sricharan R <sricharan@xxxxxxxxxxxxxx>

The smmu needs to be functional only when the respective
master's using it are active. The device_link feature
helps to track such functional dependencies, so that the
iommu gets powered when the master device enables itself
using pm_runtime. So by adapting the smmu driver for
runtime pm, above said dependency can be addressed.

This patch adds the pm runtime/sleep callbacks to the
driver and also the functions to parse the smmu clocks
from DT and enable them in resume/suspend.
We pull all the information about clocks from device tree.

Also, while we enable the runtime pm add a pm sleep suspend
callback that pushes devices to low power state by turning
the clocks off in a system sleep.
Also add corresponding clock enable path in resume callback.

Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
[Thor: Rework to get clocks from device tree]
Signed-off-by: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx>
[vivek: rework for clock and pm ops]
Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
---
 drivers/iommu/arm-smmu.c | 100 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 97 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 5a28ae892504..e47c840fc6a8 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -44,10 +44,12 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_clk.h>
 #include <linux/of_device.h>
 #include <linux/of_iommu.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 
@@ -206,6 +208,8 @@ struct arm_smmu_device {
 	u32				num_global_irqs;
 	u32				num_context_irqs;
 	unsigned int			*irqs;
+	struct clk_bulk_data		*clks;
+	int				num_clks;
 
 	u32				cavium_id_base; /* Specific to Cavium */
 
@@ -1947,7 +1951,7 @@ struct arm_smmu_match_data {
 };
 
 #define ARM_SMMU_MATCH_DATA(name, ver, imp)	\
-static struct arm_smmu_match_data name = { .version = ver, .model = imp }
+static const struct arm_smmu_match_data name = { .version = ver, .model = imp }
 
 ARM_SMMU_MATCH_DATA(smmu_generic_v1, ARM_SMMU_V1, GENERIC_SMMU);
 ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU);
@@ -1966,6 +1970,23 @@ static const struct of_device_id arm_smmu_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
 
+static void arm_smmu_fill_clk_data(struct arm_smmu_device *smmu,
+				   const char * const *clks)
+{
+	int i;
+
+	if (smmu->num_clks < 1)
+		return;
+
+	smmu->clks = devm_kcalloc(smmu->dev, smmu->num_clks,
+				  sizeof(*smmu->clks), GFP_KERNEL);
+	if (!smmu->clks)
+		return;
+
+	for (i = 0; i < smmu->num_clks; i++)
+		smmu->clks[i].id = clks[i];
+}
+
 #ifdef CONFIG_ACPI
 static int acpi_smmu_get_data(u32 model, struct arm_smmu_device *smmu)
 {
@@ -2038,6 +2059,7 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
 	const struct arm_smmu_match_data *data;
 	struct device *dev = &pdev->dev;
 	bool legacy_binding;
+	const char **parent_names;
 
 	if (of_property_read_u32(dev->of_node, "#global-interrupts",
 				 &smmu->num_global_irqs)) {
@@ -2048,6 +2070,26 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
 	data = of_device_get_match_data(dev);
 	smmu->version = data->version;
 	smmu->model = data->model;
+	smmu->num_clks = of_clk_get_parent_count(dev->of_node);
+	/* check to see if clocks were specified in DT */
+	if (smmu->num_clks) {
+		unsigned int i;
+
+		parent_names = kmalloc_array(smmu->num_clks,
+					     sizeof(*parent_names),
+					     GFP_KERNEL);
+		if (!parent_names)
+			return -ENOMEM;
+
+		for (i = 0; i < smmu->num_clks; i++) {
+			if (of_property_read_string_index(dev->of_node,
+							  "clock-names", i,
+							  &parent_names[i]))
+				goto fail_clk_name;
+		}
+		arm_smmu_fill_clk_data(smmu, parent_names);
+		kfree(parent_names);
+	}
 
 	parse_driver_options(smmu);
 
@@ -2067,6 +2109,12 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
 		smmu->features |= ARM_SMMU_FEAT_COHERENT_WALK;
 
 	return 0;
+
+fail_clk_name:
+	kfree(parent_names);
+	/* clock-names required for clocks in devm_clk_bulk_get() */
+	dev_err(dev, "clock-names required in device tree\n");
+	return -ENODEV;
 }
 
 static void arm_smmu_bus_init(void)
@@ -2150,6 +2198,14 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 		smmu->irqs[i] = irq;
 	}
 
+	err = devm_clk_bulk_get(smmu->dev, smmu->num_clks, smmu->clks);
+	if (err)
+		return err;
+
+	err = clk_bulk_prepare_enable(smmu->num_clks, smmu->clks);
+	if (err)
+		return err;
+
 	err = arm_smmu_device_cfg_probe(smmu);
 	if (err)
 		return err;
@@ -2236,6 +2292,9 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
 
 	/* Turn the thing off */
 	writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
+
+	clk_bulk_disable_unprepare(smmu->num_clks, smmu->clks);
+
 	return 0;
 }
 
@@ -2244,15 +2303,50 @@ static void arm_smmu_device_shutdown(struct platform_device *pdev)
 	arm_smmu_device_remove(pdev);
 }
 
-static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
+static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
 {
 	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_bulk_enable(smmu->num_clks, smmu->clks);
+	if (ret)
+		return ret;
 
 	arm_smmu_device_reset(smmu);
+
+	return 0;
+}
+
+static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
+{
+	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+
+	clk_bulk_disable(smmu->num_clks, smmu->clks);
+
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(arm_smmu_pm_ops, NULL, arm_smmu_pm_resume);
+static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
+{
+	if (pm_runtime_suspended(dev))
+		return 0;
+
+	return arm_smmu_runtime_resume(dev);
+}
+
+static int __maybe_unused arm_smmu_pm_suspend(struct device *dev)
+{
+	if (pm_runtime_suspended(dev))
+		return 0;
+
+	return arm_smmu_runtime_suspend(dev);
+}
+
+static const struct dev_pm_ops arm_smmu_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(arm_smmu_pm_suspend, arm_smmu_pm_resume)
+	SET_RUNTIME_PM_OPS(arm_smmu_runtime_suspend,
+			   arm_smmu_runtime_resume, NULL)
+};
 
 static struct platform_driver arm_smmu_driver = {
 	.driver	= {
-- 
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