[V4,2/6] iommu/arm-smmu: Add pm_runtime/sleep ops

Commit Message

Vivek Gautam July 6, 2017, 9:37 a.m. UTC

From: Sricharan R <[e-mail]>

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.

Signed-off-by: Sricharan R <[e-mail]>
Signed-off-by: Archit Taneja <[e-mail]>
[vivek: Clock rework to loop over clock names data]
Signed-off-by: Vivek Gautam <[e-mail]>
---
 drivers/iommu/arm-smmu.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 94 insertions(+), 1 deletion(-)

Comments

Stephen Boyd July 12, 2017, 10:58 p.m. UTC | #1

On 07/06, Vivek Gautam wrote:
> From: Sricharan R <[e-mail]>
> 
> 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.
> 
> Signed-off-by: Sricharan R <[e-mail]>
> Signed-off-by: Archit Taneja <[e-mail]>
> [vivek: Clock rework to loop over clock names data]
> Signed-off-by: Vivek Gautam <[e-mail]>
> ---

General comment, we have a bulk clk API now, but I guess we
failed to add the clk_bulk_prepare_enable() API that could be
used here. Perhaps you can add that API and then use it here to
reduce lines of code.

Stephen Boyd July 12, 2017, 11:01 p.m. UTC | #2

On 07/12, Stephen Boyd wrote:
> On 07/06, Vivek Gautam wrote:
> > From: Sricharan R <[e-mail]>
> > 
> > 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.
> > 
> > Signed-off-by: Sricharan R <[e-mail]>
> > Signed-off-by: Archit Taneja <[e-mail]>
> > [vivek: Clock rework to loop over clock names data]
> > Signed-off-by: Vivek Gautam <[e-mail]>
> > ---
> 
> General comment, we have a bulk clk API now, but I guess we
> failed to add the clk_bulk_prepare_enable() API that could be
> used here. Perhaps you can add that API and then use it here to
> reduce lines of code.
> 

Bjorn just sent a patch for that API an hour ago.

Vivek Gautam July 13, 2017, 3:57 a.m. UTC | #3

On 07/13/2017 04:31 AM, Stephen Boyd wrote:
> On 07/12, Stephen Boyd wrote:
>> On 07/06, Vivek Gautam wrote:
>>> From: Sricharan R <[e-mail]>
>>>
>>> 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.
>>>
>>> Signed-off-by: Sricharan R <[e-mail]>
>>> Signed-off-by: Archit Taneja <[e-mail]>
>>> [vivek: Clock rework to loop over clock names data]
>>> Signed-off-by: Vivek Gautam <[e-mail]>
>>> ---
>> General comment, we have a bulk clk API now, but I guess we
>> failed to add the clk_bulk_prepare_enable() API that could be
>> used here. Perhaps you can add that API and then use it here to
>> reduce lines of code.

Sure, will use the bulk clock APIs to handle the clocks.

Best regards
Vivek

>>
> Bjorn just sent a patch for that API an hour ago.
>

Patch

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 61b1f8729a7c..bfe613f8939c 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -48,6 +48,7 @@ 
 #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>
 
@@ -196,6 +197,9 @@  struct arm_smmu_device {
 	u32				num_global_irqs;
 	u32				num_context_irqs;
 	unsigned int			*irqs;
+	int                             num_clks;
+	struct clk                      **clocks;
+	const char * const		*clk_names;
 
 	u32				cavium_id_base; /* Specific to Cavium */
 
@@ -272,6 +276,32 @@  static void parse_driver_options(struct arm_smmu_device *smmu)
 	} while (arm_smmu_options[++i].opt);
 }
 
+static int arm_smmu_enable_clocks(struct arm_smmu_device *smmu)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < smmu->num_clks; ++i) {
+		ret = clk_prepare_enable(smmu->clocks[i]);
+		if (ret) {
+			dev_err(smmu->dev, "Couldn't enable %s clock\n",
+				smmu->clk_names[i]);
+			while (i--)
+				clk_disable_unprepare(smmu->clocks[i]);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void arm_smmu_disable_clocks(struct arm_smmu_device *smmu)
+{
+	int i = smmu->num_clks;
+
+	while (i--)
+		clk_disable_unprepare(smmu->clocks[i]);
+}
+
 static struct device_node *dev_get_dev_node(struct device *dev)
 {
 	if (dev_is_pci(dev)) {
@@ -1626,6 +1656,36 @@  static int arm_smmu_id_size_to_bits(int size)
 	}
 }
 
+static int arm_smmu_init_clocks(struct arm_smmu_device *smmu)
+{
+	int i, err;
+	struct device *dev = smmu->dev;
+
+	if (smmu->num_clks < 1)
+		return 0;
+
+	smmu->clocks = devm_kcalloc(dev, smmu->num_clks,
+				    sizeof(*smmu->clocks), GFP_KERNEL);
+	if (!smmu->clocks)
+		return -ENOMEM;
+
+	for (i = 0; i < smmu->num_clks; i++) {
+		const char *cname = smmu->clk_names[i];
+		struct clk *c = devm_clk_get(dev, cname);
+
+		if (IS_ERR(c)) {
+			err = PTR_ERR(c);
+			if (err != -EPROBE_DEFER)
+				dev_err(dev, "Couldn't get clock: %s", cname);
+
+			return err;
+		}
+		smmu->clocks[i] = c;
+	}
+
+	return 0;
+}
+
 static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 {
 	unsigned long size;
@@ -1833,10 +1893,12 @@  static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 struct arm_smmu_match_data {
 	enum arm_smmu_arch_version version;
 	enum arm_smmu_implementation model;
+	const char * const *clks;
+	int num_clks;
 };
 
 #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);
@@ -1937,6 +1999,8 @@  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->clk_names = data->clks;
+	smmu->num_clks = data->num_clks;
 
 	parse_driver_options(smmu);
 
@@ -2035,6 +2099,10 @@  static int arm_smmu_device_probe(struct platform_device *pdev)
 		smmu->irqs[i] = irq;
 	}
 
+	err = arm_smmu_init_clocks(smmu);
+	if (err)
+		return err;
+
 	err = arm_smmu_device_cfg_probe(smmu);
 	if (err)
 		return err;
@@ -2120,10 +2188,35 @@  static int arm_smmu_device_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int arm_smmu_resume(struct device *dev)
+{
+	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+
+	return arm_smmu_enable_clocks(smmu);
+}
+
+static int arm_smmu_suspend(struct device *dev)
+{
+	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+
+	arm_smmu_disable_clocks(smmu);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops arm_smmu_pm_ops = {
+	SET_RUNTIME_PM_OPS(arm_smmu_suspend, arm_smmu_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+};
+
 static struct platform_driver arm_smmu_driver = {
 	.driver	= {
 		.name		= "arm-smmu",
 		.of_match_table	= of_match_ptr(arm_smmu_of_match),
+		.pm = &arm_smmu_pm_ops,
 	},
 	.probe	= arm_smmu_device_probe,
 	.remove	= arm_smmu_device_remove,