Re: [PATCH 6/6] iommu/arm-smmu: Make use of phandle iterators in device-tree parsing

From: Robin Murphy
Date: Tue Mar 22 2016 - 14:53:57 EST


Hi Joerg,

On 22/03/16 17:58, Joerg Roedel wrote:
From: Joerg Roedel <jroedel@xxxxxxx>

Remove the usage of of_parse_phandle_with_args() and replace
it by the phandle-iterator implementation so that we can
parse out all of the potentially present 128 stream-ids.

In a stream-matching implementation, a device may quite legitimately own anything up to _all_ of the stream IDs (32768, or 65536 if we ever implement support for the SMMUv2 EXID extension), so this is only a genuine limit for stream indexing (and if anyone ever actually made one of those, I don't think they're running mainline on it).

Alternatively, how straightforward is it to change the DT on your machine? I'll be getting a v2 of [1] out in a couple of weeks (after imminent holidays), which already gets rid of MAX_MASTER_STREAMIDS altogether, and might also have grown proper SMR support by then.

Robin.

[1]:http://thread.gmane.org/gmane.linux.kernel.iommu/12454

Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
---
drivers/iommu/arm-smmu.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 59ee4b8..413bd64 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -48,7 +48,7 @@
#include "io-pgtable.h"

/* Maximum number of stream IDs assigned to a single device */
-#define MAX_MASTER_STREAMIDS MAX_PHANDLE_ARGS
+#define MAX_MASTER_STREAMIDS 128

/* Maximum number of context banks per SMMU */
#define ARM_SMMU_MAX_CBS 128
@@ -349,6 +349,12 @@ struct arm_smmu_domain {
struct iommu_domain domain;
};

+struct arm_smmu_phandle_args {
+ struct device_node *np;
+ int args_count;
+ uint32_t args[MAX_MASTER_STREAMIDS];
+};
+
static struct iommu_ops arm_smmu_ops;

static DEFINE_SPINLOCK(arm_smmu_devices_lock);
@@ -458,7 +464,7 @@ static int insert_smmu_master(struct arm_smmu_device *smmu,

static int register_smmu_master(struct arm_smmu_device *smmu,
struct device *dev,
- struct of_phandle_args *masterspec)
+ struct arm_smmu_phandle_args *masterspec)
{
int i;
struct arm_smmu_master *master;
@@ -1716,7 +1722,8 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)
struct arm_smmu_device *smmu;
struct device *dev = &pdev->dev;
struct rb_node *node;
- struct of_phandle_args masterspec;
+ struct of_phandle_iterator it;
+ struct arm_smmu_phandle_args masterspec;
int num_irqs, i, err;

smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
@@ -1777,9 +1784,14 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)

i = 0;
smmu->masters = RB_ROOT;
- while (!of_parse_phandle_with_args(dev->of_node, "mmu-masters",
- "#stream-id-cells", i,
- &masterspec)) {
+
+ of_for_each_phandle(&it, err, dev->of_node,
+ "mmu-masters", "#stream-id-cells", 0) {
+ int count = of_phandle_iterator_args(&it, masterspec.args,
+ MAX_MASTER_STREAMIDS);
+ masterspec.np = of_node_get(it.node);
+ masterspec.args_count = count;
+
err = register_smmu_master(smmu, dev, &masterspec);
if (err) {
dev_err(dev, "failed to add master %s\n",
@@ -1789,6 +1801,10 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)

i++;
}
+
+ if (i == 0)
+ goto out_put_masters;
+
dev_notice(dev, "registered %d master devices\n", i);

parse_driver_options(smmu);