[PATCH 3/5] iommu/tegra-smmu: Use iommu_fwspec in .probe_/.attach_device()

Nicolin Chen
2020-09-26T08:12:35Z

The tegra_smmu_probe_device() function searches in DT for the iommu
phandler to get "smmu" pointer. This works for most of SMMU clients
that exist in the DTB. But a PCI device will not be added to iommu,
since it doesn't have a DT node.

Fortunately, for a client with a DT node, tegra_smmu_probe_device()
calls tegra_smmu_of_xlate() via tegra_smmu_configure(), while for a
PCI device, of_pci_iommu_init() in the IOMMU core calls .of_xlate()
as well, even before running tegra_smmu_probe_device(). And in both
cases, tegra_smmu_of_xlate() prepares a valid iommu_fwspec pointer
that allows us to get the mc->smmu pointer via dev_get_drvdata() by
calling driver_find_device_by_fwnode().

So this patch uses iommu_fwspec in .probe_device() and related code
for a client that does not exist in the DTB, especially a PCI one.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
drivers/iommu/tegra-smmu.c | 89 +++++++++++++++++++++++---------------
drivers/memory/tegra/mc.c | 2 +-
include/soc/tegra/mc.h | 2 +
3 files changed, 56 insertions(+), 37 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index b10e02073610..97a7185b4578 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -13,6 +13,7 @@
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
+#include <linux/dma-iommu.h>
#include <linux/dma-mapping.h>

#include <soc/tegra/ahb.h>
@@ -61,6 +62,8 @@ struct tegra_smmu_as {
u32 attr;
};

+static const struct iommu_ops tegra_smmu_ops;
+
static struct tegra_smmu_as *to_smmu_as(struct iommu_domain *dom)
{
return container_of(dom, struct tegra_smmu_as, domain);
@@ -484,60 +487,49 @@ static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
static int tegra_smmu_attach_dev(struct iommu_domain *domain,
struct device *dev)
{
+ struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
struct tegra_smmu_as *as = to_smmu_as(domain);
- struct device_node *np = dev->of_node;
- struct of_phandle_args args;
- unsigned int index = 0;
- int err = 0;
-
- while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
- &args)) {
- unsigned int swgroup = args.args[0];
-
- if (args.np != smmu->dev->of_node) {
- of_node_put(args.np);
- continue;
- }
+ int index, err = 0;

- of_node_put(args.np);
+ if (!fwspec || fwspec->ops != &tegra_smmu_ops)
+ return -ENOENT;

+ for (index = 0; index < fwspec->num_ids; index++) {
err = tegra_smmu_as_prepare(smmu, as);
- if (err < 0)
- return err;
+ if (err)
+ goto err_disable;

- tegra_smmu_enable(smmu, swgroup, as->id);
- index++;
+ tegra_smmu_enable(smmu, fwspec->ids[index], as->id);
}

if (index == 0)
return -ENODEV;

return 0;
+
+err_disable:
+ for (index--; index >= 0; index--) {
+ tegra_smmu_disable(smmu, fwspec->ids[index], as->id);
+ tegra_smmu_as_unprepare(smmu, as);
+ }
+
+ return err;
}

static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
{
+ struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
struct tegra_smmu_as *as = to_smmu_as(domain);
- struct device_node *np = dev->of_node;
struct tegra_smmu *smmu = as->smmu;
- struct of_phandle_args args;
unsigned int index = 0;

- while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
- &args)) {
- unsigned int swgroup = args.args[0];
-
- if (args.np != smmu->dev->of_node) {
- of_node_put(args.np);
- continue;
- }
-
- of_node_put(args.np);
+ if (!fwspec || fwspec->ops != &tegra_smmu_ops)
+ return;

- tegra_smmu_disable(smmu, swgroup, as->id);
+ for (index = 0; index < fwspec->num_ids; index++) {
+ tegra_smmu_disable(smmu, fwspec->ids[index], as->id);
tegra_smmu_as_unprepare(smmu, as);
- index++;
}
}

@@ -845,10 +837,25 @@ static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev,
return 0;
}

+static struct tegra_smmu *tegra_smmu_get_by_fwnode(struct fwnode_handle *fwnode)
+{
+ struct device *dev = driver_find_device_by_fwnode(&tegra_mc_driver.driver, fwnode);
+ struct tegra_mc *mc;
+
+ if (!dev)
+ return NULL;
+
+ put_device(dev);
+ mc = dev_get_drvdata(dev);
+
+ return mc->smmu;
+}
+
static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
{
struct device_node *np = dev->of_node;
struct tegra_smmu *smmu = NULL;
+ struct iommu_fwspec *fwspec;
struct of_phandle_args args;
unsigned int index = 0;
int err;
@@ -868,8 +875,6 @@ static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
* supported by the Linux kernel, so abort after the
* first match.
*/
- dev_iommu_priv_set(dev, smmu);
-
break;
}

@@ -877,8 +882,20 @@ static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
index++;
}

- if (!smmu)
- return ERR_PTR(-ENODEV);
+ /* Any device should be able to get smmu pointer using fwspec */
+ if (!smmu) {
+ fwspec = dev_iommu_fwspec_get(dev);
+ if (!fwspec || fwspec->ops != &tegra_smmu_ops)
+ return ERR_PTR(-ENODEV);
+
+ smmu = tegra_smmu_get_by_fwnode(fwspec->iommu_fwnode);
+ }
+
+ /* NULL smmu pointer means that SMMU driver is not probed yet */
+ if (unlikely(!smmu))
+ return ERR_PTR(-EPROBE_DEFER);
+
+ dev_iommu_priv_set(dev, smmu);

return &smmu->iommu;
}
diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index ec8403557ed4..4e23fd8d8433 100644
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -735,7 +735,7 @@ static const struct dev_pm_ops tegra_mc_pm_ops = {
.resume = tegra_mc_resume,
};

-static struct platform_driver tegra_mc_driver = {
+struct platform_driver tegra_mc_driver = {
.driver = {
.name = "tegra-mc",
.of_match_table = tegra_mc_of_match,
diff --git a/include/soc/tegra/mc.h b/include/soc/tegra/mc.h
index 1238e35653d1..49a4cf64c4b9 100644
--- a/include/soc/tegra/mc.h
+++ b/include/soc/tegra/mc.h
@@ -184,4 +184,6 @@ struct tegra_mc {
int tegra_mc_write_emem_configuration(struct tegra_mc *mc, unsigned long rate);
unsigned int tegra_mc_get_emem_device_count(struct tegra_mc *mc);

+extern struct platform_driver tegra_mc_driver;
+
#endif /* __SOC_TEGRA_MC_H__ */
--
2.17.1