[PATCH v4] iommu/rockchip: Add missing set_platform_dma_ops callback

Steven Price
2023-03-31T09:53:37Z

Similar to exynos, we need a set_platform_dma_ops() callback for proper
operation on ARM 32 bit after recent changes in the IOMMU framework
(detach ops removal). But also the use of a NULL domain is confusing.

Rework the code to add support for IOMMU_DOMAIN_IDENTITY and a singleton
rk_identity_domain which is assigned to domain when using an identity
mapping rather than "detaching". This makes the code easier to reason about.

Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes since v3[1]:

* Added a dummy free callback to rk_identity_ops.

[1] https://lore.kernel.org/r/20230330144604.2431436-1-steven.price%40arm.com

drivers/iommu/rockchip-iommu.c | 61 ++++++++++++++++++++++++++--------
1 file changed, 47 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index f30db22ea5d7..ea5a3088bb7e 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -124,6 +124,7 @@ struct rk_iommudata {

static struct device *dma_dev;
static const struct rk_iommu_ops *rk_ops;
+static struct iommu_domain rk_identity_domain;

static inline void rk_table_flush(struct rk_iommu_domain *dom, dma_addr_t dma,
unsigned int count)
@@ -646,7 +647,7 @@ static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
* Ignore the return code, though, since we always zap cache
* and clear the page fault anyway.
*/
- if (iommu->domain)
+ if (iommu->domain != &rk_identity_domain)
report_iommu_fault(iommu->domain, iommu->dev, iova,
flags);
else
@@ -980,26 +981,27 @@ static int rk_iommu_enable(struct rk_iommu *iommu)
return ret;
}

-static void rk_iommu_detach_device(struct iommu_domain *domain,
- struct device *dev)
+static int rk_iommu_identity_attach(struct iommu_domain *identity_domain,
+ struct device *dev)
{
struct rk_iommu *iommu;
- struct rk_iommu_domain *rk_domain = to_rk_domain(domain);
+ struct rk_iommu_domain *rk_domain;
unsigned long flags;
int ret;

/* Allow 'virtual devices' (eg drm) to detach from domain */
iommu = rk_iommu_from_dev(dev);
if (!iommu)
- return;
+ return -ENODEV;
+
+ rk_domain = to_rk_domain(iommu->domain);

dev_dbg(dev, "Detaching from iommu domain\n");

- /* iommu already detached */
- if (iommu->domain != domain)
- return;
+ if (iommu->domain == identity_domain)
+ return 0;

- iommu->domain = NULL;
+ iommu->domain = identity_domain;

spin_lock_irqsave(&rk_domain->iommus_lock, flags);
list_del_init(&iommu->node);
@@ -1011,8 +1013,31 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
rk_iommu_disable(iommu);
pm_runtime_put(iommu->dev);
}
+
+ return 0;
}

+static void rk_iommu_identity_free(struct iommu_domain *domain)
+{
+}
+
+static struct iommu_domain_ops rk_identity_ops = {
+ .attach_dev = rk_iommu_identity_attach,
+ .free = rk_iommu_identity_free,
+};
+
+static struct iommu_domain rk_identity_domain = {
+ .type = IOMMU_DOMAIN_IDENTITY,
+ .ops = &rk_identity_ops,
+};
+
+#ifdef CONFIG_ARM
+static void rk_iommu_set_platform_dma(struct device *dev)
+{
+ WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev));
+}
+#endif
+
static int rk_iommu_attach_device(struct iommu_domain *domain,
struct device *dev)
{
@@ -1035,8 +1060,9 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
if (iommu->domain == domain)
return 0;

- if (iommu->domain)
- rk_iommu_detach_device(iommu->domain, dev);
+ ret = rk_iommu_identity_attach(&rk_identity_domain, dev);
+ if (ret)
+ return ret;

iommu->domain = domain;

@@ -1050,7 +1076,7 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,

ret = rk_iommu_enable(iommu);
if (ret)
- rk_iommu_detach_device(iommu->domain, dev);
+ WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev));

pm_runtime_put(iommu->dev);

@@ -1061,6 +1087,9 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
{
struct rk_iommu_domain *rk_domain;

+ if (type == IOMMU_DOMAIN_IDENTITY)
+ return &rk_identity_domain;
+
if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
return NULL;

@@ -1176,6 +1205,7 @@ static int rk_iommu_of_xlate(struct device *dev,
iommu_dev = of_find_device_by_node(args->np);

data->iommu = platform_get_drvdata(iommu_dev);
+ data->iommu->domain = &rk_identity_domain;
dev_iommu_priv_set(dev, data);

platform_device_put(iommu_dev);
@@ -1188,6 +1218,9 @@ static const struct iommu_ops rk_iommu_ops = {
.probe_device = rk_iommu_probe_device,
.release_device = rk_iommu_release_device,
.device_group = rk_iommu_device_group,
+#ifdef CONFIG_ARM
+ .set_platform_dma_ops = rk_iommu_set_platform_dma,
+#endif
.pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP,
.of_xlate = rk_iommu_of_xlate,
.default_domain_ops = &(const struct iommu_domain_ops) {
@@ -1343,7 +1376,7 @@ static int __maybe_unused rk_iommu_suspend(struct device *dev)
{
struct rk_iommu *iommu = dev_get_drvdata(dev);

- if (!iommu->domain)
+ if (iommu->domain == &rk_identity_domain)
return 0;

rk_iommu_disable(iommu);
@@ -1354,7 +1387,7 @@ static int __maybe_unused rk_iommu_resume(struct device *dev)
{
struct rk_iommu *iommu = dev_get_drvdata(dev);

- if (!iommu->domain)
+ if (iommu->domain == &rk_identity_domain)
return 0;

return rk_iommu_enable(iommu);
--
2.39.2