drm/nouveau/platform: probe IOMMU if present
Tegra SoCs have an IOMMU that can be used to present non-contiguous
physical memory as contiguous to the GPU and maximize the use of large
pages in the GPU MMU, leading to performance gains. This patch adds
support for probing such a IOMMU if present and make its properties
available in the nouveau_platform_gpu structure so subsystems can take
advantage of it.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_platform.c b/drivers/gpu/drm/nouveau/nouveau_platform.c
index dc5900b..3691982 100644
--- a/drivers/gpu/drm/nouveau/nouveau_platform.c
+++ b/drivers/gpu/drm/nouveau/nouveau_platform.c
@@ -27,6 +27,7 @@
#include <linux/of.h>
#include <linux/reset.h>
#include <linux/regulator/consumer.h>
+#include <linux/iommu.h>
#include <soc/tegra/fuse.h>
#include <soc/tegra/pmc.h>
@@ -91,6 +92,71 @@
return 0;
}
+static void nouveau_platform_probe_iommu(struct device *dev,
+ struct nouveau_platform_gpu *gpu)
+{
+ int err;
+ unsigned long pgsize_bitmap;
+
+ mutex_init(&gpu->iommu.mutex);
+
+ if (iommu_present(&platform_bus_type)) {
+ gpu->iommu.domain = iommu_domain_alloc(&platform_bus_type);
+ if (IS_ERR(gpu->iommu.domain))
+ goto error;
+
+ /*
+ * A IOMMU is only usable if it supports page sizes smaller
+ * or equal to the system's PAGE_SIZE, with a preference if
+ * both are equal.
+ */
+ pgsize_bitmap = gpu->iommu.domain->ops->pgsize_bitmap;
+ if (pgsize_bitmap & PAGE_SIZE) {
+ gpu->iommu.pgshift = PAGE_SHIFT;
+ } else {
+ gpu->iommu.pgshift = fls(pgsize_bitmap & ~PAGE_MASK);
+ if (gpu->iommu.pgshift == 0) {
+ dev_warn(dev, "unsupported IOMMU page size\n");
+ goto free_domain;
+ }
+ gpu->iommu.pgshift -= 1;
+ }
+
+ err = iommu_attach_device(gpu->iommu.domain, dev);
+ if (err)
+ goto free_domain;
+
+ err = nvkm_mm_init(&gpu->iommu._mm, 0,
+ (1ULL << 40) >> gpu->iommu.pgshift, 1);
+ if (err)
+ goto detach_device;
+
+ gpu->iommu.mm = &gpu->iommu._mm;
+ }
+
+ return;
+
+detach_device:
+ iommu_detach_device(gpu->iommu.domain, dev);
+
+free_domain:
+ iommu_domain_free(gpu->iommu.domain);
+
+error:
+ gpu->iommu.domain = NULL;
+ gpu->iommu.pgshift = 0;
+ dev_err(dev, "cannot initialize IOMMU MM\n");
+}
+
+static void nouveau_platform_remove_iommu(struct device *dev,
+ struct nouveau_platform_gpu *gpu)
+{
+ if (gpu->iommu.domain) {
+ iommu_detach_device(gpu->iommu.domain, dev);
+ iommu_domain_free(gpu->iommu.domain);
+ }
+}
+
static int nouveau_platform_probe(struct platform_device *pdev)
{
struct nouveau_platform_gpu *gpu;
@@ -118,6 +184,8 @@
if (IS_ERR(gpu->clk_pwr))
return PTR_ERR(gpu->clk_pwr);
+ nouveau_platform_probe_iommu(&pdev->dev, gpu);
+
err = nouveau_platform_power_up(gpu);
if (err)
return err;
@@ -154,10 +222,15 @@
struct nouveau_drm *drm = nouveau_drm(drm_dev);
struct nvkm_device *device = nvxx_device(&drm->device);
struct nouveau_platform_gpu *gpu = nv_device_to_platform(device)->gpu;
+ int err;
nouveau_drm_device_remove(drm_dev);
- return nouveau_platform_power_down(gpu);
+ err = nouveau_platform_power_down(gpu);
+
+ nouveau_platform_remove_iommu(&pdev->dev, gpu);
+
+ return err;
}
#if IS_ENABLED(CONFIG_OF)