We need to add support for pread'ing an LMEM object.

Signed-off-by: Matthew Auld <matthew.a...@intel.com>
Signed-off-by: Steve Hampson <steven.t.hamp...@intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Abdiel Janulgue <abdiel.janul...@linux.intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_lmem.c      | 112 ++++++++++++++++++
 drivers/gpu/drm/i915/gem/i915_gem_lmem.h      |   6 +
 .../gpu/drm/i915/gem/i915_gem_object_types.h  |   2 +
 drivers/gpu/drm/i915/i915_gem.c               |   6 +
 4 files changed, 126 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c 
b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
index 932ee21e6609..9142ba299aa1 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
@@ -8,6 +8,92 @@
 #include "gem/i915_gem_lmem.h"
 #include "i915_drv.h"
 
+static int lmem_pread(struct drm_i915_gem_object *obj,
+                     const struct drm_i915_gem_pread *arg)
+{
+       struct drm_i915_private *i915 = to_i915(obj->base.dev);
+       struct intel_runtime_pm *rpm = &i915->runtime_pm;
+       intel_wakeref_t wakeref;
+       struct dma_fence *fence;
+       char __user *user_data;
+       unsigned int offset;
+       unsigned long idx;
+       u64 remain;
+       int ret;
+
+       ret = i915_gem_object_wait(obj,
+                                  I915_WAIT_INTERRUPTIBLE,
+                                  MAX_SCHEDULE_TIMEOUT);
+       if (ret)
+               return ret;
+
+       ret = i915_gem_object_pin_pages(obj);
+       if (ret)
+               return ret;
+
+       i915_gem_object_lock(obj);
+       ret = i915_gem_object_set_to_wc_domain(obj, false);
+       if (ret) {
+               i915_gem_object_unlock(obj);
+               goto out_unpin;
+       }
+
+       fence = i915_gem_object_lock_fence(obj);
+       i915_gem_object_unlock(obj);
+       if (!fence) {
+               ret = -ENOMEM;
+               goto out_unpin;
+       }
+
+       wakeref = intel_runtime_pm_get(rpm);
+
+       remain = arg->size;
+       user_data = u64_to_user_ptr(arg->data_ptr);
+       offset = offset_in_page(arg->offset);
+       for (idx = arg->offset >> PAGE_SHIFT; remain; idx++) {
+               unsigned long unwritten;
+               void __iomem *vaddr;
+               int length;
+
+               length = remain;
+               if (offset + length > PAGE_SIZE)
+                       length = PAGE_SIZE - offset;
+
+               vaddr = i915_gem_object_lmem_io_map_page_atomic(obj, idx);
+               if (!vaddr) {
+                       ret = -ENOMEM;
+                       goto out_put;
+               }
+               unwritten = __copy_to_user_inatomic(user_data,
+                                                   (void __force *)vaddr + 
offset,
+                                                   length);
+               io_mapping_unmap_atomic(vaddr);
+               if (unwritten) {
+                       vaddr = i915_gem_object_lmem_io_map_page(obj, idx);
+                       unwritten = copy_to_user(user_data,
+                                                (void __force *)vaddr + offset,
+                                                length);
+                       io_mapping_unmap(vaddr);
+               }
+               if (unwritten) {
+                       ret = -EFAULT;
+                       goto out_put;
+               }
+
+               remain -= length;
+               user_data += length;
+               offset = 0;
+       }
+
+out_put:
+       intel_runtime_pm_put(rpm, wakeref);
+       i915_gem_object_unlock_fence(obj, fence);
+out_unpin:
+       i915_gem_object_unpin_pages(obj);
+
+       return ret;
+}
+
 const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops = {
        .name = "i915_gem_object_lmem",
        .flags = I915_GEM_OBJECT_HAS_IOMEM,
@@ -15,8 +101,34 @@ const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops 
= {
        .get_pages = i915_gem_object_get_pages_buddy,
        .put_pages = i915_gem_object_put_pages_buddy,
        .release = i915_gem_object_release_memory_region,
+
+       .pread = lmem_pread,
 };
 
+void __iomem *
+i915_gem_object_lmem_io_map_page(struct drm_i915_gem_object *obj,
+                                unsigned long n)
+{
+       resource_size_t offset;
+
+       offset = i915_gem_object_get_dma_address(obj, n);
+       offset -= obj->mm.region->region.start;
+
+       return io_mapping_map_wc(&obj->mm.region->iomap, offset, PAGE_SIZE);
+}
+
+void __iomem *
+i915_gem_object_lmem_io_map_page_atomic(struct drm_i915_gem_object *obj,
+                                       unsigned long n)
+{
+       resource_size_t offset;
+
+       offset = i915_gem_object_get_dma_address(obj, n);
+       offset -= obj->mm.region->region.start;
+
+       return io_mapping_map_atomic_wc(&obj->mm.region->iomap, offset);
+}
+
 bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj)
 {
        return obj->ops == &i915_gem_lmem_obj_ops;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.h 
b/drivers/gpu/drm/i915/gem/i915_gem_lmem.h
index fc3f15580fe3..a24d94bc380f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.h
@@ -14,6 +14,12 @@ struct intel_memory_region;
 
 extern const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops;
 
+void __iomem *i915_gem_object_lmem_io_map_page(struct drm_i915_gem_object *obj,
+                                              unsigned long n);
+void __iomem *
+i915_gem_object_lmem_io_map_page_atomic(struct drm_i915_gem_object *obj,
+                                       unsigned long n);
+
 bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj);
 
 struct drm_i915_gem_object *
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h 
b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 5335f799b548..b37ae7b32f53 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -56,6 +56,8 @@ struct drm_i915_gem_object_ops {
        void (*truncate)(struct drm_i915_gem_object *obj);
        void (*writeback)(struct drm_i915_gem_object *obj);
 
+       int (*pread)(struct drm_i915_gem_object *,
+                    const struct drm_i915_gem_pread *arg);
        int (*pwrite)(struct drm_i915_gem_object *obj,
                      const struct drm_i915_gem_pwrite *arg);
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 9aa3066cb75d..1805b5e6bc30 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -519,6 +519,12 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
 
        trace_i915_gem_object_pread(obj, args->offset, args->size);
 
+       ret = -ENODEV;
+       if (obj->ops->pread)
+               ret = obj->ops->pread(obj, args);
+       if (ret != -ENODEV)
+               goto out;
+
        ret = i915_gem_object_wait(obj,
                                   I915_WAIT_INTERRUPTIBLE,
                                   MAX_SCHEDULE_TIMEOUT);
-- 
2.26.2

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