[PATCH v2 16/37] drm/i915/lmem: support pread

[Matthew Auld <matthew.auld@intel.com>]

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

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
---
 .../gpu/drm/i915/gem/i915_gem_object_types.h  |  2 +
 drivers/gpu/drm/i915/i915_gem.c               |  6 ++
 drivers/gpu/drm/i915/intel_region_lmem.c      | 76 +++++++++++++++++++
 3 files changed, 84 insertions(+)

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 80ff5ad9bc07..8cdee185251a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -52,6 +52,8 @@ 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 85677ae89849..4ba386ab35e7 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -463,6 +463,12 @@ 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);
diff --git a/drivers/gpu/drm/i915/intel_region_lmem.c b/drivers/gpu/drm/i915/intel_region_lmem.c
index 701bcac3479e..54b2c7bf177d 100644
--- a/drivers/gpu/drm/i915/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/intel_region_lmem.c
@@ -7,10 +7,86 @@
 #include "intel_memory_region.h"
 #include "intel_region_lmem.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_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(obj, idx);
+		if (!vaddr) {
+			ret = -ENOMEM;
+			goto out_put;
+		}
+
+		unwritten = copy_to_user(user_data,
+					 (void __force *)vaddr + offset,
+					 length);
+		io_mapping_unmap_atomic(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;
+}
+
 static const struct drm_i915_gem_object_ops region_lmem_obj_ops = {
 	.get_pages = i915_memory_region_get_pages_buddy,
 	.put_pages = i915_memory_region_put_pages_buddy,
 	.release = i915_gem_object_release_memory_region,
+
+	.pread = lmem_pread,
 };
 
 static struct drm_i915_gem_object *
-- 
2.20.1

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