drm/radeon: add VRAM debugfs access v3

Not very fast, but makes it possible to access even the
normally inaccessible parts of VRAM from userspace.

v2: use MM_INDEX_HI for >2GB mem access, add default_llseek
v3: set inode size in the open callback

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 81 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/evergreen_reg.h b/drivers/gpu/drm/radeon/evergreen_reg.h
index 8a4e641f0e3c..a0f63ff5a5e9 100644
--- a/drivers/gpu/drm/radeon/evergreen_reg.h
+++ b/drivers/gpu/drm/radeon/evergreen_reg.h
@@ -33,6 +33,7 @@
 #define EVERGREEN_PIF_PHY0_DATA                         0xc
 #define EVERGREEN_PIF_PHY1_INDEX                        0x10
 #define EVERGREEN_PIF_PHY1_DATA                         0x14
+#define EVERGREEN_MM_INDEX_HI                           0x18
 
 #define EVERGREEN_VGA_MEMORY_BASE_ADDRESS               0x310
 #define EVERGREEN_VGA_MEMORY_BASE_ADDRESS_HIGH          0x324
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index b1f990d0eaa1..49f210c14796 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -413,6 +413,10 @@ struct radeon_mman {
         struct ttm_bo_device            bdev;
         bool                            mem_global_referenced;
         bool                            initialized;
+
+#if defined(CONFIG_DEBUG_FS)
+        struct dentry                   *vram;
+#endif
 };
 
 /* bo virtual address in a specific vm */
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 20592378b6d0..a29d7cbd62e7 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -39,12 +39,14 @@
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/swiotlb.h>
+#include <linux/debugfs.h>
 #include "radeon_reg.h"
 #include "radeon.h"
 
 #define DRM_FILE_PAGE_OFFSET (0x100000000ULL >> PAGE_SHIFT)
 
 static int radeon_ttm_debugfs_init(struct radeon_device *rdev);
+static void radeon_ttm_debugfs_fini(struct radeon_device *rdev);
 
 static struct radeon_device *radeon_get_rdev(struct ttm_bo_device *bdev)
 {
@@ -753,6 +755,7 @@ void radeon_ttm_fini(struct radeon_device *rdev)
 
         if (!rdev->mman.initialized)
                 return;
+        radeon_ttm_debugfs_fini(rdev);
         if (rdev->stollen_vga_memory) {
                 r = radeon_bo_reserve(rdev->stollen_vga_memory, false);
                 if (r == 0) {
@@ -862,12 +865,75 @@ static struct drm_info_list radeon_ttm_debugfs_list[] = {
 #endif
 };
 
+static int radeon_ttm_vram_open(struct inode *inode, struct file *filep)
+{
+        struct radeon_device *rdev = inode->i_private;
+        i_size_write(inode, rdev->mc.mc_vram_size);
+        filep->private_data = inode->i_private;
+        return 0;
+}
+
+static ssize_t radeon_ttm_vram_read(struct file *f, char __user *buf,
+                                    size_t size, loff_t *pos)
+{
+        struct radeon_device *rdev = f->private_data;
+        ssize_t result = 0;
+        int r;
+
+        if (size & 0x3 || *pos & 0x3)
+                return -EINVAL;
+
+        while (size) {
+                unsigned long flags;
+                uint32_t value;
+
+                if (*pos >= rdev->mc.mc_vram_size)
+                        return result;
+
+                spin_lock_irqsave(&rdev->mmio_idx_lock, flags);
+                WREG32(RADEON_MM_INDEX, ((uint32_t)*pos) | 0x80000000);
+                if (rdev->family >= CHIP_CEDAR)
+                        WREG32(EVERGREEN_MM_INDEX_HI, *pos >> 31);
+                value = RREG32(RADEON_MM_DATA);
+                spin_unlock_irqrestore(&rdev->mmio_idx_lock, flags);
+
+                r = put_user(value, (uint32_t *)buf);
+                if (r)
+                        return r;
+
+                result += 4;
+                buf += 4;
+                *pos += 4;
+                size -= 4;
+        }
+
+        return result;
+}
+
+static const struct file_operations radeon_ttm_vram_fops = {
+        .owner = THIS_MODULE,
+        .open = radeon_ttm_vram_open,
+        .read = radeon_ttm_vram_read,
+        .llseek = default_llseek
+};
+
 #endif
 
 static int radeon_ttm_debugfs_init(struct radeon_device *rdev)
 {
 #if defined(CONFIG_DEBUG_FS)
-        unsigned count = ARRAY_SIZE(radeon_ttm_debugfs_list);
+        unsigned count;
+
+        struct drm_minor *minor = rdev->ddev->primary;
+        struct dentry *ent, *root = minor->debugfs_root;
+
+        ent = debugfs_create_file("radeon_vram", S_IFREG | S_IRUGO, root,
+                                  rdev, &radeon_ttm_vram_fops);
+        if (IS_ERR(ent))
+                return PTR_ERR(ent);
+        rdev->mman.vram = ent;
+
+        count = ARRAY_SIZE(radeon_ttm_debugfs_list);
 
 #ifdef CONFIG_SWIOTLB
         if (!swiotlb_nr_tbl())
@@ -880,3 +946,12 @@ static int radeon_ttm_debugfs_init(struct radeon_device *rdev)
         return 0;
 #endif
 }
+
+static void radeon_ttm_debugfs_fini(struct radeon_device *rdev)
+{
+#if defined(CONFIG_DEBUG_FS)
+
+        debugfs_remove(rdev->mman.vram);
+        rdev->mman.vram = NULL;
+#endif
+}