From 65422160b21224e6d26641a4c1fa3082c0281488 Mon Sep 17 00:00:00 2001
From: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Date: Mon, 17 Jun 2013 13:32:11 +0300
Subject: [PATCH] fbdev: add FBIOCOPYAREA ioctl

Based on the patch authored by Ali Gholami Rudi at
    https://lkml.org/lkml/2009/7/13/153

Provide an ioctl for userspace applications, but only if this operation
is hardware accelerated (otherwide it does not make any sense).

Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>

bcm2708_fb: Add ioctl for reading gpu memory through dma
---
 drivers/video/fbdev/bcm2708_fb.c | 109 +++++++++++++++++++++++++++++++++++++++
 drivers/video/fbdev/core/fbmem.c |  36 +++++++++++++
 include/uapi/linux/fb.h          |  12 +++++
 3 files changed, 157 insertions(+)

--- a/drivers/video/fbdev/bcm2708_fb.c
+++ b/drivers/video/fbdev/bcm2708_fb.c
@@ -31,8 +31,10 @@
 #include <linux/console.h>
 #include <linux/debugfs.h>
 #include <asm/sizes.h>
+#include <asm/uaccess.h>
 #include <linux/io.h>
 #include <linux/dma-mapping.h>
+#include <linux/cred.h>
 #include <soc/bcm2835/raspberrypi-firmware.h>
 
 //#define BCM2708_FB_DEBUG
@@ -426,6 +428,110 @@ static int bcm2708_fb_pan_display(struct
 	return result;
 }
 
+static void dma_memcpy(struct bcm2708_fb *fb, dma_addr_t dst, dma_addr_t src, int size)
+{
+	int burst_size = (fb->dma_chan == 0) ? 8 : 2;
+	struct bcm2708_dma_cb *cb = fb->cb_base;
+
+	cb->info = BCM2708_DMA_BURST(burst_size) | BCM2708_DMA_S_WIDTH |
+		   BCM2708_DMA_S_INC | BCM2708_DMA_D_WIDTH |
+		   BCM2708_DMA_D_INC;
+	cb->dst = dst;
+	cb->src = src;
+	cb->length = size;
+	cb->stride = 0;
+	cb->pad[0] = 0;
+	cb->pad[1] = 0;
+	cb->next = 0;
+
+	if (size < dma_busy_wait_threshold) {
+		bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
+		bcm_dma_wait_idle(fb->dma_chan_base);
+	} else {
+		void __iomem *dma_chan = fb->dma_chan_base;
+		cb->info |= BCM2708_DMA_INT_EN;
+		bcm_dma_start(fb->dma_chan_base, fb->cb_handle);
+		while (bcm_dma_is_busy(dma_chan)) {
+			wait_event_interruptible(
+				fb->dma_waitq,
+				!bcm_dma_is_busy(dma_chan));
+		}
+		fb->stats.dma_irqs++;
+	}
+	fb->stats.dma_copies++;
+}
+
+#define INTALIAS_NORMAL(x) ((x)&~0xc0000000) // address with no aliases
+#define INTALIAS_L1L2_NONALLOCATING(x) (((x)&~0xc0000000)|0x80000000) // cache coherent but non-allocating in L1 and L2
+
+static long vc_mem_copy(struct bcm2708_fb *fb, unsigned long arg)
+{
+	struct fb_dmacopy ioparam;
+	size_t size = PAGE_SIZE;
+	u32 *buf = NULL;
+	dma_addr_t bus_addr;
+	long rc = 0;
+	size_t offset;
+	struct { u32 base, length; } gpu = {};
+
+	/* restrict this to root user */
+	if (!uid_eq(current_euid(), GLOBAL_ROOT_UID))
+	{
+		rc = -EFAULT;
+		goto out;
+	}
+
+	/* Get the parameter data.
+	 */
+	if (copy_from_user
+	    (&ioparam, (void *)arg, sizeof(ioparam)) != 0) {
+		pr_err("[%s]: failed to copy-from-user\n",
+				__func__);
+		rc = -EFAULT;
+		goto out;
+	}
+
+	rc = rpi_firmware_property(fb->fw,
+				    RPI_FIRMWARE_GET_VC_MEMORY,
+				    &gpu, sizeof(gpu));
+	if (rc != 0 || gpu.base == 0 || gpu.length == 0) {
+		pr_err("[%s]: Unable to determine gpu memory %ld,%x,%x)\n", __func__, rc, gpu.base, gpu.length);
+		return -EFAULT;
+	}
+
+	if (INTALIAS_NORMAL(ioparam.src) < gpu.base || INTALIAS_NORMAL(ioparam.src) >= gpu.base + gpu.length) {
+		pr_err("[%s]: Invalid memory access %x (%x-%x)", __func__, INTALIAS_NORMAL(ioparam.src), gpu.base, gpu.base + gpu.length);
+		return -EFAULT;
+	}
+
+	buf = dma_alloc_coherent(fb->fb.device, PAGE_ALIGN(size), &bus_addr,
+				 GFP_ATOMIC);
+	if (!buf) {
+		pr_err("[%s]: failed to dma_alloc_coherent(%d)\n",
+				__func__, size);
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	for (offset = 0; offset < ioparam.length; offset += size) {
+		size_t remaining = ioparam.length - offset;
+		size_t s = min(size, remaining);
+		unsigned char *p = (unsigned char *)ioparam.src + offset;
+		unsigned char *q = (unsigned char *)ioparam.dst + offset;
+		dma_memcpy(fb, bus_addr, INTALIAS_L1L2_NONALLOCATING((dma_addr_t)p), size);
+		if (copy_to_user(q, buf, s) != 0) {
+			pr_err("[%s]: failed to copy-to-user\n",
+					__func__);
+			rc = -EFAULT;
+			goto out;
+		}
+	}
+out:
+	if (buf)
+		dma_free_coherent(fb->fb.device, PAGE_ALIGN(size), buf, bus_addr);
+	return rc;
+}
+
 static int bcm2708_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
 {
 	struct bcm2708_fb *fb = to_bcm2708(info);
@@ -438,6 +544,9 @@ static int bcm2708_ioctl(struct fb_info
 					    RPI_FIRMWARE_FRAMEBUFFER_SET_VSYNC,
 					    &dummy, sizeof(dummy));
 		break;
+	case FBIODMACOPY:
+		ret = vc_mem_copy(fb, arg);
+		break;
 	default:
 		dev_dbg(info->device, "Unknown ioctl 0x%x\n", cmd);
 		return -ENOTTY;
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1084,6 +1084,31 @@ fb_blank(struct fb_info *info, int blank
 }
 EXPORT_SYMBOL(fb_blank);
 
+static int fb_copyarea_user(struct fb_info *info,
+			    struct fb_copyarea *copy)
+{
+	int ret = 0;
+	if (!lock_fb_info(info))
+		return -ENODEV;
+	if (copy->dx >= info->var.xres ||
+	    copy->sx >= info->var.xres ||
+	    copy->width > info->var.xres ||
+	    copy->dy >= info->var.yres ||
+	    copy->sy >= info->var.yres ||
+	    copy->height > info->var.yres ||
+	    copy->dx + copy->width > info->var.xres ||
+	    copy->sx + copy->width > info->var.xres ||
+	    copy->dy + copy->height > info->var.yres ||
+	    copy->sy + copy->height > info->var.yres) {
+		ret = -EINVAL;
+		goto out;
+	}
+	info->fbops->fb_copyarea(info, copy);
+out:
+	unlock_fb_info(info);
+	return ret;
+}
+
 static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
 			unsigned long arg)
 {
@@ -1094,6 +1119,7 @@ static long do_fb_ioctl(struct fb_info *
 	struct fb_cmap cmap_from;
 	struct fb_cmap_user cmap;
 	struct fb_event event;
+	struct fb_copyarea copy;
 	void __user *argp = (void __user *)arg;
 	long ret = 0;
 
@@ -1211,6 +1237,15 @@ static long do_fb_ioctl(struct fb_info *
 		unlock_fb_info(info);
 		console_unlock();
 		break;
+	case FBIOCOPYAREA:
+		if (info->flags & FBINFO_HWACCEL_COPYAREA) {
+			/* only provide this ioctl if it is accelerated */
+			if (copy_from_user(&copy, argp, sizeof(copy)))
+				return -EFAULT;
+			ret = fb_copyarea_user(info, &copy);
+			break;
+		}
+		/* fall through */
 	default:
 		if (!lock_fb_info(info))
 			return -ENODEV;
@@ -1365,6 +1400,7 @@ static long fb_compat_ioctl(struct file
 	case FBIOPAN_DISPLAY:
 	case FBIOGET_CON2FBMAP:
 	case FBIOPUT_CON2FBMAP:
+	case FBIOCOPYAREA:
 		arg = (unsigned long) compat_ptr(arg);
 	case FBIOBLANK:
 		ret = do_fb_ioctl(info, cmd, arg);
--- a/include/uapi/linux/fb.h
+++ b/include/uapi/linux/fb.h
@@ -34,6 +34,12 @@
 #define FBIOPUT_MODEINFO        0x4617
 #define FBIOGET_DISPINFO        0x4618
 #define FBIO_WAITFORVSYNC	_IOW('F', 0x20, __u32)
+/*
+ * HACK: use 'z' in order not to clash with any other ioctl numbers which might
+ * be concurrently added to the mainline kernel
+ */
+#define FBIOCOPYAREA		_IOW('z', 0x21, struct fb_copyarea)
+#define FBIODMACOPY 		_IOW('z', 0x22, struct fb_dmacopy)
 
 #define FB_TYPE_PACKED_PIXELS		0	/* Packed Pixels	*/
 #define FB_TYPE_PLANES			1	/* Non interleaved planes */
@@ -346,6 +352,12 @@ struct fb_copyarea {
 	__u32 sy;
 };
 
+struct fb_dmacopy {
+	void *dst;
+	__u32 src;
+	__u32 length;
+};
+
 struct fb_fillrect {
 	__u32 dx;	/* screen-relative */
 	__u32 dy;
