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From 26a7e2d3d11c23acc6f87414da736c07a3b9cc52 Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Sat, 5 Nov 2016 14:14:43 +0000
Subject: [PATCH] bcm2708_fb: Add ioctl for reading gpu memory through dma
---
drivers/video/fbdev/bcm2708_fb.c | 109 +++++++++++++++++++++++++++++++++++++++
include/uapi/linux/fb.h | 7 +++
2 files changed, 116 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
@@ -429,6 +431,110 @@ 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 | BCM2708_DMA_TDMODE;
+ 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(NULL, 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, (dma_addr_t)buf, 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(NULL, 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);
@@ -441,6 +547,9 @@ 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/include/uapi/linux/fb.h
+++ b/include/uapi/linux/fb.h
@@ -39,6 +39,7 @@
* 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 */
@@ -351,6 +352,12 @@ struct fb_copyarea {
__u32 sy;
};
+struct fb_dmacopy {
+ dma_addr_t dst;
+ dma_addr_t src;
+ __u32 length;
+};
+
struct fb_fillrect {
__u32 dx; /* screen-relative */
__u32 dy;
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