From a21dea7a0d06cbdfe9a94c88b1ba99425bf2e102 Mon Sep 17 00:00:00 2001
From: "Suren A. Chilingaryan" <csa@suren.me>
Date: Sat, 14 May 2016 01:10:33 +0200
Subject: Allow mapping of arbitrary memory areas

---
 driver/dev.c   | 32 ++++++++++++++++++++++++++++++++
 driver/ioctl.c |  2 +-
 driver/ioctl.h |  1 +
 3 files changed, 34 insertions(+), 1 deletion(-)

(limited to 'driver')

diff --git a/driver/dev.c b/driver/dev.c
index 1292110..75b2516 100644
--- a/driver/dev.c
+++ b/driver/dev.c
@@ -127,6 +127,35 @@ static int pcidriver_mmap_bar(pcidriver_privdata_t *privdata, struct vm_area_str
 #endif /* PCIDRIVER_DUMMY_DEVICE */
 }
 
+
+static int pcidriver_mmap_area(pcidriver_privdata_t *privdata, struct vm_area_struct *vmap)
+{
+    int ret = 0;
+
+    unsigned long vma_size;
+    unsigned long addr = vmap->vm_pgoff;
+
+    mod_info_dbg("Entering mmap_addr\n");
+
+    /* Check sizes */
+    vma_size = (vmap->vm_end - vmap->vm_start);
+
+    if (addr % PAGE_SIZE) {
+	mod_info("mmap addr (0x%lx) is not aligned to page boundary\n", addr);
+        return -EINVAL;
+    }
+
+    ret = remap_pfn_range(vmap, vmap->vm_start, (addr >> PAGE_SHIFT), vma_size, vmap->vm_page_prot);
+
+    if (ret) {
+        mod_info("remap_pfn_range failed\n");
+        return -EAGAIN;
+    }
+
+    return 0;	/* success */
+}
+
+
 /**
  *
  * This function is the entry point for mmap() and calls either pcidriver_mmap_bar
@@ -156,6 +185,9 @@ static int pcidriver_mmap(struct file *filp, struct vm_area_struct *vma)
         }
         ret = pcidriver_mmap_bar(privdata, vma, bar);
         break;
+    case PCIDRIVER_MMAP_AREA:
+	ret = pcidriver_mmap_area(privdata, vma);
+	break;
     case PCIDRIVER_MMAP_KMEM:
         ret = pcidriver_mmap_kmem(privdata, vma);
         break;
diff --git a/driver/ioctl.c b/driver/ioctl.c
index dd7c7a3..33dbbe6 100644
--- a/driver/ioctl.c
+++ b/driver/ioctl.c
@@ -54,7 +54,7 @@
  */
 static int ioctl_mmap_mode(pcidriver_privdata_t *privdata, unsigned long arg)
 {
-    if ((arg != PCIDRIVER_MMAP_PCI) && (arg != PCIDRIVER_MMAP_KMEM))
+    if ((arg != PCIDRIVER_MMAP_PCI) && (arg != PCIDRIVER_MMAP_KMEM) && (arg != PCIDRIVER_MMAP_AREA))
         return -EINVAL;
 
     /* change the mode */
diff --git a/driver/ioctl.h b/driver/ioctl.h
index a102092..7d393a5 100644
--- a/driver/ioctl.h
+++ b/driver/ioctl.h
@@ -18,6 +18,7 @@
 /* mmap mode of the device */
 #define PCIDRIVER_MMAP_PCI		0
 #define PCIDRIVER_MMAP_KMEM 		1
+#define PCIDRIVER_MMAP_AREA		2
 
 /* Direction of a DMA operation */
 #define PCIDRIVER_DMA_BIDIRECTIONAL	0
-- 
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