[AVR32] Reserve framebuffer memory in early_parse_fbmem()

With the current strategy of using the bootmem allocator to allocate
or reserve framebuffer memory, there's a slight chance that the
requested area has been taken by the boot allocator bitmap before we
get around to reserving it.

By inserting the framebuffer region as a reserved region as early as
possible, we improve our chances for success and we make the region
visible as a reserved region in dmesg and /proc/iomem without any
extra work.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

1 files changed, 61 insertions, 7 deletions

diff --git a/arch/avr32/kernel/setup.c b/arch/avr32/kernel/setup.c
index d0a35a1b6a66..1682e2d61cf3 100644
--- a/arch/avr32/kernel/setup.c
+++ b/arch/avr32/kernel/setup.c
@@ -191,21 +191,45 @@ find_free_region(const struct resource *mem, resource_size_t size,
         return target;
 }
 
+static int __init
+alloc_reserved_region(resource_size_t *start, resource_size_t size,
+                      resource_size_t align, const char *name)
+{
+        struct resource *mem;
+        resource_size_t target;
+        int ret;
+
+        for (mem = system_ram; mem; mem = mem->sibling) {
+                target = find_free_region(mem, size, align);
+                if (target <= mem->end) {
+                        ret = add_reserved_region(target, target + size - 1,
+                                                  name);
+                        if (!ret)
+                                *start = target;
+                        return ret;
+                }
+        }
+
+        return -ENOMEM;
+}
+
 /*
  * Early framebuffer allocation. Works as follows:
  *   - If fbmem_size is zero, nothing will be allocated or reserved.
  *   - If fbmem_start is zero when setup_bootmem() is called,
- *     fbmem_size bytes will be allocated from the bootmem allocator.
+ *     a block of fbmem_size bytes will be reserved before bootmem
+ *     initialization. It will be aligned to the largest page size
+ *     that fbmem_size is a multiple of.
  *   - If fbmem_start is nonzero, an area of size fbmem_size will be
- *     reserved at the physical address fbmem_start if necessary. If
- *     the area isn't in a memory region known to the kernel, it will
- *     be left alone.
+ *     reserved at the physical address fbmem_start if possible. If
+ *     it collides with other reserved memory, a different block of
+ *     same size will be allocated, just as if fbmem_start was zero.
  *
  * Board-specific code may use these variables to set up platform data
  * for the framebuffer driver if fbmem_size is nonzero.
  */
-static unsigned long __initdata fbmem_start;
-static unsigned long __initdata fbmem_size;
+static resource_size_t __initdata fbmem_start;
+static resource_size_t __initdata fbmem_size;
 
 /*
  * "fbmem=xxx[kKmM]" allocates the specified amount of boot memory for
@@ -219,9 +243,39 @@ static unsigned long __initdata fbmem_size;
  */
 static int __init early_parse_fbmem(char *p)
 {
+        int ret;
+        unsigned long align;
+
         fbmem_size = memparse(p, &p);
-        if (*p == '@')
+        if (*p == '@') {
                 fbmem_start = memparse(p, &p);
+                ret = add_reserved_region(fbmem_start,
+                                          fbmem_start + fbmem_size - 1,
+                                          "Framebuffer");
+                if (ret) {
+                        printk(KERN_WARNING
+                               "Failed to reserve framebuffer memory\n");
+                        fbmem_start = 0;
+                }
+        }
+
+        if (!fbmem_start) {
+                if ((fbmem_size & 0x000fffffUL) == 0)
+                        align = 0x100000;       /* 1 MiB */
+                else if ((fbmem_size & 0x0000ffffUL) == 0)
+                        align = 0x10000;        /* 64 KiB */
+                else
+                        align = 0x1000;         /* 4 KiB */
+
+                ret = alloc_reserved_region(&fbmem_start, fbmem_size,
+                                            align, "Framebuffer");
+                if (ret) {
+                        printk(KERN_WARNING
+                               "Failed to allocate framebuffer memory\n");
+                        fbmem_size = 0;
+                }
+        }
+
         return 0;
 }
 early_param("fbmem", early_parse_fbmem);