On Aug 12, 2008, at 10:03 PM, Grant Likely wrote:
+/**
+ * ioremap_early - Allow large persistant IO regions to be mapped
early.
+ * @addr: physical address of region
+ * @size: size of region
+ *
+ * This routine uses setbat() to set up IO ranges before the MMU is
+ * fully configured.
+ *
+ * This routine can be called really early, before MMU_init() is
called. It
+ * is useful for setting up early debug output consoles and
frequently
+ * accessed IO regions, like the internally memory mapped registers
(IMMR)
+ * in an SoC. Ranges mapped with this function persist even after
MMU_init()
+ * is called and the MMU is turned on 'for real.'
+ *
+ * The region mapped is large (minimum size of 128k) and virtual
mapping must
+ * be aligned against this boundary. Therefore, to avoid
fragmentation all
+ * calls to ioremap_early() are best made before any calls to ioremap
+ * for smaller regions.
+ */
+void __iomem * __init
+ioremap_early(phys_addr_t addr, unsigned long size)
+{
+ unsigned long v, p;
+ int i;
+
+ /* Be loud and annoying if someone calls this too late.
+ * No need to crash the kernel though */
+ WARN_ON(mem_init_done);
+ if (mem_init_done)
+ return NULL;
+
+ /* Make sure request is sane */
+ if (size == 0)
+ return NULL;
+
+ /* If the region is already block mapped, then there is nothing
+ * to do; just return the mapped address */
+ v = p_mapped_by_bats(addr);
+ if (v)
+ return (void __iomem *)v;
+
+ /* Adjust size to reflect aligned region */
+ p = _ALIGN_DOWN(addr, 128 << 10); /* BATs align on 128k boundaries
*/
+ size = ALIGN(addr - p + size, 128 << 10);
+
+ /* Allocate the aligned virtual base address. ALIGN_DOWN is used
+ * to ensure no overlaps occur with normal 4k ioremaps. */
+ v = ioremap_bot = _ALIGN_DOWN(ioremap_bot, 128 << 10) - size;
+
+ /* Set up a BAT for this IO region */
+ i = loadbat(v, p, size, _PAGE_IO);
what happens if we run out of bats?
does this actually build on any non-BAT based ppc32 system?
+ if (i < 0)
+ return NULL;
+
+ return (void __iomem *) (v + (addr - p));
+}
+
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