Re: [RFC PATCH 14/19] powerpc: allow ioremap within reserved fake ram regions
From: Grant Likely <hidden>
Date: 2009-11-22 23:37:15
On Sun, Nov 22, 2009 at 3:01 PM, Albert Herranz [off-list ref] w= rote:
quoted hunk ↗ jump to hunk
The Nintendo Wii has two discontiguous RAM memory areas called MEM1 and MEM2. MEM1 starts at 0x00000000 and contains 24MB of 1T-SRAM. MEM2 starts at 0x10000000 and contains 64MB of DDR2 RAM. Between both memory address ranges there is an address space where memory-mapped I/O registers are found. Currently, Linux 32-bit PowerPC does not support RAM in discontiguous memory address spaces. Thus, in order to use both RAM areas, we declare as RAM the range from the start of MEM1 to the end of useable MEM2 and exclude the needed parts with /memreserve/ statements, at the expense of wasting a bit of memory. As a side effect, we need to allow ioremapping RAM areas because the I/O address space sits within the memreserve'd part of the declared RAM region. Note that this is not safe if the region ioremapped is covered by an existing BAT mapping used to map RAM, so this is specifically banned here. Signed-off-by: Albert Herranz <redacted> --- =A0arch/powerpc/mm/pgtable_32.c | =A0 19 ++++++++++++++++--- =A01 files changed, 16 insertions(+), 3 deletions(-)diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c index cb96cb2..ba00cb1 100644 --- a/arch/powerpc/mm/pgtable_32.c +++ b/arch/powerpc/mm/pgtable_32.c@@ -191,9 +191,22 @@ __ioremap_caller(phys_addr_t addr, unsigned long siz=
e, unsigned long flags,
=A0 =A0 =A0 =A0 * Don't allow anybody to remap normal RAM that we're usin=
g.
=A0 =A0 =A0 =A0 * mem_init() sets high_memory so only do the check after =
that.
=A0 =A0 =A0 =A0 */
- =A0 =A0 =A0 if (mem_init_done && (p < virt_to_phys(high_memory))) {
- =A0 =A0 =A0 =A0 =A0 =A0 =A0 printk("__ioremap(): phys addr 0x%llx is RA=M lr %p\n",
- =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(unsigned long long)p, __bui=
ltin_return_address(0));
+ =A0 =A0 =A0 if (mem_init_done && (p < virt_to_phys(high_memory)) +#ifdef CONFIG_WII + =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* On some systems, though, we may want t=
o remap an area
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* declared as normal RAM that we have me=
mreserve'd at the
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* device tree. See wii.dts. + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* But we can't do that safely if we are =
using BATs to map
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* part of that area.
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*/
+ =A0 =A0 =A0 =A0 =A0 && !__map_without_bats
+#endif
+ =A0 =A0 =A0 =A0 =A0 ) {
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 printk(KERN_WARNING
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0"__ioremap(): phys addr 0x%l=lx is RAM lr %p\n",
+ =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(unsigned long long)p, + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0__builtin_return_address=
(0)); This could adversely affect multiplatform kernels. I'd rather get the RAM problem fixed and not hack up common code to work around the hack. g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.