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MIPS: BCM47XX: Slightly clean memory detection 

Patch was tested on devices with 64 MiB and 256 MiB of RAM.
It documents every part nicely and drops this hacky part of code:
max = off | ((128 << 20) - 1);

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: https://patchwork.linux-mips.org/patch/6808/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Rafał Miłecki 2014-04-19 12:49:46 +02:00 committed by Ralf Baechle
parent d8ce75934b
commit 96a8123e5f
1 changed files with 11 additions and 8 deletions
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19
arch/mips/bcm47xx/prom.c
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@ -69,15 +69,18 @@ static __init void prom_init_mem(void)
* BCM47XX uses 128MB for addressing the ram, if the system contains
* less that that amount of ram it remaps the ram more often into the
* available space.
* Accessing memory after 128MB will cause an exception.
* max contains the biggest possible address supported by the platform.
* If the method wants to try something above we assume 128MB ram.
*/
off = (unsigned long)prom_init;
max = off | ((128 << 20) - 1);
for (mem = (1 << 20); mem < (128 << 20); mem += (1 << 20)) {
if ((off + mem) > max) {
mem = (128 << 20);
/* Physical address, without mapping to any kernel segment */
off = CPHYSADDR((unsigned long)prom_init);
/* Accessing memory after 128 MiB will cause an exception */
max = 128 << 20;
for (mem = 1 << 20; mem < max; mem += 1 << 20) {
/* Loop condition may be not enough, off may be over 1 MiB */
if (off + mem >= max) {
mem = max;
printk(KERN_DEBUG "assume 128MB RAM\n");
break;
}