m68k/atari: Reserve some ST-RAM early on for device buffer use

Based on an original patch from Michael Schmitz:

Because mem_init() is now called before device init, devices that rely on
ST-RAM may find all ST-RAM already allocated to other users by the time
device init happens. In particular, a large initrd RAM disk may use up
enough of ST-RAM to cause atari_stram_alloc() to resort to
__get_dma_pages() allocation.

In the current state of Atari memory management, all of RAM is marked
DMA capable, so __get_dma_pages() may well return RAM that is not in actual
fact DMA capable. Using this for frame buffer or SCSI DMA buffer causes
subtle failure.

The ST-RAM allocator has been changed to allocate memory from a pool of
reserved ST-RAM of configurable size, set aside on ST-RAM init (i.e.
before mem_init()). As long as this pool is not exhausted, allocation of
real ST-RAM can be guaranteed.

Other changes:
  - Replace the custom allocator in the ST-RAM pool by the existing allocator
    in the resource subsystem,
  - Remove mem_init_done and its hook, as memory init is now done before
    device init,
  - Remove /proc/stram, as ST-RAM usage now shows up under /proc/iomem, e.g.

	005f2000-006f1fff : ST-RAM Pool
	  005f2000-0063dfff : atafb
	  0063e000-00641fff : ataflop
	  00642000-00642fff : SCSI
Signed-off-by: Michael Schmitz <schmitz@debian.org>
[Andreas Schwab <schwab@linux-m68k.org>: Use memparse()]
[Geert: Use the resource subsystem instead of a custom allocator]
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/Kconfig.mmu

@@ -372,12 +372,6 @@ config AMIGA_PCMCIA
 	  Include support in the kernel for pcmcia on Amiga 1200 and Amiga
 	  600. If you intend to use pcmcia cards say Y; otherwise say N.
 
-config STRAM_PROC
-	bool "ST-RAM statistics in /proc"
-	depends on ATARI
-	help
-	  Say Y here to report ST-RAM usage statistics in /proc/stram.
-
 config HEARTBEAT
 	bool "Use power LED as a heartbeat" if AMIGA || APOLLO || ATARI || MAC ||Q40
 	default y if !AMIGA && !APOLLO && !ATARI && !MAC && !Q40 && HP300

arch/m68k/include/asm/atari_stram.h

@@ -6,12 +6,11 @@
  */
 
 /* public interface */
-void *atari_stram_alloc(long size, const char *owner);
+void *atari_stram_alloc(unsigned long size, const char *owner);
 void atari_stram_free(void *);
 
 /* functions called internally by other parts of the kernel */
 void atari_stram_init(void);
 void atari_stram_reserve_pages(void *start_mem);
-void atari_stram_mem_init_hook (void);
 
 #endif /*_M68K_ATARI_STRAM_H */

arch/m68k/mm/init_mm.c

@@ -83,11 +83,6 @@ void __init mem_init(void)
 	int initpages = 0;
 	int i;
 
-#ifdef CONFIG_ATARI
-	if (MACH_IS_ATARI)
-		atari_stram_mem_init_hook();
-#endif
-
 	/* this will put all memory onto the freelists */
 	totalram_pages = num_physpages = 0;
 	for_each_online_pgdat(pgdat) {