Re: [PATCH RFC 1/2] m68k: io_mm.h: conditionalize ISA address translation on Atari

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Hi Michael,

On Wed, Jun 2, 2021 at 7:21 AM Michael Schmitz <schmitzmic@xxxxxxxxx> wrote:
Current io_mm.h uses address translation and ROM port IO primitives when
port addresses are below 1024, and raw untranslated MMIO IO primitives
else when CONFIG_ATARI_ROM_ISA is set. This is done regardless of the
m68k machine type a multi-platform kernel runs on. As a consequence,
the Q40 IDE driver in multiplatform kernels cannot work.
Conversely, the Atari IDE driver uses wrong address translation if a
multiplatform Q40 and Atari kernel does _not_ set CONFIG_ATARI_ROM_ISA.

Replace MMIO by ISA IO primitives for addresses > 1024 (if isa_type
is ISA_TYPE_ENEC), and change the ISA address translation used for
Atari to a no-op for those addresses.

Switch readb()/writeb() and readw()/writew() to their ISA equivalents
also. Change the address translation functions to return the identity
translation if CONFIG_ATARI_ROM_ISA is not defined, and set MULTI_ISA
for kernels where Q40 and Atari are both configured so this can actually
work (isa_type set to Q40 at compile time else).

Signed-off-by: Michael Schmity <schmitzmic@xxxxxxxxx>

--- a/arch/m68k/include/asm/io_mm.h
+++ b/arch/m68k/include/asm/io_mm.h
@@ -52,7 +52,11 @@
 #define Q40_ISA_MEM_B(madr)  (q40_isa_mem_base+1+4*((unsigned long)(madr)))
 #define Q40_ISA_MEM_W(madr)  (q40_isa_mem_base+  4*((unsigned long)(madr)))

+#ifdef CONFIG_ATARI
+#define MULTI_ISA 1
+#else
 #define MULTI_ISA 0
+#endif /* Atari */
 #endif /* Q40 */

 #ifdef CONFIG_AMIGA_PCMCIA
@@ -135,9 +139,12 @@ static inline u8 __iomem *isa_itb(unsigned long addr)
     case ISA_TYPE_AG: return (u8 __iomem *)AG_ISA_IO_B(addr);
 #endif
 #ifdef CONFIG_ATARI_ROM_ISA
-    case ISA_TYPE_ENEC: return (u8 __iomem *)ENEC_ISA_IO_B(addr);
+    case ISA_TYPE_ENEC: if (addr < 1024)
+                               return (u8 __iomem *)ENEC_ISA_IO_B(addr);
+                       else
+                               return (u8 __iomem *)(addr);

While putting a simple return on the same line as the case keyword,
please start the if statement on a new line.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds



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