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

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Hi Finn,

thanks for your review!

On 3/06/21 8:23 pm, Finn Thain wrote:
On Wed, 2 Jun 2021, Michael Schmitz 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).

Thanks, this does fix the problem I had with CONFIG_ATARI && CONFIG_ISA.

Signed-off-by: Michael Schmity <schmitzmic@xxxxxxxxx>
Checkpatch points out a typo here.
I noticed :-) Fat-fingered the commit in a hurry (and didn't run checkpatch).

Also, I think this should get a 'Fixes' tag so it will be backported.
I wasn't sure what to use as commit ID to be fixed ... Looks like 84b16b7b0d5c818fadc731a69965dc76dce0c91e is the one to blame. Hmm - I thought that code was older than that...

---
  arch/m68k/include/asm/io_mm.h | 64 +++++++++++++++++++++++++++----------------
  1 file changed, 40 insertions(+), 24 deletions(-)

diff --git a/arch/m68k/include/asm/io_mm.h b/arch/m68k/include/asm/io_mm.h
index d41fa48..2275e54 100644
--- 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 */
I have to wonder whether there is a nice simple definition for MULTI_ISA.

As I understand it, MULTI_ISA means that different byte orders and/or different address translations need to be used in the same kernel, so all that cannot be decided at build time.

As long as there is only a single platform that will use this code (ISA only used on a single platform, and neither Atari IDE nor EtherNEC used), MULTI_ISA is not needed.

If we have Kconfig symbols for 'single platform only', and 'multi-platform ISA use', that might be shorter to write and easier to understand. Geert?

Such a definition would make this file a lot more easily understood. Maybe
that flag could be implemented as a Kconfig symbol. I guess that's out of
scope though.

That Kconfig symbol would best sit in Kconfig.machine but have to be aware of definitions in a number of driver Kconfigs. Haven't tried if that works. But I agree it is out of scope for now.

The question then becomes - should I move the MULTI_ISA definitions out of the Q40 branch and out of the later Amiga Gayle PCMCIA branch to the head of the file and add a comment explaining the rationale? Too much churn for now?


  #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);
There is some trailing whitespace added here that 'git am' complains
about.

Also, I think a 'fallthrough' statement would be better than adding a new
else branch that duplicates the new default case below.

I'm still unsure whether changing the default branch for the sake of fixing Atari behaviour is a sane idea - I was hoping for comments either way.

But if it's changed, you are correct that having the control flow fall through instead of taking a redundant else branch is better.

Essentially, changing that hunk to

 #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);

here (and elsewhere below)?

Cheers,

    Michael



  #endif
-    default: return NULL; /* avoid warnings, just in case */
+    default: return (u8 __iomem *)(addr); /* avoid warnings, just in case */
      }
  }
  static inline u16 __iomem *isa_itw(unsigned long addr)
@@ -151,9 +158,12 @@ static inline u16 __iomem *isa_itw(unsigned long addr)
      case ISA_TYPE_AG: return (u16 __iomem *)AG_ISA_IO_W(addr);
  #endif
  #ifdef CONFIG_ATARI_ROM_ISA
-    case ISA_TYPE_ENEC: return (u16 __iomem *)ENEC_ISA_IO_W(addr);
+    case ISA_TYPE_ENEC: if (addr < 1024)
+				return (u16 __iomem *)ENEC_ISA_IO_W(addr);
+			else
+				return (u16 __iomem *)(addr);
  #endif
-    default: return NULL; /* avoid warnings, just in case */
+    default: return (u16 __iomem *)(addr); /* avoid warnings, just in case */
Same here.

      }
  }
  static inline u32 __iomem *isa_itl(unsigned long addr)
@@ -177,9 +187,12 @@ static inline u8 __iomem *isa_mtb(unsigned long addr)
      case ISA_TYPE_AG: return (u8 __iomem *)addr;
  #endif
  #ifdef CONFIG_ATARI_ROM_ISA
-    case ISA_TYPE_ENEC: return (u8 __iomem *)ENEC_ISA_MEM_B(addr);
+    case ISA_TYPE_ENEC: if (addr < 1024)
+				return (u8 __iomem *)ENEC_ISA_MEM_B(addr);
+			else
+				return (u8 __iomem *)(addr);
  #endif
-    default: return NULL; /* avoid warnings, just in case */
+    default: return (u8 __iomem *)(addr); /* avoid warnings, just in case */
And here.

      }
  }
  static inline u16 __iomem *isa_mtw(unsigned long addr)
@@ -193,9 +206,12 @@ static inline u16 __iomem *isa_mtw(unsigned long addr)
      case ISA_TYPE_AG: return (u16 __iomem *)addr;
  #endif
  #ifdef CONFIG_ATARI_ROM_ISA
-    case ISA_TYPE_ENEC: return (u16 __iomem *)ENEC_ISA_MEM_W(addr);
+    case ISA_TYPE_ENEC: if (addr < 1024)
+				return (u16 __iomem *)ENEC_ISA_MEM_W(addr);
+			else
+				return (u16 __iomem *)(addr);
  #endif
-    default: return NULL; /* avoid warnings, just in case */
+    default: return (u16 __iomem *)(addr); /* avoid warnings, just in case */
And here.

      }
  }
@@ -344,31 +360,31 @@ static inline void isa_delay(void)
   * ROM port ISA and everything else regular ISA for IDE. read,write defined
   * below.
   */
-#define inb(port)	((port) < 1024 ? isa_rom_inb(port) : in_8(port))
-#define inb_p(port)	((port) < 1024 ? isa_rom_inb_p(port) : in_8(port))
-#define inw(port)	((port) < 1024 ? isa_rom_inw(port) : in_le16(port))
-#define inw_p(port)	((port) < 1024 ? isa_rom_inw_p(port) : in_le16(port))
+#define inb(port)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_inb(port) : isa_inb(port))
+#define inb_p(port)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_inb_p(port) : isa_inb_p(port))
+#define inw(port)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_inw(port) : isa_inw(port))
+#define inw_p(port)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_inw_p(port) : isa_inw_p(port))
  #define inl		isa_inl
  #define inl_p		isa_inl_p
-#define outb(val, port) ((port) < 1024 ? isa_rom_outb((val), (port)) : out_8((port), (val)))
-#define outb_p(val, port) ((port) < 1024 ? isa_rom_outb_p((val), (port)) : out_8((port), (val)))
-#define outw(val, port)	((port) < 1024 ? isa_rom_outw((val), (port)) : out_le16((port), (val)))
-#define outw_p(val, port) ((port) < 1024 ? isa_rom_outw_p((val), (port)) : out_le16((port), (val)))
+#define outb(val, port)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_outb((val), (port)) : isa_outb((val), (port)))
+#define outb_p(val, port) (((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_outb_p((val), (port)) : isa_outb_p((val), (port)))
+#define outw(val, port)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_outw((val), (port)) : isa_outw((val), (port)))
+#define outw_p(val, port) (((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_outw_p((val), (port)) : isa_outw_p((val), (port)))
  #define outl		isa_outl
  #define outl_p		isa_outl_p
-#define insb(port, buf, nr) ((port) < 1024 ? isa_rom_insb((port), (buf), (nr)) : isa_insb((port), (buf), (nr)))
-#define insw(port, buf, nr)	((port) < 1024 ? isa_rom_insw((port), (buf), (nr)) : isa_insw((port), (buf), (nr)))
+#define insb(port, buf, nr)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_insb((port), (buf), (nr)) : isa_insb((port), (buf), (nr)))
+#define insw(port, buf, nr)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_insw((port), (buf), (nr)) : isa_insw((port), (buf), (nr)))
  #define insl			isa_insl
-#define outsb(port, buf, nr)	((port) < 1024 ? isa_rom_outsb((port), (buf), (nr)) : isa_outsb((port), (buf), (nr)))
-#define outsw(port, buf, nr)	((port) < 1024 ? isa_rom_outsw((port), (buf), (nr)) : isa_outsw((port), (buf), (nr)))
+#define outsb(port, buf, nr)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_outsb((port), (buf), (nr)) : isa_outsb((port), (buf), (nr)))
+#define outsw(port, buf, nr)	(((port) < 1024 && ISA_TYPE == ISA_TYPE_ENEC) ? isa_rom_outsw((port), (buf), (nr)) : isa_outsw((port), (buf), (nr)))
  #define outsl			isa_outsl
-#define readb(addr) in_8(addr)
-#define writeb(val, addr)	out_8((addr), (val))
-#define readw(addr)		in_le16(addr)
-#define writew(val, addr)	out_le16((addr), (val))
+#define readb   isa_readb
+#define readw   isa_readw
+#define writeb  isa_writeb
+#define writew  isa_writew
  #endif /* CONFIG_ATARI_ROM_ISA */
#define readl(addr) in_le32(addr)




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