sh: fixed PMB mode refactoring.

This introduces some much overdue chainsawing of the fixed PMB support.
fixed PMB was introduced initially to work around the fact that dynamic
PMB mode was relatively broken, though they were never intended to
converge. The main areas where there are differences are whether the
system is booted in 29-bit mode or 32-bit mode, and whether legacy
mappings are to be preserved. Any system booting in true 32-bit mode will
not care about legacy mappings, so these are roughly decoupled.

Regardless of the entry point, PMB and 32BIT are directly related as far
as the kernel is concerned, so we also switch back to having one select
the other.

With legacy mappings iterated through and applied in the initialization
path it's now possible to finally merge the two implementations and
permit dynamic remapping overtop of remaining entries regardless of
whether boot mappings are crafted by hand or inherited from the boot
loader.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

3 files changed, 67 insertions, 65 deletions

diff --git a/arch/sh/mm/Kconfig b/arch/sh/mm/Kconfig
index 358c860aeb9b..860cd24b4205 100644
--- a/arch/sh/mm/Kconfig
+++ b/arch/sh/mm/Kconfig
@@ -80,30 +80,18 @@ config 32BIT
 	bool
 	default y if CPU_SH5
 
-config PMB_ENABLE
-	bool "Support 32-bit physical addressing through PMB"
-	depends on MMU && EXPERIMENTAL && CPU_SH4A && !CPU_SH4AL_DSP
-	help
-	  If you say Y here, physical addressing will be extended to
-	  32-bits through the SH-4A PMB. If this is not set, legacy
-	  29-bit physical addressing will be used.
-
-choice
-	prompt "PMB handling type"
-	depends on PMB_ENABLE
-	default PMB_FIXED
-
 config PMB
-	bool "PMB"
+	bool "Support 32-bit physical addressing through PMB"
 	depends on MMU && EXPERIMENTAL && CPU_SH4A && !CPU_SH4AL_DSP
+	select 32BIT
 	help
 	  If you say Y here, physical addressing will be extended to
 	  32-bits through the SH-4A PMB. If this is not set, legacy
 	  29-bit physical addressing will be used.
 
-config PMB_FIXED
-	bool "fixed PMB"
-	depends on MMU && EXPERIMENTAL && CPU_SH4A && !CPU_SH4AL_DSP
+config PMB_LEGACY
+	bool "Support legacy boot mappings for PMB"
+	depends on PMB
 	select 32BIT
 	help
 	  If this option is enabled, fixed PMB mappings are inherited
@@ -111,8 +99,6 @@ config PMB_FIXED
 	  management. This is the closest to legacy 29-bit physical mode,
 	  and allows systems to support up to 512MiB of system memory.
 
-endchoice
-
 config X2TLB
 	bool "Enable extended TLB mode"
 	depends on (CPU_SHX2 || CPU_SHX3) && MMU && EXPERIMENTAL
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index 9fa11d655044..edde8bdd681d 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -33,7 +33,7 @@ obj-y				+= $(tlb-y)
 endif
 
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
-obj-$(CONFIG_PMB_ENABLE)	+= pmb.o
+obj-$(CONFIG_PMB)		+= pmb.o
 obj-$(CONFIG_NUMA)		+= numa.o
 
 # Special flags for fault_64.o.  This puts restrictions on the number of
diff --git a/arch/sh/mm/pmb.c b/arch/sh/mm/pmb.c
index 280f6a166035..8f7dbf183fb0 100644
--- a/arch/sh/mm/pmb.c
+++ b/arch/sh/mm/pmb.c
@@ -3,7 +3,7 @@
  *
  * Privileged Space Mapping Buffer (PMB) Support.
  *
- * Copyright (C) 2005, 2006, 2007 Paul Mundt
+ * Copyright (C) 2005 - 2010 Paul Mundt
  *
  * P1/P2 Section mapping definitions from map32.h, which was:
  *
@@ -279,51 +279,12 @@ static void __pmb_unmap(struct pmb_entry *pmbe)
 	} while (pmbe);
 }
 
-#ifdef CONFIG_PMB
-int __uses_jump_to_uncached pmb_init(void)
-{
-	unsigned int i;
-	long size, ret;
-
-	jump_to_uncached();
-
-	/*
-	 * Insert PMB entries for the P1 and P2 areas so that, after
-	 * we've switched the MMU to 32-bit mode, the semantics of P1
-	 * and P2 are the same as in 29-bit mode, e.g.
-	 *
-	 *	P1 - provides a cached window onto physical memory
-	 *	P2 - provides an uncached window onto physical memory
-	 */
-	size = __MEMORY_START + __MEMORY_SIZE;
-
-	ret = pmb_remap(P1SEG, 0x00000000, size, PMB_C);
-	BUG_ON(ret != size);
-
-	ret = pmb_remap(P2SEG, 0x00000000, size, PMB_WT | PMB_UB);
-	BUG_ON(ret != size);
-
-	ctrl_outl(0, PMB_IRMCR);
-
-	/* PMB.SE and UB[7] */
-	ctrl_outl(PASCR_SE | (1 << 7), PMB_PASCR);
-
-	/* Flush out the TLB */
-	i =  ctrl_inl(MMUCR);
-	i |= MMUCR_TI;
-	ctrl_outl(i, MMUCR);
-
-	back_to_cached();
-
-	return 0;
-}
-#else
-int __uses_jump_to_uncached pmb_init(void)
+#ifdef CONFIG_PMB_LEGACY
+static int pmb_apply_legacy_mappings(void)
 {
 	int i;
 	unsigned long addr, data;
-
-	jump_to_uncached();
+	unsigned int applied = 0;
 
 	for (i = 0; i < PMB_ENTRY_MAX; i++) {
 		struct pmb_entry *pmbe;
@@ -357,13 +318,69 @@ int __uses_jump_to_uncached pmb_init(void)
 
 		pmbe = pmb_alloc(vpn, ppn, flags, i);
 		WARN_ON(IS_ERR(pmbe));
+
+		applied++;
+	}
+
+	return (applied == 0);
+}
+#else
+static inline int pmb_apply_legacy_mappings(void)
+{
+	return 1;
+}
+#endif
+
+int __uses_jump_to_uncached pmb_init(void)
+{
+	unsigned int i;
+	unsigned long size, ret;
+
+	jump_to_uncached();
+
+	/*
+	 * Attempt to apply the legacy boot mappings if configured. If
+	 * this is successful then we simply carry on with those and
+	 * don't bother establishing additional memory mappings. Dynamic
+	 * device mappings through pmb_remap() can still be bolted on
+	 * after this.
+	 */
+	ret = pmb_apply_legacy_mappings();
+	if (ret == 0) {
+		back_to_cached();
+		return 0;
 	}
 
+	/*
+	 * Insert PMB entries for the P1 and P2 areas so that, after
+	 * we've switched the MMU to 32-bit mode, the semantics of P1
+	 * and P2 are the same as in 29-bit mode, e.g.
+	 *
+	 *	P1 - provides a cached window onto physical memory
+	 *	P2 - provides an uncached window onto physical memory
+	 */
+	size = (unsigned long)__MEMORY_START + __MEMORY_SIZE;
+
+	ret = pmb_remap(P1SEG, 0x00000000, size, PMB_C);
+	BUG_ON(ret != size);
+
+	ret = pmb_remap(P2SEG, 0x00000000, size, PMB_WT | PMB_UB);
+	BUG_ON(ret != size);
+
+	ctrl_outl(0, PMB_IRMCR);
+
+	/* PMB.SE and UB[7] */
+	ctrl_outl(PASCR_SE | (1 << 7), PMB_PASCR);
+
+	/* Flush out the TLB */
+	i =  ctrl_inl(MMUCR);
+	i |= MMUCR_TI;
+	ctrl_outl(i, MMUCR);
+
 	back_to_cached();
 
 	return 0;
 }
-#endif /* CONFIG_PMB */
 
 static int pmb_seq_show(struct seq_file *file, void *iter)
 {
@@ -462,6 +479,5 @@ static int __init pmb_sysdev_init(void)
 {
 	return sysdev_driver_register(&cpu_sysdev_class, &pmb_sysdev_driver);
 }
-
 subsys_initcall(pmb_sysdev_init);
 #endif