powerpc/mm/32s: add setibat() clearibat() and update_bats()

setibat() and clearibat() allows to manipulate IBATs independently
of DBATs.

update_bats() allows to update bats after init. This is done
with MMU off.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/book3s/32/mmu-hash.h

@@ -92,6 +92,8 @@ typedef struct {
 	unsigned long vdso_base;
 } mm_context_t;
 
+void update_bats(void);
+
 /* patch sites */
 extern s32 patch__hash_page_A0, patch__hash_page_A1, patch__hash_page_A2;
 extern s32 patch__hash_page_B, patch__hash_page_C;

arch/powerpc/kernel/head_32.S

@@ -1096,6 +1096,41 @@ BEGIN_MMU_FTR_SECTION
 END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_HIGH_BATS)
 	blr
 
+_ENTRY(update_bats)
+	lis	r4, 1f@h
+	ori	r4, r4, 1f@l
+	tophys(r4, r4)
+	mfmsr	r6
+	mflr	r7
+	li	r3, MSR_KERNEL & ~(MSR_IR | MSR_DR)
+	rlwinm	r0, r6, 0, ~MSR_RI
+	rlwinm	r0, r0, 0, ~MSR_EE
+	mtmsr	r0
+	mtspr	SPRN_SRR0, r4
+	mtspr	SPRN_SRR1, r3
+	SYNC
+	RFI
+1:	bl	clear_bats
+	lis	r3, BATS@ha
+	addi	r3, r3, BATS@l
+	tophys(r3, r3)
+	LOAD_BAT(0, r3, r4, r5)
+	LOAD_BAT(1, r3, r4, r5)
+	LOAD_BAT(2, r3, r4, r5)
+	LOAD_BAT(3, r3, r4, r5)
+BEGIN_MMU_FTR_SECTION
+	LOAD_BAT(4, r3, r4, r5)
+	LOAD_BAT(5, r3, r4, r5)
+	LOAD_BAT(6, r3, r4, r5)
+	LOAD_BAT(7, r3, r4, r5)
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_HIGH_BATS)
+	li	r3, MSR_KERNEL & ~(MSR_IR | MSR_DR | MSR_RI)
+	mtmsr	r3
+	mtspr	SPRN_SRR0, r7
+	mtspr	SPRN_SRR1, r6
+	SYNC
+	RFI
+
 flush_tlbs:
 	lis	r10, 0x40
 1:	addic.	r10, r10, -0x1000

arch/powerpc/mm/ppc_mmu_32.c

@@ -106,6 +106,38 @@ static unsigned int block_size(unsigned long base, unsigned long top)
 	return min3(max_size, 1U << base_shift, 1U << block_shift);
 }
 
+/*
+ * Set up one of the IBAT (block address translation) register pairs.
+ * The parameters are not checked; in particular size must be a power
+ * of 2 between 128k and 256M.
+ * Only for 603+ ...
+ */
+static void setibat(int index, unsigned long virt, phys_addr_t phys,
+		    unsigned int size, pgprot_t prot)
+{
+	unsigned int bl = (size >> 17) - 1;
+	int wimgxpp;
+	struct ppc_bat *bat = BATS[index];
+	unsigned long flags = pgprot_val(prot);
+
+	if (!cpu_has_feature(CPU_FTR_NEED_COHERENT))
+		flags &= ~_PAGE_COHERENT;
+
+	wimgxpp = (flags & _PAGE_COHERENT) | (_PAGE_EXEC ? BPP_RX : BPP_XX);
+	bat[0].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
+	bat[0].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
+	if (flags & _PAGE_USER)
+		bat[0].batu |= 1;	/* Vp = 1 */
+}
+
+static void clearibat(int index)
+{
+	struct ppc_bat *bat = BATS[index];
+
+	bat[0].batu = 0;
+	bat[0].batl = 0;
+}
+
 unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 {
 	int idx;