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[PATCH 1/3] MIPS: Allow platform specific scratch registers

To: linux-mips@linux-mips.org, ralf@linux-mips.org
Subject: [PATCH 1/3] MIPS: Allow platform specific scratch registers
From: "Jayachandran C" <jchandra@broadcom.com>
Date: Wed, 20 Mar 2013 21:57:04 +0530
Cc: "Jayachandran C" <jchandra@broadcom.com>
In-reply-to: <cover.1363772750.git.jchandra@broadcom.com>
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XLR/XLP COP0 scratch is register 22, sel 0-7. Add a function
c0_kscratch() which returns the scratch register for the platform,
and use the return value while generating TLB handlers.

Setup kscratch_mask to 0xf for XLR/XLP since the config4 register
does not exist. This allows the kernel to allocate scratch registers
0-3 if needed.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
---
 arch/mips/kernel/cpu-probe.c |    1 +
 arch/mips/mm/tlbex.c         |   41 ++++++++++++++++++++++++++---------------
 2 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index d069a19..1d7bfb3 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -1154,6 +1154,7 @@ static inline void cpu_probe_netlogic(struct cpuinfo_mips 
*c, int cpu)
                set_isa(c, MIPS_CPU_ISA_M64R1);
                c->tlbsize = ((read_c0_config1() >> 25) & 0x3f) + 1;
        }
+       c->kscratch_mask = 0xf;
 }
 
 #ifdef CONFIG_64BIT
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 820e661..ca470c6 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -309,6 +309,17 @@ static int check_for_high_segbits __cpuinitdata;
 
 static unsigned int kscratch_used_mask __cpuinitdata;
 
+static inline int __maybe_unused c0_kscratch(void)
+{
+       switch (current_cpu_type()) {
+       case CPU_XLP:
+       case CPU_XLR:
+               return 22;
+       default:
+               return 31;
+       }
+}
+
 static int __cpuinit allocate_kscratch(void)
 {
        int r;
@@ -340,7 +351,7 @@ static struct work_registers __cpuinit 
build_get_work_registers(u32 **p)
 
        if (scratch_reg > 0) {
                /* Save in CPU local C0_KScratch? */
-               UASM_i_MTC0(p, 1, 31, scratch_reg);
+               UASM_i_MTC0(p, 1, c0_kscratch(), scratch_reg);
                r.r1 = K0;
                r.r2 = K1;
                r.r3 = 1;
@@ -389,7 +400,7 @@ static struct work_registers __cpuinit 
build_get_work_registers(u32 **p)
 static void __cpuinit build_restore_work_registers(u32 **p)
 {
        if (scratch_reg > 0) {
-               UASM_i_MFC0(p, 1, 31, scratch_reg);
+               UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
                return;
        }
        /* K0 already points to save area, restore $1 and $2  */
@@ -678,7 +689,7 @@ static __cpuinit void build_restore_pagemask(u32 **p,
                        uasm_il_b(p, r, lid);
                }
                if (scratch_reg > 0)
-                       UASM_i_MFC0(p, 1, 31, scratch_reg);
+                       UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
                else
                        UASM_i_LW(p, 1, scratchpad_offset(0), 0);
        } else {
@@ -821,7 +832,7 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct 
uasm_reloc **r,
 #ifdef CONFIG_MIPS_PGD_C0_CONTEXT
        if (pgd_reg != -1) {
                /* pgd is in pgd_reg */
-               UASM_i_MFC0(p, ptr, 31, pgd_reg);
+               UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
        } else {
                /*
                 * &pgd << 11 stored in CONTEXT [23..63].
@@ -934,7 +945,7 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, 
struct uasm_reloc **r,
 
                if (mode == refill_scratch) {
                        if (scratch_reg > 0)
-                               UASM_i_MFC0(p, 1, 31, scratch_reg);
+                               UASM_i_MFC0(p, 1, c0_kscratch(), scratch_reg);
                        else
                                UASM_i_LW(p, 1, scratchpad_offset(0), 0);
                } else {
@@ -1100,7 +1111,7 @@ struct mips_huge_tlb_info {
 static struct mips_huge_tlb_info __cpuinit
 build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
                               struct uasm_reloc **r, unsigned int tmp,
-                              unsigned int ptr, int c0_scratch)
+                              unsigned int ptr, int c0_scratch_reg)
 {
        struct mips_huge_tlb_info rv;
        unsigned int even, odd;
@@ -1114,12 +1125,12 @@ build_fast_tlb_refill_handler (u32 **p, struct 
uasm_label **l,
                UASM_i_MFC0(p, tmp, C0_BADVADDR);
 
                if (pgd_reg != -1)
-                       UASM_i_MFC0(p, ptr, 31, pgd_reg);
+                       UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
                else
                        UASM_i_MFC0(p, ptr, C0_CONTEXT);
 
-               if (c0_scratch >= 0)
-                       UASM_i_MTC0(p, scratch, 31, c0_scratch);
+               if (c0_scratch_reg >= 0)
+                       UASM_i_MTC0(p, scratch, c0_kscratch(), c0_scratch_reg);
                else
                        UASM_i_SW(p, scratch, scratchpad_offset(0), 0);
 
@@ -1134,14 +1145,14 @@ build_fast_tlb_refill_handler (u32 **p, struct 
uasm_label **l,
                }
        } else {
                if (pgd_reg != -1)
-                       UASM_i_MFC0(p, ptr, 31, pgd_reg);
+                       UASM_i_MFC0(p, ptr, c0_kscratch(), pgd_reg);
                else
                        UASM_i_MFC0(p, ptr, C0_CONTEXT);
 
                UASM_i_MFC0(p, tmp, C0_BADVADDR);
 
-               if (c0_scratch >= 0)
-                       UASM_i_MTC0(p, scratch, 31, c0_scratch);
+               if (c0_scratch_reg >= 0)
+                       UASM_i_MTC0(p, scratch, c0_kscratch(), c0_scratch_reg);
                else
                        UASM_i_SW(p, scratch, scratchpad_offset(0), 0);
 
@@ -1246,8 +1257,8 @@ build_fast_tlb_refill_handler (u32 **p, struct uasm_label 
**l,
        }
        UASM_i_MTC0(p, odd, C0_ENTRYLO1); /* load it */
 
-       if (c0_scratch >= 0) {
-               UASM_i_MFC0(p, scratch, 31, c0_scratch);
+       if (c0_scratch_reg >= 0) {
+               UASM_i_MFC0(p, scratch, c0_kscratch(), c0_scratch_reg);
                build_tlb_write_entry(p, l, r, tlb_random);
                uasm_l_leave(l, *p);
                rv.restore_scratch = 1;
@@ -1494,7 +1505,7 @@ static void __cpuinit build_r4000_setup_pgd(void)
        } else {
                /* PGD in c0_KScratch */
                uasm_i_jr(&p, 31);
-               UASM_i_MTC0(&p, a0, 31, pgd_reg);
+               UASM_i_MTC0(&p, a0, c0_kscratch(), pgd_reg);
        }
        if (p - tlbmiss_handler_setup_pgd > 
ARRAY_SIZE(tlbmiss_handler_setup_pgd))
                panic("tlbmiss_handler_setup_pgd space exceeded");
-- 
1.7.9.5



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