ARCv2: MMUv4: cache programming model changes

Caveats about cache flush on ARCv2 based cores

- dcache is PIPT so paddr is sufficient for cache maintenance ops (no
  need to setup PTAG reg

- icache is still VIPT but only aliasing configs need PTAG setup

So basically this is departure from MMU-v3 which always need vaddr in
line ops registers (DC_IVDL, DC_FLDL, IC_IVIL) but paddr in DC_PTAG,
IC_PTAG respectively.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 6568977..974ed90 100644 (file)
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -223,7 +223,7 @@ config ARC_CACHE_PAGES
 
 config ARC_CACHE_VIPT_ALIASING
        bool "Support VIPT Aliasing D$"
-       depends on ARC_HAS_DCACHE
+       depends on ARC_HAS_DCACHE && ISA_ARCOMPACT
        default n
 
 endif  #ARC_CACHE

diff --git a/arch/arc/include/asm/arcregs.h b/arch/arc/include/asm/arcregs.h
index bcb08cd..070f588 100644 (file)
--- a/arch/arc/include/asm/arcregs.h
+++ b/arch/arc/include/asm/arcregs.h
@@ -17,6 +17,7 @@
 #define ARC_REG_FP_BCR         0x6B    /* ARCompact: Single-Precision FPU */
 #define ARC_REG_DPFP_BCR       0x6C    /* ARCompact: Dbl Precision FPU */
 #define ARC_REG_FP_V2_BCR      0xc8    /* ARCv2 FPU */
+#define ARC_REG_SLC_BCR                0xce
 #define ARC_REG_DCCM_BCR       0x74    /* DCCM Present + SZ */
 #define ARC_REG_TIMERS_BCR     0x75
 #define ARC_REG_AP_BCR         0x76
@@ -331,7 +332,7 @@ struct cpuinfo_arc_mmu {
 };
 
 struct cpuinfo_arc_cache {
-       unsigned int sz_k:8, line_len:8, assoc:4, ver:4, alias:1, vipt:1, pad:6;
+       unsigned int sz_k:14, line_len:8, assoc:4, ver:4, alias:1, vipt:1;
 };
 
 struct cpuinfo_arc_bpu {
@@ -343,7 +344,7 @@ struct cpuinfo_arc_ccm {
 };
 
 struct cpuinfo_arc {
-       struct cpuinfo_arc_cache icache, dcache;
+       struct cpuinfo_arc_cache icache, dcache, slc;
        struct cpuinfo_arc_mmu mmu;
        struct cpuinfo_arc_bpu bpu;
        struct bcr_identity core;

diff --git a/arch/arc/include/asm/cache.h b/arch/arc/include/asm/cache.h
index 7861255..e54977a 100644 (file)
--- a/arch/arc/include/asm/cache.h
+++ b/arch/arc/include/asm/cache.h
@@ -82,4 +82,7 @@ extern void read_decode_cache_bcr(void);
 #define DC_CTRL_INV_MODE_FLUSH  0x40
 #define DC_CTRL_FLUSH_STATUS    0x100
 
+/*System-level cache (L2 cache) related Auxiliary registers */
+#define ARC_REG_SLC_CFG                0x901
+
 #endif /* _ASM_CACHE_H */

diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index 6fa5f0f..7a898f5 100644 (file)
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -24,6 +24,7 @@
 char *arc_cache_mumbojumbo(int c, char *buf, int len)
 {
        int n = 0;
+       struct cpuinfo_arc_cache *p;
 
 #define PR_CACHE(p, cfg, str)                                          \
        if (!(p)->ver)                                                  \
@@ -39,6 +40,11 @@ char *arc_cache_mumbojumbo(int c, char *buf, int len)
        PR_CACHE(&cpuinfo_arc700[c].icache, CONFIG_ARC_HAS_ICACHE, "I-Cache");
        PR_CACHE(&cpuinfo_arc700[c].dcache, CONFIG_ARC_HAS_DCACHE, "D-Cache");
 
+       p = &cpuinfo_arc700[c].slc;
+       if (p->ver)
+               n += scnprintf(buf + n, len - n,
+                       "SLC\t\t: %uK, %uB Line\n", p->sz_k, p->line_len);
+
        return buf;
 }
 
@@ -49,7 +55,7 @@ char *arc_cache_mumbojumbo(int c, char *buf, int len)
  */
 void read_decode_cache_bcr(void)
 {
-       struct cpuinfo_arc_cache *p_ic, *p_dc;
+       struct cpuinfo_arc_cache *p_ic, *p_dc, *p_slc;
        unsigned int cpu = smp_processor_id();
        struct bcr_cache {
 #ifdef CONFIG_CPU_BIG_ENDIAN
@@ -59,14 +65,29 @@ void read_decode_cache_bcr(void)
 #endif
        } ibcr, dbcr;
 
+       struct bcr_generic sbcr;
+
+       struct bcr_slc_cfg {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+               unsigned int pad:24, way:2, lsz:2, sz:4;
+#else
+               unsigned int sz:4, lsz:2, way:2, pad:24;
+#endif
+       } slc_cfg;
+
        p_ic = &cpuinfo_arc700[cpu].icache;
        READ_BCR(ARC_REG_IC_BCR, ibcr);
 
        if (!ibcr.ver)
                goto dc_chk;
 
-       BUG_ON(ibcr.config != 3);
-       p_ic->assoc = 2;                /* Fixed to 2w set assoc */
+       if (ibcr.ver <= 3) {
+               BUG_ON(ibcr.config != 3);
+               p_ic->assoc = 2;                /* Fixed to 2w set assoc */
+       } else if (ibcr.ver >= 4) {
+               p_ic->assoc = 1 << ibcr.config; /* 1,2,4,8 */
+       }
+
        p_ic->line_len = 8 << ibcr.line_len;
        p_ic->sz_k = 1 << (ibcr.sz - 1);
        p_ic->ver = ibcr.ver;
@@ -78,15 +99,32 @@ dc_chk:
        READ_BCR(ARC_REG_DC_BCR, dbcr);
 
        if (!dbcr.ver)
-               return;
+               goto slc_chk;
+
+       if (dbcr.ver <= 3) {
+               BUG_ON(dbcr.config != 2);
+               p_dc->assoc = 4;                /* Fixed to 4w set assoc */
+               p_dc->vipt = 1;
+               p_dc->alias = p_dc->sz_k/p_dc->assoc/TO_KB(PAGE_SIZE) > 1;
+       } else if (dbcr.ver >= 4) {
+               p_dc->assoc = 1 << dbcr.config; /* 1,2,4,8 */
+               p_dc->vipt = 0;
+               p_dc->alias = 0;                /* PIPT so can't VIPT alias */
+       }
 
-       BUG_ON(dbcr.config != 2);
-       p_dc->assoc = 4;                /* Fixed to 4w set assoc */
        p_dc->line_len = 16 << dbcr.line_len;
        p_dc->sz_k = 1 << (dbcr.sz - 1);
        p_dc->ver = dbcr.ver;
-       p_dc->vipt = 1;
-       p_dc->alias = p_dc->sz_k/p_dc->assoc/TO_KB(PAGE_SIZE) > 1;
+
+slc_chk:
+       p_slc = &cpuinfo_arc700[cpu].slc;
+       READ_BCR(ARC_REG_SLC_BCR, sbcr);
+       if (sbcr.ver) {
+               READ_BCR(ARC_REG_SLC_CFG, slc_cfg);
+               p_slc->ver = sbcr.ver;
+               p_slc->sz_k = 128 << slc_cfg.sz;
+               p_slc->line_len = (slc_cfg.lsz == 0) ? 128 : 64;
+       }
 }
 
 /*
@@ -225,10 +263,53 @@ void __cache_line_loop_v3(unsigned long paddr, unsigned long vaddr,
        }
 }
 
+/*
+ * In HS38x (MMU v4), although icache is VIPT, only paddr is needed for cache
+ * maintenance ops (in IVIL reg), as long as icache doesn't alias.
+ *
+ * For Aliasing icache, vaddr is also needed (in IVIL), while paddr is
+ * specified in PTAG (similar to MMU v3)
+ */
+static inline
+void __cache_line_loop_v4(unsigned long paddr, unsigned long vaddr,
+                         unsigned long sz, const int cacheop)
+{
+       unsigned int aux_cmd;
+       int num_lines;
+       const int full_page_op = __builtin_constant_p(sz) && sz == PAGE_SIZE;
+
+       if (cacheop == OP_INV_IC) {
+               aux_cmd = ARC_REG_IC_IVIL;
+       } else {
+               /* d$ cmd: INV (discard or wback-n-discard) OR FLUSH (wback) */
+               aux_cmd = cacheop & OP_INV ? ARC_REG_DC_IVDL : ARC_REG_DC_FLDL;
+       }
+
+       /* Ensure we properly floor/ceil the non-line aligned/sized requests
+        * and have @paddr - aligned to cache line and integral @num_lines.
+        * This however can be avoided for page sized since:
+        *  -@paddr will be cache-line aligned already (being page aligned)
+        *  -@sz will be integral multiple of line size (being page sized).
+        */
+       if (!full_page_op) {
+               sz += paddr & ~CACHE_LINE_MASK;
+               paddr &= CACHE_LINE_MASK;
+       }
+
+       num_lines = DIV_ROUND_UP(sz, L1_CACHE_BYTES);
+
+       while (num_lines-- > 0) {
+               write_aux_reg(aux_cmd, paddr);
+               paddr += L1_CACHE_BYTES;
+       }
+}
+
 #if (CONFIG_ARC_MMU_VER < 3)
 #define __cache_line_loop      __cache_line_loop_v2
 #elif (CONFIG_ARC_MMU_VER == 3)
 #define __cache_line_loop      __cache_line_loop_v3
+#elif (CONFIG_ARC_MMU_VER > 3)
+#define __cache_line_loop      __cache_line_loop_v4
 #endif
 
 #ifdef CONFIG_ARC_HAS_DCACHE
@@ -669,7 +750,6 @@ void arc_cache_init(void)
 
        if (IS_ENABLED(CONFIG_ARC_HAS_DCACHE)) {
                struct cpuinfo_arc_cache *dc = &cpuinfo_arc700[cpu].dcache;
-               int handled;
 
                if (!dc->ver)
                        panic("cache support enabled but non-existent cache\n");
@@ -678,12 +758,14 @@ void arc_cache_init(void)
                        panic("DCache line [%d] != kernel Config [%d]",
                              dc->line_len, L1_CACHE_BYTES);
 
-               /* check for D-Cache aliasing */
-               handled = IS_ENABLED(CONFIG_ARC_CACHE_VIPT_ALIASING);
+               /* check for D-Cache aliasing on ARCompact: ARCv2 has PIPT */
+               if (is_isa_arcompact()) {
+                       int handled = IS_ENABLED(CONFIG_ARC_CACHE_VIPT_ALIASING);
 
-               if (dc->alias && !handled)
-                       panic("Enable CONFIG_ARC_CACHE_VIPT_ALIASING\n");
-               else if (!dc->alias && handled)
-                       panic("Disable CONFIG_ARC_CACHE_VIPT_ALIASING\n");
+                       if (dc->alias && !handled)
+                               panic("Enable CONFIG_ARC_CACHE_VIPT_ALIASING\n");
+                       else if (!dc->alias && handled)
+                               panic("Disable CONFIG_ARC_CACHE_VIPT_ALIASING\n");
+               }
        }
 }