#include <asm/cachectl.h>
#include <asm/setup.h>
-
-#ifdef CONFIG_ARC_HAS_ICACHE
-static void __ic_line_inv_no_alias(unsigned long, int);
-static void __ic_line_inv_2_alias(unsigned long, int);
-static void __ic_line_inv_4_alias(unsigned long, int);
-
-/* Holds the ptr to flush routine, dependign on size due to aliasing issues */
-static void (*___flush_icache_rtn) (unsigned long, int);
-#endif
-
char *arc_cache_mumbojumbo(int cpu_id, char *buf, int len)
{
int n = 0;
}
#endif
-
- /*
- * if Cache way size is <= page size then no aliasing exhibited
- * otherwise ratio determines num of aliases.
- * e.g. 32K I$, 2 way set assoc, 8k pg size
- * way-sz = 32k/2 = 16k
- * way-pg-ratio = 16k/8k = 2, so 2 aliases possible
- * (meaning 1 line could be in 2 possible locations).
- */
- way_pg_ratio = ic->sz / ARC_ICACHE_WAYS / PAGE_SIZE;
- switch (way_pg_ratio) {
- case 0:
- case 1:
- ___flush_icache_rtn = __ic_line_inv_no_alias;
- break;
- case 2:
- ___flush_icache_rtn = __ic_line_inv_2_alias;
- break;
- case 4:
- ___flush_icache_rtn = __ic_line_inv_4_alias;
- break;
- default:
- panic("Unsupported I-Cache Sz\n");
- }
#endif
/* Enable/disable I-Cache */
/*
* I-Cache Aliasing in ARC700 VIPT caches
*
- * For fetching code from I$, ARC700 uses vaddr (embedded in program code)
- * to "index" into SET of cache-line and paddr from MMU to match the TAG
- * in the WAYS of SET.
- *
- * However the CDU iterface (to flush/inv) lines from software, only takes
- * paddr (to have simpler hardware interface). For simpler cases, using paddr
- * alone suffices.
- * e.g. 2-way-set-assoc, 16K I$ (8k MMU pg sz, 32b cache line size):
- * way_sz = cache_sz / num_ways = 16k/2 = 8k
- * num_sets = way_sz / line_sz = 8k/32 = 256 => 8 bits
- * Ignoring the bottom 5 bits corresp to the off within a 32b cacheline,
- * bits req for calc set-index = bits 12:5 (0 based). Since this range fits
- * inside the bottom 13 bits of paddr, which are same for vaddr and paddr
- * (with 8k pg sz), paddr alone can be safely used by CDU to unambigously
- * locate a cache-line.
+ * ARC VIPT I-cache uses vaddr to index into cache and paddr to match the tag.
+ * The orig Cache Management Module "CDU" only required paddr to invalidate a
+ * certain line since it sufficed as index in Non-Aliasing VIPT cache-geometry.
+ * Infact for distinct V1,V2,P: all of {V1-P},{V2-P},{P-P} would end up fetching
+ * the exact same line.
*
- * However for a difft sized cache, say 32k I$, above math yields need
- * for 14 bits of vaddr to locate a cache line, which can't be provided by
- * paddr, since the bit 13 (0 based) might differ between the two.
- *
- * This lack of extra bits needed for correct line addressing, defines the
- * classical problem of Cache aliasing with VIPT architectures
- * num_aliases = 1 << extra_bits
- * e.g. 2-way-set-assoc, 32K I$ with 8k MMU pg sz => 2 aliases
- * 2-way-set-assoc, 64K I$ with 8k MMU pg sz => 4 aliases
- * 2-way-set-assoc, 16K I$ with 8k MMU pg sz => NO aliases
+ * However for larger Caches (way-size > page-size) - i.e. in Aliasing config,
+ * paddr alone could not be used to correctly index the cache.
*
* ------------------
* MMU v1/v2 (Fixed Page Size 8k)
* ------------------
* The solution was to provide CDU with these additonal vaddr bits. These
- * would be bits [x:13], x would depend on cache-geom.
+ * would be bits [x:13], x would depend on cache-geometry, 13 comes from
+ * standard page size of 8k.
* H/w folks chose [17:13] to be a future safe range, and moreso these 5 bits
* of vaddr could easily be "stuffed" in the paddr as bits [4:0] since the
* orig 5 bits of paddr were anyways ignored by CDU line ops, as they
* represent the offset within cache-line. The adv of using this "clumsy"
- * interface for additional info was no new reg was needed in CDU.
+ * interface for additional info was no new reg was needed in CDU programming
+ * model.
*
* 17:13 represented the max num of bits passable, actual bits needed were
* fewer, based on the num-of-aliases possible.
* -for 2 alias possibility, only bit 13 needed (32K cache)
* -for 4 alias possibility, bits 14:13 needed (64K cache)
*
- * Since vaddr was not available for all instances of I$ flush req by core
- * kernel, the only safe way (non-optimal though) was to kill all possible
- * lines which could represent an alias (even if they didnt represent one
- * in execution).
- * e.g. for 64K I$, 4 aliases possible, so we did
- * flush start
- * flush start | 0x01
- * flush start | 0x2
- * flush start | 0x3
- *
- * The penalty was invoking the operation itself, since tag match is anyways
- * paddr based, a line which didn't represent an alias would not match the
- * paddr, hence wont be killed
- *
- * Note that aliasing concerns are independent of line-sz for a given cache
- * geometry (size + set_assoc) because the extra bits required by line-sz are
- * reduced from the set calc.
- * e.g. 2-way-set-assoc, 32K I$ with 8k MMU pg sz and using math above
- * 32b line-sz: 9 bits set-index-calc, 5 bits offset-in-line => 1 extra bit
- * 64b line-sz: 8 bits set-index-calc, 6 bits offset-in-line => 1 extra bit
- *
* ------------------
* MMU v3
* ------------------
- * This ver of MMU supports var page sizes (1k-16k) - Linux will support
- * 8k (default), 16k and 4k.
+ * This ver of MMU supports variable page sizes (1k-16k): although Linux will
+ * only support 8k (default), 16k and 4k.
* However from hardware perspective, smaller page sizes aggrevate aliasing
* meaning more vaddr bits needed to disambiguate the cache-line-op ;
* the existing scheme of piggybacking won't work for certain configurations.
*/
/***********************************************************
- * Machine specific helpers for per line I-Cache invalidate.
- * 3 routines to accpunt for 1, 2, 4 aliases possible
- */
-
-static void __ic_line_inv_no_alias(unsigned long start, int num_lines)
-{
- while (num_lines-- > 0) {
-#if (CONFIG_ARC_MMU_VER > 2)
- write_aux_reg(ARC_REG_IC_PTAG, start);
-#endif
- write_aux_reg(ARC_REG_IC_IVIL, start);
- start += ARC_ICACHE_LINE_LEN;
- }
-}
-
-static void __ic_line_inv_2_alias(unsigned long start, int num_lines)
-{
- while (num_lines-- > 0) {
-
-#if (CONFIG_ARC_MMU_VER > 2)
- /*
- * MMU v3, CDU prog model (for line ops) now uses a new IC_PTAG
- * reg to pass the "tag" bits and existing IVIL reg only looks
- * at bits relevant for "index" (details above)
- * Programming Notes:
- * -when writing tag to PTAG reg, bit chopping can be avoided,
- * CDU ignores non-tag bits.
- * -Ideally "index" must be computed from vaddr, but it is not
- * avail in these rtns. So to be safe, we kill the lines in all
- * possible indexes corresp to num of aliases possible for
- * given cache config.
- */
- write_aux_reg(ARC_REG_IC_PTAG, start);
- write_aux_reg(ARC_REG_IC_IVIL,
- start & ~(0x1 << PAGE_SHIFT));
- write_aux_reg(ARC_REG_IC_IVIL, start | (0x1 << PAGE_SHIFT));
-#else
- write_aux_reg(ARC_REG_IC_IVIL, start);
- write_aux_reg(ARC_REG_IC_IVIL, start | 0x01);
-#endif
- start += ARC_ICACHE_LINE_LEN;
- }
-}
-
-static void __ic_line_inv_4_alias(unsigned long start, int num_lines)
-{
- while (num_lines-- > 0) {
-
-#if (CONFIG_ARC_MMU_VER > 2)
- write_aux_reg(ARC_REG_IC_PTAG, start);
-
- write_aux_reg(ARC_REG_IC_IVIL,
- start & ~(0x3 << PAGE_SHIFT));
- write_aux_reg(ARC_REG_IC_IVIL,
- start & ~(0x2 << PAGE_SHIFT));
- write_aux_reg(ARC_REG_IC_IVIL,
- start & ~(0x1 << PAGE_SHIFT));
- write_aux_reg(ARC_REG_IC_IVIL, start | (0x3 << PAGE_SHIFT));
-#else
- write_aux_reg(ARC_REG_IC_IVIL, start);
- write_aux_reg(ARC_REG_IC_IVIL, start | 0x01);
- write_aux_reg(ARC_REG_IC_IVIL, start | 0x02);
- write_aux_reg(ARC_REG_IC_IVIL, start | 0x03);
-#endif
- start += ARC_ICACHE_LINE_LEN;
- }
-}
-
-static void __ic_line_inv(unsigned long start, unsigned long sz)
-{
- unsigned long flags;
- int num_lines, slack;
-
- /*
- * Ensure we properly floor/ceil the non-line aligned/sized requests
- * and have @start - aligned to cache line, and integral @num_lines
- * However page sized flushes can be compile time optimised.
- * -@start will be cache-line aligned already (being page aligned)
- * -@sz will be integral multiple of line size (being page sized).
- */
- if (!(__builtin_constant_p(sz) && sz == PAGE_SIZE)) {
- slack = start & ~ICACHE_LINE_MASK;
- sz += slack;
- start -= slack;
- }
-
- num_lines = DIV_ROUND_UP(sz, ARC_ICACHE_LINE_LEN);
-
- local_irq_save(flags);
- (*___flush_icache_rtn) (start, num_lines);
- local_irq_restore(flags);
-}
-
-/* Unlike routines above, having vaddr for flush op (along with paddr),
- * prevents the need to speculatively kill the lines in multiple sets
- * based on ratio of way_sz : pg_sz
+ * Machine specific helper for per line I-Cache invalidate.
*/
-static void __ic_line_inv_vaddr(unsigned long phy_start,
- unsigned long vaddr, unsigned long sz)
+static void __ic_line_inv_vaddr(unsigned long phy_start, unsigned long vaddr,
+ unsigned long sz)
{
unsigned long flags;
int num_lines, slack;
write_aux_reg(ARC_REG_IC_IVIL, vaddr);
vaddr += ARC_ICACHE_LINE_LEN;
#else
- /* this paddr contains vaddrs bits as needed */
+ /* paddr contains stuffed vaddrs bits */
write_aux_reg(ARC_REG_IC_IVIL, addr);
#endif
addr += ARC_ICACHE_LINE_LEN;
#else
-#define __ic_line_inv(start, sz)
#define __ic_line_inv_vaddr(pstart, vstart, sz)
#endif /* CONFIG_ARC_HAS_ICACHE */
projects / kernel / kernel-generic.git / commitdiff