arm: Fix up new cache flush algorithm and replace dcache_*_all() with it

This patch fixes the remaining few bugs in our shiny new cache iteration
by set/way/level algorithm to actually make it work: It makes it start
from cache level 0 (previously it would always start at LoC and be
"done" instantly), fixes up the two shifts that isolate the set bits at
the end (which didn't seem to account for the fact that the first shift
affects the second), and throws an S bit on that last shift so that it
actually affects the conditionals after it.

In addition, also moves the next_level block to the top so that we can
share (and thus eliminate) some code at initialization, and turns the
whole thing into a thrice-instantiated macro to create functions that
fit our existing interface.

Change-Id: I1338a589cbb37d74ea6e7a3d4f67ff827e24edbe
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/183879
Reviewed-by: Stefan Reinauer <reinauer@google.com>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
(cherry picked from commit 6d94f8330191c316fe093ddb5288329453da8a4b)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6932
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

3 files changed, 118 insertions, 126 deletions

diff --git a/payloads/libpayload/arch/arm/Makefile.inc b/payloads/libpayload/arch/arm/Makefile.inc
index 53a52df6aa..0078ffe845 100644
--- a/payloads/libpayload/arch/arm/Makefile.inc
+++ b/payloads/libpayload/arch/arm/Makefile.inc
@@ -35,5 +35,5 @@ libc-y += timer.c coreboot.c util.S
 libc-y += virtual.c
 libc-y += memcpy.S memset.S memmove.S
 libc-y += exception_asm.S exception.c
-libc-y += cache.c
+libc-y += cache.c cpu.S
 libcbfs-$(CONFIG_LP_CBFS) += dummy_media.c
diff --git a/payloads/libpayload/arch/arm/cache.c b/payloads/libpayload/arch/arm/cache.c
index 4c222eab73..defe640654 100644
--- a/payloads/libpayload/arch/arm/cache.c
+++ b/payloads/libpayload/arch/arm/cache.c
@@ -36,21 +36,6 @@
 #include <arch/cache.h>
 #include <arch/virtual.h>
 
-#define bitmask(high, low) ((1UL << (high)) + \
-			((1UL << (high)) - 1) - ((1UL << (low)) - 1))
-
-/* Basic log2() implementation. Note: log2(0) is 0 for our purposes. */
-/* FIXME: src/include/lib.h is difficult to work with due to romcc */
-static unsigned long log2(unsigned long u)
-{
-	int i = 0;
-
-	while (u >>= 1)
-		i++;
-
-	return i;
-}
-
 void tlb_invalidate_all(void)
 {
 	/*
@@ -85,116 +70,6 @@ enum dcache_op {
 	OP_DCIMVAC,
 };
 
-/*
- * Do a dcache operation on entire cache by set/way. This is done for
- * portability because mapping of memory address to cache location is
- * implementation defined (See note on "Requirements for operations by
- * set/way" in arch ref. manual).
- */
-static void dcache_op_set_way(enum dcache_op op)
-{
-	uint32_t ccsidr;
-	unsigned int associativity, num_sets, linesize_bytes;
-	unsigned int set, way;
-	unsigned int level;
-
-	level = (read_csselr() >> 1) & 0x7;
-
-	/*
-	 * dcache must be invalidated by set/way for portability since virtual
-	 * memory mapping is system-defined. The number of sets and
-	 * associativity is given by CCSIDR. We'll use DCISW to invalidate the
-	 * dcache.
-	 */
-	ccsidr = read_ccsidr();
-
-	/* FIXME: rounding up required here? */
-	num_sets = ((ccsidr & bitmask(27, 13)) >> 13) + 1;
-	associativity = ((ccsidr & bitmask(12, 3)) >> 3) + 1;
-	/* FIXME: do we need to use CTR.DminLine here? */
-	linesize_bytes = (1 << ((ccsidr & 0x7) + 2)) * 4;
-
-	dsb();
-
-	/*
-	 * Set/way operations require an interesting bit packing. See section
-	 * B4-35 in the ARMv7 Architecture Reference Manual:
-	 *
-	 * A: Log2(associativity)
-	 * B: L+S
-	 * L: Log2(linesize)
-	 * S: Log2(num_sets)
-	 *
-	 * The bits are packed as follows:
-	 *  31  31-A        B B-1    L L-1   4 3   1 0
-	 * |---|-------------|--------|-------|-----|-|
-	 * |Way|    zeros    |   Set  | zeros |level|0|
-	 * |---|-------------|--------|-------|-----|-|
-	 */
-	for (way = 0; way < associativity; way++) {
-		for (set = 0; set < num_sets; set++) {
-			uint32_t val = 0;
-			val |= way << (32 - log2(associativity));
-			val |= set << log2(linesize_bytes);
-			val |= level << 1;
-			switch(op) {
-			case OP_DCCISW:
-				dccisw(val);
-				break;
-			case OP_DCISW:
-				dcisw(val);
-				break;
-			case OP_DCCSW:
-				dccsw(val);
-				break;
-			default:
-				break;
-			}
-		}
-	}
-	isb();
-}
-
-static void dcache_foreach(enum dcache_op op)
-{
-	uint32_t clidr;
-	int level;
-
-	clidr = read_clidr();
-	for (level = 0; level < 7; level++) {
-		unsigned int ctype = (clidr >> (level * 3)) & 0x7;
-		uint32_t csselr;
-
-		switch(ctype) {
-		case 0x2:
-		case 0x3:
-		case 0x4:
-			csselr = level << 1;
-			write_csselr(csselr);
-			dcache_op_set_way(op);
-			break;
-		default:
-			/* no cache, icache only, or reserved */
-			break;
-		}
-	}
-}
-
-void dcache_clean_all(void)
-{
-	dcache_foreach(OP_DCCSW);
-}
-
-void dcache_clean_invalidate_all(void)
-{
-	dcache_foreach(OP_DCCISW);
-}
-
-void dcache_invalidate_all(void)
-{
-	dcache_foreach(OP_DCISW);
-}
-
 unsigned int dcache_line_bytes(void)
 {
 	uint32_t ccsidr;
diff --git a/payloads/libpayload/arch/arm/cpu.S b/payloads/libpayload/arch/arm/cpu.S
new file mode 100644
index 0000000000..29a19e76df
--- /dev/null
+++ b/payloads/libpayload/arch/arm/cpu.S
@@ -0,0 +1,117 @@
+/*
+ * Optimized assembly for low-level CPU operations on ARMv7 processors.
+ *
+ * Cache flushing code based off sys/arch/arm/arm/cpufunc_asm_armv7.S in NetBSD
+ *
+ * Copyright (c) 2010 Per Odlund <per.odlund@armagedon.se>
+ * Copyright (c) 2014 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <arch/asm.h>
+
+/*
+ * Dcache invalidations by set/way work by passing a [way:sbz:set:sbz:level:0]
+ * bitfield in a register to the appropriate MCR instruction. This algorithm
+ * works by initializing a bitfield with the highest-numbered set and way, and
+ * generating a "set decrement" and a "way decrement". The former just contains
+ * the LSB of the set field, but the latter contains the LSB of the way field
+ * minus the highest valid set field... such that when you subtract it from a
+ * [way:0:level] field you end up with a [way - 1:highest_set:level] field
+ * through the magic of double subtraction. It's quite ingenius, really.
+ * Takes care to only use r0-r3 and ip so it's pefectly ABI-compatible without
+ * needing to write to memory.
+ */
+
+.macro	dcache_apply_all crm
+	dsb
+	mov	r3, #-2			@ initialize level so that we start at 0
+
+1:	@next_level
+	add	r3, r3, #2		@ increment level
+
+	mrc	p15, 1, r0, c0, c0, 1	@ read CLIDR
+	and	ip, r0, #0x07000000	@ narrow to LoC
+	lsr	ip, ip, #23		@ left align LoC (low 4 bits)
+	cmp	r3, ip			@ compare
+	bge	3f @done		@ else fall through (r0 == CLIDR)
+
+	add	r2, r3, r3, lsr #1	@ r2 = (level << 1) * 3 / 2
+	mov	r1, r0, lsr r2		@ r1 = cache type
+	bfc	r1, #3, #28
+	cmp	r1, #2			@ is it data or i&d?
+	blt	1b @next_level		@ nope, skip level
+
+	mcr	p15, 2, r3, c0, c0, 0	@ select cache level
+	isb
+	mrc	p15, 1, r0, c0, c0, 0	@ read CCSIDR
+
+	ubfx	ip, r0, #0, #3		@ get linesize from CCSIDR
+	add	ip, ip, #4		@ apply bias
+	ubfx	r2, r0, #13, #15	@ get numsets - 1 from CCSIDR
+	lsl	r2, r2, ip		@ shift to set position
+	orr	r3, r3, r2		@ merge set into way/set/level
+	mov	r1, #1
+	lsl	r1, r1, ip		@ r1 = set decr
+
+	ubfx	ip, r0, #3, #10		@ get numways - 1 from [to be discarded] CCSIDR
+	clz	r2, ip			@ number of bits to MSB of way
+	lsl	ip, ip, r2		@ shift by that into way position
+	mov	r0, #1
+	lsl	r2, r0, r2		@ r2 now contains the way decr
+	mov	r0, r3 			@ get sets/level (no way yet)
+	orr	r3, r3, ip		@ merge way into way/set/level
+	bfc	r0, #0, #4		@ clear low 4 bits (level) to get numset - 1
+	sub	r2, r2, r0		@ subtract from way decr
+
+	/* r3 = ways/sets/level, r2 = way decr, r1 = set decr, r0 and ip are free */
+2:	mcr	p15, 0, r3, c7, \crm, 2	@ writeback and/or invalidate line
+	cmp	r3, #15			@ are we done with this level (way/set == 0)
+	bls	1b @next_level		@ yes, go to next level
+	lsr	r0, r3, #4		@ clear level bits leaving only way/set bits
+	lsls	r0, r0, #14		@ clear way bits leaving only set bits
+	subne	r3, r3, r1		@ non-zero?, decrement set #
+	subeq	r3, r3, r2		@ zero?, decrement way # and restore set count
+	b	2b
+
+3:	@done
+	mov	r0, #0			@ default back to cache level 0
+	mcr	p15, 2, r0, c0, c0, 0	@ select cache level
+	dsb
+	isb
+	bx	lr
+.endm
+
+ENTRY(dcache_invalidate_all)
+	dcache_apply_all crm=c6
+ENDPROC(dcache_invalidate_all)
+
+ENTRY(dcache_clean_all)
+	dcache_apply_all crm=c10
+ENDPROC(dcache_clean_all)
+
+ENTRY(dcache_clean_invalidate_all)
+	dcache_apply_all crm=c14
+ENDPROC(dcache_clean_invalidate_all)