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authorAndrew Bresticker <abrestic@chromium.org>2015-02-05 13:31:41 -0800
committerPatrick Georgi <pgeorgi@google.com>2015-04-21 08:12:07 +0200
commit3537e956e1ee2d189876fb47a09b65e96ed3c8f4 (patch)
tree484c9a8b41be11273089bba3cfff6bb285803ac8 /src/arch/mips
parentdf4081e72cda341236350647f96b419e03b9edce (diff)
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mips: Allow memory to be identity mapped in the TLB
Introduce identity_map() function. It takes a memory range and identity maps it entirely in the TLB table, if possible. As a result the virtual and physical address ranges are the same. The function attempts to use as large of a page size as possible for each region in order to conserve TLB entries. BUG=chrome-os-partner:36258 BRANCH=none TEST=Build and boot on Pistachio with the rest of the patches applied. Change-Id: I4d781b04699e069a71c49a0c6ca15c7a6b42a468 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 234d32edfd201019b7a723316a79c932c62ce87e Original-Change-Id: If3e2392b19555cb6dbae8b5559c1b1e53a313637 Original-Signed-off-by: Andrew Bresticker <abrestic@chromium.org> Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/246693 Reviewed-on: http://review.coreboot.org/9815 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Diffstat (limited to 'src/arch/mips')
-rw-r--r--src/arch/mips/Makefile.inc3
-rw-r--r--src/arch/mips/include/arch/cpu.h73
-rw-r--r--src/arch/mips/include/arch/mmu.h59
-rw-r--r--src/arch/mips/mmu.c105
4 files changed, 240 insertions, 0 deletions
diff --git a/src/arch/mips/Makefile.inc b/src/arch/mips/Makefile.inc
index 1016f1f79..358e71ddf 100644
--- a/src/arch/mips/Makefile.inc
+++ b/src/arch/mips/Makefile.inc
@@ -37,6 +37,7 @@ bootblock-y += boot.c
bootblock-y += bootblock.S
bootblock-y += bootblock_simple.c
bootblock-y += cache.c
+bootblock-y += mmu.c
bootblock-y += stages.c
bootblock-y += ../../lib/memcpy.c
bootblock-y += ../../lib/memmove.c
@@ -63,6 +64,7 @@ ifeq ($(CONFIG_ARCH_ROMSTAGE_MIPS),y)
romstage-y += boot.c
romstage-$(CONFIG_EARLY_CONSOLE) += early_console.c
romstage-y += cache.c
+romstage-y += mmu.c
romstage-y += stages.c
romstage-y += ../../lib/memcpy.c
romstage-y += ../../lib/memmove.c
@@ -83,6 +85,7 @@ ifeq ($(CONFIG_ARCH_RAMSTAGE_MIPS),y)
ramstage-y += ashldi3.c
ramstage-y += boot.c
ramstage-y += cache.c
+ramstage-y += mmu.c
ramstage-y += stages.c
ramstage-y += tables.c
ramstage-y += ../../lib/memcpy.c
diff --git a/src/arch/mips/include/arch/cpu.h b/src/arch/mips/include/arch/cpu.h
index 4f4c376ee..957e427e7 100644
--- a/src/arch/mips/include/arch/cpu.h
+++ b/src/arch/mips/include/arch/cpu.h
@@ -79,13 +79,86 @@ do { \
} while (0)
/* Shortcuts to access various internal registers, keep adding as needed. */
+#define read_c0_index() __read_32bit_c0_register($0, 0)
+#define write_c0_index(val) __write_32bit_c0_register($0, 0, (val))
+
+#define read_c0_entrylo0() __read_32bit_c0_register($2, 0)
+#define write_c0_entrylo0(val) __write_32bit_c0_register($2, 0, (val))
+
+#define read_c0_entrylo1() __read_32bit_c0_register($3, 0)
+#define write_c0_entrylo1(val) __write_32bit_c0_register($3, 0, (val))
+
+#define read_c0_pagemask() __read_32bit_c0_register($5, 0)
+#define write_c0_pagemask(val) __write_32bit_c0_register($5, 0, (val))
+
+#define read_c0_wired() __read_32bit_c0_register($6, 0)
+#define write_c0_wired(val) __write_32bit_c0_register($6, 0, (val))
+
#define read_c0_count() __read_32bit_c0_register($9, 0)
#define write_c0_count(val) __write_32bit_c0_register($9, 0, (val))
+#define read_c0_entryhi() __read_32bit_c0_register($10, 0)
+#define write_c0_entryhi(val) __write_32bit_c0_register($10, 0, (val))
+
#define read_c0_cause() __read_32bit_c0_register($13, 0)
#define write_c0_cause(val) __write_32bit_c0_register($13, 0, (val))
+#define read_c0_config1() __read_32bit_c0_register($16, 1)
+#define write_c0_config1(val) __write_32bit_c0_register($16, 1, (val))
+
+#define C0_ENTRYLO_PFN_SHIFT 6
+#define C0_ENTRYLO_WB (0x3 << 3) /* Cacheable, write-back, non-coherent */
+#define C0_ENTRYLO_D (0x1 << 2) /* Writeable */
+#define C0_ENTRYLO_V (0x1 << 1) /* Valid */
+#define C0_ENTRYLO_G (0x1 << 0) /* Global */
+
+#define C0_PAGEMASK_SHIFT 13
+#define C0_PAGEMASK_MASK 0xffff
+
+#define C0_WIRED_MASK 0x3f
+
#define C0_CAUSE_DC (1 << 27)
+
+#define C0_CONFIG1_MMUSIZE_SHIFT 25
+#define C0_CONFIG1_MMUSIZE_MASK 0x3f
+
+/* Hazard handling */
+static inline void __nop(void)
+{
+ __asm__ __volatile__("nop");
+}
+
+static inline void __ssnop(void)
+{
+ __asm__ __volatile__("sll\t$0, $0, 1");
+}
+
+#define mtc0_tlbw_hazard() \
+do { \
+ __nop(); \
+ __nop(); \
+} while (0)
+
+#define tlbw_use_hazard() \
+do { \
+ __nop(); \
+ __nop(); \
+ __nop(); \
+} while (0)
+
+#define tlb_probe_hazard() \
+do { \
+ __nop(); \
+ __nop(); \
+ __nop(); \
+} while (0)
+
+#define back_to_back_c0_hazard() \
+do { \
+ __ssnop(); \
+ __ssnop(); \
+ __ssnop(); \
+} while (0)
/**************************************************************************/
#endif /* __MIPS_ARCH_CPU_H */
diff --git a/src/arch/mips/include/arch/mmu.h b/src/arch/mips/include/arch/mmu.h
new file mode 100644
index 000000000..27385f81e
--- /dev/null
+++ b/src/arch/mips/include/arch/mmu.h
@@ -0,0 +1,59 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __MIPS_ARCH_MMU_H
+#define __MIPS_ARCH_MMU_H
+
+#include <arch/cpu.h>
+#include <stddef.h>
+#include <stdint.h>
+
+static inline void tlb_write_indexed(void)
+{
+ __asm__ __volatile__(
+ ".set noreorder\n\t"
+ "tlbwi\n\t"
+ ".set reorder");
+}
+
+static inline uint32_t get_max_pagesize(void)
+{
+ uint32_t max_pgsize;
+
+ write_c0_pagemask(C0_PAGEMASK_MASK << C0_PAGEMASK_SHIFT);
+ back_to_back_c0_hazard();
+ max_pgsize = (((read_c0_pagemask() >> C0_PAGEMASK_SHIFT) &
+ C0_PAGEMASK_MASK) + 1) * 4 * KiB;
+
+ return max_pgsize;
+}
+
+static inline uint32_t get_tlb_size(void)
+{
+ uint32_t tlbsize;
+
+ tlbsize = ((read_c0_config1() >> C0_CONFIG1_MMUSIZE_SHIFT) &
+ C0_CONFIG1_MMUSIZE_MASK) + 1;
+
+ return tlbsize;
+}
+
+int identity_map(uint32_t start, size_t len);
+
+#endif /* __MIPS_ARCH_MMU_H */
diff --git a/src/arch/mips/mmu.c b/src/arch/mips/mmu.c
new file mode 100644
index 000000000..f6944ddad
--- /dev/null
+++ b/src/arch/mips/mmu.c
@@ -0,0 +1,105 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#include <arch/cpu.h>
+#include <arch/mmu.h>
+#include <console/console.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#define MIN_PAGE_SIZE (4 * KiB)
+
+static int add_wired_tlb_entry(uint32_t entrylo0, uint32_t entrylo1,
+ uint32_t entryhi, uint32_t pgsize)
+{
+ uint32_t tlbindex;
+
+ tlbindex = read_c0_wired();
+ if (tlbindex >= get_tlb_size() || tlbindex >= C0_WIRED_MASK) {
+ printk(BIOS_ERR, "Ran out of TLB entries\n");
+ return -1;
+ }
+ write_c0_wired(tlbindex + 1);
+ write_c0_index(tlbindex);
+ write_c0_pagemask(((pgsize / MIN_PAGE_SIZE) - 1) << C0_PAGEMASK_SHIFT);
+ write_c0_entryhi(entryhi);
+ write_c0_entrylo0(entrylo0);
+ write_c0_entrylo1(entrylo1);
+ mtc0_tlbw_hazard();
+ tlb_write_indexed();
+ tlbw_use_hazard();
+
+ return 0;
+}
+
+static uint32_t pick_pagesize(uint32_t start, uint32_t len)
+{
+ uint32_t pgsize, max_pgsize;
+
+ max_pgsize = get_max_pagesize();
+ for (pgsize = max_pgsize;
+ pgsize >= MIN_PAGE_SIZE;
+ pgsize = pgsize / 4) {
+ /*
+ * Each TLB entry maps a pair of virtual pages. To avoid
+ * aliasing, pick the largest page size that is at most
+ * half the size of the region we're trying to map.
+ */
+ if (IS_ALIGNED(start, 2 * pgsize) && (2 * pgsize <= len))
+ break;
+ }
+
+ return pgsize;
+}
+
+/*
+ * Identity map the memory from [start,start+len] in the TLB using the
+ * largest suitable page size so as to conserve TLB entries.
+ */
+int identity_map(uint32_t start, size_t len)
+{
+ uint32_t pgsize, pfn, entryhi, entrylo0, entrylo1;
+
+ while (len > 0) {
+ pgsize = pick_pagesize(start, len);
+ entryhi = start;
+ pfn = start >> 12;
+ entrylo0 = (pfn << C0_ENTRYLO_PFN_SHIFT) | C0_ENTRYLO_WB |
+ C0_ENTRYLO_D | C0_ENTRYLO_V | C0_ENTRYLO_G;
+ start += pgsize;
+ len -= MIN(len, pgsize);
+ if (len >= pgsize) {
+ pfn = start >> 12;
+ entrylo1 = (pfn << C0_ENTRYLO_PFN_SHIFT) |
+ C0_ENTRYLO_WB | C0_ENTRYLO_D | C0_ENTRYLO_V |
+ C0_ENTRYLO_G;
+ start += pgsize;
+ len -= MIN(len, pgsize);
+ } else {
+ entrylo1 = 0;
+ }
+ if (add_wired_tlb_entry(entrylo0, entrylo1, entryhi, pgsize))
+ return -1;
+ }
+
+ return 0;
+}