[coreboot-gerrit] New patch to review for coreboot: acfcba9 rk3288: Add early SRAM mapping

[Patrick Georgi (pgeorgi@google.com)]

Patrick Georgi (pgeorgi at google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9342

-gerrit

commit acfcba96f000243306a1382ccf9d796a0ac45ff7
Author: Julius Werner <jwerner at chromium.org>
Date:   Wed Oct 15 18:50:45 2014 -0700

    rk3288: Add early SRAM mapping
    
    Solving the DACR bug will mean that XN bits suddenly become enforced on
    non-LPAE systems, and we will no longer be able to execute out of a
    region mapped DCACHE_OFF. When we enable the MMU in romstage we are
    still executing out of SRAM, so we would instantly kill ourselves.
    
    Solve this issue by enabling the MMU earlier (in the bootblock) and
    mapping the SRAM regions as DCACHE_WRITETHROUGH. They should really be
    DCACHE_WRITEBACK, but it looks like there might be hardware limitations
    in the Cortex-A12 cache architecture that prevent us from doing so.
    Write-through mappings are equivalent to normal non-cacheable on the A12
    anyway, and by using this attribute we don't need to introduce a new
    DCACHE_OFF_BUT_WITHOUT_XN_BIT type in our API. (Also, using normal
    non-cacheable might still have a slight speed advantage over strongly
    ordered since it should fetch whole cache lines at once if the processor
    finds enough accesses it can combine.)
    
    CQ-DEPEND=CL:223783
    BUG=chrome-os-partner:32118
    TEST=None (depends on follow-up CL)
    
    Change-Id: I1e5127421f82177ca11af892b1539538b379625e
    Signed-off-by: Patrick Georgi <pgeorgi at chromium.org>
    Original-Commit-Id: e7b079f4b6a69449f3c7cc18ef0e1704f2006847
    Original-Change-Id: I53e827d95acc2db909f1251de78d65e295eceaa7
    Original-Signed-off-by: Julius Werner <jwerner at chromium.org>
    Original-Reviewed-on: https://chromium-review.googlesource.com/223782
    Original-Reviewed-by: Aaron Durbin <adurbin at chromium.org>
---
 src/mainboard/google/veyron_pinky/romstage.c | 18 ++++--------------
 src/soc/rockchip/rk3288/bootblock.c          | 11 +++++++++++
 src/soc/rockchip/rk3288/memlayout.ld         |  3 ++-
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/src/mainboard/google/veyron_pinky/romstage.c b/src/mainboard/google/veyron_pinky/romstage.c
index 1d7812b..6f9b9d1 100644
--- a/src/mainboard/google/veyron_pinky/romstage.c
+++ b/src/mainboard/google/veyron_pinky/romstage.c
@@ -64,10 +64,6 @@ void main(void)
 	uint64_t base_time = timestamp_get();
 	start_romstage_time = timestamp_get();
 #endif
-	/* used for MMU and CBMEM setup, in MB */
-	u32 dram_start_mb = (uintptr_t)_dram/MiB;
-	u32 dram_size_mb = CONFIG_DRAM_SIZE_MB;
-	u32 dram_end_mb = dram_start_mb + dram_size_mb;
 
 	console_init();
 
@@ -80,18 +76,12 @@ void main(void)
 #if CONFIG_COLLECT_TIMESTAMPS
 	after_dram_time = timestamp_get();
 #endif
-	mmu_init();
-	/* Device memory below DRAM is uncached. */
-	mmu_config_range(0, dram_start_mb, DCACHE_OFF);
-	/* DRAM is cached. */
-	mmu_config_range(dram_start_mb, dram_size_mb, DCACHE_WRITEBACK);
-	/* A window for DMA is uncached. */
+
+	/* Now that DRAM is up, add mappings for it and DMA coherency buffer. */
+	mmu_config_range((uintptr_t)_dram/MiB,
+			 CONFIG_DRAM_SIZE_MB, DCACHE_WRITEBACK);
 	mmu_config_range((uintptr_t)_dma_coherent/MiB,
 			 _dma_coherent_size/MiB, DCACHE_OFF);
-	/* The space above DRAM is uncached. */
-	if (dram_end_mb < 4096)
-		mmu_config_range(dram_end_mb, 4096 - dram_end_mb, DCACHE_OFF);
-	dcache_mmu_enable();
 
 	cbmem_initialize_empty();
 
diff --git a/src/soc/rockchip/rk3288/bootblock.c b/src/soc/rockchip/rk3288/bootblock.c
index eec3456..b2f5bd9 100644
--- a/src/soc/rockchip/rk3288/bootblock.c
+++ b/src/soc/rockchip/rk3288/bootblock.c
@@ -17,10 +17,12 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include <arch/cache.h>
 #include <arch/io.h>
 #include <bootblock_common.h>
 #include <console/console.h>
 #include <soc/rockchip/rk3288/grf.h>
+#include <symbols.h>
 #include "addressmap.h"
 #include "timer.h"
 #include "clock.h"
@@ -41,4 +43,13 @@ static void bootblock_cpu_init(void)
 	}
 
 	rkclk_init();
+
+	mmu_init();
+	/* Start with a clean slate. */
+	mmu_config_range(0, 4096, DCACHE_OFF);
+	/* SRAM is tightly wedged between registers, need to use subtables. Map
+	 * write-through as equivalent for non-cacheable without XN on A17. */
+	mmu_config_range_kb((uintptr_t)_sram/KiB,
+			    _sram_size/KiB, DCACHE_WRITETHROUGH);
+	dcache_mmu_enable();
 }
diff --git a/src/soc/rockchip/rk3288/memlayout.ld b/src/soc/rockchip/rk3288/memlayout.ld
index 6faec63..2ddb6a6 100644
--- a/src/soc/rockchip/rk3288/memlayout.ld
+++ b/src/soc/rockchip/rk3288/memlayout.ld
@@ -34,7 +34,8 @@ SECTIONS
 
 	SRAM_START(0xFF700000)
 	TTB(0xFF700000, 16K)
-	BOOTBLOCK(0xFF704004, 16K - 4)
+	BOOTBLOCK(0xFF704004, 15K - 4)
+	TTB_SUBTABLES(0xFF707c00, 1K)
 	VBOOT2_WORK(0xFF708000, 16K)
 	OVERLAP_VERSTAGE_ROMSTAGE(0xFF70C000, 40K)
 	PRERAM_CBFS_CACHE(0xFF716000, 4K)