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-rw-r--r--arch/arc/include/asm/cache.h2
-rw-r--r--arch/arc/mm/cache.c20
2 files changed, 19 insertions, 3 deletions
diff --git a/arch/arc/include/asm/cache.h b/arch/arc/include/asm/cache.h
index ff7d3232764a..f393b663413e 100644
--- a/arch/arc/include/asm/cache.h
+++ b/arch/arc/include/asm/cache.h
@@ -113,7 +113,9 @@ extern unsigned long perip_base, perip_end;
/* IO coherency related Auxiliary registers */
#define ARC_REG_IO_COH_ENABLE 0x500
+#define ARC_IO_COH_ENABLE_BIT BIT(0)
#define ARC_REG_IO_COH_PARTIAL 0x501
+#define ARC_IO_COH_PARTIAL_BIT BIT(0)
#define ARC_REG_IO_COH_AP0_BASE 0x508
#define ARC_REG_IO_COH_AP0_SIZE 0x509
diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index f2701c13a66b..cf9619d4efb4 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -1145,6 +1145,20 @@ noinline void __init arc_ioc_setup(void)
unsigned int ioc_base, mem_sz;
/*
+ * If IOC was already enabled (due to bootloader) it technically needs to
+ * be reconfigured with aperture base,size corresponding to Linux memory map
+ * which will certainly be different than uboot's. But disabling and
+ * reenabling IOC when DMA might be potentially active is tricky business.
+ * To avoid random memory issues later, just panic here and ask user to
+ * upgrade bootloader to one which doesn't enable IOC
+ */
+ if (read_aux_reg(ARC_REG_IO_COH_ENABLE) & ARC_IO_COH_ENABLE_BIT)
+ panic("IOC already enabled, please upgrade bootloader!\n");
+
+ if (!ioc_enable)
+ return;
+
+ /*
* As for today we don't support both IOC and ZONE_HIGHMEM enabled
* simultaneously. This happens because as of today IOC aperture covers
* only ZONE_NORMAL (low mem) and any dma transactions outside this
@@ -1187,8 +1201,8 @@ noinline void __init arc_ioc_setup(void)
panic("IOC Aperture start must be aligned to the size of the aperture");
write_aux_reg(ARC_REG_IO_COH_AP0_BASE, ioc_base >> 12);
- write_aux_reg(ARC_REG_IO_COH_PARTIAL, 1);
- write_aux_reg(ARC_REG_IO_COH_ENABLE, 1);
+ write_aux_reg(ARC_REG_IO_COH_PARTIAL, ARC_IO_COH_PARTIAL_BIT);
+ write_aux_reg(ARC_REG_IO_COH_ENABLE, ARC_IO_COH_ENABLE_BIT);
/* Re-enable L1 dcache */
__dc_enable();
@@ -1265,7 +1279,7 @@ void __init arc_cache_init_master(void)
if (is_isa_arcv2() && l2_line_sz && !slc_enable)
arc_slc_disable();
- if (is_isa_arcv2() && ioc_enable)
+ if (is_isa_arcv2() && ioc_exists)
arc_ioc_setup();
if (is_isa_arcv2() && l2_line_sz && slc_enable) {