From: Vaibhav Bedia <vaibhav.bedia@xxxxxx>
SDRAM controller on AM33XX requires that a modification of certain
bit-fields in PWR_MGMT_CTRL register (ref. section 7.3.5.13 in
AM335x-Rev H) is followed by a dummy read access to SDRAM. This
scenario arises when entering a low power state like DeepSleep.
To ensure that the read is not from a cached region we reserve
some memory during bootup using the arm_memblock_steal() API. The
original call to omap_reserve is removed as it is not used in any
way on am335x.
A subsequent patch will pass along the location of the reserved
memory location to the AM335x suspend handler which modifies the
PWR_MGMT_CTRL register in the EMIF.
Signed-off-by: Vaibhav Bedia <vaibhav.bedia@xxxxxx>
Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
---
v3->v4:
Left as is because of use in sram code when EMIF is off to avoid
copying additional code. Also uses hardcoded virtual address now
to avoid problems with himem
arch/arm/mach-omap2/board-generic.c | 2 +-
arch/arm/mach-omap2/common.c | 32 ++++++++++++++++++++++++++++++++
arch/arm/mach-omap2/common.h | 4 ++++
arch/arm/mach-omap2/io.c | 1 +
4 files changed, 38 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
index 9480997..d2c435e 100644
--- a/arch/arm/mach-omap2/board-generic.c
+++ b/arch/arm/mach-omap2/board-generic.c
@@ -163,7 +163,7 @@ static const char *am33xx_boards_compat[] __initconst = {
};
DT_MACHINE_START(AM33XX_DT, "Generic AM33XX (Flattened Device Tree)")
- .reserve = omap_reserve,
+ .reserve = am33xx_reserve,
.map_io = am33xx_map_io,
.init_early = am33xx_init_early,
.init_irq = omap_intc_of_init,
diff --git a/arch/arm/mach-omap2/common.c b/arch/arm/mach-omap2/common.c
index 2dabb9e..df6394e 100644
--- a/arch/arm/mach-omap2/common.c
+++ b/arch/arm/mach-omap2/common.c
@@ -15,10 +15,14 @@
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_data/dsp-omap.h>
+#include <asm/memblock.h>
+#include <asm/mach/map.h>
#include "common.h"
#include "omap-secure.h"
+#define AM33XX_DRAM_SYNC_VA 0xfe600000
+
/*
* Stub function for OMAP2 so that common files
* continue to build when custom builds are used
@@ -34,3 +38,31 @@ void __init omap_reserve(void)
omap_secure_ram_reserve_memblock();
omap_barrier_reserve_memblock();
}
+
+static phys_addr_t am33xx_paddr;
+static u32 am33xx_size;
+
+/* Steal one page physical memory for uncached read DeepSleep */
+void __init am33xx_reserve(void)
+{
+ am33xx_size = ALIGN(PAGE_SIZE, SZ_1M);
+ am33xx_paddr = arm_memblock_steal(am33xx_size, SZ_1M);
+
+ omap_reserve();
+}
+
+void __iomem *am33xx_dram_sync;
+
+void __init am33xx_dram_sync_init(void)
+{
+ struct map_desc dram_io_desc[1];
+
+ dram_io_desc[0].virtual = AM33XX_DRAM_SYNC_VA;
+ dram_io_desc[0].pfn = __phys_to_pfn(am33xx_paddr);
+ dram_io_desc[0].length = am33xx_size;
+ dram_io_desc[0].type = MT_MEMORY_RW_SO;
+
+ iotable_init(dram_io_desc, ARRAY_SIZE(dram_io_desc));
+
+ am33xx_dram_sync = (void __iomem *) dram_io_desc[0].virtual;
+}
diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h
index b2d252b..1536338 100644
--- a/arch/arm/mach-omap2/common.h
+++ b/arch/arm/mach-omap2/common.h
@@ -316,6 +316,10 @@ extern void omap_sdrc_init(struct omap_sdrc_params *sdrc_cs0,
struct omap2_hsmmc_info;
extern void omap_reserve(void);
+extern void am33xx_reserve(void);
+extern void am33xx_dram_sync_init(void);
+extern void __iomem *am33xx_dram_sync;
+
struct omap_hwmod;
extern int omap_dss_reset(struct omap_hwmod *);
diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
index 8f55945..4d4d150 100644
--- a/arch/arm/mach-omap2/io.c
+++ b/arch/arm/mach-omap2/io.c
@@ -313,6 +313,7 @@ void __init ti81xx_map_io(void)
void __init am33xx_map_io(void)
{
iotable_init(omapam33xx_io_desc, ARRAY_SIZE(omapam33xx_io_desc));
+ am33xx_dram_sync_init();
}
#endif
--
1.9.0
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