From: Vaibhav Bedia <vaibhav.be...@ti.com> 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.be...@ti.com> Signed-off-by: Dave Gerlach <d-gerl...@ti.com> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html