On Tue, Aug 6, 2013 at 10:49 AM, Dave Gerlach <d-gerlach@xxxxxx> wrote:
> 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.
>
> 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>
Reviewed-by: Russ Dill <russ.dill@xxxxxx>
> ---
> arch/arm/mach-omap2/board-generic.c | 2 +-
> arch/arm/mach-omap2/common.c | 28 ++++++++++++++++++++++++++++
> arch/arm/mach-omap2/common.h | 4 ++++
> arch/arm/mach-omap2/io.c | 1 +
> 4 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
> index be5d005..aed750c 100644
> --- a/arch/arm/mach-omap2/board-generic.c
> +++ b/arch/arm/mach-omap2/board-generic.c
> @@ -156,7 +156,7 @@ static const char *am33xx_boards_compat[] __initdata = {
> };
>
> 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..756586f 100644
> --- a/arch/arm/mach-omap2/common.c
> +++ b/arch/arm/mach-omap2/common.c
> @@ -15,6 +15,8 @@
> #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"
> @@ -34,3 +36,29 @@ 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);
> +}
> +
> +void __iomem *am33xx_dram_sync;
> +
> +void __init am33xx_dram_sync_init(void)
> +{
> + struct map_desc dram_io_desc[1];
> +
> + dram_io_desc[0].virtual = __phys_to_virt(am33xx_paddr);
> + dram_io_desc[0].pfn = __phys_to_pfn(am33xx_paddr);
> + dram_io_desc[0].length = am33xx_size;
> + dram_io_desc[0].type = MT_MEMORY_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 dfcc182..6b8ef74 100644
> --- a/arch/arm/mach-omap2/common.h
> +++ b/arch/arm/mach-omap2/common.h
> @@ -294,6 +294,10 @@ struct omap2_hsmmc_info;
> extern int omap4_twl6030_hsmmc_init(struct omap2_hsmmc_info *controllers);
> 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 4a3f06f..3ad7543 100644
> --- a/arch/arm/mach-omap2/io.c
> +++ b/arch/arm/mach-omap2/io.c
> @@ -322,6 +322,7 @@ 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
>
> --
> 1.7.9.5
>
> --
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