On 7 August 2018 at 08:57, Joel Stanley <j...@jms.id.au> wrote:
> From: Cédric Le Goater <c...@kaod.org>
>
> This will be used to construct a memory region beyond the RAM region
> to let firmwares scan the address space with load/store to guess how
> much RAM the SoC has.
>
> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> Signed-off-by: Joel Stanley <j...@jms.id.au>
> ---
> hw/arm/aspeed.c | 31 +++++++++++++++++++++++++++++++
> hw/arm/aspeed_soc.c | 2 ++
> hw/misc/aspeed_sdmc.c | 3 +++
> include/hw/misc/aspeed_sdmc.h | 1 +
> 4 files changed, 37 insertions(+)
>
> diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
> index bb9d33848d3f..e078269266bc 100644
> --- a/hw/arm/aspeed.c
> +++ b/hw/arm/aspeed.c
> @@ -31,6 +31,7 @@ static struct arm_boot_info aspeed_board_binfo = {
> typedef struct AspeedBoardState {
> AspeedSoCState soc;
> MemoryRegion ram;
> + MemoryRegion max_ram;
> } AspeedBoardState;
>
> typedef struct AspeedBoardConfig {
> @@ -127,6 +128,27 @@ static const AspeedBoardConfig aspeed_boards[] = {
> },
> };
>
> +/*
> + * The max ram region is for firmwares that scan the address space
> + * with load/store to guess how much RAM the SoC has.
> + */
> +static uint64_t max_ram_read(void *opaque, hwaddr offset, unsigned size)
> +{
> + return 0;
> +}
> +
> +static void max_ram_write(void *opaque, hwaddr offset, uint64_t value,
> + unsigned size)
> +{
> + /* Disacard writes */
> +}
> +
> +static const MemoryRegionOps max_ram_ops = {
> + .read = max_ram_read,
> + .write = max_ram_write,
> + .endianness = DEVICE_NATIVE_ENDIAN,
> +};
> +
> #define FIRMWARE_ADDR 0x0
>
> static void write_boot_rom(DriveInfo *dinfo, hwaddr addr, size_t rom_size,
> @@ -187,6 +209,7 @@ static void aspeed_board_init(MachineState *machine,
> AspeedBoardState *bmc;
> AspeedSoCClass *sc;
> DriveInfo *drive0 = drive_get(IF_MTD, 0, 0);
> + ram_addr_t max_ram_size;
>
> bmc = g_new0(AspeedBoardState, 1);
> object_initialize(&bmc->soc, (sizeof(bmc->soc)), cfg->soc_name);
> @@ -226,6 +249,14 @@ static void aspeed_board_init(MachineState *machine,
> object_property_add_const_link(OBJECT(&bmc->soc), "ram",
> OBJECT(&bmc->ram),
> &error_abort);
>
> + max_ram_size = object_property_get_uint(OBJECT(&bmc->soc),
> "max-ram-size",
> + &error_abort);
> + memory_region_init_io(&bmc->max_ram, NULL, &max_ram_ops, NULL,
> + "max_ram", max_ram_size - ram_size);
> + memory_region_add_subregion(get_system_memory(),
> + sc->info->sdram_base + ram_size,
> + &bmc->max_ram);
I'm surprised that you need the IO ops, ie that it doesn't work
just to define an empty container region with memory_region_init().
thanks
-- PMM
