Re: [RFC PATCH-for-6.1 03/10] hw/arm/musicpal: Map flash using memory_region_add_subregion_aliased()

[Philippe Mathieu-Daudé]

On 3/26/21 1:27 AM, Philippe Mathieu-Daudé wrote:
> Instead of using a device specific feature for mapping the
> flash memory multiple times over a wider region, use the
> generic memory_region_add_subregion_aliased() helper.
> 
> There is no change in the memory layout.

- before:

  (qemu) info mtree
  00000000fe000000-00000000ffffffff (prio 0, i/o): pflash
    00000000fe000000-00000000fe7fffff (prio 0, romd): alias pflash-alias
@musicpal.flash 0000000000000000-00000000007fffff
    00000000fe800000-00000000feffffff (prio 0, romd): alias pflash-alias
@musicpal.flash 0000000000000000-00000000007fffff
    00000000ff000000-00000000ff7fffff (prio 0, romd): alias pflash-alias
@musicpal.flash 0000000000000000-00000000007fffff
    00000000ff800000-00000000ffffffff (prio 0, romd): alias pflash-alias
@musicpal.flash 0000000000000000-00000000007fffff

- after:

  00000000fe000000-00000000ffffffff (prio 0, i/o): masked musicpal.flash
[span of 8 MiB]
    00000000fe000000-00000000fe7fffff (prio 0, romd): alias
musicpal.flash [#0/4] @musicpal.flash 0000000000000000-00000000007fffff
    00000000fe800000-00000000feffffff (prio 0, romd): alias
musicpal.flash [#1/4] @musicpal.flash 0000000000000000-00000000007fffff
    00000000ff000000-00000000ff7fffff (prio 0, romd): alias
musicpal.flash [#2/4] @musicpal.flash 0000000000000000-00000000007fffff
    00000000ff800000-00000000ffffffff (prio 0, romd): alias
musicpal.flash [#3/4] @musicpal.flash 0000000000000000-00000000007fffff

Flatview is the same:

  (qemu) info mtree -f
  FlatView #0
   AS "memory", root: system
   AS "cpu-memory-0", root: system
   AS "emac-dma", root: system
   Root memory region: system
    00000000fe000000-00000000fe7fffff (prio 0, romd): musicpal.flash
    00000000fe800000-00000000feffffff (prio 0, romd): musicpal.flash
    00000000ff000000-00000000ff7fffff (prio 0, romd): musicpal.flash
    00000000ff800000-00000000ffffffff (prio 0, romd): musicpal.flash

> 
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  hw/arm/musicpal.c | 11 +++++++----
>  hw/arm/Kconfig    |  1 +
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/arm/musicpal.c b/hw/arm/musicpal.c
> index 8b58b66f263..7d1f2f3fb3f 100644
> --- a/hw/arm/musicpal.c
> +++ b/hw/arm/musicpal.c
> @@ -30,6 +30,7 @@
>  #include "hw/irq.h"
>  #include "hw/or-irq.h"
>  #include "hw/audio/wm8750.h"
> +#include "hw/misc/aliased_region.h"
>  #include "sysemu/block-backend.h"
>  #include "sysemu/runstate.h"
>  #include "sysemu/dma.h"
> @@ -1656,7 +1657,7 @@ static void musicpal_init(MachineState *machine)
>          qdev_prop_set_uint32(dev, "num-blocks", flash_size / sector_size);
>          qdev_prop_set_uint32(dev, "sector-length", sector_size);
>          qdev_prop_set_uint8(dev, "width", 2); /* 16-bit */
> -        qdev_prop_set_uint8(dev, "mappings", MP_FLASH_SIZE_MAX / flash_size);
> +        qdev_prop_set_uint8(dev, "mappings", 0);
>          qdev_prop_set_uint8(dev, "big-endian", 0);
>          qdev_prop_set_uint16(dev, "id0", 0x00bf);
>          qdev_prop_set_uint16(dev, "id1", 0x236d);
> @@ -1667,14 +1668,16 @@ static void musicpal_init(MachineState *machine)
>          qdev_prop_set_string(dev, "name", "musicpal.flash");
>          sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
>  
> -        sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0,
> -                        0x100000000ULL - MP_FLASH_SIZE_MAX);
> -
>          /*
>           * The original U-Boot accesses the flash at 0xFE000000 instead of
>           * 0xFF800000 (if there is 8 MB flash). So remap flash access if the
>           * image is smaller than 32 MB.
>           */
> +        memory_region_add_subregion_aliased(get_system_memory(),
> +                                0x100000000ULL - MP_FLASH_SIZE_MAX,
> +                                MP_FLASH_SIZE_MAX,
> +                                sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 
> 0),
> +                                flash_size);
>      }
>      sysbus_create_simple(TYPE_MV88W8618_FLASHCFG, MP_FLASHCFG_BASE, NULL);
>  
> diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
> index 8c37cf00da7..aa8553b3cd3 100644
> --- a/hw/arm/Kconfig
> +++ b/hw/arm/Kconfig
> @@ -101,6 +101,7 @@ config MUSICPAL
>      select MARVELL_88W8618
>      select PTIMER
>      select PFLASH_CFI02
> +    select ALIASED_REGION
>      select SERIAL
>      select WM8750
>  
>