[PATCH v2 19/21] ppc: qemu: Create a virtual memory mapping of the platform bus

[Vladimir Oltean]

On Fri, Mar 12, 2021 at 09:36:00PM +0800, Bin Meng wrote:
> QEMU ppce500 target can dynamically instantiate an eTSEC device on
> a platform bus if "-device eTSEC" is given to QEMU. It is presented
> as a "simple-bus" in the device tree, with an additional compatible
> string "qemu,platform".
> 
> Let's create a virtual memory mapping for it in misc_init_r(), in
> preparation to adding eTSEC support.
> 
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> 
> ---
> 
> Changes in v2:
> - turn on CONFIG_SIMPLE_BUS_CORRECT_RANGE in qemu-ppce500_defconfig
> 
>  board/emulation/qemu-ppce500/Kconfig        |  6 ++++++
>  board/emulation/qemu-ppce500/qemu-ppce500.c | 18 ++++++++++++++++++
>  configs/qemu-ppce500_defconfig              |  1 +
>  3 files changed, 25 insertions(+)
> 
> diff --git a/board/emulation/qemu-ppce500/Kconfig b/board/emulation/qemu-ppce500/Kconfig
> index 4312d986d8..1c5aa18aa9 100644
> --- a/board/emulation/qemu-ppce500/Kconfig
> +++ b/board/emulation/qemu-ppce500/Kconfig
> @@ -9,4 +9,10 @@ config SYS_VENDOR
>  config SYS_CONFIG_NAME
>  	default "qemu-ppce500"
>  
> +config PLATFORM_BUS_MAP_ADDR
> +	hex
> +	default 0xf0000000
> +	help
> +	  The QEMU platform bus base mapped address in the virtual memory space.
> +
>  endif
> diff --git a/board/emulation/qemu-ppce500/qemu-ppce500.c b/board/emulation/qemu-ppce500/qemu-ppce500.c
> index daa103c564..0960dd1f97 100644
> --- a/board/emulation/qemu-ppce500/qemu-ppce500.c
> +++ b/board/emulation/qemu-ppce500/qemu-ppce500.c
> @@ -14,6 +14,8 @@
>  #include <net.h>
>  #include <pci.h>
>  #include <time.h>
> +#include <dm/simple_bus.h>
> +#include <dm/uclass-internal.h>
>  #include <asm/global_data.h>
>  #include <asm/processor.h>
>  #include <asm/mmu.h>
> @@ -148,6 +150,22 @@ int misc_init_r(void)
>  	 */
>  	disable_tlb(find_tlb_idx((void *)CONFIG_SYS_TMPVIRT, 1));
>  
> +	/*
> +	 * Detect the presence of the platform bus node, and
> +	 * create a virtual memory mapping for it.
> +	 */
> +	for (ret = uclass_find_first_device(UCLASS_SIMPLE_BUS, &dev);
> +	     dev;
> +	     ret = uclass_find_next_device(&dev)) {
> +		if (device_is_compatible(dev, "qemu,platform")) {
> +			struct simple_bus_plat *plat = dev_get_uclass_plat(dev);
> +
> +			assert(!tlb_map_range(CONFIG_PLATFORM_BUS_MAP_ADDR,
> +					      plat->target, plat->size,
> +					      TLB_MAP_IO));

A break here, maybe?
If there are multiple qemu,platform nodes, your code will attempt to
create multiple TLB mappings towards the same virtual address
CONFIG_PLATFORM_BUS_MAP_ADDR, which will not work. So better avoid that.

And maybe you can refactor this into a dedicated function, similar to
what exists for PCI.

> +		}
> +	}
> +
>  	return 0;
>  }
}

>  
> diff --git a/configs/qemu-ppce500_defconfig b/configs/qemu-ppce500_defconfig
> index 536fe7d6e1..151834b4cf 100644
> --- a/configs/qemu-ppce500_defconfig
> +++ b/configs/qemu-ppce500_defconfig
> @@ -28,6 +28,7 @@ CONFIG_OF_BOARD=y
>  CONFIG_ENV_OVERWRITE=y
>  CONFIG_SYS_RELOC_GD_ENV_ADDR=y
>  CONFIG_DM=y
> +CONFIG_SIMPLE_BUS_CORRECT_RANGE=y
>  CONFIG_BLK=y
>  CONFIG_HAVE_BLOCK_DEVICE=y
>  CONFIG_MPC8XXX_GPIO=y
> -- 
> 2.25.1
>