Re: [PATCH 07/11] hw/ppc/e500: Implement pflash handling

[Bin Meng]

On Thu, Sep 15, 2022 at 11:36 PM Bernhard Beschow <shentey@gmail.com> wrote:
>
> Allows e500 boards to have their root file system reside on flash using
> only builtin devices.
>
> Note that the flash memory area is only created when a -pflash argument is
> given, and that the size is determined by the given file. The idea is to
> put users into control.
>
> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
> ---
>  docs/system/ppc/ppce500.rst | 12 +++++++++
>  hw/ppc/Kconfig              |  1 +
>  hw/ppc/e500.c               | 54 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 67 insertions(+)
>
> diff --git a/docs/system/ppc/ppce500.rst b/docs/system/ppc/ppce500.rst
> index ba6bcb7314..c3f55c6f3d 100644
> --- a/docs/system/ppc/ppce500.rst
> +++ b/docs/system/ppc/ppce500.rst
> @@ -119,6 +119,18 @@ To boot the 32-bit Linux kernel:
>        -initrd /path/to/rootfs.cpio \
>        -append "root=/dev/ram"
>
> +Rather than using a root file system on ram disk, it is possible to have it 
> on
> +emulated flash. Given an ext2 image whose size must be a power of two, it can
> +be used as follows:
> +
> +.. code-block:: bash
> +
> +  $ qemu-system-ppc64 -M ppce500 -cpu e500mc -smp 4 -m 2G \

qemu-system-ppc{64|32}

> +      -display none -serial stdio \
> +      -kernel vmlinux \
> +      -drive if=pflash,file=/path/to/rootfs.ext2,format=raw \
> +      -append "rootwait root=/dev/mtdblock0"
> +
>  Running U-Boot
>  --------------
>
> diff --git a/hw/ppc/Kconfig b/hw/ppc/Kconfig
> index 791fe78a50..769a1ead1c 100644
> --- a/hw/ppc/Kconfig
> +++ b/hw/ppc/Kconfig
> @@ -126,6 +126,7 @@ config E500
>      select ETSEC
>      select GPIO_MPC8XXX
>      select OPENPIC
> +    select PFLASH_CFI01
>      select PLATFORM_BUS
>      select PPCE500_PCI
>      select SERIAL
> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
> index 864b6f3d92..7843a4e04b 100644
> --- a/hw/ppc/e500.c
> +++ b/hw/ppc/e500.c
> @@ -23,8 +23,10 @@
>  #include "e500-ccsr.h"
>  #include "net/net.h"
>  #include "qemu/config-file.h"
> +#include "hw/block/flash.h"
>  #include "hw/char/serial.h"
>  #include "hw/pci/pci.h"
> +#include "sysemu/block-backend-io.h"
>  #include "sysemu/sysemu.h"
>  #include "sysemu/kvm.h"
>  #include "sysemu/reset.h"
> @@ -267,6 +269,34 @@ static void sysbus_device_create_devtree(SysBusDevice 
> *sbdev, void *opaque)
>      }
>  }
>
> +static void create_devtree_flash(SysBusDevice *sbdev,
> +                                 PlatformDevtreeData *data)
> +{
> +    char *name;

Use g_autofree

> +    uint64_t num_blocks = object_property_get_uint(OBJECT(sbdev),
> +                                                   "num-blocks",
> +                                                   &error_fatal);
> +    uint64_t sector_length = object_property_get_uint(OBJECT(sbdev),
> +                                                      "sector-length",
> +                                                      &error_fatal);
> +    uint64_t bank_width = object_property_get_uint(OBJECT(sbdev),
> +                                                   "width",
> +                                                   &error_fatal);
> +    hwaddr flashbase = 0;
> +    hwaddr flashsize = num_blocks * sector_length;
> +    void *fdt = data->fdt;
> +
> +    name = g_strdup_printf("%s/nor@%" PRIx64, data->node, flashbase);
> +    qemu_fdt_add_subnode(fdt, name);
> +    qemu_fdt_setprop_cell(fdt, name, "#address-cells", 1);
> +    qemu_fdt_setprop_cell(fdt, name, "#size-cells", 1);

#address-cells and #size-cells are not needed.

> +    qemu_fdt_setprop_string(fdt, name, "compatible", "cfi-flash");
> +    qemu_fdt_setprop_sized_cells(fdt, name, "reg",
> +                                 1, flashbase, 1, flashsize);
> +    qemu_fdt_setprop_cell(fdt, name, "bank-width", bank_width);
> +    g_free(name);
> +}
> +
>  static void platform_bus_create_devtree(PPCE500MachineState *pms,
>                                          void *fdt, const char *mpic)
>  {
> @@ -276,6 +306,8 @@ static void 
> platform_bus_create_devtree(PPCE500MachineState *pms,
>      uint64_t addr = pmc->platform_bus_base;
>      uint64_t size = pmc->platform_bus_size;
>      int irq_start = pmc->platform_bus_first_irq;
> +    SysBusDevice *sbdev;
> +    bool ambiguous;
>
>      /* Create a /platform node that we can put all devices into */
>
> @@ -302,6 +334,13 @@ static void 
> platform_bus_create_devtree(PPCE500MachineState *pms,
>      /* Loop through all dynamic sysbus devices and create nodes for them */
>      foreach_dynamic_sysbus_device(sysbus_device_create_devtree, &data);
>
> +    sbdev = SYS_BUS_DEVICE(object_resolve_path_type("", TYPE_PFLASH_CFI01,
> +                                                    &ambiguous));

Can this be moved into sysbus_device_create_devtree(), and use the
same logic as the eTSEC device?

> +    if (sbdev) {
> +        assert(!ambiguous);
> +        create_devtree_flash(sbdev, &data);
> +    }
> +
>      g_free(node);
>  }
>
> @@ -856,6 +895,7 @@ void ppce500_init(MachineState *machine)
>      unsigned int pci_irq_nrs[PCI_NUM_PINS] = {1, 2, 3, 4};
>      IrqLines *irqs;
>      DeviceState *dev, *mpicdev;
> +    DriveInfo *dinfo;
>      CPUPPCState *firstenv = NULL;
>      MemoryRegion *ccsr_addr_space;
>      SysBusDevice *s;
> @@ -1024,6 +1064,20 @@ void ppce500_init(MachineState *machine)
>                                  pmc->platform_bus_base,
>                                  sysbus_mmio_get_region(s, 0));
>
> +    dinfo = drive_get(IF_PFLASH, 0, 0);
> +    if (dinfo) {
> +        BlockBackend *blk = blk_by_legacy_dinfo(dinfo);
> +        BlockDriverState *bs = blk_bs(blk);
> +        uint64_t size = bdrv_getlength(bs);
> +        if (ctpop64(size) != 1) {
> +            error_report("Size of pflash file must be a power of two.");
> +            exit(1);
> +        }

I think we should also check whether the flash size plus the eTSEC
size exceeds the platform bus mmio window size otherwise it won't work
for both devices present, no?

> +        pflash_cfi01_register(pmc->platform_bus_base, "e500.flash",
> +                              size, blk,
> +                              64 * KiB, 2, 0x89, 0x18, 0x0000, 0x0, 1);
> +    }
> +
>      /*
>       * Smart firmware defaults ahead!
>       *

Regards,
Bin