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

[Bernhard Beschow <shentey@gmail.com>]

Am 16. September 2022 15:00:06 UTC schrieb Bin Meng <bmeng.cn@gmail.com>:
>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}

Will fix.

>> +      -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

Yes, good idea.

>> +    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.

Will remove.

>> +    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?

I've tried that, but the logic for eTSEC seems to get triggered for user-created devices only. Since TYPE_PFLASH_CFI01 isn't user-created we're not triggered I guess.

I think that the eTSEC handling could be moved into sysbus-fdt.c but I'm not sure whether this is allowed due to poisoning.

>> +    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?

I could check that the flash fits inside the eLBC memory window.

For user-created devices such as eTSEC, however, I'd like to rely on other parts of QEMU to check this. First, I don't know how to get access to all relevant devices and their memory windows, and second, catching all possible (future) cases here seems a bit ad-hoc and fragile to me.

Best regards,
Bernhard
>
>> +        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