Re: [PATCH 07/11] armv7m: Make bitband device take the address space to access

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> Instead of the bitband device doing a cpu_physical_memory_read/write,
> make it take a MemoryRegion which specifies where it should be
> accessing, and use address_space_read/write to access the
> corresponding AddressSpace.
>
> Since this entails pretty much a rewrite, convert away from
> old_mmio in the process.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  include/hw/arm/armv7m.h |   2 +
>  hw/arm/armv7m.c         | 166 +++++++++++++++++++++++-------------------------
>  2 files changed, 81 insertions(+), 87 deletions(-)
>
> diff --git a/include/hw/arm/armv7m.h b/include/hw/arm/armv7m.h
> index 3333c91..a9b3f2a 100644
> --- a/include/hw/arm/armv7m.h
> +++ b/include/hw/arm/armv7m.h
> @@ -21,8 +21,10 @@ typedef struct {
>      SysBusDevice parent_obj;
>      /*< public >*/
>
> +    AddressSpace *source_as;
>      MemoryRegion iomem;
>      uint32_t base;
> +    MemoryRegion *source_memory;
>  } BitBandState;
>
>  #define TYPE_ARMV7M "armv7m"
> diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
> index fb21f74..4481106 100644
> --- a/hw/arm/armv7m.c
> +++ b/hw/arm/armv7m.c
> @@ -23,103 +23,73 @@
>  /* Bitbanded IO.  Each word corresponds to a single bit.  */
>
>  /* Get the byte address of the real memory for a bitband access.  */
> -static inline uint32_t bitband_addr(void * opaque, uint32_t addr)
> +static inline hwaddr bitband_addr(BitBandState *s, hwaddr offset)
>  {
> -    uint32_t res;
> -
> -    res = *(uint32_t *)opaque;
> -    res |= (addr & 0x1ffffff) >> 5;
> -    return res;
> -
> -}
> -
> -static uint32_t bitband_readb(void *opaque, hwaddr offset)
> -{
> -    uint8_t v;
> -    cpu_physical_memory_read(bitband_addr(opaque, offset), &v, 1);
> -    return (v & (1 << ((offset >> 2) & 7))) != 0;
> -}
> -
> -static void bitband_writeb(void *opaque, hwaddr offset,
> -                           uint32_t value)
> -{
> -    uint32_t addr;
> -    uint8_t mask;
> -    uint8_t v;
> -    addr = bitband_addr(opaque, offset);
> -    mask = (1 << ((offset >> 2) & 7));
> -    cpu_physical_memory_read(addr, &v, 1);
> -    if (value & 1)
> -        v |= mask;
> -    else
> -        v &= ~mask;
> -    cpu_physical_memory_write(addr, &v, 1);
> -}
> -
> -static uint32_t bitband_readw(void *opaque, hwaddr offset)
> -{
> -    uint32_t addr;
> -    uint16_t mask;
> -    uint16_t v;
> -    addr = bitband_addr(opaque, offset) & ~1;
> -    mask = (1 << ((offset >> 2) & 15));
> -    mask = tswap16(mask);
> -    cpu_physical_memory_read(addr, &v, 2);
> -    return (v & mask) != 0;
> -}
> -
> -static void bitband_writew(void *opaque, hwaddr offset,
> -                           uint32_t value)
> -{
> -    uint32_t addr;
> -    uint16_t mask;
> -    uint16_t v;
> -    addr = bitband_addr(opaque, offset) & ~1;
> -    mask = (1 << ((offset >> 2) & 15));
> -    mask = tswap16(mask);
> -    cpu_physical_memory_read(addr, &v, 2);
> -    if (value & 1)
> -        v |= mask;
> -    else
> -        v &= ~mask;
> -    cpu_physical_memory_write(addr, &v, 2);
> +    return s->base | (offset & 0x1ffffff) >> 5;
>  }
>
> -static uint32_t bitband_readl(void *opaque, hwaddr offset)
> +static MemTxResult bitband_read(void *opaque, hwaddr offset,
> +                                uint64_t *data, unsigned size, MemTxAttrs attrs)
>  {
> -    uint32_t addr;
> -    uint32_t mask;
> -    uint32_t v;
> -    addr = bitband_addr(opaque, offset) & ~3;
> -    mask = (1 << ((offset >> 2) & 31));
> -    mask = tswap32(mask);
> -    cpu_physical_memory_read(addr, &v, 4);
> -    return (v & mask) != 0;
> +    BitBandState *s = opaque;
> +    uint8_t buf[4];
> +    MemTxResult res;
> +    int bitpos, bit;
> +    hwaddr addr;
> +
> +    assert(size <= 4);
> +
> +    /* Find address in underlying memory and round down to multiple of size */
> +    addr = bitband_addr(s, offset) & (-size);
> +    res = address_space_read(s->source_as, addr, attrs, buf, size);
> +    if (res) {
> +        return res;
> +    }
> +    /* Bit position in the N bytes read... */
> +    bitpos = (offset >> 2) & ((size * 8) - 1);
> +    /* ...converted to byte in buffer and bit in byte */
> +    bit = (buf[bitpos >> 3] >> (bitpos & 7)) & 1;
> +    *data = bit;
> +    return MEMTX_OK;
>  }
>
> -static void bitband_writel(void *opaque, hwaddr offset,
> -                           uint32_t value)
> +static MemTxResult bitband_write(void *opaque, hwaddr offset, uint64_t value,
> +                                 unsigned size, MemTxAttrs attrs)
>  {
> -    uint32_t addr;
> -    uint32_t mask;
> -    uint32_t v;
> -    addr = bitband_addr(opaque, offset) & ~3;
> -    mask = (1 << ((offset >> 2) & 31));
> -    mask = tswap32(mask);
> -    cpu_physical_memory_read(addr, &v, 4);
> -    if (value & 1)
> -        v |= mask;
> -    else
> -        v &= ~mask;
> -    cpu_physical_memory_write(addr, &v, 4);
> +    BitBandState *s = opaque;
> +    uint8_t buf[4];
> +    MemTxResult res;
> +    int bitpos, bit;
> +    hwaddr addr;
> +
> +    assert(size <= 4);
> +
> +    /* Find address in underlying memory and round down to multiple of size */
> +    addr = bitband_addr(s, offset) & (-size);
> +    res = address_space_read(s->source_as, addr, attrs, buf, size);
> +    if (res) {
> +        return res;
> +    }
> +    /* Bit position in the N bytes read... */
> +    bitpos = (offset >> 2) & ((size * 8) - 1);
> +    /* ...converted to byte in buffer and bit in byte */
> +    bit = 1 << (bitpos & 7);
> +    if (value & 1) {
> +        buf[bitpos >> 3] |= bit;
> +    } else {
> +        buf[bitpos >> 3] &= ~bit;
> +    }
> +    return address_space_write(s->source_as, addr, attrs, buf, size);
>  }
>
>  static const MemoryRegionOps bitband_ops = {
> -    .old_mmio = {
> -        .read = { bitband_readb, bitband_readw, bitband_readl, },
> -        .write = { bitband_writeb, bitband_writew, bitband_writel, },
> -    },
> +    .read_with_attrs = bitband_read,
> +    .write_with_attrs = bitband_write,
>      .endianness = DEVICE_NATIVE_ENDIAN,
> +    .impl.min_access_size = 1,
> +    .impl.max_access_size = 4,
> +    .valid.min_access_size = 1,
> +    .valid.max_access_size = 4,
>  };
>
>  static void bitband_init(Object *obj)
> @@ -127,11 +97,30 @@ static void bitband_init(Object *obj)
>      BitBandState *s = BITBAND(obj);
>      SysBusDevice *dev = SYS_BUS_DEVICE(obj);
>
> -    memory_region_init_io(&s->iomem, obj, &bitband_ops, &s->base,
> +    object_property_add_link(obj, "source-memory",
> +                             TYPE_MEMORY_REGION,
> +                             (Object **)&s->source_memory,
> +                             qdev_prop_allow_set_link_before_realize,
> +                             OBJ_PROP_LINK_UNREF_ON_RELEASE,
> +                             &error_abort);
> +    memory_region_init_io(&s->iomem, obj, &bitband_ops, s,
>                            "bitband", 0x02000000);
>      sysbus_init_mmio(dev, &s->iomem);
>  }
>
> +static void bitband_realize(DeviceState *dev, Error **errp)
> +{
> +    BitBandState *s = BITBAND(dev);
> +
> +    if (!s->source_memory) {
> +        error_setg(errp, "source-memory property not set");
> +        return;
> +    }
> +
> +    s->source_as = address_space_init_shareable(s->source_memory,
> +                                                "bitband-source");
> +}
> +
>  /* Board init.  */
>
>  static const hwaddr bitband_input_addr[ARMV7M_NUM_BITBANDS] = {
> @@ -251,6 +240,8 @@ static void armv7m_realize(DeviceState *dev, Error **errp)
>              error_propagate(errp, err);
>              return;
>          }
> +        object_property_set_link(obj, OBJECT(s->board_memory),
> +                                 "source-memory", &error_abort);
>          object_property_set_bool(obj, true, "realized", &err);
>          if (err != NULL) {
>              error_propagate(errp, err);
> @@ -366,6 +357,7 @@ static void bitband_class_init(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
>
> +    dc->realize = bitband_realize;
>      dc->props = bitband_properties;
>  }


--
Alex Bennée