Re: [Qemu-devel] [PATCH v5 03/15] register: Add Memory API glue

[Alistair Francis]

On Tue, Mar 22, 2016 at 9:56 AM, Alex Bennée <address@hidden> wrote:
>
> Alistair Francis <address@hidden> writes:
>
>> Add memory io handlers that glue the register API to the memory API.
>> Just translation functions at this stage. Although it does allow for
>> devices to be created without all-in-one mmio r/w handlers.
>>
>> This patch also adds the RegisterInfoArray struct, which allows all of
>> the individual RegisterInfo structs to be grouped into a single memory
>> region.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>> Signed-off-by: Alistair Francis <address@hidden>
>> ---
>> V5:
>>  - Convert to using only one memory region
>>
>>  hw/core/register.c    | 70 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  include/hw/register.h | 51 +++++++++++++++++++++++++++++++++++++
>>  2 files changed, 121 insertions(+)
>>
>> diff --git a/hw/core/register.c b/hw/core/register.c
>> index 1656f71..e1cd0c4 100644
>> --- a/hw/core/register.c
>> +++ b/hw/core/register.c
>> @@ -146,3 +146,73 @@ void register_reset(RegisterInfo *reg)
>>
>>      register_write_val(reg, reg->access->reset);
>>  }
>> +
>> +static inline void register_write_memory(void *opaque, hwaddr addr,
>> +                                         uint64_t value, unsigned size, 
>> bool be)
>> +{
>> +    RegisterInfoArray *reg_array = opaque;
>> +    RegisterInfo *reg = NULL;
>> +    uint64_t we = ~0;
>> +    int i, shift = 0;
>> +
>> +    for (i = 0; i < reg_array->num_elements; i++) {
>> +        if (reg_array->r[i]->access->decode.addr == addr) {
>> +            reg = reg_array->r[i];
>> +            break;
>> +        }
>> +    }
>> +    assert(reg);
>> +
>> +    /* Generate appropriate write enable mask and shift values */
>> +    if (reg->data_size < size) {
>> +        we = MAKE_64BIT_MASK(0, reg->data_size * 8);
>> +        shift = 8 * (be ? reg->data_size - size : 0);
>> +    } else if (reg->data_size >= size) {
>> +        we = MAKE_64BIT_MASK(0, size * 8);
>> +    }
>> +
>> +    register_write(reg, value << shift, we << shift);
>> +}
>> +
>> +void register_write_memory_be(void *opaque, hwaddr addr, uint64_t value,
>> +                              unsigned size)
>> +{
>> +    register_write_memory(opaque, addr, value, size, true);
>> +}
>> +
>> +
>> +void register_write_memory_le(void *opaque, hwaddr addr, uint64_t value,
>> +                              unsigned size)
>> +{
>> +    register_write_memory(opaque, addr, value, size, false);
>> +}
>> +
>> +static inline uint64_t register_read_memory(void *opaque, hwaddr addr,
>> +                                            unsigned size, bool be)
>> +{
>> +    RegisterInfoArray *reg_array = opaque;
>> +    RegisterInfo *reg = NULL;
>> +    int i, shift;
>> +
>> +    for (i = 0; i < reg_array->num_elements; i++) {
>> +        if (reg_array->r[i]->access->decode.addr == addr) {
>> +            reg = reg_array->r[i];
>> +            break;
>> +        }
>> +    }
>> +    assert(reg);
>> +
>> +    shift = 8 * (be ? reg->data_size - size : 0);
>> +
>> +    return (register_read(reg) >> shift) & MAKE_64BIT_MASK(0, size * 8);
>> +}
>> +
>> +uint64_t register_read_memory_be(void *opaque, hwaddr addr, unsigned size)
>> +{
>> +    return register_read_memory(opaque, addr, size, true);
>> +}
>> +
>> +uint64_t register_read_memory_le(void *opaque, hwaddr addr, unsigned size)
>> +{
>> +    return register_read_memory(opaque, addr, size, false);
>> +}
>> diff --git a/include/hw/register.h b/include/hw/register.h
>> index baa08f5..726a914 100644
>> --- a/include/hw/register.h
>> +++ b/include/hw/register.h
>> @@ -15,6 +15,7 @@
>>
>>  typedef struct RegisterInfo RegisterInfo;
>>  typedef struct RegisterAccessInfo RegisterAccessInfo;
>> +typedef struct RegisterInfoArray RegisterInfoArray;
>>
>>  /**
>>   * Access description for a register that is part of guest accessible device
>> @@ -51,6 +52,10 @@ struct RegisterAccessInfo {
>>      void (*post_write)(RegisterInfo *reg, uint64_t val);
>>
>>      uint64_t (*post_read)(RegisterInfo *reg, uint64_t val);
>> +
>> +    struct {
>> +        hwaddr addr;
>> +    } decode;
>>  };
>>
>>  /**
>> @@ -82,6 +87,26 @@ struct RegisterInfo {
>>  };
>>
>>  /**
>> + * This structure is used to group all of the individual registers which are
>> + * modeled using the RegisterInfo strucutre.
>> + *
>> + * @r is an aray containing of all the relevent RegisterInfo structures.
>> + *
>> + * @num_elements is the number of elements in the array r
>> + *
>> + * @mem: optional Memory region for the register
>> + */
>> +
>> +struct RegisterInfoArray {
>> +    /* <private> */
>> +    MemoryRegion mem;
>
> I never see this used. I thought with the other changes the memory

It isn't used here, it is used later on in the series when the
register_init_block32() function is added.

I can move it back to the patch if you wish.

> region enclosed the group of registers. Wouldn't a private mem violate that?

Yes, you are right. I'll remove the private comment.

>
>> +
>> +    /* <public> */
>> +    int num_elements;
>> +    RegisterInfo **r;
>> +};
>
> Without the extra bits why re-invent GArray?

What do you mean?

Thanks,

Alistair

>
>> +
>> +/**
>>   * write a value to a register, subject to its restrictions
>>   * @reg: register to write to
>>   * @val: value to write
>> @@ -105,4 +130,30 @@ uint64_t register_read(RegisterInfo *reg);
>>
>>  void register_reset(RegisterInfo *reg);
>>
>> +/**
>> + * Memory API MMIO write handler that will write to a Register API register.
>> + *  _be for big endian variant and _le for little endian.
>> + * @opaque: RegisterInfo to write to
>> + * @addr: Address to write
>> + * @value: Value to write
>> + * @size: Number of bytes to write
>> + */
>> +
>> +void register_write_memory_be(void *opaque, hwaddr addr, uint64_t value,
>> +                              unsigned size);
>> +void register_write_memory_le(void *opaque, hwaddr addr, uint64_t value,
>> +                              unsigned size);
>> +
>> +/**
>> + * Memory API MMIO read handler that will read from a Register API register.
>> + *  _be for big endian variant and _le for little endian.
>> + * @opaque: RegisterInfo to read from
>> + * @addr: Address to read
>> + * @size: Number of bytes to read
>> + * returns: Value read from register
>> + */
>> +
>> +uint64_t register_read_memory_be(void *opaque, hwaddr addr, unsigned size);
>> +uint64_t register_read_memory_le(void *opaque, hwaddr addr, unsigned size);
>> +
>>  #endif
>
>
> --
> Alex Bennée
>