Re: [Qemu-devel] [PATCH] pci: add accessors to get/set registers by mask

[Isaku Yamahata]

sounds good idea and the patch Looks good.

On Tue, Feb 21, 2012 at 03:41:30PM +0200, Michael S. Tsirkin wrote:
> pci_regs.h specifies many registers by mask +
> shifted register values.
> There's always some duplication when using such:
> for example to override device type, we would need:
> 
> pci_word_test_and_clear_mask(cap + PCI_EXP_FLAGS,
>      PCI_EXP_FLAGS_TYPE);
> pci_word_test_and_set_mask(cap + PCI_EXP_FLAGS,
>     PCI_EXP_TYPE_ENDPOINT << (ffs(PCI_EXP_FLAGS_TYPE) - 1));
> 
> Getting such registers also uses some duplication:
> 
> word = pci_get_word(cap + PCI_EXP_FLAGS) & PCI_EXP_FLAGS_TYPE;
> if ((word >> ffs((PCI_EXP_FLAGS_TYPE) - 1)) == PCI_EXP_TYPE_ENDPOINT)
> 
> Add API to access such registers in one line:
> pci_set_word_by_mask(cap + PCI_EXP_FLAGS, PCI_EXP_FLAGS_TYPE,
>                    PCI_EXP_TYPE_ENDPOINT)
> 
> and
> word = pci_get_word_by_mask(cap + PCI_EXP_FLAGS, PCI_EXP_FLAGS_TYPE)
> if (word == PCI_EXP_TYPE_ENDPOINT)
> 
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  hw/pci.h |   61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 61 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/pci.h b/hw/pci.h
> index 448c44e..1103838 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -469,6 +469,67 @@ pci_quad_test_and_set_mask(uint8_t *config, uint64_t 
> mask)
>      return val & mask;
>  }
>  
> +/* Access a register specified by a mask */
> +static inline void
> +pci_set_byte_by_mask(uint8_t *config, uint8_t mask, uint8_t reg)
> +{
> +    uint8_t val = pci_get_byte(config);
> +    uint8_t rval = reg << (ffs(mask) - 1);
> +    pci_set_byte(config, (~mask & val) | (mask & rval));
> +}
> +
> +static inline uint8_t
> +pci_get_byte_by_mask(uint8_t *config, uint8_t mask)
> +{
> +    uint8_t val = pci_get_byte(config);
> +    return (val & mask) >> (ffs(mask) - 1);
> +}
> +
> +static inline void
> +pci_set_word_by_mask(uint8_t *config, uint16_t mask, uint16_t reg)
> +{
> +    uint16_t val = pci_get_word(config);
> +    uint16_t rval = reg << (ffs(mask) - 1);
> +    pci_set_word(config, (~mask & val) | (mask & rval));
> +}
> +
> +static inline uint16_t
> +pci_get_word_by_mask(uint8_t *config, uint16_t mask)
> +{
> +    uint16_t val = pci_get_word(config);
> +    return (val & mask) >> (ffs(mask) - 1);
> +}
> +
> +static inline void
> +pci_set_long_by_mask(uint8_t *config, uint32_t mask, uint32_t reg)
> +{
> +    uint32_t val = pci_get_long(config);
> +    uint32_t rval = reg << (ffs(mask) - 1);
> +    pci_set_long(config, (~mask & val) | (mask & rval));
> +}
> +
> +static inline uint32_t
> +pci_get_long_by_mask(uint8_t *config, uint32_t mask)
> +{
> +    uint32_t val = pci_get_long(config);
> +    return (val & mask) >> (ffs(mask) - 1);
> +}
> +
> +static inline void
> +pci_set_quad_by_mask(uint8_t *config, uint64_t mask, uint64_t reg)
> +{
> +    uint64_t val = pci_get_quad(config);
> +    uint64_t rval = reg << (ffs(mask) - 1);
> +    pci_set_quad(config, (~mask & val) | (mask & rval));
> +}
> +
> +static inline uint64_t
> +pci_get_quad_by_mask(uint8_t *config, uint64_t mask)
> +{
> +    uint64_t val = pci_get_quad(config);
> +    return (val & mask) >> (ffs(mask) - 1);
> +}
> +
>  PCIDevice *pci_create_multifunction(PCIBus *bus, int devfn, bool 
> multifunction,
>                                      const char *name);
>  PCIDevice *pci_create_simple_multifunction(PCIBus *bus, int devfn,
> -- 
> 1.7.9.111.gf3fb0
> 

-- 
yamahata