Re: [PATCH 08/17] Introduce libio to common code for io read/write

Christoffer Dall
2014-02-02T02:24:48Z

On Tue, Jan 21, 2014 at 05:21:54PM +0100, Andrew Jones wrote:
> v3:
> - get rid of CONFIG_64BIT, replace with asserts
> - get rid of {read,write}_len()
> - fix bad *64_to_cpu macros

note that putting the changelog after the "---" prevents it from
getting committed, but I'm not sure if there are different
conventions for the unit-tests framework.

>
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
> lib/libio.h | 173 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 173 insertions(+)
> create mode 100644 lib/libio.h
>
> diff --git a/lib/libio.h b/lib/libio.h
> new file mode 100644
> index 0000000000000..6adc6a7bbee61
> --- /dev/null
> +++ b/lib/libio.h
> @@ -0,0 +1,173 @@
> +#ifndef _LIBIO_H_
> +#define _LIBIO_H_
> +/*
> + * Adapted from the Linux kernel's include/asm-generic/io.h and
> + * arch/arm/include/asm/io.h
> + */
> +#include "libcflat.h"
> +
> +#ifndef NDEBUG
> +#define LIBIO_ASSERT(expr) do { \
> + if (!(expr)) printf("%s:%d: assert failed!\n", __FILE__, __LINE__);\
> +} while (0)
> +#else
> +#define LIBIO_ASSERT(expr) do { } while (0)
> +#endif
> +
> +typedef u32 compat_ptr_t;
> +
> +/*
> + * Use compat_ptr() on 64-bit arches when casting 32-bit

arches? architectures? archs?

> + * addresses to pointers in order to avoid compiler warnings.
> + */
> +static inline void *compat_ptr(compat_ptr_t ptr)
> +{
> + return (void *)(unsigned long)ptr;
> +}
> +
> +static inline compat_ptr_t ptr_to_compat(void *ptr)
> +{
> + return (u32)(unsigned long)ptr;
> +}
> +
> +#ifndef __raw_readb
> +static inline u8 __raw_readb(const volatile void *addr)
> +{
> + return *(const volatile u8 *)addr;
> +}
> +#endif
> +
> +#ifndef __raw_readw
> +static inline u16 __raw_readw(const volatile void *addr)
> +{
> + return *(const volatile u16 *)addr;
> +}
> +#endif
> +
> +#ifndef __raw_readl
> +static inline u32 __raw_readl(const volatile void *addr)
> +{
> + return *(const volatile u32 *)addr;
> +}
> +#endif
> +
> +#ifndef __raw_readq
> +static inline u64 __raw_readq(const volatile void *addr)
> +{
> + LIBIO_ASSERT(sizeof(unsigned long) == sizeof(u64));
> + return *(const volatile u64 *)addr;
> +}
> +#endif
> +
> +#ifndef __raw_writeb
> +static inline void __raw_writeb(u8 b, volatile void *addr)
> +{
> + *(volatile u8 *)addr = b;
> +}
> +#endif
> +
> +#ifndef __raw_writew
> +static inline void __raw_writew(u16 b, volatile void *addr)
> +{
> + *(volatile u16 *)addr = b;
> +}
> +#endif
> +
> +#ifndef __raw_writel
> +static inline void __raw_writel(u32 b, volatile void *addr)
> +{
> + *(volatile u32 *)addr = b;
> +}
> +#endif
> +
> +#ifndef __raw_writeq
> +static inline void __raw_writeq(u64 b, volatile void *addr)
> +{
> + LIBIO_ASSERT(sizeof(unsigned long) == sizeof(u64));
> + *(volatile u64 *)addr = b;
> +}
> +#endif
> +
> +#ifndef __bswap16
> +static inline u16 __bswap16(u16 x)
> +{
> + return ((x >> 8) & 0xff) | ((x & 0xff) << 8);
> +}
> +#endif
> +
> +#ifndef __bswap32
> +static inline u32 __bswap32(u32 x)
> +{
> + return ((x & 0xff000000) >> 24) | ((x & 0x00ff0000) >> 8) |
> + ((x & 0x0000ff00) << 8) | ((x & 0x000000ff) << 24);
> +}
> +#endif
> +
> +#ifndef __bswap64
> +static inline u64 __bswap64(u64 x)
> +{
> + return ((x & 0x00000000000000ffULL) << 56) |
> + ((x & 0x000000000000ff00ULL) << 40) |
> + ((x & 0x0000000000ff0000ULL) << 24) |
> + ((x & 0x00000000ff000000ULL) << 8) |
> + ((x & 0x000000ff00000000ULL) >> 8) |
> + ((x & 0x0000ff0000000000ULL) >> 24) |
> + ((x & 0x00ff000000000000ULL) >> 40) |
> + ((x & 0xff00000000000000ULL) >> 56);
> +}
> +#endif
> +
> +#ifndef cpu_is_be
> +#define cpu_is_be 0
> +#endif
> +
> +#define le16_to_cpu(x) \
> + ({ u16 __r = cpu_is_be ? __bswap16(x) : (x); __r; })
> +#define cpu_to_le16 le16_to_cpu
> +
> +#define le32_to_cpu(x) \
> + ({ u32 __r = cpu_is_be ? __bswap32(x) : (x); __r; })
> +#define cpu_to_le32 le32_to_cpu
> +
> +#define le64_to_cpu(x) \
> + ({ u64 __r = cpu_is_be ? __bswap64(x) : (x); __r; })
> +#define cpu_to_le64 le64_to_cpu
> +
> +#define be16_to_cpu(x) \
> + ({ u16 __r = !cpu_is_be ? __bswap16(x) : (x); __r; })
> +#define cpu_to_be16 be16_to_cpu
> +
> +#define be32_to_cpu(x) \
> + ({ u32 __r = !cpu_is_be ? __bswap32(x) : (x); __r; })
> +#define cpu_to_be32 be32_to_cpu
> +
> +#define be64_to_cpu(x) \
> + ({ u64 __r = !cpu_is_be ? __bswap64(x) : (x); __r; })
> +#define cpu_to_be64 be64_to_cpu
> +
> +#ifndef rmb
> +#define rmb() do { } while (0)
> +#endif
> +#ifndef wmb
> +#define wmb() do { } while (0)
> +#endif
> +
> +#define readb(addr) \
> + ({ u8 __r = __raw_readb(addr); rmb(); __r; })
> +#define readw(addr) \
> + ({ u16 __r = le16_to_cpu(__raw_readw(addr)); rmb(); __r; })
> +#define readl(addr) \
> + ({ u32 __r = le32_to_cpu(__raw_readl(addr)); rmb(); __r; })
> +#define readq(addr) \
> + ({ u64 __r = le64_to_cpu(__raw_readq(addr)); rmb(); __r; })
> +
> +#define writeb(b, addr) \
> + ({ wmb(); __raw_writeb(b, addr); })
> +#define writew(b, addr) \
> + ({ wmb(); __raw_writew(cpu_to_le16(b), addr); })
> +#define writel(b, addr) \
> + ({ wmb(); __raw_writel(cpu_to_le32(b), addr); })
> +#define writeq(b, addr) \
> + ({ wmb(); __raw_writeq(cpu_to_le64(b), addr); })
> +
> +#endif

so these definitions always assume that your device is LE, which is
probably true for ARM and x86 for now, but if we ever use this on PPC or
want to test ARM BE with a BE QEMU, will it still work?

(There's some trickery with virtio and endianness that I don't remember
100%, so if we assume this ever only reads and writes to virtio space,
we may be in the clear.)

Otherwise:

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>