[PATCH 3/3] arm64: enable 128-bit memory read/write support

Yury Norov
2018-01-24T09:05:19Z

Introduce __raw_writeo(), __raw_reado() and other arch-specific
RW functions for 128-bit memory access, and enable it for arm64.

128-bit I/O is required for example by Octeon TX2 device to access
some registers. According to Hardware Reference Manual:

A 128-bit write to the OP_FREE0/1 registers frees a pointer into a
given [...] pool. All other accesses to these registers (e.g. reads
and 64-bit writes) are RAZ/WI.

Starting from ARMv8.4, stp and ldp instructions become atomic, and
API for 128-bit access would be helpful for core code.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
arch/Kconfig | 7 +++++++
arch/arm64/include/asm/io.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index 76c0b54443b1..2baff7de405d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -116,6 +116,13 @@ config UPROBES
managed by the kernel and kept transparent to the probed
application. )

+config HAVE_128BIT_ACCESS
+ def_bool ARM64
+ help
+ Architectures having 128-bit access require corresponding APIs,
+ like reado() and writeo(), which stands for reading and writing
+ the octet of bytes at once.
+
config HAVE_64BIT_ALIGNED_ACCESS
def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
help
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 35b2e50f17fb..7c5d834abfd8 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -60,6 +60,18 @@ static inline void __raw_writeq(u64 val, volatile void __iomem *addr)
asm volatile("str %x0, [%1]" : : "rZ" (val), "r" (addr));
}

+#define __raw_writeo __raw_writeo
+static inline void __raw_writeo(__uint128_t val, volatile void __iomem *addr)
+{
+ u64 l = (u64) val;
+ u64 h = (u64) (val >> 64);
+ __uint128_t *__addr = (__uint128_t *) addr;
+
+ asm volatile("stp %x[x0], %x[x1], %x[p1]"
+ : [p1]"=Ump"(*__addr)
+ : [x0]"r"(l), [x1]"r"(h));
+}
+
#define __raw_readb __raw_readb
static inline u8 __raw_readb(const volatile void __iomem *addr)
{
@@ -105,6 +117,19 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
return val;
}

+#define __raw_reado __raw_reado
+static inline __uint128_t __raw_reado(const volatile void __iomem *addr)
+{
+ u64 l, h;
+ __uint128_t *__addr = (__uint128_t *) addr;
+
+ asm volatile("ldp %x[x0], %x[x1], %x[p1]"
+ : [x0]"=r"(l), [x1]"=r"(h)
+ : [p1]"Ump"(*__addr));
+
+ return (__uint128_t) l | ((__uint128_t) h) << 64;
+}
+
/* IO barriers */
#define __iormb() rmb()
#define __iowmb() wmb()
@@ -120,11 +145,13 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
#define readw_relaxed(c) ({ u16 __r = le16_to_cpu((__force __le16)__raw_readw(c)); __r; })
#define readl_relaxed(c) ({ u32 __r = le32_to_cpu((__force __le32)__raw_readl(c)); __r; })
#define readq_relaxed(c) ({ u64 __r = le64_to_cpu((__force __le64)__raw_readq(c)); __r; })
+#define reado_relaxed(c) ({ __uint128_t __r = le128_to_cpu((__force __le128)__raw_reado(c)); __r; })

#define writeb_relaxed(v,c) ((void)__raw_writeb((v),(c)))
#define writew_relaxed(v,c) ((void)__raw_writew((__force u16)cpu_to_le16(v),(c)))
#define writel_relaxed(v,c) ((void)__raw_writel((__force u32)cpu_to_le32(v),(c)))
#define writeq_relaxed(v,c) ((void)__raw_writeq((__force u64)cpu_to_le64(v),(c)))
+#define writeo_relaxed(v,c) ((void)__raw_writeo((__force __uint128_t)cpu_to_le128(v),(c)))

/*
* I/O memory access primitives. Reads are ordered relative to any
@@ -135,11 +162,13 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
#define readw(c) ({ u16 __v = readw_relaxed(c); __iormb(); __v; })
#define readl(c) ({ u32 __v = readl_relaxed(c); __iormb(); __v; })
#define readq(c) ({ u64 __v = readq_relaxed(c); __iormb(); __v; })
+#define reado(c) ({ __uint128_t __v = reado_relaxed(c); __iormb(); __v; })

#define writeb(v,c) ({ __iowmb(); writeb_relaxed((v),(c)); })
#define writew(v,c) ({ __iowmb(); writew_relaxed((v),(c)); })
#define writel(v,c) ({ __iowmb(); writel_relaxed((v),(c)); })
#define writeq(v,c) ({ __iowmb(); writeq_relaxed((v),(c)); })
+#define writeo(v,c) ({ __iowmb(); writeo_relaxed((v),(c)); })

/*
* I/O port access primitives.
@@ -188,10 +217,12 @@ extern void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size);
#define ioread16be(p) ({ __u16 __v = be16_to_cpu((__force __be16)__raw_readw(p)); __iormb(); __v; })
#define ioread32be(p) ({ __u32 __v = be32_to_cpu((__force __be32)__raw_readl(p)); __iormb(); __v; })
#define ioread64be(p) ({ __u64 __v = be64_to_cpu((__force __be64)__raw_readq(p)); __iormb(); __v; })
+#define ioread128be(p) ({ __uint128_t __v = be128_to_cpu((__force __be128)__raw_readq(p)); __iormb(); __v; })

#define iowrite16be(v,p) ({ __iowmb(); __raw_writew((__force __u16)cpu_to_be16(v), p); })
#define iowrite32be(v,p) ({ __iowmb(); __raw_writel((__force __u32)cpu_to_be32(v), p); })
#define iowrite64be(v,p) ({ __iowmb(); __raw_writeq((__force __u64)cpu_to_be64(v), p); })
+#define iowrite128be(v,p) ({ __iowmb(); __raw_writeo((__force __u128)cpu_to_be128(v), p); })

#include <asm-generic/io.h>

--
2.11.0