Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b067c904 authored by Linus Torvalds's avatar Linus Torvalds
Browse files
Pull parisc updates from Helge Deller:

 - added an optimized hash implementation for parisc (George Spelvin)

 - C99 style cleanups in iomap.c (Amitoj Kaur Chawla)

 - added breaks to switch statement in PDC function (noticed by Dan
   Carpenter)

* 'parisc-4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Change structure intialisation to C99 style in iomap.c
  parisc: Add break statements to pdc_pat_io_pci_cfg_read()
  parisc: Add <asm/hash.h>
parents 8e7106a6 a549c45a
Loading
Loading
Loading
Loading
+1 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ config PARISC
	select TTY # Needed for pdc_cons.c
	select HAVE_DEBUG_STACKOVERFLOW
	select HAVE_ARCH_AUDITSYSCALL
	select HAVE_ARCH_HASH
	select HAVE_ARCH_SECCOMP_FILTER
	select HAVE_ARCH_TRACEHOOK
	select HAVE_UNSTABLE_SCHED_CLOCK if (SMP || !64BIT)
+146 −0
Original line number Diff line number Diff line
#ifndef _ASM_HASH_H
#define _ASM_HASH_H

/*
 * HP-PA only implements integer multiply in the FPU.  However, for
 * integer multiplies by constant, it has a number of shift-and-add
 * (but no shift-and-subtract, sigh!) instructions that a compiler
 * can synthesize a code sequence with.
 *
 * Unfortunately, GCC isn't very efficient at using them.  For example
 * it uses three instructions for "x *= 21" when only two are needed.
 * But we can find a sequence manually.
 */

#define HAVE_ARCH__HASH_32 1

/*
 * This is a multiply by GOLDEN_RATIO_32 = 0x61C88647 optimized for the
 * PA7100 pairing rules.  This is an in-order 2-way superscalar processor.
 * Only one instruction in a pair may be a shift (by more than 3 bits),
 * but other than that, simple ALU ops (including shift-and-add by up
 * to 3 bits) may be paired arbitrarily.
 *
 * PA8xxx processors also dual-issue ALU instructions, although with
 * fewer constraints, so this schedule is good for them, too.
 *
 * This 6-step sequence was found by Yevgen Voronenko's implementation
 * of the Hcub algorithm at http://spiral.ece.cmu.edu/mcm/gen.html.
 */
static inline u32 __attribute_const__ __hash_32(u32 x)
{
	u32 a, b, c;

	/*
	 * Phase 1: Compute  a = (x << 19) + x,
	 * b = (x << 9) + a, c = (x << 23) + b.
	 */
	a = x << 19;		/* Two shifts can't be paired */
	b = x << 9;	a += x;
	c = x << 23;	b += a;
			c += b;
	/* Phase 2: Return (b<<11) + (c<<6) + (a<<3) - c */
	b <<= 11;
	a += c << 3;	b -= c;
	return (a << 3) + b;
}

#if BITS_PER_LONG == 64

#define HAVE_ARCH_HASH_64 1

/*
 * Finding a good shift-and-add chain for GOLDEN_RATIO_64 is tricky,
 * because available software for the purpose chokes on constants this
 * large.  (It's mostly designed for compiling FIR filter coefficients
 * into FPGAs.)
 *
 * However, Jason Thong pointed out a work-around.  The Hcub software
 * (http://spiral.ece.cmu.edu/mcm/gen.html) is designed for *multiple*
 * constant multiplication, and is good at finding shift-and-add chains
 * which share common terms.
 *
 * Looking at 0x0x61C8864680B583EB in binary:
 * 0110000111001000100001100100011010000000101101011000001111101011
 *  \______________/    \__________/       \_______/     \________/
 *   \____________________________/         \____________________/
 * you can see the non-zero bits are divided into several well-separated
 * blocks.  Hcub can find algorithms for those terms separately, which
 * can then be shifted and added together.
 *
 * Dividing the input into 2, 3 or 4 blocks, Hcub can find solutions
 * with 10, 9 or 8 adds, respectively, making a total of 11 for the
 * whole number.
 *
 * Using just two large blocks, 0xC3910C8D << 31 in the high bits,
 * and 0xB583EB in the low bits, produces as good an algorithm as any,
 * and with one more small shift than alternatives.
 *
 * The high bits are a larger number and more work to compute, as well
 * as needing one extra cycle to shift left 31 bits before the final
 * addition, so they are the critical path for scheduling.  The low bits
 * can fit into the scheduling slots left over.
 */


/*
 * This _ASSIGN(dst, src) macro performs "dst = src", but prevents GCC
 * from inferring anything about the value assigned to "dest".
 *
 * This prevents it from mis-optimizing certain sequences.
 * In particular, gcc is annoyingly eager to combine consecutive shifts.
 * Given "x <<= 19; y += x; z += x << 1;", GCC will turn this into
 * "y += x << 19; z += x << 20;" even though the latter sequence needs
 * an additional instruction and temporary register.
 *
 * Because no actual assembly code is generated, this construct is
 * usefully portable across all GCC platforms, and so can be test-compiled
 * on non-PA systems.
 *
 * In two places, additional unused input dependencies are added.  This
 * forces GCC's scheduling so it does not rearrange instructions too much.
 * Because the PA-8xxx is out of order, I'm not sure how much this matters,
 * but why make it more difficult for the processor than necessary?
 */
#define _ASSIGN(dst, src, ...) asm("" : "=r" (dst) : "0" (src), ##__VA_ARGS__)

/*
 * Multiply by GOLDEN_RATIO_64 = 0x0x61C8864680B583EB using a heavily
 * optimized shift-and-add sequence.
 *
 * Without the final shift, the multiply proper is 19 instructions,
 * 10 cycles and uses only 4 temporaries.  Whew!
 *
 * You are not expected to understand this.
 */
static __always_inline u32 __attribute_const__
hash_64(u64 a, unsigned int bits)
{
	u64 b, c, d;

	/*
	 * Encourage GCC to move a dynamic shift to %sar early,
	 * thereby freeing up an additional temporary register.
	 */
	if (!__builtin_constant_p(bits))
		asm("" : "=q" (bits) : "0" (64 - bits));
	else
		bits = 64 - bits;

	_ASSIGN(b, a*5);	c = a << 13;
	b = (b << 2) + a;	_ASSIGN(d, a << 17);
	a = b + (a << 1);	c += d;
	d = a << 10;		_ASSIGN(a, a << 19);
	d = a - d;		_ASSIGN(a, a << 4, "X" (d));
	c += b;			a += b;
	d -= c;			c += a << 1;
	a += c << 3;		_ASSIGN(b, b << (7+31), "X" (c), "X" (d));
	a <<= 31;		b += d;
	a += b;
	return a >> bits;
}
#undef _ASSIGN	/* We're a widely-used header file, so don't litter! */

#endif /* BITS_PER_LONG == 64 */

#endif /* _ASM_HASH_H */
+3 −3
Original line number Diff line number Diff line
@@ -1354,9 +1354,9 @@ int pdc_pat_io_pci_cfg_read(unsigned long pci_addr, int pci_size, u32 *mem_addr)
	retval = mem_pdc_call(PDC_PAT_IO, PDC_PAT_IO_PCI_CONFIG_READ,
					__pa(pdc_result), pci_addr, pci_size);
	switch(pci_size) {
		case 1: *(u8 *) mem_addr =  (u8)  pdc_result[0];
		case 2: *(u16 *)mem_addr =  (u16) pdc_result[0];
		case 4: *(u32 *)mem_addr =  (u32) pdc_result[0];
		case 1: *(u8 *) mem_addr =  (u8)  pdc_result[0]; break;
		case 2: *(u16 *)mem_addr =  (u16) pdc_result[0]; break;
		case 4: *(u32 *)mem_addr =  (u32) pdc_result[0]; break;
	}
	spin_unlock_irqrestore(&pdc_lock, flags);

+32 −32
Original line number Diff line number Diff line
@@ -125,22 +125,22 @@ static void ioport_write32r(void __iomem *addr, const void *s, unsigned long n)
}

static const struct iomap_ops ioport_ops = {
	ioport_read8,
	ioport_read16,
	ioport_read16,
	ioport_read32,
	ioport_read32,
	ioport_write8,
	ioport_write16,
	ioport_write16,
	ioport_write32,
	ioport_write32,
	ioport_read8r,
	ioport_read16r,
	ioport_read32r,
	ioport_write8r,
	ioport_write16r,
	ioport_write32r,
	.read8 = ioport_read8,
	.read16 = ioport_read16,
	.read16be = ioport_read16,
	.read32 = ioport_read32,
	.read32be = ioport_read32,
	.write8 = ioport_write8,
	.write16 = ioport_write16,
	.write16be = ioport_write16,
	.write32 = ioport_write32,
	.write32be = ioport_write32,
	.read8r = ioport_read8r,
	.read16r = ioport_read16r,
	.read32r = ioport_read32r,
	.write8r = ioport_write8r,
	.write16r = ioport_write16r,
	.write32r = ioport_write32r,
};

/* Legacy I/O memory ops */
@@ -244,22 +244,22 @@ static void iomem_write32r(void __iomem *addr, const void *s, unsigned long n)
}

static const struct iomap_ops iomem_ops = {
	iomem_read8,
	iomem_read16,
	iomem_read16be,
	iomem_read32,
	iomem_read32be,
	iomem_write8,
	iomem_write16,
	iomem_write16be,
	iomem_write32,
	iomem_write32be,
	iomem_read8r,
	iomem_read16r,
	iomem_read32r,
	iomem_write8r,
	iomem_write16r,
	iomem_write32r,
	.read8 = iomem_read8,
	.read16 = iomem_read16,
	.read16be = iomem_read16be,
	.read32 = iomem_read32,
	.read32be = iomem_read32be,
	.write8 = iomem_write8,
	.write16 = iomem_write16,
	.write16be = iomem_write16be,
	.write32 = iomem_write32,
	.write32be = iomem_write32be,
	.read8r = iomem_read8r,
	.read16r = iomem_read16r,
	.read32r = iomem_read32r,
	.write8r = iomem_write8r,
	.write16r = iomem_write16r,
	.write32r = iomem_write32r,
};

static const struct iomap_ops *iomap_ops[8] = {