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Diffstat (limited to 'arch/tile/lib/spinlock_32.c')
-rw-r--r--arch/tile/lib/spinlock_32.c251
1 files changed, 0 insertions, 251 deletions
diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c
deleted file mode 100644
index db9333f2447c..000000000000
--- a/arch/tile/lib/spinlock_32.c
+++ /dev/null
@@ -1,251 +0,0 @@
-/*
- * Copyright 2010 Tilera Corporation. All Rights Reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation, version 2.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
- * NON INFRINGEMENT. See the GNU General Public License for
- * more details.
- */
-
-#include <linux/spinlock.h>
-#include <linux/module.h>
-#include <asm/processor.h>
-#include <arch/spr_def.h>
-
-#include "spinlock_common.h"
-
-void arch_spin_lock(arch_spinlock_t *lock)
-{
- int my_ticket;
- int iterations = 0;
- int delta;
-
- while ((my_ticket = __insn_tns((void *)&lock->next_ticket)) & 1)
- delay_backoff(iterations++);
-
- /* Increment the next ticket number, implicitly releasing tns lock. */
- lock->next_ticket = my_ticket + TICKET_QUANTUM;
-
- /* Wait until it's our turn. */
- while ((delta = my_ticket - lock->current_ticket) != 0)
- relax((128 / CYCLES_PER_RELAX_LOOP) * delta);
-}
-EXPORT_SYMBOL(arch_spin_lock);
-
-int arch_spin_trylock(arch_spinlock_t *lock)
-{
- /*
- * Grab a ticket; no need to retry if it's busy, we'll just
- * treat that the same as "locked", since someone else
- * will lock it momentarily anyway.
- */
- int my_ticket = __insn_tns((void *)&lock->next_ticket);
-
- if (my_ticket == lock->current_ticket) {
- /* Not currently locked, so lock it by keeping this ticket. */
- lock->next_ticket = my_ticket + TICKET_QUANTUM;
- /* Success! */
- return 1;
- }
-
- if (!(my_ticket & 1)) {
- /* Release next_ticket. */
- lock->next_ticket = my_ticket;
- }
-
- return 0;
-}
-EXPORT_SYMBOL(arch_spin_trylock);
-
-/*
- * The low byte is always reserved to be the marker for a "tns" operation
- * since the low bit is set to "1" by a tns. The next seven bits are
- * zeroes. The next byte holds the "next" writer value, i.e. the ticket
- * available for the next task that wants to write. The third byte holds
- * the current writer value, i.e. the writer who holds the current ticket.
- * If current == next == 0, there are no interested writers.
- */
-#define WR_NEXT_SHIFT _WR_NEXT_SHIFT
-#define WR_CURR_SHIFT _WR_CURR_SHIFT
-#define WR_WIDTH _WR_WIDTH
-#define WR_MASK ((1 << WR_WIDTH) - 1)
-
-/*
- * The last eight bits hold the active reader count. This has to be
- * zero before a writer can start to write.
- */
-#define RD_COUNT_SHIFT _RD_COUNT_SHIFT
-#define RD_COUNT_WIDTH _RD_COUNT_WIDTH
-#define RD_COUNT_MASK ((1 << RD_COUNT_WIDTH) - 1)
-
-
-/*
- * We can get the read lock if everything but the reader bits (which
- * are in the high part of the word) is zero, i.e. no active or
- * waiting writers, no tns.
- *
- * We guard the tns/store-back with an interrupt critical section to
- * preserve the semantic that the same read lock can be acquired in an
- * interrupt context.
- */
-int arch_read_trylock(arch_rwlock_t *rwlock)
-{
- u32 val;
- __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 1);
- val = __insn_tns((int *)&rwlock->lock);
- if (likely((val << _RD_COUNT_WIDTH) == 0)) {
- val += 1 << RD_COUNT_SHIFT;
- rwlock->lock = val;
- __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 0);
- BUG_ON(val == 0); /* we don't expect wraparound */
- return 1;
- }
- if ((val & 1) == 0)
- rwlock->lock = val;
- __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 0);
- return 0;
-}
-EXPORT_SYMBOL(arch_read_trylock);
-
-/*
- * Spin doing arch_read_trylock() until we acquire the lock.
- * ISSUE: This approach can permanently starve readers. A reader who sees
- * a writer could instead take a ticket lock (just like a writer would),
- * and atomically enter read mode (with 1 reader) when it gets the ticket.
- * This way both readers and writers would always make forward progress
- * in a finite time.
- */
-void arch_read_lock(arch_rwlock_t *rwlock)
-{
- u32 iterations = 0;
- while (unlikely(!arch_read_trylock(rwlock)))
- delay_backoff(iterations++);
-}
-EXPORT_SYMBOL(arch_read_lock);
-
-void arch_read_unlock(arch_rwlock_t *rwlock)
-{
- u32 val, iterations = 0;
-
- mb(); /* guarantee anything modified under the lock is visible */
- for (;;) {
- __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 1);
- val = __insn_tns((int *)&rwlock->lock);
- if (likely((val & 1) == 0)) {
- rwlock->lock = val - (1 << _RD_COUNT_SHIFT);
- __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 0);
- break;
- }
- __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 0);
- delay_backoff(iterations++);
- }
-}
-EXPORT_SYMBOL(arch_read_unlock);
-
-/*
- * We don't need an interrupt critical section here (unlike for
- * arch_read_lock) since we should never use a bare write lock where
- * it could be interrupted by code that could try to re-acquire it.
- */
-void arch_write_lock(arch_rwlock_t *rwlock)
-{
- /*
- * The trailing underscore on this variable (and curr_ below)
- * reminds us that the high bits are garbage; we mask them out
- * when we compare them.
- */
- u32 my_ticket_;
- u32 iterations = 0;
- u32 val = __insn_tns((int *)&rwlock->lock);
-
- if (likely(val == 0)) {
- rwlock->lock = 1 << _WR_NEXT_SHIFT;
- return;
- }
-
- /*
- * Wait until there are no readers, then bump up the next
- * field and capture the ticket value.
- */
- for (;;) {
- if (!(val & 1)) {
- if ((val >> RD_COUNT_SHIFT) == 0)
- break;
- rwlock->lock = val;
- }
- delay_backoff(iterations++);
- val = __insn_tns((int *)&rwlock->lock);
- }
-
- /* Take out the next ticket and extract my ticket value. */
- rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT);
- my_ticket_ = val >> WR_NEXT_SHIFT;
-
- /* Wait until the "current" field matches our ticket. */
- for (;;) {
- u32 curr_ = val >> WR_CURR_SHIFT;
- u32 delta = ((my_ticket_ - curr_) & WR_MASK);
- if (likely(delta == 0))
- break;
-
- /* Delay based on how many lock-holders are still out there. */
- relax((256 / CYCLES_PER_RELAX_LOOP) * delta);
-
- /*
- * Get a non-tns value to check; we don't need to tns
- * it ourselves. Since we're not tns'ing, we retry
- * more rapidly to get a valid value.
- */
- while ((val = rwlock->lock) & 1)
- relax(4);
- }
-}
-EXPORT_SYMBOL(arch_write_lock);
-
-int arch_write_trylock(arch_rwlock_t *rwlock)
-{
- u32 val = __insn_tns((int *)&rwlock->lock);
-
- /*
- * If a tns is in progress, or there's a waiting or active locker,
- * or active readers, we can't take the lock, so give up.
- */
- if (unlikely(val != 0)) {
- if (!(val & 1))
- rwlock->lock = val;
- return 0;
- }
-
- /* Set the "next" field to mark it locked. */
- rwlock->lock = 1 << _WR_NEXT_SHIFT;
- return 1;
-}
-EXPORT_SYMBOL(arch_write_trylock);
-
-void arch_write_unlock(arch_rwlock_t *rwlock)
-{
- u32 val, eq, mask;
-
- mb(); /* guarantee anything modified under the lock is visible */
- val = __insn_tns((int *)&rwlock->lock);
- if (likely(val == (1 << _WR_NEXT_SHIFT))) {
- rwlock->lock = 0;
- return;
- }
- while (unlikely(val & 1)) {
- /* Limited backoff since we are the highest-priority task. */
- relax(4);
- val = __insn_tns((int *)&rwlock->lock);
- }
- mask = 1 << WR_CURR_SHIFT;
- val = __insn_addb(val, mask);
- eq = __insn_seqb(val, val << (WR_CURR_SHIFT - WR_NEXT_SHIFT));
- val = __insn_mz(eq & mask, val);
- rwlock->lock = val;
-}
-EXPORT_SYMBOL(arch_write_unlock);