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| author | Andreas Larsson <andreas@gaisler.com> | 2014-08-29 15:09:18 (GMT) |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-09 23:39:10 (GMT) |
| commit | 384859d2af8ead22c9e5a570a4ab89f1b563c8e5 (patch) | |
| tree | 753e436fd62f5eae28fdc099d2d6a5d7e9ba6c46 /arch/sparc/kernel/leon_kernel.c | |
| parent | 74cad25c076a2f5253312c2fe82d1a4daecc1323 (diff) | |
| download | linux-384859d2af8ead22c9e5a570a4ab89f1b563c8e5.tar.xz | |
sparc: leon: Fix race condition between leon_cycles_offset and timer_interrupt
This makes sure that leon_cycles_offset takes the pending bit into
account and that leon_clear_clock_irq clears the pending bit. Otherwise,
if leon_cycles_offset is executed after the timer has wrapped but before
timer_interrupt has increased timer_cs_internal_counter, time can be
perceived to go backwards.
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/kernel/leon_kernel.c')
| -rw-r--r-- | arch/sparc/kernel/leon_kernel.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/arch/sparc/kernel/leon_kernel.c b/arch/sparc/kernel/leon_kernel.c index 683c4af..9bbb8f2 100644 --- a/arch/sparc/kernel/leon_kernel.c +++ b/arch/sparc/kernel/leon_kernel.c @@ -37,6 +37,7 @@ unsigned long amba_system_id; static DEFINE_SPINLOCK(leon_irq_lock); static unsigned long leon3_gptimer_idx; /* Timer Index (0..6) within Timer Core */ +static unsigned long leon3_gptimer_ackmask; /* For clearing pending bit */ unsigned long leon3_gptimer_irq; /* interrupt controller irq number */ unsigned int sparc_leon_eirq; #define LEON_IMASK(cpu) (&leon3_irqctrl_regs->mask[cpu]) @@ -260,11 +261,19 @@ void leon_update_virq_handling(unsigned int virq, static u32 leon_cycles_offset(void) { - u32 rld, val, off; + u32 rld, val, ctrl, off; + rld = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].rld); val = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].val); - off = rld - val; - return rld - val; + ctrl = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].ctrl); + if (LEON3_GPTIMER_CTRL_ISPENDING(ctrl)) { + val = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].val); + off = 2 * rld - val; + } else { + off = rld - val; + } + + return off; } #ifdef CONFIG_SMP @@ -302,6 +311,7 @@ void __init leon_init_timers(void) int ampopts; int err; u32 config; + u32 ctrl; sparc_config.get_cycles_offset = leon_cycles_offset; sparc_config.cs_period = 1000000 / HZ; @@ -374,6 +384,16 @@ void __init leon_init_timers(void) if (!(leon3_gptimer_regs && leon3_irqctrl_regs && leon3_gptimer_irq)) goto bad; + ctrl = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].ctrl); + LEON3_BYPASS_STORE_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].ctrl, + ctrl | LEON3_GPTIMER_CTRL_PENDING); + ctrl = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].ctrl); + + if ((ctrl & LEON3_GPTIMER_CTRL_PENDING) != 0) + leon3_gptimer_ackmask = ~LEON3_GPTIMER_CTRL_PENDING; + else + leon3_gptimer_ackmask = ~0; + LEON3_BYPASS_STORE_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].val, 0); LEON3_BYPASS_STORE_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].rld, (((1000000 / HZ) - 1))); @@ -452,6 +472,11 @@ bad: static void leon_clear_clock_irq(void) { + u32 ctrl; + + ctrl = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].ctrl); + LEON3_BYPASS_STORE_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].ctrl, + ctrl & leon3_gptimer_ackmask); } static void leon_load_profile_irq(int cpu, unsigned int limit) |