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authorAndreas Larsson <andreas@gaisler.com>2014-08-29 17:09:18 +0200
committerDavid S. Miller <davem@davemloft.net>2014-09-10 01:39:10 +0200
commit384859d2af8ead22c9e5a570a4ab89f1b563c8e5 (patch)
tree753e436fd62f5eae28fdc099d2d6a5d7e9ba6c46 /arch/sparc/kernel/leon_kernel.c
parentsparc: Let memset return the address argument (diff)
downloadlinux-384859d2af8ead22c9e5a570a4ab89f1b563c8e5.tar.xz
linux-384859d2af8ead22c9e5a570a4ab89f1b563c8e5.zip
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.c31
1 files changed, 28 insertions, 3 deletions
diff --git a/arch/sparc/kernel/leon_kernel.c b/arch/sparc/kernel/leon_kernel.c
index 683c4af999de..9bbb8f2bbfcc 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)