@@ -225,7 +225,8 @@ void __init omap_dmtimer_init(void)
static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
int gptimer_id,
const char *fck_source,
- const char *property)
+ const char *property,
+ int posted)
{
char name[10]; /* 10 = sizeof("gptXX_Xck0") */
const char *oh_name;
@@ -311,10 +312,15 @@ static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
}
__omap_dm_timer_init_regs(timer);
__omap_dm_timer_reset(timer, 1, 1);
- timer->posted = 1;
- timer->rate = clk_get_rate(timer->fclk);
+ if (posted)
+ omap_dm_timer_enable_posted(timer);
+ /* Check that the intended posted configuration matches the actual */
+ if (posted != timer->posted)
+ return -EINVAL;
+
+ timer->rate = clk_get_rate(timer->fclk);
timer->reserved = 1;
return res;
@@ -326,7 +332,17 @@ static void __init omap2_gp_clockevent_init(int gptimer_id,
{
int res;
- res = omap_dm_timer_init_one(&clkev, gptimer_id, fck_source, property);
+ omap_dm_timer_populate_errata(&clkev);
+
+ /*
+ * For clock-event timers we never read the timer counter and
+ * so we are not impacted by errata i103 and i767. Therefore,
+ * we can safely ignore this errata for clock-event timers.
+ */
+ omap_dm_timer_override_errata(&clkev, OMAP_TIMER_ERRATA_I103_I767);
+
+ res = omap_dm_timer_init_one(&clkev, gptimer_id, fck_source, property,
+ OMAP_TIMER_POSTED);
BUG_ON(res);
omap2_gp_timer_irq.dev_id = &clkev;
@@ -360,7 +376,7 @@ static bool use_gptimer_clksrc;
static cycle_t clocksource_read_cycles(struct clocksource *cs)
{
return (cycle_t)__omap_dm_timer_read_counter(&clksrc,
- OMAP_TIMER_POSTED);
+ OMAP_TIMER_NONPOSTED);
}
static struct clocksource clocksource_gpt = {
@@ -375,7 +391,7 @@ static u32 notrace dmtimer_read_sched_clock(void)
{
if (clksrc.reserved)
return __omap_dm_timer_read_counter(&clksrc,
- OMAP_TIMER_POSTED);
+ OMAP_TIMER_NONPOSTED);
return 0;
}
@@ -453,12 +469,15 @@ static void __init omap2_gptimer_clocksource_init(int gptimer_id,
{
int res;
- res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source, NULL);
+ omap_dm_timer_populate_errata(&clksrc);
+
+ res = omap_dm_timer_init_one(&clksrc, gptimer_id, fck_source, NULL,
+ OMAP_TIMER_NONPOSTED);
BUG_ON(res);
__omap_dm_timer_load_start(&clksrc,
OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR, 0,
- OMAP_TIMER_POSTED);
+ OMAP_TIMER_NONPOSTED);
setup_sched_clock(dmtimer_read_sched_clock, 32, clksrc.rate);
if (clocksource_register_hz(&clocksource_gpt, clksrc.rate))
@@ -43,6 +43,7 @@
#include <linux/of.h>
#include <linux/of_device.h>
+#include <plat/cpu.h>
#include <plat/dmtimer.h>
static u32 omap_reserved_systimers;
@@ -128,8 +129,8 @@ static void omap_dm_timer_reset(struct omap_dm_timer *timer)
}
__omap_dm_timer_reset(timer, 0, 0);
+ omap_dm_timer_enable_posted(timer);
omap_dm_timer_disable(timer);
- timer->posted = 1;
}
int omap_dm_timer_prepare(struct omap_dm_timer *timer)
@@ -173,6 +174,61 @@ int omap_dm_timer_reserve_systimer(int id)
return 0;
}
+/**
+ * omap_dm_timer_populate_errata - populate errata flags for a timer
+ * @timer: pointer to timer handle
+ *
+ * For a given timer, populate the timer errata flags that are specific to the
+ * OMAP device being used.
+ */
+void omap_dm_timer_populate_errata(struct omap_dm_timer *timer)
+{
+ timer->errata = 0;
+
+ if (cpu_class_is_omap1() || cpu_is_omap24xx())
+ return;
+
+ timer->errata = OMAP_TIMER_ERRATA_I103_I767;
+}
+
+/**
+ * omap_dm_timer_override_errata - override errata flags for a timer
+ * @timer: pointer to timer handle
+ * @errata: errata flags to be ignored
+ *
+ * For a given timer, override a timer errata by clearing the flags specified
+ * by the errata argument. A specific erratum should only be overridden for a
+ * timer if the timer is used in such a way the erratum has no impact.
+ */
+void omap_dm_timer_override_errata(struct omap_dm_timer *timer, u32 errata)
+{
+ timer->errata &= ~errata;
+}
+
+/*
+ * omap_dm_timer_enable_posted - enables write posted mode
+ * @timer: pointer to timer instance handle
+ *
+ * Enables the write posted mode for the timer. When posted mode is enabled
+ * writes to certain timer registers are immediately acknowledged by the
+ * internal bus and hence prevents stalling the CPU waiting for the write to
+ * complete. Enabling this feature can improve performance for writing to the
+ * timer registers.
+ */
+void omap_dm_timer_enable_posted(struct omap_dm_timer *timer)
+{
+ if (timer->posted)
+ return;
+
+ if (timer->errata & OMAP_TIMER_ERRATA_I103_I767)
+ return;
+
+ omap_dm_timer_write_reg(timer, OMAP_TIMER_IF_CTRL_REG,
+ OMAP_TIMER_CTRL_POSTED);
+ timer->context.tsicr = OMAP_TIMER_CTRL_POSTED;
+ timer->posted = OMAP_TIMER_POSTED;
+}
+
struct omap_dm_timer *omap_dm_timer_request(void)
{
struct omap_dm_timer *timer = NULL, *t;
@@ -805,6 +861,8 @@ static int __devinit omap_dm_timer_probe(struct platform_device *pdev)
timer->irq = irq->start;
timer->pdev = pdev;
+ omap_dm_timer_populate_errata(timer);
+
/* Skip pm_runtime_enable for OMAP1 */
if (!(timer->capability & OMAP_TIMER_NEEDS_RESET)) {
pm_runtime_enable(dev);
@@ -66,6 +66,16 @@
#define OMAP_TIMER_NEEDS_RESET 0x10000000
#define OMAP_TIMER_HAS_DSP_IRQ 0x08000000
+/*
+ * timer errata flags
+ *
+ * Errata i103/i767 impacts all OMAP3/4/5 devices including AM33xx. This
+ * errata prevents us from using posted mode on these devices, unless the
+ * timer counter register is never read. For more details please refer to
+ * the OMAP3/4/5 errata documents.
+ */
+#define OMAP_TIMER_ERRATA_I103_I767 0x80000000
+
struct omap_timer_capability_dev_attr {
u32 timer_capability;
};
@@ -102,6 +112,9 @@ struct dmtimer_platform_data {
};
int omap_dm_timer_reserve_systimer(int id);
+void omap_dm_timer_populate_errata(struct omap_dm_timer *timer);
+void omap_dm_timer_override_errata(struct omap_dm_timer *timer, u32 errata);
+void omap_dm_timer_enable_posted(struct omap_dm_timer *timer);
struct omap_dm_timer *omap_dm_timer_request(void);
struct omap_dm_timer *omap_dm_timer_request_specific(int timer_id);
struct omap_dm_timer *omap_dm_timer_request_by_cap(u32 cap);
@@ -273,6 +286,7 @@ struct omap_dm_timer {
int ctx_loss_count;
int revision;
u32 capability;
+ u32 errata;
struct platform_device *pdev;
struct list_head node;
};
@@ -344,10 +358,6 @@ static inline void __omap_dm_timer_reset(struct omap_dm_timer *timer,
l |= 1 << 2;
__raw_writel(l, timer->io_base + OMAP_TIMER_OCP_CFG_OFFSET);
-
- /* Match hardware reset default of posted mode */
- __omap_dm_timer_write(timer, OMAP_TIMER_IF_CTRL_REG,
- OMAP_TIMER_CTRL_POSTED, 0);
}
static inline int __omap_dm_timer_set_source(struct clk *timer_fck,