ARM: OMAP: Add clocksource driver for OMAP.
This is an update of
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=3876/1
from Daniel Walker and Kevin Hilman.
Changes from Dirk Behme:
- Apply cleanly to recent kernel (pt_regs change)
- Move clocksource init to extra function. Can be called
later by clocksource subsystem
- Remove warning: 'omap_32k_timer_handler' defined but
not used
when CONFIG_NO_IDLE_HZ isn't set.
- Minor cleanups
Changes from David Brownell:
- OMAP1, OMAP2: 32k clocksource is always available on
16xx and 24xx
- OMAP1 MPU timer:
* consult clock framework to determine xtal clock
* bugfix sched_clock() low order bits
* cleanup
- Kconfig updates
Note that "MPU timer" still doesn't have lost tick support.
Signed-off-by: David Brownell <[email protected]>
Signed-off-by: Dirk Behme <dirk.behme_at_gmail.com>
Index: linux-2.6.20-rc1/arch/arm/Kconfig
===================================================================
--- linux-2.6.20-rc1.orig/arch/arm/Kconfig
+++ linux-2.6.20-rc1/arch/arm/Kconfig
@@ -340,6 +340,7 @@ config ARCH_LH7A40X
config ARCH_OMAP
bool "TI OMAP"
+ select GENERIC_TIME
help
Support for TI's OMAP platform (OMAP1 and OMAP2).
Index: linux-2.6.20-rc1/arch/arm/plat-omap/common.c
===================================================================
--- linux-2.6.20-rc1.orig/arch/arm/plat-omap/common.c
+++ linux-2.6.20-rc1/arch/arm/plat-omap/common.c
@@ -156,3 +156,53 @@ static int __init omap_add_serial_consol
return add_preferred_console("ttyS", line, opt);
}
console_initcall(omap_add_serial_console);
+
+
+/*
+ * 32KHz clocksource ... always available, on pretty most chips except
+ * OMAP 730 and 1510. Other timers could be used as clocksources, with
+ * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
+ * but systems won't necessarily want to spend resources that way.
+ */
+
+#if defined(CONFIG_ARCH_OMAP16XX)
+#define TIMER_32K_SYNCHRONIZED 0xfffbc410
+#elif defined(CONFIG_ARCH_OMAP24XX)
+#define TIMER_32K_SYNCHRONIZED 0x48004010
+#endif
+
+#ifdef TIMER_32K_SYNCHRONIZED
+
+#include <linux/clocksource.h>
+
+static cycle_t omap_32k_read(void)
+{
+ return omap_readl(TIMER_32K_SYNCHRONIZED);
+}
+
+static struct clocksource clocksource_32k = {
+ .name = "32k_counter",
+ .rating = 250,
+ .read = omap_32k_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .shift = 10,
+ .is_continuous = 1,
+};
+
+static int __init omap_init_clocksource_32k(void)
+{
+ static char err[] __initdata = KERN_ERR
+ "%s: can't register clocksource!\n";
+
+ if (cpu_is_omap16xx() || cpu_is_omap24xx()) {
+ clocksource_32k.mult = clocksource_hz2mult(32768,
+ clocksource_32k.shift);
+
+ if (clocksource_register(&clocksource_32k))
+ printk(err, clocksource_32k.name);
+ }
+ return 0;
+}
+arch_initcall(omap_init_clocksource_32k);
+
+#endif /* TIMER_32K_SYNCHRONIZED */
Index: linux-2.6.20-rc1/arch/arm/plat-omap/timer32k.c
===================================================================
--- linux-2.6.20-rc1.orig/arch/arm/plat-omap/timer32k.c
+++ linux-2.6.20-rc1/arch/arm/plat-omap/timer32k.c
@@ -42,6 +42,7 @@
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/clk.h>
+#include <linux/clocksource.h>
#include <asm/system.h>
#include <asm/hardware.h>
@@ -171,15 +172,6 @@ omap_32k_ticks_to_nsecs(unsigned long ti
static unsigned long omap_32k_last_tick = 0;
/*
- * Returns elapsed usecs since last 32k timer interrupt
- */
-static unsigned long omap_32k_timer_gettimeoffset(void)
-{
- unsigned long now = omap_32k_sync_timer_read();
- return omap_32k_ticks_to_usecs(now - omap_32k_last_tick);
-}
-
-/*
* Returns current time from boot in nsecs. It's OK for this to wrap
* around for now, as it's just a relative time stamp.
*/
@@ -217,11 +209,6 @@ static inline irqreturn_t _omap_32k_time
return IRQ_HANDLED;
}
-static irqreturn_t omap_32k_timer_handler(int irq, void *dev_id)
-{
- return _omap_32k_timer_interrupt(irq, dev_id);
-}
-
static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
{
unsigned long flags;
@@ -234,6 +221,7 @@ static irqreturn_t omap_32k_timer_interr
}
#ifdef CONFIG_NO_IDLE_HZ
+
/*
* Programs the next timer interrupt needed. Called when dynamic tick is
* enabled, and to reprogram the ticks to skip from pm_idle. Note that
@@ -269,6 +257,22 @@ static int omap_32k_timer_disable_dyn_ti
return 0;
}
+static irqreturn_t omap_32k_timer_handler(int irq, void *dev_id)
+{
+ unsigned long now;
+
+ now = omap_32k_sync_timer_read();
+
+ /* Don't bother reprogramming timer if last tick was before next
+ * jiffie. We will get another interrupt when previously programmed
+ * timer expires. This cuts down interrupt load quite a bit.
+ */
+ if (now - omap_32k_last_tick < OMAP_32K_TICKS_PER_HZ)
+ return IRQ_HANDLED;
+
+ return _omap_32k_timer_interrupt(irq, dev_id);
+}
+
static struct dyn_tick_timer omap_dyn_tick_timer = {
.enable = omap_32k_timer_enable_dyn_tick,
.disable = omap_32k_timer_disable_dyn_tick,
@@ -291,7 +295,6 @@ static __init void omap_init_32k_timer(v
if (cpu_class_is_omap1())
setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
- omap_timer.offset = omap_32k_timer_gettimeoffset;
omap_32k_last_tick = omap_32k_sync_timer_read();
#ifdef CONFIG_ARCH_OMAP2
@@ -326,5 +329,4 @@ static void __init omap_timer_init(void)
struct sys_timer omap_timer = {
.init = omap_timer_init,
- .offset = NULL, /* Initialized later */
};
Index: linux-2.6.20-rc1/arch/arm/mach-omap1/time.c
===================================================================
--- linux-2.6.20-rc1.orig/arch/arm/mach-omap1/time.c
+++ linux-2.6.20-rc1/arch/arm/mach-omap1/time.c
@@ -39,6 +39,9 @@
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/clocksource.h>
#include <asm/system.h>
#include <asm/hardware.h>
@@ -48,13 +51,7 @@
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
-struct sys_timer omap_timer;
-/*
- * ---------------------------------------------------------------------------
- * MPU timer
- * ---------------------------------------------------------------------------
- */
#define OMAP_MPU_TIMER_BASE OMAP_MPU_TIMER1_BASE
#define OMAP_MPU_TIMER_OFFSET 0x100
@@ -88,21 +85,6 @@ static inline unsigned long long cycles_
return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
}
-/*
- * MPU_TICKS_PER_SEC must be an even number, otherwise machinecycles_to_usecs
- * will break. On P2, the timer count rate is 6.5 MHz after programming PTV
- * with 0. This divides the 13MHz input by 2, and is undocumented.
- */
-#if defined(CONFIG_MACH_OMAP_PERSEUS2) || defined(CONFIG_MACH_OMAP_FSAMPLE)
-/* REVISIT: This ifdef construct should be replaced by a query to clock
- * framework to see if timer base frequency is 12.0, 13.0 or 19.2 MHz.
- */
-#define MPU_TICKS_PER_SEC (13000000 / 2)
-#else
-#define MPU_TICKS_PER_SEC (12000000 / 2)
-#endif
-
-#define MPU_TIMER_TICK_PERIOD ((MPU_TICKS_PER_SEC / HZ) - 1)
typedef struct {
u32 cntl; /* CNTL_TIMER, R/W */
@@ -131,87 +113,94 @@ static inline void omap_mpu_timer_start(
timer->cntl = (MPU_TIMER_CLOCK_ENABLE | MPU_TIMER_AR | MPU_TIMER_ST);
}
-unsigned long omap_mpu_timer_ticks_to_usecs(unsigned long nr_ticks)
+/*
+ * ---------------------------------------------------------------------------
+ * MPU timer 1 ... count down to zero, interrupt, reload
+ * ---------------------------------------------------------------------------
+ */
+static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id)
{
- unsigned long long nsec;
+ write_seqlock(&xtime_lock);
+ /* NOTE: no lost-tick detection/handling! */
+ timer_tick();
+ write_sequnlock(&xtime_lock);
- nsec = cycles_2_ns((unsigned long long)nr_ticks);
- return (unsigned long)nsec / 1000;
+ return IRQ_HANDLED;
}
-/*
- * Last processed system timer interrupt
- */
-static unsigned long omap_mpu_timer_last = 0;
+static struct irqaction omap_mpu_timer1_irq = {
+ .name = "mpu_timer1",
+ .flags = IRQF_DISABLED | IRQF_TIMER,
+ .handler = omap_mpu_timer1_interrupt,
+};
-/*
- * Returns elapsed usecs since last system timer interrupt
- */
-static unsigned long omap_mpu_timer_gettimeoffset(void)
+static __init void omap_init_mpu_timer(unsigned long rate)
{
- unsigned long now = 0 - omap_mpu_timer_read(0);
- unsigned long elapsed = now - omap_mpu_timer_last;
+ set_cyc2ns_scale(rate / 1000);
- return omap_mpu_timer_ticks_to_usecs(elapsed);
+ setup_irq(INT_TIMER1, &omap_mpu_timer1_irq);
+ omap_mpu_timer_start(0, (rate / HZ) - 1);
}
/*
- * Elapsed time between interrupts is calculated using timer0.
- * Latency during the interrupt is calculated using timer1.
- * Both timer0 and timer1 are counting at 6MHz (P2 6.5MHz).
+ * ---------------------------------------------------------------------------
+ * MPU timer 2 ... free running 32-bit clock source and scheduler clock
+ * ---------------------------------------------------------------------------
*/
-static irqreturn_t omap_mpu_timer_interrupt(int irq, void *dev_id)
-{
- unsigned long now, latency;
- write_seqlock(&xtime_lock);
- now = 0 - omap_mpu_timer_read(0);
- latency = MPU_TICKS_PER_SEC / HZ - omap_mpu_timer_read(1);
- omap_mpu_timer_last = now - latency;
- timer_tick();
- write_sequnlock(&xtime_lock);
+static unsigned long omap_mpu_timer2_overflows;
+static irqreturn_t omap_mpu_timer2_interrupt(int irq, void *dev_id)
+{
+ omap_mpu_timer2_overflows++;
return IRQ_HANDLED;
}
-static struct irqaction omap_mpu_timer_irq = {
- .name = "mpu timer",
- .flags = IRQF_DISABLED | IRQF_TIMER,
- .handler = omap_mpu_timer_interrupt,
+static struct irqaction omap_mpu_timer2_irq = {
+ .name = "mpu_timer2",
+ .flags = IRQF_DISABLED,
+ .handler = omap_mpu_timer2_interrupt,
};
-static unsigned long omap_mpu_timer1_overflows;
-static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id)
+static cycle_t mpu_read(void)
{
- omap_mpu_timer1_overflows++;
- return IRQ_HANDLED;
+ return ~omap_mpu_timer_read(1);
}
-static struct irqaction omap_mpu_timer1_irq = {
- .name = "mpu timer1 overflow",
- .flags = IRQF_DISABLED,
- .handler = omap_mpu_timer1_interrupt,
+static struct clocksource clocksource_mpu = {
+ .name = "mpu_timer2",
+ .rating = 300,
+ .read = mpu_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .shift = 24,
+ .is_continuous = 1,
};
-static __init void omap_init_mpu_timer(void)
+static void __init omap_init_clocksource(unsigned long rate)
{
- set_cyc2ns_scale(MPU_TICKS_PER_SEC / 1000);
- omap_timer.offset = omap_mpu_timer_gettimeoffset;
- setup_irq(INT_TIMER1, &omap_mpu_timer1_irq);
- setup_irq(INT_TIMER2, &omap_mpu_timer_irq);
- omap_mpu_timer_start(0, 0xffffffff);
- omap_mpu_timer_start(1, MPU_TIMER_TICK_PERIOD);
+ static char err[] __initdata = KERN_ERR
+ "%s: can't register clocksource!\n";
+
+ clocksource_mpu.mult
+ = clocksource_khz2mult(rate/1000, clocksource_mpu.shift);
+
+ setup_irq(INT_TIMER2, &omap_mpu_timer2_irq);
+ omap_mpu_timer_start(1, ~0);
+
+ if (clocksource_register(&clocksource_mpu))
+ printk(err, clocksource_mpu.name);
}
+
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
- unsigned long ticks = 0 - omap_mpu_timer_read(0);
+ unsigned long ticks = 0 - omap_mpu_timer_read(1);
unsigned long long ticks64;
- ticks64 = omap_mpu_timer1_overflows;
+ ticks64 = omap_mpu_timer2_overflows;
ticks64 <<= 32;
ticks64 |= ticks;
@@ -225,10 +214,21 @@ unsigned long long sched_clock(void)
*/
static void __init omap_timer_init(void)
{
- omap_init_mpu_timer();
+ struct clk *ck_ref = clk_get(NULL, "ck_ref");
+ unsigned long rate;
+
+ BUG_ON(IS_ERR(ck_ref));
+
+ rate = clk_get_rate(ck_ref);
+ clk_put(ck_ref);
+
+ /* PTV = 0 */
+ rate /= 2;
+
+ omap_init_mpu_timer(rate);
+ omap_init_clocksource(rate);
}
struct sys_timer omap_timer = {
.init = omap_timer_init,
- .offset = NULL, /* Initialized later */
};
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