[Blackfin] arch: initial generic time and clock sources
This patch enables Hight-Res Timers and tickless kernel
Signed-off-by: Vitja Makarov <vitja.makarov@gmail.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 2dd1f30..a3cf9d0 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -47,10 +47,6 @@
bool
default y
-config GENERIC_TIME
- bool
- default n
-
config GENERIC_GPIO
bool
default y
@@ -415,6 +411,30 @@
source kernel/Kconfig.hz
+config GENERIC_TIME
+ bool "Generic time"
+ default y
+
+config GENERIC_CLOCKEVENTS
+ bool "Generic clock events"
+ depends on GENERIC_TIME
+ default y
+
+config CYCLES_CLOCKSOURCE
+ bool "Use 'CYCLES' as a clocksource (EXPERIMENTAL)"
+ depends on EXPERIMENTAL
+ depends on GENERIC_CLOCKEVENTS
+ depends on !BFIN_SCRATCH_REG_CYCLES
+ default n
+ help
+ If you say Y here, you will enable support for using the 'cycles'
+ registers as a clock source. Doing so means you will be unable to
+ safely write to the 'cycles' register during runtime. You will
+ still be able to read it (such as for performance monitoring), but
+ writing the registers will most likely crash the kernel.
+
+source kernel/time/Kconfig
+
comment "Memory Setup"
config MEM_SIZE
diff --git a/arch/blackfin/kernel/Makefile b/arch/blackfin/kernel/Makefile
index 318b9b6..6140cd6 100644
--- a/arch/blackfin/kernel/Makefile
+++ b/arch/blackfin/kernel/Makefile
@@ -6,9 +6,15 @@
obj-y := \
entry.o process.o bfin_ksyms.o ptrace.o setup.o signal.o \
- sys_bfin.o time.o traps.o irqchip.o dma-mapping.o flat.o \
+ sys_bfin.o traps.o irqchip.o dma-mapping.o flat.o \
fixed_code.o reboot.o bfin_gpio.o
+ifeq ($(CONFIG_GENERIC_CLOCKEVENTS),y)
+ obj-y += time-ts.o
+else
+ obj-y += time.o
+endif
+
obj-$(CONFIG_BFIN_GPTIMERS) += gptimers.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_BFIN_DMA_5XX) += bfin_dma_5xx.o
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index 6b8459c6..6dedb2d 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -32,6 +32,8 @@
#include <linux/unistd.h>
#include <linux/user.h>
#include <linux/uaccess.h>
+#include <linux/sched.h>
+#include <linux/tick.h>
#include <linux/fs.h>
#include <linux/err.h>
@@ -69,33 +71,44 @@
* The idle loop on BFIN
*/
#ifdef CONFIG_IDLE_L1
-void default_idle(void)__attribute__((l1_text));
+static void default_idle(void)__attribute__((l1_text));
void cpu_idle(void)__attribute__((l1_text));
#endif
-void default_idle(void)
+/*
+ * This is our default idle handler. We need to disable
+ * interrupts here to ensure we don't miss a wakeup call.
+ */
+static void default_idle(void)
{
- while (!need_resched()) {
- local_irq_disable();
- if (likely(!need_resched()))
- idle_with_irq_disabled();
- local_irq_enable();
- }
+ local_irq_disable();
+ if (!need_resched())
+ idle_with_irq_disabled();
+
+ local_irq_enable();
}
-void (*idle)(void) = default_idle;
-
/*
- * The idle thread. There's no useful work to be
- * done, so just try to conserve power and have a
- * low exit latency (ie sit in a loop waiting for
- * somebody to say that they'd like to reschedule)
+ * The idle thread. We try to conserve power, while trying to keep
+ * overall latency low. The architecture specific idle is passed
+ * a value to indicate the level of "idleness" of the system.
*/
void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
- idle();
+ void (*idle)(void) = pm_idle;
+
+#ifdef CONFIG_HOTPLUG_CPU
+ if (cpu_is_offline(smp_processor_id()))
+ cpu_die();
+#endif
+ if (!idle)
+ idle = default_idle;
+ tick_nohz_stop_sched_tick();
+ while (!need_resched())
+ idle();
+ tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();
preempt_disable();
diff --git a/arch/blackfin/kernel/time-ts.c b/arch/blackfin/kernel/time-ts.c
new file mode 100644
index 0000000..3aad6d7
--- /dev/null
+++ b/arch/blackfin/kernel/time-ts.c
@@ -0,0 +1,194 @@
+/*
+ * linux/arch/kernel/time-ts.c
+ *
+ * Based on arm clockevents implementation and old bfin time tick.
+ *
+ * Copyright(C) 2008, GeoTechnologies, Vitja Makarov
+ *
+ * This code is licenced under the GPL version 2. For details see
+ * kernel-base/COPYING.
+ */
+#include <linux/module.h>
+#include <linux/profile.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/irq.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+
+#include <asm/blackfin.h>
+
+#ifdef CONFIG_CYCLES_CLOCKSOURCE
+
+static unsigned long cyc2ns_scale;
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+
+static inline void set_cyc2ns_scale(unsigned long cpu_khz)
+{
+ cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
+}
+
+static inline unsigned long long cycles_2_ns(cycle_t cyc)
+{
+ return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
+}
+
+static cycle_t read_cycles(void)
+{
+ unsigned long tmp, tmp2;
+ asm("%0 = cycles; %1 = cycles2;" : "=d"(tmp), "=d"(tmp2));
+ return tmp | ((cycle_t)tmp2 << 32);
+}
+
+unsigned long long sched_clock(void)
+{
+ return cycles_2_ns(read_cycles());
+}
+
+static struct clocksource clocksource_bfin = {
+ .name = "bfin_cycles",
+ .rating = 350,
+ .read = read_cycles,
+ .mask = CLOCKSOURCE_MASK(64),
+ .shift = 22,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init bfin_clocksource_init(void)
+{
+ set_cyc2ns_scale(get_cclk() / 1000);
+
+ clocksource_bfin.mult = clocksource_hz2mult(get_cclk(), clocksource_bfin.shift);
+
+ if (clocksource_register(&clocksource_bfin))
+ panic("failed to register clocksource");
+
+ return 0;
+}
+
+#else
+# define bfin_clocksource_init()
+#endif
+
+static int bfin_timer_set_next_event(unsigned long cycles,
+ struct clock_event_device *evt)
+{
+ bfin_write_TCOUNT(cycles);
+ CSYNC();
+ return 0;
+}
+
+static void bfin_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC: {
+ unsigned long tcount = ((get_cclk() / (HZ * 1)) - 1);
+ bfin_write_TCNTL(TMPWR);
+ CSYNC();
+ bfin_write_TPERIOD(tcount);
+ bfin_write_TCOUNT(tcount);
+ bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD);
+ CSYNC();
+ break;
+ }
+ case CLOCK_EVT_MODE_ONESHOT:
+ bfin_write_TCOUNT(0);
+ bfin_write_TCNTL(TMPWR | TMREN);
+ CSYNC();
+ break;
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ bfin_write_TCNTL(0);
+ CSYNC();
+ break;
+ case CLOCK_EVT_MODE_RESUME:
+ break;
+ }
+}
+
+static void __init bfin_timer_init(void)
+{
+ /* power up the timer, but don't enable it just yet */
+ bfin_write_TCNTL(TMPWR);
+ CSYNC();
+
+ /*
+ * the TSCALE prescaler counter.
+ */
+ bfin_write_TSCALE(0);
+ bfin_write_TPERIOD(0);
+ bfin_write_TCOUNT(0);
+
+ /* now enable the timer */
+ CSYNC();
+}
+
+/*
+ * timer_interrupt() needs to keep up the real-time clock,
+ * as well as call the "do_timer()" routine every clocktick
+ */
+#ifdef CONFIG_CORE_TIMER_IRQ_L1
+__attribute__((l1_text))
+#endif
+irqreturn_t timer_interrupt(int irq, void *dev_id);
+
+static struct clock_event_device clockevent_bfin = {
+ .name = "bfin_core_timer",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .shift = 32,
+ .cpumask = CPU_MASK_CPU0,
+ .set_next_event = bfin_timer_set_next_event,
+ .set_mode = bfin_timer_set_mode,
+};
+
+static struct irqaction bfin_timer_irq = {
+ .name = "Blackfin Core Timer",
+ .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = timer_interrupt,
+ .dev_id = &clockevent_bfin,
+};
+
+irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+ evt->event_handler(evt);
+ return IRQ_HANDLED;
+}
+
+static int __init bfin_clockevent_init(void)
+{
+ setup_irq(IRQ_CORETMR, &bfin_timer_irq);
+ bfin_timer_init();
+
+ clockevent_bfin.mult = div_sc(get_cclk(), NSEC_PER_SEC, clockevent_bfin.shift);
+ clockevent_bfin.max_delta_ns = clockevent_delta2ns(-1, &clockevent_bfin);
+ clockevent_bfin.min_delta_ns = clockevent_delta2ns(100, &clockevent_bfin);
+ clockevents_register_device(&clockevent_bfin);
+
+ return 0;
+}
+
+void __init time_init(void)
+{
+ time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
+
+#ifdef CONFIG_RTC_DRV_BFIN
+ /* [#2663] hack to filter junk RTC values that would cause
+ * userspace to have to deal with time values greater than
+ * 2^31 seconds (which uClibc cannot cope with yet)
+ */
+ if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
+ printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
+ bfin_write_RTC_STAT(0);
+ }
+#endif
+
+ /* Initialize xtime. From now on, xtime is updated with timer interrupts */
+ xtime.tv_sec = secs_since_1970;
+ xtime.tv_nsec = 0;
+ set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
+
+ bfin_clocksource_init();
+ bfin_clockevent_init();
+}