iop: clocksource support
This updates the IOP platform to expose the free-running
timer 1 as a clocksource object. This timer is now also
properly initialised, which requires a new write_tcr1()
function from the mach-specific code. Apart from the
explicit initialisation, there is no functional change
in how timer 1 is programmed.
Tested on n2100, compile-tested for all plat-iop machines.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/arch/arm/plat-iop/time.c b/arch/arm/plat-iop/time.c
index 8da95d5..5506c9b 100644
--- a/arch/arm/plat-iop/time.c
+++ b/arch/arm/plat-iop/time.c
@@ -19,6 +19,7 @@
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/io.h>
+#include <linux/clocksource.h>
#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
@@ -26,6 +27,43 @@
#include <asm/mach/time.h>
#include <mach/time.h>
+/*
+ * IOP clocksource (free-running timer 1).
+ */
+static cycle_t iop_clocksource_read(struct clocksource *unused)
+{
+ return 0xffffffffu - read_tcr1();
+}
+
+static struct clocksource iop_clocksource = {
+ .name = "iop_timer1",
+ .rating = 300,
+ .read = iop_clocksource_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static void __init iop_clocksource_set_hz(struct clocksource *cs, unsigned int hz)
+{
+ u64 temp;
+ u32 shift;
+
+ /* Find shift and mult values for hz. */
+ shift = 32;
+ do {
+ temp = (u64) NSEC_PER_SEC << shift;
+ do_div(temp, hz);
+ if ((temp >> 32) == 0)
+ break;
+ } while (--shift != 0);
+
+ cs->shift = shift;
+ cs->mult = (u32) temp;
+
+ printk(KERN_INFO "clocksource: %s uses shift %u mult %#x\n",
+ cs->name, cs->shift, cs->mult);
+}
+
static unsigned long ticks_per_jiffy;
static unsigned long ticks_per_usec;
static unsigned long next_jiffy_time;
@@ -99,8 +137,15 @@
*/
write_trr0(ticks_per_jiffy - 1);
write_tmr0(timer_ctl);
+
+ /*
+ * Set up free-running clocksource timer 1.
+ */
write_trr1(0xffffffff);
+ write_tcr1(0xffffffff);
write_tmr1(timer_ctl);
+ iop_clocksource_set_hz(&iop_clocksource, tick_rate);
+ clocksource_register(&iop_clocksource);
setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq);
}