Add a platform clocksource by adapting the existing arch_gettimeoffset
implementation.
Signed-off-by: Finn Thain <fth...@telegraphics.com.au>
Acked-by: Linus Walleij <linus.wall...@linaro.org>
Tested-by: Stan Johnson <user...@yahoo.com>
---
Changed since v3:
- Use clk_offset variable to track the offset when the irq check is skipped.
Changed since v2:
- Drop 'clk_offset' variable.
Changed since v1:
- Moved clk_total access to within the irq lock.
- Use type u32 for tick counter.
---
arch/m68k/mac/via.c | 45 ++++++++++++++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 9 deletions(-)
diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index 65aca12a8694..31cccc79cb7a 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -23,6 +23,7 @@
*
*/
+#include <linux/clocksource.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
@@ -573,16 +574,39 @@ EXPORT_SYMBOL(via2_scsi_drq_pending);
/* timer and clock source */
#define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz
*/
-#define VIA_TIMER_INTERVAL (1000000 / HZ) /* microseconds per jiffy */
#define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
#define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
#define VIA_TC_LOW (VIA_TC & 0xFF)
#define VIA_TC_HIGH (VIA_TC >> 8)
+static u64 mac_read_clk(struct clocksource *cs);
+
+static struct clocksource mac_clk = {
+ .name = "via1",
+ .rating = 250,
+ .read = mac_read_clk,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static u32 clk_total, clk_offset;
+
+static irqreturn_t via_timer_handler(int irq, void *dev_id)
+{
+ irq_handler_t timer_routine = dev_id;
+
+ clk_total += VIA_TIMER_CYCLES;
+ clk_offset = 0;
+ timer_routine(0, NULL);
+
+ return IRQ_HANDLED;
+}
+
void __init via_init_clock(irq_handler_t timer_routine)
{
- if (request_irq(IRQ_MAC_TIMER_1, timer_routine, 0, "timer", NULL)) {
+ if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER, "timer",
+ timer_routine)) {
pr_err("Couldn't register %s interrupt\n", "timer");
return;
}
@@ -592,13 +616,16 @@ void __init via_init_clock(irq_handler_t timer_routine)
via1[vT1CL] = VIA_TC_LOW;
via1[vT1CH] = VIA_TC_HIGH;
via1[vACR] |= 0x40;
+
+ clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ);
}
-u32 mac_gettimeoffset(void)
+static u64 mac_read_clk(struct clocksource *cs)
{
unsigned long flags;
u8 count_high;
- u16 count, offset = 0;
+ u16 count;
+ u32 ticks;
/*
* Timer counter wrap-around is detected with the timer interrupt flag
@@ -614,11 +641,11 @@ u32 mac_gettimeoffset(void)
if (count_high == 0xFF)
count_high = 0;
if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
- offset = VIA_TIMER_CYCLES;
- local_irq_restore(flags);
-
+ clk_offset = VIA_TIMER_CYCLES;
count = count_high << 8;
- count = VIA_TIMER_CYCLES - count + offset;
+ ticks = VIA_TIMER_CYCLES - count;
+ ticks += clk_offset + clk_total;
+ local_irq_restore(flags);
- return ((count * VIA_TIMER_INTERVAL) / VIA_TIMER_CYCLES) * 1000;
+ return ticks;
}
--
2.18.1
