[RFC PATCH 08/13] m68k: atari: Convert to clocksource API

[Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>]

Add a platform clocksource by adapting the existing arch_gettimeoffset
implementation.

Cc: Michael Schmitz <schmitzmic@xxxxxxxxx>
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
---
 arch/m68k/atari/time.c | 39 ++++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/m68k/atari/time.c b/arch/m68k/atari/time.c
index 4765e9a58293..d066599fcc54 100644
--- a/arch/m68k/atari/time.c
+++ b/arch/m68k/atari/time.c
@@ -16,6 +16,7 @@
 #include <linux/init.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
+#include <linux/clocksource.h>
 #include <linux/delay.h>
 #include <linux/export.h>
 
@@ -24,6 +25,30 @@
 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL_GPL(rtc_lock);
 
+static u64 atari_read_clk(struct clocksource *cs);
+
+static struct clocksource atari_clk = {
+	.name   = "mfp",
+	.rating = 250,
+	.read   = atari_read_clk,
+	.mask   = CLOCKSOURCE_MASK(32),
+	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static u32 clk_total;
+
+static irqreturn_t mfp_timer_handler(int irq, void *data)
+{
+	irq_handler_t func = data;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	clk_total += INT_TICKS;
+	local_irq_restore(flags);
+
+	return func(irq, data);
+}
+
 void __init
 atari_sched_init(irq_handler_t timer_routine)
 {
@@ -32,15 +57,16 @@ atari_sched_init(irq_handler_t timer_routine)
     /* start timer C, div = 1:100 */
     st_mfp.tim_ct_cd = (st_mfp.tim_ct_cd & 15) | 0x60;
     /* install interrupt service routine for MFP Timer C */
-    if (request_irq(IRQ_MFP_TIMC, timer_routine, 0, "timer", timer_routine))
+    if (request_irq(IRQ_MFP_TIMC, mfp_timer_handler, IRQF_TIMER, "timer",
+                    timer_routine))
 	pr_err("Couldn't register timer interrupt\n");
+
+    clocksource_register_hz(&atari_clk, INT_CLK);
 }
 
 /* ++andreas: gettimeoffset fixed to check for pending interrupt */
 
-#define TICK_SIZE 10000
-
-u32 atari_gettimeoffset(void)
+static u64 atari_read_clk(struct clocksource *cs)
 {
   unsigned long flags;
   u32 ticks, offset = 0;
@@ -53,14 +79,13 @@ u32 atari_gettimeoffset(void)
   if (ticks > INT_TICKS - INT_TICKS / 50)
     /* Check for pending timer interrupt */
     if (st_mfp.int_pn_b & (1 << 5))
-      offset = TICK_SIZE;
+      offset = INT_TICKS;
 
   local_irq_restore(flags);
 
   ticks = INT_TICKS - ticks;
-  ticks = ticks * 10000L / INT_TICKS;
 
-  return (ticks + offset) * 1000;
+  return clk_total + ticks + offset;
 }
 
 
-- 
2.18.1