[RFC PATCH v2 13/14] m68k: mvme16x: Convert to clocksource API

[Finn Thain]

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>
---
Changed since v1:
 - Moved clk_total access to within the irq lock.
---
 arch/m68k/mvme16x/config.c | 39 +++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/m68k/mvme16x/config.c b/arch/m68k/mvme16x/config.c
index 8bafa6a37593..2c109ee2a1a5 100644
--- a/arch/m68k/mvme16x/config.c
+++ b/arch/m68k/mvme16x/config.c
@@ -19,6 +19,7 @@
 #include <linux/mm.h>
 #include <linux/seq_file.h>
 #include <linux/tty.h>
+#include <linux/clocksource.h>
 #include <linux/console.h>
 #include <linux/linkage.h>
 #include <linux/init.h>
@@ -343,6 +344,21 @@ static irqreturn_t mvme16x_abort_int (int irq, void 
*dev_id)
        return IRQ_HANDLED;
 }
 
+static u64 mvme16x_read_clk(struct clocksource *cs);
+
+static struct clocksource mvme16x_clk = {
+       .name   = "pcc",
+       .rating = 250,
+       .read   = mvme16x_read_clk,
+       .mask   = CLOCKSOURCE_MASK(32),
+       .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static u32 clk_total;
+
+#define PCC_TIMER_CLOCK_FREQ 1000000
+#define PCC_TIMER_CYCLES     (PCC_TIMER_CLOCK_FREQ / HZ)
+
 static irqreturn_t mvme16x_timer_int (int irq, void *dev_id)
 {
        irq_handler_t timer_routine = dev_id;
@@ -350,6 +366,7 @@ static irqreturn_t mvme16x_timer_int (int irq, void *dev_id)
 
        local_irq_save(flags);
        *(volatile unsigned char *)0xfff4201b |= 8;
+       clk_total += PCC_TIMER_CYCLES;
        timer_routine(0, NULL);
        local_irq_restore(flags);
 
@@ -363,13 +380,15 @@ void mvme16x_sched_init (irq_handler_t timer_routine)
 
     /* Using PCCchip2 or MC2 chip tick timer 1 */
     *(volatile unsigned long *)0xfff42008 = 0;
-    *(volatile unsigned long *)0xfff42004 = 10000;     /* 10ms */
+    *(volatile unsigned long *)0xfff42004 = PCC_TIMER_CYCLES;
     *(volatile unsigned char *)0xfff42017 |= 3;
     *(volatile unsigned char *)0xfff4201b = 0x16;
-    if (request_irq(MVME16x_IRQ_TIMER, mvme16x_timer_int, 0,
-                    "timer", timer_routine))
+    if (request_irq(MVME16x_IRQ_TIMER, mvme16x_timer_int, IRQF_TIMER, "timer",
+                    timer_routine))
        panic ("Couldn't register timer int");
 
+    clocksource_register_hz(&mvme16x_clk, PCC_TIMER_CLOCK_FREQ);
+
     if (brdno == 0x0162 || brdno == 0x172)
        irq = MVME162_IRQ_ABORT;
     else
@@ -379,11 +398,17 @@ void mvme16x_sched_init (irq_handler_t timer_routine)
        panic ("Couldn't register abort int");
 }
 
-
-/* This is always executed with interrupts disabled.  */
-u32 mvme16x_gettimeoffset(void)
+static u64 mvme16x_read_clk(struct clocksource *cs)
 {
-    return (*(volatile u32 *)0xfff42008) * 1000;
+       unsigned long flags;
+       u32 ticks;
+
+       local_irq_save(flags);
+       ticks = *(volatile u32 *)0xfff42008;
+       ticks += clk_total;
+       local_irq_restore(flags);
+
+       return ticks;
 }
 
 int bcd2int (unsigned char b)
-- 
2.18.1