[RFC PATCH v3 11/14] m68k: mvme147: 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.
 - Use type u32 for tick counter.
---
 arch/m68k/include/asm/mvme147hw.h |  1 -
 arch/m68k/mvme147/config.c        | 36 +++++++++++++++++++++++++------
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/arch/m68k/include/asm/mvme147hw.h 
b/arch/m68k/include/asm/mvme147hw.h
index 9c7ff67c5ffd..7c3dd513128e 100644
--- a/arch/m68k/include/asm/mvme147hw.h
+++ b/arch/m68k/include/asm/mvme147hw.h
@@ -66,7 +66,6 @@ struct pcc_regs {
 #define PCC_INT_ENAB           0x08
 
 #define PCC_TIMER_INT_CLR      0x80
-#define PCC_TIMER_PRELOAD      63936l
 
 #define PCC_LEVEL_ABORT                0x07
 #define PCC_LEVEL_SERIAL       0x04
diff --git a/arch/m68k/mvme147/config.c b/arch/m68k/mvme147/config.c
index 4ef4faa5ed8b..c44a254e8a8c 100644
--- a/arch/m68k/mvme147/config.c
+++ b/arch/m68k/mvme147/config.c
@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/tty.h>
+#include <linux/clocksource.h>
 #include <linux/console.h>
 #include <linux/linkage.h>
 #include <linux/init.h>
@@ -92,6 +93,21 @@ void __init config_mvme147(void)
                vme_brdtype = VME_TYPE_MVME147;
 }
 
+static u64 mvme147_read_clk(struct clocksource *cs);
+
+static struct clocksource mvme147_clk = {
+       .name   = "pcc",
+       .rating = 250,
+       .read   = mvme147_read_clk,
+       .mask   = CLOCKSOURCE_MASK(32),
+       .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static u32 clk_total;
+
+#define PCC_TIMER_CLOCK_FREQ 160000
+#define PCC_TIMER_CYCLES     (PCC_TIMER_CLOCK_FREQ / HZ)
+#define PCC_TIMER_PRELOAD    (0x10000 - PCC_TIMER_CYCLES)
 
 /* Using pcc tick timer 1 */
 
@@ -103,6 +119,7 @@ static irqreturn_t mvme147_timer_int (int irq, void *dev_id)
        local_irq_save(flags);
        m147_pcc->t1_int_cntrl = PCC_TIMER_INT_CLR;
        m147_pcc->t1_int_cntrl = PCC_INT_ENAB|PCC_LEVEL_TIMER1;
+       clk_total += PCC_TIMER_CYCLES;
        timer_routine(0, NULL);
        local_irq_restore(flags);
 
@@ -112,32 +129,39 @@ static irqreturn_t mvme147_timer_int (int irq, void 
*dev_id)
 
 void mvme147_sched_init (irq_handler_t timer_routine)
 {
-       if (request_irq(PCC_IRQ_TIMER1, mvme147_timer_int, 0, "timer 1",
-                       timer_routine))
+       if (request_irq(PCC_IRQ_TIMER1, mvme147_timer_int, IRQF_TIMER,
+                       "timer 1", timer_routine))
                pr_err("Couldn't register timer interrupt\n");
 
        /* Init the clock with a value */
-       /* our clock goes off every 6.25us */
+       /* The clock counter increments until 0xFFFF then reloads */
        m147_pcc->t1_preload = PCC_TIMER_PRELOAD;
        m147_pcc->t1_cntrl = 0x0;       /* clear timer */
        m147_pcc->t1_cntrl = 0x3;       /* start timer */
        m147_pcc->t1_int_cntrl = PCC_TIMER_INT_CLR;  /* clear pending ints */
        m147_pcc->t1_int_cntrl = PCC_INT_ENAB|PCC_LEVEL_TIMER1;
+
+       clocksource_register_hz(&mvme147_clk, PCC_TIMER_CLOCK_FREQ);
 }
 
-/* This is always executed with interrupts disabled.  */
 /* XXX There are race hazards in this code XXX */
-u32 mvme147_gettimeoffset(void)
+static u64 mvme147_read_clk(struct clocksource *cs)
 {
+       unsigned long flags;
        volatile unsigned short *cp = (volatile unsigned short *)0xfffe1012;
        unsigned short n;
+       u32 ticks;
 
+       local_irq_save(flags);
        n = *cp;
        while (n != *cp)
                n = *cp;
 
        n -= PCC_TIMER_PRELOAD;
-       return ((unsigned long)n * 25 / 4) * 1000;
+       ticks = clk_total + n;
+       local_irq_restore(flags);
+
+       return ticks;
 }
 
 static int bcd2int (unsigned char b)
-- 
2.18.1