linux-kernel - [RFC PATCH 11/13] m68k: mac: Convert to clocksource API

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Date:   Mon, 12 Nov 2018 15:12:39 +1100
From:   Finn Thain <fthain@...egraphics.com.au>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Stephen N Chivers <schivers@....com.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
        Joshua Thompson <funaho@...ai.org>
Subject: [RFC PATCH 11/13] m68k: mac: Convert to clocksource API

Add a platform clocksource by adapting the existing arch_gettimeoffset
implementation.

Cc: Joshua Thompson <funaho@...ai.org>
Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
---
 arch/m68k/mac/via.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index 7130abec0b77..c4c304470fae 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>
@@ -556,13 +557,23 @@ 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;
 static bool lost_timer_intr;
 
 static irqreturn_t via_timer_handler(int irq, void *data)
@@ -573,16 +584,18 @@ static irqreturn_t via_timer_handler(int irq, void *data)
 	local_irq_save(flags);
 	if (lost_timer_intr) {
 		lost_timer_intr = false;
-		local_irq_restore(flags);
-		func(irq, data);
-	} else
-		local_irq_restore(flags);
+		clk_total += VIA_TIMER_CYCLES;
+	}
+	clk_total += VIA_TIMER_CYCLES;
+	local_irq_restore(flags);
+
 	return func(irq, data);
 }
 
 void __init via_init_clock(irq_handler_t func)
 {
-	if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, 0, "timer", func)) {
+	if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER,
+			"timer", func)) {
 		pr_err("Couldn't register %s interrupt\n", "timer");
 		return;
 	}
@@ -592,11 +605,13 @@ void __init via_init_clock(irq_handler_t func)
 	via1[vT1CL] = VIA_TC_LOW;
 	via1[vT1CH] = VIA_TC_HIGH;
 	via1[vACR] |= 0x40;
+
+	clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ);
 }
 
 #define VIA_T1_INT_FLAG BIT(6)
 
-u32 mac_gettimeoffset(void)
+static u64 mac_read_clk(struct clocksource *cs)
 {
 	unsigned long flags;
 	u8 count_high, count_high_new, count_low;
@@ -631,5 +646,5 @@ u32 mac_gettimeoffset(void)
 	count = ((count_high << 8) | count_low) + 1;
 	count = VIA_TIMER_CYCLES - count + offset;
 
-	return ((count * VIA_TIMER_INTERVAL) / VIA_TIMER_CYCLES) * 1000;
+	return clk_total + count;
 }
-- 
2.18.1