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

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Message-Id: <9c839d3258d855fab2ba73cece5d982e28a7ca6e.1542589838.git.fthain@telegraphics.com.au>
Date:   Mon, 19 Nov 2018 12:10:38 +1100
From:   Finn Thain <fthain@...egraphics.com.au>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Andreas Schwab <schwab@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Stephen N Chivers <schivers@....com.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michael Schmitz <schmitzmic@...il.com>,
        John Stultz <john.stultz@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v2 13/14] m68k: mvme16x: Convert to clocksource API

Add a platform clocksource by adapting the existing arch_gettimeoffset
implementation.

Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
Acked-by: Linus Walleij <linus.walleij@...aro.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