diff mbox

[1/2] timer: vt8500: Move system timer to clocksource

Message ID 1357183510-8476-2-git-send-email-linux@prisktech.co.nz (mailing list archive)
State New, archived
Headers show

Commit Message

Tony Prisk Jan. 3, 2013, 3:25 a.m. UTC
Move mach-vt8500/timer.c to drivers/clocksource/vt8500_timer.c
and make necessary changes to Kconfig and Makefile.

vt8500_timer is moved from vt8500.c to clocksource/vt8500_timer.c
and added to common.h for reference from the board descriptor.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
---
CC: John Stultz <johnstul@us.ibm.com>
CC: Thomas Gleixner <tglx@linutronix.de>

 arch/arm/mach-vt8500/Kconfig       |    1 +
 arch/arm/mach-vt8500/Makefile      |    2 +-
 arch/arm/mach-vt8500/common.h      |    5 +-
 arch/arm/mach-vt8500/timer.c       |  184 -----------------------------------
 arch/arm/mach-vt8500/vt8500.c      |    4 -
 drivers/clocksource/Kconfig        |    3 +
 drivers/clocksource/Makefile       |    1 +
 drivers/clocksource/vt8500_timer.c |  187 ++++++++++++++++++++++++++++++++++++
 8 files changed, 197 insertions(+), 190 deletions(-)
 delete mode 100644 arch/arm/mach-vt8500/timer.c
 create mode 100644 drivers/clocksource/vt8500_timer.c

Comments

Dmitry Torokhov Jan. 3, 2013, 7:35 a.m. UTC | #1
On Thu, Jan 03, 2013 at 04:25:09PM +1300, Tony Prisk wrote:
> +static void __init vt8500_timer_init(void)
> +{
> +	struct device_node *np;
> +	int timer_irq;
> +
> +	np = of_find_matching_node(NULL, vt8500_timer_ids);
> +	if (!np) {
> +		pr_err("%s: Timer description missing from Device Tree\n",
> +								__func__);
> +		return;
> +	}
> +	regbase = of_iomap(np, 0);
> +	if (!regbase) {
> +		pr_err("%s: Missing iobase description in Device Tree\n",
> +								__func__);
> +		of_node_put(np);
> +		return;
> +	}
> +	timer_irq = irq_of_parse_and_map(np, 0);
> +	if (!timer_irq) {
> +		pr_err("%s: Missing irq description in Device Tree\n",
> +								__func__);
> +		of_node_put(np);
> +		return;

You are forgetting to unmap the regbase here.

Thanks.
Joe Perches Jan. 3, 2013, 7:45 a.m. UTC | #2
On Wed, 2013-01-02 at 23:35 -0800, Dmitry Torokhov wrote:
> On Thu, Jan 03, 2013 at 04:25:09PM +1300, Tony Prisk wrote:
> > +static void __init vt8500_timer_init(void)
> > +{
> > +	struct device_node *np;
> > +	int timer_irq;
> > +
> > +	np = of_find_matching_node(NULL, vt8500_timer_ids);
> > +	if (!np) {
> > +		pr_err("%s: Timer description missing from Device Tree\n",
> > +								__func__);
> > +		return;
> > +	}
> > +	regbase = of_iomap(np, 0);
> > +	if (!regbase) {
> > +		pr_err("%s: Missing iobase description in Device Tree\n",
> > +								__func__);
> > +		of_node_put(np);
> > +		return;
> > +	}
> > +	timer_irq = irq_of_parse_and_map(np, 0);
> > +	if (!timer_irq) {
> > +		pr_err("%s: Missing irq description in Device Tree\n",
> > +								__func__);
> > +		of_node_put(np);
> > +		return;
> 
> You are forgetting to unmap the regbase here.

Also I think it'd be nicer to write something like:

	struct device_node *np;
	int timer_irq;
	const char *reason;

	np = of_find_matching_node(NULL, vt8500_timer_ids);
	if (!np) {
		reason = "timer";
	    goto error;
	}
	regbase = of_iomap(np, 0);
	if (!regbase) {
		reason = "iobase";
		goto error_put;
	}
	timer_irq = irq_of_parse_and_map(np, 0);
	if (!timer_irq) {
		reason = "irq";
		goto error_remap;
	}
 
	...

error_remap:
	unmap...;
error_put:
	of_node_put(np);
error:
	pr_err("%s: Missing %s description in Device Tree\n",
	       __func__, reason);
	return;
Arnd Bergmann Jan. 3, 2013, 8:07 a.m. UTC | #3
On Thursday 03 January 2013, Joe Perches wrote:
> Also I think it'd be nicer to write something like:
> 
>         struct device_node *np;
>         int timer_irq;
>         const char *reason;
> 
>         np = of_find_matching_node(NULL, vt8500_timer_ids);
>         if (!np) {
>                 reason = "timer";
>             goto error;
>         }
>         regbase = of_iomap(np, 0);
>         if (!regbase) {
>                 reason = "iobase";
>                 goto error_put;
>         }
>         timer_irq = irq_of_parse_and_map(np, 0);
>         if (!timer_irq) {
>                 reason = "irq";
>                 goto error_remap;
>         }
>  
>         ...
> 
> error_remap:
>         unmap...;
> error_put:
>         of_node_put(np);
> error:
>         pr_err("%s: Missing %s description in Device Tree\n",
>                __func__, reason);
>         return;

Right, but that would be a separate cleanup patch, since the patch that
Tony posted is just supposed to move the code around and change as little
else as possible in the process. The cleanup can come either right before
or right after the move.

	Arnd
Stephen Warren Jan. 3, 2013, 5:29 p.m. UTC | #4
On 01/02/2013 08:25 PM, Tony Prisk wrote:
> Move mach-vt8500/timer.c to drivers/clocksource/vt8500_timer.c
> and make necessary changes to Kconfig and Makefile.
> 
> vt8500_timer is moved from vt8500.c to clocksource/vt8500_timer.c
> and added to common.h for reference from the board descriptor.

> diff --git a/arch/arm/mach-vt8500/common.h b/arch/arm/mach-vt8500/common.h

> +/* defined in drivers/clocksource/vt8500_timer.c */
> +extern struct sys_timer vt8500_timer;
> +void __init vt8500_timer_init(void);

struct sys_timer has been deleted; the patches to do so are in the most
recent 2 linux-next. Another advantage of this change if your SoC
supports DT is that you don't need to explicitly prototype a separate
struct or function per clocksource driver, but board files can simply
call clocksource_of_init(), and the core code will look up the
appropriate clocksource driver to initialize using DT.

You can find the series at:

git://git.kernel.org/pub/scm/linux/kernel/git/swarren/linux-tegra.git
arm-timer-rework

I believe that branch should be stable now unless any bugs are found so
you can base your changes on it; I plan to send a pull request to
include that branch in arm-soc tomorrow morning.
diff mbox

Patch

diff --git a/arch/arm/mach-vt8500/Kconfig b/arch/arm/mach-vt8500/Kconfig
index 2ed0b7d..570a801 100644
--- a/arch/arm/mach-vt8500/Kconfig
+++ b/arch/arm/mach-vt8500/Kconfig
@@ -8,5 +8,6 @@  config ARCH_VT8500
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_GPIO
 	select HAVE_CLK
+	select VT8500_TIMER
 	help
 	  Support for VIA/WonderMedia VT8500/WM85xx System-on-Chip.
diff --git a/arch/arm/mach-vt8500/Makefile b/arch/arm/mach-vt8500/Makefile
index e035251..92ceb24 100644
--- a/arch/arm/mach-vt8500/Makefile
+++ b/arch/arm/mach-vt8500/Makefile
@@ -1 +1 @@ 
-obj-$(CONFIG_ARCH_VT8500) += irq.o timer.o vt8500.o
+obj-$(CONFIG_ARCH_VT8500) += irq.o vt8500.o
diff --git a/arch/arm/mach-vt8500/common.h b/arch/arm/mach-vt8500/common.h
index 6f2b843..5d37a4f 100644
--- a/arch/arm/mach-vt8500/common.h
+++ b/arch/arm/mach-vt8500/common.h
@@ -18,7 +18,6 @@ 
 
 #include <linux/of.h>
 
-void __init vt8500_timer_init(void);
 int __init vt8500_irq_init(struct device_node *node,
 				struct device_node *parent);
 
@@ -28,4 +27,8 @@  void __init vtwm_clk_init(void __iomem *pmc_base);
 /* defined in irq.c */
 asmlinkage void vt8500_handle_irq(struct pt_regs *regs);
 
+/* defined in drivers/clocksource/vt8500_timer.c */
+extern struct sys_timer vt8500_timer;
+void __init vt8500_timer_init(void);
+
 #endif
diff --git a/arch/arm/mach-vt8500/timer.c b/arch/arm/mach-vt8500/timer.c
deleted file mode 100644
index 3dd21a4..0000000
--- a/arch/arm/mach-vt8500/timer.c
+++ /dev/null
@@ -1,184 +0,0 @@ 
-/*
- *  arch/arm/mach-vt8500/timer.c
- *
- *  Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
- *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- */
-
-/*
- * This file is copied and modified from the original timer.c provided by
- * Alexey Charkov. Minor changes have been made for Device Tree Support.
- */
-
-#include <linux/io.h>
-#include <linux/irq.h>
-#include <linux/interrupt.h>
-#include <linux/clocksource.h>
-#include <linux/clockchips.h>
-#include <linux/delay.h>
-#include <asm/mach/time.h>
-
-#include <linux/of.h>
-#include <linux/of_address.h>
-#include <linux/of_irq.h>
-
-#define VT8500_TIMER_OFFSET	0x0100
-#define VT8500_TIMER_HZ		3000000
-#define TIMER_MATCH_VAL		0x0000
-#define TIMER_COUNT_VAL		0x0010
-#define TIMER_STATUS_VAL	0x0014
-#define TIMER_IER_VAL		0x001c		/* interrupt enable */
-#define TIMER_CTRL_VAL		0x0020
-#define TIMER_AS_VAL		0x0024		/* access status */
-#define TIMER_COUNT_R_ACTIVE	(1 << 5)	/* not ready for read */
-#define TIMER_COUNT_W_ACTIVE	(1 << 4)	/* not ready for write */
-#define TIMER_MATCH_W_ACTIVE	(1 << 0)	/* not ready for write */
-
-#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
-
-static void __iomem *regbase;
-
-static cycle_t vt8500_timer_read(struct clocksource *cs)
-{
-	int loops = msecs_to_loops(10);
-	writel(3, regbase + TIMER_CTRL_VAL);
-	while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
-						&& --loops)
-		cpu_relax();
-	return readl(regbase + TIMER_COUNT_VAL);
-}
-
-static struct clocksource clocksource = {
-	.name           = "vt8500_timer",
-	.rating         = 200,
-	.read           = vt8500_timer_read,
-	.mask           = CLOCKSOURCE_MASK(32),
-	.flags          = CLOCK_SOURCE_IS_CONTINUOUS,
-};
-
-static int vt8500_timer_set_next_event(unsigned long cycles,
-				    struct clock_event_device *evt)
-{
-	int loops = msecs_to_loops(10);
-	cycle_t alarm = clocksource.read(&clocksource) + cycles;
-	while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
-						&& --loops)
-		cpu_relax();
-	writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
-
-	if ((signed)(alarm - clocksource.read(&clocksource)) <= 16)
-		return -ETIME;
-
-	writel(1, regbase + TIMER_IER_VAL);
-
-	return 0;
-}
-
-static void vt8500_timer_set_mode(enum clock_event_mode mode,
-			      struct clock_event_device *evt)
-{
-	switch (mode) {
-	case CLOCK_EVT_MODE_RESUME:
-	case CLOCK_EVT_MODE_PERIODIC:
-		break;
-	case CLOCK_EVT_MODE_ONESHOT:
-	case CLOCK_EVT_MODE_UNUSED:
-	case CLOCK_EVT_MODE_SHUTDOWN:
-		writel(readl(regbase + TIMER_CTRL_VAL) | 1,
-			regbase + TIMER_CTRL_VAL);
-		writel(0, regbase + TIMER_IER_VAL);
-		break;
-	}
-}
-
-static struct clock_event_device clockevent = {
-	.name           = "vt8500_timer",
-	.features       = CLOCK_EVT_FEAT_ONESHOT,
-	.rating         = 200,
-	.set_next_event = vt8500_timer_set_next_event,
-	.set_mode       = vt8500_timer_set_mode,
-};
-
-static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
-{
-	struct clock_event_device *evt = dev_id;
-	writel(0xf, regbase + TIMER_STATUS_VAL);
-	evt->event_handler(evt);
-
-	return IRQ_HANDLED;
-}
-
-static struct irqaction irq = {
-	.name    = "vt8500_timer",
-	.flags   = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
-	.handler = vt8500_timer_interrupt,
-	.dev_id  = &clockevent,
-};
-
-static struct of_device_id vt8500_timer_ids[] = {
-	{ .compatible = "via,vt8500-timer" },
-	{ }
-};
-
-void __init vt8500_timer_init(void)
-{
-	struct device_node *np;
-	int timer_irq;
-
-	np = of_find_matching_node(NULL, vt8500_timer_ids);
-	if (!np) {
-		pr_err("%s: Timer description missing from Device Tree\n",
-								__func__);
-		return;
-	}
-	regbase = of_iomap(np, 0);
-	if (!regbase) {
-		pr_err("%s: Missing iobase description in Device Tree\n",
-								__func__);
-		of_node_put(np);
-		return;
-	}
-	timer_irq = irq_of_parse_and_map(np, 0);
-	if (!timer_irq) {
-		pr_err("%s: Missing irq description in Device Tree\n",
-								__func__);
-		of_node_put(np);
-		return;
-	}
-
-	writel(1, regbase + TIMER_CTRL_VAL);
-	writel(0xf, regbase + TIMER_STATUS_VAL);
-	writel(~0, regbase + TIMER_MATCH_VAL);
-
-	if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
-		pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n",
-					__func__, clocksource.name);
-
-	clockevents_calc_mult_shift(&clockevent, VT8500_TIMER_HZ, 4);
-
-	/* copy-pasted from mach-msm; no idea */
-	clockevent.max_delta_ns =
-		clockevent_delta2ns(0xf0000000, &clockevent);
-	clockevent.min_delta_ns = clockevent_delta2ns(4, &clockevent);
-	clockevent.cpumask = cpumask_of(0);
-
-	if (setup_irq(timer_irq, &irq))
-		pr_err("%s: setup_irq failed for %s\n", __func__,
-							clockevent.name);
-	clockevents_register_device(&clockevent);
-}
-
diff --git a/arch/arm/mach-vt8500/vt8500.c b/arch/arm/mach-vt8500/vt8500.c
index 3c66d48..ed1c02b 100644
--- a/arch/arm/mach-vt8500/vt8500.c
+++ b/arch/arm/mach-vt8500/vt8500.c
@@ -175,10 +175,6 @@  static void __init vt8500_init_irq(void)
 	of_irq_init(vt8500_irq_match);
 };
 
-static struct sys_timer vt8500_timer = {
-	.init = vt8500_timer_init,
-};
-
 static const char * const vt8500_dt_compat[] = {
 	"via,vt8500",
 	"wm,wm8650",
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 7fdcbd3..67883ce 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -25,6 +25,9 @@  config ARMADA_370_XP_TIMER
 config SUNXI_TIMER
 	bool
 
+config VT8500_TIMER
+	bool
+
 config CLKSRC_NOMADIK_MTU
 	bool
 	depends on (ARCH_NOMADIK || ARCH_U8500)
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index f93453d..c778d01 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -16,5 +16,6 @@  obj-$(CONFIG_CLKSRC_DBX500_PRCMU)	+= clksrc-dbx500-prcmu.o
 obj-$(CONFIG_ARMADA_370_XP_TIMER)	+= time-armada-370-xp.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
 obj-$(CONFIG_SUNXI_TIMER)	+= sunxi_timer.o
+obj-$(CONFIG_VT8500_TIMER)	+= vt8500_timer.o
 
 obj-$(CONFIG_CLKSRC_ARM_GENERIC)	+= arm_generic.o
diff --git a/drivers/clocksource/vt8500_timer.c b/drivers/clocksource/vt8500_timer.c
new file mode 100644
index 0000000..acb565a
--- /dev/null
+++ b/drivers/clocksource/vt8500_timer.c
@@ -0,0 +1,187 @@ 
+/*
+ *  arch/arm/mach-vt8500/timer.c
+ *
+ *  Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
+ *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/*
+ * This file is copied and modified from the original timer.c provided by
+ * Alexey Charkov. Minor changes have been made for Device Tree Support.
+ */
+
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+#include <asm/mach/time.h>
+
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define VT8500_TIMER_OFFSET	0x0100
+#define VT8500_TIMER_HZ		3000000
+#define TIMER_MATCH_VAL		0x0000
+#define TIMER_COUNT_VAL		0x0010
+#define TIMER_STATUS_VAL	0x0014
+#define TIMER_IER_VAL		0x001c		/* interrupt enable */
+#define TIMER_CTRL_VAL		0x0020
+#define TIMER_AS_VAL		0x0024		/* access status */
+#define TIMER_COUNT_R_ACTIVE	(1 << 5)	/* not ready for read */
+#define TIMER_COUNT_W_ACTIVE	(1 << 4)	/* not ready for write */
+#define TIMER_MATCH_W_ACTIVE	(1 << 0)	/* not ready for write */
+
+#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
+
+static void __iomem *regbase;
+
+static cycle_t vt8500_timer_read(struct clocksource *cs)
+{
+	int loops = msecs_to_loops(10);
+	writel(3, regbase + TIMER_CTRL_VAL);
+	while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)
+						&& --loops)
+		cpu_relax();
+	return readl(regbase + TIMER_COUNT_VAL);
+}
+
+static struct clocksource clocksource = {
+	.name           = "vt8500_timer",
+	.rating         = 200,
+	.read           = vt8500_timer_read,
+	.mask           = CLOCKSOURCE_MASK(32),
+	.flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int vt8500_timer_set_next_event(unsigned long cycles,
+				    struct clock_event_device *evt)
+{
+	int loops = msecs_to_loops(10);
+	cycle_t alarm = clocksource.read(&clocksource) + cycles;
+	while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)
+						&& --loops)
+		cpu_relax();
+	writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);
+
+	if ((signed)(alarm - clocksource.read(&clocksource)) <= 16)
+		return -ETIME;
+
+	writel(1, regbase + TIMER_IER_VAL);
+
+	return 0;
+}
+
+static void vt8500_timer_set_mode(enum clock_event_mode mode,
+			      struct clock_event_device *evt)
+{
+	switch (mode) {
+	case CLOCK_EVT_MODE_RESUME:
+	case CLOCK_EVT_MODE_PERIODIC:
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		writel(readl(regbase + TIMER_CTRL_VAL) | 1,
+			regbase + TIMER_CTRL_VAL);
+		writel(0, regbase + TIMER_IER_VAL);
+		break;
+	}
+}
+
+static struct clock_event_device clockevent = {
+	.name           = "vt8500_timer",
+	.features       = CLOCK_EVT_FEAT_ONESHOT,
+	.rating         = 200,
+	.set_next_event = vt8500_timer_set_next_event,
+	.set_mode       = vt8500_timer_set_mode,
+};
+
+static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+	writel(0xf, regbase + TIMER_STATUS_VAL);
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction irq = {
+	.name    = "vt8500_timer",
+	.flags   = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+	.handler = vt8500_timer_interrupt,
+	.dev_id  = &clockevent,
+};
+
+static struct of_device_id vt8500_timer_ids[] = {
+	{ .compatible = "via,vt8500-timer" },
+	{ }
+};
+
+static void __init vt8500_timer_init(void)
+{
+	struct device_node *np;
+	int timer_irq;
+
+	np = of_find_matching_node(NULL, vt8500_timer_ids);
+	if (!np) {
+		pr_err("%s: Timer description missing from Device Tree\n",
+								__func__);
+		return;
+	}
+	regbase = of_iomap(np, 0);
+	if (!regbase) {
+		pr_err("%s: Missing iobase description in Device Tree\n",
+								__func__);
+		of_node_put(np);
+		return;
+	}
+	timer_irq = irq_of_parse_and_map(np, 0);
+	if (!timer_irq) {
+		pr_err("%s: Missing irq description in Device Tree\n",
+								__func__);
+		of_node_put(np);
+		return;
+	}
+
+	writel(1, regbase + TIMER_CTRL_VAL);
+	writel(0xf, regbase + TIMER_STATUS_VAL);
+	writel(~0, regbase + TIMER_MATCH_VAL);
+
+	if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ))
+		pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n",
+					__func__, clocksource.name);
+
+	clockevents_calc_mult_shift(&clockevent, VT8500_TIMER_HZ, 4);
+
+	/* copy-pasted from mach-msm; no idea */
+	clockevent.max_delta_ns =
+		clockevent_delta2ns(0xf0000000, &clockevent);
+	clockevent.min_delta_ns = clockevent_delta2ns(4, &clockevent);
+	clockevent.cpumask = cpumask_of(0);
+
+	if (setup_irq(timer_irq, &irq))
+		pr_err("%s: setup_irq failed for %s\n", __func__,
+							clockevent.name);
+	clockevents_register_device(&clockevent);
+}
+
+struct sys_timer vt8500_timer = {
+	.init = vt8500_timer_init,
+};