ARM: u300: move timer driver to clocksource

Move the U300 timer driver down to the clocksource driver
subsystem and keep arch/arm clean.

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

2 files changed, 448 insertions, 0 deletions

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index c7ca50a9c232..01e5435315ca 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_ARCH_MARCO)	+= timer-marco.o
 obj-$(CONFIG_ARCH_MOXART)	+= moxart_timer.o
 obj-$(CONFIG_ARCH_MXS)		+= mxs_timer.o
 obj-$(CONFIG_ARCH_PRIMA2)	+= timer-prima2.o
+obj-$(CONFIG_ARCH_U300)		+= timer-u300.o
 obj-$(CONFIG_SUN4I_TIMER)	+= sun4i_timer.o
 obj-$(CONFIG_SUN5I_HSTIMER)	+= timer-sun5i.o
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o
diff --git a/drivers/clocksource/timer-u300.c b/drivers/clocksource/timer-u300.c
new file mode 100644
index 000000000000..e63d469661fd
--- /dev/null
+++ b/drivers/clocksource/timer-u300.c
@@ -0,0 +1,447 @@
+/*
+ * Copyright (C) 2007-2009 ST-Ericsson AB
+ * License terms: GNU General Public License (GPL) version 2
+ * Timer COH 901 328, runs the OS timer interrupt.
+ * Author: Linus Walleij <linus.walleij@stericsson.com>
+ */
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/timex.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/types.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/irq.h>
+#include <linux/delay.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+
+/* Generic stuff */
+#include <asm/mach/map.h>
+#include <asm/mach/time.h>
+
+/*
+ * APP side special timer registers
+ * This timer contains four timers which can fire an interrupt each.
+ * OS (operating system) timer @ 32768 Hz
+ * DD (device driver) timer @ 1 kHz
+ * GP1 (general purpose 1) timer @ 1MHz
+ * GP2 (general purpose 2) timer @ 1MHz
+ */
+
+/* Reset OS Timer 32bit (-/W) */
+#define U300_TIMER_APP_ROST					(0x0000)
+#define U300_TIMER_APP_ROST_TIMER_RESET				(0x00000000)
+/* Enable OS Timer 32bit (-/W) */
+#define U300_TIMER_APP_EOST					(0x0004)
+#define U300_TIMER_APP_EOST_TIMER_ENABLE			(0x00000000)
+/* Disable OS Timer 32bit (-/W) */
+#define U300_TIMER_APP_DOST					(0x0008)
+#define U300_TIMER_APP_DOST_TIMER_DISABLE			(0x00000000)
+/* OS Timer Mode Register 32bit (-/W) */
+#define U300_TIMER_APP_SOSTM					(0x000c)
+#define U300_TIMER_APP_SOSTM_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_SOSTM_MODE_ONE_SHOT			(0x00000001)
+/* OS Timer Status Register 32bit (R/-) */
+#define U300_TIMER_APP_OSTS					(0x0010)
+#define U300_TIMER_APP_OSTS_TIMER_STATE_MASK			(0x0000000F)
+#define U300_TIMER_APP_OSTS_TIMER_STATE_IDLE			(0x00000001)
+#define U300_TIMER_APP_OSTS_TIMER_STATE_ACTIVE			(0x00000002)
+#define U300_TIMER_APP_OSTS_ENABLE_IND				(0x00000010)
+#define U300_TIMER_APP_OSTS_MODE_MASK				(0x00000020)
+#define U300_TIMER_APP_OSTS_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_OSTS_MODE_ONE_SHOT			(0x00000020)
+#define U300_TIMER_APP_OSTS_IRQ_ENABLED_IND			(0x00000040)
+#define U300_TIMER_APP_OSTS_IRQ_PENDING_IND			(0x00000080)
+/* OS Timer Current Count Register 32bit (R/-) */
+#define U300_TIMER_APP_OSTCC					(0x0014)
+/* OS Timer Terminal Count Register 32bit (R/W) */
+#define U300_TIMER_APP_OSTTC					(0x0018)
+/* OS Timer Interrupt Enable Register 32bit (-/W) */
+#define U300_TIMER_APP_OSTIE					(0x001c)
+#define U300_TIMER_APP_OSTIE_IRQ_DISABLE			(0x00000000)
+#define U300_TIMER_APP_OSTIE_IRQ_ENABLE				(0x00000001)
+/* OS Timer Interrupt Acknowledge Register 32bit (-/W) */
+#define U300_TIMER_APP_OSTIA					(0x0020)
+#define U300_TIMER_APP_OSTIA_IRQ_ACK				(0x00000080)
+
+/* Reset DD Timer 32bit (-/W) */
+#define U300_TIMER_APP_RDDT					(0x0040)
+#define U300_TIMER_APP_RDDT_TIMER_RESET				(0x00000000)
+/* Enable DD Timer 32bit (-/W) */
+#define U300_TIMER_APP_EDDT					(0x0044)
+#define U300_TIMER_APP_EDDT_TIMER_ENABLE			(0x00000000)
+/* Disable DD Timer 32bit (-/W) */
+#define U300_TIMER_APP_DDDT					(0x0048)
+#define U300_TIMER_APP_DDDT_TIMER_DISABLE			(0x00000000)
+/* DD Timer Mode Register 32bit (-/W) */
+#define U300_TIMER_APP_SDDTM					(0x004c)
+#define U300_TIMER_APP_SDDTM_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_SDDTM_MODE_ONE_SHOT			(0x00000001)
+/* DD Timer Status Register 32bit (R/-) */
+#define U300_TIMER_APP_DDTS					(0x0050)
+#define U300_TIMER_APP_DDTS_TIMER_STATE_MASK			(0x0000000F)
+#define U300_TIMER_APP_DDTS_TIMER_STATE_IDLE			(0x00000001)
+#define U300_TIMER_APP_DDTS_TIMER_STATE_ACTIVE			(0x00000002)
+#define U300_TIMER_APP_DDTS_ENABLE_IND				(0x00000010)
+#define U300_TIMER_APP_DDTS_MODE_MASK				(0x00000020)
+#define U300_TIMER_APP_DDTS_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_DDTS_MODE_ONE_SHOT			(0x00000020)
+#define U300_TIMER_APP_DDTS_IRQ_ENABLED_IND			(0x00000040)
+#define U300_TIMER_APP_DDTS_IRQ_PENDING_IND			(0x00000080)
+/* DD Timer Current Count Register 32bit (R/-) */
+#define U300_TIMER_APP_DDTCC					(0x0054)
+/* DD Timer Terminal Count Register 32bit (R/W) */
+#define U300_TIMER_APP_DDTTC					(0x0058)
+/* DD Timer Interrupt Enable Register 32bit (-/W) */
+#define U300_TIMER_APP_DDTIE					(0x005c)
+#define U300_TIMER_APP_DDTIE_IRQ_DISABLE			(0x00000000)
+#define U300_TIMER_APP_DDTIE_IRQ_ENABLE				(0x00000001)
+/* DD Timer Interrupt Acknowledge Register 32bit (-/W) */
+#define U300_TIMER_APP_DDTIA					(0x0060)
+#define U300_TIMER_APP_DDTIA_IRQ_ACK				(0x00000080)
+
+/* Reset GP1 Timer 32bit (-/W) */
+#define U300_TIMER_APP_RGPT1					(0x0080)
+#define U300_TIMER_APP_RGPT1_TIMER_RESET			(0x00000000)
+/* Enable GP1 Timer 32bit (-/W) */
+#define U300_TIMER_APP_EGPT1					(0x0084)
+#define U300_TIMER_APP_EGPT1_TIMER_ENABLE			(0x00000000)
+/* Disable GP1 Timer 32bit (-/W) */
+#define U300_TIMER_APP_DGPT1					(0x0088)
+#define U300_TIMER_APP_DGPT1_TIMER_DISABLE			(0x00000000)
+/* GP1 Timer Mode Register 32bit (-/W) */
+#define U300_TIMER_APP_SGPT1M					(0x008c)
+#define U300_TIMER_APP_SGPT1M_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT			(0x00000001)
+/* GP1 Timer Status Register 32bit (R/-) */
+#define U300_TIMER_APP_GPT1S					(0x0090)
+#define U300_TIMER_APP_GPT1S_TIMER_STATE_MASK			(0x0000000F)
+#define U300_TIMER_APP_GPT1S_TIMER_STATE_IDLE			(0x00000001)
+#define U300_TIMER_APP_GPT1S_TIMER_STATE_ACTIVE			(0x00000002)
+#define U300_TIMER_APP_GPT1S_ENABLE_IND				(0x00000010)
+#define U300_TIMER_APP_GPT1S_MODE_MASK				(0x00000020)
+#define U300_TIMER_APP_GPT1S_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_GPT1S_MODE_ONE_SHOT			(0x00000020)
+#define U300_TIMER_APP_GPT1S_IRQ_ENABLED_IND			(0x00000040)
+#define U300_TIMER_APP_GPT1S_IRQ_PENDING_IND			(0x00000080)
+/* GP1 Timer Current Count Register 32bit (R/-) */
+#define U300_TIMER_APP_GPT1CC					(0x0094)
+/* GP1 Timer Terminal Count Register 32bit (R/W) */
+#define U300_TIMER_APP_GPT1TC					(0x0098)
+/* GP1 Timer Interrupt Enable Register 32bit (-/W) */
+#define U300_TIMER_APP_GPT1IE					(0x009c)
+#define U300_TIMER_APP_GPT1IE_IRQ_DISABLE			(0x00000000)
+#define U300_TIMER_APP_GPT1IE_IRQ_ENABLE			(0x00000001)
+/* GP1 Timer Interrupt Acknowledge Register 32bit (-/W) */
+#define U300_TIMER_APP_GPT1IA					(0x00a0)
+#define U300_TIMER_APP_GPT1IA_IRQ_ACK				(0x00000080)
+
+/* Reset GP2 Timer 32bit (-/W) */
+#define U300_TIMER_APP_RGPT2					(0x00c0)
+#define U300_TIMER_APP_RGPT2_TIMER_RESET			(0x00000000)
+/* Enable GP2 Timer 32bit (-/W) */
+#define U300_TIMER_APP_EGPT2					(0x00c4)
+#define U300_TIMER_APP_EGPT2_TIMER_ENABLE			(0x00000000)
+/* Disable GP2 Timer 32bit (-/W) */
+#define U300_TIMER_APP_DGPT2					(0x00c8)
+#define U300_TIMER_APP_DGPT2_TIMER_DISABLE			(0x00000000)
+/* GP2 Timer Mode Register 32bit (-/W) */
+#define U300_TIMER_APP_SGPT2M					(0x00cc)
+#define U300_TIMER_APP_SGPT2M_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_SGPT2M_MODE_ONE_SHOT			(0x00000001)
+/* GP2 Timer Status Register 32bit (R/-) */
+#define U300_TIMER_APP_GPT2S					(0x00d0)
+#define U300_TIMER_APP_GPT2S_TIMER_STATE_MASK			(0x0000000F)
+#define U300_TIMER_APP_GPT2S_TIMER_STATE_IDLE			(0x00000001)
+#define U300_TIMER_APP_GPT2S_TIMER_STATE_ACTIVE			(0x00000002)
+#define U300_TIMER_APP_GPT2S_ENABLE_IND				(0x00000010)
+#define U300_TIMER_APP_GPT2S_MODE_MASK				(0x00000020)
+#define U300_TIMER_APP_GPT2S_MODE_CONTINUOUS			(0x00000000)
+#define U300_TIMER_APP_GPT2S_MODE_ONE_SHOT			(0x00000020)
+#define U300_TIMER_APP_GPT2S_IRQ_ENABLED_IND			(0x00000040)
+#define U300_TIMER_APP_GPT2S_IRQ_PENDING_IND			(0x00000080)
+/* GP2 Timer Current Count Register 32bit (R/-) */
+#define U300_TIMER_APP_GPT2CC					(0x00d4)
+/* GP2 Timer Terminal Count Register 32bit (R/W) */
+#define U300_TIMER_APP_GPT2TC					(0x00d8)
+/* GP2 Timer Interrupt Enable Register 32bit (-/W) */
+#define U300_TIMER_APP_GPT2IE					(0x00dc)
+#define U300_TIMER_APP_GPT2IE_IRQ_DISABLE			(0x00000000)
+#define U300_TIMER_APP_GPT2IE_IRQ_ENABLE			(0x00000001)
+/* GP2 Timer Interrupt Acknowledge Register 32bit (-/W) */
+#define U300_TIMER_APP_GPT2IA					(0x00e0)
+#define U300_TIMER_APP_GPT2IA_IRQ_ACK				(0x00000080)
+
+/* Clock request control register - all four timers */
+#define U300_TIMER_APP_CRC					(0x100)
+#define U300_TIMER_APP_CRC_CLOCK_REQUEST_ENABLE			(0x00000001)
+
+static void __iomem *u300_timer_base;
+
+struct u300_clockevent_data {
+	struct clock_event_device cevd;
+	unsigned ticks_per_jiffy;
+};
+
+/*
+ * The u300_set_mode() function is always called first, if we
+ * have oneshot timer active, the oneshot scheduling function
+ * u300_set_next_event() is called immediately after.
+ */
+static void u300_set_mode(enum clock_event_mode mode,
+			  struct clock_event_device *evt)
+{
+	struct u300_clockevent_data *cevdata =
+		container_of(evt, struct u300_clockevent_data, cevd);
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		/* Disable interrupts on GPT1 */
+		writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
+		       u300_timer_base + U300_TIMER_APP_GPT1IE);
+		/* Disable GP1 while we're reprogramming it. */
+		writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
+		       u300_timer_base + U300_TIMER_APP_DGPT1);
+		/*
+		 * Set the periodic mode to a certain number of ticks per
+		 * jiffy.
+		 */
+		writel(cevdata->ticks_per_jiffy,
+		       u300_timer_base + U300_TIMER_APP_GPT1TC);
+		/*
+		 * Set continuous mode, so the timer keeps triggering
+		 * interrupts.
+		 */
+		writel(U300_TIMER_APP_SGPT1M_MODE_CONTINUOUS,
+		       u300_timer_base + U300_TIMER_APP_SGPT1M);
+		/* Enable timer interrupts */
+		writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
+		       u300_timer_base + U300_TIMER_APP_GPT1IE);
+		/* Then enable the OS timer again */
+		writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
+		       u300_timer_base + U300_TIMER_APP_EGPT1);
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		/* Just break; here? */
+		/*
+		 * The actual event will be programmed by the next event hook,
+		 * so we just set a dummy value somewhere at the end of the
+		 * universe here.
+		 */
+		/* Disable interrupts on GPT1 */
+		writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
+		       u300_timer_base + U300_TIMER_APP_GPT1IE);
+		/* Disable GP1 while we're reprogramming it. */
+		writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
+		       u300_timer_base + U300_TIMER_APP_DGPT1);
+		/*
+		 * Expire far in the future, u300_set_next_event() will be
+		 * called soon...
+		 */
+		writel(0xFFFFFFFF, u300_timer_base + U300_TIMER_APP_GPT1TC);
+		/* We run one shot per tick here! */
+		writel(U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT,
+		       u300_timer_base + U300_TIMER_APP_SGPT1M);
+		/* Enable interrupts for this timer */
+		writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
+		       u300_timer_base + U300_TIMER_APP_GPT1IE);
+		/* Enable timer */
+		writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
+		       u300_timer_base + U300_TIMER_APP_EGPT1);
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		/* Disable interrupts on GP1 */
+		writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
+		       u300_timer_base + U300_TIMER_APP_GPT1IE);
+		/* Disable GP1 */
+		writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
+		       u300_timer_base + U300_TIMER_APP_DGPT1);
+		break;
+	case CLOCK_EVT_MODE_RESUME:
+		/* Ignore this call */
+		break;
+	}
+}
+
+/*
+ * The app timer in one shot mode obviously has to be reprogrammed
+ * in EXACTLY this sequence to work properly. Do NOT try to e.g. replace
+ * the interrupt disable + timer disable commands with a reset command,
+ * it will fail miserably. Apparently (and I found this the hard way)
+ * the timer is very sensitive to the instruction order, though you don't
+ * get that impression from the data sheet.
+ */
+static int u300_set_next_event(unsigned long cycles,
+			       struct clock_event_device *evt)
+
+{
+	/* Disable interrupts on GPT1 */
+	writel(U300_TIMER_APP_GPT1IE_IRQ_DISABLE,
+	       u300_timer_base + U300_TIMER_APP_GPT1IE);
+	/* Disable GP1 while we're reprogramming it. */
+	writel(U300_TIMER_APP_DGPT1_TIMER_DISABLE,
+	       u300_timer_base + U300_TIMER_APP_DGPT1);
+	/* Reset the General Purpose timer 1. */
+	writel(U300_TIMER_APP_RGPT1_TIMER_RESET,
+	       u300_timer_base + U300_TIMER_APP_RGPT1);
+	/* IRQ in n * cycles */
+	writel(cycles, u300_timer_base + U300_TIMER_APP_GPT1TC);
+	/*
+	 * We run one shot per tick here! (This is necessary to reconfigure,
+	 * the timer will tilt if you don't!)
+	 */
+	writel(U300_TIMER_APP_SGPT1M_MODE_ONE_SHOT,
+	       u300_timer_base + U300_TIMER_APP_SGPT1M);
+	/* Enable timer interrupts */
+	writel(U300_TIMER_APP_GPT1IE_IRQ_ENABLE,
+	       u300_timer_base + U300_TIMER_APP_GPT1IE);
+	/* Then enable the OS timer again */
+	writel(U300_TIMER_APP_EGPT1_TIMER_ENABLE,
+	       u300_timer_base + U300_TIMER_APP_EGPT1);
+	return 0;
+}
+
+static struct u300_clockevent_data u300_clockevent_data = {
+	/* Use general purpose timer 1 as clock event */
+	.cevd = {
+		.name		= "GPT1",
+		/* Reasonably fast and accurate clock event */
+		.rating		= 300,
+		.features	= CLOCK_EVT_FEAT_PERIODIC |
+			CLOCK_EVT_FEAT_ONESHOT,
+		.set_next_event	= u300_set_next_event,
+		.set_mode	= u300_set_mode,
+	},
+};
+
+/* Clock event timer interrupt handler */
+static irqreturn_t u300_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = &u300_clockevent_data.cevd;
+	/* ACK/Clear timer IRQ for the APP GPT1 Timer */
+
+	writel(U300_TIMER_APP_GPT1IA_IRQ_ACK,
+		u300_timer_base + U300_TIMER_APP_GPT1IA);
+	evt->event_handler(evt);
+	return IRQ_HANDLED;
+}
+
+static struct irqaction u300_timer_irq = {
+	.name		= "U300 Timer Tick",
+	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+	.handler	= u300_timer_interrupt,
+};
+
+/*
+ * Override the global weak sched_clock symbol with this
+ * local implementation which uses the clocksource to get some
+ * better resolution when scheduling the kernel. We accept that
+ * this wraps around for now, since it is just a relative time
+ * stamp. (Inspired by OMAP implementation.)
+ */
+
+static u64 notrace u300_read_sched_clock(void)
+{
+	return readl(u300_timer_base + U300_TIMER_APP_GPT2CC);
+}
+
+static unsigned long u300_read_current_timer(void)
+{
+	return readl(u300_timer_base + U300_TIMER_APP_GPT2CC);
+}
+
+static struct delay_timer u300_delay_timer;
+
+/*
+ * This sets up the system timers, clock source and clock event.
+ */
+static void __init u300_timer_init_of(struct device_node *np)
+{
+	unsigned int irq;
+	struct clk *clk;
+	unsigned long rate;
+
+	u300_timer_base = of_iomap(np, 0);
+	if (!u300_timer_base)
+		panic("could not ioremap system timer\n");
+
+	/* Get the IRQ for the GP1 timer */
+	irq = irq_of_parse_and_map(np, 2);
+	if (!irq)
+		panic("no IRQ for system timer\n");
+
+	pr_info("U300 GP1 timer @ base: %p, IRQ: %u\n", u300_timer_base, irq);
+
+	/* Clock the interrupt controller */
+	clk = of_clk_get(np, 0);
+	BUG_ON(IS_ERR(clk));
+	clk_prepare_enable(clk);
+	rate = clk_get_rate(clk);
+
+	u300_clockevent_data.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
+
+	sched_clock_register(u300_read_sched_clock, 32, rate);
+
+	u300_delay_timer.read_current_timer = &u300_read_current_timer;
+	u300_delay_timer.freq = rate;
+	register_current_timer_delay(&u300_delay_timer);
+
+	/*
+	 * Disable the "OS" and "DD" timers - these are designed for Symbian!
+	 * Example usage in cnh1601578 cpu subsystem pd_timer_app.c
+	 */
+	writel(U300_TIMER_APP_CRC_CLOCK_REQUEST_ENABLE,
+		u300_timer_base + U300_TIMER_APP_CRC);
+	writel(U300_TIMER_APP_ROST_TIMER_RESET,
+		u300_timer_base + U300_TIMER_APP_ROST);
+	writel(U300_TIMER_APP_DOST_TIMER_DISABLE,
+		u300_timer_base + U300_TIMER_APP_DOST);
+	writel(U300_TIMER_APP_RDDT_TIMER_RESET,
+		u300_timer_base + U300_TIMER_APP_RDDT);
+	writel(U300_TIMER_APP_DDDT_TIMER_DISABLE,
+		u300_timer_base + U300_TIMER_APP_DDDT);
+
+	/* Reset the General Purpose timer 1. */
+	writel(U300_TIMER_APP_RGPT1_TIMER_RESET,
+		u300_timer_base + U300_TIMER_APP_RGPT1);
+
+	/* Set up the IRQ handler */
+	setup_irq(irq, &u300_timer_irq);
+
+	/* Reset the General Purpose timer 2 */
+	writel(U300_TIMER_APP_RGPT2_TIMER_RESET,
+		u300_timer_base + U300_TIMER_APP_RGPT2);
+	/* Set this timer to run around forever */
+	writel(0xFFFFFFFFU, u300_timer_base + U300_TIMER_APP_GPT2TC);
+	/* Set continuous mode so it wraps around */
+	writel(U300_TIMER_APP_SGPT2M_MODE_CONTINUOUS,
+	       u300_timer_base + U300_TIMER_APP_SGPT2M);
+	/* Disable timer interrupts */
+	writel(U300_TIMER_APP_GPT2IE_IRQ_DISABLE,
+		u300_timer_base + U300_TIMER_APP_GPT2IE);
+	/* Then enable the GP2 timer to use as a free running us counter */
+	writel(U300_TIMER_APP_EGPT2_TIMER_ENABLE,
+		u300_timer_base + U300_TIMER_APP_EGPT2);
+
+	/* Use general purpose timer 2 as clock source */
+	if (clocksource_mmio_init(u300_timer_base + U300_TIMER_APP_GPT2CC,
+			"GPT2", rate, 300, 32, clocksource_mmio_readl_up))
+		pr_err("timer: failed to initialize U300 clock source\n");
+
+	/* Configure and register the clockevent */
+	clockevents_config_and_register(&u300_clockevent_data.cevd, rate,
+					1, 0xffffffff);
+
+	/*
+	 * TODO: init and register the rest of the timers too, they can be
+	 * used by hrtimers!
+	 */
+}
+
+CLOCKSOURCE_OF_DECLARE(u300_timer, "stericsson,u300-apptimer",
+		       u300_timer_init_of);