ARM: mxs: Add timer support

There are 2 versions of the timrot on Freescale MXS-based SoCs.
The v1 on MX23 only gets 16 bits counter, while v2 on MX28
extends the counter to 32 bits.

The implementation uses two timers, one for clock_event and
another for clocksource. MX28 uses timrot 0 and 1, while MX23
uses 0 and 2.
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

arch/arm/mach-mxs/timer.c

+/*
+ *  Copyright (C) 2000-2001 Deep Blue Solutions
+ *  Copyright (C) 2002 Shane Nay (shane@minirl.com)
+ *  Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
+ *  Copyright (C) 2008 Juergen Beisert (kernel@pengutronix.de)
+ *  Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/clockchips.h>
+#include <linux/clk.h>
+
+#include <asm/mach/time.h>
+#include <mach/mxs.h>
+#include <mach/common.h>
+
+/*
+ * There are 2 versions of the timrot on Freescale MXS-based SoCs.
+ * The v1 on MX23 only gets 16 bits counter, while v2 on MX28
+ * extends the counter to 32 bits.
+ *
+ * The implementation uses two timers, one for clock_event and
+ * another for clocksource. MX28 uses timrot 0 and 1, while MX23
+ * uses 0 and 2.
+ */
+
+#define MX23_TIMROT_VERSION_OFFSET	0x0a0
+#define MX28_TIMROT_VERSION_OFFSET	0x120
+#define BP_TIMROT_MAJOR_VERSION		24
+#define BV_TIMROT_VERSION_1		0x01
+#define BV_TIMROT_VERSION_2		0x02
+#define timrot_is_v1()	(timrot_major_version == BV_TIMROT_VERSION_1)
+
+/*
+ * There are 4 registers for each timrotv2 instance, and 2 registers
+ * for each timrotv1. So address step 0x40 in macros below strides
+ * one instance of timrotv2 while two instances of timrotv1.
+ *
+ * As the result, HW_TIMROT_XXXn(1) defines the address of timrot1
+ * on MX28 while timrot2 on MX23.
+ */
+/* common between v1 and v2 */
+#define HW_TIMROT_ROTCTRL		0x00
+#define HW_TIMROT_TIMCTRLn(n)		(0x20 + (n) * 0x40)
+/* v1 only */
+#define HW_TIMROT_TIMCOUNTn(n)		(0x30 + (n) * 0x40)
+/* v2 only */
+#define HW_TIMROT_RUNNING_COUNTn(n)	(0x30 + (n) * 0x40)
+#define HW_TIMROT_FIXED_COUNTn(n)	(0x40 + (n) * 0x40)
+
+#define BM_TIMROT_TIMCTRLn_RELOAD	(1 << 6)
+#define BM_TIMROT_TIMCTRLn_UPDATE	(1 << 7)
+#define BM_TIMROT_TIMCTRLn_IRQ_EN	(1 << 14)
+#define BM_TIMROT_TIMCTRLn_IRQ		(1 << 15)
+#define BP_TIMROT_TIMCTRLn_SELECT	0
+#define BV_TIMROTv1_TIMCTRLn_SELECT__32KHZ_XTAL	0x8
+#define BV_TIMROTv2_TIMCTRLn_SELECT__32KHZ_XTAL	0xb
+
+static struct clock_event_device mxs_clockevent_device;
+static enum clock_event_mode mxs_clockevent_mode = CLOCK_EVT_MODE_UNUSED;
+
+static void __iomem *mxs_timrot_base = MXS_IO_ADDRESS(MXS_TIMROT_BASE_ADDR);
+static u32 timrot_major_version;
+
+static inline void timrot_irq_disable(void)
+{
+	__mxs_clrl(BM_TIMROT_TIMCTRLn_IRQ_EN,
+			mxs_timrot_base + HW_TIMROT_TIMCTRLn(0));
+}
+
+static inline void timrot_irq_enable(void)
+{
+	__mxs_setl(BM_TIMROT_TIMCTRLn_IRQ_EN,
+			mxs_timrot_base + HW_TIMROT_TIMCTRLn(0));
+}
+
+static void timrot_irq_acknowledge(void)
+{
+	__mxs_clrl(BM_TIMROT_TIMCTRLn_IRQ,
+			mxs_timrot_base + HW_TIMROT_TIMCTRLn(0));
+}
+
+static cycle_t timrotv1_get_cycles(struct clocksource *cs)
+{
+	return ~((__raw_readl(mxs_timrot_base + HW_TIMROT_TIMCOUNTn(1))
+			& 0xffff0000) >> 16);
+}
+
+static cycle_t timrotv2_get_cycles(struct clocksource *cs)
+{
+	return ~__raw_readl(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1));
+}
+
+static int timrotv1_set_next_event(unsigned long evt,
+					struct clock_event_device *dev)
+{
+	/* timrot decrements the count */
+	__raw_writel(evt, mxs_timrot_base + HW_TIMROT_TIMCOUNTn(0));
+
+	return 0;
+}
+
+static int timrotv2_set_next_event(unsigned long evt,
+					struct clock_event_device *dev)
+{
+	/* timrot decrements the count */
+	__raw_writel(evt, mxs_timrot_base + HW_TIMROT_FIXED_COUNTn(0));
+
+	return 0;
+}
+
+static irqreturn_t mxs_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+
+	timrot_irq_acknowledge();
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction mxs_timer_irq = {
+	.name		= "MXS Timer Tick",
+	.dev_id		= &mxs_clockevent_device,
+	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
+	.handler	= mxs_timer_interrupt,
+};
+
+#ifdef DEBUG
+static const char *clock_event_mode_label[] const = {
+	[CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
+	[CLOCK_EVT_MODE_ONESHOT]  = "CLOCK_EVT_MODE_ONESHOT",
+	[CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
+	[CLOCK_EVT_MODE_UNUSED]   = "CLOCK_EVT_MODE_UNUSED"
+};
+#endif /* DEBUG */
+
+static void mxs_set_mode(enum clock_event_mode mode,
+				struct clock_event_device *evt)
+{
+	/* Disable interrupt in timer module */
+	timrot_irq_disable();
+
+	if (mode != mxs_clockevent_mode) {
+		/* Set event time into the furthest future */
+		if (timrot_is_v1())
+			__raw_writel(0xffff,
+				mxs_timrot_base + HW_TIMROT_TIMCOUNTn(1));
+		else
+			__raw_writel(0xffffffff,
+				mxs_timrot_base + HW_TIMROT_FIXED_COUNTn(1));
+
+		/* Clear pending interrupt */
+		timrot_irq_acknowledge();
+	}
+
+#ifdef DEBUG
+	pr_info("%s: changing mode from %s to %s\n", __func__,
+		clock_event_mode_label[mxs_clockevent_mode],
+		clock_event_mode_label[mode]);
+#endif /* DEBUG */
+
+	/* Remember timer mode */
+	mxs_clockevent_mode = mode;
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		pr_err("%s: Periodic mode is not implemented\n", __func__);
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		timrot_irq_enable();
+		break;
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_RESUME:
+		/* Left event sources disabled, no more interrupts appear */
+		break;
+	}
+}
+
+static struct clock_event_device mxs_clockevent_device = {
+	.name		= "mxs_timrot",
+	.features	= CLOCK_EVT_FEAT_ONESHOT,
+	.shift		= 32,
+	.set_mode	= mxs_set_mode,
+	.set_next_event	= timrotv2_set_next_event,
+	.rating		= 200,
+};
+
+static int __init mxs_clockevent_init(struct clk *timer_clk)
+{
+	unsigned int c = clk_get_rate(timer_clk);
+
+	mxs_clockevent_device.mult =
+		div_sc(c, NSEC_PER_SEC, mxs_clockevent_device.shift);
+	mxs_clockevent_device.cpumask = cpumask_of(0);
+	if (timrot_is_v1()) {
+		mxs_clockevent_device.set_next_event = timrotv1_set_next_event;
+		mxs_clockevent_device.max_delta_ns =
+			clockevent_delta2ns(0xfffe, &mxs_clockevent_device);
+		mxs_clockevent_device.min_delta_ns =
+			clockevent_delta2ns(0xf, &mxs_clockevent_device);
+	} else {
+		mxs_clockevent_device.max_delta_ns =
+			clockevent_delta2ns(0xfffffffe, &mxs_clockevent_device);
+		mxs_clockevent_device.min_delta_ns =
+			clockevent_delta2ns(0xf, &mxs_clockevent_device);
+	}
+
+	clockevents_register_device(&mxs_clockevent_device);
+
+	return 0;
+}
+
+static struct clocksource clocksource_mxs = {
+	.name		= "mxs_timer",
+	.rating		= 200,
+	.read		= timrotv2_get_cycles,
+	.mask		= CLOCKSOURCE_MASK(32),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init mxs_clocksource_init(struct clk *timer_clk)
+{
+	unsigned int c = clk_get_rate(timer_clk);
+
+	if (timrot_is_v1()) {
+		clocksource_mxs.read = timrotv1_get_cycles;
+		clocksource_mxs.mask = CLOCKSOURCE_MASK(16);
+	}
+
+	clocksource_register_hz(&clocksource_mxs, c);
+
+	return 0;
+}
+
+void __init mxs_timer_init(struct clk *timer_clk, int irq)
+{
+	clk_enable(timer_clk);
+
+	/*
+	 * Initialize timers to a known state
+	 */
+	mxs_reset_block(mxs_timrot_base + HW_TIMROT_ROTCTRL);
+
+	/* get timrot version */
+	timrot_major_version = __raw_readl(mxs_timrot_base +
+				(cpu_is_mx23() ? MX23_TIMROT_VERSION_OFFSET :
+						MX28_TIMROT_VERSION_OFFSET));
+	timrot_major_version >>= BP_TIMROT_MAJOR_VERSION;
+
+	/* one for clock_event */
+	__raw_writel((timrot_is_v1() ?
+			BV_TIMROTv1_TIMCTRLn_SELECT__32KHZ_XTAL :
+			BV_TIMROTv2_TIMCTRLn_SELECT__32KHZ_XTAL) |
+			BM_TIMROT_TIMCTRLn_UPDATE |
+			BM_TIMROT_TIMCTRLn_IRQ_EN,
+			mxs_timrot_base + HW_TIMROT_TIMCTRLn(0));
+
+	/* another for clocksource */
+	__raw_writel((timrot_is_v1() ?
+			BV_TIMROTv1_TIMCTRLn_SELECT__32KHZ_XTAL :
+			BV_TIMROTv2_TIMCTRLn_SELECT__32KHZ_XTAL) |
+			BM_TIMROT_TIMCTRLn_RELOAD,
+			mxs_timrot_base + HW_TIMROT_TIMCTRLn(1));
+
+	/* set clocksource timer fixed count to the maximum */
+	if (timrot_is_v1())
+		__raw_writel(0xffff,
+			mxs_timrot_base + HW_TIMROT_TIMCOUNTn(1));
+	else
+		__raw_writel(0xffffffff,
+			mxs_timrot_base + HW_TIMROT_FIXED_COUNTn(1));
+
+	/* init and register the timer to the framework */
+	mxs_clocksource_init(timer_clk);
+	mxs_clockevent_init(timer_clk);
+
+	/* Make irqs happen */
+	setup_irq(irq, &mxs_timer_irq);
+}