i.MXC family: Adding timer support

This patch adds timer support for the i.MX machine family. This code can
be used on the following machs:

 - i.MX1 (tested)
 - i.MX2 (i.MX21 (to be tested), i.MX27 (tested))
 - i.MX3 (i.MX31 (tested))

TODO: It seems impossible to build a kernel for more than one CPU because the
timer do not follow the platform device rules. So it does only work if
timer 1 can be accessed on all CPUs at the same address.

Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

6 files changed, 244 insertions, 151 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5c8c1a89be7..8a9a84c4adf 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -367,6 +367,8 @@ config ARCH_NS9XXX
 
 config ARCH_MXC
         bool "Freescale MXC/iMX-based"
+        select GENERIC_TIME
+        select GENERIC_CLOCKEVENTS
         select ARCH_MTD_XIP
         select GENERIC_GPIO
         select HAVE_GPIO_LIB
diff --git a/arch/arm/mach-mx3/Makefile b/arch/arm/mach-mx3/Makefile
index 68f062b70d3..562c75d2e37 100644
--- a/arch/arm/mach-mx3/Makefile
+++ b/arch/arm/mach-mx3/Makefile
@@ -4,5 +4,5 @@
 
 # Object file lists.
 
-obj-y                   := mm.o time.o clock.o devices.o iomux.o
+obj-y                   := mm.o clock.o devices.o iomux.o
 obj-$(CONFIG_MACH_MX31ADS)      += mx31ads.o
diff --git a/arch/arm/mach-mx3/mx31ads.c b/arch/arm/mach-mx3/mx31ads.c
index 5addbb7f711..eba3e0cd428 100644
--- a/arch/arm/mach-mx3/mx31ads.c
+++ b/arch/arm/mach-mx3/mx31ads.c
@@ -26,6 +26,7 @@
 #include <asm/hardware.h>
 #include <asm/mach-types.h>
 #include <asm/mach/arch.h>
+#include <asm/mach/time.h>
 #include <asm/memory.h>
 #include <asm/mach/map.h>
 #include <asm/arch/common.h>
@@ -127,6 +128,16 @@ static void __init mxc_board_init(void)
         mxc_init_extuart();
 }
 
+static void __init mx31ads_timer_init(void)
+{
+        mxc_clocks_init(26000000);
+        mxc_timer_init("ipg_clk.0");
+}
+
+struct sys_timer mx31ads_timer = {
+        .init   = mx31ads_timer_init,
+};
+
 /*
  * The following uses standard kernel macros defined in arch.h in order to
  * initialize __mach_desc_MX31ADS data structure.
@@ -139,5 +150,5 @@ MACHINE_START(MX31ADS, "Freescale MX31ADS")
         .map_io         = mx31ads_map_io,
         .init_irq       = mxc_init_irq,
         .init_machine   = mxc_board_init,
-        .timer          = &mxc_timer,
+        .timer          = &mx31ads_timer,
 MACHINE_END
diff --git a/arch/arm/mach-mx3/time.c b/arch/arm/mach-mx3/time.c
deleted file mode 100644
index fb565c98dbf..00000000000
--- a/arch/arm/mach-mx3/time.c
+++ /dev/null
@@ -1,148 +0,0 @@
-/*
- * System Timer Interrupt reconfigured to run in free-run mode.
- * Author: Vitaly Wool
- * Copyright 2004 MontaVista Software Inc.
- * Copyright 2004-2007 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 version 2 as
- * published by the Free Software Foundation.
- */
-
-/*!
- * @file time.c
- * @brief This file contains OS tick and wdog timer implementations.
- *
- * This file contains OS tick and wdog timer implementations.
- *
- * @ingroup Timers
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/irq.h>
-#include <asm/hardware.h>
-#include <asm/mach/time.h>
-#include <asm/io.h>
-#include <asm/arch/common.h>
-
-/*!
- * This is the timer interrupt service routine to do required tasks.
- * It also services the WDOG timer at the frequency of twice per WDOG
- * timeout value. For example, if the WDOG's timeout value is 4 (2
- * seconds since the WDOG runs at 0.5Hz), it will be serviced once
- * every 2/2=1 second.
- *
- * @param  irq          GPT interrupt source number (not used)
- * @param  dev_id       this parameter is not used
- * @return always returns \b IRQ_HANDLED as defined in
- *         include/linux/interrupt.h.
- */
-static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id)
-{
-        unsigned int next_match;
-
-        if (__raw_readl(MXC_GPT_GPTSR) & GPTSR_OF1) {
-                do {
-                        timer_tick();
-                        next_match = __raw_readl(MXC_GPT_GPTOCR1) + LATCH;
-                        __raw_writel(GPTSR_OF1, MXC_GPT_GPTSR);
-                        __raw_writel(next_match, MXC_GPT_GPTOCR1);
-                } while ((signed long)(next_match -
-                                       __raw_readl(MXC_GPT_GPTCNT)) <= 0);
-        }
-
-        return IRQ_HANDLED;
-}
-
-/*!
- * This function is used to obtain the number of microseconds since the last
- * timer interrupt. Note that interrupts is disabled by do_gettimeofday().
- *
- * @return the number of microseconds since the last timer interrupt.
- */
-static unsigned long mxc_gettimeoffset(void)
-{
-        unsigned long ticks_to_match, elapsed, usec, tick_usec, i;
-
-        /* Get ticks before next timer match */
-        ticks_to_match =
-            __raw_readl(MXC_GPT_GPTOCR1) - __raw_readl(MXC_GPT_GPTCNT);
-
-        /* We need elapsed ticks since last match */
-        elapsed = LATCH - ticks_to_match;
-
-        /* Now convert them to usec */
-        /* Insure no overflow when calculating the usec below */
-        for (i = 1, tick_usec = tick_nsec / 1000;; i *= 2) {
-                tick_usec /= i;
-                if ((0xFFFFFFFF / tick_usec) > elapsed)
-                        break;
-        }
-        usec = (unsigned long)(elapsed * tick_usec) / (LATCH / i);
-
-        return usec;
-}
-
-/*!
- * The OS tick timer interrupt structure.
- */
-static struct irqaction timer_irq = {
-        .name = "MXC Timer Tick",
-        .flags = IRQF_DISABLED | IRQF_TIMER,
-        .handler = mxc_timer_interrupt
-};
-
-/*!
- * This function is used to initialize the GPT to produce an interrupt
- * based on HZ.  It is called by start_kernel() during system startup.
- */
-void __init mxc_init_time(void)
-{
-        u32 reg, v;
-        reg = __raw_readl(MXC_GPT_GPTCR);
-        reg &= ~GPTCR_ENABLE;
-        __raw_writel(reg, MXC_GPT_GPTCR);
-        reg |= GPTCR_SWR;
-        __raw_writel(reg, MXC_GPT_GPTCR);
-
-        while ((__raw_readl(MXC_GPT_GPTCR) & GPTCR_SWR) != 0)
-                cpu_relax();
-
-        reg = GPTCR_FRR | GPTCR_CLKSRC_HIGHFREQ;
-        __raw_writel(reg, MXC_GPT_GPTCR);
-
-        /* TODO: get timer rate from clk driver */
-        v = 66500000;
-
-        __raw_writel((v / CLOCK_TICK_RATE) - 1, MXC_GPT_GPTPR);
-
-        if ((v % CLOCK_TICK_RATE) != 0) {
-                pr_info("\nWARNING: Can't generate CLOCK_TICK_RATE at %d Hz\n",
-                        CLOCK_TICK_RATE);
-        }
-        pr_info("Actual CLOCK_TICK_RATE is %d Hz\n",
-                v / ((__raw_readl(MXC_GPT_GPTPR) & 0xFFF) + 1));
-
-        reg = __raw_readl(MXC_GPT_GPTCNT);
-        reg += LATCH;
-        __raw_writel(reg, MXC_GPT_GPTOCR1);
-
-        setup_irq(MXC_INT_GPT, &timer_irq);
-
-        reg = __raw_readl(MXC_GPT_GPTCR);
-        reg =
-            GPTCR_FRR | GPTCR_CLKSRC_HIGHFREQ | GPTCR_STOPEN | GPTCR_DOZEN |
-            GPTCR_WAITEN | GPTCR_ENMOD | GPTCR_ENABLE;
-        __raw_writel(reg, MXC_GPT_GPTCR);
-
-        __raw_writel(GPTIR_OF1IE, MXC_GPT_GPTIR);
-}
-
-struct sys_timer mxc_timer = {
-        .init = mxc_init_time,
-        .offset = mxc_gettimeoffset,
-};
diff --git a/arch/arm/plat-mxc/Makefile b/arch/arm/plat-mxc/Makefile
index 66272a6fc32..e3cc25c6d46 100644
--- a/arch/arm/plat-mxc/Makefile
+++ b/arch/arm/plat-mxc/Makefile
@@ -3,4 +3,4 @@
 #
 
 # Common support
-obj-y := irq.o clock.o gpio.o
+obj-y := irq.o clock.o gpio.o time.o
diff --git a/arch/arm/plat-mxc/time.c b/arch/arm/plat-mxc/time.c
new file mode 100644
index 00000000000..3bf86343fdf
--- /dev/null
+++ b/arch/arm/plat-mxc/time.c
@@ -0,0 +1,228 @@
+/*
+ *  linux/arch/arm/plat-mxc/time.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)
+ *
+ * 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/hardware.h>
+#include <asm/mach/time.h>
+#include <asm/arch/common.h>
+#include <asm/arch/mxc_timer.h>
+
+static struct clock_event_device clockevent_mxc;
+static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
+
+/* clock source for the timer */
+static struct clk *timer_clk;
+
+/* clock source */
+
+static cycle_t mxc_get_cycles(void)
+{
+        return __raw_readl(TIMER_BASE + MXC_TCN);
+}
+
+static struct clocksource clocksource_mxc = {
+        .name           = "mxc_timer1",
+        .rating         = 200,
+        .read           = mxc_get_cycles,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .shift          = 20,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init mxc_clocksource_init(void)
+{
+        unsigned int clock;
+
+        clock = clk_get_rate(timer_clk);
+
+        clocksource_mxc.mult = clocksource_hz2mult(clock,
+                                        clocksource_mxc.shift);
+        clocksource_register(&clocksource_mxc);
+
+        return 0;
+}
+
+/* clock event */
+
+static int mxc_set_next_event(unsigned long evt,
+                              struct clock_event_device *unused)
+{
+        unsigned long tcmp;
+
+        tcmp = __raw_readl(TIMER_BASE + MXC_TCN) + evt;
+        __raw_writel(tcmp, TIMER_BASE + MXC_TCMP);
+
+        return (int)(tcmp - __raw_readl(TIMER_BASE + MXC_TCN)) < 0 ?
+                                -ETIME : 0;
+}
+
+#ifdef DEBUG
+static const char *clock_event_mode_label[] = {
+        [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 mxc_set_mode(enum clock_event_mode mode,
+                                struct clock_event_device *evt)
+{
+        unsigned long flags;
+
+        /*
+         * The timer interrupt generation is disabled at least
+         * for enough time to call mxc_set_next_event()
+         */
+        local_irq_save(flags);
+
+        /* Disable interrupt in GPT module */
+        gpt_irq_disable();
+
+        if (mode != clockevent_mode) {
+                /* Set event time into far-far future */
+                __raw_writel(__raw_readl(TIMER_BASE + MXC_TCN) - 3,
+                                TIMER_BASE + MXC_TCMP);
+                /* Clear pending interrupt */
+                gpt_irq_acknowledge();
+        }
+
+#ifdef DEBUG
+        printk(KERN_INFO "mxc_set_mode: changing mode from %s to %s\n",
+                clock_event_mode_label[clockevent_mode],
+                clock_event_mode_label[mode]);
+#endif /* DEBUG */
+
+        /* Remember timer mode */
+        clockevent_mode = mode;
+        local_irq_restore(flags);
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                printk(KERN_ERR"mxc_set_mode: Periodic mode is not "
+                                "supported for i.MX\n");
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+        /*
+         * Do not put overhead of interrupt enable/disable into
+         * mxc_set_next_event(), the core has about 4 minutes
+         * to call mxc_set_next_event() or shutdown clock after
+         * mode switching
+         */
+                local_irq_save(flags);
+                gpt_irq_enable();
+                local_irq_restore(flags);
+                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;
+        }
+}
+
+/*
+ * IRQ handler for the timer
+ */
+static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = &clockevent_mxc;
+        uint32_t tstat;
+
+        tstat = __raw_readl(TIMER_BASE + MXC_TSTAT);
+
+        gpt_irq_acknowledge();
+
+        evt->event_handler(evt);
+
+        return IRQ_HANDLED;
+}
+
+static struct irqaction mxc_timer_irq = {
+        .name           = "i.MX Timer Tick",
+        .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+        .handler        = mxc_timer_interrupt,
+};
+
+static struct clock_event_device clockevent_mxc = {
+        .name           = "mxc_timer1",
+        .features       = CLOCK_EVT_FEAT_ONESHOT,
+        .shift          = 32,
+        .set_mode       = mxc_set_mode,
+        .set_next_event = mxc_set_next_event,
+        .rating         = 200,
+};
+
+static int __init mxc_clockevent_init(void)
+{
+        unsigned int clock;
+
+        clock = clk_get_rate(timer_clk);
+
+        clockevent_mxc.mult = div_sc(clock, NSEC_PER_SEC,
+                                        clockevent_mxc.shift);
+        clockevent_mxc.max_delta_ns =
+                        clockevent_delta2ns(0xfffffffe, &clockevent_mxc);
+        clockevent_mxc.min_delta_ns =
+                        clockevent_delta2ns(0xff, &clockevent_mxc);
+
+        clockevent_mxc.cpumask = cpumask_of_cpu(0);
+
+        clockevents_register_device(&clockevent_mxc);
+
+        return 0;
+}
+
+void __init mxc_timer_init(const char *clk_timer)
+{
+        timer_clk = clk_get(NULL, clk_timer);
+        if (!timer_clk) {
+                printk(KERN_ERR"Cannot determine timer clock. Giving up.\n");
+                return;
+        }
+
+        clk_enable(timer_clk);
+
+        /*
+         * Initialise to a known state (all timers off, and timing reset)
+         */
+        __raw_writel(0, TIMER_BASE + MXC_TCTL);
+        __raw_writel(0, TIMER_BASE + MXC_TPRER); /* see datasheet note */
+
+        __raw_writel(TCTL_FRR | /* free running */
+                     TCTL_VAL | /* set clocksource and arch specific bits */
+                     TCTL_TEN,  /* start the timer */
+                     TIMER_BASE + MXC_TCTL);
+
+        /* init and register the timer to the framework */
+        mxc_clocksource_init();
+        mxc_clockevent_init();
+
+        /* Make irqs happen */
+        setup_irq(TIMER_INTERRUPT, &mxc_timer_irq);
+}
+