[ARM] smp: allow re-use of realview localtimer TWD support

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 173 insertions, 0 deletions

diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
new file mode 100644
index 000000000000..aabd62d6bd19
--- /dev/null
+++ b/arch/arm/kernel/smp_twd.c
@@ -0,0 +1,173 @@
+/*
+ *  linux/arch/arm/kernel/smp_twd.c
+ *
+ *  Copyright (C) 2002 ARM Ltd.
+ *  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.
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/smp.h>
+#include <linux/jiffies.h>
+#include <linux/clockchips.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+
+#include <asm/smp_twd.h>
+#include <asm/hardware/gic.h>
+
+#define TWD_TIMER_LOAD                  0x00
+#define TWD_TIMER_COUNTER               0x04
+#define TWD_TIMER_CONTROL               0x08
+#define TWD_TIMER_INTSTAT               0x0C
+
+#define TWD_WDOG_LOAD                   0x20
+#define TWD_WDOG_COUNTER                0x24
+#define TWD_WDOG_CONTROL                0x28
+#define TWD_WDOG_INTSTAT                0x2C
+#define TWD_WDOG_RESETSTAT              0x30
+#define TWD_WDOG_DISABLE                0x34
+
+#define TWD_TIMER_CONTROL_ENABLE        (1 << 0)
+#define TWD_TIMER_CONTROL_ONESHOT       (0 << 1)
+#define TWD_TIMER_CONTROL_PERIODIC      (1 << 1)
+#define TWD_TIMER_CONTROL_IT_ENABLE     (1 << 2)
+
+/* set up by the platform code */
+void __iomem *twd_base;
+
+static unsigned long twd_timer_rate;
+
+static void twd_set_mode(enum clock_event_mode mode,
+                        struct clock_event_device *clk)
+{
+        unsigned long ctrl;
+
+        switch(mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                /* timer load already set up */
+                ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
+                        | TWD_TIMER_CONTROL_PERIODIC;
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+                /* period set, and timer enabled in 'next_event' hook */
+                ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
+                break;
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        default:
+                ctrl = 0;
+        }
+
+        __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
+}
+
+static int twd_set_next_event(unsigned long evt,
+                        struct clock_event_device *unused)
+{
+        unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
+
+        __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
+        __raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, twd_base + TWD_TIMER_CONTROL);
+
+        return 0;
+}
+
+/*
+ * local_timer_ack: checks for a local timer interrupt.
+ *
+ * If a local timer interrupt has occurred, acknowledge and return 1.
+ * Otherwise, return 0.
+ */
+int twd_timer_ack(void)
+{
+        if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
+                __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
+                return 1;
+        }
+
+        return 0;
+}
+
+static void __cpuinit twd_calibrate_rate(void)
+{
+        unsigned long load, count;
+        u64 waitjiffies;
+
+        /*
+         * If this is the first time round, we need to work out how fast
+         * the timer ticks
+         */
+        if (twd_timer_rate == 0) {
+                printk("Calibrating local timer... ");
+
+                /* Wait for a tick to start */
+                waitjiffies = get_jiffies_64() + 1;
+
+                while (get_jiffies_64() < waitjiffies)
+                        udelay(10);
+
+                /* OK, now the tick has started, let's get the timer going */
+                waitjiffies += 5;
+
+                                 /* enable, no interrupt or reload */
+                __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
+
+                                 /* maximum value */
+                __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
+
+                while (get_jiffies_64() < waitjiffies)
+                        udelay(10);
+
+                count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
+
+                twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
+
+                printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
+                        (twd_timer_rate / 100000) % 100);
+        }
+
+        load = twd_timer_rate / HZ;
+
+        __raw_writel(load, twd_base + TWD_TIMER_LOAD);
+}
+
+/*
+ * Setup the local clock events for a CPU.
+ */
+void __cpuinit twd_timer_setup(struct clock_event_device *clk)
+{
+        unsigned long flags;
+
+        twd_calibrate_rate();
+
+        clk->name               = "local_timer";
+        clk->features           = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+        clk->rating             = 350;
+        clk->set_mode           = twd_set_mode;
+        clk->set_next_event     = twd_set_next_event;
+        clk->shift              = 20;
+        clk->mult               = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift);
+        clk->max_delta_ns       = clockevent_delta2ns(0xffffffff, clk);
+        clk->min_delta_ns       = clockevent_delta2ns(0xf, clk);
+
+        /* Make sure our local interrupt controller has this enabled */
+        local_irq_save(flags);
+        get_irq_chip(clk->irq)->unmask(clk->irq);
+        local_irq_restore(flags);
+
+        clockevents_register_device(clk);
+}
+
+/*
+ * take a local timer down
+ */
+void __cpuexit twd_timer_stop(void)
+{
+        __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
+}