[ARM] 4815/1: RealView: Add clockevents suport for the local timers
authorCatalin Marinas <catalin.marinas@arm.com>
Mon, 4 Feb 2008 16:32:57 +0000 (17:32 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Mon, 4 Feb 2008 17:52:20 +0000 (17:52 +0000)
This patch registers the local timers on ARM11MPCore as clock event
devices. The clock device can be set up as periodic or oneshot.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arch/arm/mach-realview/localtimer.c
include/asm-arm/hardware/arm_twd.h

index 529eb6979e614cab73b9cf61b2d6cc968cc69ea9..4f87b4d09c7d207b1649f6e7913d7b28b14a06da 100644 (file)
@@ -16,8 +16,8 @@
 #include <linux/jiffies.h>
 #include <linux/percpu.h>
 #include <linux/clockchips.h>
+#include <linux/irq.h>
 
-#include <asm/mach/time.h>
 #include <asm/hardware/arm_twd.h>
 #include <asm/hardware/gic.h>
 #include <asm/hardware.h>
@@ -43,6 +43,43 @@ void local_timer_interrupt(void)
 
 static unsigned long mpcore_timer_rate;
 
+static void local_timer_set_mode(enum clock_event_mode mode,
+                                struct clock_event_device *clk)
+{
+       void __iomem *base = TWD_BASE(smp_processor_id());
+       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, base + TWD_TIMER_CONTROL);
+}
+
+static int local_timer_set_next_event(unsigned long evt,
+                                     struct clock_event_device *unused)
+{
+       void __iomem *base = TWD_BASE(smp_processor_id());
+       unsigned long ctrl = __raw_readl(base + TWD_TIMER_CONTROL);
+
+       __raw_writel(evt, base + TWD_TIMER_COUNTER);
+       __raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, base + TWD_TIMER_CONTROL);
+
+       return 0;
+}
+
 /*
  * local_timer_ack: checks for a local timer interrupt.
  *
@@ -61,12 +98,11 @@ int local_timer_ack(void)
        return 0;
 }
 
-void __cpuinit local_timer_setup(unsigned int cpu)
+static void __cpuinit twd_calibrate_rate(unsigned int cpu)
 {
        void __iomem *base = TWD_BASE(cpu);
-       unsigned int load, offset;
+       unsigned long load, count;
        u64 waitjiffies;
-       unsigned int count;
 
        /*
         * If this is the first time round, we need to work out how fast
@@ -104,36 +140,36 @@ void __cpuinit local_timer_setup(unsigned int cpu)
        load = mpcore_timer_rate / HZ;
 
        __raw_writel(load, base + TWD_TIMER_LOAD);
-       __raw_writel(0x7,  base + TWD_TIMER_CONTROL);
-
-       /*
-        * Now maneuver our local tick into the right part of the jiffy.
-        * Start by working out where within the tick our local timer
-        * interrupt should go.
-        */
-       offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1);
+}
 
-       /*
-        * gettimeoffset() will return a number of us since the last tick.
-        * Convert this number of us to a local timer tick count.
-        * Be careful of integer overflow whilst keeping maximum precision.
-        *
-        * with HZ=100 and 1MHz (fpga) ~ 1GHz processor:
-        * load = 1 ~ 10,000
-        * mpcore_timer_rate/10000 = 100 ~ 100,000
-        *
-        * so the multiply value will be less than 10^9 always.
-        */
-       load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100;
+/*
+ * Setup the local clock events for a CPU.
+ */
+void __cpuinit local_timer_setup(unsigned int cpu)
+{
+       struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
+       unsigned long flags;
 
-       /* Add on our offset to get the load value */
-       load = (load + offset) % (mpcore_timer_rate / HZ);
+       twd_calibrate_rate(cpu);
 
-       __raw_writel(load, base + TWD_TIMER_COUNTER);
+       clk->name               = "local_timer";
+       clk->features           = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+       clk->rating             = 350;
+       clk->set_mode           = local_timer_set_mode;
+       clk->set_next_event     = local_timer_set_next_event;
+       clk->irq                = IRQ_LOCALTIMER;
+       clk->cpumask            = cpumask_of_cpu(cpu);
+       clk->shift              = 20;
+       clk->mult               = div_sc(mpcore_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 */
-       __raw_writel(1 << IRQ_LOCALTIMER,
-                    __io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET);
+       local_irq_save(flags);
+       get_irq_chip(IRQ_LOCALTIMER)->unmask(IRQ_LOCALTIMER);
+       local_irq_restore(flags);
+
+       clockevents_register_device(clk);
 }
 
 /*
index 131d5b40e072934e2b3cd6a0477f5f6fdfe121da..e521b70713c8cff2f14cd90c00e1b39287291183 100644 (file)
@@ -1,7 +1,7 @@
 #ifndef __ASM_HARDWARE_TWD_H
 #define __ASM_HARDWARE_TWD_H
 
-#define TWD_TIMER_LOAD                 0x00
+#define TWD_TIMER_LOAD                         0x00
 #define TWD_TIMER_COUNTER              0x04
 #define TWD_TIMER_CONTROL              0x08
 #define TWD_TIMER_INTSTAT              0x0C
@@ -13,4 +13,9 @@
 #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)
+
 #endif