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   1 /*
   2  * arch/arm/plat-orion/time.c
   3  *
   4  * Marvell Orion SoC timer handling.
   5  *
   6  * This file is licensed under the terms of the GNU General Public
   7  * License version 2.  This program is licensed "as is" without any
   8  * warranty of any kind, whether express or implied.
   9  *
  10  * Timer 0 is used as free-running clocksource, while timer 1 is
  11  * used as clock_event_device.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/clockchips.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/irq.h>
  18 #include <asm/mach/time.h>
  19 #include <mach/hardware.h>
  20
  21 /*
  22  * Number of timer ticks per jiffy.
  23  */
  24 static u32 ticks_per_jiffy;
  25
  26
  27 /*
  28  * Timer block registers.
  29  */
  30 #define TIMER_CTRL              (TIMER_VIRT_BASE + 0x0000)
  31 #define  TIMER0_EN              0x0001
  32 #define  TIMER0_RELOAD_EN       0x0002
  33 #define  TIMER1_EN              0x0004
  34 #define  TIMER1_RELOAD_EN       0x0008
  35 #define TIMER0_RELOAD           (TIMER_VIRT_BASE + 0x0010)
  36 #define TIMER0_VAL              (TIMER_VIRT_BASE + 0x0014)
  37 #define TIMER1_RELOAD           (TIMER_VIRT_BASE + 0x0018)
  38 #define TIMER1_VAL              (TIMER_VIRT_BASE + 0x001c)
  39
  40
  41 /*
  42  * Clocksource handling.
  43  */
  44 static cycle_t orion_clksrc_read(void)
  45 {
  46         return 0xffffffff - readl(TIMER0_VAL);
  47 }
  48
  49 static struct clocksource orion_clksrc = {
  50         .name           = "orion_clocksource",
  51         .shift          = 20,
  52         .rating         = 300,
  53         .read           = orion_clksrc_read,
  54         .mask           = CLOCKSOURCE_MASK(32),
  55         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  56 };
  57
  58
  59
  60 /*
  61  * Clockevent handling.
  62  */
  63 static int
  64 orion_clkevt_next_event(unsigned long delta, struct clock_event_device *dev)
  65 {
  66         unsigned long flags;
  67         u32 u;
  68
  69         if (delta == 0)
  70                 return -ETIME;
  71
  72         local_irq_save(flags);
  73
  74         /*
  75          * Clear and enable clockevent timer interrupt.
  76          */
  77         writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
  78
  79         u = readl(BRIDGE_MASK);
  80         u |= BRIDGE_INT_TIMER1;
  81         writel(u, BRIDGE_MASK);
  82
  83         /*
  84          * Setup new clockevent timer value.
  85          */
  86         writel(delta, TIMER1_VAL);
  87
  88         /*
  89          * Enable the timer.
  90          */
  91         u = readl(TIMER_CTRL);
  92         u = (u & ~TIMER1_RELOAD_EN) | TIMER1_EN;
  93         writel(u, TIMER_CTRL);
  94
  95         local_irq_restore(flags);
  96
  97         return 0;
  98 }
  99
 100 static void
 101 orion_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
 102 {
 103         unsigned long flags;
 104         u32 u;
 105
 106         local_irq_save(flags);
 107         if (mode == CLOCK_EVT_MODE_PERIODIC) {
 108                 /*
 109                  * Setup timer to fire at 1/HZ intervals.
 110                  */
 111                 writel(ticks_per_jiffy - 1, TIMER1_RELOAD);
 112                 writel(ticks_per_jiffy - 1, TIMER1_VAL);
 113
 114                 /*
 115                  * Enable timer interrupt.
 116                  */
 117                 u = readl(BRIDGE_MASK);
 118                 writel(u | BRIDGE_INT_TIMER1, BRIDGE_MASK);
 119
 120                 /*
 121                  * Enable timer.
 122                  */
 123                 u = readl(TIMER_CTRL);
 124                 writel(u | TIMER1_EN | TIMER1_RELOAD_EN, TIMER_CTRL);
 125         } else {
 126                 /*
 127                  * Disable timer.
 128                  */
 129                 u = readl(TIMER_CTRL);
 130                 writel(u & ~TIMER1_EN, TIMER_CTRL);
 131
 132                 /*
 133                  * Disable timer interrupt.
 134                  */
 135                 u = readl(BRIDGE_MASK);
 136                 writel(u & ~BRIDGE_INT_TIMER1, BRIDGE_MASK);
 137
 138                 /*
 139                  * ACK pending timer interrupt.
 140                  */
 141                 writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 142
 143         }
 144         local_irq_restore(flags);
 145 }
 146
 147 static struct clock_event_device orion_clkevt = {
 148         .name           = "orion_tick",
 149         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
 150         .shift          = 32,
 151         .rating         = 300,
 152         .set_next_event = orion_clkevt_next_event,
 153         .set_mode       = orion_clkevt_mode,
 154 };
 155
 156 static irqreturn_t orion_timer_interrupt(int irq, void *dev_id)
 157 {
 158         /*
 159          * ACK timer interrupt and call event handler.
 160          */
 161         writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 162         orion_clkevt.event_handler(&orion_clkevt);
 163
 164         return IRQ_HANDLED;
 165 }
 166
 167 static struct irqaction orion_timer_irq = {
 168         .name           = "orion_tick",
 169         .flags          = IRQF_DISABLED | IRQF_TIMER,
 170         .handler        = orion_timer_interrupt
 171 };
 172
 173 void __init orion_time_init(unsigned int irq, unsigned int tclk)
 174 {
 175         u32 u;
 176
 177         ticks_per_jiffy = (tclk + HZ/2) / HZ;
 178
 179
 180         /*
 181          * Setup free-running clocksource timer (interrupts
 182          * disabled.)
 183          */
 184         writel(0xffffffff, TIMER0_VAL);
 185         writel(0xffffffff, TIMER0_RELOAD);
 186         u = readl(BRIDGE_MASK);
 187         writel(u & ~BRIDGE_INT_TIMER0, BRIDGE_MASK);
 188         u = readl(TIMER_CTRL);
 189         writel(u | TIMER0_EN | TIMER0_RELOAD_EN, TIMER_CTRL);
 190         orion_clksrc.mult = clocksource_hz2mult(tclk, orion_clksrc.shift);
 191         clocksource_register(&orion_clksrc);
 192
 193
 194         /*
 195          * Setup clockevent timer (interrupt-driven.)
 196          */
 197         setup_irq(irq, &orion_timer_irq);
 198         orion_clkevt.mult = div_sc(tclk, NSEC_PER_SEC, orion_clkevt.shift);
 199         orion_clkevt.max_delta_ns = clockevent_delta2ns(0xfffffffe, &orion_clkevt);
 200         orion_clkevt.min_delta_ns = clockevent_delta2ns(1, &orion_clkevt);
 201         orion_clkevt.cpumask = cpumask_of(0);
 202         clockevents_register_device(&orion_clkevt);
 203 }