arch/arm/plat-orion/time.c

   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/sched.h>
  16 #include <linux/timer.h>
  17 #include <linux/clockchips.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/irq.h>
  20 #include <asm/sched_clock.h>
  21 #include <asm/mach/time.h>
  22 #include <mach/bridge-regs.h>
  23 #include <mach/hardware.h>
  24
  25 /*
  26  * Number of timer ticks per jiffy.
  27  */
  28 static u32 ticks_per_jiffy;
  29
  30
  31 /*
  32  * Timer block registers.
  33  */
  34 #define TIMER_CTRL              (TIMER_VIRT_BASE + 0x0000)
  35 #define  TIMER0_EN              0x0001
  36 #define  TIMER0_RELOAD_EN       0x0002
  37 #define  TIMER1_EN              0x0004
  38 #define  TIMER1_RELOAD_EN       0x0008
  39 #define TIMER0_RELOAD           (TIMER_VIRT_BASE + 0x0010)
  40 #define TIMER0_VAL              (TIMER_VIRT_BASE + 0x0014)
  41 #define TIMER1_RELOAD           (TIMER_VIRT_BASE + 0x0018)
  42 #define TIMER1_VAL              (TIMER_VIRT_BASE + 0x001c)
  43
  44
  45 /*
  46  * Orion's sched_clock implementation. It has a resolution of
  47  * at least 7.5ns (133MHz TCLK).
  48  */
  49 static DEFINE_CLOCK_DATA(cd);
  50
  51 unsigned long long notrace sched_clock(void)
  52 {
  53         u32 cyc = 0xffffffff - readl(TIMER0_VAL);
  54         return cyc_to_sched_clock(&cd, cyc, (u32)~0);
  55 }
  56
  57
  58 static void notrace orion_update_sched_clock(void)
  59 {
  60         u32 cyc = 0xffffffff - readl(TIMER0_VAL);
  61         update_sched_clock(&cd, cyc, (u32)~0);
  62 }
  63
  64 static void __init setup_sched_clock(unsigned long tclk)
  65 {
  66         init_sched_clock(&cd, orion_update_sched_clock, 32, tclk);
  67 }
  68
  69 /*
  70  * Clocksource handling.
  71  */
  72 static cycle_t orion_clksrc_read(struct clocksource *cs)
  73 {
  74         return 0xffffffff - readl(TIMER0_VAL);
  75 }
  76
  77 static struct clocksource orion_clksrc = {
  78         .name           = "orion_clocksource",
  79         .rating         = 300,
  80         .read           = orion_clksrc_read,
  81         .mask           = CLOCKSOURCE_MASK(32),
  82         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  83 };
  84
  85
  86
  87 /*
  88  * Clockevent handling.
  89  */
  90 static int
  91 orion_clkevt_next_event(unsigned long delta, struct clock_event_device *dev)
  92 {
  93         unsigned long flags;
  94         u32 u;
  95
  96         if (delta == 0)
  97                 return -ETIME;
  98
  99         local_irq_save(flags);
 100
 101         /*
 102          * Clear and enable clockevent timer interrupt.
 103          */
 104         writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 105
 106         u = readl(BRIDGE_MASK);
 107         u |= BRIDGE_INT_TIMER1;
 108         writel(u, BRIDGE_MASK);
 109
 110         /*
 111          * Setup new clockevent timer value.
 112          */
 113         writel(delta, TIMER1_VAL);
 114
 115         /*
 116          * Enable the timer.
 117          */
 118         u = readl(TIMER_CTRL);
 119         u = (u & ~TIMER1_RELOAD_EN) | TIMER1_EN;
 120         writel(u, TIMER_CTRL);
 121
 122         local_irq_restore(flags);
 123
 124         return 0;
 125 }
 126
 127 static void
 128 orion_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
 129 {
 130         unsigned long flags;
 131         u32 u;
 132
 133         local_irq_save(flags);
 134         if (mode == CLOCK_EVT_MODE_PERIODIC) {
 135                 /*
 136                  * Setup timer to fire at 1/HZ intervals.
 137                  */
 138                 writel(ticks_per_jiffy - 1, TIMER1_RELOAD);
 139                 writel(ticks_per_jiffy - 1, TIMER1_VAL);
 140
 141                 /*
 142                  * Enable timer interrupt.
 143                  */
 144                 u = readl(BRIDGE_MASK);
 145                 writel(u | BRIDGE_INT_TIMER1, BRIDGE_MASK);
 146
 147                 /*
 148                  * Enable timer.
 149                  */
 150                 u = readl(TIMER_CTRL);
 151                 writel(u | TIMER1_EN | TIMER1_RELOAD_EN, TIMER_CTRL);
 152         } else {
 153                 /*
 154                  * Disable timer.
 155                  */
 156                 u = readl(TIMER_CTRL);
 157                 writel(u & ~TIMER1_EN, TIMER_CTRL);
 158
 159                 /*
 160                  * Disable timer interrupt.
 161                  */
 162                 u = readl(BRIDGE_MASK);
 163                 writel(u & ~BRIDGE_INT_TIMER1, BRIDGE_MASK);
 164
 165                 /*
 166                  * ACK pending timer interrupt.
 167                  */
 168                 writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 169
 170         }
 171         local_irq_restore(flags);
 172 }
 173
 174 static struct clock_event_device orion_clkevt = {
 175         .name           = "orion_tick",
 176         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
 177         .shift          = 32,
 178         .rating         = 300,
 179         .set_next_event = orion_clkevt_next_event,
 180         .set_mode       = orion_clkevt_mode,
 181 };
 182
 183 static irqreturn_t orion_timer_interrupt(int irq, void *dev_id)
 184 {
 185         /*
 186          * ACK timer interrupt and call event handler.
 187          */
 188         writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 189         orion_clkevt.event_handler(&orion_clkevt);
 190
 191         return IRQ_HANDLED;
 192 }
 193
 194 static struct irqaction orion_timer_irq = {
 195         .name           = "orion_tick",
 196         .flags          = IRQF_DISABLED | IRQF_TIMER,
 197         .handler        = orion_timer_interrupt
 198 };
 199
 200 void __init orion_time_init(unsigned int irq, unsigned int tclk)
 201 {
 202         u32 u;
 203
 204         ticks_per_jiffy = (tclk + HZ/2) / HZ;
 205
 206         /*
 207          * Set scale and timer for sched_clock
 208          */
 209         setup_sched_clock(tclk);
 210
 211         /*
 212          * Setup free-running clocksource timer (interrupts
 213          * disabled.)
 214          */
 215         writel(0xffffffff, TIMER0_VAL);
 216         writel(0xffffffff, TIMER0_RELOAD);
 217         u = readl(BRIDGE_MASK);
 218         writel(u & ~BRIDGE_INT_TIMER0, BRIDGE_MASK);
 219         u = readl(TIMER_CTRL);
 220         writel(u | TIMER0_EN | TIMER0_RELOAD_EN, TIMER_CTRL);
 221         clocksource_register_hz(&orion_clksrc, tclk);
 222
 223         /*
 224          * Setup clockevent timer (interrupt-driven.)
 225          */
 226         setup_irq(irq, &orion_timer_irq);
 227         orion_clkevt.mult = div_sc(tclk, NSEC_PER_SEC, orion_clkevt.shift);
 228         orion_clkevt.max_delta_ns = clockevent_delta2ns(0xfffffffe, &orion_clkevt);
 229         orion_clkevt.min_delta_ns = clockevent_delta2ns(1, &orion_clkevt);
 230         orion_clkevt.cpumask = cpumask_of(0);
 231         clockevents_register_device(&orion_clkevt);
 232 }