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/cnt32_to_63.h>
  17 #include <linux/timer.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irq.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) and a maximum value of 834 days.
  48  *
  49  * Because the hardware timer period is quite short (21 secs if
  50  * 200MHz TCLK) and because cnt32_to_63() needs to be called at
  51  * least once per half period to work properly, a kernel timer is
  52  * set up to ensure this requirement is always met.
  53  */
  54 #define TCLK2NS_SCALE_FACTOR 8
  55
  56 static unsigned long tclk2ns_scale;
  57
  58 unsigned long long sched_clock(void)
  59 {
  60         unsigned long long v = cnt32_to_63(0xffffffff - readl(TIMER0_VAL));
  61         return (v * tclk2ns_scale) >> TCLK2NS_SCALE_FACTOR;
  62 }
  63
  64 static struct timer_list cnt32_to_63_keepwarm_timer;
  65
  66 static void cnt32_to_63_keepwarm(unsigned long data)
  67 {
  68         mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
  69         (void) sched_clock();
  70 }
  71
  72 static void __init setup_sched_clock(unsigned long tclk)
  73 {
  74         unsigned long long v;
  75         unsigned long data;
  76
  77         v = NSEC_PER_SEC;
  78         v <<= TCLK2NS_SCALE_FACTOR;
  79         v += tclk/2;
  80         do_div(v, tclk);
  81         /*
  82          * We want an even value to automatically clear the top bit
  83          * returned by cnt32_to_63() without an additional run time
  84          * instruction. So if the LSB is 1 then round it up.
  85          */
  86         if (v & 1)
  87                 v++;
  88         tclk2ns_scale = v;
  89
  90         data = (0xffffffffUL / tclk / 2 - 2) * HZ;
  91         setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
  92         mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
  93 }
  94
  95 /*
  96  * Clocksource handling.
  97  */
  98 static cycle_t orion_clksrc_read(struct clocksource *cs)
  99 {
 100         return 0xffffffff - readl(TIMER0_VAL);
 101 }
 102
 103 static struct clocksource orion_clksrc = {
 104         .name           = "orion_clocksource",
 105         .shift          = 20,
 106         .rating         = 300,
 107         .read           = orion_clksrc_read,
 108         .mask           = CLOCKSOURCE_MASK(32),
 109         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 110 };
 111
 112
 113
 114 /*
 115  * Clockevent handling.
 116  */
 117 static int
 118 orion_clkevt_next_event(unsigned long delta, struct clock_event_device *dev)
 119 {
 120         unsigned long flags;
 121         u32 u;
 122
 123         if (delta == 0)
 124                 return -ETIME;
 125
 126         local_irq_save(flags);
 127
 128         /*
 129          * Clear and enable clockevent timer interrupt.
 130          */
 131         writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 132
 133         u = readl(BRIDGE_MASK);
 134         u |= BRIDGE_INT_TIMER1;
 135         writel(u, BRIDGE_MASK);
 136
 137         /*
 138          * Setup new clockevent timer value.
 139          */
 140         writel(delta, TIMER1_VAL);
 141
 142         /*
 143          * Enable the timer.
 144          */
 145         u = readl(TIMER_CTRL);
 146         u = (u & ~TIMER1_RELOAD_EN) | TIMER1_EN;
 147         writel(u, TIMER_CTRL);
 148
 149         local_irq_restore(flags);
 150
 151         return 0;
 152 }
 153
 154 static void
 155 orion_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
 156 {
 157         unsigned long flags;
 158         u32 u;
 159
 160         local_irq_save(flags);
 161         if (mode == CLOCK_EVT_MODE_PERIODIC) {
 162                 /*
 163                  * Setup timer to fire at 1/HZ intervals.
 164                  */
 165                 writel(ticks_per_jiffy - 1, TIMER1_RELOAD);
 166                 writel(ticks_per_jiffy - 1, TIMER1_VAL);
 167
 168                 /*
 169                  * Enable timer interrupt.
 170                  */
 171                 u = readl(BRIDGE_MASK);
 172                 writel(u | BRIDGE_INT_TIMER1, BRIDGE_MASK);
 173
 174                 /*
 175                  * Enable timer.
 176                  */
 177                 u = readl(TIMER_CTRL);
 178                 writel(u | TIMER1_EN | TIMER1_RELOAD_EN, TIMER_CTRL);
 179         } else {
 180                 /*
 181                  * Disable timer.
 182                  */
 183                 u = readl(TIMER_CTRL);
 184                 writel(u & ~TIMER1_EN, TIMER_CTRL);
 185
 186                 /*
 187                  * Disable timer interrupt.
 188                  */
 189                 u = readl(BRIDGE_MASK);
 190                 writel(u & ~BRIDGE_INT_TIMER1, BRIDGE_MASK);
 191
 192                 /*
 193                  * ACK pending timer interrupt.
 194                  */
 195                 writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 196
 197         }
 198         local_irq_restore(flags);
 199 }
 200
 201 static struct clock_event_device orion_clkevt = {
 202         .name           = "orion_tick",
 203         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
 204         .shift          = 32,
 205         .rating         = 300,
 206         .set_next_event = orion_clkevt_next_event,
 207         .set_mode       = orion_clkevt_mode,
 208 };
 209
 210 static irqreturn_t orion_timer_interrupt(int irq, void *dev_id)
 211 {
 212         /*
 213          * ACK timer interrupt and call event handler.
 214          */
 215         writel(BRIDGE_INT_TIMER1_CLR, BRIDGE_CAUSE);
 216         orion_clkevt.event_handler(&orion_clkevt);
 217
 218         return IRQ_HANDLED;
 219 }
 220
 221 static struct irqaction orion_timer_irq = {
 222         .name           = "orion_tick",
 223         .flags          = IRQF_DISABLED | IRQF_TIMER,
 224         .handler        = orion_timer_interrupt
 225 };
 226
 227 void __init orion_time_init(unsigned int irq, unsigned int tclk)
 228 {
 229         u32 u;
 230
 231         ticks_per_jiffy = (tclk + HZ/2) / HZ;
 232
 233         /*
 234          * Set scale and timer for sched_clock
 235          */
 236         setup_sched_clock(tclk);
 237
 238         /*
 239          * Setup free-running clocksource timer (interrupts
 240          * disabled.)
 241          */
 242         writel(0xffffffff, TIMER0_VAL);
 243         writel(0xffffffff, TIMER0_RELOAD);
 244         u = readl(BRIDGE_MASK);
 245         writel(u & ~BRIDGE_INT_TIMER0, BRIDGE_MASK);
 246         u = readl(TIMER_CTRL);
 247         writel(u | TIMER0_EN | TIMER0_RELOAD_EN, TIMER_CTRL);
 248         orion_clksrc.mult = clocksource_hz2mult(tclk, orion_clksrc.shift);
 249         clocksource_register(&orion_clksrc);
 250
 251         /*
 252          * Setup clockevent timer (interrupt-driven.)
 253          */
 254         setup_irq(irq, &orion_timer_irq);
 255         orion_clkevt.mult = div_sc(tclk, NSEC_PER_SEC, orion_clkevt.shift);
 256         orion_clkevt.max_delta_ns = clockevent_delta2ns(0xfffffffe, &orion_clkevt);
 257         orion_clkevt.min_delta_ns = clockevent_delta2ns(1, &orion_clkevt);
 258         orion_clkevt.cpumask = cpumask_of(0);
 259         clockevents_register_device(&orion_clkevt);
 260 }