drivers/clocksource/timer-prima2.c

   1 /*
   2  * System timer for CSR SiRFprimaII
   3  *
   4  * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
   5  *
   6  * Licensed under GPLv2 or later.
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/clocksource.h>
  13 #include <linux/bitops.h>
  14 #include <linux/irq.h>
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17 #include <linux/slab.h>
  18 #include <linux/of.h>
  19 #include <linux/of_irq.h>
  20 #include <linux/of_address.h>
  21 #include <linux/sched_clock.h>
  22
  23 #define PRIMA2_CLOCK_FREQ 1000000
  24
  25 #define SIRFSOC_TIMER_COUNTER_LO        0x0000
  26 #define SIRFSOC_TIMER_COUNTER_HI        0x0004
  27 #define SIRFSOC_TIMER_MATCH_0           0x0008
  28 #define SIRFSOC_TIMER_MATCH_1           0x000C
  29 #define SIRFSOC_TIMER_MATCH_2           0x0010
  30 #define SIRFSOC_TIMER_MATCH_3           0x0014
  31 #define SIRFSOC_TIMER_MATCH_4           0x0018
  32 #define SIRFSOC_TIMER_MATCH_5           0x001C
  33 #define SIRFSOC_TIMER_STATUS            0x0020
  34 #define SIRFSOC_TIMER_INT_EN            0x0024
  35 #define SIRFSOC_TIMER_WATCHDOG_EN       0x0028
  36 #define SIRFSOC_TIMER_DIV               0x002C
  37 #define SIRFSOC_TIMER_LATCH             0x0030
  38 #define SIRFSOC_TIMER_LATCHED_LO        0x0034
  39 #define SIRFSOC_TIMER_LATCHED_HI        0x0038
  40
  41 #define SIRFSOC_TIMER_WDT_INDEX         5
  42
  43 #define SIRFSOC_TIMER_LATCH_BIT  BIT(0)
  44
  45 #define SIRFSOC_TIMER_REG_CNT 11
  46
  47 static const u32 sirfsoc_timer_reg_list[SIRFSOC_TIMER_REG_CNT] = {
  48         SIRFSOC_TIMER_MATCH_0, SIRFSOC_TIMER_MATCH_1, SIRFSOC_TIMER_MATCH_2,
  49         SIRFSOC_TIMER_MATCH_3, SIRFSOC_TIMER_MATCH_4, SIRFSOC_TIMER_MATCH_5,
  50         SIRFSOC_TIMER_INT_EN, SIRFSOC_TIMER_WATCHDOG_EN, SIRFSOC_TIMER_DIV,
  51         SIRFSOC_TIMER_LATCHED_LO, SIRFSOC_TIMER_LATCHED_HI,
  52 };
  53
  54 static u32 sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT];
  55
  56 static void __iomem *sirfsoc_timer_base;
  57
  58 /* timer0 interrupt handler */
  59 static irqreturn_t sirfsoc_timer_interrupt(int irq, void *dev_id)
  60 {
  61         struct clock_event_device *ce = dev_id;
  62
  63         WARN_ON(!(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_STATUS) &
  64                 BIT(0)));
  65
  66         /* clear timer0 interrupt */
  67         writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
  68
  69         ce->event_handler(ce);
  70
  71         return IRQ_HANDLED;
  72 }
  73
  74 /* read 64-bit timer counter */
  75 static u64 notrace sirfsoc_timer_read(struct clocksource *cs)
  76 {
  77         u64 cycles;
  78
  79         /* latch the 64-bit timer counter */
  80         writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
  81                 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
  82         cycles = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_HI);
  83         cycles = (cycles << 32) |
  84                 readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
  85
  86         return cycles;
  87 }
  88
  89 static int sirfsoc_timer_set_next_event(unsigned long delta,
  90         struct clock_event_device *ce)
  91 {
  92         unsigned long now, next;
  93
  94         writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
  95                 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
  96         now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
  97         next = now + delta;
  98         writel_relaxed(next, sirfsoc_timer_base + SIRFSOC_TIMER_MATCH_0);
  99         writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
 100                 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
 101         now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO);
 102
 103         return next - now > delta ? -ETIME : 0;
 104 }
 105
 106 static int sirfsoc_timer_shutdown(struct clock_event_device *evt)
 107 {
 108         u32 val = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
 109
 110         writel_relaxed(val & ~BIT(0),
 111                        sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
 112         return 0;
 113 }
 114
 115 static int sirfsoc_timer_set_oneshot(struct clock_event_device *evt)
 116 {
 117         u32 val = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
 118
 119         writel_relaxed(val | BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN);
 120         return 0;
 121 }
 122
 123 static void sirfsoc_clocksource_suspend(struct clocksource *cs)
 124 {
 125         int i;
 126
 127         writel_relaxed(SIRFSOC_TIMER_LATCH_BIT,
 128                 sirfsoc_timer_base + SIRFSOC_TIMER_LATCH);
 129
 130         for (i = 0; i < SIRFSOC_TIMER_REG_CNT; i++)
 131                 sirfsoc_timer_reg_val[i] =
 132                         readl_relaxed(sirfsoc_timer_base +
 133                                 sirfsoc_timer_reg_list[i]);
 134 }
 135
 136 static void sirfsoc_clocksource_resume(struct clocksource *cs)
 137 {
 138         int i;
 139
 140         for (i = 0; i < SIRFSOC_TIMER_REG_CNT - 2; i++)
 141                 writel_relaxed(sirfsoc_timer_reg_val[i],
 142                         sirfsoc_timer_base + sirfsoc_timer_reg_list[i]);
 143
 144         writel_relaxed(sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT - 2],
 145                 sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
 146         writel_relaxed(sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT - 1],
 147                 sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
 148 }
 149
 150 static struct clock_event_device sirfsoc_clockevent = {
 151         .name = "sirfsoc_clockevent",
 152         .rating = 200,
 153         .features = CLOCK_EVT_FEAT_ONESHOT,
 154         .set_state_shutdown = sirfsoc_timer_shutdown,
 155         .set_state_oneshot = sirfsoc_timer_set_oneshot,
 156         .set_next_event = sirfsoc_timer_set_next_event,
 157 };
 158
 159 static struct clocksource sirfsoc_clocksource = {
 160         .name = "sirfsoc_clocksource",
 161         .rating = 200,
 162         .mask = CLOCKSOURCE_MASK(64),
 163         .flags = CLOCK_SOURCE_IS_CONTINUOUS,
 164         .read = sirfsoc_timer_read,
 165         .suspend = sirfsoc_clocksource_suspend,
 166         .resume = sirfsoc_clocksource_resume,
 167 };
 168
 169 static struct irqaction sirfsoc_timer_irq = {
 170         .name = "sirfsoc_timer0",
 171         .flags = IRQF_TIMER,
 172         .irq = 0,
 173         .handler = sirfsoc_timer_interrupt,
 174         .dev_id = &sirfsoc_clockevent,
 175 };
 176
 177 /* Overwrite weak default sched_clock with more precise one */
 178 static u64 notrace sirfsoc_read_sched_clock(void)
 179 {
 180         return sirfsoc_timer_read(NULL);
 181 }
 182
 183 static void __init sirfsoc_clockevent_init(void)
 184 {
 185         sirfsoc_clockevent.cpumask = cpumask_of(0);
 186         clockevents_config_and_register(&sirfsoc_clockevent, PRIMA2_CLOCK_FREQ,
 187                                         2, -2);
 188 }
 189
 190 /* initialize the kernel jiffy timer source */
 191 static int __init sirfsoc_prima2_timer_init(struct device_node *np)
 192 {
 193         unsigned long rate;
 194         struct clk *clk;
 195         int ret;
 196
 197         clk = of_clk_get(np, 0);
 198         if (IS_ERR(clk)) {
 199                 pr_err("Failed to get clock");
 200                 return PTR_ERR(clk);
 201         }
 202
 203         ret = clk_prepare_enable(clk);
 204         if (ret) {
 205                 pr_err("Failed to enable clock");
 206                 return ret;
 207         }
 208
 209         rate = clk_get_rate(clk);
 210
 211         if (rate < PRIMA2_CLOCK_FREQ || rate % PRIMA2_CLOCK_FREQ) {
 212                 pr_err("Invalid clock rate");
 213                 return -EINVAL;
 214         }
 215
 216         sirfsoc_timer_base = of_iomap(np, 0);
 217         if (!sirfsoc_timer_base) {
 218                 pr_err("unable to map timer cpu registers\n");
 219                 return -ENXIO;
 220         }
 221
 222         sirfsoc_timer_irq.irq = irq_of_parse_and_map(np, 0);
 223
 224         writel_relaxed(rate / PRIMA2_CLOCK_FREQ / 2 - 1,
 225                 sirfsoc_timer_base + SIRFSOC_TIMER_DIV);
 226         writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
 227         writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
 228         writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
 229
 230         ret = clocksource_register_hz(&sirfsoc_clocksource, PRIMA2_CLOCK_FREQ);
 231         if (ret) {
 232                 pr_err("Failed to register clocksource");
 233                 return ret;
 234         }
 235
 236         sched_clock_register(sirfsoc_read_sched_clock, 64, PRIMA2_CLOCK_FREQ);
 237
 238         ret = setup_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq);
 239         if (ret) {
 240                 pr_err("Failed to setup irq");
 241                 return ret;
 242         }
 243
 244         sirfsoc_clockevent_init();
 245
 246         return 0;
 247 }
 248 CLOCKSOURCE_OF_DECLARE(sirfsoc_prima2_timer,
 249         "sirf,prima2-tick", sirfsoc_prima2_timer_init);