drivers/clocksource/timer-sun5i.c

   1 /*
   2  * Allwinner SoCs hstimer driver.
   3  *
   4  * Copyright (C) 2013 Maxime Ripard
   5  *
   6  * Maxime Ripard <maxime.ripard@free-electrons.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2.  This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/clockchips.h>
  15 #include <linux/delay.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/irq.h>
  18 #include <linux/irqreturn.h>
  19 #include <linux/sched_clock.h>
  20 #include <linux/of.h>
  21 #include <linux/of_address.h>
  22 #include <linux/of_irq.h>
  23
  24 #define TIMER_IRQ_EN_REG                0x00
  25 #define TIMER_IRQ_EN(val)                       BIT(val)
  26 #define TIMER_IRQ_ST_REG                0x04
  27 #define TIMER_CTL_REG(val)              (0x20 * (val) + 0x10)
  28 #define TIMER_CTL_ENABLE                        BIT(0)
  29 #define TIMER_CTL_RELOAD                        BIT(1)
  30 #define TIMER_CTL_CLK_PRES(val)                 (((val) & 0x7) << 4)
  31 #define TIMER_CTL_ONESHOT                       BIT(7)
  32 #define TIMER_INTVAL_LO_REG(val)        (0x20 * (val) + 0x14)
  33 #define TIMER_INTVAL_HI_REG(val)        (0x20 * (val) + 0x18)
  34 #define TIMER_CNTVAL_LO_REG(val)        (0x20 * (val) + 0x1c)
  35 #define TIMER_CNTVAL_HI_REG(val)        (0x20 * (val) + 0x20)
  36
  37 #define TIMER_SYNC_TICKS        3
  38
  39 static void __iomem *timer_base;
  40 static u32 ticks_per_jiffy;
  41
  42 /*
  43  * When we disable a timer, we need to wait at least for 2 cycles of
  44  * the timer source clock. We will use for that the clocksource timer
  45  * that is already setup and runs at the same frequency than the other
  46  * timers, and we never will be disabled.
  47  */
  48 static void sun5i_clkevt_sync(void)
  49 {
  50         u32 old = readl(timer_base + TIMER_CNTVAL_LO_REG(1));
  51
  52         while ((old - readl(timer_base + TIMER_CNTVAL_LO_REG(1))) < TIMER_SYNC_TICKS)
  53                 cpu_relax();
  54 }
  55
  56 static void sun5i_clkevt_time_stop(u8 timer)
  57 {
  58         u32 val = readl(timer_base + TIMER_CTL_REG(timer));
  59         writel(val & ~TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(timer));
  60
  61         sun5i_clkevt_sync();
  62 }
  63
  64 static void sun5i_clkevt_time_setup(u8 timer, u32 delay)
  65 {
  66         writel(delay, timer_base + TIMER_INTVAL_LO_REG(timer));
  67 }
  68
  69 static void sun5i_clkevt_time_start(u8 timer, bool periodic)
  70 {
  71         u32 val = readl(timer_base + TIMER_CTL_REG(timer));
  72
  73         if (periodic)
  74                 val &= ~TIMER_CTL_ONESHOT;
  75         else
  76                 val |= TIMER_CTL_ONESHOT;
  77
  78         writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
  79                timer_base + TIMER_CTL_REG(timer));
  80 }
  81
  82 static void sun5i_clkevt_mode(enum clock_event_mode mode,
  83                               struct clock_event_device *clk)
  84 {
  85         switch (mode) {
  86         case CLOCK_EVT_MODE_PERIODIC:
  87                 sun5i_clkevt_time_stop(0);
  88                 sun5i_clkevt_time_setup(0, ticks_per_jiffy);
  89                 sun5i_clkevt_time_start(0, true);
  90                 break;
  91         case CLOCK_EVT_MODE_ONESHOT:
  92                 sun5i_clkevt_time_stop(0);
  93                 sun5i_clkevt_time_start(0, false);
  94                 break;
  95         case CLOCK_EVT_MODE_UNUSED:
  96         case CLOCK_EVT_MODE_SHUTDOWN:
  97         default:
  98                 sun5i_clkevt_time_stop(0);
  99                 break;
 100         }
 101 }
 102
 103 static int sun5i_clkevt_next_event(unsigned long evt,
 104                                    struct clock_event_device *unused)
 105 {
 106         sun5i_clkevt_time_stop(0);
 107         sun5i_clkevt_time_setup(0, evt - TIMER_SYNC_TICKS);
 108         sun5i_clkevt_time_start(0, false);
 109
 110         return 0;
 111 }
 112
 113 static struct clock_event_device sun5i_clockevent = {
 114         .name = "sun5i_tick",
 115         .rating = 340,
 116         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 117         .set_mode = sun5i_clkevt_mode,
 118         .set_next_event = sun5i_clkevt_next_event,
 119 };
 120
 121
 122 static irqreturn_t sun5i_timer_interrupt(int irq, void *dev_id)
 123 {
 124         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
 125
 126         writel(0x1, timer_base + TIMER_IRQ_ST_REG);
 127         evt->event_handler(evt);
 128
 129         return IRQ_HANDLED;
 130 }
 131
 132 static struct irqaction sun5i_timer_irq = {
 133         .name = "sun5i_timer0",
 134         .flags = IRQF_TIMER | IRQF_IRQPOLL,
 135         .handler = sun5i_timer_interrupt,
 136         .dev_id = &sun5i_clockevent,
 137 };
 138
 139 static u64 sun5i_timer_sched_read(void)
 140 {
 141         return ~readl(timer_base + TIMER_CNTVAL_LO_REG(1));
 142 }
 143
 144 static void __init sun5i_timer_init(struct device_node *node)
 145 {
 146         unsigned long rate;
 147         struct clk *clk;
 148         int ret, irq;
 149         u32 val;
 150
 151         timer_base = of_iomap(node, 0);
 152         if (!timer_base)
 153                 panic("Can't map registers");
 154
 155         irq = irq_of_parse_and_map(node, 0);
 156         if (irq <= 0)
 157                 panic("Can't parse IRQ");
 158
 159         clk = of_clk_get(node, 0);
 160         if (IS_ERR(clk))
 161                 panic("Can't get timer clock");
 162         clk_prepare_enable(clk);
 163         rate = clk_get_rate(clk);
 164
 165         writel(~0, timer_base + TIMER_INTVAL_LO_REG(1));
 166         writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
 167                timer_base + TIMER_CTL_REG(1));
 168
 169         sched_clock_register(sun5i_timer_sched_read, 32, rate);
 170         clocksource_mmio_init(timer_base + TIMER_CNTVAL_LO_REG(1), node->name,
 171                               rate, 340, 32, clocksource_mmio_readl_down);
 172
 173         ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
 174
 175         ret = setup_irq(irq, &sun5i_timer_irq);
 176         if (ret)
 177                 pr_warn("failed to setup irq %d\n", irq);
 178
 179         /* Enable timer0 interrupt */
 180         val = readl(timer_base + TIMER_IRQ_EN_REG);
 181         writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
 182
 183         sun5i_clockevent.cpumask = cpu_possible_mask;
 184         sun5i_clockevent.irq = irq;
 185
 186         clockevents_config_and_register(&sun5i_clockevent, rate,
 187                                         TIMER_SYNC_TICKS, 0xffffffff);
 188 }
 189 CLOCKSOURCE_OF_DECLARE(sun5i_a13, "allwinner,sun5i-a13-hstimer",
 190                        sun5i_timer_init);
 191 CLOCKSOURCE_OF_DECLARE(sun7i_a20, "allwinner,sun7i-a20-hstimer",
 192                        sun5i_timer_init);