drivers/clocksource/sun4i_timer.c

   1 /*
   2  * Allwinner A1X SoCs timer handling.
   3  *
   4  * Copyright (C) 2012 Maxime Ripard
   5  *
   6  * Maxime Ripard <maxime.ripard@free-electrons.com>
   7  *
   8  * Based on code from
   9  * Allwinner Technology Co., Ltd. <www.allwinnertech.com>
  10  * Benn Huang <benn@allwinnertech.com>
  11  *
  12  * This file is licensed under the terms of the GNU General Public
  13  * License version 2.  This program is licensed "as is" without any
  14  * warranty of any kind, whether express or implied.
  15  */
  16
  17 #include <linux/clk.h>
  18 #include <linux/clockchips.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irq.h>
  21 #include <linux/irqreturn.h>
  22 #include <linux/sched_clock.h>
  23 #include <linux/of.h>
  24 #include <linux/of_address.h>
  25 #include <linux/of_irq.h>
  26
  27 #define TIMER_IRQ_EN_REG        0x00
  28 #define TIMER_IRQ_EN(val)               BIT(val)
  29 #define TIMER_IRQ_ST_REG        0x04
  30 #define TIMER_CTL_REG(val)      (0x10 * val + 0x10)
  31 #define TIMER_CTL_ENABLE                BIT(0)
  32 #define TIMER_CTL_RELOAD                BIT(1)
  33 #define TIMER_CTL_CLK_SRC(val)          (((val) & 0x3) << 2)
  34 #define TIMER_CTL_CLK_SRC_OSC24M                (1)
  35 #define TIMER_CTL_CLK_PRES(val)         (((val) & 0x7) << 4)
  36 #define TIMER_CTL_ONESHOT               BIT(7)
  37 #define TIMER_INTVAL_REG(val)   (0x10 * (val) + 0x14)
  38 #define TIMER_CNTVAL_REG(val)   (0x10 * (val) + 0x18)
  39
  40 static void __iomem *timer_base;
  41 static u32 ticks_per_jiffy;
  42
  43 /*
  44  * When we disable a timer, we need to wait at least for 2 cycles of
  45  * the timer source clock. We will use for that the clocksource timer
  46  * that is already setup and runs at the same frequency than the other
  47  * timers, and we never will be disabled.
  48  */
  49 static void sun4i_clkevt_sync(void)
  50 {
  51         u32 old = readl(timer_base + TIMER_CNTVAL_REG(1));
  52
  53         while ((old - readl(timer_base + TIMER_CNTVAL_REG(1))) < 3)
  54                 cpu_relax();
  55 }
  56
  57 static void sun4i_clkevt_time_stop(u8 timer)
  58 {
  59         u32 val = readl(timer_base + TIMER_CTL_REG(timer));
  60         writel(val & ~TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(timer));
  61         sun4i_clkevt_sync();
  62 }
  63
  64 static void sun4i_clkevt_time_setup(u8 timer, unsigned long delay)
  65 {
  66         writel(delay, timer_base + TIMER_INTVAL_REG(timer));
  67 }
  68
  69 static void sun4i_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 sun4i_clkevt_mode(enum clock_event_mode mode,
  83                               struct clock_event_device *clk)
  84 {
  85         switch (mode) {
  86         case CLOCK_EVT_MODE_PERIODIC:
  87                 sun4i_clkevt_time_stop(0);
  88                 sun4i_clkevt_time_setup(0, ticks_per_jiffy);
  89                 sun4i_clkevt_time_start(0, true);
  90                 break;
  91         case CLOCK_EVT_MODE_ONESHOT:
  92                 sun4i_clkevt_time_stop(0);
  93                 sun4i_clkevt_time_start(0, false);
  94                 break;
  95         case CLOCK_EVT_MODE_UNUSED:
  96         case CLOCK_EVT_MODE_SHUTDOWN:
  97         default:
  98                 sun4i_clkevt_time_stop(0);
  99                 break;
 100         }
 101 }
 102
 103 static int sun4i_clkevt_next_event(unsigned long evt,
 104                                    struct clock_event_device *unused)
 105 {
 106         sun4i_clkevt_time_stop(0);
 107         sun4i_clkevt_time_setup(0, evt);
 108         sun4i_clkevt_time_start(0, false);
 109
 110         return 0;
 111 }
 112
 113 static struct clock_event_device sun4i_clockevent = {
 114         .name = "sun4i_tick",
 115         .rating = 300,
 116         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 117         .set_mode = sun4i_clkevt_mode,
 118         .set_next_event = sun4i_clkevt_next_event,
 119 };
 120
 121 static void sun4i_timer_clear_interrupt(void)
 122 {
 123         writel(TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_ST_REG);
 124 }
 125
 126 static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
 127 {
 128         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
 129
 130         sun4i_timer_clear_interrupt();
 131         evt->event_handler(evt);
 132
 133         return IRQ_HANDLED;
 134 }
 135
 136 static struct irqaction sun4i_timer_irq = {
 137         .name = "sun4i_timer0",
 138         .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 139         .handler = sun4i_timer_interrupt,
 140         .dev_id = &sun4i_clockevent,
 141 };
 142
 143 static u32 sun4i_timer_sched_read(void)
 144 {
 145         return ~readl(timer_base + TIMER_CNTVAL_REG(1));
 146 }
 147
 148 static void __init sun4i_timer_init(struct device_node *node)
 149 {
 150         unsigned long rate = 0;
 151         struct clk *clk;
 152         int ret, irq;
 153         u32 val;
 154
 155         timer_base = of_iomap(node, 0);
 156         if (!timer_base)
 157                 panic("Can't map registers");
 158
 159         irq = irq_of_parse_and_map(node, 0);
 160         if (irq <= 0)
 161                 panic("Can't parse IRQ");
 162
 163         clk = of_clk_get(node, 0);
 164         if (IS_ERR(clk))
 165                 panic("Can't get timer clock");
 166         clk_prepare_enable(clk);
 167
 168         rate = clk_get_rate(clk);
 169
 170         writel(~0, timer_base + TIMER_INTVAL_REG(1));
 171         writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
 172                TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
 173                timer_base + TIMER_CTL_REG(1));
 174
 175         setup_sched_clock(sun4i_timer_sched_read, 32, rate);
 176         clocksource_mmio_init(timer_base + TIMER_CNTVAL_REG(1), node->name,
 177                               rate, 300, 32, clocksource_mmio_readl_down);
 178
 179         ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
 180
 181         writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
 182                timer_base + TIMER_CTL_REG(0));
 183
 184         /* clear timer0 interrupt */
 185         sun4i_timer_clear_interrupt();
 186
 187         sun4i_clockevent.cpumask = cpumask_of(0);
 188
 189         clockevents_config_and_register(&sun4i_clockevent, rate, 0x1,
 190                                         0xffffffff);
 191
 192         ret = setup_irq(irq, &sun4i_timer_irq);
 193         if (ret)
 194                 pr_warn("failed to setup irq %d\n", irq);
 195
 196         /* Enable timer0 interrupt */
 197         val = readl(timer_base + TIMER_IRQ_EN_REG);
 198         writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
 199 }
 200 CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer",
 201                        sun4i_timer_init);