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 #define TIMER_SYNC_TICKS        3
  41
  42 static void __iomem *timer_base;
  43 static u32 ticks_per_jiffy;
  44
  45 /*
  46  * When we disable a timer, we need to wait at least for 2 cycles of
  47  * the timer source clock. We will use for that the clocksource timer
  48  * that is already setup and runs at the same frequency than the other
  49  * timers, and we never will be disabled.
  50  */
  51 static void sun4i_clkevt_sync(void)
  52 {
  53         u32 old = readl(timer_base + TIMER_CNTVAL_REG(1));
  54
  55         while ((old - readl(timer_base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
  56                 cpu_relax();
  57 }
  58
  59 static void sun4i_clkevt_time_stop(u8 timer)
  60 {
  61         u32 val = readl(timer_base + TIMER_CTL_REG(timer));
  62         writel(val & ~TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(timer));
  63         sun4i_clkevt_sync();
  64 }
  65
  66 static void sun4i_clkevt_time_setup(u8 timer, unsigned long delay)
  67 {
  68         writel(delay, timer_base + TIMER_INTVAL_REG(timer));
  69 }
  70
  71 static void sun4i_clkevt_time_start(u8 timer, bool periodic)
  72 {
  73         u32 val = readl(timer_base + TIMER_CTL_REG(timer));
  74
  75         if (periodic)
  76                 val &= ~TIMER_CTL_ONESHOT;
  77         else
  78                 val |= TIMER_CTL_ONESHOT;
  79
  80         writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
  81                timer_base + TIMER_CTL_REG(timer));
  82 }
  83
  84 static int sun4i_clkevt_shutdown(struct clock_event_device *evt)
  85 {
  86         sun4i_clkevt_time_stop(0);
  87         return 0;
  88 }
  89
  90 static int sun4i_clkevt_set_oneshot(struct clock_event_device *evt)
  91 {
  92         sun4i_clkevt_time_stop(0);
  93         sun4i_clkevt_time_start(0, false);
  94         return 0;
  95 }
  96
  97 static int sun4i_clkevt_set_periodic(struct clock_event_device *evt)
  98 {
  99         sun4i_clkevt_time_stop(0);
 100         sun4i_clkevt_time_setup(0, ticks_per_jiffy);
 101         sun4i_clkevt_time_start(0, true);
 102         return 0;
 103 }
 104
 105 static int sun4i_clkevt_next_event(unsigned long evt,
 106                                    struct clock_event_device *unused)
 107 {
 108         sun4i_clkevt_time_stop(0);
 109         sun4i_clkevt_time_setup(0, evt - TIMER_SYNC_TICKS);
 110         sun4i_clkevt_time_start(0, false);
 111
 112         return 0;
 113 }
 114
 115 static struct clock_event_device sun4i_clockevent = {
 116         .name = "sun4i_tick",
 117         .rating = 350,
 118         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 119         .set_state_shutdown = sun4i_clkevt_shutdown,
 120         .set_state_periodic = sun4i_clkevt_set_periodic,
 121         .set_state_oneshot = sun4i_clkevt_set_oneshot,
 122         .tick_resume = sun4i_clkevt_shutdown,
 123         .set_next_event = sun4i_clkevt_next_event,
 124 };
 125
 126 static void sun4i_timer_clear_interrupt(void)
 127 {
 128         writel(TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_ST_REG);
 129 }
 130
 131 static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
 132 {
 133         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
 134
 135         sun4i_timer_clear_interrupt();
 136         evt->event_handler(evt);
 137
 138         return IRQ_HANDLED;
 139 }
 140
 141 static struct irqaction sun4i_timer_irq = {
 142         .name = "sun4i_timer0",
 143         .flags = IRQF_TIMER | IRQF_IRQPOLL,
 144         .handler = sun4i_timer_interrupt,
 145         .dev_id = &sun4i_clockevent,
 146 };
 147
 148 static u64 notrace sun4i_timer_sched_read(void)
 149 {
 150         return ~readl(timer_base + TIMER_CNTVAL_REG(1));
 151 }
 152
 153 static void __init sun4i_timer_init(struct device_node *node)
 154 {
 155         unsigned long rate = 0;
 156         struct clk *clk;
 157         int ret, irq;
 158         u32 val;
 159
 160         timer_base = of_iomap(node, 0);
 161         if (!timer_base)
 162                 panic("Can't map registers");
 163
 164         irq = irq_of_parse_and_map(node, 0);
 165         if (irq <= 0)
 166                 panic("Can't parse IRQ");
 167
 168         clk = of_clk_get(node, 0);
 169         if (IS_ERR(clk))
 170                 panic("Can't get timer clock");
 171         clk_prepare_enable(clk);
 172
 173         rate = clk_get_rate(clk);
 174
 175         writel(~0, timer_base + TIMER_INTVAL_REG(1));
 176         writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
 177                TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
 178                timer_base + TIMER_CTL_REG(1));
 179
 180         /*
 181          * sched_clock_register does not have priorities, and on sun6i and
 182          * later there is a better sched_clock registered by arm_arch_timer.c
 183          */
 184         if (of_machine_is_compatible("allwinner,sun4i-a10") ||
 185             of_machine_is_compatible("allwinner,sun5i-a13") ||
 186             of_machine_is_compatible("allwinner,sun5i-a10s"))
 187                 sched_clock_register(sun4i_timer_sched_read, 32, rate);
 188
 189         clocksource_mmio_init(timer_base + TIMER_CNTVAL_REG(1), node->name,
 190                               rate, 350, 32, clocksource_mmio_readl_down);
 191
 192         ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
 193
 194         writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
 195                timer_base + TIMER_CTL_REG(0));
 196
 197         /* Make sure timer is stopped before playing with interrupts */
 198         sun4i_clkevt_time_stop(0);
 199
 200         /* clear timer0 interrupt */
 201         sun4i_timer_clear_interrupt();
 202
 203         sun4i_clockevent.cpumask = cpu_possible_mask;
 204         sun4i_clockevent.irq = irq;
 205
 206         clockevents_config_and_register(&sun4i_clockevent, rate,
 207                                         TIMER_SYNC_TICKS, 0xffffffff);
 208
 209         ret = setup_irq(irq, &sun4i_timer_irq);
 210         if (ret)
 211                 pr_warn("failed to setup irq %d\n", irq);
 212
 213         /* Enable timer0 interrupt */
 214         val = readl(timer_base + TIMER_IRQ_EN_REG);
 215         writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
 216 }
 217 CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-a10-timer",
 218                        sun4i_timer_init);