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 #include "timer-of.h"
  28
  29 #define TIMER_IRQ_EN_REG        0x00
  30 #define TIMER_IRQ_EN(val)               BIT(val)
  31 #define TIMER_IRQ_ST_REG        0x04
  32 #define TIMER_CTL_REG(val)      (0x10 * val + 0x10)
  33 #define TIMER_CTL_ENABLE                BIT(0)
  34 #define TIMER_CTL_RELOAD                BIT(1)
  35 #define TIMER_CTL_CLK_SRC(val)          (((val) & 0x3) << 2)
  36 #define TIMER_CTL_CLK_SRC_OSC24M                (1)
  37 #define TIMER_CTL_CLK_PRES(val)         (((val) & 0x7) << 4)
  38 #define TIMER_CTL_ONESHOT               BIT(7)
  39 #define TIMER_INTVAL_REG(val)   (0x10 * (val) + 0x14)
  40 #define TIMER_CNTVAL_REG(val)   (0x10 * (val) + 0x18)
  41
  42 #define TIMER_SYNC_TICKS        3
  43
  44 /*
  45  * When we disable a timer, we need to wait at least for 2 cycles of
  46  * the timer source clock. We will use for that the clocksource timer
  47  * that is already setup and runs at the same frequency than the other
  48  * timers, and we never will be disabled.
  49  */
  50 static void sun4i_clkevt_sync(void __iomem *base)
  51 {
  52         u32 old = readl(base + TIMER_CNTVAL_REG(1));
  53
  54         while ((old - readl(base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
  55                 cpu_relax();
  56 }
  57
  58 static void sun4i_clkevt_time_stop(void __iomem *base, u8 timer)
  59 {
  60         u32 val = readl(base + TIMER_CTL_REG(timer));
  61         writel(val & ~TIMER_CTL_ENABLE, base + TIMER_CTL_REG(timer));
  62         sun4i_clkevt_sync(base);
  63 }
  64
  65 static void sun4i_clkevt_time_setup(void __iomem *base, u8 timer,
  66                                     unsigned long delay)
  67 {
  68         writel(delay, base + TIMER_INTVAL_REG(timer));
  69 }
  70
  71 static void sun4i_clkevt_time_start(void __iomem *base, u8 timer,
  72                                     bool periodic)
  73 {
  74         u32 val = readl(base + TIMER_CTL_REG(timer));
  75
  76         if (periodic)
  77                 val &= ~TIMER_CTL_ONESHOT;
  78         else
  79                 val |= TIMER_CTL_ONESHOT;
  80
  81         writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
  82                base + TIMER_CTL_REG(timer));
  83 }
  84
  85 static int sun4i_clkevt_shutdown(struct clock_event_device *evt)
  86 {
  87         struct timer_of *to = to_timer_of(evt);
  88
  89         sun4i_clkevt_time_stop(timer_of_base(to), 0);
  90
  91         return 0;
  92 }
  93
  94 static int sun4i_clkevt_set_oneshot(struct clock_event_device *evt)
  95 {
  96         struct timer_of *to = to_timer_of(evt);
  97
  98         sun4i_clkevt_time_stop(timer_of_base(to), 0);
  99         sun4i_clkevt_time_start(timer_of_base(to), 0, false);
 100
 101         return 0;
 102 }
 103
 104 static int sun4i_clkevt_set_periodic(struct clock_event_device *evt)
 105 {
 106         struct timer_of *to = to_timer_of(evt);
 107
 108         sun4i_clkevt_time_stop(timer_of_base(to), 0);
 109         sun4i_clkevt_time_setup(timer_of_base(to), 0, timer_of_period(to));
 110         sun4i_clkevt_time_start(timer_of_base(to), 0, true);
 111
 112         return 0;
 113 }
 114
 115 static int sun4i_clkevt_next_event(unsigned long evt,
 116                                    struct clock_event_device *clkevt)
 117 {
 118         struct timer_of *to = to_timer_of(clkevt);
 119
 120         sun4i_clkevt_time_stop(timer_of_base(to), 0);
 121         sun4i_clkevt_time_setup(timer_of_base(to), 0, evt - TIMER_SYNC_TICKS);
 122         sun4i_clkevt_time_start(timer_of_base(to), 0, false);
 123
 124         return 0;
 125 }
 126
 127 static void sun4i_timer_clear_interrupt(void __iomem *base)
 128 {
 129         writel(TIMER_IRQ_EN(0), base + TIMER_IRQ_ST_REG);
 130 }
 131
 132 static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
 133 {
 134         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
 135         struct timer_of *to = to_timer_of(evt);
 136
 137         sun4i_timer_clear_interrupt(timer_of_base(to));
 138         evt->event_handler(evt);
 139
 140         return IRQ_HANDLED;
 141 }
 142
 143 static struct timer_of to = {
 144         .flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
 145
 146         .clkevt = {
 147                 .name = "sun4i_tick",
 148                 .rating = 350,
 149                 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 150                 .set_state_shutdown = sun4i_clkevt_shutdown,
 151                 .set_state_periodic = sun4i_clkevt_set_periodic,
 152                 .set_state_oneshot = sun4i_clkevt_set_oneshot,
 153                 .tick_resume = sun4i_clkevt_shutdown,
 154                 .set_next_event = sun4i_clkevt_next_event,
 155                 .cpumask = cpu_possible_mask,
 156         },
 157
 158         .of_irq = {
 159                 .handler = sun4i_timer_interrupt,
 160                 .flags = IRQF_TIMER | IRQF_IRQPOLL,
 161         },
 162 };
 163
 164 static u64 notrace sun4i_timer_sched_read(void)
 165 {
 166         return ~readl(timer_of_base(&to) + TIMER_CNTVAL_REG(1));
 167 }
 168
 169 static int __init sun4i_timer_init(struct device_node *node)
 170 {
 171         int ret;
 172         u32 val;
 173
 174         ret = timer_of_init(node, &to);
 175         if (ret)
 176                 return ret;
 177
 178         writel(~0, timer_of_base(&to) + TIMER_INTVAL_REG(1));
 179         writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
 180                TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
 181                timer_of_base(&to) + TIMER_CTL_REG(1));
 182
 183         /*
 184          * sched_clock_register does not have priorities, and on sun6i and
 185          * later there is a better sched_clock registered by arm_arch_timer.c
 186          */
 187         if (of_machine_is_compatible("allwinner,sun4i-a10") ||
 188             of_machine_is_compatible("allwinner,sun5i-a13") ||
 189             of_machine_is_compatible("allwinner,sun5i-a10s"))
 190                 sched_clock_register(sun4i_timer_sched_read, 32,
 191                                      timer_of_rate(&to));
 192
 193         ret = clocksource_mmio_init(timer_of_base(&to) + TIMER_CNTVAL_REG(1),
 194                                     node->name, timer_of_rate(&to), 350, 32,
 195                                     clocksource_mmio_readl_down);
 196         if (ret) {
 197                 pr_err("Failed to register clocksource\n");
 198                 return ret;
 199         }
 200
 201         writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
 202                timer_of_base(&to) + TIMER_CTL_REG(0));
 203
 204         /* Make sure timer is stopped before playing with interrupts */
 205         sun4i_clkevt_time_stop(timer_of_base(&to), 0);
 206
 207         /* clear timer0 interrupt */
 208         sun4i_timer_clear_interrupt(timer_of_base(&to));
 209
 210         clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
 211                                         TIMER_SYNC_TICKS, 0xffffffff);
 212
 213         /* Enable timer0 interrupt */
 214         val = readl(timer_of_base(&to) + TIMER_IRQ_EN_REG);
 215         writel(val | TIMER_IRQ_EN(0), timer_of_base(&to) + TIMER_IRQ_EN_REG);
 216
 217         return ret;
 218 }
 219 TIMER_OF_DECLARE(sun4i, "allwinner,sun4i-a10-timer",
 220                        sun4i_timer_init);