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/of.h>
  23 #include <linux/of_address.h>
  24 #include <linux/of_irq.h>
  25
  26 #define TIMER_IRQ_EN_REG        0x00
  27 #define TIMER_IRQ_EN(val)               (1 << val)
  28 #define TIMER_IRQ_ST_REG        0x04
  29 #define TIMER_CTL_REG(val)      (0x10 * val + 0x10)
  30 #define TIMER_CTL_ENABLE                (1 << 0)
  31 #define TIMER_CTL_AUTORELOAD            (1 << 1)
  32 #define TIMER_CTL_ONESHOT               (1 << 7)
  33 #define TIMER_INTVAL_REG(val)   (0x10 * val + 0x14)
  34 #define TIMER_CNTVAL_REG(val)   (0x10 * val + 0x18)
  35
  36 #define TIMER_SCAL              16
  37
  38 static void __iomem *timer_base;
  39
  40 static void sun4i_clkevt_mode(enum clock_event_mode mode,
  41                               struct clock_event_device *clk)
  42 {
  43         u32 u = readl(timer_base + TIMER_CTL_REG(0));
  44
  45         switch (mode) {
  46         case CLOCK_EVT_MODE_PERIODIC:
  47                 u &= ~(TIMER_CTL_ONESHOT);
  48                 writel(u | TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(0));
  49                 break;
  50
  51         case CLOCK_EVT_MODE_ONESHOT:
  52                 writel(u | TIMER_CTL_ONESHOT, timer_base + TIMER_CTL_REG(0));
  53                 break;
  54         case CLOCK_EVT_MODE_UNUSED:
  55         case CLOCK_EVT_MODE_SHUTDOWN:
  56         default:
  57                 writel(u & ~(TIMER_CTL_ENABLE), timer_base + TIMER_CTL_REG(0));
  58                 break;
  59         }
  60 }
  61
  62 static int sun4i_clkevt_next_event(unsigned long evt,
  63                                    struct clock_event_device *unused)
  64 {
  65         u32 u = readl(timer_base + TIMER_CTL_REG(0));
  66         writel(evt, timer_base + TIMER_CNTVAL_REG(0));
  67         writel(u | TIMER_CTL_ENABLE | TIMER_CTL_AUTORELOAD,
  68                timer_base + TIMER_CTL_REG(0));
  69
  70         return 0;
  71 }
  72
  73 static struct clock_event_device sun4i_clockevent = {
  74         .name = "sun4i_tick",
  75         .rating = 300,
  76         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  77         .set_mode = sun4i_clkevt_mode,
  78         .set_next_event = sun4i_clkevt_next_event,
  79 };
  80
  81
  82 static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
  83 {
  84         struct clock_event_device *evt = (struct clock_event_device *)dev_id;
  85
  86         writel(0x1, timer_base + TIMER_IRQ_ST_REG);
  87         evt->event_handler(evt);
  88
  89         return IRQ_HANDLED;
  90 }
  91
  92 static struct irqaction sun4i_timer_irq = {
  93         .name = "sun4i_timer0",
  94         .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  95         .handler = sun4i_timer_interrupt,
  96         .dev_id = &sun4i_clockevent,
  97 };
  98
  99 static void __init sun4i_timer_init(struct device_node *node)
 100 {
 101         unsigned long rate = 0;
 102         struct clk *clk;
 103         int ret, irq;
 104         u32 val;
 105
 106         timer_base = of_iomap(node, 0);
 107         if (!timer_base)
 108                 panic("Can't map registers");
 109
 110         irq = irq_of_parse_and_map(node, 0);
 111         if (irq <= 0)
 112                 panic("Can't parse IRQ");
 113
 114         clk = of_clk_get(node, 0);
 115         if (IS_ERR(clk))
 116                 panic("Can't get timer clock");
 117
 118         rate = clk_get_rate(clk);
 119
 120         writel(rate / (TIMER_SCAL * HZ),
 121                timer_base + TIMER_INTVAL_REG(0));
 122
 123         /* set clock source to HOSC, 16 pre-division */
 124         val = readl(timer_base + TIMER_CTL_REG(0));
 125         val &= ~(0x07 << 4);
 126         val &= ~(0x03 << 2);
 127         val |= (4 << 4) | (1 << 2);
 128         writel(val, timer_base + TIMER_CTL_REG(0));
 129
 130         /* set mode to auto reload */
 131         val = readl(timer_base + TIMER_CTL_REG(0));
 132         writel(val | TIMER_CTL_AUTORELOAD, timer_base + TIMER_CTL_REG(0));
 133
 134         ret = setup_irq(irq, &sun4i_timer_irq);
 135         if (ret)
 136                 pr_warn("failed to setup irq %d\n", irq);
 137
 138         /* Enable timer0 interrupt */
 139         val = readl(timer_base + TIMER_IRQ_EN_REG);
 140         writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
 141
 142         sun4i_clockevent.cpumask = cpumask_of(0);
 143
 144         clockevents_config_and_register(&sun4i_clockevent, rate / TIMER_SCAL,
 145                                         0x1, 0xff);
 146 }
 147 CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer",
 148                        sun4i_timer_init);