linux/drivers/clocksource/sun4i_timer.c
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   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
  38static void __iomem *timer_base;
  39
  40static 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
  62static 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
  73static 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
  82static 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
  92static 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
  99static 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}
 147CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer",
 148                       sun4i_timer_init);
 149
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