LXR linux/arch/mips/ralink/cevt-rt3352.c

   1/*
   2 * This file is subject to the terms and conditions of the GNU General Public
   3 * License.  See the file "COPYING" in the main directory of this archive
   4 * for more details.
   5 *
   6 * Copyright (C) 2013 by John Crispin <john@phrozen.org>
   7 */
   8
   9#include <linux/clockchips.h>
  10#include <linux/clocksource.h>
  11#include <linux/interrupt.h>
  12#include <linux/reset.h>
  13#include <linux/init.h>
  14#include <linux/time.h>
  15#include <linux/of.h>
  16#include <linux/of_irq.h>
  17#include <linux/of_address.h>
  18
  19#include <asm/mach-ralink/ralink_regs.h>
  20
  21#define SYSTICK_FREQ            (50 * 1000)
  22
  23#define SYSTICK_CONFIG          0x00
  24#define SYSTICK_COMPARE         0x04
  25#define SYSTICK_COUNT           0x08
  26
  27/* route systick irq to mips irq 7 instead of the r4k-timer */
  28#define CFG_EXT_STK_EN          0x2
  29/* enable the counter */
  30#define CFG_CNT_EN              0x1
  31
  32struct systick_device {
  33        void __iomem *membase;
  34        struct clock_event_device dev;
  35        int irq_requested;
  36        int freq_scale;
  37};
  38
  39static int systick_set_oneshot(struct clock_event_device *evt);
  40static int systick_shutdown(struct clock_event_device *evt);
  41
  42static int systick_next_event(unsigned long delta,
  43                                struct clock_event_device *evt)
  44{
  45        struct systick_device *sdev;
  46        u32 count;
  47
  48        sdev = container_of(evt, struct systick_device, dev);
  49        count = ioread32(sdev->membase + SYSTICK_COUNT);
  50        count = (count + delta) % SYSTICK_FREQ;
  51        iowrite32(count, sdev->membase + SYSTICK_COMPARE);
  52
  53        return 0;
  54}
  55
  56static void systick_event_handler(struct clock_event_device *dev)
  57{
  58        /* noting to do here */
  59}
  60
  61static irqreturn_t systick_interrupt(int irq, void *dev_id)
  62{
  63        struct clock_event_device *dev = (struct clock_event_device *) dev_id;
  64
  65        dev->event_handler(dev);
  66
  67        return IRQ_HANDLED;
  68}
  69
  70static struct systick_device systick = {
  71        .dev = {
  72                /*
  73                 * cevt-r4k uses 300, make sure systick
  74                 * gets used if available
  75                 */
  76                .rating                 = 310,
  77                .features               = CLOCK_EVT_FEAT_ONESHOT,
  78                .set_next_event         = systick_next_event,
  79                .set_state_shutdown     = systick_shutdown,
  80                .set_state_oneshot      = systick_set_oneshot,
  81                .event_handler          = systick_event_handler,
  82        },
  83};
  84
  85static int systick_shutdown(struct clock_event_device *evt)
  86{
  87        struct systick_device *sdev;
  88
  89        sdev = container_of(evt, struct systick_device, dev);
  90
  91        if (sdev->irq_requested)
  92                free_irq(systick.dev.irq, &systick.dev);
  93        sdev->irq_requested = 0;
  94        iowrite32(0, systick.membase + SYSTICK_CONFIG);
  95
  96        return 0;
  97}
  98
  99static int systick_set_oneshot(struct clock_event_device *evt)
 100{
 101        const char *name = systick.dev.name;
 102        struct systick_device *sdev;
 103        int irq = systick.dev.irq;
 104
 105        sdev = container_of(evt, struct systick_device, dev);
 106
 107        if (!sdev->irq_requested) {
 108                if (request_irq(irq, systick_interrupt,
 109                                IRQF_PERCPU | IRQF_TIMER, name, &systick.dev))
 110                        pr_err("Failed to request irq %d (%s)\n", irq, name);
 111        }
 112        sdev->irq_requested = 1;
 113        iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
 114                  systick.membase + SYSTICK_CONFIG);
 115
 116        return 0;
 117}
 118
 119static int __init ralink_systick_init(struct device_node *np)
 120{
 121        int ret;
 122
 123        systick.membase = of_iomap(np, 0);
 124        if (!systick.membase)
 125                return -ENXIO;
 126
 127        systick.dev.name = np->name;
 128        clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
 129        systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
 130        systick.dev.max_delta_ticks = 0x7fff;
 131        systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
 132        systick.dev.min_delta_ticks = 0x3;
 133        systick.dev.irq = irq_of_parse_and_map(np, 0);
 134        if (!systick.dev.irq) {
 135                pr_err("%pOFn: request_irq failed", np);
 136                return -EINVAL;
 137        }
 138
 139        ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
 140                                    SYSTICK_FREQ, 301, 16,
 141                                    clocksource_mmio_readl_up);
 142        if (ret)
 143                return ret;
 144
 145        clockevents_register_device(&systick.dev);
 146
 147        pr_info("%pOFn: running - mult: %d, shift: %d\n",
 148                        np, systick.dev.mult, systick.dev.shift);
 149
 150        return 0;
 151}
 152
 153TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
 154