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 <blogic@openwrt.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 struct irqaction systick_irqaction = {
  86        .handler = systick_interrupt,
  87        .flags = IRQF_PERCPU | IRQF_TIMER,
  88        .dev_id = &systick.dev,
  89};
  90
  91static int systick_shutdown(struct clock_event_device *evt)
  92{
  93        struct systick_device *sdev;
  94
  95        sdev = container_of(evt, struct systick_device, dev);
  96
  97        if (sdev->irq_requested)
  98                free_irq(systick.dev.irq, &systick_irqaction);
  99        sdev->irq_requested = 0;
 100        iowrite32(0, systick.membase + SYSTICK_CONFIG);
 101
 102        return 0;
 103}
 104
 105static int systick_set_oneshot(struct clock_event_device *evt)
 106{
 107        struct systick_device *sdev;
 108
 109        sdev = container_of(evt, struct systick_device, dev);
 110
 111        if (!sdev->irq_requested)
 112                setup_irq(systick.dev.irq, &systick_irqaction);
 113        sdev->irq_requested = 1;
 114        iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
 115                  systick.membase + SYSTICK_CONFIG);
 116
 117        return 0;
 118}
 119
 120static void __init ralink_systick_init(struct device_node *np)
 121{
 122        systick.membase = of_iomap(np, 0);
 123        if (!systick.membase)
 124                return;
 125
 126        systick_irqaction.name = np->name;
 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.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
 131        systick.dev.irq = irq_of_parse_and_map(np, 0);
 132        if (!systick.dev.irq) {
 133                pr_err("%s: request_irq failed", np->name);
 134                return;
 135        }
 136
 137        clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
 138                        SYSTICK_FREQ, 301, 16, clocksource_mmio_readl_up);
 139
 140        clockevents_register_device(&systick.dev);
 141
 142        pr_info("%s: running - mult: %d, shift: %d\n",
 143                        np->name, systick.dev.mult, systick.dev.shift);
 144}
 145
 146CLOCKSOURCE_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
 147