154 lines
3.8 KiB
C
154 lines
3.8 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2013 by John Crispin <john@phrozen.org>
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*/
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#include <linux/clockchips.h>
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#include <linux/clocksource.h>
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#include <linux/interrupt.h>
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#include <linux/reset.h>
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#include <linux/init.h>
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#include <linux/time.h>
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#include <linux/of.h>
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#include <linux/of_irq.h>
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#include <linux/of_address.h>
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#include <asm/mach-ralink/ralink_regs.h>
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#define SYSTICK_FREQ (50 * 1000)
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#define SYSTICK_CONFIG 0x00
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#define SYSTICK_COMPARE 0x04
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#define SYSTICK_COUNT 0x08
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/* route systick irq to mips irq 7 instead of the r4k-timer */
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#define CFG_EXT_STK_EN 0x2
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/* enable the counter */
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#define CFG_CNT_EN 0x1
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struct systick_device {
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void __iomem *membase;
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struct clock_event_device dev;
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int irq_requested;
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int freq_scale;
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};
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static int systick_set_oneshot(struct clock_event_device *evt);
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static int systick_shutdown(struct clock_event_device *evt);
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static int systick_next_event(unsigned long delta,
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struct clock_event_device *evt)
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{
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struct systick_device *sdev;
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u32 count;
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sdev = container_of(evt, struct systick_device, dev);
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count = ioread32(sdev->membase + SYSTICK_COUNT);
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count = (count + delta) % SYSTICK_FREQ;
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iowrite32(count, sdev->membase + SYSTICK_COMPARE);
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return 0;
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}
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static void systick_event_handler(struct clock_event_device *dev)
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{
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/* noting to do here */
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}
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static irqreturn_t systick_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *dev = (struct clock_event_device *) dev_id;
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dev->event_handler(dev);
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return IRQ_HANDLED;
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}
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static struct systick_device systick = {
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.dev = {
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/*
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* cevt-r4k uses 300, make sure systick
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* gets used if available
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*/
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.rating = 310,
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.features = CLOCK_EVT_FEAT_ONESHOT,
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.set_next_event = systick_next_event,
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.set_state_shutdown = systick_shutdown,
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.set_state_oneshot = systick_set_oneshot,
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.event_handler = systick_event_handler,
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},
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};
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static int systick_shutdown(struct clock_event_device *evt)
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{
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struct systick_device *sdev;
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sdev = container_of(evt, struct systick_device, dev);
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if (sdev->irq_requested)
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free_irq(systick.dev.irq, &systick.dev);
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sdev->irq_requested = 0;
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iowrite32(0, systick.membase + SYSTICK_CONFIG);
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return 0;
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}
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static int systick_set_oneshot(struct clock_event_device *evt)
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{
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const char *name = systick.dev.name;
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struct systick_device *sdev;
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int irq = systick.dev.irq;
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sdev = container_of(evt, struct systick_device, dev);
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if (!sdev->irq_requested) {
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if (request_irq(irq, systick_interrupt,
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IRQF_PERCPU | IRQF_TIMER, name, &systick.dev))
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pr_err("Failed to request irq %d (%s)\n", irq, name);
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}
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sdev->irq_requested = 1;
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iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
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systick.membase + SYSTICK_CONFIG);
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return 0;
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}
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static int __init ralink_systick_init(struct device_node *np)
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{
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int ret;
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systick.membase = of_iomap(np, 0);
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if (!systick.membase)
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return -ENXIO;
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systick.dev.name = np->name;
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clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
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systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
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systick.dev.max_delta_ticks = 0x7fff;
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systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
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systick.dev.min_delta_ticks = 0x3;
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systick.dev.irq = irq_of_parse_and_map(np, 0);
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if (!systick.dev.irq) {
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pr_err("%pOFn: request_irq failed", np);
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return -EINVAL;
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}
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ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
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SYSTICK_FREQ, 301, 16,
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clocksource_mmio_readl_up);
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if (ret)
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return ret;
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clockevents_register_device(&systick.dev);
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pr_info("%pOFn: running - mult: %d, shift: %d\n",
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np, systick.dev.mult, systick.dev.shift);
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return 0;
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}
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TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
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