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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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3.9 kB · 157 lines
C
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158// SPDX-License-Identifier: GPL-2.0/* * Ralink System Tick Counter driver present on RT3352 and MT7620 SoCs. * * Copyright (C) 2013 by John Crispin <john@phrozen.org> */
#include <linux/clockchips.h>#include <linux/clocksource.h>#include <linux/interrupt.h>#include <linux/reset.h>#include <linux/init.h>#include <linux/time.h>#include <linux/of.h>#include <linux/of_irq.h>#include <linux/of_address.h>
#define SYSTICK_FREQ (50 * 1000)
#define SYSTICK_CONFIG 0x00#define SYSTICK_COMPARE 0x04#define SYSTICK_COUNT 0x08
/* route systick irq to mips irq 7 instead of the r4k-timer */#define CFG_EXT_STK_EN 0x2/* enable the counter */#define CFG_CNT_EN 0x1
struct systick_device { void __iomem *membase; struct clock_event_device dev; int irq_requested; int freq_scale;};
static int systick_set_oneshot(struct clock_event_device *evt);static int systick_shutdown(struct clock_event_device *evt);
static int systick_next_event(unsigned long delta, struct clock_event_device *evt){ struct systick_device *sdev; u32 count;
sdev = container_of(evt, struct systick_device, dev); count = ioread32(sdev->membase + SYSTICK_COUNT); count = (count + delta) % SYSTICK_FREQ; iowrite32(count, sdev->membase + SYSTICK_COMPARE);
return 0;}
static void systick_event_handler(struct clock_event_device *dev){ /* noting to do here */}
static irqreturn_t systick_interrupt(int irq, void *dev_id){ struct clock_event_device *dev = (struct clock_event_device *)dev_id;
dev->event_handler(dev);
return IRQ_HANDLED;}
static struct systick_device systick = { .dev = { /* * cevt-r4k uses 300, make sure systick * gets used if available */ .rating = 310, .features = CLOCK_EVT_FEAT_ONESHOT, .set_next_event = systick_next_event, .set_state_shutdown = systick_shutdown, .set_state_oneshot = systick_set_oneshot, .event_handler = systick_event_handler, },};
static int systick_shutdown(struct clock_event_device *evt){ struct systick_device *sdev;
sdev = container_of(evt, struct systick_device, dev);
if (sdev->irq_requested) free_irq(systick.dev.irq, &systick.dev); sdev->irq_requested = 0; iowrite32(0, systick.membase + SYSTICK_CONFIG);
return 0;}
static int systick_set_oneshot(struct clock_event_device *evt){ const char *name = systick.dev.name; struct systick_device *sdev; int irq = systick.dev.irq;
sdev = container_of(evt, struct systick_device, dev);
if (!sdev->irq_requested) { if (request_irq(irq, systick_interrupt, IRQF_PERCPU | IRQF_TIMER, name, &systick.dev)) pr_err("Failed to request irq %d (%s)\n", irq, name); } sdev->irq_requested = 1; iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN, systick.membase + SYSTICK_CONFIG);
return 0;}
static int __init ralink_systick_init(struct device_node *np){ int ret;
systick.membase = of_iomap(np, 0); if (!systick.membase) return -ENXIO;
systick.dev.name = np->name; clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60); systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev); systick.dev.max_delta_ticks = 0x7fff; systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev); systick.dev.min_delta_ticks = 0x3; systick.dev.irq = irq_of_parse_and_map(np, 0); if (!systick.dev.irq) { pr_err("%pOFn: request_irq failed", np); ret = -EINVAL; goto err_iounmap; }
ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name, SYSTICK_FREQ, 301, 16, clocksource_mmio_readl_up); if (ret) goto err_free_irq;
clockevents_register_device(&systick.dev);
pr_info("%pOFn: running - mult: %d, shift: %d\n", np, systick.dev.mult, systick.dev.shift);
return 0;
err_free_irq: irq_dispose_mapping(systick.dev.irq);err_iounmap: iounmap(systick.membase); return ret;}
TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);