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- /*
- * Copyright (C) 2012 Broadcom Corporation
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation version 2.
- *
- * This program is distributed "as is" WITHOUT ANY WARRANTY of any
- * kind, whether express or implied; without even the implied warranty
- * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- */
- #include <linux/init.h>
- #include <linux/irq.h>
- #include <linux/interrupt.h>
- #include <linux/jiffies.h>
- #include <linux/clockchips.h>
- #include <linux/types.h>
- #include <linux/clk.h>
- #include <linux/io.h>
- #include <asm/mach/time.h>
- #include <linux/of.h>
- #include <linux/of_address.h>
- #include <linux/of_irq.h>
- #define KONA_GPTIMER_STCS_OFFSET 0x00000000
- #define KONA_GPTIMER_STCLO_OFFSET 0x00000004
- #define KONA_GPTIMER_STCHI_OFFSET 0x00000008
- #define KONA_GPTIMER_STCM0_OFFSET 0x0000000C
- #define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 0
- #define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 4
- struct kona_bcm_timers {
- int tmr_irq;
- void __iomem *tmr_regs;
- };
- static struct kona_bcm_timers timers;
- static u32 arch_timer_rate;
- /*
- * We use the peripheral timers for system tick, the cpu global timer for
- * profile tick
- */
- static void kona_timer_disable_and_clear(void __iomem *base)
- {
- uint32_t reg;
- /*
- * clear and disable interrupts
- * We are using compare/match register 0 for our system interrupts
- */
- reg = readl(base + KONA_GPTIMER_STCS_OFFSET);
- /* Clear compare (0) interrupt */
- reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
- /* disable compare */
- reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
- writel(reg, base + KONA_GPTIMER_STCS_OFFSET);
- }
- static void
- kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)
- {
- int loop_limit = 4;
- /*
- * Read 64-bit free running counter
- * 1. Read hi-word
- * 2. Read low-word
- * 3. Read hi-word again
- * 4.1
- * if new hi-word is not equal to previously read hi-word, then
- * start from #1
- * 4.2
- * if new hi-word is equal to previously read hi-word then stop.
- */
- while (--loop_limit) {
- *msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
- *lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
- if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
- break;
- }
- if (!loop_limit) {
- pr_err("bcm_kona_timer: getting counter failed.\n");
- pr_err(" Timer will be impacted\n");
- }
- return;
- }
- static int kona_timer_set_next_event(unsigned long clc,
- struct clock_event_device *unused)
- {
- /*
- * timer (0) is disabled by the timer interrupt already
- * so, here we reload the next event value and re-enable
- * the timer.
- *
- * This way, we are potentially losing the time between
- * timer-interrupt->set_next_event. CPU local timers, when
- * they come in should get rid of skew.
- */
- uint32_t lsw, msw;
- uint32_t reg;
- kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
- /* Load the "next" event tick value */
- writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);
- /* Enable compare */
- reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
- reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
- writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
- return 0;
- }
- static int kona_timer_shutdown(struct clock_event_device *evt)
- {
- kona_timer_disable_and_clear(timers.tmr_regs);
- return 0;
- }
- static struct clock_event_device kona_clockevent_timer = {
- .name = "timer 1",
- .features = CLOCK_EVT_FEAT_ONESHOT,
- .set_next_event = kona_timer_set_next_event,
- .set_state_shutdown = kona_timer_shutdown,
- .tick_resume = kona_timer_shutdown,
- };
- static void __init kona_timer_clockevents_init(void)
- {
- kona_clockevent_timer.cpumask = cpumask_of(0);
- clockevents_config_and_register(&kona_clockevent_timer,
- arch_timer_rate, 6, 0xffffffff);
- }
- static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
- {
- struct clock_event_device *evt = &kona_clockevent_timer;
- kona_timer_disable_and_clear(timers.tmr_regs);
- evt->event_handler(evt);
- return IRQ_HANDLED;
- }
- static struct irqaction kona_timer_irq = {
- .name = "Kona Timer Tick",
- .flags = IRQF_TIMER,
- .handler = kona_timer_interrupt,
- };
- static void __init kona_timer_init(struct device_node *node)
- {
- u32 freq;
- struct clk *external_clk;
- if (!of_device_is_available(node)) {
- pr_info("Kona Timer v1 marked as disabled in device tree\n");
- return;
- }
- external_clk = of_clk_get_by_name(node, NULL);
- if (!IS_ERR(external_clk)) {
- arch_timer_rate = clk_get_rate(external_clk);
- clk_prepare_enable(external_clk);
- } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
- arch_timer_rate = freq;
- } else {
- pr_err("Kona Timer v1 unable to determine clock-frequency");
- return;
- }
- /* Setup IRQ numbers */
- timers.tmr_irq = irq_of_parse_and_map(node, 0);
- /* Setup IO addresses */
- timers.tmr_regs = of_iomap(node, 0);
- kona_timer_disable_and_clear(timers.tmr_regs);
- kona_timer_clockevents_init();
- setup_irq(timers.tmr_irq, &kona_timer_irq);
- kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
- }
- CLOCKSOURCE_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
- /*
- * bcm,kona-timer is deprecated by brcm,kona-timer
- * being kept here for driver compatibility
- */
- CLOCKSOURCE_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);
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