| /* |
| * 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 void kona_timer_set_mode(enum clock_event_mode mode, |
| struct clock_event_device *unused) |
| { |
| switch (mode) { |
| case CLOCK_EVT_MODE_ONESHOT: |
| /* by default mode is one shot don't do any thing */ |
| break; |
| case CLOCK_EVT_MODE_UNUSED: |
| case CLOCK_EVT_MODE_SHUTDOWN: |
| default: |
| kona_timer_disable_and_clear(timers.tmr_regs); |
| } |
| } |
| |
| 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_mode = kona_timer_set_mode |
| }; |
| |
| 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); |