193 lines · c
1// SPDX-License-Identifier: GPL-2.02// Copyright (C) 2012 Broadcom Corporation3 4#include <linux/init.h>5#include <linux/irq.h>6#include <linux/interrupt.h>7#include <linux/jiffies.h>8#include <linux/clockchips.h>9#include <linux/types.h>10#include <linux/clk.h>11 12#include <linux/io.h>13 14#include <linux/of.h>15#include <linux/of_address.h>16#include <linux/of_irq.h>17 18 19#define KONA_GPTIMER_STCS_OFFSET 0x0000000020#define KONA_GPTIMER_STCLO_OFFSET 0x0000000421#define KONA_GPTIMER_STCHI_OFFSET 0x0000000822#define KONA_GPTIMER_STCM0_OFFSET 0x0000000C23 24#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 025#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 426 27struct kona_bcm_timers {28 int tmr_irq;29 void __iomem *tmr_regs;30};31 32static struct kona_bcm_timers timers;33 34static u32 arch_timer_rate;35 36/*37 * We use the peripheral timers for system tick, the cpu global timer for38 * profile tick39 */40static void kona_timer_disable_and_clear(void __iomem *base)41{42 uint32_t reg;43 44 /*45 * clear and disable interrupts46 * We are using compare/match register 0 for our system interrupts47 */48 reg = readl(base + KONA_GPTIMER_STCS_OFFSET);49 50 /* Clear compare (0) interrupt */51 reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;52 /* disable compare */53 reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);54 55 writel(reg, base + KONA_GPTIMER_STCS_OFFSET);56 57}58 59static int60kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)61{62 int loop_limit = 3;63 64 /*65 * Read 64-bit free running counter66 * 1. Read hi-word67 * 2. Read low-word68 * 3. Read hi-word again69 * 4.170 * if new hi-word is not equal to previously read hi-word, then71 * start from #172 * 4.273 * if new hi-word is equal to previously read hi-word then stop.74 */75 76 do {77 *msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);78 *lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);79 if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))80 break;81 } while (--loop_limit);82 if (!loop_limit) {83 pr_err("bcm_kona_timer: getting counter failed.\n");84 pr_err(" Timer will be impacted\n");85 return -ETIMEDOUT;86 }87 88 return 0;89}90 91static int kona_timer_set_next_event(unsigned long clc,92 struct clock_event_device *unused)93{94 /*95 * timer (0) is disabled by the timer interrupt already96 * so, here we reload the next event value and re-enable97 * the timer.98 *99 * This way, we are potentially losing the time between100 * timer-interrupt->set_next_event. CPU local timers, when101 * they come in should get rid of skew.102 */103 104 uint32_t lsw, msw;105 uint32_t reg;106 int ret;107 108 ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);109 if (ret)110 return ret;111 112 /* Load the "next" event tick value */113 writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);114 115 /* Enable compare */116 reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);117 reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);118 writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);119 120 return 0;121}122 123static int kona_timer_shutdown(struct clock_event_device *evt)124{125 kona_timer_disable_and_clear(timers.tmr_regs);126 return 0;127}128 129static struct clock_event_device kona_clockevent_timer = {130 .name = "timer 1",131 .features = CLOCK_EVT_FEAT_ONESHOT,132 .set_next_event = kona_timer_set_next_event,133 .set_state_shutdown = kona_timer_shutdown,134 .tick_resume = kona_timer_shutdown,135};136 137static void __init kona_timer_clockevents_init(void)138{139 kona_clockevent_timer.cpumask = cpumask_of(0);140 clockevents_config_and_register(&kona_clockevent_timer,141 arch_timer_rate, 6, 0xffffffff);142}143 144static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)145{146 struct clock_event_device *evt = &kona_clockevent_timer;147 148 kona_timer_disable_and_clear(timers.tmr_regs);149 evt->event_handler(evt);150 return IRQ_HANDLED;151}152 153static int __init kona_timer_init(struct device_node *node)154{155 u32 freq;156 struct clk *external_clk;157 158 external_clk = of_clk_get_by_name(node, NULL);159 160 if (!IS_ERR(external_clk)) {161 arch_timer_rate = clk_get_rate(external_clk);162 clk_prepare_enable(external_clk);163 } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {164 arch_timer_rate = freq;165 } else {166 pr_err("Kona Timer v1 unable to determine clock-frequency\n");167 return -EINVAL;168 }169 170 /* Setup IRQ numbers */171 timers.tmr_irq = irq_of_parse_and_map(node, 0);172 173 /* Setup IO addresses */174 timers.tmr_regs = of_iomap(node, 0);175 176 kona_timer_disable_and_clear(timers.tmr_regs);177 178 kona_timer_clockevents_init();179 if (request_irq(timers.tmr_irq, kona_timer_interrupt, IRQF_TIMER,180 "Kona Timer Tick", NULL))181 pr_err("%s: request_irq() failed\n", "Kona Timer Tick");182 kona_timer_set_next_event((arch_timer_rate / HZ), NULL);183 184 return 0;185}186 187TIMER_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);188/*189 * bcm,kona-timer is deprecated by brcm,kona-timer190 * being kept here for driver compatibility191 */192TIMER_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);193