1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright 2012 Simon Arlott 4 */ 5 6 #include <linux/bitops.h> 7 #include <linux/clockchips.h> 8 #include <linux/clocksource.h> 9 #include <linux/interrupt.h> 10 #include <linux/irqreturn.h> 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <linux/of_address.h> 14 #include <linux/of_irq.h> 15 #include <linux/of_platform.h> 16 #include <linux/slab.h> 17 #include <linux/string.h> 18 #include <linux/sched_clock.h> 19 20 #include <asm/irq.h> 21 22 #define REG_CONTROL 0x00 23 #define REG_COUNTER_LO 0x04 24 #define REG_COUNTER_HI 0x08 25 #define REG_COMPARE(n) (0x0c + (n) * 4) 26 #define MAX_TIMER 3 27 #define DEFAULT_TIMER 3 28 29 struct bcm2835_timer { 30 void __iomem *control; 31 void __iomem *compare; 32 int match_mask; 33 struct clock_event_device evt; 34 struct irqaction act; 35 }; 36 37 static void __iomem *system_clock __read_mostly; 38 39 static u64 notrace bcm2835_sched_read(void) 40 { 41 return readl_relaxed(system_clock); 42 } 43 44 static int bcm2835_time_set_next_event(unsigned long event, 45 struct clock_event_device *evt_dev) 46 { 47 struct bcm2835_timer *timer = container_of(evt_dev, 48 struct bcm2835_timer, evt); 49 writel_relaxed(readl_relaxed(system_clock) + event, 50 timer->compare); 51 return 0; 52 } 53 54 static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id) 55 { 56 struct bcm2835_timer *timer = dev_id; 57 void (*event_handler)(struct clock_event_device *); 58 if (readl_relaxed(timer->control) & timer->match_mask) { 59 writel_relaxed(timer->match_mask, timer->control); 60 61 event_handler = READ_ONCE(timer->evt.event_handler); 62 if (event_handler) 63 event_handler(&timer->evt); 64 return IRQ_HANDLED; 65 } else { 66 return IRQ_NONE; 67 } 68 } 69 70 static int __init bcm2835_timer_init(struct device_node *node) 71 { 72 void __iomem *base; 73 u32 freq; 74 int irq, ret; 75 struct bcm2835_timer *timer; 76 77 base = of_iomap(node, 0); 78 if (!base) { 79 pr_err("Can't remap registers\n"); 80 return -ENXIO; 81 } 82 83 ret = of_property_read_u32(node, "clock-frequency", &freq); 84 if (ret) { 85 pr_err("Can't read clock-frequency\n"); 86 goto err_iounmap; 87 } 88 89 system_clock = base + REG_COUNTER_LO; 90 sched_clock_register(bcm2835_sched_read, 32, freq); 91 92 clocksource_mmio_init(base + REG_COUNTER_LO, node->name, 93 freq, 300, 32, clocksource_mmio_readl_up); 94 95 irq = irq_of_parse_and_map(node, DEFAULT_TIMER); 96 if (irq <= 0) { 97 pr_err("Can't parse IRQ\n"); 98 ret = -EINVAL; 99 goto err_iounmap; 100 } 101 102 timer = kzalloc(sizeof(*timer), GFP_KERNEL); 103 if (!timer) { 104 ret = -ENOMEM; 105 goto err_iounmap; 106 } 107 108 timer->control = base + REG_CONTROL; 109 timer->compare = base + REG_COMPARE(DEFAULT_TIMER); 110 timer->match_mask = BIT(DEFAULT_TIMER); 111 timer->evt.name = node->name; 112 timer->evt.rating = 300; 113 timer->evt.features = CLOCK_EVT_FEAT_ONESHOT; 114 timer->evt.set_next_event = bcm2835_time_set_next_event; 115 timer->evt.cpumask = cpumask_of(0); 116 timer->act.name = node->name; 117 timer->act.flags = IRQF_TIMER | IRQF_SHARED; 118 timer->act.dev_id = timer; 119 timer->act.handler = bcm2835_time_interrupt; 120 121 ret = setup_irq(irq, &timer->act); 122 if (ret) { 123 pr_err("Can't set up timer IRQ\n"); 124 goto err_timer_free; 125 } 126 127 clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff); 128 129 pr_info("bcm2835: system timer (irq = %d)\n", irq); 130 131 return 0; 132 133 err_timer_free: 134 kfree(timer); 135 136 err_iounmap: 137 iounmap(base); 138 return ret; 139 } 140 TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer", 141 bcm2835_timer_init); 142