1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Ralink System Tick Counter driver present on RT3352 and MT7620 SoCs. 4 * 5 * Copyright (C) 2013 by John Crispin <john@phrozen.org> 6 */ 7 8 #include <linux/clockchips.h> 9 #include <linux/clocksource.h> 10 #include <linux/interrupt.h> 11 #include <linux/reset.h> 12 #include <linux/init.h> 13 #include <linux/time.h> 14 #include <linux/of.h> 15 #include <linux/of_irq.h> 16 #include <linux/of_address.h> 17 18 #define SYSTICK_FREQ (50 * 1000) 19 20 #define SYSTICK_CONFIG 0x00 21 #define SYSTICK_COMPARE 0x04 22 #define SYSTICK_COUNT 0x08 23 24 /* route systick irq to mips irq 7 instead of the r4k-timer */ 25 #define CFG_EXT_STK_EN 0x2 26 /* enable the counter */ 27 #define CFG_CNT_EN 0x1 28 29 struct systick_device { 30 void __iomem *membase; 31 struct clock_event_device dev; 32 int irq_requested; 33 int freq_scale; 34 }; 35 36 static int systick_set_oneshot(struct clock_event_device *evt); 37 static int systick_shutdown(struct clock_event_device *evt); 38 39 static int systick_next_event(unsigned long delta, 40 struct clock_event_device *evt) 41 { 42 struct systick_device *sdev; 43 u32 count; 44 45 sdev = container_of(evt, struct systick_device, dev); 46 count = ioread32(sdev->membase + SYSTICK_COUNT); 47 count = (count + delta) % SYSTICK_FREQ; 48 iowrite32(count, sdev->membase + SYSTICK_COMPARE); 49 50 return 0; 51 } 52 53 static void systick_event_handler(struct clock_event_device *dev) 54 { 55 /* noting to do here */ 56 } 57 58 static irqreturn_t systick_interrupt(int irq, void *dev_id) 59 { 60 struct clock_event_device *dev = (struct clock_event_device *)dev_id; 61 62 dev->event_handler(dev); 63 64 return IRQ_HANDLED; 65 } 66 67 static struct systick_device systick = { 68 .dev = { 69 /* 70 * cevt-r4k uses 300, make sure systick 71 * gets used if available 72 */ 73 .rating = 310, 74 .features = CLOCK_EVT_FEAT_ONESHOT, 75 .set_next_event = systick_next_event, 76 .set_state_shutdown = systick_shutdown, 77 .set_state_oneshot = systick_set_oneshot, 78 .event_handler = systick_event_handler, 79 }, 80 }; 81 82 static int systick_shutdown(struct clock_event_device *evt) 83 { 84 struct systick_device *sdev; 85 86 sdev = container_of(evt, struct systick_device, dev); 87 88 if (sdev->irq_requested) 89 free_irq(systick.dev.irq, &systick.dev); 90 sdev->irq_requested = 0; 91 iowrite32(0, systick.membase + SYSTICK_CONFIG); 92 93 return 0; 94 } 95 96 static int systick_set_oneshot(struct clock_event_device *evt) 97 { 98 const char *name = systick.dev.name; 99 struct systick_device *sdev; 100 int irq = systick.dev.irq; 101 102 sdev = container_of(evt, struct systick_device, dev); 103 104 if (!sdev->irq_requested) { 105 if (request_irq(irq, systick_interrupt, 106 IRQF_PERCPU | IRQF_TIMER, name, &systick.dev)) 107 pr_err("Failed to request irq %d (%s)\n", irq, name); 108 } 109 sdev->irq_requested = 1; 110 iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN, 111 systick.membase + SYSTICK_CONFIG); 112 113 return 0; 114 } 115 116 static int __init ralink_systick_init(struct device_node *np) 117 { 118 int ret; 119 120 systick.membase = of_iomap(np, 0); 121 if (!systick.membase) 122 return -ENXIO; 123 124 systick.dev.name = np->name; 125 clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60); 126 systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev); 127 systick.dev.max_delta_ticks = 0x7fff; 128 systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev); 129 systick.dev.min_delta_ticks = 0x3; 130 systick.dev.irq = irq_of_parse_and_map(np, 0); 131 if (!systick.dev.irq) { 132 pr_err("%pOFn: request_irq failed", np); 133 return -EINVAL; 134 } 135 136 ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name, 137 SYSTICK_FREQ, 301, 16, 138 clocksource_mmio_readl_up); 139 if (ret) 140 return ret; 141 142 clockevents_register_device(&systick.dev); 143 144 pr_info("%pOFn: running - mult: %d, shift: %d\n", 145 np, systick.dev.mult, systick.dev.shift); 146 147 return 0; 148 } 149 150 TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init); 151