1 /* 2 * Copyright (C) 2012 Broadcom Corporation 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation version 2. 7 * 8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any 9 * kind, whether express or implied; without even the implied warranty 10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 14 #include <linux/init.h> 15 #include <linux/irq.h> 16 #include <linux/interrupt.h> 17 #include <linux/jiffies.h> 18 #include <linux/clockchips.h> 19 #include <linux/types.h> 20 21 #include <linux/io.h> 22 #include <asm/mach/time.h> 23 24 #include <linux/of.h> 25 #include <linux/of_address.h> 26 #include <linux/of_irq.h> 27 28 29 #define KONA_GPTIMER_STCS_OFFSET 0x00000000 30 #define KONA_GPTIMER_STCLO_OFFSET 0x00000004 31 #define KONA_GPTIMER_STCHI_OFFSET 0x00000008 32 #define KONA_GPTIMER_STCM0_OFFSET 0x0000000C 33 34 #define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 0 35 #define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 4 36 37 struct kona_bcm_timers { 38 int tmr_irq; 39 void __iomem *tmr_regs; 40 }; 41 42 static struct kona_bcm_timers timers; 43 44 static u32 arch_timer_rate; 45 46 /* 47 * We use the peripheral timers for system tick, the cpu global timer for 48 * profile tick 49 */ 50 static void kona_timer_disable_and_clear(void __iomem *base) 51 { 52 uint32_t reg; 53 54 /* 55 * clear and disable interrupts 56 * We are using compare/match register 0 for our system interrupts 57 */ 58 reg = readl(base + KONA_GPTIMER_STCS_OFFSET); 59 60 /* Clear compare (0) interrupt */ 61 reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT; 62 /* disable compare */ 63 reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT); 64 65 writel(reg, base + KONA_GPTIMER_STCS_OFFSET); 66 67 } 68 69 static void 70 kona_timer_get_counter(void *timer_base, uint32_t *msw, uint32_t *lsw) 71 { 72 void __iomem *base = IOMEM(timer_base); 73 int loop_limit = 4; 74 75 /* 76 * Read 64-bit free running counter 77 * 1. Read hi-word 78 * 2. Read low-word 79 * 3. Read hi-word again 80 * 4.1 81 * if new hi-word is not equal to previously read hi-word, then 82 * start from #1 83 * 4.2 84 * if new hi-word is equal to previously read hi-word then stop. 85 */ 86 87 while (--loop_limit) { 88 *msw = readl(base + KONA_GPTIMER_STCHI_OFFSET); 89 *lsw = readl(base + KONA_GPTIMER_STCLO_OFFSET); 90 if (*msw == readl(base + KONA_GPTIMER_STCHI_OFFSET)) 91 break; 92 } 93 if (!loop_limit) { 94 pr_err("bcm_kona_timer: getting counter failed.\n"); 95 pr_err(" Timer will be impacted\n"); 96 } 97 98 return; 99 } 100 101 static const struct of_device_id bcm_timer_ids[] __initconst = { 102 {.compatible = "brcm,kona-timer"}, 103 {.compatible = "bcm,kona-timer"}, /* deprecated name */ 104 {}, 105 }; 106 107 static void __init kona_timers_init(struct device_node *node) 108 { 109 u32 freq; 110 111 if (!of_property_read_u32(node, "clock-frequency", &freq)) 112 arch_timer_rate = freq; 113 else 114 panic("clock-frequency not set in the .dts file"); 115 116 /* Setup IRQ numbers */ 117 timers.tmr_irq = irq_of_parse_and_map(node, 0); 118 119 /* Setup IO addresses */ 120 timers.tmr_regs = of_iomap(node, 0); 121 122 kona_timer_disable_and_clear(timers.tmr_regs); 123 } 124 125 static int kona_timer_set_next_event(unsigned long clc, 126 struct clock_event_device *unused) 127 { 128 /* 129 * timer (0) is disabled by the timer interrupt already 130 * so, here we reload the next event value and re-enable 131 * the timer. 132 * 133 * This way, we are potentially losing the time between 134 * timer-interrupt->set_next_event. CPU local timers, when 135 * they come in should get rid of skew. 136 */ 137 138 uint32_t lsw, msw; 139 uint32_t reg; 140 141 kona_timer_get_counter(timers.tmr_regs, &msw, &lsw); 142 143 /* Load the "next" event tick value */ 144 writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET); 145 146 /* Enable compare */ 147 reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET); 148 reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT); 149 writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET); 150 151 return 0; 152 } 153 154 static void kona_timer_set_mode(enum clock_event_mode mode, 155 struct clock_event_device *unused) 156 { 157 switch (mode) { 158 case CLOCK_EVT_MODE_ONESHOT: 159 /* by default mode is one shot don't do any thing */ 160 break; 161 case CLOCK_EVT_MODE_UNUSED: 162 case CLOCK_EVT_MODE_SHUTDOWN: 163 default: 164 kona_timer_disable_and_clear(timers.tmr_regs); 165 } 166 } 167 168 static struct clock_event_device kona_clockevent_timer = { 169 .name = "timer 1", 170 .features = CLOCK_EVT_FEAT_ONESHOT, 171 .set_next_event = kona_timer_set_next_event, 172 .set_mode = kona_timer_set_mode 173 }; 174 175 static void __init kona_timer_clockevents_init(void) 176 { 177 kona_clockevent_timer.cpumask = cpumask_of(0); 178 clockevents_config_and_register(&kona_clockevent_timer, 179 arch_timer_rate, 6, 0xffffffff); 180 } 181 182 static irqreturn_t kona_timer_interrupt(int irq, void *dev_id) 183 { 184 struct clock_event_device *evt = &kona_clockevent_timer; 185 186 kona_timer_disable_and_clear(timers.tmr_regs); 187 evt->event_handler(evt); 188 return IRQ_HANDLED; 189 } 190 191 static struct irqaction kona_timer_irq = { 192 .name = "Kona Timer Tick", 193 .flags = IRQF_TIMER, 194 .handler = kona_timer_interrupt, 195 }; 196 197 static void __init kona_timer_init(struct device_node *node) 198 { 199 kona_timers_init(node); 200 kona_timer_clockevents_init(); 201 setup_irq(timers.tmr_irq, &kona_timer_irq); 202 kona_timer_set_next_event((arch_timer_rate / HZ), NULL); 203 } 204 205 CLOCKSOURCE_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init); 206 /* 207 * bcm,kona-timer is deprecated by brcm,kona-timer 208 * being kept here for driver compatibility 209 */ 210 CLOCKSOURCE_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init); 211