1 /* 2 * Time related functions for Hexagon architecture 3 * 4 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 and 8 * only version 2 as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18 * 02110-1301, USA. 19 */ 20 21 #include <linux/init.h> 22 #include <linux/clockchips.h> 23 #include <linux/clocksource.h> 24 #include <linux/interrupt.h> 25 #include <linux/err.h> 26 #include <linux/platform_device.h> 27 #include <linux/ioport.h> 28 #include <linux/of.h> 29 #include <linux/of_address.h> 30 #include <linux/of_irq.h> 31 #include <linux/module.h> 32 33 #include <asm/timer-regs.h> 34 #include <asm/hexagon_vm.h> 35 36 /* 37 * For the clocksource we need: 38 * pcycle frequency (600MHz) 39 * For the loops_per_jiffy we need: 40 * thread/cpu frequency (100MHz) 41 * And for the timer, we need: 42 * sleep clock rate 43 */ 44 45 cycles_t pcycle_freq_mhz; 46 cycles_t thread_freq_mhz; 47 cycles_t sleep_clk_freq; 48 49 static struct resource rtos_timer_resources[] = { 50 { 51 .start = RTOS_TIMER_REGS_ADDR, 52 .end = RTOS_TIMER_REGS_ADDR+PAGE_SIZE-1, 53 .flags = IORESOURCE_MEM, 54 }, 55 }; 56 57 static struct platform_device rtos_timer_device = { 58 .name = "rtos_timer", 59 .id = -1, 60 .num_resources = ARRAY_SIZE(rtos_timer_resources), 61 .resource = rtos_timer_resources, 62 }; 63 64 /* A lot of this stuff should move into a platform specific section. */ 65 struct adsp_hw_timer_struct { 66 u32 match; /* Match value */ 67 u32 count; 68 u32 enable; /* [1] - CLR_ON_MATCH_EN, [0] - EN */ 69 u32 clear; /* one-shot register that clears the count */ 70 }; 71 72 /* Look for "TCX0" for related constants. */ 73 static __iomem struct adsp_hw_timer_struct *rtos_timer; 74 75 static u64 timer_get_cycles(struct clocksource *cs) 76 { 77 return (u64) __vmgettime(); 78 } 79 80 static struct clocksource hexagon_clocksource = { 81 .name = "pcycles", 82 .rating = 250, 83 .read = timer_get_cycles, 84 .mask = CLOCKSOURCE_MASK(64), 85 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 86 }; 87 88 static int set_next_event(unsigned long delta, struct clock_event_device *evt) 89 { 90 /* Assuming the timer will be disabled when we enter here. */ 91 92 iowrite32(1, &rtos_timer->clear); 93 iowrite32(0, &rtos_timer->clear); 94 95 iowrite32(delta, &rtos_timer->match); 96 iowrite32(1 << TIMER_ENABLE, &rtos_timer->enable); 97 return 0; 98 } 99 100 #ifdef CONFIG_SMP 101 /* Broadcast mechanism */ 102 static void broadcast(const struct cpumask *mask) 103 { 104 send_ipi(mask, IPI_TIMER); 105 } 106 #endif 107 108 /* XXX Implement set_state_shutdown() */ 109 static struct clock_event_device hexagon_clockevent_dev = { 110 .name = "clockevent", 111 .features = CLOCK_EVT_FEAT_ONESHOT, 112 .rating = 400, 113 .irq = RTOS_TIMER_INT, 114 .set_next_event = set_next_event, 115 #ifdef CONFIG_SMP 116 .broadcast = broadcast, 117 #endif 118 }; 119 120 #ifdef CONFIG_SMP 121 static DEFINE_PER_CPU(struct clock_event_device, clock_events); 122 123 void setup_percpu_clockdev(void) 124 { 125 int cpu = smp_processor_id(); 126 struct clock_event_device *ce_dev = &hexagon_clockevent_dev; 127 struct clock_event_device *dummy_clock_dev = 128 &per_cpu(clock_events, cpu); 129 130 memcpy(dummy_clock_dev, ce_dev, sizeof(*dummy_clock_dev)); 131 INIT_LIST_HEAD(&dummy_clock_dev->list); 132 133 dummy_clock_dev->features = CLOCK_EVT_FEAT_DUMMY; 134 dummy_clock_dev->cpumask = cpumask_of(cpu); 135 136 clockevents_register_device(dummy_clock_dev); 137 } 138 139 /* Called from smp.c for each CPU's timer ipi call */ 140 void ipi_timer(void) 141 { 142 int cpu = smp_processor_id(); 143 struct clock_event_device *ce_dev = &per_cpu(clock_events, cpu); 144 145 ce_dev->event_handler(ce_dev); 146 } 147 #endif /* CONFIG_SMP */ 148 149 static irqreturn_t timer_interrupt(int irq, void *devid) 150 { 151 struct clock_event_device *ce_dev = &hexagon_clockevent_dev; 152 153 iowrite32(0, &rtos_timer->enable); 154 ce_dev->event_handler(ce_dev); 155 156 return IRQ_HANDLED; 157 } 158 159 /* This should also be pulled from devtree */ 160 static struct irqaction rtos_timer_intdesc = { 161 .handler = timer_interrupt, 162 .flags = IRQF_TIMER | IRQF_TRIGGER_RISING, 163 .name = "rtos_timer" 164 }; 165 166 /* 167 * time_init_deferred - called by start_kernel to set up timer/clock source 168 * 169 * Install the IRQ handler for the clock, setup timers. 170 * This is done late, as that way, we can use ioremap(). 171 * 172 * This runs just before the delay loop is calibrated, and 173 * is used for delay calibration. 174 */ 175 void __init time_init_deferred(void) 176 { 177 struct resource *resource = NULL; 178 struct clock_event_device *ce_dev = &hexagon_clockevent_dev; 179 180 ce_dev->cpumask = cpu_all_mask; 181 182 if (!resource) 183 resource = rtos_timer_device.resource; 184 185 /* ioremap here means this has to run later, after paging init */ 186 rtos_timer = ioremap(resource->start, resource_size(resource)); 187 188 if (!rtos_timer) { 189 release_mem_region(resource->start, resource_size(resource)); 190 } 191 clocksource_register_khz(&hexagon_clocksource, pcycle_freq_mhz * 1000); 192 193 /* Note: the sim generic RTOS clock is apparently really 18750Hz */ 194 195 /* 196 * Last arg is some guaranteed seconds for which the conversion will 197 * work without overflow. 198 */ 199 clockevents_calc_mult_shift(ce_dev, sleep_clk_freq, 4); 200 201 ce_dev->max_delta_ns = clockevent_delta2ns(0x7fffffff, ce_dev); 202 ce_dev->min_delta_ns = clockevent_delta2ns(0xf, ce_dev); 203 204 #ifdef CONFIG_SMP 205 setup_percpu_clockdev(); 206 #endif 207 208 clockevents_register_device(ce_dev); 209 setup_irq(ce_dev->irq, &rtos_timer_intdesc); 210 } 211 212 void __init time_init(void) 213 { 214 late_time_init = time_init_deferred; 215 } 216 217 void __delay(unsigned long cycles) 218 { 219 unsigned long long start = __vmgettime(); 220 221 while ((__vmgettime() - start) < cycles) 222 cpu_relax(); 223 } 224 EXPORT_SYMBOL(__delay); 225 226 /* 227 * This could become parametric or perhaps even computed at run-time, 228 * but for now we take the observed simulator jitter. 229 */ 230 static long long fudgefactor = 350; /* Maybe lower if kernel optimized. */ 231 232 void __udelay(unsigned long usecs) 233 { 234 unsigned long long start = __vmgettime(); 235 unsigned long long finish = (pcycle_freq_mhz * usecs) - fudgefactor; 236 237 while ((__vmgettime() - start) < finish) 238 cpu_relax(); /* not sure how this improves readability */ 239 } 240 EXPORT_SYMBOL(__udelay); 241