1 /* 2 * Copyright (C) 2013-2014 Altera Corporation 3 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch> 4 * Copyright (C) 2004 Microtronix Datacom Ltd. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 */ 10 11 #include <linux/export.h> 12 #include <linux/interrupt.h> 13 #include <linux/clockchips.h> 14 #include <linux/clocksource.h> 15 #include <linux/delay.h> 16 #include <linux/of.h> 17 #include <linux/of_address.h> 18 #include <linux/of_irq.h> 19 #include <linux/io.h> 20 #include <linux/slab.h> 21 22 #define ALTR_TIMER_COMPATIBLE "altr,timer-1.0" 23 24 #define ALTERA_TIMER_STATUS_REG 0 25 #define ALTERA_TIMER_CONTROL_REG 4 26 #define ALTERA_TIMER_PERIODL_REG 8 27 #define ALTERA_TIMER_PERIODH_REG 12 28 #define ALTERA_TIMER_SNAPL_REG 16 29 #define ALTERA_TIMER_SNAPH_REG 20 30 31 #define ALTERA_TIMER_CONTROL_ITO_MSK (0x1) 32 #define ALTERA_TIMER_CONTROL_CONT_MSK (0x2) 33 #define ALTERA_TIMER_CONTROL_START_MSK (0x4) 34 #define ALTERA_TIMER_CONTROL_STOP_MSK (0x8) 35 36 struct nios2_timer { 37 void __iomem *base; 38 unsigned long freq; 39 }; 40 41 struct nios2_clockevent_dev { 42 struct nios2_timer timer; 43 struct clock_event_device ced; 44 }; 45 46 struct nios2_clocksource { 47 struct nios2_timer timer; 48 struct clocksource cs; 49 }; 50 51 static inline struct nios2_clockevent_dev * 52 to_nios2_clkevent(struct clock_event_device *evt) 53 { 54 return container_of(evt, struct nios2_clockevent_dev, ced); 55 } 56 57 static inline struct nios2_clocksource * 58 to_nios2_clksource(struct clocksource *cs) 59 { 60 return container_of(cs, struct nios2_clocksource, cs); 61 } 62 63 static u16 timer_readw(struct nios2_timer *timer, u32 offs) 64 { 65 return readw(timer->base + offs); 66 } 67 68 static void timer_writew(struct nios2_timer *timer, u16 val, u32 offs) 69 { 70 writew(val, timer->base + offs); 71 } 72 73 static inline unsigned long read_timersnapshot(struct nios2_timer *timer) 74 { 75 unsigned long count; 76 77 timer_writew(timer, 0, ALTERA_TIMER_SNAPL_REG); 78 count = timer_readw(timer, ALTERA_TIMER_SNAPH_REG) << 16 | 79 timer_readw(timer, ALTERA_TIMER_SNAPL_REG); 80 81 return count; 82 } 83 84 static cycle_t nios2_timer_read(struct clocksource *cs) 85 { 86 struct nios2_clocksource *nios2_cs = to_nios2_clksource(cs); 87 unsigned long flags; 88 u32 count; 89 90 local_irq_save(flags); 91 count = read_timersnapshot(&nios2_cs->timer); 92 local_irq_restore(flags); 93 94 /* Counter is counting down */ 95 return ~count; 96 } 97 98 static struct nios2_clocksource nios2_cs = { 99 .cs = { 100 .name = "nios2-clksrc", 101 .rating = 250, 102 .read = nios2_timer_read, 103 .mask = CLOCKSOURCE_MASK(32), 104 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 105 }, 106 }; 107 108 cycles_t get_cycles(void) 109 { 110 return nios2_timer_read(&nios2_cs.cs); 111 } 112 EXPORT_SYMBOL(get_cycles); 113 114 static void nios2_timer_start(struct nios2_timer *timer) 115 { 116 u16 ctrl; 117 118 ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG); 119 ctrl |= ALTERA_TIMER_CONTROL_START_MSK; 120 timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG); 121 } 122 123 static void nios2_timer_stop(struct nios2_timer *timer) 124 { 125 u16 ctrl; 126 127 ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG); 128 ctrl |= ALTERA_TIMER_CONTROL_STOP_MSK; 129 timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG); 130 } 131 132 static void nios2_timer_config(struct nios2_timer *timer, unsigned long period, 133 bool periodic) 134 { 135 u16 ctrl; 136 137 /* The timer's actual period is one cycle greater than the value 138 * stored in the period register. */ 139 period--; 140 141 ctrl = timer_readw(timer, ALTERA_TIMER_CONTROL_REG); 142 /* stop counter */ 143 timer_writew(timer, ctrl | ALTERA_TIMER_CONTROL_STOP_MSK, 144 ALTERA_TIMER_CONTROL_REG); 145 146 /* write new count */ 147 timer_writew(timer, period, ALTERA_TIMER_PERIODL_REG); 148 timer_writew(timer, period >> 16, ALTERA_TIMER_PERIODH_REG); 149 150 ctrl |= ALTERA_TIMER_CONTROL_START_MSK | ALTERA_TIMER_CONTROL_ITO_MSK; 151 if (periodic) 152 ctrl |= ALTERA_TIMER_CONTROL_CONT_MSK; 153 else 154 ctrl &= ~ALTERA_TIMER_CONTROL_CONT_MSK; 155 timer_writew(timer, ctrl, ALTERA_TIMER_CONTROL_REG); 156 } 157 158 static int nios2_timer_set_next_event(unsigned long delta, 159 struct clock_event_device *evt) 160 { 161 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); 162 163 nios2_timer_config(&nios2_ced->timer, delta, false); 164 165 return 0; 166 } 167 168 static int nios2_timer_shutdown(struct clock_event_device *evt) 169 { 170 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); 171 struct nios2_timer *timer = &nios2_ced->timer; 172 173 nios2_timer_stop(timer); 174 return 0; 175 } 176 177 static int nios2_timer_set_periodic(struct clock_event_device *evt) 178 { 179 unsigned long period; 180 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); 181 struct nios2_timer *timer = &nios2_ced->timer; 182 183 period = DIV_ROUND_UP(timer->freq, HZ); 184 nios2_timer_config(timer, period, true); 185 return 0; 186 } 187 188 static int nios2_timer_resume(struct clock_event_device *evt) 189 { 190 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); 191 struct nios2_timer *timer = &nios2_ced->timer; 192 193 nios2_timer_start(timer); 194 return 0; 195 } 196 197 irqreturn_t timer_interrupt(int irq, void *dev_id) 198 { 199 struct clock_event_device *evt = (struct clock_event_device *) dev_id; 200 struct nios2_clockevent_dev *nios2_ced = to_nios2_clkevent(evt); 201 202 /* Clear the interrupt condition */ 203 timer_writew(&nios2_ced->timer, 0, ALTERA_TIMER_STATUS_REG); 204 evt->event_handler(evt); 205 206 return IRQ_HANDLED; 207 } 208 209 static void __init nios2_timer_get_base_and_freq(struct device_node *np, 210 void __iomem **base, u32 *freq) 211 { 212 *base = of_iomap(np, 0); 213 if (!*base) 214 panic("Unable to map reg for %s\n", np->name); 215 216 if (of_property_read_u32(np, "clock-frequency", freq)) 217 panic("Unable to get %s clock frequency\n", np->name); 218 } 219 220 static struct nios2_clockevent_dev nios2_ce = { 221 .ced = { 222 .name = "nios2-clkevent", 223 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, 224 .rating = 250, 225 .shift = 32, 226 .set_next_event = nios2_timer_set_next_event, 227 .set_state_shutdown = nios2_timer_shutdown, 228 .set_state_periodic = nios2_timer_set_periodic, 229 .set_state_oneshot = nios2_timer_shutdown, 230 .tick_resume = nios2_timer_resume, 231 }, 232 }; 233 234 static __init void nios2_clockevent_init(struct device_node *timer) 235 { 236 void __iomem *iobase; 237 u32 freq; 238 int irq; 239 240 nios2_timer_get_base_and_freq(timer, &iobase, &freq); 241 242 irq = irq_of_parse_and_map(timer, 0); 243 if (!irq) 244 panic("Unable to parse timer irq\n"); 245 246 nios2_ce.timer.base = iobase; 247 nios2_ce.timer.freq = freq; 248 249 nios2_ce.ced.cpumask = cpumask_of(0); 250 nios2_ce.ced.irq = irq; 251 252 nios2_timer_stop(&nios2_ce.timer); 253 /* clear pending interrupt */ 254 timer_writew(&nios2_ce.timer, 0, ALTERA_TIMER_STATUS_REG); 255 256 if (request_irq(irq, timer_interrupt, IRQF_TIMER, timer->name, 257 &nios2_ce.ced)) 258 panic("Unable to setup timer irq\n"); 259 260 clockevents_config_and_register(&nios2_ce.ced, freq, 1, ULONG_MAX); 261 } 262 263 static __init void nios2_clocksource_init(struct device_node *timer) 264 { 265 unsigned int ctrl; 266 void __iomem *iobase; 267 u32 freq; 268 269 nios2_timer_get_base_and_freq(timer, &iobase, &freq); 270 271 nios2_cs.timer.base = iobase; 272 nios2_cs.timer.freq = freq; 273 274 clocksource_register_hz(&nios2_cs.cs, freq); 275 276 timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODL_REG); 277 timer_writew(&nios2_cs.timer, USHRT_MAX, ALTERA_TIMER_PERIODH_REG); 278 279 /* interrupt disable + continuous + start */ 280 ctrl = ALTERA_TIMER_CONTROL_CONT_MSK | ALTERA_TIMER_CONTROL_START_MSK; 281 timer_writew(&nios2_cs.timer, ctrl, ALTERA_TIMER_CONTROL_REG); 282 283 /* Calibrate the delay loop directly */ 284 lpj_fine = freq / HZ; 285 } 286 287 /* 288 * The first timer instance will use as a clockevent. If there are two or 289 * more instances, the second one gets used as clocksource and all 290 * others are unused. 291 */ 292 static void __init nios2_time_init(struct device_node *timer) 293 { 294 static int num_called; 295 296 switch (num_called) { 297 case 0: 298 nios2_clockevent_init(timer); 299 break; 300 case 1: 301 nios2_clocksource_init(timer); 302 break; 303 default: 304 break; 305 } 306 307 num_called++; 308 } 309 310 void read_persistent_clock(struct timespec *ts) 311 { 312 ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0); 313 ts->tv_nsec = 0; 314 } 315 316 void __init time_init(void) 317 { 318 struct device_node *np; 319 int count = 0; 320 321 for_each_compatible_node(np, NULL, ALTR_TIMER_COMPATIBLE) 322 count++; 323 324 if (count < 2) 325 panic("%d timer is found, it needs 2 timers in system\n", count); 326 327 clocksource_of_init(); 328 } 329 330 CLOCKSOURCE_OF_DECLARE(nios2_timer, ALTR_TIMER_COMPATIBLE, nios2_time_init); 331