1 /* 2 * Emma Mobile Timer Support - STI 3 * 4 * Copyright (C) 2012 Magnus Damm 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 as published by 8 * the Free Software Foundation; either version 2 of the License 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 */ 19 20 #include <linux/init.h> 21 #include <linux/platform_device.h> 22 #include <linux/spinlock.h> 23 #include <linux/interrupt.h> 24 #include <linux/ioport.h> 25 #include <linux/io.h> 26 #include <linux/clk.h> 27 #include <linux/irq.h> 28 #include <linux/err.h> 29 #include <linux/delay.h> 30 #include <linux/clocksource.h> 31 #include <linux/clockchips.h> 32 #include <linux/slab.h> 33 #include <linux/module.h> 34 35 enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; 36 37 struct em_sti_priv { 38 void __iomem *base; 39 struct clk *clk; 40 struct platform_device *pdev; 41 unsigned int active[USER_NR]; 42 unsigned long rate; 43 raw_spinlock_t lock; 44 struct clock_event_device ced; 45 struct clocksource cs; 46 }; 47 48 #define STI_CONTROL 0x00 49 #define STI_COMPA_H 0x10 50 #define STI_COMPA_L 0x14 51 #define STI_COMPB_H 0x18 52 #define STI_COMPB_L 0x1c 53 #define STI_COUNT_H 0x20 54 #define STI_COUNT_L 0x24 55 #define STI_COUNT_RAW_H 0x28 56 #define STI_COUNT_RAW_L 0x2c 57 #define STI_SET_H 0x30 58 #define STI_SET_L 0x34 59 #define STI_INTSTATUS 0x40 60 #define STI_INTRAWSTATUS 0x44 61 #define STI_INTENSET 0x48 62 #define STI_INTENCLR 0x4c 63 #define STI_INTFFCLR 0x50 64 65 static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) 66 { 67 return ioread32(p->base + offs); 68 } 69 70 static inline void em_sti_write(struct em_sti_priv *p, int offs, 71 unsigned long value) 72 { 73 iowrite32(value, p->base + offs); 74 } 75 76 static int em_sti_enable(struct em_sti_priv *p) 77 { 78 int ret; 79 80 /* enable clock */ 81 ret = clk_enable(p->clk); 82 if (ret) { 83 dev_err(&p->pdev->dev, "cannot enable clock\n"); 84 return ret; 85 } 86 87 /* reset the counter */ 88 em_sti_write(p, STI_SET_H, 0x40000000); 89 em_sti_write(p, STI_SET_L, 0x00000000); 90 91 /* mask and clear pending interrupts */ 92 em_sti_write(p, STI_INTENCLR, 3); 93 em_sti_write(p, STI_INTFFCLR, 3); 94 95 /* enable updates of counter registers */ 96 em_sti_write(p, STI_CONTROL, 1); 97 98 return 0; 99 } 100 101 static void em_sti_disable(struct em_sti_priv *p) 102 { 103 /* mask interrupts */ 104 em_sti_write(p, STI_INTENCLR, 3); 105 106 /* stop clock */ 107 clk_disable(p->clk); 108 } 109 110 static u64 em_sti_count(struct em_sti_priv *p) 111 { 112 u64 ticks; 113 unsigned long flags; 114 115 /* the STI hardware buffers the 48-bit count, but to 116 * break it out into two 32-bit access the registers 117 * must be accessed in a certain order. 118 * Always read STI_COUNT_H before STI_COUNT_L. 119 */ 120 raw_spin_lock_irqsave(&p->lock, flags); 121 ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32; 122 ticks |= em_sti_read(p, STI_COUNT_L); 123 raw_spin_unlock_irqrestore(&p->lock, flags); 124 125 return ticks; 126 } 127 128 static u64 em_sti_set_next(struct em_sti_priv *p, u64 next) 129 { 130 unsigned long flags; 131 132 raw_spin_lock_irqsave(&p->lock, flags); 133 134 /* mask compare A interrupt */ 135 em_sti_write(p, STI_INTENCLR, 1); 136 137 /* update compare A value */ 138 em_sti_write(p, STI_COMPA_H, next >> 32); 139 em_sti_write(p, STI_COMPA_L, next & 0xffffffff); 140 141 /* clear compare A interrupt source */ 142 em_sti_write(p, STI_INTFFCLR, 1); 143 144 /* unmask compare A interrupt */ 145 em_sti_write(p, STI_INTENSET, 1); 146 147 raw_spin_unlock_irqrestore(&p->lock, flags); 148 149 return next; 150 } 151 152 static irqreturn_t em_sti_interrupt(int irq, void *dev_id) 153 { 154 struct em_sti_priv *p = dev_id; 155 156 p->ced.event_handler(&p->ced); 157 return IRQ_HANDLED; 158 } 159 160 static int em_sti_start(struct em_sti_priv *p, unsigned int user) 161 { 162 unsigned long flags; 163 int used_before; 164 int ret = 0; 165 166 raw_spin_lock_irqsave(&p->lock, flags); 167 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; 168 if (!used_before) 169 ret = em_sti_enable(p); 170 171 if (!ret) 172 p->active[user] = 1; 173 raw_spin_unlock_irqrestore(&p->lock, flags); 174 175 return ret; 176 } 177 178 static void em_sti_stop(struct em_sti_priv *p, unsigned int user) 179 { 180 unsigned long flags; 181 int used_before, used_after; 182 183 raw_spin_lock_irqsave(&p->lock, flags); 184 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; 185 p->active[user] = 0; 186 used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; 187 188 if (used_before && !used_after) 189 em_sti_disable(p); 190 raw_spin_unlock_irqrestore(&p->lock, flags); 191 } 192 193 static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) 194 { 195 return container_of(cs, struct em_sti_priv, cs); 196 } 197 198 static u64 em_sti_clocksource_read(struct clocksource *cs) 199 { 200 return em_sti_count(cs_to_em_sti(cs)); 201 } 202 203 static int em_sti_clocksource_enable(struct clocksource *cs) 204 { 205 struct em_sti_priv *p = cs_to_em_sti(cs); 206 207 return em_sti_start(p, USER_CLOCKSOURCE); 208 } 209 210 static void em_sti_clocksource_disable(struct clocksource *cs) 211 { 212 em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE); 213 } 214 215 static void em_sti_clocksource_resume(struct clocksource *cs) 216 { 217 em_sti_clocksource_enable(cs); 218 } 219 220 static int em_sti_register_clocksource(struct em_sti_priv *p) 221 { 222 struct clocksource *cs = &p->cs; 223 224 cs->name = dev_name(&p->pdev->dev); 225 cs->rating = 200; 226 cs->read = em_sti_clocksource_read; 227 cs->enable = em_sti_clocksource_enable; 228 cs->disable = em_sti_clocksource_disable; 229 cs->suspend = em_sti_clocksource_disable; 230 cs->resume = em_sti_clocksource_resume; 231 cs->mask = CLOCKSOURCE_MASK(48); 232 cs->flags = CLOCK_SOURCE_IS_CONTINUOUS; 233 234 dev_info(&p->pdev->dev, "used as clock source\n"); 235 236 clocksource_register_hz(cs, p->rate); 237 return 0; 238 } 239 240 static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced) 241 { 242 return container_of(ced, struct em_sti_priv, ced); 243 } 244 245 static int em_sti_clock_event_shutdown(struct clock_event_device *ced) 246 { 247 struct em_sti_priv *p = ced_to_em_sti(ced); 248 em_sti_stop(p, USER_CLOCKEVENT); 249 return 0; 250 } 251 252 static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced) 253 { 254 struct em_sti_priv *p = ced_to_em_sti(ced); 255 256 dev_info(&p->pdev->dev, "used for oneshot clock events\n"); 257 em_sti_start(p, USER_CLOCKEVENT); 258 return 0; 259 } 260 261 static int em_sti_clock_event_next(unsigned long delta, 262 struct clock_event_device *ced) 263 { 264 struct em_sti_priv *p = ced_to_em_sti(ced); 265 u64 next; 266 int safe; 267 268 next = em_sti_set_next(p, em_sti_count(p) + delta); 269 safe = em_sti_count(p) < (next - 1); 270 271 return !safe; 272 } 273 274 static void em_sti_register_clockevent(struct em_sti_priv *p) 275 { 276 struct clock_event_device *ced = &p->ced; 277 278 ced->name = dev_name(&p->pdev->dev); 279 ced->features = CLOCK_EVT_FEAT_ONESHOT; 280 ced->rating = 200; 281 ced->cpumask = cpu_possible_mask; 282 ced->set_next_event = em_sti_clock_event_next; 283 ced->set_state_shutdown = em_sti_clock_event_shutdown; 284 ced->set_state_oneshot = em_sti_clock_event_set_oneshot; 285 286 dev_info(&p->pdev->dev, "used for clock events\n"); 287 288 clockevents_config_and_register(ced, p->rate, 2, 0xffffffff); 289 } 290 291 static int em_sti_probe(struct platform_device *pdev) 292 { 293 struct em_sti_priv *p; 294 struct resource *res; 295 int irq; 296 int ret; 297 298 p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL); 299 if (p == NULL) 300 return -ENOMEM; 301 302 p->pdev = pdev; 303 platform_set_drvdata(pdev, p); 304 305 irq = platform_get_irq(pdev, 0); 306 if (irq < 0) { 307 dev_err(&pdev->dev, "failed to get irq\n"); 308 return irq; 309 } 310 311 /* map memory, let base point to the STI instance */ 312 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 313 p->base = devm_ioremap_resource(&pdev->dev, res); 314 if (IS_ERR(p->base)) 315 return PTR_ERR(p->base); 316 317 ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt, 318 IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, 319 dev_name(&pdev->dev), p); 320 if (ret) { 321 dev_err(&pdev->dev, "failed to request low IRQ\n"); 322 return ret; 323 } 324 325 /* get hold of clock */ 326 p->clk = devm_clk_get(&pdev->dev, "sclk"); 327 if (IS_ERR(p->clk)) { 328 dev_err(&pdev->dev, "cannot get clock\n"); 329 return PTR_ERR(p->clk); 330 } 331 332 ret = clk_prepare(p->clk); 333 if (ret < 0) { 334 dev_err(&pdev->dev, "cannot prepare clock\n"); 335 return ret; 336 } 337 338 ret = clk_enable(p->clk); 339 if (ret < 0) { 340 dev_err(&p->pdev->dev, "cannot enable clock\n"); 341 clk_unprepare(p->clk); 342 return ret; 343 } 344 p->rate = clk_get_rate(p->clk); 345 clk_disable(p->clk); 346 347 raw_spin_lock_init(&p->lock); 348 em_sti_register_clockevent(p); 349 em_sti_register_clocksource(p); 350 return 0; 351 } 352 353 static int em_sti_remove(struct platform_device *pdev) 354 { 355 return -EBUSY; /* cannot unregister clockevent and clocksource */ 356 } 357 358 static const struct of_device_id em_sti_dt_ids[] = { 359 { .compatible = "renesas,em-sti", }, 360 {}, 361 }; 362 MODULE_DEVICE_TABLE(of, em_sti_dt_ids); 363 364 static struct platform_driver em_sti_device_driver = { 365 .probe = em_sti_probe, 366 .remove = em_sti_remove, 367 .driver = { 368 .name = "em_sti", 369 .of_match_table = em_sti_dt_ids, 370 } 371 }; 372 373 static int __init em_sti_init(void) 374 { 375 return platform_driver_register(&em_sti_device_driver); 376 } 377 378 static void __exit em_sti_exit(void) 379 { 380 platform_driver_unregister(&em_sti_device_driver); 381 } 382 383 subsys_initcall(em_sti_init); 384 module_exit(em_sti_exit); 385 386 MODULE_AUTHOR("Magnus Damm"); 387 MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver"); 388 MODULE_LICENSE("GPL v2"); 389