1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Emma Mobile Timer Support - STI 4 * 5 * Copyright (C) 2012 Magnus Damm 6 */ 7 8 #include <linux/init.h> 9 #include <linux/platform_device.h> 10 #include <linux/spinlock.h> 11 #include <linux/interrupt.h> 12 #include <linux/ioport.h> 13 #include <linux/io.h> 14 #include <linux/clk.h> 15 #include <linux/irq.h> 16 #include <linux/err.h> 17 #include <linux/delay.h> 18 #include <linux/clocksource.h> 19 #include <linux/clockchips.h> 20 #include <linux/slab.h> 21 #include <linux/module.h> 22 23 enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; 24 25 struct em_sti_priv { 26 void __iomem *base; 27 struct clk *clk; 28 struct platform_device *pdev; 29 unsigned int active[USER_NR]; 30 unsigned long rate; 31 raw_spinlock_t lock; 32 struct clock_event_device ced; 33 struct clocksource cs; 34 }; 35 36 #define STI_CONTROL 0x00 37 #define STI_COMPA_H 0x10 38 #define STI_COMPA_L 0x14 39 #define STI_COMPB_H 0x18 40 #define STI_COMPB_L 0x1c 41 #define STI_COUNT_H 0x20 42 #define STI_COUNT_L 0x24 43 #define STI_COUNT_RAW_H 0x28 44 #define STI_COUNT_RAW_L 0x2c 45 #define STI_SET_H 0x30 46 #define STI_SET_L 0x34 47 #define STI_INTSTATUS 0x40 48 #define STI_INTRAWSTATUS 0x44 49 #define STI_INTENSET 0x48 50 #define STI_INTENCLR 0x4c 51 #define STI_INTFFCLR 0x50 52 53 static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) 54 { 55 return ioread32(p->base + offs); 56 } 57 58 static inline void em_sti_write(struct em_sti_priv *p, int offs, 59 unsigned long value) 60 { 61 iowrite32(value, p->base + offs); 62 } 63 64 static int em_sti_enable(struct em_sti_priv *p) 65 { 66 int ret; 67 68 /* enable clock */ 69 ret = clk_enable(p->clk); 70 if (ret) { 71 dev_err(&p->pdev->dev, "cannot enable clock\n"); 72 return ret; 73 } 74 75 /* reset the counter */ 76 em_sti_write(p, STI_SET_H, 0x40000000); 77 em_sti_write(p, STI_SET_L, 0x00000000); 78 79 /* mask and clear pending interrupts */ 80 em_sti_write(p, STI_INTENCLR, 3); 81 em_sti_write(p, STI_INTFFCLR, 3); 82 83 /* enable updates of counter registers */ 84 em_sti_write(p, STI_CONTROL, 1); 85 86 return 0; 87 } 88 89 static void em_sti_disable(struct em_sti_priv *p) 90 { 91 /* mask interrupts */ 92 em_sti_write(p, STI_INTENCLR, 3); 93 94 /* stop clock */ 95 clk_disable(p->clk); 96 } 97 98 static u64 em_sti_count(struct em_sti_priv *p) 99 { 100 u64 ticks; 101 unsigned long flags; 102 103 /* the STI hardware buffers the 48-bit count, but to 104 * break it out into two 32-bit access the registers 105 * must be accessed in a certain order. 106 * Always read STI_COUNT_H before STI_COUNT_L. 107 */ 108 raw_spin_lock_irqsave(&p->lock, flags); 109 ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32; 110 ticks |= em_sti_read(p, STI_COUNT_L); 111 raw_spin_unlock_irqrestore(&p->lock, flags); 112 113 return ticks; 114 } 115 116 static u64 em_sti_set_next(struct em_sti_priv *p, u64 next) 117 { 118 unsigned long flags; 119 120 raw_spin_lock_irqsave(&p->lock, flags); 121 122 /* mask compare A interrupt */ 123 em_sti_write(p, STI_INTENCLR, 1); 124 125 /* update compare A value */ 126 em_sti_write(p, STI_COMPA_H, next >> 32); 127 em_sti_write(p, STI_COMPA_L, next & 0xffffffff); 128 129 /* clear compare A interrupt source */ 130 em_sti_write(p, STI_INTFFCLR, 1); 131 132 /* unmask compare A interrupt */ 133 em_sti_write(p, STI_INTENSET, 1); 134 135 raw_spin_unlock_irqrestore(&p->lock, flags); 136 137 return next; 138 } 139 140 static irqreturn_t em_sti_interrupt(int irq, void *dev_id) 141 { 142 struct em_sti_priv *p = dev_id; 143 144 p->ced.event_handler(&p->ced); 145 return IRQ_HANDLED; 146 } 147 148 static int em_sti_start(struct em_sti_priv *p, unsigned int user) 149 { 150 unsigned long flags; 151 int used_before; 152 int ret = 0; 153 154 raw_spin_lock_irqsave(&p->lock, flags); 155 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; 156 if (!used_before) 157 ret = em_sti_enable(p); 158 159 if (!ret) 160 p->active[user] = 1; 161 raw_spin_unlock_irqrestore(&p->lock, flags); 162 163 return ret; 164 } 165 166 static void em_sti_stop(struct em_sti_priv *p, unsigned int user) 167 { 168 unsigned long flags; 169 int used_before, used_after; 170 171 raw_spin_lock_irqsave(&p->lock, flags); 172 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; 173 p->active[user] = 0; 174 used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; 175 176 if (used_before && !used_after) 177 em_sti_disable(p); 178 raw_spin_unlock_irqrestore(&p->lock, flags); 179 } 180 181 static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) 182 { 183 return container_of(cs, struct em_sti_priv, cs); 184 } 185 186 static u64 em_sti_clocksource_read(struct clocksource *cs) 187 { 188 return em_sti_count(cs_to_em_sti(cs)); 189 } 190 191 static int em_sti_clocksource_enable(struct clocksource *cs) 192 { 193 struct em_sti_priv *p = cs_to_em_sti(cs); 194 195 return em_sti_start(p, USER_CLOCKSOURCE); 196 } 197 198 static void em_sti_clocksource_disable(struct clocksource *cs) 199 { 200 em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE); 201 } 202 203 static void em_sti_clocksource_resume(struct clocksource *cs) 204 { 205 em_sti_clocksource_enable(cs); 206 } 207 208 static int em_sti_register_clocksource(struct em_sti_priv *p) 209 { 210 struct clocksource *cs = &p->cs; 211 212 cs->name = dev_name(&p->pdev->dev); 213 cs->rating = 200; 214 cs->read = em_sti_clocksource_read; 215 cs->enable = em_sti_clocksource_enable; 216 cs->disable = em_sti_clocksource_disable; 217 cs->suspend = em_sti_clocksource_disable; 218 cs->resume = em_sti_clocksource_resume; 219 cs->mask = CLOCKSOURCE_MASK(48); 220 cs->flags = CLOCK_SOURCE_IS_CONTINUOUS; 221 222 dev_info(&p->pdev->dev, "used as clock source\n"); 223 224 clocksource_register_hz(cs, p->rate); 225 return 0; 226 } 227 228 static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced) 229 { 230 return container_of(ced, struct em_sti_priv, ced); 231 } 232 233 static int em_sti_clock_event_shutdown(struct clock_event_device *ced) 234 { 235 struct em_sti_priv *p = ced_to_em_sti(ced); 236 em_sti_stop(p, USER_CLOCKEVENT); 237 return 0; 238 } 239 240 static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced) 241 { 242 struct em_sti_priv *p = ced_to_em_sti(ced); 243 244 dev_info(&p->pdev->dev, "used for oneshot clock events\n"); 245 em_sti_start(p, USER_CLOCKEVENT); 246 return 0; 247 } 248 249 static int em_sti_clock_event_next(unsigned long delta, 250 struct clock_event_device *ced) 251 { 252 struct em_sti_priv *p = ced_to_em_sti(ced); 253 u64 next; 254 int safe; 255 256 next = em_sti_set_next(p, em_sti_count(p) + delta); 257 safe = em_sti_count(p) < (next - 1); 258 259 return !safe; 260 } 261 262 static void em_sti_register_clockevent(struct em_sti_priv *p) 263 { 264 struct clock_event_device *ced = &p->ced; 265 266 ced->name = dev_name(&p->pdev->dev); 267 ced->features = CLOCK_EVT_FEAT_ONESHOT; 268 ced->rating = 200; 269 ced->cpumask = cpu_possible_mask; 270 ced->set_next_event = em_sti_clock_event_next; 271 ced->set_state_shutdown = em_sti_clock_event_shutdown; 272 ced->set_state_oneshot = em_sti_clock_event_set_oneshot; 273 274 dev_info(&p->pdev->dev, "used for clock events\n"); 275 276 clockevents_config_and_register(ced, p->rate, 2, 0xffffffff); 277 } 278 279 static int em_sti_probe(struct platform_device *pdev) 280 { 281 struct em_sti_priv *p; 282 int irq, ret; 283 284 p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL); 285 if (p == NULL) 286 return -ENOMEM; 287 288 p->pdev = pdev; 289 platform_set_drvdata(pdev, p); 290 291 irq = platform_get_irq(pdev, 0); 292 if (irq < 0) 293 return irq; 294 295 /* map memory, let base point to the STI instance */ 296 p->base = devm_platform_ioremap_resource(pdev, 0); 297 if (IS_ERR(p->base)) 298 return PTR_ERR(p->base); 299 300 ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt, 301 IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, 302 dev_name(&pdev->dev), p); 303 if (ret) { 304 dev_err(&pdev->dev, "failed to request low IRQ\n"); 305 return ret; 306 } 307 308 /* get hold of clock */ 309 p->clk = devm_clk_get(&pdev->dev, "sclk"); 310 if (IS_ERR(p->clk)) { 311 dev_err(&pdev->dev, "cannot get clock\n"); 312 return PTR_ERR(p->clk); 313 } 314 315 ret = clk_prepare(p->clk); 316 if (ret < 0) { 317 dev_err(&pdev->dev, "cannot prepare clock\n"); 318 return ret; 319 } 320 321 ret = clk_enable(p->clk); 322 if (ret < 0) { 323 dev_err(&p->pdev->dev, "cannot enable clock\n"); 324 clk_unprepare(p->clk); 325 return ret; 326 } 327 p->rate = clk_get_rate(p->clk); 328 clk_disable(p->clk); 329 330 raw_spin_lock_init(&p->lock); 331 em_sti_register_clockevent(p); 332 em_sti_register_clocksource(p); 333 return 0; 334 } 335 336 static int em_sti_remove(struct platform_device *pdev) 337 { 338 return -EBUSY; /* cannot unregister clockevent and clocksource */ 339 } 340 341 static const struct of_device_id em_sti_dt_ids[] = { 342 { .compatible = "renesas,em-sti", }, 343 {}, 344 }; 345 MODULE_DEVICE_TABLE(of, em_sti_dt_ids); 346 347 static struct platform_driver em_sti_device_driver = { 348 .probe = em_sti_probe, 349 .remove = em_sti_remove, 350 .driver = { 351 .name = "em_sti", 352 .of_match_table = em_sti_dt_ids, 353 } 354 }; 355 356 static int __init em_sti_init(void) 357 { 358 return platform_driver_register(&em_sti_device_driver); 359 } 360 361 static void __exit em_sti_exit(void) 362 { 363 platform_driver_unregister(&em_sti_device_driver); 364 } 365 366 subsys_initcall(em_sti_init); 367 module_exit(em_sti_exit); 368 369 MODULE_AUTHOR("Magnus Damm"); 370 MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver"); 371 MODULE_LICENSE("GPL v2"); 372