| 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | #include <linux/init.h> |
| 3 | #include <linux/clocksource.h> |
| 4 | #include <linux/clockchips.h> |
| 5 | #include <linux/interrupt.h> |
| 6 | #include <linux/irq.h> |
| 7 | |
| 8 | #include <linux/clk.h> |
| 9 | #include <linux/err.h> |
| 10 | #include <linux/ioport.h> |
| 11 | #include <linux/io.h> |
| 12 | #include <linux/platform_device.h> |
| 13 | #include <linux/syscore_ops.h> |
| 14 | #include <linux/atmel_tc.h> |
| 15 | |
| 16 | |
| 17 | /* |
| 18 | * We're configured to use a specific TC block, one that's not hooked |
| 19 | * up to external hardware, to provide a time solution: |
| 20 | * |
| 21 | * - Two channels combine to create a free-running 32 bit counter |
| 22 | * with a base rate of 5+ MHz, packaged as a clocksource (with |
| 23 | * resolution better than 200 nsec). |
| 24 | * - Some chips support 32 bit counter. A single channel is used for |
| 25 | * this 32 bit free-running counter. the second channel is not used. |
| 26 | * |
| 27 | * - The third channel may be used to provide a 16-bit clockevent |
| 28 | * source, used in either periodic or oneshot mode. This runs |
| 29 | * at 32 KiHZ, and can handle delays of up to two seconds. |
| 30 | * |
| 31 | * A boot clocksource and clockevent source are also currently needed, |
| 32 | * unless the relevant platforms (ARM/AT91, AVR32/AT32) are changed so |
| 33 | * this code can be used when init_timers() is called, well before most |
| 34 | * devices are set up. (Some low end AT91 parts, which can run uClinux, |
| 35 | * have only the timers in one TC block... they currently don't support |
| 36 | * the tclib code, because of that initialization issue.) |
| 37 | * |
| 38 | * REVISIT behavior during system suspend states... we should disable |
| 39 | * all clocks and save the power. Easily done for clockevent devices, |
| 40 | * but clocksources won't necessarily get the needed notifications. |
| 41 | * For deeper system sleep states, this will be mandatory... |
| 42 | */ |
| 43 | |
| 44 | static void __iomem *tcaddr; |
| 45 | static struct |
| 46 | { |
| 47 | u32 cmr; |
| 48 | u32 imr; |
| 49 | u32 rc; |
| 50 | bool clken; |
| 51 | } tcb_cache[3]; |
| 52 | static u32 bmr_cache; |
| 53 | |
| 54 | static u64 tc_get_cycles(struct clocksource *cs) |
| 55 | { |
| 56 | unsigned long flags; |
| 57 | u32 lower, upper; |
| 58 | |
| 59 | raw_local_irq_save(flags); |
| 60 | do { |
| 61 | upper = readl_relaxed(tcaddr + ATMEL_TC_REG(1, CV)); |
| 62 | lower = readl_relaxed(tcaddr + ATMEL_TC_REG(0, CV)); |
| 63 | } while (upper != readl_relaxed(tcaddr + ATMEL_TC_REG(1, CV))); |
| 64 | |
| 65 | raw_local_irq_restore(flags); |
| 66 | return (upper << 16) | lower; |
| 67 | } |
| 68 | |
| 69 | static u64 tc_get_cycles32(struct clocksource *cs) |
| 70 | { |
| 71 | return readl_relaxed(tcaddr + ATMEL_TC_REG(0, CV)); |
| 72 | } |
| 73 | |
| 74 | void tc_clksrc_suspend(struct clocksource *cs) |
| 75 | { |
| 76 | int i; |
| 77 | |
| 78 | for (i = 0; i < ARRAY_SIZE(tcb_cache); i++) { |
| 79 | tcb_cache[i].cmr = readl(tcaddr + ATMEL_TC_REG(i, CMR)); |
| 80 | tcb_cache[i].imr = readl(tcaddr + ATMEL_TC_REG(i, IMR)); |
| 81 | tcb_cache[i].rc = readl(tcaddr + ATMEL_TC_REG(i, RC)); |
| 82 | tcb_cache[i].clken = !!(readl(tcaddr + ATMEL_TC_REG(i, SR)) & |
| 83 | ATMEL_TC_CLKSTA); |
| 84 | } |
| 85 | |
| 86 | bmr_cache = readl(tcaddr + ATMEL_TC_BMR); |
| 87 | } |
| 88 | |
| 89 | void tc_clksrc_resume(struct clocksource *cs) |
| 90 | { |
| 91 | int i; |
| 92 | |
| 93 | for (i = 0; i < ARRAY_SIZE(tcb_cache); i++) { |
| 94 | /* Restore registers for the channel, RA and RB are not used */ |
| 95 | writel(tcb_cache[i].cmr, tcaddr + ATMEL_TC_REG(i, CMR)); |
| 96 | writel(tcb_cache[i].rc, tcaddr + ATMEL_TC_REG(i, RC)); |
| 97 | writel(0, tcaddr + ATMEL_TC_REG(i, RA)); |
| 98 | writel(0, tcaddr + ATMEL_TC_REG(i, RB)); |
| 99 | /* Disable all the interrupts */ |
| 100 | writel(0xff, tcaddr + ATMEL_TC_REG(i, IDR)); |
| 101 | /* Reenable interrupts that were enabled before suspending */ |
| 102 | writel(tcb_cache[i].imr, tcaddr + ATMEL_TC_REG(i, IER)); |
| 103 | /* Start the clock if it was used */ |
| 104 | if (tcb_cache[i].clken) |
| 105 | writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(i, CCR)); |
| 106 | } |
| 107 | |
| 108 | /* Dual channel, chain channels */ |
| 109 | writel(bmr_cache, tcaddr + ATMEL_TC_BMR); |
| 110 | /* Finally, trigger all the channels*/ |
| 111 | writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); |
| 112 | } |
| 113 | |
| 114 | static struct clocksource clksrc = { |
| 115 | .name = "tcb_clksrc", |
| 116 | .rating = 200, |
| 117 | .read = tc_get_cycles, |
| 118 | .mask = CLOCKSOURCE_MASK(32), |
| 119 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| 120 | .suspend = tc_clksrc_suspend, |
| 121 | .resume = tc_clksrc_resume, |
| 122 | }; |
| 123 | |
| 124 | #ifdef CONFIG_GENERIC_CLOCKEVENTS |
| 125 | |
| 126 | struct tc_clkevt_device { |
| 127 | struct clock_event_device clkevt; |
| 128 | struct clk *clk; |
| 129 | void __iomem *regs; |
| 130 | }; |
| 131 | |
| 132 | static struct tc_clkevt_device *to_tc_clkevt(struct clock_event_device *clkevt) |
| 133 | { |
| 134 | return container_of(clkevt, struct tc_clkevt_device, clkevt); |
| 135 | } |
| 136 | |
| 137 | /* For now, we always use the 32K clock ... this optimizes for NO_HZ, |
| 138 | * because using one of the divided clocks would usually mean the |
| 139 | * tick rate can never be less than several dozen Hz (vs 0.5 Hz). |
| 140 | * |
| 141 | * A divided clock could be good for high resolution timers, since |
| 142 | * 30.5 usec resolution can seem "low". |
| 143 | */ |
| 144 | static u32 timer_clock; |
| 145 | |
| 146 | static int tc_shutdown(struct clock_event_device *d) |
| 147 | { |
| 148 | struct tc_clkevt_device *tcd = to_tc_clkevt(d); |
| 149 | void __iomem *regs = tcd->regs; |
| 150 | |
| 151 | writel(0xff, regs + ATMEL_TC_REG(2, IDR)); |
| 152 | writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR)); |
| 153 | if (!clockevent_state_detached(d)) |
| 154 | clk_disable(tcd->clk); |
| 155 | |
| 156 | return 0; |
| 157 | } |
| 158 | |
| 159 | static int tc_set_oneshot(struct clock_event_device *d) |
| 160 | { |
| 161 | struct tc_clkevt_device *tcd = to_tc_clkevt(d); |
| 162 | void __iomem *regs = tcd->regs; |
| 163 | |
| 164 | if (clockevent_state_oneshot(d) || clockevent_state_periodic(d)) |
| 165 | tc_shutdown(d); |
| 166 | |
| 167 | clk_enable(tcd->clk); |
| 168 | |
| 169 | /* slow clock, count up to RC, then irq and stop */ |
| 170 | writel(timer_clock | ATMEL_TC_CPCSTOP | ATMEL_TC_WAVE | |
| 171 | ATMEL_TC_WAVESEL_UP_AUTO, regs + ATMEL_TC_REG(2, CMR)); |
| 172 | writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); |
| 173 | |
| 174 | /* set_next_event() configures and starts the timer */ |
| 175 | return 0; |
| 176 | } |
| 177 | |
| 178 | static int tc_set_periodic(struct clock_event_device *d) |
| 179 | { |
| 180 | struct tc_clkevt_device *tcd = to_tc_clkevt(d); |
| 181 | void __iomem *regs = tcd->regs; |
| 182 | |
| 183 | if (clockevent_state_oneshot(d) || clockevent_state_periodic(d)) |
| 184 | tc_shutdown(d); |
| 185 | |
| 186 | /* By not making the gentime core emulate periodic mode on top |
| 187 | * of oneshot, we get lower overhead and improved accuracy. |
| 188 | */ |
| 189 | clk_enable(tcd->clk); |
| 190 | |
| 191 | /* slow clock, count up to RC, then irq and restart */ |
| 192 | writel(timer_clock | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO, |
| 193 | regs + ATMEL_TC_REG(2, CMR)); |
| 194 | writel((32768 + HZ / 2) / HZ, tcaddr + ATMEL_TC_REG(2, RC)); |
| 195 | |
| 196 | /* Enable clock and interrupts on RC compare */ |
| 197 | writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); |
| 198 | |
| 199 | /* go go gadget! */ |
| 200 | writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, regs + |
| 201 | ATMEL_TC_REG(2, CCR)); |
| 202 | return 0; |
| 203 | } |
| 204 | |
| 205 | static int tc_next_event(unsigned long delta, struct clock_event_device *d) |
| 206 | { |
| 207 | writel_relaxed(delta, tcaddr + ATMEL_TC_REG(2, RC)); |
| 208 | |
| 209 | /* go go gadget! */ |
| 210 | writel_relaxed(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, |
| 211 | tcaddr + ATMEL_TC_REG(2, CCR)); |
| 212 | return 0; |
| 213 | } |
| 214 | |
| 215 | static struct tc_clkevt_device clkevt = { |
| 216 | .clkevt = { |
| 217 | .name = "tc_clkevt", |
| 218 | .features = CLOCK_EVT_FEAT_PERIODIC | |
| 219 | CLOCK_EVT_FEAT_ONESHOT, |
| 220 | /* Should be lower than at91rm9200's system timer */ |
| 221 | .rating = 125, |
| 222 | .set_next_event = tc_next_event, |
| 223 | .set_state_shutdown = tc_shutdown, |
| 224 | .set_state_periodic = tc_set_periodic, |
| 225 | .set_state_oneshot = tc_set_oneshot, |
| 226 | }, |
| 227 | }; |
| 228 | |
| 229 | static irqreturn_t ch2_irq(int irq, void *handle) |
| 230 | { |
| 231 | struct tc_clkevt_device *dev = handle; |
| 232 | unsigned int sr; |
| 233 | |
| 234 | sr = readl_relaxed(dev->regs + ATMEL_TC_REG(2, SR)); |
| 235 | if (sr & ATMEL_TC_CPCS) { |
| 236 | dev->clkevt.event_handler(&dev->clkevt); |
| 237 | return IRQ_HANDLED; |
| 238 | } |
| 239 | |
| 240 | return IRQ_NONE; |
| 241 | } |
| 242 | |
| 243 | static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) |
| 244 | { |
| 245 | int ret; |
| 246 | struct clk *t2_clk = tc->clk[2]; |
| 247 | int irq = tc->irq[2]; |
| 248 | |
| 249 | ret = clk_prepare_enable(tc->slow_clk); |
| 250 | if (ret) |
| 251 | return ret; |
| 252 | |
| 253 | /* try to enable t2 clk to avoid future errors in mode change */ |
| 254 | ret = clk_prepare_enable(t2_clk); |
| 255 | if (ret) { |
| 256 | clk_disable_unprepare(tc->slow_clk); |
| 257 | return ret; |
| 258 | } |
| 259 | |
| 260 | clk_disable(t2_clk); |
| 261 | |
| 262 | clkevt.regs = tc->regs; |
| 263 | clkevt.clk = t2_clk; |
| 264 | |
| 265 | timer_clock = clk32k_divisor_idx; |
| 266 | |
| 267 | clkevt.clkevt.cpumask = cpumask_of(0); |
| 268 | |
| 269 | ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt); |
| 270 | if (ret) { |
| 271 | clk_unprepare(t2_clk); |
| 272 | clk_disable_unprepare(tc->slow_clk); |
| 273 | return ret; |
| 274 | } |
| 275 | |
| 276 | clockevents_config_and_register(&clkevt.clkevt, 32768, 1, 0xffff); |
| 277 | |
| 278 | return ret; |
| 279 | } |
| 280 | |
| 281 | #else /* !CONFIG_GENERIC_CLOCKEVENTS */ |
| 282 | |
| 283 | static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) |
| 284 | { |
| 285 | /* NOTHING */ |
| 286 | return 0; |
| 287 | } |
| 288 | |
| 289 | #endif |
| 290 | |
| 291 | static void __init tcb_setup_dual_chan(struct atmel_tc *tc, int mck_divisor_idx) |
| 292 | { |
| 293 | /* channel 0: waveform mode, input mclk/8, clock TIOA0 on overflow */ |
| 294 | writel(mck_divisor_idx /* likely divide-by-8 */ |
| 295 | | ATMEL_TC_WAVE |
| 296 | | ATMEL_TC_WAVESEL_UP /* free-run */ |
| 297 | | ATMEL_TC_ACPA_SET /* TIOA0 rises at 0 */ |
| 298 | | ATMEL_TC_ACPC_CLEAR, /* (duty cycle 50%) */ |
| 299 | tcaddr + ATMEL_TC_REG(0, CMR)); |
| 300 | writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA)); |
| 301 | writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC)); |
| 302 | writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ |
| 303 | writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); |
| 304 | |
| 305 | /* channel 1: waveform mode, input TIOA0 */ |
| 306 | writel(ATMEL_TC_XC1 /* input: TIOA0 */ |
| 307 | | ATMEL_TC_WAVE |
| 308 | | ATMEL_TC_WAVESEL_UP, /* free-run */ |
| 309 | tcaddr + ATMEL_TC_REG(1, CMR)); |
| 310 | writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR)); /* no irqs */ |
| 311 | writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR)); |
| 312 | |
| 313 | /* chain channel 0 to channel 1*/ |
| 314 | writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR); |
| 315 | /* then reset all the timers */ |
| 316 | writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); |
| 317 | } |
| 318 | |
| 319 | static void __init tcb_setup_single_chan(struct atmel_tc *tc, int mck_divisor_idx) |
| 320 | { |
| 321 | /* channel 0: waveform mode, input mclk/8 */ |
| 322 | writel(mck_divisor_idx /* likely divide-by-8 */ |
| 323 | | ATMEL_TC_WAVE |
| 324 | | ATMEL_TC_WAVESEL_UP, /* free-run */ |
| 325 | tcaddr + ATMEL_TC_REG(0, CMR)); |
| 326 | writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ |
| 327 | writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); |
| 328 | |
| 329 | /* then reset all the timers */ |
| 330 | writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); |
| 331 | } |
| 332 | |
| 333 | static int __init tcb_clksrc_init(void) |
| 334 | { |
| 335 | static char bootinfo[] __initdata |
| 336 | = KERN_DEBUG "%s: tc%d at %d.%03d MHz\n"; |
| 337 | |
| 338 | struct platform_device *pdev; |
| 339 | struct atmel_tc *tc; |
| 340 | struct clk *t0_clk; |
| 341 | u32 rate, divided_rate = 0; |
| 342 | int best_divisor_idx = -1; |
| 343 | int clk32k_divisor_idx = -1; |
| 344 | int i; |
| 345 | int ret; |
| 346 | |
| 347 | tc = atmel_tc_alloc(CONFIG_ATMEL_TCB_CLKSRC_BLOCK); |
| 348 | if (!tc) { |
| 349 | pr_debug("can't alloc TC for clocksource\n"); |
| 350 | return -ENODEV; |
| 351 | } |
| 352 | tcaddr = tc->regs; |
| 353 | pdev = tc->pdev; |
| 354 | |
| 355 | t0_clk = tc->clk[0]; |
| 356 | ret = clk_prepare_enable(t0_clk); |
| 357 | if (ret) { |
| 358 | pr_debug("can't enable T0 clk\n"); |
| 359 | goto err_free_tc; |
| 360 | } |
| 361 | |
| 362 | /* How fast will we be counting? Pick something over 5 MHz. */ |
| 363 | rate = (u32) clk_get_rate(t0_clk); |
| 364 | for (i = 0; i < 5; i++) { |
| 365 | unsigned divisor = atmel_tc_divisors[i]; |
| 366 | unsigned tmp; |
| 367 | |
| 368 | /* remember 32 KiHz clock for later */ |
| 369 | if (!divisor) { |
| 370 | clk32k_divisor_idx = i; |
| 371 | continue; |
| 372 | } |
| 373 | |
| 374 | tmp = rate / divisor; |
| 375 | pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp); |
| 376 | if (best_divisor_idx > 0) { |
| 377 | if (tmp < 5 * 1000 * 1000) |
| 378 | continue; |
| 379 | } |
| 380 | divided_rate = tmp; |
| 381 | best_divisor_idx = i; |
| 382 | } |
| 383 | |
| 384 | |
| 385 | printk(bootinfo, clksrc.name, CONFIG_ATMEL_TCB_CLKSRC_BLOCK, |
| 386 | divided_rate / 1000000, |
| 387 | ((divided_rate % 1000000) + 500) / 1000); |
| 388 | |
| 389 | if (tc->tcb_config && tc->tcb_config->counter_width == 32) { |
| 390 | /* use apropriate function to read 32 bit counter */ |
| 391 | clksrc.read = tc_get_cycles32; |
| 392 | /* setup ony channel 0 */ |
| 393 | tcb_setup_single_chan(tc, best_divisor_idx); |
| 394 | } else { |
| 395 | /* tclib will give us three clocks no matter what the |
| 396 | * underlying platform supports. |
| 397 | */ |
| 398 | ret = clk_prepare_enable(tc->clk[1]); |
| 399 | if (ret) { |
| 400 | pr_debug("can't enable T1 clk\n"); |
| 401 | goto err_disable_t0; |
| 402 | } |
| 403 | /* setup both channel 0 & 1 */ |
| 404 | tcb_setup_dual_chan(tc, best_divisor_idx); |
| 405 | } |
| 406 | |
| 407 | /* and away we go! */ |
| 408 | ret = clocksource_register_hz(&clksrc, divided_rate); |
| 409 | if (ret) |
| 410 | goto err_disable_t1; |
| 411 | |
| 412 | /* channel 2: periodic and oneshot timer support */ |
| 413 | ret = setup_clkevents(tc, clk32k_divisor_idx); |
| 414 | if (ret) |
| 415 | goto err_unregister_clksrc; |
| 416 | |
| 417 | return 0; |
| 418 | |
| 419 | err_unregister_clksrc: |
| 420 | clocksource_unregister(&clksrc); |
| 421 | |
| 422 | err_disable_t1: |
| 423 | if (!tc->tcb_config || tc->tcb_config->counter_width != 32) |
| 424 | clk_disable_unprepare(tc->clk[1]); |
| 425 | |
| 426 | err_disable_t0: |
| 427 | clk_disable_unprepare(t0_clk); |
| 428 | |
| 429 | err_free_tc: |
| 430 | atmel_tc_free(tc); |
| 431 | return ret; |
| 432 | } |
| 433 | arch_initcall(tcb_clksrc_init); |