1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2015 Neil Armstrong <narmstrong@baylibre.com> 4 * Copyright (c) 2014 Joachim Eastwood <manabian@gmail.com> 5 * Copyright (c) 2012 NeilBrown <neilb@suse.de> 6 * Heavily based on earlier code which is: 7 * Copyright (c) 2010 Grant Erickson <marathon96@gmail.com> 8 * 9 * Also based on pwm-samsung.c 10 * 11 * Description: 12 * This file is the core OMAP support for the generic, Linux 13 * PWM driver / controller, using the OMAP's dual-mode timers 14 * with a timer counter that goes up. When it overflows it gets 15 * reloaded with the load value and the pwm output goes up. 16 * When counter matches with match register, the output goes down. 17 * Reference Manual: https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf 18 * 19 * Limitations: 20 * - When PWM is stopped, timer counter gets stopped immediately. This 21 * doesn't allow the current PWM period to complete and stops abruptly. 22 * - When PWM is running and changing both duty cycle and period, 23 * we cannot prevent in software that the output might produce 24 * a period with mixed settings. Especially when period/duty_cyle 25 * is updated while the pwm pin is high, current pwm period/duty_cycle 26 * can get updated as below based on the current timer counter: 27 * - period for current cycle = current_period + new period 28 * - duty_cycle for current period = current period + new duty_cycle. 29 * - PWM OMAP DM timer cannot change the polarity when pwm is active. When 30 * user requests a change in polarity when in active state: 31 * - PWM is stopped abruptly(without completing the current cycle) 32 * - Polarity is changed 33 * - A fresh cycle is started. 34 */ 35 36 #include <linux/clk.h> 37 #include <linux/err.h> 38 #include <linux/kernel.h> 39 #include <linux/module.h> 40 #include <linux/mutex.h> 41 #include <linux/of.h> 42 #include <linux/of_platform.h> 43 #include <clocksource/timer-ti-dm.h> 44 #include <linux/platform_data/dmtimer-omap.h> 45 #include <linux/platform_device.h> 46 #include <linux/pm_runtime.h> 47 #include <linux/pwm.h> 48 #include <linux/slab.h> 49 #include <linux/time.h> 50 51 #define DM_TIMER_LOAD_MIN 0xfffffffe 52 #define DM_TIMER_MAX 0xffffffff 53 54 /** 55 * struct pwm_omap_dmtimer_chip - Structure representing a pwm chip 56 * corresponding to omap dmtimer. 57 * @chip: PWM chip structure representing PWM controller 58 * @mutex: Mutex to protect pwm apply state 59 * @dm_timer: Pointer to omap dm timer. 60 * @pdata: Pointer to omap dm timer ops. 61 * @dm_timer_pdev: Pointer to omap dm timer platform device 62 */ 63 struct pwm_omap_dmtimer_chip { 64 struct pwm_chip chip; 65 /* Mutex to protect pwm apply state */ 66 struct mutex mutex; 67 struct omap_dm_timer *dm_timer; 68 const struct omap_dm_timer_ops *pdata; 69 struct platform_device *dm_timer_pdev; 70 }; 71 72 static inline struct pwm_omap_dmtimer_chip * 73 to_pwm_omap_dmtimer_chip(struct pwm_chip *chip) 74 { 75 return container_of(chip, struct pwm_omap_dmtimer_chip, chip); 76 } 77 78 /** 79 * pwm_omap_dmtimer_get_clock_cycles() - Get clock cycles in a time frame 80 * @clk_rate: pwm timer clock rate 81 * @ns: time frame in nano seconds. 82 * 83 * Return number of clock cycles in a given period(ins ns). 84 */ 85 static u32 pwm_omap_dmtimer_get_clock_cycles(unsigned long clk_rate, int ns) 86 { 87 return DIV_ROUND_CLOSEST_ULL((u64)clk_rate * ns, NSEC_PER_SEC); 88 } 89 90 /** 91 * pwm_omap_dmtimer_start() - Start the pwm omap dm timer in pwm mode 92 * @omap: Pointer to pwm omap dm timer chip 93 */ 94 static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap) 95 { 96 /* 97 * According to OMAP 4 TRM section 22.2.4.10 the counter should be 98 * started at 0xFFFFFFFE when overflow and match is used to ensure 99 * that the PWM line is toggled on the first event. 100 * 101 * Note that omap_dm_timer_enable/disable is for register access and 102 * not the timer counter itself. 103 */ 104 omap->pdata->enable(omap->dm_timer); 105 omap->pdata->write_counter(omap->dm_timer, DM_TIMER_LOAD_MIN); 106 omap->pdata->disable(omap->dm_timer); 107 108 omap->pdata->start(omap->dm_timer); 109 } 110 111 /** 112 * pwm_omap_dmtimer_is_enabled() - Detect if the pwm is enabled. 113 * @omap: Pointer to pwm omap dm timer chip 114 * 115 * Return true if pwm is enabled else false. 116 */ 117 static bool pwm_omap_dmtimer_is_enabled(struct pwm_omap_dmtimer_chip *omap) 118 { 119 u32 status; 120 121 status = omap->pdata->get_pwm_status(omap->dm_timer); 122 123 return !!(status & OMAP_TIMER_CTRL_ST); 124 } 125 126 /** 127 * pwm_omap_dmtimer_polarity() - Detect the polarity of pwm. 128 * @omap: Pointer to pwm omap dm timer chip 129 * 130 * Return the polarity of pwm. 131 */ 132 static int pwm_omap_dmtimer_polarity(struct pwm_omap_dmtimer_chip *omap) 133 { 134 u32 status; 135 136 status = omap->pdata->get_pwm_status(omap->dm_timer); 137 138 return !!(status & OMAP_TIMER_CTRL_SCPWM); 139 } 140 141 /** 142 * pwm_omap_dmtimer_config() - Update the configuration of pwm omap dm timer 143 * @chip: Pointer to PWM controller 144 * @pwm: Pointer to PWM channel 145 * @duty_ns: New duty cycle in nano seconds 146 * @period_ns: New period in nano seconds 147 * 148 * Return 0 if successfully changed the period/duty_cycle else appropriate 149 * error. 150 */ 151 static int pwm_omap_dmtimer_config(struct pwm_chip *chip, 152 struct pwm_device *pwm, 153 int duty_ns, int period_ns) 154 { 155 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); 156 u32 period_cycles, duty_cycles; 157 u32 load_value, match_value; 158 unsigned long clk_rate; 159 struct clk *fclk; 160 161 dev_dbg(chip->dev, "requested duty cycle: %d ns, period: %d ns\n", 162 duty_ns, period_ns); 163 164 if (duty_ns == pwm_get_duty_cycle(pwm) && 165 period_ns == pwm_get_period(pwm)) 166 return 0; 167 168 fclk = omap->pdata->get_fclk(omap->dm_timer); 169 if (!fclk) { 170 dev_err(chip->dev, "invalid pmtimer fclk\n"); 171 return -EINVAL; 172 } 173 174 clk_rate = clk_get_rate(fclk); 175 if (!clk_rate) { 176 dev_err(chip->dev, "invalid pmtimer fclk rate\n"); 177 return -EINVAL; 178 } 179 180 dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate); 181 182 /* 183 * Calculate the appropriate load and match values based on the 184 * specified period and duty cycle. The load value determines the 185 * period time and the match value determines the duty time. 186 * 187 * The period lasts for (DM_TIMER_MAX-load_value+1) clock cycles. 188 * Similarly, the active time lasts (match_value-load_value+1) cycles. 189 * The non-active time is the remainder: (DM_TIMER_MAX-match_value) 190 * clock cycles. 191 * 192 * NOTE: It is required that: load_value <= match_value < DM_TIMER_MAX 193 * 194 * References: 195 * OMAP4430/60/70 TRM sections 22.2.4.10 and 22.2.4.11 196 * AM335x Sitara TRM sections 20.1.3.5 and 20.1.3.6 197 */ 198 period_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, period_ns); 199 duty_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, duty_ns); 200 201 if (period_cycles < 2) { 202 dev_info(chip->dev, 203 "period %d ns too short for clock rate %lu Hz\n", 204 period_ns, clk_rate); 205 return -EINVAL; 206 } 207 208 if (duty_cycles < 1) { 209 dev_dbg(chip->dev, 210 "duty cycle %d ns is too short for clock rate %lu Hz\n", 211 duty_ns, clk_rate); 212 dev_dbg(chip->dev, "using minimum of 1 clock cycle\n"); 213 duty_cycles = 1; 214 } else if (duty_cycles >= period_cycles) { 215 dev_dbg(chip->dev, 216 "duty cycle %d ns is too long for period %d ns at clock rate %lu Hz\n", 217 duty_ns, period_ns, clk_rate); 218 dev_dbg(chip->dev, "using maximum of 1 clock cycle less than period\n"); 219 duty_cycles = period_cycles - 1; 220 } 221 222 dev_dbg(chip->dev, "effective duty cycle: %lld ns, period: %lld ns\n", 223 DIV_ROUND_CLOSEST_ULL((u64)NSEC_PER_SEC * duty_cycles, 224 clk_rate), 225 DIV_ROUND_CLOSEST_ULL((u64)NSEC_PER_SEC * period_cycles, 226 clk_rate)); 227 228 load_value = (DM_TIMER_MAX - period_cycles) + 1; 229 match_value = load_value + duty_cycles - 1; 230 231 omap->pdata->set_load(omap->dm_timer, load_value); 232 omap->pdata->set_match(omap->dm_timer, true, match_value); 233 234 dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n", 235 load_value, load_value, match_value, match_value); 236 237 return 0; 238 } 239 240 /** 241 * pwm_omap_dmtimer_set_polarity() - Changes the polarity of the pwm dm timer. 242 * @chip: Pointer to PWM controller 243 * @pwm: Pointer to PWM channel 244 * @polarity: New pwm polarity to be set 245 */ 246 static void pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip, 247 struct pwm_device *pwm, 248 enum pwm_polarity polarity) 249 { 250 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); 251 bool enabled; 252 253 /* Disable the PWM before changing the polarity. */ 254 enabled = pwm_omap_dmtimer_is_enabled(omap); 255 if (enabled) 256 omap->pdata->stop(omap->dm_timer); 257 258 omap->pdata->set_pwm(omap->dm_timer, 259 polarity == PWM_POLARITY_INVERSED, 260 true, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE, 261 true); 262 263 if (enabled) 264 pwm_omap_dmtimer_start(omap); 265 } 266 267 /** 268 * pwm_omap_dmtimer_apply() - Changes the state of the pwm omap dm timer. 269 * @chip: Pointer to PWM controller 270 * @pwm: Pointer to PWM channel 271 * @state: New state to apply 272 * 273 * Return 0 if successfully changed the state else appropriate error. 274 */ 275 static int pwm_omap_dmtimer_apply(struct pwm_chip *chip, 276 struct pwm_device *pwm, 277 const struct pwm_state *state) 278 { 279 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); 280 int ret = 0; 281 282 mutex_lock(&omap->mutex); 283 284 if (pwm_omap_dmtimer_is_enabled(omap) && !state->enabled) { 285 omap->pdata->stop(omap->dm_timer); 286 goto unlock_mutex; 287 } 288 289 if (pwm_omap_dmtimer_polarity(omap) != state->polarity) 290 pwm_omap_dmtimer_set_polarity(chip, pwm, state->polarity); 291 292 ret = pwm_omap_dmtimer_config(chip, pwm, state->duty_cycle, 293 state->period); 294 if (ret) 295 goto unlock_mutex; 296 297 if (!pwm_omap_dmtimer_is_enabled(omap) && state->enabled) { 298 omap->pdata->set_pwm(omap->dm_timer, 299 state->polarity == PWM_POLARITY_INVERSED, 300 true, 301 OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE, 302 true); 303 pwm_omap_dmtimer_start(omap); 304 } 305 306 unlock_mutex: 307 mutex_unlock(&omap->mutex); 308 309 return ret; 310 } 311 312 static const struct pwm_ops pwm_omap_dmtimer_ops = { 313 .apply = pwm_omap_dmtimer_apply, 314 .owner = THIS_MODULE, 315 }; 316 317 static int pwm_omap_dmtimer_probe(struct platform_device *pdev) 318 { 319 struct device_node *np = pdev->dev.of_node; 320 struct dmtimer_platform_data *timer_pdata; 321 const struct omap_dm_timer_ops *pdata; 322 struct platform_device *timer_pdev; 323 struct pwm_omap_dmtimer_chip *omap; 324 struct omap_dm_timer *dm_timer; 325 struct device_node *timer; 326 int ret = 0; 327 u32 v; 328 329 timer = of_parse_phandle(np, "ti,timers", 0); 330 if (!timer) 331 return -ENODEV; 332 333 timer_pdev = of_find_device_by_node(timer); 334 if (!timer_pdev) { 335 dev_err(&pdev->dev, "Unable to find Timer pdev\n"); 336 ret = -ENODEV; 337 goto err_find_timer_pdev; 338 } 339 340 timer_pdata = dev_get_platdata(&timer_pdev->dev); 341 if (!timer_pdata) { 342 dev_dbg(&pdev->dev, 343 "dmtimer pdata structure NULL, deferring probe\n"); 344 ret = -EPROBE_DEFER; 345 goto err_platdata; 346 } 347 348 pdata = timer_pdata->timer_ops; 349 350 if (!pdata || !pdata->request_by_node || 351 !pdata->free || 352 !pdata->enable || 353 !pdata->disable || 354 !pdata->get_fclk || 355 !pdata->start || 356 !pdata->stop || 357 !pdata->set_load || 358 !pdata->set_match || 359 !pdata->set_pwm || 360 !pdata->get_pwm_status || 361 !pdata->set_prescaler || 362 !pdata->write_counter) { 363 dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n"); 364 ret = -EINVAL; 365 goto err_platdata; 366 } 367 368 if (!of_get_property(timer, "ti,timer-pwm", NULL)) { 369 dev_err(&pdev->dev, "Missing ti,timer-pwm capability\n"); 370 ret = -ENODEV; 371 goto err_timer_property; 372 } 373 374 dm_timer = pdata->request_by_node(timer); 375 if (!dm_timer) { 376 ret = -EPROBE_DEFER; 377 goto err_request_timer; 378 } 379 380 omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL); 381 if (!omap) { 382 ret = -ENOMEM; 383 goto err_alloc_omap; 384 } 385 386 omap->pdata = pdata; 387 omap->dm_timer = dm_timer; 388 omap->dm_timer_pdev = timer_pdev; 389 390 /* 391 * Ensure that the timer is stopped before we allow PWM core to call 392 * pwm_enable. 393 */ 394 if (pm_runtime_active(&omap->dm_timer_pdev->dev)) 395 omap->pdata->stop(omap->dm_timer); 396 397 if (!of_property_read_u32(pdev->dev.of_node, "ti,prescaler", &v)) 398 omap->pdata->set_prescaler(omap->dm_timer, v); 399 400 /* setup dmtimer clock source */ 401 if (!of_property_read_u32(pdev->dev.of_node, "ti,clock-source", &v)) 402 omap->pdata->set_source(omap->dm_timer, v); 403 404 omap->chip.dev = &pdev->dev; 405 omap->chip.ops = &pwm_omap_dmtimer_ops; 406 omap->chip.npwm = 1; 407 408 mutex_init(&omap->mutex); 409 410 ret = pwmchip_add(&omap->chip); 411 if (ret < 0) { 412 dev_err(&pdev->dev, "failed to register PWM\n"); 413 goto err_pwmchip_add; 414 } 415 416 of_node_put(timer); 417 418 platform_set_drvdata(pdev, omap); 419 420 return 0; 421 422 err_pwmchip_add: 423 424 /* 425 * *omap is allocated using devm_kzalloc, 426 * so no free necessary here 427 */ 428 err_alloc_omap: 429 430 pdata->free(dm_timer); 431 err_request_timer: 432 433 err_timer_property: 434 err_platdata: 435 436 put_device(&timer_pdev->dev); 437 err_find_timer_pdev: 438 439 of_node_put(timer); 440 441 return ret; 442 } 443 444 static void pwm_omap_dmtimer_remove(struct platform_device *pdev) 445 { 446 struct pwm_omap_dmtimer_chip *omap = platform_get_drvdata(pdev); 447 448 pwmchip_remove(&omap->chip); 449 450 if (pm_runtime_active(&omap->dm_timer_pdev->dev)) 451 omap->pdata->stop(omap->dm_timer); 452 453 omap->pdata->free(omap->dm_timer); 454 455 put_device(&omap->dm_timer_pdev->dev); 456 457 mutex_destroy(&omap->mutex); 458 } 459 460 static const struct of_device_id pwm_omap_dmtimer_of_match[] = { 461 {.compatible = "ti,omap-dmtimer-pwm"}, 462 {} 463 }; 464 MODULE_DEVICE_TABLE(of, pwm_omap_dmtimer_of_match); 465 466 static struct platform_driver pwm_omap_dmtimer_driver = { 467 .driver = { 468 .name = "omap-dmtimer-pwm", 469 .of_match_table = of_match_ptr(pwm_omap_dmtimer_of_match), 470 }, 471 .probe = pwm_omap_dmtimer_probe, 472 .remove_new = pwm_omap_dmtimer_remove, 473 }; 474 module_platform_driver(pwm_omap_dmtimer_driver); 475 476 MODULE_AUTHOR("Grant Erickson <marathon96@gmail.com>"); 477 MODULE_AUTHOR("NeilBrown <neilb@suse.de>"); 478 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>"); 479 MODULE_LICENSE("GPL v2"); 480 MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers"); 481