1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for Allwinner sun4i Pulse Width Modulation Controller 4 * 5 * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com> 6 * 7 * Limitations: 8 * - When outputing the source clock directly, the PWM logic will be bypassed 9 * and the currently running period is not guaranteed to be completed 10 */ 11 12 #include <linux/bitops.h> 13 #include <linux/clk.h> 14 #include <linux/delay.h> 15 #include <linux/err.h> 16 #include <linux/io.h> 17 #include <linux/jiffies.h> 18 #include <linux/module.h> 19 #include <linux/of.h> 20 #include <linux/of_device.h> 21 #include <linux/platform_device.h> 22 #include <linux/pwm.h> 23 #include <linux/reset.h> 24 #include <linux/slab.h> 25 #include <linux/spinlock.h> 26 #include <linux/time.h> 27 28 #define PWM_CTRL_REG 0x0 29 30 #define PWM_CH_PRD_BASE 0x4 31 #define PWM_CH_PRD_OFFSET 0x4 32 #define PWM_CH_PRD(ch) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch)) 33 34 #define PWMCH_OFFSET 15 35 #define PWM_PRESCAL_MASK GENMASK(3, 0) 36 #define PWM_PRESCAL_OFF 0 37 #define PWM_EN BIT(4) 38 #define PWM_ACT_STATE BIT(5) 39 #define PWM_CLK_GATING BIT(6) 40 #define PWM_MODE BIT(7) 41 #define PWM_PULSE BIT(8) 42 #define PWM_BYPASS BIT(9) 43 44 #define PWM_RDY_BASE 28 45 #define PWM_RDY_OFFSET 1 46 #define PWM_RDY(ch) BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch)) 47 48 #define PWM_PRD(prd) (((prd) - 1) << 16) 49 #define PWM_PRD_MASK GENMASK(15, 0) 50 51 #define PWM_DTY_MASK GENMASK(15, 0) 52 53 #define PWM_REG_PRD(reg) ((((reg) >> 16) & PWM_PRD_MASK) + 1) 54 #define PWM_REG_DTY(reg) ((reg) & PWM_DTY_MASK) 55 #define PWM_REG_PRESCAL(reg, chan) (((reg) >> ((chan) * PWMCH_OFFSET)) & PWM_PRESCAL_MASK) 56 57 #define BIT_CH(bit, chan) ((bit) << ((chan) * PWMCH_OFFSET)) 58 59 static const u32 prescaler_table[] = { 60 120, 61 180, 62 240, 63 360, 64 480, 65 0, 66 0, 67 0, 68 12000, 69 24000, 70 36000, 71 48000, 72 72000, 73 0, 74 0, 75 0, /* Actually 1 but tested separately */ 76 }; 77 78 struct sun4i_pwm_data { 79 bool has_prescaler_bypass; 80 bool has_direct_mod_clk_output; 81 unsigned int npwm; 82 }; 83 84 struct sun4i_pwm_chip { 85 struct pwm_chip chip; 86 struct clk *bus_clk; 87 struct clk *clk; 88 struct reset_control *rst; 89 void __iomem *base; 90 spinlock_t ctrl_lock; 91 const struct sun4i_pwm_data *data; 92 unsigned long next_period[2]; 93 bool needs_delay[2]; 94 }; 95 96 static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip) 97 { 98 return container_of(chip, struct sun4i_pwm_chip, chip); 99 } 100 101 static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip, 102 unsigned long offset) 103 { 104 return readl(chip->base + offset); 105 } 106 107 static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip, 108 u32 val, unsigned long offset) 109 { 110 writel(val, chip->base + offset); 111 } 112 113 static void sun4i_pwm_get_state(struct pwm_chip *chip, 114 struct pwm_device *pwm, 115 struct pwm_state *state) 116 { 117 struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); 118 u64 clk_rate, tmp; 119 u32 val; 120 unsigned int prescaler; 121 122 clk_rate = clk_get_rate(sun4i_pwm->clk); 123 124 val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); 125 126 /* 127 * PWM chapter in H6 manual has a diagram which explains that if bypass 128 * bit is set, no other setting has any meaning. Even more, experiment 129 * proved that also enable bit is ignored in this case. 130 */ 131 if ((val & BIT_CH(PWM_BYPASS, pwm->hwpwm)) && 132 sun4i_pwm->data->has_direct_mod_clk_output) { 133 state->period = DIV_ROUND_UP_ULL(NSEC_PER_SEC, clk_rate); 134 state->duty_cycle = DIV_ROUND_UP_ULL(state->period, 2); 135 state->polarity = PWM_POLARITY_NORMAL; 136 state->enabled = true; 137 return; 138 } 139 140 if ((PWM_REG_PRESCAL(val, pwm->hwpwm) == PWM_PRESCAL_MASK) && 141 sun4i_pwm->data->has_prescaler_bypass) 142 prescaler = 1; 143 else 144 prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)]; 145 146 if (prescaler == 0) 147 return; 148 149 if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm)) 150 state->polarity = PWM_POLARITY_NORMAL; 151 else 152 state->polarity = PWM_POLARITY_INVERSED; 153 154 if ((val & BIT_CH(PWM_CLK_GATING | PWM_EN, pwm->hwpwm)) == 155 BIT_CH(PWM_CLK_GATING | PWM_EN, pwm->hwpwm)) 156 state->enabled = true; 157 else 158 state->enabled = false; 159 160 val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm)); 161 162 tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_DTY(val); 163 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); 164 165 tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_PRD(val); 166 state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate); 167 } 168 169 static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm, 170 const struct pwm_state *state, 171 u32 *dty, u32 *prd, unsigned int *prsclr, 172 bool *bypass) 173 { 174 u64 clk_rate, div = 0; 175 unsigned int prescaler = 0; 176 177 clk_rate = clk_get_rate(sun4i_pwm->clk); 178 179 *bypass = sun4i_pwm->data->has_direct_mod_clk_output && 180 state->enabled && 181 (state->period * clk_rate >= NSEC_PER_SEC) && 182 (state->period * clk_rate < 2 * NSEC_PER_SEC) && 183 (state->duty_cycle * clk_rate * 2 >= NSEC_PER_SEC); 184 185 /* Skip calculation of other parameters if we bypass them */ 186 if (*bypass) 187 return 0; 188 189 if (sun4i_pwm->data->has_prescaler_bypass) { 190 /* First, test without any prescaler when available */ 191 prescaler = PWM_PRESCAL_MASK; 192 /* 193 * When not using any prescaler, the clock period in nanoseconds 194 * is not an integer so round it half up instead of 195 * truncating to get less surprising values. 196 */ 197 div = clk_rate * state->period + NSEC_PER_SEC / 2; 198 do_div(div, NSEC_PER_SEC); 199 if (div - 1 > PWM_PRD_MASK) 200 prescaler = 0; 201 } 202 203 if (prescaler == 0) { 204 /* Go up from the first divider */ 205 for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) { 206 unsigned int pval = prescaler_table[prescaler]; 207 208 if (!pval) 209 continue; 210 211 div = clk_rate; 212 do_div(div, pval); 213 div = div * state->period; 214 do_div(div, NSEC_PER_SEC); 215 if (div - 1 <= PWM_PRD_MASK) 216 break; 217 } 218 219 if (div - 1 > PWM_PRD_MASK) 220 return -EINVAL; 221 } 222 223 *prd = div; 224 div *= state->duty_cycle; 225 do_div(div, state->period); 226 *dty = div; 227 *prsclr = prescaler; 228 229 return 0; 230 } 231 232 static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 233 const struct pwm_state *state) 234 { 235 struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip); 236 struct pwm_state cstate; 237 u32 ctrl, duty = 0, period = 0, val; 238 int ret; 239 unsigned int delay_us, prescaler = 0; 240 unsigned long now; 241 bool bypass; 242 243 pwm_get_state(pwm, &cstate); 244 245 if (!cstate.enabled) { 246 ret = clk_prepare_enable(sun4i_pwm->clk); 247 if (ret) { 248 dev_err(chip->dev, "failed to enable PWM clock\n"); 249 return ret; 250 } 251 } 252 253 ret = sun4i_pwm_calculate(sun4i_pwm, state, &duty, &period, &prescaler, 254 &bypass); 255 if (ret) { 256 dev_err(chip->dev, "period exceeds the maximum value\n"); 257 if (!cstate.enabled) 258 clk_disable_unprepare(sun4i_pwm->clk); 259 return ret; 260 } 261 262 spin_lock(&sun4i_pwm->ctrl_lock); 263 ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); 264 265 if (sun4i_pwm->data->has_direct_mod_clk_output) { 266 if (bypass) { 267 ctrl |= BIT_CH(PWM_BYPASS, pwm->hwpwm); 268 /* We can skip other parameter */ 269 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); 270 spin_unlock(&sun4i_pwm->ctrl_lock); 271 return 0; 272 } 273 274 ctrl &= ~BIT_CH(PWM_BYPASS, pwm->hwpwm); 275 } 276 277 if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) { 278 /* Prescaler changed, the clock has to be gated */ 279 ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); 280 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); 281 282 ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm); 283 ctrl |= BIT_CH(prescaler, pwm->hwpwm); 284 } 285 286 val = (duty & PWM_DTY_MASK) | PWM_PRD(period); 287 sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm)); 288 sun4i_pwm->next_period[pwm->hwpwm] = jiffies + 289 usecs_to_jiffies(cstate.period / 1000 + 1); 290 sun4i_pwm->needs_delay[pwm->hwpwm] = true; 291 292 if (state->polarity != PWM_POLARITY_NORMAL) 293 ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm); 294 else 295 ctrl |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm); 296 297 ctrl |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm); 298 299 if (state->enabled) { 300 ctrl |= BIT_CH(PWM_EN, pwm->hwpwm); 301 } else if (!sun4i_pwm->needs_delay[pwm->hwpwm]) { 302 ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm); 303 ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); 304 } 305 306 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); 307 308 spin_unlock(&sun4i_pwm->ctrl_lock); 309 310 if (state->enabled) 311 return 0; 312 313 if (!sun4i_pwm->needs_delay[pwm->hwpwm]) { 314 clk_disable_unprepare(sun4i_pwm->clk); 315 return 0; 316 } 317 318 /* We need a full period to elapse before disabling the channel. */ 319 now = jiffies; 320 if (sun4i_pwm->needs_delay[pwm->hwpwm] && 321 time_before(now, sun4i_pwm->next_period[pwm->hwpwm])) { 322 delay_us = jiffies_to_usecs(sun4i_pwm->next_period[pwm->hwpwm] - 323 now); 324 if ((delay_us / 500) > MAX_UDELAY_MS) 325 msleep(delay_us / 1000 + 1); 326 else 327 usleep_range(delay_us, delay_us * 2); 328 } 329 sun4i_pwm->needs_delay[pwm->hwpwm] = false; 330 331 spin_lock(&sun4i_pwm->ctrl_lock); 332 ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG); 333 ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm); 334 ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm); 335 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG); 336 spin_unlock(&sun4i_pwm->ctrl_lock); 337 338 clk_disable_unprepare(sun4i_pwm->clk); 339 340 return 0; 341 } 342 343 static const struct pwm_ops sun4i_pwm_ops = { 344 .apply = sun4i_pwm_apply, 345 .get_state = sun4i_pwm_get_state, 346 .owner = THIS_MODULE, 347 }; 348 349 static const struct sun4i_pwm_data sun4i_pwm_dual_nobypass = { 350 .has_prescaler_bypass = false, 351 .npwm = 2, 352 }; 353 354 static const struct sun4i_pwm_data sun4i_pwm_dual_bypass = { 355 .has_prescaler_bypass = true, 356 .npwm = 2, 357 }; 358 359 static const struct sun4i_pwm_data sun4i_pwm_single_bypass = { 360 .has_prescaler_bypass = true, 361 .npwm = 1, 362 }; 363 364 static const struct sun4i_pwm_data sun50i_h6_pwm_data = { 365 .has_prescaler_bypass = true, 366 .has_direct_mod_clk_output = true, 367 .npwm = 2, 368 }; 369 370 static const struct of_device_id sun4i_pwm_dt_ids[] = { 371 { 372 .compatible = "allwinner,sun4i-a10-pwm", 373 .data = &sun4i_pwm_dual_nobypass, 374 }, { 375 .compatible = "allwinner,sun5i-a10s-pwm", 376 .data = &sun4i_pwm_dual_bypass, 377 }, { 378 .compatible = "allwinner,sun5i-a13-pwm", 379 .data = &sun4i_pwm_single_bypass, 380 }, { 381 .compatible = "allwinner,sun7i-a20-pwm", 382 .data = &sun4i_pwm_dual_bypass, 383 }, { 384 .compatible = "allwinner,sun8i-h3-pwm", 385 .data = &sun4i_pwm_single_bypass, 386 }, { 387 .compatible = "allwinner,sun50i-h6-pwm", 388 .data = &sun50i_h6_pwm_data, 389 }, { 390 /* sentinel */ 391 }, 392 }; 393 MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids); 394 395 static int sun4i_pwm_probe(struct platform_device *pdev) 396 { 397 struct sun4i_pwm_chip *pwm; 398 struct resource *res; 399 int ret; 400 401 pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); 402 if (!pwm) 403 return -ENOMEM; 404 405 pwm->data = of_device_get_match_data(&pdev->dev); 406 if (!pwm->data) 407 return -ENODEV; 408 409 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 410 pwm->base = devm_ioremap_resource(&pdev->dev, res); 411 if (IS_ERR(pwm->base)) 412 return PTR_ERR(pwm->base); 413 414 /* 415 * All hardware variants need a source clock that is divided and 416 * then feeds the counter that defines the output wave form. In the 417 * device tree this clock is either unnamed or called "mod". 418 * Some variants (e.g. H6) need another clock to access the 419 * hardware registers; this is called "bus". 420 * So we request "mod" first (and ignore the corner case that a 421 * parent provides a "mod" clock while the right one would be the 422 * unnamed one of the PWM device) and if this is not found we fall 423 * back to the first clock of the PWM. 424 */ 425 pwm->clk = devm_clk_get_optional(&pdev->dev, "mod"); 426 if (IS_ERR(pwm->clk)) { 427 if (PTR_ERR(pwm->clk) != -EPROBE_DEFER) 428 dev_err(&pdev->dev, "get mod clock failed %pe\n", 429 pwm->clk); 430 return PTR_ERR(pwm->clk); 431 } 432 433 if (!pwm->clk) { 434 pwm->clk = devm_clk_get(&pdev->dev, NULL); 435 if (IS_ERR(pwm->clk)) { 436 if (PTR_ERR(pwm->clk) != -EPROBE_DEFER) 437 dev_err(&pdev->dev, "get unnamed clock failed %pe\n", 438 pwm->clk); 439 return PTR_ERR(pwm->clk); 440 } 441 } 442 443 pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus"); 444 if (IS_ERR(pwm->bus_clk)) { 445 if (PTR_ERR(pwm->bus_clk) != -EPROBE_DEFER) 446 dev_err(&pdev->dev, "get bus clock failed %pe\n", 447 pwm->bus_clk); 448 return PTR_ERR(pwm->bus_clk); 449 } 450 451 pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL); 452 if (IS_ERR(pwm->rst)) { 453 if (PTR_ERR(pwm->rst) != -EPROBE_DEFER) 454 dev_err(&pdev->dev, "get reset failed %pe\n", 455 pwm->rst); 456 return PTR_ERR(pwm->rst); 457 } 458 459 /* Deassert reset */ 460 ret = reset_control_deassert(pwm->rst); 461 if (ret) { 462 dev_err(&pdev->dev, "cannot deassert reset control: %pe\n", 463 ERR_PTR(ret)); 464 return ret; 465 } 466 467 /* 468 * We're keeping the bus clock on for the sake of simplicity. 469 * Actually it only needs to be on for hardware register accesses. 470 */ 471 ret = clk_prepare_enable(pwm->bus_clk); 472 if (ret) { 473 dev_err(&pdev->dev, "cannot prepare and enable bus_clk %pe\n", 474 ERR_PTR(ret)); 475 goto err_bus; 476 } 477 478 pwm->chip.dev = &pdev->dev; 479 pwm->chip.ops = &sun4i_pwm_ops; 480 pwm->chip.base = -1; 481 pwm->chip.npwm = pwm->data->npwm; 482 pwm->chip.of_xlate = of_pwm_xlate_with_flags; 483 pwm->chip.of_pwm_n_cells = 3; 484 485 spin_lock_init(&pwm->ctrl_lock); 486 487 ret = pwmchip_add(&pwm->chip); 488 if (ret < 0) { 489 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); 490 goto err_pwm_add; 491 } 492 493 platform_set_drvdata(pdev, pwm); 494 495 return 0; 496 497 err_pwm_add: 498 clk_disable_unprepare(pwm->bus_clk); 499 err_bus: 500 reset_control_assert(pwm->rst); 501 502 return ret; 503 } 504 505 static int sun4i_pwm_remove(struct platform_device *pdev) 506 { 507 struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev); 508 int ret; 509 510 ret = pwmchip_remove(&pwm->chip); 511 if (ret) 512 return ret; 513 514 clk_disable_unprepare(pwm->bus_clk); 515 reset_control_assert(pwm->rst); 516 517 return 0; 518 } 519 520 static struct platform_driver sun4i_pwm_driver = { 521 .driver = { 522 .name = "sun4i-pwm", 523 .of_match_table = sun4i_pwm_dt_ids, 524 }, 525 .probe = sun4i_pwm_probe, 526 .remove = sun4i_pwm_remove, 527 }; 528 module_platform_driver(sun4i_pwm_driver); 529 530 MODULE_ALIAS("platform:sun4i-pwm"); 531 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>"); 532 MODULE_DESCRIPTION("Allwinner sun4i PWM driver"); 533 MODULE_LICENSE("GPL v2"); 534