1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for Atmel Pulse Width Modulation Controller 4 * 5 * Copyright (C) 2013 Atmel Corporation 6 * Bo Shen <voice.shen@atmel.com> 7 * 8 * Links to reference manuals for the supported PWM chips can be found in 9 * Documentation/arm/microchip.rst. 10 * 11 * Limitations: 12 * - Periods start with the inactive level. 13 * - Hardware has to be stopped in general to update settings. 14 * 15 * Software bugs/possible improvements: 16 * - When atmel_pwm_apply() is called with state->enabled=false a change in 17 * state->polarity isn't honored. 18 * - Instead of sleeping to wait for a completed period, the interrupt 19 * functionality could be used. 20 */ 21 22 #include <linux/clk.h> 23 #include <linux/delay.h> 24 #include <linux/err.h> 25 #include <linux/io.h> 26 #include <linux/module.h> 27 #include <linux/mutex.h> 28 #include <linux/of.h> 29 #include <linux/of_device.h> 30 #include <linux/platform_device.h> 31 #include <linux/pwm.h> 32 #include <linux/slab.h> 33 34 /* The following is global registers for PWM controller */ 35 #define PWM_ENA 0x04 36 #define PWM_DIS 0x08 37 #define PWM_SR 0x0C 38 #define PWM_ISR 0x1C 39 /* Bit field in SR */ 40 #define PWM_SR_ALL_CH_ON 0x0F 41 42 /* The following register is PWM channel related registers */ 43 #define PWM_CH_REG_OFFSET 0x200 44 #define PWM_CH_REG_SIZE 0x20 45 46 #define PWM_CMR 0x0 47 /* Bit field in CMR */ 48 #define PWM_CMR_CPOL (1 << 9) 49 #define PWM_CMR_UPD_CDTY (1 << 10) 50 #define PWM_CMR_CPRE_MSK 0xF 51 52 /* The following registers for PWM v1 */ 53 #define PWMV1_CDTY 0x04 54 #define PWMV1_CPRD 0x08 55 #define PWMV1_CUPD 0x10 56 57 /* The following registers for PWM v2 */ 58 #define PWMV2_CDTY 0x04 59 #define PWMV2_CDTYUPD 0x08 60 #define PWMV2_CPRD 0x0C 61 #define PWMV2_CPRDUPD 0x10 62 63 #define PWM_MAX_PRES 10 64 65 struct atmel_pwm_registers { 66 u8 period; 67 u8 period_upd; 68 u8 duty; 69 u8 duty_upd; 70 }; 71 72 struct atmel_pwm_config { 73 u32 period_bits; 74 }; 75 76 struct atmel_pwm_data { 77 struct atmel_pwm_registers regs; 78 struct atmel_pwm_config cfg; 79 }; 80 81 struct atmel_pwm_chip { 82 struct pwm_chip chip; 83 struct clk *clk; 84 void __iomem *base; 85 const struct atmel_pwm_data *data; 86 87 unsigned int updated_pwms; 88 /* ISR is cleared when read, ensure only one thread does that */ 89 struct mutex isr_lock; 90 }; 91 92 static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip) 93 { 94 return container_of(chip, struct atmel_pwm_chip, chip); 95 } 96 97 static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip, 98 unsigned long offset) 99 { 100 return readl_relaxed(chip->base + offset); 101 } 102 103 static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip, 104 unsigned long offset, unsigned long val) 105 { 106 writel_relaxed(val, chip->base + offset); 107 } 108 109 static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip, 110 unsigned int ch, unsigned long offset) 111 { 112 unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE; 113 114 return atmel_pwm_readl(chip, base + offset); 115 } 116 117 static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip, 118 unsigned int ch, unsigned long offset, 119 unsigned long val) 120 { 121 unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE; 122 123 atmel_pwm_writel(chip, base + offset, val); 124 } 125 126 static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip, 127 unsigned long clkrate, 128 const struct pwm_state *state, 129 unsigned long *cprd, u32 *pres) 130 { 131 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 132 unsigned long long cycles = state->period; 133 int shift; 134 135 /* Calculate the period cycles and prescale value */ 136 cycles *= clkrate; 137 do_div(cycles, NSEC_PER_SEC); 138 139 /* 140 * The register for the period length is cfg.period_bits bits wide. 141 * So for each bit the number of clock cycles is wider divide the input 142 * clock frequency by two using pres and shift cprd accordingly. 143 */ 144 shift = fls(cycles) - atmel_pwm->data->cfg.period_bits; 145 146 if (shift > PWM_MAX_PRES) { 147 dev_err(chip->dev, "pres exceeds the maximum value\n"); 148 return -EINVAL; 149 } else if (shift > 0) { 150 *pres = shift; 151 cycles >>= *pres; 152 } else { 153 *pres = 0; 154 } 155 156 *cprd = cycles; 157 158 return 0; 159 } 160 161 static void atmel_pwm_calculate_cdty(const struct pwm_state *state, 162 unsigned long clkrate, unsigned long cprd, 163 u32 pres, unsigned long *cdty) 164 { 165 unsigned long long cycles = state->duty_cycle; 166 167 cycles *= clkrate; 168 do_div(cycles, NSEC_PER_SEC); 169 cycles >>= pres; 170 *cdty = cprd - cycles; 171 } 172 173 static void atmel_pwm_update_cdty(struct pwm_chip *chip, struct pwm_device *pwm, 174 unsigned long cdty) 175 { 176 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 177 u32 val; 178 179 if (atmel_pwm->data->regs.duty_upd == 180 atmel_pwm->data->regs.period_upd) { 181 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 182 val &= ~PWM_CMR_UPD_CDTY; 183 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val); 184 } 185 186 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, 187 atmel_pwm->data->regs.duty_upd, cdty); 188 } 189 190 static void atmel_pwm_set_cprd_cdty(struct pwm_chip *chip, 191 struct pwm_device *pwm, 192 unsigned long cprd, unsigned long cdty) 193 { 194 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 195 196 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, 197 atmel_pwm->data->regs.duty, cdty); 198 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, 199 atmel_pwm->data->regs.period, cprd); 200 } 201 202 static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm, 203 bool disable_clk) 204 { 205 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 206 unsigned long timeout = jiffies + 2 * HZ; 207 208 /* 209 * Wait for at least a complete period to have passed before disabling a 210 * channel to be sure that CDTY has been updated 211 */ 212 mutex_lock(&atmel_pwm->isr_lock); 213 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR); 214 215 while (!(atmel_pwm->updated_pwms & (1 << pwm->hwpwm)) && 216 time_before(jiffies, timeout)) { 217 usleep_range(10, 100); 218 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR); 219 } 220 221 mutex_unlock(&atmel_pwm->isr_lock); 222 atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm); 223 224 /* 225 * Wait for the PWM channel disable operation to be effective before 226 * stopping the clock. 227 */ 228 timeout = jiffies + 2 * HZ; 229 230 while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) && 231 time_before(jiffies, timeout)) 232 usleep_range(10, 100); 233 234 if (disable_clk) 235 clk_disable(atmel_pwm->clk); 236 } 237 238 static int atmel_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 239 const struct pwm_state *state) 240 { 241 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 242 struct pwm_state cstate; 243 unsigned long cprd, cdty; 244 u32 pres, val; 245 int ret; 246 247 pwm_get_state(pwm, &cstate); 248 249 if (state->enabled) { 250 unsigned long clkrate = clk_get_rate(atmel_pwm->clk); 251 252 if (cstate.enabled && 253 cstate.polarity == state->polarity && 254 cstate.period == state->period) { 255 u32 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 256 257 cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, 258 atmel_pwm->data->regs.period); 259 pres = cmr & PWM_CMR_CPRE_MSK; 260 261 atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty); 262 atmel_pwm_update_cdty(chip, pwm, cdty); 263 return 0; 264 } 265 266 ret = atmel_pwm_calculate_cprd_and_pres(chip, clkrate, state, &cprd, 267 &pres); 268 if (ret) { 269 dev_err(chip->dev, 270 "failed to calculate cprd and prescaler\n"); 271 return ret; 272 } 273 274 atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty); 275 276 if (cstate.enabled) { 277 atmel_pwm_disable(chip, pwm, false); 278 } else { 279 ret = clk_enable(atmel_pwm->clk); 280 if (ret) { 281 dev_err(chip->dev, "failed to enable clock\n"); 282 return ret; 283 } 284 } 285 286 /* It is necessary to preserve CPOL, inside CMR */ 287 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 288 val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK); 289 if (state->polarity == PWM_POLARITY_NORMAL) 290 val &= ~PWM_CMR_CPOL; 291 else 292 val |= PWM_CMR_CPOL; 293 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val); 294 atmel_pwm_set_cprd_cdty(chip, pwm, cprd, cdty); 295 mutex_lock(&atmel_pwm->isr_lock); 296 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR); 297 atmel_pwm->updated_pwms &= ~(1 << pwm->hwpwm); 298 mutex_unlock(&atmel_pwm->isr_lock); 299 atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm); 300 } else if (cstate.enabled) { 301 atmel_pwm_disable(chip, pwm, true); 302 } 303 304 return 0; 305 } 306 307 static void atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 308 struct pwm_state *state) 309 { 310 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 311 u32 sr, cmr; 312 313 sr = atmel_pwm_readl(atmel_pwm, PWM_SR); 314 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 315 316 if (sr & (1 << pwm->hwpwm)) { 317 unsigned long rate = clk_get_rate(atmel_pwm->clk); 318 u32 cdty, cprd, pres; 319 u64 tmp; 320 321 pres = cmr & PWM_CMR_CPRE_MSK; 322 323 cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, 324 atmel_pwm->data->regs.period); 325 tmp = (u64)cprd * NSEC_PER_SEC; 326 tmp <<= pres; 327 state->period = DIV64_U64_ROUND_UP(tmp, rate); 328 329 cdty = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, 330 atmel_pwm->data->regs.duty); 331 tmp = (u64)(cprd - cdty) * NSEC_PER_SEC; 332 tmp <<= pres; 333 state->duty_cycle = DIV64_U64_ROUND_UP(tmp, rate); 334 335 state->enabled = true; 336 } else { 337 state->enabled = false; 338 } 339 340 if (cmr & PWM_CMR_CPOL) 341 state->polarity = PWM_POLARITY_INVERSED; 342 else 343 state->polarity = PWM_POLARITY_NORMAL; 344 } 345 346 static const struct pwm_ops atmel_pwm_ops = { 347 .apply = atmel_pwm_apply, 348 .get_state = atmel_pwm_get_state, 349 .owner = THIS_MODULE, 350 }; 351 352 static const struct atmel_pwm_data atmel_sam9rl_pwm_data = { 353 .regs = { 354 .period = PWMV1_CPRD, 355 .period_upd = PWMV1_CUPD, 356 .duty = PWMV1_CDTY, 357 .duty_upd = PWMV1_CUPD, 358 }, 359 .cfg = { 360 /* 16 bits to keep period and duty. */ 361 .period_bits = 16, 362 }, 363 }; 364 365 static const struct atmel_pwm_data atmel_sama5_pwm_data = { 366 .regs = { 367 .period = PWMV2_CPRD, 368 .period_upd = PWMV2_CPRDUPD, 369 .duty = PWMV2_CDTY, 370 .duty_upd = PWMV2_CDTYUPD, 371 }, 372 .cfg = { 373 /* 16 bits to keep period and duty. */ 374 .period_bits = 16, 375 }, 376 }; 377 378 static const struct atmel_pwm_data mchp_sam9x60_pwm_data = { 379 .regs = { 380 .period = PWMV1_CPRD, 381 .period_upd = PWMV1_CUPD, 382 .duty = PWMV1_CDTY, 383 .duty_upd = PWMV1_CUPD, 384 }, 385 .cfg = { 386 /* 32 bits to keep period and duty. */ 387 .period_bits = 32, 388 }, 389 }; 390 391 static const struct of_device_id atmel_pwm_dt_ids[] = { 392 { 393 .compatible = "atmel,at91sam9rl-pwm", 394 .data = &atmel_sam9rl_pwm_data, 395 }, { 396 .compatible = "atmel,sama5d3-pwm", 397 .data = &atmel_sama5_pwm_data, 398 }, { 399 .compatible = "atmel,sama5d2-pwm", 400 .data = &atmel_sama5_pwm_data, 401 }, { 402 .compatible = "microchip,sam9x60-pwm", 403 .data = &mchp_sam9x60_pwm_data, 404 }, { 405 /* sentinel */ 406 }, 407 }; 408 MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids); 409 410 static int atmel_pwm_probe(struct platform_device *pdev) 411 { 412 struct atmel_pwm_chip *atmel_pwm; 413 int ret; 414 415 atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL); 416 if (!atmel_pwm) 417 return -ENOMEM; 418 419 mutex_init(&atmel_pwm->isr_lock); 420 atmel_pwm->data = of_device_get_match_data(&pdev->dev); 421 atmel_pwm->updated_pwms = 0; 422 423 atmel_pwm->base = devm_platform_ioremap_resource(pdev, 0); 424 if (IS_ERR(atmel_pwm->base)) 425 return PTR_ERR(atmel_pwm->base); 426 427 atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL); 428 if (IS_ERR(atmel_pwm->clk)) 429 return PTR_ERR(atmel_pwm->clk); 430 431 ret = clk_prepare(atmel_pwm->clk); 432 if (ret) { 433 dev_err(&pdev->dev, "failed to prepare PWM clock\n"); 434 return ret; 435 } 436 437 atmel_pwm->chip.dev = &pdev->dev; 438 atmel_pwm->chip.ops = &atmel_pwm_ops; 439 atmel_pwm->chip.npwm = 4; 440 441 ret = pwmchip_add(&atmel_pwm->chip); 442 if (ret < 0) { 443 dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret); 444 goto unprepare_clk; 445 } 446 447 platform_set_drvdata(pdev, atmel_pwm); 448 449 return ret; 450 451 unprepare_clk: 452 clk_unprepare(atmel_pwm->clk); 453 return ret; 454 } 455 456 static int atmel_pwm_remove(struct platform_device *pdev) 457 { 458 struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev); 459 460 pwmchip_remove(&atmel_pwm->chip); 461 462 clk_unprepare(atmel_pwm->clk); 463 mutex_destroy(&atmel_pwm->isr_lock); 464 465 return 0; 466 } 467 468 static struct platform_driver atmel_pwm_driver = { 469 .driver = { 470 .name = "atmel-pwm", 471 .of_match_table = of_match_ptr(atmel_pwm_dt_ids), 472 }, 473 .probe = atmel_pwm_probe, 474 .remove = atmel_pwm_remove, 475 }; 476 module_platform_driver(atmel_pwm_driver); 477 478 MODULE_ALIAS("platform:atmel-pwm"); 479 MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>"); 480 MODULE_DESCRIPTION("Atmel PWM driver"); 481 MODULE_LICENSE("GPL v2"); 482