1 /* 2 * Driver for Atmel Pulse Width Modulation Controller 3 * 4 * Copyright (C) 2013 Atmel Corporation 5 * Bo Shen <voice.shen@atmel.com> 6 * 7 * Licensed under GPLv2. 8 */ 9 10 #include <linux/clk.h> 11 #include <linux/delay.h> 12 #include <linux/err.h> 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/mutex.h> 16 #include <linux/of.h> 17 #include <linux/of_device.h> 18 #include <linux/platform_device.h> 19 #include <linux/pwm.h> 20 #include <linux/slab.h> 21 22 /* The following is global registers for PWM controller */ 23 #define PWM_ENA 0x04 24 #define PWM_DIS 0x08 25 #define PWM_SR 0x0C 26 #define PWM_ISR 0x1C 27 /* Bit field in SR */ 28 #define PWM_SR_ALL_CH_ON 0x0F 29 30 /* The following register is PWM channel related registers */ 31 #define PWM_CH_REG_OFFSET 0x200 32 #define PWM_CH_REG_SIZE 0x20 33 34 #define PWM_CMR 0x0 35 /* Bit field in CMR */ 36 #define PWM_CMR_CPOL (1 << 9) 37 #define PWM_CMR_UPD_CDTY (1 << 10) 38 #define PWM_CMR_CPRE_MSK 0xF 39 40 /* The following registers for PWM v1 */ 41 #define PWMV1_CDTY 0x04 42 #define PWMV1_CPRD 0x08 43 #define PWMV1_CUPD 0x10 44 45 /* The following registers for PWM v2 */ 46 #define PWMV2_CDTY 0x04 47 #define PWMV2_CDTYUPD 0x08 48 #define PWMV2_CPRD 0x0C 49 #define PWMV2_CPRDUPD 0x10 50 51 /* 52 * Max value for duty and period 53 * 54 * Although the duty and period register is 32 bit, 55 * however only the LSB 16 bits are significant. 56 */ 57 #define PWM_MAX_DTY 0xFFFF 58 #define PWM_MAX_PRD 0xFFFF 59 #define PRD_MAX_PRES 10 60 61 struct atmel_pwm_chip { 62 struct pwm_chip chip; 63 struct clk *clk; 64 void __iomem *base; 65 66 unsigned int updated_pwms; 67 /* ISR is cleared when read, ensure only one thread does that */ 68 struct mutex isr_lock; 69 70 void (*config)(struct pwm_chip *chip, struct pwm_device *pwm, 71 unsigned long dty, unsigned long prd); 72 }; 73 74 static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip) 75 { 76 return container_of(chip, struct atmel_pwm_chip, chip); 77 } 78 79 static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip, 80 unsigned long offset) 81 { 82 return readl_relaxed(chip->base + offset); 83 } 84 85 static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip, 86 unsigned long offset, unsigned long val) 87 { 88 writel_relaxed(val, chip->base + offset); 89 } 90 91 static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip, 92 unsigned int ch, unsigned long offset) 93 { 94 unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE; 95 96 return readl_relaxed(chip->base + base + offset); 97 } 98 99 static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip, 100 unsigned int ch, unsigned long offset, 101 unsigned long val) 102 { 103 unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE; 104 105 writel_relaxed(val, chip->base + base + offset); 106 } 107 108 static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 109 int duty_ns, int period_ns) 110 { 111 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 112 unsigned long prd, dty; 113 unsigned long long div; 114 unsigned int pres = 0; 115 u32 val; 116 int ret; 117 118 if (pwm_is_enabled(pwm) && (period_ns != pwm_get_period(pwm))) { 119 dev_err(chip->dev, "cannot change PWM period while enabled\n"); 120 return -EBUSY; 121 } 122 123 /* Calculate the period cycles and prescale value */ 124 div = (unsigned long long)clk_get_rate(atmel_pwm->clk) * period_ns; 125 do_div(div, NSEC_PER_SEC); 126 127 while (div > PWM_MAX_PRD) { 128 div >>= 1; 129 pres++; 130 } 131 132 if (pres > PRD_MAX_PRES) { 133 dev_err(chip->dev, "pres exceeds the maximum value\n"); 134 return -EINVAL; 135 } 136 137 /* Calculate the duty cycles */ 138 prd = div; 139 div *= duty_ns; 140 do_div(div, period_ns); 141 dty = prd - div; 142 143 ret = clk_enable(atmel_pwm->clk); 144 if (ret) { 145 dev_err(chip->dev, "failed to enable PWM clock\n"); 146 return ret; 147 } 148 149 /* It is necessary to preserve CPOL, inside CMR */ 150 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 151 val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK); 152 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val); 153 atmel_pwm->config(chip, pwm, dty, prd); 154 mutex_lock(&atmel_pwm->isr_lock); 155 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR); 156 atmel_pwm->updated_pwms &= ~(1 << pwm->hwpwm); 157 mutex_unlock(&atmel_pwm->isr_lock); 158 159 clk_disable(atmel_pwm->clk); 160 return ret; 161 } 162 163 static void atmel_pwm_config_v1(struct pwm_chip *chip, struct pwm_device *pwm, 164 unsigned long dty, unsigned long prd) 165 { 166 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 167 unsigned int val; 168 169 170 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CUPD, dty); 171 172 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 173 val &= ~PWM_CMR_UPD_CDTY; 174 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val); 175 176 /* 177 * If the PWM channel is enabled, only update CDTY by using the update 178 * register, it needs to set bit 10 of CMR to 0 179 */ 180 if (pwm_is_enabled(pwm)) 181 return; 182 /* 183 * If the PWM channel is disabled, write value to duty and period 184 * registers directly. 185 */ 186 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CDTY, dty); 187 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CPRD, prd); 188 } 189 190 static void atmel_pwm_config_v2(struct pwm_chip *chip, struct pwm_device *pwm, 191 unsigned long dty, unsigned long prd) 192 { 193 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 194 195 if (pwm_is_enabled(pwm)) { 196 /* 197 * If the PWM channel is enabled, using the duty update register 198 * to update the value. 199 */ 200 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTYUPD, dty); 201 } else { 202 /* 203 * If the PWM channel is disabled, write value to duty and 204 * period registers directly. 205 */ 206 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTY, dty); 207 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CPRD, prd); 208 } 209 } 210 211 static int atmel_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, 212 enum pwm_polarity polarity) 213 { 214 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 215 u32 val; 216 int ret; 217 218 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR); 219 220 if (polarity == PWM_POLARITY_NORMAL) 221 val &= ~PWM_CMR_CPOL; 222 else 223 val |= PWM_CMR_CPOL; 224 225 ret = clk_enable(atmel_pwm->clk); 226 if (ret) { 227 dev_err(chip->dev, "failed to enable PWM clock\n"); 228 return ret; 229 } 230 231 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val); 232 233 clk_disable(atmel_pwm->clk); 234 235 return 0; 236 } 237 238 static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 239 { 240 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 241 int ret; 242 243 ret = clk_enable(atmel_pwm->clk); 244 if (ret) { 245 dev_err(chip->dev, "failed to enable PWM clock\n"); 246 return ret; 247 } 248 249 atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm); 250 251 return 0; 252 } 253 254 static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 255 { 256 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); 257 unsigned long timeout = jiffies + 2 * HZ; 258 259 /* 260 * Wait for at least a complete period to have passed before disabling a 261 * channel to be sure that CDTY has been updated 262 */ 263 mutex_lock(&atmel_pwm->isr_lock); 264 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR); 265 266 while (!(atmel_pwm->updated_pwms & (1 << pwm->hwpwm)) && 267 time_before(jiffies, timeout)) { 268 usleep_range(10, 100); 269 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR); 270 } 271 272 mutex_unlock(&atmel_pwm->isr_lock); 273 atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm); 274 275 /* 276 * Wait for the PWM channel disable operation to be effective before 277 * stopping the clock. 278 */ 279 timeout = jiffies + 2 * HZ; 280 281 while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) && 282 time_before(jiffies, timeout)) 283 usleep_range(10, 100); 284 285 clk_disable(atmel_pwm->clk); 286 } 287 288 static const struct pwm_ops atmel_pwm_ops = { 289 .config = atmel_pwm_config, 290 .set_polarity = atmel_pwm_set_polarity, 291 .enable = atmel_pwm_enable, 292 .disable = atmel_pwm_disable, 293 .owner = THIS_MODULE, 294 }; 295 296 struct atmel_pwm_data { 297 void (*config)(struct pwm_chip *chip, struct pwm_device *pwm, 298 unsigned long dty, unsigned long prd); 299 }; 300 301 static const struct atmel_pwm_data atmel_pwm_data_v1 = { 302 .config = atmel_pwm_config_v1, 303 }; 304 305 static const struct atmel_pwm_data atmel_pwm_data_v2 = { 306 .config = atmel_pwm_config_v2, 307 }; 308 309 static const struct platform_device_id atmel_pwm_devtypes[] = { 310 { 311 .name = "at91sam9rl-pwm", 312 .driver_data = (kernel_ulong_t)&atmel_pwm_data_v1, 313 }, { 314 .name = "sama5d3-pwm", 315 .driver_data = (kernel_ulong_t)&atmel_pwm_data_v2, 316 }, { 317 /* sentinel */ 318 }, 319 }; 320 MODULE_DEVICE_TABLE(platform, atmel_pwm_devtypes); 321 322 static const struct of_device_id atmel_pwm_dt_ids[] = { 323 { 324 .compatible = "atmel,at91sam9rl-pwm", 325 .data = &atmel_pwm_data_v1, 326 }, { 327 .compatible = "atmel,sama5d3-pwm", 328 .data = &atmel_pwm_data_v2, 329 }, { 330 /* sentinel */ 331 }, 332 }; 333 MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids); 334 335 static inline const struct atmel_pwm_data * 336 atmel_pwm_get_driver_data(struct platform_device *pdev) 337 { 338 const struct platform_device_id *id; 339 340 if (pdev->dev.of_node) 341 return of_device_get_match_data(&pdev->dev); 342 343 id = platform_get_device_id(pdev); 344 345 return (struct atmel_pwm_data *)id->driver_data; 346 } 347 348 static int atmel_pwm_probe(struct platform_device *pdev) 349 { 350 const struct atmel_pwm_data *data; 351 struct atmel_pwm_chip *atmel_pwm; 352 struct resource *res; 353 int ret; 354 355 data = atmel_pwm_get_driver_data(pdev); 356 if (!data) 357 return -ENODEV; 358 359 atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL); 360 if (!atmel_pwm) 361 return -ENOMEM; 362 363 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 364 atmel_pwm->base = devm_ioremap_resource(&pdev->dev, res); 365 if (IS_ERR(atmel_pwm->base)) 366 return PTR_ERR(atmel_pwm->base); 367 368 atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL); 369 if (IS_ERR(atmel_pwm->clk)) 370 return PTR_ERR(atmel_pwm->clk); 371 372 ret = clk_prepare(atmel_pwm->clk); 373 if (ret) { 374 dev_err(&pdev->dev, "failed to prepare PWM clock\n"); 375 return ret; 376 } 377 378 atmel_pwm->chip.dev = &pdev->dev; 379 atmel_pwm->chip.ops = &atmel_pwm_ops; 380 381 if (pdev->dev.of_node) { 382 atmel_pwm->chip.of_xlate = of_pwm_xlate_with_flags; 383 atmel_pwm->chip.of_pwm_n_cells = 3; 384 } 385 386 atmel_pwm->chip.base = -1; 387 atmel_pwm->chip.npwm = 4; 388 atmel_pwm->config = data->config; 389 atmel_pwm->updated_pwms = 0; 390 mutex_init(&atmel_pwm->isr_lock); 391 392 ret = pwmchip_add(&atmel_pwm->chip); 393 if (ret < 0) { 394 dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret); 395 goto unprepare_clk; 396 } 397 398 platform_set_drvdata(pdev, atmel_pwm); 399 400 return ret; 401 402 unprepare_clk: 403 clk_unprepare(atmel_pwm->clk); 404 return ret; 405 } 406 407 static int atmel_pwm_remove(struct platform_device *pdev) 408 { 409 struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev); 410 411 clk_unprepare(atmel_pwm->clk); 412 mutex_destroy(&atmel_pwm->isr_lock); 413 414 return pwmchip_remove(&atmel_pwm->chip); 415 } 416 417 static struct platform_driver atmel_pwm_driver = { 418 .driver = { 419 .name = "atmel-pwm", 420 .of_match_table = of_match_ptr(atmel_pwm_dt_ids), 421 }, 422 .id_table = atmel_pwm_devtypes, 423 .probe = atmel_pwm_probe, 424 .remove = atmel_pwm_remove, 425 }; 426 module_platform_driver(atmel_pwm_driver); 427 428 MODULE_ALIAS("platform:atmel-pwm"); 429 MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>"); 430 MODULE_DESCRIPTION("Atmel PWM driver"); 431 MODULE_LICENSE("GPL v2"); 432