pwm-stmpe.c 7.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * Copyright (C) 2016 Linaro Ltd.
  4. *
  5. * Author: Linus Walleij <linus.walleij@linaro.org>
  6. */
  7. #include <linux/bitops.h>
  8. #include <linux/delay.h>
  9. #include <linux/err.h>
  10. #include <linux/mfd/stmpe.h>
  11. #include <linux/module.h>
  12. #include <linux/of.h>
  13. #include <linux/platform_device.h>
  14. #include <linux/pwm.h>
  15. #include <linux/slab.h>
  16. #define STMPE24XX_PWMCS 0x30
  17. #define PWMCS_EN_PWM0 BIT(0)
  18. #define PWMCS_EN_PWM1 BIT(1)
  19. #define PWMCS_EN_PWM2 BIT(2)
  20. #define STMPE24XX_PWMIC0 0x38
  21. #define STMPE24XX_PWMIC1 0x39
  22. #define STMPE24XX_PWMIC2 0x3a
  23. #define STMPE_PWM_24XX_PINBASE 21
  24. struct stmpe_pwm {
  25. struct stmpe *stmpe;
  26. struct pwm_chip chip;
  27. u8 last_duty;
  28. };
  29. static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
  30. {
  31. return container_of(chip, struct stmpe_pwm, chip);
  32. }
  33. static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  34. {
  35. struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
  36. u8 value;
  37. int ret;
  38. ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
  39. if (ret < 0) {
  40. dev_err(chip->dev, "error reading PWM#%u control\n",
  41. pwm->hwpwm);
  42. return ret;
  43. }
  44. value = ret | BIT(pwm->hwpwm);
  45. ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
  46. if (ret) {
  47. dev_err(chip->dev, "error writing PWM#%u control\n",
  48. pwm->hwpwm);
  49. return ret;
  50. }
  51. return 0;
  52. }
  53. static void stmpe_24xx_pwm_disable(struct pwm_chip *chip,
  54. struct pwm_device *pwm)
  55. {
  56. struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
  57. u8 value;
  58. int ret;
  59. ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
  60. if (ret < 0) {
  61. dev_err(chip->dev, "error reading PWM#%u control\n",
  62. pwm->hwpwm);
  63. return;
  64. }
  65. value = ret & ~BIT(pwm->hwpwm);
  66. ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
  67. if (ret) {
  68. dev_err(chip->dev, "error writing PWM#%u control\n",
  69. pwm->hwpwm);
  70. return;
  71. }
  72. }
  73. /* STMPE 24xx PWM instructions */
  74. #define SMAX 0x007f
  75. #define SMIN 0x00ff
  76. #define GTS 0x0000
  77. #define LOAD BIT(14) /* Only available on 2403 */
  78. #define RAMPUP 0x0000
  79. #define RAMPDOWN BIT(7)
  80. #define PRESCALE_512 BIT(14)
  81. #define STEPTIME_1 BIT(8)
  82. #define BRANCH (BIT(15) | BIT(13))
  83. static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  84. int duty_ns, int period_ns)
  85. {
  86. struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
  87. unsigned int i, pin;
  88. u16 program[3] = {
  89. SMAX,
  90. GTS,
  91. GTS,
  92. };
  93. u8 offset;
  94. int ret;
  95. /* Make sure we are disabled */
  96. if (pwm_is_enabled(pwm)) {
  97. stmpe_24xx_pwm_disable(chip, pwm);
  98. } else {
  99. /* Connect the PWM to the pin */
  100. pin = pwm->hwpwm;
  101. /* On STMPE2401 and 2403 pins 21,22,23 are used */
  102. if (stmpe_pwm->stmpe->partnum == STMPE2401 ||
  103. stmpe_pwm->stmpe->partnum == STMPE2403)
  104. pin += STMPE_PWM_24XX_PINBASE;
  105. ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin),
  106. STMPE_BLOCK_PWM);
  107. if (ret) {
  108. dev_err(chip->dev, "unable to connect PWM#%u to pin\n",
  109. pwm->hwpwm);
  110. return ret;
  111. }
  112. }
  113. /* STMPE24XX */
  114. switch (pwm->hwpwm) {
  115. case 0:
  116. offset = STMPE24XX_PWMIC0;
  117. break;
  118. case 1:
  119. offset = STMPE24XX_PWMIC1;
  120. break;
  121. case 2:
  122. offset = STMPE24XX_PWMIC2;
  123. break;
  124. default:
  125. /* Should not happen as npwm is 3 */
  126. return -ENODEV;
  127. }
  128. dev_dbg(chip->dev, "PWM#%u: config duty %d ns, period %d ns\n",
  129. pwm->hwpwm, duty_ns, period_ns);
  130. if (duty_ns == 0) {
  131. if (stmpe_pwm->stmpe->partnum == STMPE2401)
  132. program[0] = SMAX; /* off all the time */
  133. if (stmpe_pwm->stmpe->partnum == STMPE2403)
  134. program[0] = LOAD | 0xff; /* LOAD 0xff */
  135. stmpe_pwm->last_duty = 0x00;
  136. } else if (duty_ns == period_ns) {
  137. if (stmpe_pwm->stmpe->partnum == STMPE2401)
  138. program[0] = SMIN; /* on all the time */
  139. if (stmpe_pwm->stmpe->partnum == STMPE2403)
  140. program[0] = LOAD | 0x00; /* LOAD 0x00 */
  141. stmpe_pwm->last_duty = 0xff;
  142. } else {
  143. u8 value, last = stmpe_pwm->last_duty;
  144. unsigned long duty;
  145. /*
  146. * Counter goes from 0x00 to 0xff repeatedly at 32768 Hz,
  147. * (means a period of 30517 ns) then this is compared to the
  148. * counter from the ramp, if this is >= PWM counter the output
  149. * is high. With LOAD we can define how much of the cycle it
  150. * is on.
  151. *
  152. * Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns
  153. */
  154. /* Scale to 0..0xff */
  155. duty = duty_ns * 256;
  156. duty = DIV_ROUND_CLOSEST(duty, period_ns);
  157. value = duty;
  158. if (value == last) {
  159. /* Run the old program */
  160. if (pwm_is_enabled(pwm))
  161. stmpe_24xx_pwm_enable(chip, pwm);
  162. return 0;
  163. } else if (stmpe_pwm->stmpe->partnum == STMPE2403) {
  164. /* STMPE2403 can simply set the right PWM value */
  165. program[0] = LOAD | value;
  166. program[1] = 0x0000;
  167. } else if (stmpe_pwm->stmpe->partnum == STMPE2401) {
  168. /* STMPE2401 need a complex program */
  169. u16 incdec = 0x0000;
  170. if (last < value)
  171. /* Count up */
  172. incdec = RAMPUP | (value - last);
  173. else
  174. /* Count down */
  175. incdec = RAMPDOWN | (last - value);
  176. /* Step to desired value, smoothly */
  177. program[0] = PRESCALE_512 | STEPTIME_1 | incdec;
  178. /* Loop eternally to 0x00 */
  179. program[1] = BRANCH;
  180. }
  181. dev_dbg(chip->dev,
  182. "PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n",
  183. pwm->hwpwm, value, last, program[0], program[1],
  184. program[2]);
  185. stmpe_pwm->last_duty = value;
  186. }
  187. /*
  188. * We can write programs of up to 64 16-bit words into this channel.
  189. */
  190. for (i = 0; i < ARRAY_SIZE(program); i++) {
  191. u8 value;
  192. value = (program[i] >> 8) & 0xff;
  193. ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
  194. if (ret) {
  195. dev_err(chip->dev, "error writing register %02x: %d\n",
  196. offset, ret);
  197. return ret;
  198. }
  199. value = program[i] & 0xff;
  200. ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
  201. if (ret) {
  202. dev_err(chip->dev, "error writing register %02x: %d\n",
  203. offset, ret);
  204. return ret;
  205. }
  206. }
  207. /* If we were enabled, re-enable this PWM */
  208. if (pwm_is_enabled(pwm))
  209. stmpe_24xx_pwm_enable(chip, pwm);
  210. /* Sleep for 200ms so we're sure it will take effect */
  211. msleep(200);
  212. dev_dbg(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);
  213. return 0;
  214. }
  215. static const struct pwm_ops stmpe_24xx_pwm_ops = {
  216. .config = stmpe_24xx_pwm_config,
  217. .enable = stmpe_24xx_pwm_enable,
  218. .disable = stmpe_24xx_pwm_disable,
  219. .owner = THIS_MODULE,
  220. };
  221. static int __init stmpe_pwm_probe(struct platform_device *pdev)
  222. {
  223. struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
  224. struct stmpe_pwm *pwm;
  225. int ret;
  226. pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
  227. if (!pwm)
  228. return -ENOMEM;
  229. pwm->stmpe = stmpe;
  230. pwm->chip.dev = &pdev->dev;
  231. pwm->chip.base = -1;
  232. if (stmpe->partnum == STMPE2401 || stmpe->partnum == STMPE2403) {
  233. pwm->chip.ops = &stmpe_24xx_pwm_ops;
  234. pwm->chip.npwm = 3;
  235. } else {
  236. if (stmpe->partnum == STMPE1601)
  237. dev_err(&pdev->dev, "STMPE1601 not yet supported\n");
  238. else
  239. dev_err(&pdev->dev, "Unknown STMPE PWM\n");
  240. return -ENODEV;
  241. }
  242. ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM);
  243. if (ret)
  244. return ret;
  245. ret = pwmchip_add(&pwm->chip);
  246. if (ret) {
  247. stmpe_disable(stmpe, STMPE_BLOCK_PWM);
  248. return ret;
  249. }
  250. platform_set_drvdata(pdev, pwm);
  251. return 0;
  252. }
  253. static struct platform_driver stmpe_pwm_driver = {
  254. .driver = {
  255. .name = "stmpe-pwm",
  256. },
  257. };
  258. builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);