pwm-ep93xx.c 4.9 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * PWM framework driver for Cirrus Logic EP93xx
  4. *
  5. * Copyright (c) 2009 Matthieu Crapet <[email protected]>
  6. * Copyright (c) 2009, 2013 H Hartley Sweeten <[email protected]>
  7. *
  8. * EP9301/02 have only one channel:
  9. * platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
  10. *
  11. * EP9307 has only one channel:
  12. * platform device ep93xx-pwm.0 - PWMOUT
  13. *
  14. * EP9312/15 have two channels:
  15. * platform device ep93xx-pwm.0 - PWMOUT
  16. * platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
  17. */
  18. #include <linux/module.h>
  19. #include <linux/platform_device.h>
  20. #include <linux/slab.h>
  21. #include <linux/clk.h>
  22. #include <linux/err.h>
  23. #include <linux/io.h>
  24. #include <linux/pwm.h>
  25. #include <asm/div64.h>
  26. #include <linux/soc/cirrus/ep93xx.h> /* for ep93xx_pwm_{acquire,release}_gpio() */
  27. #define EP93XX_PWMx_TERM_COUNT 0x00
  28. #define EP93XX_PWMx_DUTY_CYCLE 0x04
  29. #define EP93XX_PWMx_ENABLE 0x08
  30. #define EP93XX_PWMx_INVERT 0x0c
  31. struct ep93xx_pwm {
  32. void __iomem *base;
  33. struct clk *clk;
  34. struct pwm_chip chip;
  35. };
  36. static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
  37. {
  38. return container_of(chip, struct ep93xx_pwm, chip);
  39. }
  40. static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  41. {
  42. struct platform_device *pdev = to_platform_device(chip->dev);
  43. return ep93xx_pwm_acquire_gpio(pdev);
  44. }
  45. static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  46. {
  47. struct platform_device *pdev = to_platform_device(chip->dev);
  48. ep93xx_pwm_release_gpio(pdev);
  49. }
  50. static int ep93xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  51. const struct pwm_state *state)
  52. {
  53. int ret;
  54. struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
  55. bool enabled = state->enabled;
  56. void __iomem *base = ep93xx_pwm->base;
  57. unsigned long long c;
  58. unsigned long period_cycles;
  59. unsigned long duty_cycles;
  60. unsigned long term;
  61. if (state->polarity != pwm->state.polarity) {
  62. if (enabled) {
  63. writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  64. clk_disable_unprepare(ep93xx_pwm->clk);
  65. enabled = false;
  66. }
  67. /*
  68. * The clock needs to be enabled to access the PWM registers.
  69. * Polarity can only be changed when the PWM is disabled.
  70. */
  71. ret = clk_prepare_enable(ep93xx_pwm->clk);
  72. if (ret)
  73. return ret;
  74. if (state->polarity == PWM_POLARITY_INVERSED)
  75. writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  76. else
  77. writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
  78. clk_disable_unprepare(ep93xx_pwm->clk);
  79. }
  80. if (!state->enabled) {
  81. if (enabled) {
  82. writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  83. clk_disable_unprepare(ep93xx_pwm->clk);
  84. }
  85. return 0;
  86. }
  87. /*
  88. * The clock needs to be enabled to access the PWM registers.
  89. * Configuration can be changed at any time.
  90. */
  91. if (!pwm_is_enabled(pwm)) {
  92. ret = clk_prepare_enable(ep93xx_pwm->clk);
  93. if (ret)
  94. return ret;
  95. }
  96. c = clk_get_rate(ep93xx_pwm->clk);
  97. c *= state->period;
  98. do_div(c, 1000000000);
  99. period_cycles = c;
  100. c = period_cycles;
  101. c *= state->duty_cycle;
  102. do_div(c, state->period);
  103. duty_cycles = c;
  104. if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
  105. term = readw(base + EP93XX_PWMx_TERM_COUNT);
  106. /* Order is important if PWM is running */
  107. if (period_cycles > term) {
  108. writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
  109. writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
  110. } else {
  111. writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
  112. writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
  113. }
  114. ret = 0;
  115. } else {
  116. ret = -EINVAL;
  117. }
  118. if (!pwm_is_enabled(pwm))
  119. clk_disable_unprepare(ep93xx_pwm->clk);
  120. if (ret)
  121. return ret;
  122. if (!enabled) {
  123. ret = clk_prepare_enable(ep93xx_pwm->clk);
  124. if (ret)
  125. return ret;
  126. writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
  127. }
  128. return 0;
  129. }
  130. static const struct pwm_ops ep93xx_pwm_ops = {
  131. .request = ep93xx_pwm_request,
  132. .free = ep93xx_pwm_free,
  133. .apply = ep93xx_pwm_apply,
  134. .owner = THIS_MODULE,
  135. };
  136. static int ep93xx_pwm_probe(struct platform_device *pdev)
  137. {
  138. struct ep93xx_pwm *ep93xx_pwm;
  139. int ret;
  140. ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
  141. if (!ep93xx_pwm)
  142. return -ENOMEM;
  143. ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
  144. if (IS_ERR(ep93xx_pwm->base))
  145. return PTR_ERR(ep93xx_pwm->base);
  146. ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
  147. if (IS_ERR(ep93xx_pwm->clk))
  148. return PTR_ERR(ep93xx_pwm->clk);
  149. ep93xx_pwm->chip.dev = &pdev->dev;
  150. ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
  151. ep93xx_pwm->chip.npwm = 1;
  152. ret = devm_pwmchip_add(&pdev->dev, &ep93xx_pwm->chip);
  153. if (ret < 0)
  154. return ret;
  155. return 0;
  156. }
  157. static struct platform_driver ep93xx_pwm_driver = {
  158. .driver = {
  159. .name = "ep93xx-pwm",
  160. },
  161. .probe = ep93xx_pwm_probe,
  162. };
  163. module_platform_driver(ep93xx_pwm_driver);
  164. MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
  165. MODULE_AUTHOR("Matthieu Crapet <[email protected]>");
  166. MODULE_AUTHOR("H Hartley Sweeten <[email protected]>");
  167. MODULE_ALIAS("platform:ep93xx-pwm");
  168. MODULE_LICENSE("GPL");