pwm-bcm2835.c 4.9 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
  4. */
  5. #include <linux/clk.h>
  6. #include <linux/err.h>
  7. #include <linux/io.h>
  8. #include <linux/module.h>
  9. #include <linux/of.h>
  10. #include <linux/platform_device.h>
  11. #include <linux/pwm.h>
  12. #define PWM_CONTROL 0x000
  13. #define PWM_CONTROL_SHIFT(x) ((x) * 8)
  14. #define PWM_CONTROL_MASK 0xff
  15. #define PWM_MODE 0x80 /* set timer in PWM mode */
  16. #define PWM_ENABLE (1 << 0)
  17. #define PWM_POLARITY (1 << 4)
  18. #define PERIOD(x) (((x) * 0x10) + 0x10)
  19. #define DUTY(x) (((x) * 0x10) + 0x14)
  20. #define PERIOD_MIN 0x2
  21. struct bcm2835_pwm {
  22. struct pwm_chip chip;
  23. struct device *dev;
  24. void __iomem *base;
  25. struct clk *clk;
  26. };
  27. static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
  28. {
  29. return container_of(chip, struct bcm2835_pwm, chip);
  30. }
  31. static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  32. {
  33. struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  34. u32 value;
  35. value = readl(pc->base + PWM_CONTROL);
  36. value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
  37. value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
  38. writel(value, pc->base + PWM_CONTROL);
  39. return 0;
  40. }
  41. static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  42. {
  43. struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  44. u32 value;
  45. value = readl(pc->base + PWM_CONTROL);
  46. value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
  47. writel(value, pc->base + PWM_CONTROL);
  48. }
  49. static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  50. int duty_ns, int period_ns)
  51. {
  52. struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  53. unsigned long rate = clk_get_rate(pc->clk);
  54. unsigned long scaler;
  55. u32 period;
  56. if (!rate) {
  57. dev_err(pc->dev, "failed to get clock rate\n");
  58. return -EINVAL;
  59. }
  60. scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
  61. period = DIV_ROUND_CLOSEST(period_ns, scaler);
  62. if (period < PERIOD_MIN)
  63. return -EINVAL;
  64. writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
  65. pc->base + DUTY(pwm->hwpwm));
  66. writel(period, pc->base + PERIOD(pwm->hwpwm));
  67. return 0;
  68. }
  69. static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  70. {
  71. struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  72. u32 value;
  73. value = readl(pc->base + PWM_CONTROL);
  74. value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
  75. writel(value, pc->base + PWM_CONTROL);
  76. return 0;
  77. }
  78. static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  79. {
  80. struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  81. u32 value;
  82. value = readl(pc->base + PWM_CONTROL);
  83. value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
  84. writel(value, pc->base + PWM_CONTROL);
  85. }
  86. static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
  87. enum pwm_polarity polarity)
  88. {
  89. struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
  90. u32 value;
  91. value = readl(pc->base + PWM_CONTROL);
  92. if (polarity == PWM_POLARITY_NORMAL)
  93. value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
  94. else
  95. value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
  96. writel(value, pc->base + PWM_CONTROL);
  97. return 0;
  98. }
  99. static const struct pwm_ops bcm2835_pwm_ops = {
  100. .request = bcm2835_pwm_request,
  101. .free = bcm2835_pwm_free,
  102. .config = bcm2835_pwm_config,
  103. .enable = bcm2835_pwm_enable,
  104. .disable = bcm2835_pwm_disable,
  105. .set_polarity = bcm2835_set_polarity,
  106. .owner = THIS_MODULE,
  107. };
  108. static int bcm2835_pwm_probe(struct platform_device *pdev)
  109. {
  110. struct bcm2835_pwm *pc;
  111. struct resource *res;
  112. int ret;
  113. pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
  114. if (!pc)
  115. return -ENOMEM;
  116. pc->dev = &pdev->dev;
  117. res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  118. pc->base = devm_ioremap_resource(&pdev->dev, res);
  119. if (IS_ERR(pc->base))
  120. return PTR_ERR(pc->base);
  121. pc->clk = devm_clk_get(&pdev->dev, NULL);
  122. if (IS_ERR(pc->clk))
  123. return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk),
  124. "clock not found\n");
  125. ret = clk_prepare_enable(pc->clk);
  126. if (ret)
  127. return ret;
  128. pc->chip.dev = &pdev->dev;
  129. pc->chip.ops = &bcm2835_pwm_ops;
  130. pc->chip.base = -1;
  131. pc->chip.npwm = 2;
  132. pc->chip.of_xlate = of_pwm_xlate_with_flags;
  133. pc->chip.of_pwm_n_cells = 3;
  134. platform_set_drvdata(pdev, pc);
  135. ret = pwmchip_add(&pc->chip);
  136. if (ret < 0)
  137. goto add_fail;
  138. return 0;
  139. add_fail:
  140. clk_disable_unprepare(pc->clk);
  141. return ret;
  142. }
  143. static int bcm2835_pwm_remove(struct platform_device *pdev)
  144. {
  145. struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
  146. clk_disable_unprepare(pc->clk);
  147. return pwmchip_remove(&pc->chip);
  148. }
  149. static const struct of_device_id bcm2835_pwm_of_match[] = {
  150. { .compatible = "brcm,bcm2835-pwm", },
  151. { /* sentinel */ }
  152. };
  153. MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
  154. static struct platform_driver bcm2835_pwm_driver = {
  155. .driver = {
  156. .name = "bcm2835-pwm",
  157. .of_match_table = bcm2835_pwm_of_match,
  158. },
  159. .probe = bcm2835_pwm_probe,
  160. .remove = bcm2835_pwm_remove,
  161. };
  162. module_platform_driver(bcm2835_pwm_driver);
  163. MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
  164. MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
  165. MODULE_LICENSE("GPL v2");