pcf50633-adc.c 5.7 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /* NXP PCF50633 ADC Driver
  3. *
  4. * (C) 2006-2008 by Openmoko, Inc.
  5. * Author: Balaji Rao <balajirrao@openmoko.org>
  6. * All rights reserved.
  7. *
  8. * Broken down from monstrous PCF50633 driver mainly by
  9. * Harald Welte, Andy Green and Werner Almesberger
  10. *
  11. * NOTE: This driver does not yet support subtractive ADC mode, which means
  12. * you can do only one measurement per read request.
  13. */
  14. #include <linux/kernel.h>
  15. #include <linux/slab.h>
  16. #include <linux/module.h>
  17. #include <linux/device.h>
  18. #include <linux/platform_device.h>
  19. #include <linux/completion.h>
  20. #include <linux/mfd/pcf50633/core.h>
  21. #include <linux/mfd/pcf50633/adc.h>
  22. struct pcf50633_adc_request {
  23. int mux;
  24. int avg;
  25. void (*callback)(struct pcf50633 *, void *, int);
  26. void *callback_param;
  27. };
  28. struct pcf50633_adc_sync_request {
  29. int result;
  30. struct completion completion;
  31. };
  32. #define PCF50633_MAX_ADC_FIFO_DEPTH 8
  33. struct pcf50633_adc {
  34. struct pcf50633 *pcf;
  35. /* Private stuff */
  36. struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH];
  37. int queue_head;
  38. int queue_tail;
  39. struct mutex queue_mutex;
  40. };
  41. static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
  42. {
  43. return platform_get_drvdata(pcf->adc_pdev);
  44. }
  45. static void adc_setup(struct pcf50633 *pcf, int channel, int avg)
  46. {
  47. channel &= PCF50633_ADCC1_ADCMUX_MASK;
  48. /* kill ratiometric, but enable ACCSW biasing */
  49. pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00);
  50. pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01);
  51. /* start ADC conversion on selected channel */
  52. pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg |
  53. PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT);
  54. }
  55. static void trigger_next_adc_job_if_any(struct pcf50633 *pcf)
  56. {
  57. struct pcf50633_adc *adc = __to_adc(pcf);
  58. int head;
  59. head = adc->queue_head;
  60. if (!adc->queue[head])
  61. return;
  62. adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg);
  63. }
  64. static int
  65. adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req)
  66. {
  67. struct pcf50633_adc *adc = __to_adc(pcf);
  68. int head, tail;
  69. mutex_lock(&adc->queue_mutex);
  70. head = adc->queue_head;
  71. tail = adc->queue_tail;
  72. if (adc->queue[tail]) {
  73. mutex_unlock(&adc->queue_mutex);
  74. dev_err(pcf->dev, "ADC queue is full, dropping request\n");
  75. return -EBUSY;
  76. }
  77. adc->queue[tail] = req;
  78. if (head == tail)
  79. trigger_next_adc_job_if_any(pcf);
  80. adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
  81. mutex_unlock(&adc->queue_mutex);
  82. return 0;
  83. }
  84. static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param,
  85. int result)
  86. {
  87. struct pcf50633_adc_sync_request *req = param;
  88. req->result = result;
  89. complete(&req->completion);
  90. }
  91. int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg)
  92. {
  93. struct pcf50633_adc_sync_request req;
  94. int ret;
  95. init_completion(&req.completion);
  96. ret = pcf50633_adc_async_read(pcf, mux, avg,
  97. pcf50633_adc_sync_read_callback, &req);
  98. if (ret)
  99. return ret;
  100. wait_for_completion(&req.completion);
  101. return req.result;
  102. }
  103. EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
  104. int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
  105. void (*callback)(struct pcf50633 *, void *, int),
  106. void *callback_param)
  107. {
  108. struct pcf50633_adc_request *req;
  109. /* req is freed when the result is ready, in interrupt handler */
  110. req = kmalloc(sizeof(*req), GFP_KERNEL);
  111. if (!req)
  112. return -ENOMEM;
  113. req->mux = mux;
  114. req->avg = avg;
  115. req->callback = callback;
  116. req->callback_param = callback_param;
  117. return adc_enqueue_request(pcf, req);
  118. }
  119. EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
  120. static int adc_result(struct pcf50633 *pcf)
  121. {
  122. u8 adcs1, adcs3;
  123. u16 result;
  124. adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
  125. adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
  126. result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
  127. dev_dbg(pcf->dev, "adc result = %d\n", result);
  128. return result;
  129. }
  130. static void pcf50633_adc_irq(int irq, void *data)
  131. {
  132. struct pcf50633_adc *adc = data;
  133. struct pcf50633 *pcf = adc->pcf;
  134. struct pcf50633_adc_request *req;
  135. int head, res;
  136. mutex_lock(&adc->queue_mutex);
  137. head = adc->queue_head;
  138. req = adc->queue[head];
  139. if (WARN_ON(!req)) {
  140. dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
  141. mutex_unlock(&adc->queue_mutex);
  142. return;
  143. }
  144. adc->queue[head] = NULL;
  145. adc->queue_head = (head + 1) &
  146. (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
  147. res = adc_result(pcf);
  148. trigger_next_adc_job_if_any(pcf);
  149. mutex_unlock(&adc->queue_mutex);
  150. req->callback(pcf, req->callback_param, res);
  151. kfree(req);
  152. }
  153. static int pcf50633_adc_probe(struct platform_device *pdev)
  154. {
  155. struct pcf50633_adc *adc;
  156. adc = devm_kzalloc(&pdev->dev, sizeof(*adc), GFP_KERNEL);
  157. if (!adc)
  158. return -ENOMEM;
  159. adc->pcf = dev_to_pcf50633(pdev->dev.parent);
  160. platform_set_drvdata(pdev, adc);
  161. pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
  162. pcf50633_adc_irq, adc);
  163. mutex_init(&adc->queue_mutex);
  164. return 0;
  165. }
  166. static int pcf50633_adc_remove(struct platform_device *pdev)
  167. {
  168. struct pcf50633_adc *adc = platform_get_drvdata(pdev);
  169. int i, head;
  170. pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
  171. mutex_lock(&adc->queue_mutex);
  172. head = adc->queue_head;
  173. if (WARN_ON(adc->queue[head]))
  174. dev_err(adc->pcf->dev,
  175. "adc driver removed with request pending\n");
  176. for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
  177. kfree(adc->queue[i]);
  178. mutex_unlock(&adc->queue_mutex);
  179. return 0;
  180. }
  181. static struct platform_driver pcf50633_adc_driver = {
  182. .driver = {
  183. .name = "pcf50633-adc",
  184. },
  185. .probe = pcf50633_adc_probe,
  186. .remove = pcf50633_adc_remove,
  187. };
  188. module_platform_driver(pcf50633_adc_driver);
  189. MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
  190. MODULE_DESCRIPTION("PCF50633 adc driver");
  191. MODULE_LICENSE("GPL");
  192. MODULE_ALIAS("platform:pcf50633-adc");