drivers/mfd/pcf50633-adc.c

   1 /* NXP PCF50633 ADC Driver
   2  *
   3  * (C) 2006-2008 by Openmoko, Inc.
   4  * Author: Balaji Rao <balajirrao@openmoko.org>
   5  * All rights reserved.
   6  *
   7  * Broken down from monstrous PCF50633 driver mainly by
   8  * Harald Welte, Andy Green and Werner Almesberger
   9  *
  10  *  This program is free software; you can redistribute  it and/or modify it
  11  *  under  the terms of  the GNU General  Public License as published by the
  12  *  Free Software Foundation;  either version 2 of the  License, or (at your
  13  *  option) any later version.
  14  *
  15  *  NOTE: This driver does not yet support subtractive ADC mode, which means
  16  *  you can do only one measurement per read request.
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/init.h>
  22 #include <linux/device.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/completion.h>
  25
  26 #include <linux/mfd/pcf50633/core.h>
  27 #include <linux/mfd/pcf50633/adc.h>
  28
  29 struct pcf50633_adc_request {
  30         int mux;
  31         int avg;
  32         int result;
  33         void (*callback)(struct pcf50633 *, void *, int);
  34         void *callback_param;
  35
  36         /* Used in case of sync requests */
  37         struct completion completion;
  38
  39 };
  40
  41 #define PCF50633_MAX_ADC_FIFO_DEPTH 8
  42
  43 struct pcf50633_adc {
  44         struct pcf50633 *pcf;
  45
  46         /* Private stuff */
  47         struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH];
  48         int queue_head;
  49         int queue_tail;
  50         struct mutex queue_mutex;
  51 };
  52
  53 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
  54 {
  55         return platform_get_drvdata(pcf->adc_pdev);
  56 }
  57
  58 static void adc_setup(struct pcf50633 *pcf, int channel, int avg)
  59 {
  60         channel &= PCF50633_ADCC1_ADCMUX_MASK;
  61
  62         /* kill ratiometric, but enable ACCSW biasing */
  63         pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00);
  64         pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01);
  65
  66         /* start ADC conversion on selected channel */
  67         pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg |
  68                     PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT);
  69 }
  70
  71 static void trigger_next_adc_job_if_any(struct pcf50633 *pcf)
  72 {
  73         struct pcf50633_adc *adc = __to_adc(pcf);
  74         int head;
  75
  76         head = adc->queue_head;
  77
  78         if (!adc->queue[head])
  79                 return;
  80
  81         adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg);
  82 }
  83
  84 static int
  85 adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req)
  86 {
  87         struct pcf50633_adc *adc = __to_adc(pcf);
  88         int head, tail;
  89
  90         mutex_lock(&adc->queue_mutex);
  91
  92         head = adc->queue_head;
  93         tail = adc->queue_tail;
  94
  95         if (adc->queue[tail]) {
  96                 mutex_unlock(&adc->queue_mutex);
  97                 dev_err(pcf->dev, "ADC queue is full, dropping request\n");
  98                 return -EBUSY;
  99         }
 100
 101         adc->queue[tail] = req;
 102         if (head == tail)
 103                 trigger_next_adc_job_if_any(pcf);
 104         adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
 105
 106         mutex_unlock(&adc->queue_mutex);
 107
 108         return 0;
 109 }
 110
 111 static void
 112 pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param, int result)
 113 {
 114         struct pcf50633_adc_request *req = param;
 115
 116         req->result = result;
 117         complete(&req->completion);
 118 }
 119
 120 int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg)
 121 {
 122         struct pcf50633_adc_request *req;
 123         int err;
 124
 125         /* req is freed when the result is ready, in interrupt handler */
 126         req = kzalloc(sizeof(*req), GFP_KERNEL);
 127         if (!req)
 128                 return -ENOMEM;
 129
 130         req->mux = mux;
 131         req->avg = avg;
 132         req->callback =  pcf50633_adc_sync_read_callback;
 133         req->callback_param = req;
 134
 135         init_completion(&req->completion);
 136         err = adc_enqueue_request(pcf, req);
 137         if (err)
 138                 return err;
 139
 140         wait_for_completion(&req->completion);
 141
 142         /* FIXME by this time req might be already freed */
 143         return req->result;
 144 }
 145 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
 146
 147 int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
 148                              void (*callback)(struct pcf50633 *, void *, int),
 149                              void *callback_param)
 150 {
 151         struct pcf50633_adc_request *req;
 152
 153         /* req is freed when the result is ready, in interrupt handler */
 154         req = kmalloc(sizeof(*req), GFP_KERNEL);
 155         if (!req)
 156                 return -ENOMEM;
 157
 158         req->mux = mux;
 159         req->avg = avg;
 160         req->callback = callback;
 161         req->callback_param = callback_param;
 162
 163         return adc_enqueue_request(pcf, req);
 164 }
 165 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
 166
 167 static int adc_result(struct pcf50633 *pcf)
 168 {
 169         u8 adcs1, adcs3;
 170         u16 result;
 171
 172         adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
 173         adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
 174         result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
 175
 176         dev_dbg(pcf->dev, "adc result = %d\n", result);
 177
 178         return result;
 179 }
 180
 181 static void pcf50633_adc_irq(int irq, void *data)
 182 {
 183         struct pcf50633_adc *adc = data;
 184         struct pcf50633 *pcf = adc->pcf;
 185         struct pcf50633_adc_request *req;
 186         int head, res;
 187
 188         mutex_lock(&adc->queue_mutex);
 189         head = adc->queue_head;
 190
 191         req = adc->queue[head];
 192         if (WARN_ON(!req)) {
 193                 dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
 194                 mutex_unlock(&adc->queue_mutex);
 195                 return;
 196         }
 197         adc->queue[head] = NULL;
 198         adc->queue_head = (head + 1) &
 199                                       (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
 200
 201         res = adc_result(pcf);
 202         trigger_next_adc_job_if_any(pcf);
 203
 204         mutex_unlock(&adc->queue_mutex);
 205
 206         req->callback(pcf, req->callback_param, res);
 207         kfree(req);
 208 }
 209
 210 static int __devinit pcf50633_adc_probe(struct platform_device *pdev)
 211 {
 212         struct pcf50633_adc *adc;
 213
 214         adc = kzalloc(sizeof(*adc), GFP_KERNEL);
 215         if (!adc)
 216                 return -ENOMEM;
 217
 218         adc->pcf = dev_to_pcf50633(pdev->dev.parent);
 219         platform_set_drvdata(pdev, adc);
 220
 221         pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
 222                                         pcf50633_adc_irq, adc);
 223
 224         mutex_init(&adc->queue_mutex);
 225
 226         return 0;
 227 }
 228
 229 static int __devexit pcf50633_adc_remove(struct platform_device *pdev)
 230 {
 231         struct pcf50633_adc *adc = platform_get_drvdata(pdev);
 232         int i, head;
 233
 234         pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
 235
 236         mutex_lock(&adc->queue_mutex);
 237         head = adc->queue_head;
 238
 239         if (WARN_ON(adc->queue[head]))
 240                 dev_err(adc->pcf->dev,
 241                         "adc driver removed with request pending\n");
 242
 243         for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
 244                 kfree(adc->queue[i]);
 245
 246         mutex_unlock(&adc->queue_mutex);
 247         kfree(adc);
 248
 249         return 0;
 250 }
 251
 252 static struct platform_driver pcf50633_adc_driver = {
 253         .driver = {
 254                 .name = "pcf50633-adc",
 255         },
 256         .probe = pcf50633_adc_probe,
 257         .remove = __devexit_p(pcf50633_adc_remove),
 258 };
 259
 260 static int __init pcf50633_adc_init(void)
 261 {
 262         return platform_driver_register(&pcf50633_adc_driver);
 263 }
 264 module_init(pcf50633_adc_init);
 265
 266 static void __exit pcf50633_adc_exit(void)
 267 {
 268         platform_driver_unregister(&pcf50633_adc_driver);
 269 }
 270 module_exit(pcf50633_adc_exit);
 271
 272 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
 273 MODULE_DESCRIPTION("PCF50633 adc driver");
 274 MODULE_LICENSE("GPL");
 275 MODULE_ALIAS("platform:pcf50633-adc");
 276