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/slab.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/device.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/completion.h>
  26
  27 #include <linux/mfd/pcf50633/core.h>
  28 #include <linux/mfd/pcf50633/adc.h>
  29
  30 struct pcf50633_adc_request {
  31         int mux;
  32         int avg;
  33         void (*callback)(struct pcf50633 *, void *, int);
  34         void *callback_param;
  35 };
  36
  37 struct pcf50633_adc_sync_request {
  38         int result;
  39         struct completion completion;
  40 };
  41
  42 #define PCF50633_MAX_ADC_FIFO_DEPTH 8
  43
  44 struct pcf50633_adc {
  45         struct pcf50633 *pcf;
  46
  47         /* Private stuff */
  48         struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH];
  49         int queue_head;
  50         int queue_tail;
  51         struct mutex queue_mutex;
  52 };
  53
  54 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
  55 {
  56         return platform_get_drvdata(pcf->adc_pdev);
  57 }
  58
  59 static void adc_setup(struct pcf50633 *pcf, int channel, int avg)
  60 {
  61         channel &= PCF50633_ADCC1_ADCMUX_MASK;
  62
  63         /* kill ratiometric, but enable ACCSW biasing */
  64         pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00);
  65         pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01);
  66
  67         /* start ADC conversion on selected channel */
  68         pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg |
  69                     PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT);
  70 }
  71
  72 static void trigger_next_adc_job_if_any(struct pcf50633 *pcf)
  73 {
  74         struct pcf50633_adc *adc = __to_adc(pcf);
  75         int head;
  76
  77         head = adc->queue_head;
  78
  79         if (!adc->queue[head])
  80                 return;
  81
  82         adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg);
  83 }
  84
  85 static int
  86 adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req)
  87 {
  88         struct pcf50633_adc *adc = __to_adc(pcf);
  89         int head, tail;
  90
  91         mutex_lock(&adc->queue_mutex);
  92
  93         head = adc->queue_head;
  94         tail = adc->queue_tail;
  95
  96         if (adc->queue[tail]) {
  97                 mutex_unlock(&adc->queue_mutex);
  98                 dev_err(pcf->dev, "ADC queue is full, dropping request\n");
  99                 return -EBUSY;
 100         }
 101
 102         adc->queue[tail] = req;
 103         if (head == tail)
 104                 trigger_next_adc_job_if_any(pcf);
 105         adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
 106
 107         mutex_unlock(&adc->queue_mutex);
 108
 109         return 0;
 110 }
 111
 112 static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param,
 113         int result)
 114 {
 115         struct pcf50633_adc_sync_request *req = param;
 116
 117         req->result = result;
 118         complete(&req->completion);
 119 }
 120
 121 int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg)
 122 {
 123         struct pcf50633_adc_sync_request req;
 124         int ret;
 125
 126         init_completion(&req.completion);
 127
 128         ret = pcf50633_adc_async_read(pcf, mux, avg,
 129                 pcf50633_adc_sync_read_callback, &req);
 130         if (ret)
 131                 return ret;
 132
 133         wait_for_completion(&req.completion);
 134
 135         return req.result;
 136 }
 137 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
 138
 139 int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
 140                              void (*callback)(struct pcf50633 *, void *, int),
 141                              void *callback_param)
 142 {
 143         struct pcf50633_adc_request *req;
 144
 145         /* req is freed when the result is ready, in interrupt handler */
 146         req = kmalloc(sizeof(*req), GFP_KERNEL);
 147         if (!req)
 148                 return -ENOMEM;
 149
 150         req->mux = mux;
 151         req->avg = avg;
 152         req->callback = callback;
 153         req->callback_param = callback_param;
 154
 155         return adc_enqueue_request(pcf, req);
 156 }
 157 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
 158
 159 static int adc_result(struct pcf50633 *pcf)
 160 {
 161         u8 adcs1, adcs3;
 162         u16 result;
 163
 164         adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
 165         adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
 166         result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
 167
 168         dev_dbg(pcf->dev, "adc result = %d\n", result);
 169
 170         return result;
 171 }
 172
 173 static void pcf50633_adc_irq(int irq, void *data)
 174 {
 175         struct pcf50633_adc *adc = data;
 176         struct pcf50633 *pcf = adc->pcf;
 177         struct pcf50633_adc_request *req;
 178         int head, res;
 179
 180         mutex_lock(&adc->queue_mutex);
 181         head = adc->queue_head;
 182
 183         req = adc->queue[head];
 184         if (WARN_ON(!req)) {
 185                 dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
 186                 mutex_unlock(&adc->queue_mutex);
 187                 return;
 188         }
 189         adc->queue[head] = NULL;
 190         adc->queue_head = (head + 1) &
 191                                       (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
 192
 193         res = adc_result(pcf);
 194         trigger_next_adc_job_if_any(pcf);
 195
 196         mutex_unlock(&adc->queue_mutex);
 197
 198         req->callback(pcf, req->callback_param, res);
 199         kfree(req);
 200 }
 201
 202 static int pcf50633_adc_probe(struct platform_device *pdev)
 203 {
 204         struct pcf50633_adc *adc;
 205
 206         adc = kzalloc(sizeof(*adc), GFP_KERNEL);
 207         if (!adc)
 208                 return -ENOMEM;
 209
 210         adc->pcf = dev_to_pcf50633(pdev->dev.parent);
 211         platform_set_drvdata(pdev, adc);
 212
 213         pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
 214                                         pcf50633_adc_irq, adc);
 215
 216         mutex_init(&adc->queue_mutex);
 217
 218         return 0;
 219 }
 220
 221 static int pcf50633_adc_remove(struct platform_device *pdev)
 222 {
 223         struct pcf50633_adc *adc = platform_get_drvdata(pdev);
 224         int i, head;
 225
 226         pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
 227
 228         mutex_lock(&adc->queue_mutex);
 229         head = adc->queue_head;
 230
 231         if (WARN_ON(adc->queue[head]))
 232                 dev_err(adc->pcf->dev,
 233                         "adc driver removed with request pending\n");
 234
 235         for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
 236                 kfree(adc->queue[i]);
 237
 238         mutex_unlock(&adc->queue_mutex);
 239         kfree(adc);
 240
 241         return 0;
 242 }
 243
 244 static struct platform_driver pcf50633_adc_driver = {
 245         .driver = {
 246                 .name = "pcf50633-adc",
 247         },
 248         .probe = pcf50633_adc_probe,
 249         .remove = pcf50633_adc_remove,
 250 };
 251
 252 module_platform_driver(pcf50633_adc_driver);
 253
 254 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
 255 MODULE_DESCRIPTION("PCF50633 adc driver");
 256 MODULE_LICENSE("GPL");
 257 MODULE_ALIAS("platform:pcf50633-adc");
 258