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/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         void (*callback)(struct pcf50633 *, void *, int);
  33         void *callback_param;
  34 };
  35
  36 struct pcf50633_adc_sync_request {
  37         int result;
  38         struct completion completion;
  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 pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param,
 112         int result)
 113 {
 114         struct pcf50633_adc_sync_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_sync_request req;
 123         int ret;
 124
 125         init_completion(&req.completion);
 126
 127         ret = pcf50633_adc_async_read(pcf, mux, avg,
 128                 pcf50633_adc_sync_read_callback, &req);
 129         if (ret)
 130                 return ret;
 131
 132         wait_for_completion(&req.completion);
 133
 134         return req.result;
 135 }
 136 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
 137
 138 int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
 139                              void (*callback)(struct pcf50633 *, void *, int),
 140                              void *callback_param)
 141 {
 142         struct pcf50633_adc_request *req;
 143
 144         /* req is freed when the result is ready, in interrupt handler */
 145         req = kmalloc(sizeof(*req), GFP_KERNEL);
 146         if (!req)
 147                 return -ENOMEM;
 148
 149         req->mux = mux;
 150         req->avg = avg;
 151         req->callback = callback;
 152         req->callback_param = callback_param;
 153
 154         return adc_enqueue_request(pcf, req);
 155 }
 156 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
 157
 158 static int adc_result(struct pcf50633 *pcf)
 159 {
 160         u8 adcs1, adcs3;
 161         u16 result;
 162
 163         adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
 164         adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
 165         result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
 166
 167         dev_dbg(pcf->dev, "adc result = %d\n", result);
 168
 169         return result;
 170 }
 171
 172 static void pcf50633_adc_irq(int irq, void *data)
 173 {
 174         struct pcf50633_adc *adc = data;
 175         struct pcf50633 *pcf = adc->pcf;
 176         struct pcf50633_adc_request *req;
 177         int head, res;
 178
 179         mutex_lock(&adc->queue_mutex);
 180         head = adc->queue_head;
 181
 182         req = adc->queue[head];
 183         if (WARN_ON(!req)) {
 184                 dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
 185                 mutex_unlock(&adc->queue_mutex);
 186                 return;
 187         }
 188         adc->queue[head] = NULL;
 189         adc->queue_head = (head + 1) &
 190                                       (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
 191
 192         res = adc_result(pcf);
 193         trigger_next_adc_job_if_any(pcf);
 194
 195         mutex_unlock(&adc->queue_mutex);
 196
 197         req->callback(pcf, req->callback_param, res);
 198         kfree(req);
 199 }
 200
 201 static int pcf50633_adc_probe(struct platform_device *pdev)
 202 {
 203         struct pcf50633_adc *adc;
 204
 205         adc = devm_kzalloc(&pdev->dev, sizeof(*adc), GFP_KERNEL);
 206         if (!adc)
 207                 return -ENOMEM;
 208
 209         adc->pcf = dev_to_pcf50633(pdev->dev.parent);
 210         platform_set_drvdata(pdev, adc);
 211
 212         pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
 213                                         pcf50633_adc_irq, adc);
 214
 215         mutex_init(&adc->queue_mutex);
 216
 217         return 0;
 218 }
 219
 220 static int pcf50633_adc_remove(struct platform_device *pdev)
 221 {
 222         struct pcf50633_adc *adc = platform_get_drvdata(pdev);
 223         int i, head;
 224
 225         pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
 226
 227         mutex_lock(&adc->queue_mutex);
 228         head = adc->queue_head;
 229
 230         if (WARN_ON(adc->queue[head]))
 231                 dev_err(adc->pcf->dev,
 232                         "adc driver removed with request pending\n");
 233
 234         for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
 235                 kfree(adc->queue[i]);
 236
 237         mutex_unlock(&adc->queue_mutex);
 238
 239         return 0;
 240 }
 241
 242 static struct platform_driver pcf50633_adc_driver = {
 243         .driver = {
 244                 .name = "pcf50633-adc",
 245         },
 246         .probe = pcf50633_adc_probe,
 247         .remove = pcf50633_adc_remove,
 248 };
 249
 250 module_platform_driver(pcf50633_adc_driver);
 251
 252 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
 253 MODULE_DESCRIPTION("PCF50633 adc driver");
 254 MODULE_LICENSE("GPL");
 255 MODULE_ALIAS("platform:pcf50633-adc");
 256