linux/drivers/mfd/pcf50633-adc.c
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   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
  30struct pcf50633_adc_request {
  31        int mux;
  32        int avg;
  33        void (*callback)(struct pcf50633 *, void *, int);
  34        void *callback_param;
  35};
  36
  37struct pcf50633_adc_sync_request {
  38        int result;
  39        struct completion completion;
  40};
  41
  42#define PCF50633_MAX_ADC_FIFO_DEPTH 8
  43
  44struct 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
  54static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
  55{
  56        return platform_get_drvdata(pcf->adc_pdev);
  57}
  58
  59static 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
  72static 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
  85static int
  86adc_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
 112static 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
 121int 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}
 137EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
 138
 139int 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}
 157EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
 158
 159static 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
 173static 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
 202static int pcf50633_adc_probe(struct platform_device *pdev)
 203{
 204        struct pcf50633_adc *adc;
 205
 206        adc = devm_kzalloc(&pdev->dev, 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
 221static 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
 240        return 0;
 241}
 242
 243static struct platform_driver pcf50633_adc_driver = {
 244        .driver = {
 245                .name = "pcf50633-adc",
 246        },
 247        .probe = pcf50633_adc_probe,
 248        .remove = pcf50633_adc_remove,
 249};
 250
 251module_platform_driver(pcf50633_adc_driver);
 252
 253MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
 254MODULE_DESCRIPTION("PCF50633 adc driver");
 255MODULE_LICENSE("GPL");
 256MODULE_ALIAS("platform:pcf50633-adc");
 257
 258
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