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Linux/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 
257 

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