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linux
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 int result;
34 void (*callback)(struct pcf50633 *, void *, int);
35 void *callback_param;
36
37 /* Used in case of sync requests */
38 struct completion completion;
39
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
113pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param, int result)
114{
115 struct pcf50633_adc_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_request *req;
124 int err;
125
126 /* req is freed when the result is ready, in interrupt handler */
127 req = kzalloc(sizeof(*req), GFP_KERNEL);
128 if (!req)
129 return -ENOMEM;
130
131 req->mux = mux;
132 req->avg = avg;
133 req->callback = pcf50633_adc_sync_read_callback;
134 req->callback_param = req;
135
136 init_completion(&req->completion);
137 err = adc_enqueue_request(pcf, req);
138 if (err)
139 return err;
140
141 wait_for_completion(&req->completion);
142
143 /* FIXME by this time req might be already freed */
144 return req->result;
145}
146EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
147
148int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
149 void (*callback)(struct pcf50633 *, void *, int),
150 void *callback_param)
151{
152 struct pcf50633_adc_request *req;
153
154 /* req is freed when the result is ready, in interrupt handler */
155 req = kmalloc(sizeof(*req), GFP_KERNEL);
156 if (!req)
157 return -ENOMEM;
158
159 req->mux = mux;
160 req->avg = avg;
161 req->callback = callback;
162 req->callback_param = callback_param;
163
164 return adc_enqueue_request(pcf, req);
165}
166EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
167
168static int adc_result(struct pcf50633 *pcf)
169{
170 u8 adcs1, adcs3;
171 u16 result;
172
173 adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
174 adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
175 result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
176
177 dev_dbg(pcf->dev, "adc result = %d\n", result);
178
179 return result;
180}
181
182static void pcf50633_adc_irq(int irq, void *data)
183{
184 struct pcf50633_adc *adc = data;
185 struct pcf50633 *pcf = adc->pcf;
186 struct pcf50633_adc_request *req;
187 int head, res;
188
189 mutex_lock(&adc->queue_mutex);
190 head = adc->queue_head;
191
192 req = adc->queue[head];
193 if (WARN_ON(!req)) {
194 dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
195 mutex_unlock(&adc->queue_mutex);
196 return;
197 }
198 adc->queue[head] = NULL;
199 adc->queue_head = (head + 1) &
200 (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
201
202 res = adc_result(pcf);
203 trigger_next_adc_job_if_any(pcf);
204
205 mutex_unlock(&adc->queue_mutex);
206
207 req->callback(pcf, req->callback_param, res);
208 kfree(req);
209}
210
211static int __devinit pcf50633_adc_probe(struct platform_device *pdev)
212{
213 struct pcf50633_adc *adc;
214
215 adc = kzalloc(sizeof(*adc), GFP_KERNEL);
216 if (!adc)
217 return -ENOMEM;
218
219 adc->pcf = dev_to_pcf50633(pdev->dev.parent);
220 platform_set_drvdata(pdev, adc);
221
222 pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
223 pcf50633_adc_irq, adc);
224
225 mutex_init(&adc->queue_mutex);
226
227 return 0;
228}
229
230static int __devexit pcf50633_adc_remove(struct platform_device *pdev)
231{
232 struct pcf50633_adc *adc = platform_get_drvdata(pdev);
233 int i, head;
234
235 pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
236
237 mutex_lock(&adc->queue_mutex);
238 head = adc->queue_head;
239
240 if (WARN_ON(adc->queue[head]))
241 dev_err(adc->pcf->dev,
242 "adc driver removed with request pending\n");
243
244 for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
245 kfree(adc->queue[i]);
246
247 mutex_unlock(&adc->queue_mutex);
248 kfree(adc);
249
250 return 0;
251}
252
253static struct platform_driver pcf50633_adc_driver = {
254 .driver = {
255 .name = "pcf50633-adc",
256 },
257 .probe = pcf50633_adc_probe,
258 .remove = __devexit_p(pcf50633_adc_remove),
259};
260
261static int __init pcf50633_adc_init(void)
262{
263 return platform_driver_register(&pcf50633_adc_driver);
264}
265module_init(pcf50633_adc_init);
266
267static void __exit pcf50633_adc_exit(void)
268{
269 platform_driver_unregister(&pcf50633_adc_driver);
270}
271module_exit(pcf50633_adc_exit);
272
273MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
274MODULE_DESCRIPTION("PCF50633 adc driver");
275MODULE_LICENSE("GPL");
276MODULE_ALIAS("platform:pcf50633-adc");
277