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
29struct pcf50633_adc_request {
30 int mux;
31 int avg;
32 void (*callback)(struct pcf50633 *, void *, int);
33 void *callback_param;
34};
35
36struct pcf50633_adc_sync_request {
37 int result;
38 struct completion completion;
39};
40
41#define PCF50633_MAX_ADC_FIFO_DEPTH 8
42
43struct 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
53static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
54{
55 return platform_get_drvdata(pcf->adc_pdev);
56}
57
58static 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
71static 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
84static int
85adc_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
111static 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
120int 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}
136EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
137
138int 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}
156EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
157
158static 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
172static 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
201static 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
220static 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
242static 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
250module_platform_driver(pcf50633_adc_driver);
251
252MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
253MODULE_DESCRIPTION("PCF50633 adc driver");
254MODULE_LICENSE("GPL");
255MODULE_ALIAS("platform:pcf50633-adc");
256
257