Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa...
[linux-2.6-microblaze.git] / drivers / mfd / pcf50633-adc.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* NXP PCF50633 ADC Driver
3  *
4  * (C) 2006-2008 by Openmoko, Inc.
5  * Author: Balaji Rao <balajirrao@openmoko.org>
6  * All rights reserved.
7  *
8  * Broken down from monstrous PCF50633 driver mainly by
9  * Harald Welte, Andy Green and Werner Almesberger
10  *
11  *  NOTE: This driver does not yet support subtractive ADC mode, which means
12  *  you can do only one measurement per read request.
13  */
14
15 #include <linux/kernel.h>
16 #include <linux/slab.h>
17 #include <linux/module.h>
18 #include <linux/device.h>
19 #include <linux/platform_device.h>
20 #include <linux/completion.h>
21
22 #include <linux/mfd/pcf50633/core.h>
23 #include <linux/mfd/pcf50633/adc.h>
24
25 struct pcf50633_adc_request {
26         int mux;
27         int avg;
28         void (*callback)(struct pcf50633 *, void *, int);
29         void *callback_param;
30 };
31
32 struct pcf50633_adc_sync_request {
33         int result;
34         struct completion completion;
35 };
36
37 #define PCF50633_MAX_ADC_FIFO_DEPTH 8
38
39 struct pcf50633_adc {
40         struct pcf50633 *pcf;
41
42         /* Private stuff */
43         struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH];
44         int queue_head;
45         int queue_tail;
46         struct mutex queue_mutex;
47 };
48
49 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
50 {
51         return platform_get_drvdata(pcf->adc_pdev);
52 }
53
54 static void adc_setup(struct pcf50633 *pcf, int channel, int avg)
55 {
56         channel &= PCF50633_ADCC1_ADCMUX_MASK;
57
58         /* kill ratiometric, but enable ACCSW biasing */
59         pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00);
60         pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01);
61
62         /* start ADC conversion on selected channel */
63         pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg |
64                     PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT);
65 }
66
67 static void trigger_next_adc_job_if_any(struct pcf50633 *pcf)
68 {
69         struct pcf50633_adc *adc = __to_adc(pcf);
70         int head;
71
72         head = adc->queue_head;
73
74         if (!adc->queue[head])
75                 return;
76
77         adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg);
78 }
79
80 static int
81 adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req)
82 {
83         struct pcf50633_adc *adc = __to_adc(pcf);
84         int head, tail;
85
86         mutex_lock(&adc->queue_mutex);
87
88         head = adc->queue_head;
89         tail = adc->queue_tail;
90
91         if (adc->queue[tail]) {
92                 mutex_unlock(&adc->queue_mutex);
93                 dev_err(pcf->dev, "ADC queue is full, dropping request\n");
94                 return -EBUSY;
95         }
96
97         adc->queue[tail] = req;
98         if (head == tail)
99                 trigger_next_adc_job_if_any(pcf);
100         adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
101
102         mutex_unlock(&adc->queue_mutex);
103
104         return 0;
105 }
106
107 static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param,
108         int result)
109 {
110         struct pcf50633_adc_sync_request *req = param;
111
112         req->result = result;
113         complete(&req->completion);
114 }
115
116 int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg)
117 {
118         struct pcf50633_adc_sync_request req;
119         int ret;
120
121         init_completion(&req.completion);
122
123         ret = pcf50633_adc_async_read(pcf, mux, avg,
124                 pcf50633_adc_sync_read_callback, &req);
125         if (ret)
126                 return ret;
127
128         wait_for_completion(&req.completion);
129
130         return req.result;
131 }
132 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
133
134 int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
135                              void (*callback)(struct pcf50633 *, void *, int),
136                              void *callback_param)
137 {
138         struct pcf50633_adc_request *req;
139
140         /* req is freed when the result is ready, in interrupt handler */
141         req = kmalloc(sizeof(*req), GFP_KERNEL);
142         if (!req)
143                 return -ENOMEM;
144
145         req->mux = mux;
146         req->avg = avg;
147         req->callback = callback;
148         req->callback_param = callback_param;
149
150         return adc_enqueue_request(pcf, req);
151 }
152 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
153
154 static int adc_result(struct pcf50633 *pcf)
155 {
156         u8 adcs1, adcs3;
157         u16 result;
158
159         adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
160         adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
161         result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);
162
163         dev_dbg(pcf->dev, "adc result = %d\n", result);
164
165         return result;
166 }
167
168 static void pcf50633_adc_irq(int irq, void *data)
169 {
170         struct pcf50633_adc *adc = data;
171         struct pcf50633 *pcf = adc->pcf;
172         struct pcf50633_adc_request *req;
173         int head, res;
174
175         mutex_lock(&adc->queue_mutex);
176         head = adc->queue_head;
177
178         req = adc->queue[head];
179         if (WARN_ON(!req)) {
180                 dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
181                 mutex_unlock(&adc->queue_mutex);
182                 return;
183         }
184         adc->queue[head] = NULL;
185         adc->queue_head = (head + 1) &
186                                       (PCF50633_MAX_ADC_FIFO_DEPTH - 1);
187
188         res = adc_result(pcf);
189         trigger_next_adc_job_if_any(pcf);
190
191         mutex_unlock(&adc->queue_mutex);
192
193         req->callback(pcf, req->callback_param, res);
194         kfree(req);
195 }
196
197 static int pcf50633_adc_probe(struct platform_device *pdev)
198 {
199         struct pcf50633_adc *adc;
200
201         adc = devm_kzalloc(&pdev->dev, sizeof(*adc), GFP_KERNEL);
202         if (!adc)
203                 return -ENOMEM;
204
205         adc->pcf = dev_to_pcf50633(pdev->dev.parent);
206         platform_set_drvdata(pdev, adc);
207
208         pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
209                                         pcf50633_adc_irq, adc);
210
211         mutex_init(&adc->queue_mutex);
212
213         return 0;
214 }
215
216 static int pcf50633_adc_remove(struct platform_device *pdev)
217 {
218         struct pcf50633_adc *adc = platform_get_drvdata(pdev);
219         int i, head;
220
221         pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);
222
223         mutex_lock(&adc->queue_mutex);
224         head = adc->queue_head;
225
226         if (WARN_ON(adc->queue[head]))
227                 dev_err(adc->pcf->dev,
228                         "adc driver removed with request pending\n");
229
230         for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
231                 kfree(adc->queue[i]);
232
233         mutex_unlock(&adc->queue_mutex);
234
235         return 0;
236 }
237
238 static struct platform_driver pcf50633_adc_driver = {
239         .driver = {
240                 .name = "pcf50633-adc",
241         },
242         .probe = pcf50633_adc_probe,
243         .remove = pcf50633_adc_remove,
244 };
245
246 module_platform_driver(pcf50633_adc_driver);
247
248 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
249 MODULE_DESCRIPTION("PCF50633 adc driver");
250 MODULE_LICENSE("GPL");
251 MODULE_ALIAS("platform:pcf50633-adc");
252