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
__to_adc(struct pcf50633 * pcf)49 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
50 {
51 return platform_get_drvdata(pcf->adc_pdev);
52 }
53
adc_setup(struct pcf50633 * pcf,int channel,int avg)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
trigger_next_adc_job_if_any(struct pcf50633 * pcf)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
adc_enqueue_request(struct pcf50633 * pcf,struct pcf50633_adc_request * req)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
pcf50633_adc_sync_read_callback(struct pcf50633 * pcf,void * param,int result)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
pcf50633_adc_sync_read(struct pcf50633 * pcf,int mux,int avg)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
pcf50633_adc_async_read(struct pcf50633 * pcf,int mux,int avg,void (* callback)(struct pcf50633 *,void *,int),void * callback_param)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 int ret;
140
141 /* req is freed when the result is ready, in interrupt handler */
142 req = kmalloc(sizeof(*req), GFP_KERNEL);
143 if (!req)
144 return -ENOMEM;
145
146 req->mux = mux;
147 req->avg = avg;
148 req->callback = callback;
149 req->callback_param = callback_param;
150
151 ret = adc_enqueue_request(pcf, req);
152 if (ret)
153 kfree(req);
154
155 return ret;
156 }
157 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
158
adc_result(struct pcf50633 * pcf)159 static 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
pcf50633_adc_irq(int irq,void * data)173 static 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
pcf50633_adc_probe(struct platform_device * pdev)202 static 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
pcf50633_adc_remove(struct platform_device * pdev)221 static 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
243 static 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
251 module_platform_driver(pcf50633_adc_driver);
252
253 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
254 MODULE_DESCRIPTION("PCF50633 adc driver");
255 MODULE_LICENSE("GPL");
256 MODULE_ALIAS("platform:pcf50633-adc");
257
258