xref: /openbmc/linux/drivers/mfd/pcf50633-adc.c (revision 8b450dcf)
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