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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 
29 struct pcf50633_adc_request {
30 	int mux;
31 	int avg;
32 	void (*callback)(struct pcf50633 *, void *, int);
33 	void *callback_param;
34 };
35 
36 struct pcf50633_adc_sync_request {
37 	int result;
38 	struct completion completion;
39 };
40 
41 #define PCF50633_MAX_ADC_FIFO_DEPTH 8
42 
43 struct 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 
__to_adc(struct pcf50633 * pcf)53 static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
54 {
55 	return platform_get_drvdata(pcf->adc_pdev);
56 }
57 
adc_setup(struct pcf50633 * pcf,int channel,int avg)58 static 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 
trigger_next_adc_job_if_any(struct pcf50633 * pcf)71 static 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 
84 static int
adc_enqueue_request(struct pcf50633 * pcf,struct pcf50633_adc_request * req)85 adc_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 
pcf50633_adc_sync_read_callback(struct pcf50633 * pcf,void * param,int result)111 static 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 
pcf50633_adc_sync_read(struct pcf50633 * pcf,int mux,int avg)120 int 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 }
136 EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
137 
pcf50633_adc_async_read(struct pcf50633 * pcf,int mux,int avg,void (* callback)(struct pcf50633 *,void *,int),void * callback_param)138 int 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 }
156 EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
157 
adc_result(struct pcf50633 * pcf)158 static 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 
pcf50633_adc_irq(int irq,void * data)172 static 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 
pcf50633_adc_probe(struct platform_device * pdev)201 static 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 
pcf50633_adc_remove(struct platform_device * pdev)220 static 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 
242 static 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 
250 module_platform_driver(pcf50633_adc_driver);
251 
252 MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
253 MODULE_DESCRIPTION("PCF50633 adc driver");
254 MODULE_LICENSE("GPL");
255 MODULE_ALIAS("platform:pcf50633-adc");
256 
257