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/drivers/mfd/pcf50633-adc.c

http://github.com/mirrors/linux
C | 252 lines | 175 code | 60 blank | 17 comment | 10 complexity | 1ad6676e667f763433c553f300d278a0 MD5 | raw file
  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
 25struct pcf50633_adc_request {
 26	int mux;
 27	int avg;
 28	void (*callback)(struct pcf50633 *, void *, int);
 29	void *callback_param;
 30};
 31
 32struct pcf50633_adc_sync_request {
 33	int result;
 34	struct completion completion;
 35};
 36
 37#define PCF50633_MAX_ADC_FIFO_DEPTH 8
 38
 39struct 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
 49static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
 50{
 51	return platform_get_drvdata(pcf->adc_pdev);
 52}
 53
 54static 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
 67static 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
 80static int
 81adc_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
107static 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
116int 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}
132EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);
133
134int 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}
152EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);
153
154static 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
168static 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
197static 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
216static 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
238static 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
246module_platform_driver(pcf50633_adc_driver);
247
248MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
249MODULE_DESCRIPTION("PCF50633 adc driver");
250MODULE_LICENSE("GPL");
251MODULE_ALIAS("platform:pcf50633-adc");
252