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