summaryrefslogtreecommitdiffstats
path: root/drivers/mfd/pcf50633-adc.c
blob: 18b53cb72feae4984b44b6cea94c2f6d68fc3e40 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/* NXP PCF50633 ADC Driver
 *
 * (C) 2006-2008 by Openmoko, Inc.
 * Author: Balaji Rao <balajirrao@openmoko.org>
 * All rights reserved.
 *
 * Broken down from monstrous PCF50633 driver mainly by
 * Harald Welte, Andy Green and Werner Almesberger
 *
 *  This program is free software; you can redistribute  it and/or modify it
 *  under  the terms of  the GNU General  Public License as published by the
 *  Free Software Foundation;  either version 2 of the  License, or (at your
 *  option) any later version.
 *
 *  NOTE: This driver does not yet support subtractive ADC mode, which means
 *  you can do only one measurement per read request.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/completion.h>

#include <linux/mfd/pcf50633/core.h>
#include <linux/mfd/pcf50633/adc.h>

struct pcf50633_adc_request {
	int mux;
	int avg;
	void (*callback)(struct pcf50633 *, void *, int);
	void *callback_param;
};

struct pcf50633_adc_sync_request {
	int result;
	struct completion completion;
};

#define PCF50633_MAX_ADC_FIFO_DEPTH 8

struct pcf50633_adc {
	struct pcf50633 *pcf;

	/* Private stuff */
	struct pcf50633_adc_request *queue[PCF50633_MAX_ADC_FIFO_DEPTH];
	int queue_head;
	int queue_tail;
	struct mutex queue_mutex;
};

static inline struct pcf50633_adc *__to_adc(struct pcf50633 *pcf)
{
	return platform_get_drvdata(pcf->adc_pdev);
}

static void adc_setup(struct pcf50633 *pcf, int channel, int avg)
{
	channel &= PCF50633_ADCC1_ADCMUX_MASK;

	/* kill ratiometric, but enable ACCSW biasing */
	pcf50633_reg_write(pcf, PCF50633_REG_ADCC2, 0x00);
	pcf50633_reg_write(pcf, PCF50633_REG_ADCC3, 0x01);

	/* start ADC conversion on selected channel */
	pcf50633_reg_write(pcf, PCF50633_REG_ADCC1, channel | avg |
		    PCF50633_ADCC1_ADCSTART | PCF50633_ADCC1_RES_10BIT);
}

static void trigger_next_adc_job_if_any(struct pcf50633 *pcf)
{
	struct pcf50633_adc *adc = __to_adc(pcf);
	int head;

	head = adc->queue_head;

	if (!adc->queue[head])
		return;

	adc_setup(pcf, adc->queue[head]->mux, adc->queue[head]->avg);
}

static int
adc_enqueue_request(struct pcf50633 *pcf, struct pcf50633_adc_request *req)
{
	struct pcf50633_adc *adc = __to_adc(pcf);
	int head, tail;

	mutex_lock(&adc->queue_mutex);

	head = adc->queue_head;
	tail = adc->queue_tail;

	if (adc->queue[tail]) {
		mutex_unlock(&adc->queue_mutex);
		dev_err(pcf->dev, "ADC queue is full, dropping request\n");
		return -EBUSY;
	}

	adc->queue[tail] = req;
	if (head == tail)
		trigger_next_adc_job_if_any(pcf);
	adc->queue_tail = (tail + 1) & (PCF50633_MAX_ADC_FIFO_DEPTH - 1);

	mutex_unlock(&adc->queue_mutex);

	return 0;
}

static void pcf50633_adc_sync_read_callback(struct pcf50633 *pcf, void *param,
	int result)
{
	struct pcf50633_adc_sync_request *req = param;

	req->result = result;
	complete(&req->completion);
}

int pcf50633_adc_sync_read(struct pcf50633 *pcf, int mux, int avg)
{
	struct pcf50633_adc_sync_request req;
	int ret;

	init_completion(&req.completion);

	ret = pcf50633_adc_async_read(pcf, mux, avg,
		pcf50633_adc_sync_read_callback, &req);
	if (ret)
		return ret;

	wait_for_completion(&req.completion);

	return req.result;
}
EXPORT_SYMBOL_GPL(pcf50633_adc_sync_read);

int pcf50633_adc_async_read(struct pcf50633 *pcf, int mux, int avg,
			     void (*callback)(struct pcf50633 *, void *, int),
			     void *callback_param)
{
	struct pcf50633_adc_request *req;

	/* req is freed when the result is ready, in interrupt handler */
	req = kmalloc(sizeof(*req), GFP_KERNEL);
	if (!req)
		return -ENOMEM;

	req->mux = mux;
	req->avg = avg;
	req->callback = callback;
	req->callback_param = callback_param;

	return adc_enqueue_request(pcf, req);
}
EXPORT_SYMBOL_GPL(pcf50633_adc_async_read);

static int adc_result(struct pcf50633 *pcf)
{
	u8 adcs1, adcs3;
	u16 result;

	adcs1 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS1);
	adcs3 = pcf50633_reg_read(pcf, PCF50633_REG_ADCS3);
	result = (adcs1 << 2) | (adcs3 & PCF50633_ADCS3_ADCDAT1L_MASK);

	dev_dbg(pcf->dev, "adc result = %d\n", result);

	return result;
}

static void pcf50633_adc_irq(int irq, void *data)
{
	struct pcf50633_adc *adc = data;
	struct pcf50633 *pcf = adc->pcf;
	struct pcf50633_adc_request *req;
	int head, res;

	mutex_lock(&adc->queue_mutex);
	head = adc->queue_head;

	req = adc->queue[head];
	if (WARN_ON(!req)) {
		dev_err(pcf->dev, "pcf50633-adc irq: ADC queue empty!\n");
		mutex_unlock(&adc->queue_mutex);
		return;
	}
	adc->queue[head] = NULL;
	adc->queue_head = (head + 1) &
				      (PCF50633_MAX_ADC_FIFO_DEPTH - 1);

	res = adc_result(pcf);
	trigger_next_adc_job_if_any(pcf);

	mutex_unlock(&adc->queue_mutex);

	req->callback(pcf, req->callback_param, res);
	kfree(req);
}

static int pcf50633_adc_probe(struct platform_device *pdev)
{
	struct pcf50633_adc *adc;

	adc = kzalloc(sizeof(*adc), GFP_KERNEL);
	if (!adc)
		return -ENOMEM;

	adc->pcf = dev_to_pcf50633(pdev->dev.parent);
	platform_set_drvdata(pdev, adc);

	pcf50633_register_irq(adc->pcf, PCF50633_IRQ_ADCRDY,
					pcf50633_adc_irq, adc);

	mutex_init(&adc->queue_mutex);

	return 0;
}

static int pcf50633_adc_remove(struct platform_device *pdev)
{
	struct pcf50633_adc *adc = platform_get_drvdata(pdev);
	int i, head;

	pcf50633_free_irq(adc->pcf, PCF50633_IRQ_ADCRDY);

	mutex_lock(&adc->queue_mutex);
	head = adc->queue_head;

	if (WARN_ON(adc->queue[head]))
		dev_err(adc->pcf->dev,
			"adc driver removed with request pending\n");

	for (i = 0; i < PCF50633_MAX_ADC_FIFO_DEPTH; i++)
		kfree(adc->queue[i]);

	mutex_unlock(&adc->queue_mutex);
	kfree(adc);

	return 0;
}

static struct platform_driver pcf50633_adc_driver = {
	.driver = {
		.name = "pcf50633-adc",
	},
	.probe = pcf50633_adc_probe,
	.remove = pcf50633_adc_remove,
};

module_platform_driver(pcf50633_adc_driver);

MODULE_AUTHOR("Balaji Rao <balajirrao@openmoko.org>");
MODULE_DESCRIPTION("PCF50633 adc driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pcf50633-adc");