summaryrefslogtreecommitdiffstats
path: root/drivers/iio/adc/ti_am335x_adc.c
blob: cd030e100c395416e4043ad6659f7030266b9b7e (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
259
260
/*
 * TI ADC MFD driver
 *
 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
 *
 * 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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/iio/iio.h>

#include <linux/mfd/ti_am335x_tscadc.h>
#include <linux/platform_data/ti_am335x_adc.h>

struct tiadc_device {
	struct ti_tscadc_dev *mfd_tscadc;
	int channels;
};

static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
{
	return readl(adc->mfd_tscadc->tscadc_base + reg);
}

static void tiadc_writel(struct tiadc_device *adc, unsigned int reg,
					unsigned int val)
{
	writel(val, adc->mfd_tscadc->tscadc_base + reg);
}

static void tiadc_step_config(struct tiadc_device *adc_dev)
{
	unsigned int stepconfig;
	int i, channels = 0, steps;

	/*
	 * There are 16 configurable steps and 8 analog input
	 * lines available which are shared between Touchscreen and ADC.
	 *
	 * Steps backwards i.e. from 16 towards 0 are used by ADC
	 * depending on number of input lines needed.
	 * Channel would represent which analog input
	 * needs to be given to ADC to digitalize data.
	 */

	steps = TOTAL_STEPS - adc_dev->channels;
	channels = TOTAL_CHANNELS - adc_dev->channels;

	stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;

	for (i = (steps + 1); i <= TOTAL_STEPS; i++) {
		tiadc_writel(adc_dev, REG_STEPCONFIG(i),
				stepconfig | STEPCONFIG_INP(channels));
		tiadc_writel(adc_dev, REG_STEPDELAY(i),
				STEPCONFIG_OPENDLY);
		channels++;
	}
	tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB);
}

static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
{
	struct iio_chan_spec *chan_array;
	int i;

	indio_dev->num_channels = channels;
	chan_array = kcalloc(indio_dev->num_channels,
			sizeof(struct iio_chan_spec), GFP_KERNEL);

	if (chan_array == NULL)
		return -ENOMEM;

	for (i = 0; i < (indio_dev->num_channels); i++) {
		struct iio_chan_spec *chan = chan_array + i;
		chan->type = IIO_VOLTAGE;
		chan->indexed = 1;
		chan->channel = i;
		chan->info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT;
	}

	indio_dev->channels = chan_array;

	return indio_dev->num_channels;
}

static void tiadc_channels_remove(struct iio_dev *indio_dev)
{
	kfree(indio_dev->channels);
}

static int tiadc_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int *val, int *val2, long mask)
{
	struct tiadc_device *adc_dev = iio_priv(indio_dev);
	int i;
	unsigned int fifo1count, readx1;

	/*
	 * When the sub-system is first enabled,
	 * the sequencer will always start with the
	 * lowest step (1) and continue until step (16).
	 * For ex: If we have enabled 4 ADC channels and
	 * currently use only 1 out of them, the
	 * sequencer still configures all the 4 steps,
	 * leading to 3 unwanted data.
	 * Hence we need to flush out this data.
	 */

	fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
	for (i = 0; i < fifo1count; i++) {
		readx1 = tiadc_readl(adc_dev, REG_FIFO1);
		if (i == chan->channel)
			*val = readx1 & 0xfff;
	}
	tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB);

	return IIO_VAL_INT;
}

static const struct iio_info tiadc_info = {
	.read_raw = &tiadc_read_raw,
};

static int tiadc_probe(struct platform_device *pdev)
{
	struct iio_dev		*indio_dev;
	struct tiadc_device	*adc_dev;
	struct ti_tscadc_dev	*tscadc_dev = pdev->dev.platform_data;
	struct mfd_tscadc_board	*pdata;
	int			err;

	pdata = tscadc_dev->dev->platform_data;
	if (!pdata || !pdata->adc_init) {
		dev_err(&pdev->dev, "Could not find platform data\n");
		return -EINVAL;
	}

	indio_dev = iio_device_alloc(sizeof(struct tiadc_device));
	if (indio_dev == NULL) {
		dev_err(&pdev->dev, "failed to allocate iio device\n");
		err = -ENOMEM;
		goto err_ret;
	}
	adc_dev = iio_priv(indio_dev);

	adc_dev->mfd_tscadc = tscadc_dev;
	adc_dev->channels = pdata->adc_init->adc_channels;

	indio_dev->dev.parent = &pdev->dev;
	indio_dev->name = dev_name(&pdev->dev);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &tiadc_info;

	tiadc_step_config(adc_dev);

	err = tiadc_channel_init(indio_dev, adc_dev->channels);
	if (err < 0)
		goto err_free_device;

	err = iio_device_register(indio_dev);
	if (err)
		goto err_free_channels;

	platform_set_drvdata(pdev, indio_dev);

	return 0;

err_free_channels:
	tiadc_channels_remove(indio_dev);
err_free_device:
	iio_device_free(indio_dev);
err_ret:
	return err;
}

static int tiadc_remove(struct platform_device *pdev)
{
	struct iio_dev *indio_dev = platform_get_drvdata(pdev);

	iio_device_unregister(indio_dev);
	tiadc_channels_remove(indio_dev);

	iio_device_free(indio_dev);

	return 0;
}

#ifdef CONFIG_PM
static int tiadc_suspend(struct device *dev)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct tiadc_device *adc_dev = iio_priv(indio_dev);
	struct ti_tscadc_dev *tscadc_dev = dev->platform_data;
	unsigned int idle;

	if (!device_may_wakeup(tscadc_dev->dev)) {
		idle = tiadc_readl(adc_dev, REG_CTRL);
		idle &= ~(CNTRLREG_TSCSSENB);
		tiadc_writel(adc_dev, REG_CTRL, (idle |
				CNTRLREG_POWERDOWN));
	}

	return 0;
}

static int tiadc_resume(struct device *dev)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct tiadc_device *adc_dev = iio_priv(indio_dev);
	unsigned int restore;

	/* Make sure ADC is powered up */
	restore = tiadc_readl(adc_dev, REG_CTRL);
	restore &= ~(CNTRLREG_POWERDOWN);
	tiadc_writel(adc_dev, REG_CTRL, restore);

	tiadc_step_config(adc_dev);

	return 0;
}

static const struct dev_pm_ops tiadc_pm_ops = {
	.suspend = tiadc_suspend,
	.resume = tiadc_resume,
};
#define TIADC_PM_OPS (&tiadc_pm_ops)
#else
#define TIADC_PM_OPS NULL
#endif

static struct platform_driver tiadc_driver = {
	.driver = {
		.name   = "tiadc",
		.owner	= THIS_MODULE,
		.pm	= TIADC_PM_OPS,
	},
	.probe	= tiadc_probe,
	.remove	= tiadc_remove,
};

module_platform_driver(tiadc_driver);

MODULE_DESCRIPTION("TI ADC controller driver");
MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
MODULE_LICENSE("GPL");