1 /*
2 * lpc32xx_adc.c - Support for ADC in LPC32XX
3 *
4 * 3-channel, 10-bit ADC
5 *
6 * Copyright (C) 2011, 2012 Roland Stigge <stigge@antcom.de>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23 #include <linux/module.h>
24 #include <linux/platform_device.h>
25 #include <linux/interrupt.h>
26 #include <linux/device.h>
27 #include <linux/kernel.h>
28 #include <linux/slab.h>
29 #include <linux/io.h>
30 #include <linux/clk.h>
31 #include <linux/err.h>
32 #include <linux/completion.h>
33
34 #include "../iio.h"
35 #include "../sysfs.h"
36
37 /*
38 * LPC32XX registers definitions
39 */
40 #define LPC32XX_ADC_SELECT(x) ((x) + 0x04)
41 #define LPC32XX_ADC_CTRL(x) ((x) + 0x08)
42 #define LPC32XX_ADC_VALUE(x) ((x) + 0x48)
43
44 /* Bit definitions for LPC32XX_ADC_SELECT: */
45 #define AD_REFm 0x00000200 /* constant, always write this value! */
46 #define AD_REFp 0x00000080 /* constant, always write this value! */
47 #define AD_IN 0x00000010 /* multiple of this is the */
48 /* channel number: 0, 1, 2 */
49 #define AD_INTERNAL 0x00000004 /* constant, always write this value! */
50
51 /* Bit definitions for LPC32XX_ADC_CTRL: */
52 #define AD_STROBE 0x00000002
53 #define AD_PDN_CTRL 0x00000004
54
55 /* Bit definitions for LPC32XX_ADC_VALUE: */
56 #define ADC_VALUE_MASK 0x000003FF
57
58 #define MOD_NAME "lpc32xx-adc"
59
60 struct lpc32xx_adc_info {
61 void __iomem *adc_base;
62 struct clk *clk;
63 struct completion completion;
64
65 u32 value;
66 };
67
lpc32xx_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)68 static int lpc32xx_read_raw(struct iio_dev *indio_dev,
69 struct iio_chan_spec const *chan,
70 int *val,
71 int *val2,
72 long mask)
73 {
74 struct lpc32xx_adc_info *info = iio_priv(indio_dev);
75
76 if (mask == 0) {
77 mutex_lock(&indio_dev->mlock);
78 clk_enable(info->clk);
79 /* Measurement setup */
80 __raw_writel(AD_INTERNAL | (chan->address) | AD_REFp | AD_REFm,
81 LPC32XX_ADC_SELECT(info->adc_base));
82 /* Trigger conversion */
83 __raw_writel(AD_PDN_CTRL | AD_STROBE,
84 LPC32XX_ADC_CTRL(info->adc_base));
85 wait_for_completion(&info->completion); /* set by ISR */
86 clk_disable(info->clk);
87 *val = info->value;
88 mutex_unlock(&indio_dev->mlock);
89
90 return IIO_VAL_INT;
91 }
92
93 return -EINVAL;
94 }
95
96 static const struct iio_info lpc32xx_adc_iio_info = {
97 .read_raw = &lpc32xx_read_raw,
98 .driver_module = THIS_MODULE,
99 };
100
101 #define LPC32XX_ADC_CHANNEL(_index) { \
102 .type = IIO_VOLTAGE, \
103 .indexed = 1, \
104 .channel = _index, \
105 .address = AD_IN * _index, \
106 .scan_index = _index, \
107 }
108
109 static struct iio_chan_spec lpc32xx_adc_iio_channels[] = {
110 LPC32XX_ADC_CHANNEL(0),
111 LPC32XX_ADC_CHANNEL(1),
112 LPC32XX_ADC_CHANNEL(2),
113 };
114
lpc32xx_adc_isr(int irq,void * dev_id)115 static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id)
116 {
117 struct lpc32xx_adc_info *info = (struct lpc32xx_adc_info *) dev_id;
118
119 /* Read value and clear irq */
120 info->value = __raw_readl(LPC32XX_ADC_VALUE(info->adc_base)) &
121 ADC_VALUE_MASK;
122 complete(&info->completion);
123
124 return IRQ_HANDLED;
125 }
126
lpc32xx_adc_probe(struct platform_device * pdev)127 static int __devinit lpc32xx_adc_probe(struct platform_device *pdev)
128 {
129 struct lpc32xx_adc_info *info = NULL;
130 struct resource *res;
131 int retval = -ENODEV;
132 struct iio_dev *iodev = NULL;
133 int irq;
134
135 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
136 if (!res) {
137 dev_err(&pdev->dev, "failed to get platform I/O memory\n");
138 retval = -EBUSY;
139 goto errout1;
140 }
141
142 iodev = iio_allocate_device(sizeof(struct lpc32xx_adc_info));
143 if (!iodev) {
144 dev_err(&pdev->dev, "failed allocating iio device\n");
145 retval = -ENOMEM;
146 goto errout1;
147 }
148
149 info = iio_priv(iodev);
150
151 info->adc_base = ioremap(res->start, res->end - res->start + 1);
152 if (!info->adc_base) {
153 dev_err(&pdev->dev, "failed mapping memory\n");
154 retval = -EBUSY;
155 goto errout2;
156 }
157
158 info->clk = clk_get(&pdev->dev, NULL);
159 if (IS_ERR(info->clk)) {
160 dev_err(&pdev->dev, "failed getting clock\n");
161 goto errout3;
162 }
163
164 irq = platform_get_irq(pdev, 0);
165 if ((irq < 0) || (irq >= NR_IRQS)) {
166 dev_err(&pdev->dev, "failed getting interrupt resource\n");
167 retval = -EINVAL;
168 goto errout4;
169 }
170
171 retval = request_irq(irq, lpc32xx_adc_isr, 0, MOD_NAME, info);
172 if (retval < 0) {
173 dev_err(&pdev->dev, "failed requesting interrupt\n");
174 goto errout4;
175 }
176
177 platform_set_drvdata(pdev, iodev);
178
179 init_completion(&info->completion);
180
181 iodev->name = MOD_NAME;
182 iodev->dev.parent = &pdev->dev;
183 iodev->info = &lpc32xx_adc_iio_info;
184 iodev->modes = INDIO_DIRECT_MODE;
185 iodev->channels = lpc32xx_adc_iio_channels;
186 iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels);
187
188 retval = iio_device_register(iodev);
189 if (retval)
190 goto errout5;
191
192 dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq);
193
194 return 0;
195
196 errout5:
197 free_irq(irq, iodev);
198 errout4:
199 clk_put(info->clk);
200 errout3:
201 iounmap(info->adc_base);
202 errout2:
203 iio_free_device(iodev);
204 errout1:
205 return retval;
206 }
207
lpc32xx_adc_remove(struct platform_device * pdev)208 static int __devexit lpc32xx_adc_remove(struct platform_device *pdev)
209 {
210 struct iio_dev *iodev = platform_get_drvdata(pdev);
211 struct lpc32xx_adc_info *info = iio_priv(iodev);
212 int irq = platform_get_irq(pdev, 0);
213
214 iio_device_unregister(iodev);
215 free_irq(irq, iodev);
216 platform_set_drvdata(pdev, NULL);
217 clk_put(info->clk);
218 iounmap(info->adc_base);
219 iio_free_device(iodev);
220
221 return 0;
222 }
223
224 static struct platform_driver lpc32xx_adc_driver = {
225 .probe = lpc32xx_adc_probe,
226 .remove = __devexit_p(lpc32xx_adc_remove),
227 .driver = {
228 .name = MOD_NAME,
229 .owner = THIS_MODULE,
230 },
231 };
232
233 module_platform_driver(lpc32xx_adc_driver);
234
235 MODULE_AUTHOR("Roland Stigge <stigge@antcom.de>");
236 MODULE_DESCRIPTION("LPC32XX ADC driver");
237 MODULE_LICENSE("GPL");
238