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
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
|
/*
* ST SPEAr ADC driver
*
* Copyright 2012 Stefan Roese <sr@denx.de>
*
* Licensed under the GPL-2.
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/completion.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/* SPEAR registers definitions */
#define SPEAR600_ADC_SCAN_RATE_LO(x) ((x) & 0xFFFF)
#define SPEAR600_ADC_SCAN_RATE_HI(x) (((x) >> 0x10) & 0xFFFF)
#define SPEAR_ADC_CLK_LOW(x) (((x) & 0xf) << 0)
#define SPEAR_ADC_CLK_HIGH(x) (((x) & 0xf) << 4)
/* Bit definitions for SPEAR_ADC_STATUS */
#define SPEAR_ADC_STATUS_START_CONVERSION BIT(0)
#define SPEAR_ADC_STATUS_CHANNEL_NUM(x) ((x) << 1)
#define SPEAR_ADC_STATUS_ADC_ENABLE BIT(4)
#define SPEAR_ADC_STATUS_AVG_SAMPLE(x) ((x) << 5)
#define SPEAR_ADC_STATUS_VREF_INTERNAL BIT(9)
#define SPEAR_ADC_DATA_MASK 0x03ff
#define SPEAR_ADC_DATA_BITS 10
#define SPEAR_ADC_MOD_NAME "spear-adc"
#define SPEAR_ADC_CHANNEL_NUM 8
#define SPEAR_ADC_CLK_MIN 2500000
#define SPEAR_ADC_CLK_MAX 20000000
struct adc_regs_spear3xx {
u32 status;
u32 average;
u32 scan_rate;
u32 clk; /* Not avail for 1340 & 1310 */
u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
u32 ch_data[SPEAR_ADC_CHANNEL_NUM];
};
struct chan_data {
u32 lsb;
u32 msb;
};
struct adc_regs_spear6xx {
u32 status;
u32 pad[2];
u32 clk;
u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM];
struct chan_data ch_data[SPEAR_ADC_CHANNEL_NUM];
u32 scan_rate_lo;
u32 scan_rate_hi;
struct chan_data average;
};
struct spear_adc_state {
struct device_node *np;
struct adc_regs_spear3xx __iomem *adc_base_spear3xx;
struct adc_regs_spear6xx __iomem *adc_base_spear6xx;
struct clk *clk;
struct completion completion;
u32 current_clk;
u32 sampling_freq;
u32 avg_samples;
u32 vref_external;
u32 value;
};
/*
* Functions to access some SPEAr ADC register. Abstracted into
* static inline functions, because of different register offsets
* on different SoC variants (SPEAr300 vs SPEAr600 etc).
*/
static void spear_adc_set_status(struct spear_adc_state *st, u32 val)
{
__raw_writel(val, &st->adc_base_spear6xx->status);
}
static void spear_adc_set_clk(struct spear_adc_state *st, u32 val)
{
u32 clk_high, clk_low, count;
u32 apb_clk = clk_get_rate(st->clk);
count = DIV_ROUND_UP(apb_clk, val);
clk_low = count / 2;
clk_high = count - clk_low;
st->current_clk = apb_clk / count;
__raw_writel(SPEAR_ADC_CLK_LOW(clk_low) | SPEAR_ADC_CLK_HIGH(clk_high),
&st->adc_base_spear6xx->clk);
}
static void spear_adc_set_ctrl(struct spear_adc_state *st, int n,
u32 val)
{
__raw_writel(val, &st->adc_base_spear6xx->ch_ctrl[n]);
}
static u32 spear_adc_get_average(struct spear_adc_state *st)
{
if (of_device_is_compatible(st->np, "st,spear600-adc")) {
return __raw_readl(&st->adc_base_spear6xx->average.msb) &
SPEAR_ADC_DATA_MASK;
} else {
return __raw_readl(&st->adc_base_spear3xx->average) &
SPEAR_ADC_DATA_MASK;
}
}
static void spear_adc_set_scanrate(struct spear_adc_state *st, u32 rate)
{
if (of_device_is_compatible(st->np, "st,spear600-adc")) {
__raw_writel(SPEAR600_ADC_SCAN_RATE_LO(rate),
&st->adc_base_spear6xx->scan_rate_lo);
__raw_writel(SPEAR600_ADC_SCAN_RATE_HI(rate),
&st->adc_base_spear6xx->scan_rate_hi);
} else {
__raw_writel(rate, &st->adc_base_spear3xx->scan_rate);
}
}
static int spear_adc_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val,
int *val2,
long mask)
{
struct spear_adc_state *st = iio_priv(indio_dev);
u32 status;
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&indio_dev->mlock);
status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) |
SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) |
SPEAR_ADC_STATUS_START_CONVERSION |
SPEAR_ADC_STATUS_ADC_ENABLE;
if (st->vref_external == 0)
status |= SPEAR_ADC_STATUS_VREF_INTERNAL;
spear_adc_set_status(st, status);
wait_for_completion(&st->completion); /* set by ISR */
*val = st->value;
mutex_unlock(&indio_dev->mlock);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = st->vref_external;
*val2 = SPEAR_ADC_DATA_BITS;
return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_SAMP_FREQ:
*val = st->current_clk;
return IIO_VAL_INT;
}
return -EINVAL;
}
static int spear_adc_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val,
int val2,
long mask)
{
struct spear_adc_state *st = iio_priv(indio_dev);
int ret = 0;
if (mask != IIO_CHAN_INFO_SAMP_FREQ)
return -EINVAL;
mutex_lock(&indio_dev->mlock);
if ((val < SPEAR_ADC_CLK_MIN) ||
(val > SPEAR_ADC_CLK_MAX) ||
(val2 != 0)) {
ret = -EINVAL;
goto out;
}
spear_adc_set_clk(st, val);
out:
mutex_unlock(&indio_dev->mlock);
return ret;
}
#define SPEAR_ADC_CHAN(idx) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
.channel = idx, \
}
static const struct iio_chan_spec spear_adc_iio_channels[] = {
SPEAR_ADC_CHAN(0),
SPEAR_ADC_CHAN(1),
SPEAR_ADC_CHAN(2),
SPEAR_ADC_CHAN(3),
SPEAR_ADC_CHAN(4),
SPEAR_ADC_CHAN(5),
SPEAR_ADC_CHAN(6),
SPEAR_ADC_CHAN(7),
};
static irqreturn_t spear_adc_isr(int irq, void *dev_id)
{
struct spear_adc_state *st = dev_id;
/* Read value to clear IRQ */
st->value = spear_adc_get_average(st);
complete(&st->completion);
return IRQ_HANDLED;
}
static int spear_adc_configure(struct spear_adc_state *st)
{
int i;
/* Reset ADC core */
spear_adc_set_status(st, 0);
__raw_writel(0, &st->adc_base_spear6xx->clk);
for (i = 0; i < 8; i++)
spear_adc_set_ctrl(st, i, 0);
spear_adc_set_scanrate(st, 0);
spear_adc_set_clk(st, st->sampling_freq);
return 0;
}
static const struct iio_info spear_adc_info = {
.read_raw = &spear_adc_read_raw,
.write_raw = &spear_adc_write_raw,
.driver_module = THIS_MODULE,
};
static int spear_adc_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct device *dev = &pdev->dev;
struct spear_adc_state *st;
struct iio_dev *indio_dev = NULL;
int ret = -ENODEV;
int irq;
indio_dev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_state));
if (!indio_dev) {
dev_err(dev, "failed allocating iio device\n");
return -ENOMEM;
}
st = iio_priv(indio_dev);
st->np = np;
/*
* SPEAr600 has a different register layout than other SPEAr SoC's
* (e.g. SPEAr3xx). Let's provide two register base addresses
* to support multi-arch kernels.
*/
st->adc_base_spear6xx = of_iomap(np, 0);
if (!st->adc_base_spear6xx) {
dev_err(dev, "failed mapping memory\n");
return -ENOMEM;
}
st->adc_base_spear3xx =
(struct adc_regs_spear3xx __iomem *)st->adc_base_spear6xx;
st->clk = devm_clk_get(dev, NULL);
if (IS_ERR(st->clk)) {
dev_err(dev, "failed getting clock\n");
goto errout1;
}
ret = clk_prepare_enable(st->clk);
if (ret) {
dev_err(dev, "failed enabling clock\n");
goto errout1;
}
irq = platform_get_irq(pdev, 0);
if (irq <= 0) {
dev_err(dev, "failed getting interrupt resource\n");
ret = -EINVAL;
goto errout2;
}
ret = devm_request_irq(dev, irq, spear_adc_isr, 0, SPEAR_ADC_MOD_NAME,
st);
if (ret < 0) {
dev_err(dev, "failed requesting interrupt\n");
goto errout2;
}
if (of_property_read_u32(np, "sampling-frequency",
&st->sampling_freq)) {
dev_err(dev, "sampling-frequency missing in DT\n");
ret = -EINVAL;
goto errout2;
}
/*
* Optional avg_samples defaults to 0, resulting in single data
* conversion
*/
of_property_read_u32(np, "average-samples", &st->avg_samples);
/*
* Optional vref_external defaults to 0, resulting in internal vref
* selection
*/
of_property_read_u32(np, "vref-external", &st->vref_external);
spear_adc_configure(st);
platform_set_drvdata(pdev, indio_dev);
init_completion(&st->completion);
indio_dev->name = SPEAR_ADC_MOD_NAME;
indio_dev->dev.parent = dev;
indio_dev->info = &spear_adc_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = spear_adc_iio_channels;
indio_dev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);
ret = iio_device_register(indio_dev);
if (ret)
goto errout2;
dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);
return 0;
errout2:
clk_disable_unprepare(st->clk);
errout1:
iounmap(st->adc_base_spear6xx);
return ret;
}
static int spear_adc_remove(struct platform_device *pdev)
{
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct spear_adc_state *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
clk_disable_unprepare(st->clk);
iounmap(st->adc_base_spear6xx);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id spear_adc_dt_ids[] = {
{ .compatible = "st,spear600-adc", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
#endif
static struct platform_driver spear_adc_driver = {
.probe = spear_adc_probe,
.remove = spear_adc_remove,
.driver = {
.name = SPEAR_ADC_MOD_NAME,
.of_match_table = of_match_ptr(spear_adc_dt_ids),
},
};
module_platform_driver(spear_adc_driver);
MODULE_AUTHOR("Stefan Roese <sr@denx.de>");
MODULE_DESCRIPTION("SPEAr ADC driver");
MODULE_LICENSE("GPL");
|