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iio: Add reference counting for buffers
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1#include <linux/interrupt.h>
2#include <linux/gpio.h>
3#include <linux/mutex.h>
4#include <linux/kernel.h>
5#include <linux/spi/spi.h>
6#include <linux/slab.h>
7#include <linux/export.h>
8
9#include <linux/iio/iio.h>
10#include <linux/iio/kfifo_buf.h>
11#include <linux/iio/trigger.h>
12#include <linux/iio/trigger_consumer.h>
13#include "lis3l02dq.h"
14
15/**
16 * combine_8_to_16() utility function to munge two u8s into u16
17 **/
18static inline u16 combine_8_to_16(u8 lower, u8 upper)
19{
20 u16 _lower = lower;
21 u16 _upper = upper;
22 return _lower | (_upper << 8);
23}
24
25/**
26 * lis3l02dq_data_rdy_trig_poll() the event handler for the data rdy trig
27 **/
28irqreturn_t lis3l02dq_data_rdy_trig_poll(int irq, void *private)
29{
30 struct iio_dev *indio_dev = private;
31 struct lis3l02dq_state *st = iio_priv(indio_dev);
32
33 if (st->trigger_on) {
34 iio_trigger_poll(st->trig, iio_get_time_ns());
35 return IRQ_HANDLED;
36 } else
37 return IRQ_WAKE_THREAD;
38}
39
40static const u8 read_all_tx_array[] = {
41 LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_X_L_ADDR), 0,
42 LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_X_H_ADDR), 0,
43 LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Y_L_ADDR), 0,
44 LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Y_H_ADDR), 0,
45 LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Z_L_ADDR), 0,
46 LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Z_H_ADDR), 0,
47};
48
49/**
50 * lis3l02dq_read_all() Reads all channels currently selected
51 * @indio_dev: IIO device state
52 * @rx_array: (dma capable) receive array, must be at least
53 * 4*number of channels
54 **/
55static int lis3l02dq_read_all(struct iio_dev *indio_dev, u8 *rx_array)
56{
57 struct lis3l02dq_state *st = iio_priv(indio_dev);
58 struct spi_transfer *xfers;
59 struct spi_message msg;
60 int ret, i, j = 0;
61
62 xfers = kcalloc(bitmap_weight(indio_dev->active_scan_mask,
63 indio_dev->masklength) * 2,
64 sizeof(*xfers), GFP_KERNEL);
65 if (!xfers)
66 return -ENOMEM;
67
68 mutex_lock(&st->buf_lock);
69
70 for (i = 0; i < ARRAY_SIZE(read_all_tx_array)/4; i++)
71 if (test_bit(i, indio_dev->active_scan_mask)) {
72 /* lower byte */
73 xfers[j].tx_buf = st->tx + 2*j;
74 st->tx[2*j] = read_all_tx_array[i*4];
75 st->tx[2*j + 1] = 0;
76 if (rx_array)
77 xfers[j].rx_buf = rx_array + j*2;
78 xfers[j].bits_per_word = 8;
79 xfers[j].len = 2;
80 xfers[j].cs_change = 1;
81 j++;
82
83 /* upper byte */
84 xfers[j].tx_buf = st->tx + 2*j;
85 st->tx[2*j] = read_all_tx_array[i*4 + 2];
86 st->tx[2*j + 1] = 0;
87 if (rx_array)
88 xfers[j].rx_buf = rx_array + j*2;
89 xfers[j].bits_per_word = 8;
90 xfers[j].len = 2;
91 xfers[j].cs_change = 1;
92 j++;
93 }
94
95 /* After these are transmitted, the rx_buff should have
96 * values in alternate bytes
97 */
98 spi_message_init(&msg);
99 for (j = 0; j < bitmap_weight(indio_dev->active_scan_mask,
100 indio_dev->masklength) * 2; j++)
101 spi_message_add_tail(&xfers[j], &msg);
102
103 ret = spi_sync(st->us, &msg);
104 mutex_unlock(&st->buf_lock);
105 kfree(xfers);
106
107 return ret;
108}
109
110static int lis3l02dq_get_buffer_element(struct iio_dev *indio_dev,
111 u8 *buf)
112{
113 int ret, i;
114 u8 *rx_array;
115 s16 *data = (s16 *)buf;
116 int scan_count = bitmap_weight(indio_dev->active_scan_mask,
117 indio_dev->masklength);
118
119 rx_array = kzalloc(4 * scan_count, GFP_KERNEL);
120 if (rx_array == NULL)
121 return -ENOMEM;
122 ret = lis3l02dq_read_all(indio_dev, rx_array);
123 if (ret < 0) {
124 kfree(rx_array);
125 return ret;
126 }
127 for (i = 0; i < scan_count; i++)
128 data[i] = combine_8_to_16(rx_array[i*4+1],
129 rx_array[i*4+3]);
130 kfree(rx_array);
131
132 return i*sizeof(data[0]);
133}
134
135static irqreturn_t lis3l02dq_trigger_handler(int irq, void *p)
136{
137 struct iio_poll_func *pf = p;
138 struct iio_dev *indio_dev = pf->indio_dev;
139 int len = 0;
140 char *data;
141
142 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
143 if (data == NULL)
144 goto done;
145
146 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength))
147 len = lis3l02dq_get_buffer_element(indio_dev, data);
148
149 iio_push_to_buffers_with_timestamp(indio_dev, data, pf->timestamp);
150
151 kfree(data);
152done:
153 iio_trigger_notify_done(indio_dev->trig);
154 return IRQ_HANDLED;
155}
156
157/* Caller responsible for locking as necessary. */
158static int
159__lis3l02dq_write_data_ready_config(struct iio_dev *indio_dev, bool state)
160{
161 int ret;
162 u8 valold;
163 bool currentlyset;
164 struct lis3l02dq_state *st = iio_priv(indio_dev);
165
166 /* Get the current event mask register */
167 ret = lis3l02dq_spi_read_reg_8(indio_dev,
168 LIS3L02DQ_REG_CTRL_2_ADDR,
169 &valold);
170 if (ret)
171 goto error_ret;
172 /* Find out if data ready is already on */
173 currentlyset
174 = valold & LIS3L02DQ_REG_CTRL_2_ENABLE_DATA_READY_GENERATION;
175
176 /* Disable requested */
177 if (!state && currentlyset) {
178 /* Disable the data ready signal */
179 valold &= ~LIS3L02DQ_REG_CTRL_2_ENABLE_DATA_READY_GENERATION;
180
181 /* The double write is to overcome a hardware bug? */
182 ret = lis3l02dq_spi_write_reg_8(indio_dev,
183 LIS3L02DQ_REG_CTRL_2_ADDR,
184 valold);
185 if (ret)
186 goto error_ret;
187 ret = lis3l02dq_spi_write_reg_8(indio_dev,
188 LIS3L02DQ_REG_CTRL_2_ADDR,
189 valold);
190 if (ret)
191 goto error_ret;
192 st->trigger_on = false;
193 /* Enable requested */
194 } else if (state && !currentlyset) {
195 /* If not set, enable requested
196 * first disable all events */
197 ret = lis3l02dq_disable_all_events(indio_dev);
198 if (ret < 0)
199 goto error_ret;
200
201 valold = ret |
202 LIS3L02DQ_REG_CTRL_2_ENABLE_DATA_READY_GENERATION;
203
204 st->trigger_on = true;
205 ret = lis3l02dq_spi_write_reg_8(indio_dev,
206 LIS3L02DQ_REG_CTRL_2_ADDR,
207 valold);
208 if (ret)
209 goto error_ret;
210 }
211
212 return 0;
213error_ret:
214 return ret;
215}
216
217/**
218 * lis3l02dq_data_rdy_trigger_set_state() set datardy interrupt state
219 *
220 * If disabling the interrupt also does a final read to ensure it is clear.
221 * This is only important in some cases where the scan enable elements are
222 * switched before the buffer is reenabled.
223 **/
224static int lis3l02dq_data_rdy_trigger_set_state(struct iio_trigger *trig,
225 bool state)
226{
227 struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
228 int ret = 0;
229 u8 t;
230
231 __lis3l02dq_write_data_ready_config(indio_dev, state);
232 if (!state) {
233 /*
234 * A possible quirk with the handler is currently worked around
235 * by ensuring outstanding read events are cleared.
236 */
237 ret = lis3l02dq_read_all(indio_dev, NULL);
238 }
239 lis3l02dq_spi_read_reg_8(indio_dev,
240 LIS3L02DQ_REG_WAKE_UP_SRC_ADDR,
241 &t);
242 return ret;
243}
244
245/**
246 * lis3l02dq_trig_try_reen() try reenabling irq for data rdy trigger
247 * @trig: the datardy trigger
248 */
249static int lis3l02dq_trig_try_reen(struct iio_trigger *trig)
250{
251 struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
252 struct lis3l02dq_state *st = iio_priv(indio_dev);
253 int i;
254
255 /* If gpio still high (or high again)
256 * In theory possible we will need to do this several times */
257 for (i = 0; i < 5; i++)
258 if (gpio_get_value(st->gpio))
259 lis3l02dq_read_all(indio_dev, NULL);
260 else
261 break;
262 if (i == 5)
263 pr_info("Failed to clear the interrupt for lis3l02dq\n");
264
265 /* irq reenabled so success! */
266 return 0;
267}
268
269static const struct iio_trigger_ops lis3l02dq_trigger_ops = {
270 .owner = THIS_MODULE,
271 .set_trigger_state = &lis3l02dq_data_rdy_trigger_set_state,
272 .try_reenable = &lis3l02dq_trig_try_reen,
273};
274
275int lis3l02dq_probe_trigger(struct iio_dev *indio_dev)
276{
277 int ret;
278 struct lis3l02dq_state *st = iio_priv(indio_dev);
279
280 st->trig = iio_trigger_alloc("lis3l02dq-dev%d", indio_dev->id);
281 if (!st->trig) {
282 ret = -ENOMEM;
283 goto error_ret;
284 }
285
286 st->trig->dev.parent = &st->us->dev;
287 st->trig->ops = &lis3l02dq_trigger_ops;
288 iio_trigger_set_drvdata(st->trig, indio_dev);
289 ret = iio_trigger_register(st->trig);
290 if (ret)
291 goto error_free_trig;
292
293 return 0;
294
295error_free_trig:
296 iio_trigger_free(st->trig);
297error_ret:
298 return ret;
299}
300
301void lis3l02dq_remove_trigger(struct iio_dev *indio_dev)
302{
303 struct lis3l02dq_state *st = iio_priv(indio_dev);
304
305 iio_trigger_unregister(st->trig);
306 iio_trigger_free(st->trig);
307}
308
309void lis3l02dq_unconfigure_buffer(struct iio_dev *indio_dev)
310{
311 iio_dealloc_pollfunc(indio_dev->pollfunc);
312 iio_kfifo_free(indio_dev->buffer);
313}
314
315static int lis3l02dq_buffer_postenable(struct iio_dev *indio_dev)
316{
317 /* Disable unwanted channels otherwise the interrupt will not clear */
318 u8 t;
319 int ret;
320 bool oneenabled = false;
321
322 ret = lis3l02dq_spi_read_reg_8(indio_dev,
323 LIS3L02DQ_REG_CTRL_1_ADDR,
324 &t);
325 if (ret)
326 goto error_ret;
327
328 if (test_bit(0, indio_dev->active_scan_mask)) {
329 t |= LIS3L02DQ_REG_CTRL_1_AXES_X_ENABLE;
330 oneenabled = true;
331 } else
332 t &= ~LIS3L02DQ_REG_CTRL_1_AXES_X_ENABLE;
333 if (test_bit(1, indio_dev->active_scan_mask)) {
334 t |= LIS3L02DQ_REG_CTRL_1_AXES_Y_ENABLE;
335 oneenabled = true;
336 } else
337 t &= ~LIS3L02DQ_REG_CTRL_1_AXES_Y_ENABLE;
338 if (test_bit(2, indio_dev->active_scan_mask)) {
339 t |= LIS3L02DQ_REG_CTRL_1_AXES_Z_ENABLE;
340 oneenabled = true;
341 } else
342 t &= ~LIS3L02DQ_REG_CTRL_1_AXES_Z_ENABLE;
343
344 if (!oneenabled) /* what happens in this case is unknown */
345 return -EINVAL;
346 ret = lis3l02dq_spi_write_reg_8(indio_dev,
347 LIS3L02DQ_REG_CTRL_1_ADDR,
348 t);
349 if (ret)
350 goto error_ret;
351
352 return iio_triggered_buffer_postenable(indio_dev);
353error_ret:
354 return ret;
355}
356
357/* Turn all channels on again */
358static int lis3l02dq_buffer_predisable(struct iio_dev *indio_dev)
359{
360 u8 t;
361 int ret;
362
363 ret = iio_triggered_buffer_predisable(indio_dev);
364 if (ret)
365 goto error_ret;
366
367 ret = lis3l02dq_spi_read_reg_8(indio_dev,
368 LIS3L02DQ_REG_CTRL_1_ADDR,
369 &t);
370 if (ret)
371 goto error_ret;
372 t |= LIS3L02DQ_REG_CTRL_1_AXES_X_ENABLE |
373 LIS3L02DQ_REG_CTRL_1_AXES_Y_ENABLE |
374 LIS3L02DQ_REG_CTRL_1_AXES_Z_ENABLE;
375
376 ret = lis3l02dq_spi_write_reg_8(indio_dev,
377 LIS3L02DQ_REG_CTRL_1_ADDR,
378 t);
379
380error_ret:
381 return ret;
382}
383
384static const struct iio_buffer_setup_ops lis3l02dq_buffer_setup_ops = {
385 .preenable = &iio_sw_buffer_preenable,
386 .postenable = &lis3l02dq_buffer_postenable,
387 .predisable = &lis3l02dq_buffer_predisable,
388};
389
390int lis3l02dq_configure_buffer(struct iio_dev *indio_dev)
391{
392 int ret;
393 struct iio_buffer *buffer;
394
395 buffer = iio_kfifo_allocate(indio_dev);
396 if (!buffer)
397 return -ENOMEM;
398
399 iio_device_attach_buffer(indio_dev, buffer);
400
401 buffer->scan_timestamp = true;
402 indio_dev->setup_ops = &lis3l02dq_buffer_setup_ops;
403
404 /* Functions are NULL as we set handler below */
405 indio_dev->pollfunc = iio_alloc_pollfunc(&iio_pollfunc_store_time,
406 &lis3l02dq_trigger_handler,
407 0,
408 indio_dev,
409 "lis3l02dq_consumer%d",
410 indio_dev->id);
411
412 if (indio_dev->pollfunc == NULL) {
413 ret = -ENOMEM;
414 goto error_iio_sw_rb_free;
415 }
416
417 indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
418 return 0;
419
420error_iio_sw_rb_free:
421 iio_kfifo_free(indio_dev->buffer);
422 return ret;
423}