IIO: Add 4-byte unsigned reads into generic-buffer example
[deliverable/linux.git] / drivers / staging / iio / iio_simple_dummy_buffer.c
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1/**
2 * Copyright (c) 2011 Jonathan Cameron
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 as published by
6 * the Free Software Foundation.
7 *
8 * Buffer handling elements of industrial I/O reference driver.
9 * Uses the kfifo buffer.
10 *
11 * To test without hardware use the sysfs trigger.
12 */
13
14#include <linux/kernel.h>
8e336a72 15#include <linux/export.h>
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16#include <linux/slab.h>
17#include <linux/interrupt.h>
18#include <linux/irq.h>
19#include <linux/bitmap.h>
20
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21#include <linux/iio/iio.h>
22#include <linux/iio/trigger_consumer.h>
23#include <linux/iio/kfifo_buf.h>
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24
25#include "iio_simple_dummy.h"
26
27/* Some fake data */
28
29static const s16 fakedata[] = {
30 [voltage0] = 7,
31 [diffvoltage1m2] = -33,
32 [diffvoltage3m4] = -2,
33 [accelx] = 344,
34};
35/**
36 * iio_simple_dummy_trigger_h() - the trigger handler function
37 * @irq: the interrupt number
38 * @p: private data - always a pointer to the poll func.
39 *
99de0c2b 40 * This is the guts of buffered capture. On a trigger event occurring,
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41 * if the pollfunc is attached then this handler is called as a threaded
42 * interrupt (and hence may sleep). It is responsible for grabbing data
43 * from the device and pushing it into the associated buffer.
44 */
45static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
46{
47 struct iio_poll_func *pf = p;
48 struct iio_dev *indio_dev = pf->indio_dev;
49 struct iio_buffer *buffer = indio_dev->buffer;
50 int len = 0;
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51 u16 *data;
52
53 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
9ad2e2e1 54 if (data == NULL)
a1bdeefd 55 goto done;
9ad2e2e1 56
550268ca 57 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) {
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58 /*
59 * Three common options here:
60 * hardware scans: certain combinations of channels make
61 * up a fast read. The capture will consist of all of them.
62 * Hence we just call the grab data function and fill the
63 * buffer without processing.
99de0c2b 64 * software scans: can be considered to be random access
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65 * so efficient reading is just a case of minimal bus
66 * transactions.
67 * software culled hardware scans:
68 * occasionally a driver may process the nearest hardware
69 * scan to avoid storing elements that are not desired. This
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70 * is the fiddliest option by far.
71 * Here let's pretend we have random access. And the values are
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72 * in the constant table fakedata.
73 */
74 int i, j;
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75 for (i = 0, j = 0;
76 i < bitmap_weight(indio_dev->active_scan_mask,
77 indio_dev->masklength);
708706ff 78 i++, j++) {
9ad2e2e1 79 j = find_next_bit(buffer->scan_mask,
708706ff 80 indio_dev->masklength, j);
d163a19d 81 /* random access read from the 'device' */
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82 data[i] = fakedata[j];
83 len += 2;
84 }
85 }
8b32b11c 86 /* Store the timestamp at an 8 byte aligned offset */
fd6487f8 87 if (indio_dev->scan_timestamp)
be344c84 88 *(s64 *)((u8 *)data + ALIGN(len, sizeof(s64)))
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89 = iio_get_time_ns();
90 buffer->access->store_to(buffer, (u8 *)data, pf->timestamp);
91
92 kfree(data);
93
a1bdeefd 94done:
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95 /*
96 * Tell the core we are done with this trigger and ready for the
97 * next one.
98 */
99 iio_trigger_notify_done(indio_dev->trig);
100
101 return IRQ_HANDLED;
102}
103
104static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
105 /*
106 * iio_sw_buffer_preenable:
107 * Generic function for equal sized ring elements + 64 bit timestamp
108 * Assumes that any combination of channels can be enabled.
109 * Typically replaced to implement restrictions on what combinations
110 * can be captured (hardware scan modes).
111 */
112 .preenable = &iio_sw_buffer_preenable,
113 /*
114 * iio_triggered_buffer_postenable:
115 * Generic function that simply attaches the pollfunc to the trigger.
116 * Replace this to mess with hardware state before we attach the
117 * trigger.
118 */
119 .postenable = &iio_triggered_buffer_postenable,
120 /*
121 * iio_triggered_buffer_predisable:
122 * Generic function that simple detaches the pollfunc from the trigger.
123 * Replace this to put hardware state back again after the trigger is
124 * detached but before userspace knows we have disabled the ring.
125 */
126 .predisable = &iio_triggered_buffer_predisable,
127};
128
129int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
130{
131 int ret;
132 struct iio_buffer *buffer;
133
134 /* Allocate a buffer to use - here a kfifo */
135 buffer = iio_kfifo_allocate(indio_dev);
136 if (buffer == NULL) {
137 ret = -ENOMEM;
138 goto error_ret;
139 }
140
141 indio_dev->buffer = buffer;
9ad2e2e1 142
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143 /* Enable timestamps by default */
144 buffer->scan_timestamp = true;
145
146 /*
147 * Tell the core what device type specific functions should
148 * be run on either side of buffer capture enable / disable.
149 */
1612244f 150 indio_dev->setup_ops = &iio_simple_dummy_buffer_setup_ops;
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151
152 /*
153 * Configure a polling function.
154 * When a trigger event with this polling function connected
155 * occurs, this function is run. Typically this grabs data
156 * from the device.
157 *
158 * NULL for the top half. This is normally implemented only if we
159 * either want to ping a capture now pin (no sleeping) or grab
160 * a timestamp as close as possible to a data ready trigger firing.
161 *
162 * IRQF_ONESHOT ensures irqs are masked such that only one instance
163 * of the handler can run at a time.
164 *
165 * "iio_simple_dummy_consumer%d" formatting string for the irq 'name'
166 * as seen under /proc/interrupts. Remaining parameters as per printk.
167 */
168 indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
169 &iio_simple_dummy_trigger_h,
170 IRQF_ONESHOT,
171 indio_dev,
172 "iio_simple_dummy_consumer%d",
173 indio_dev->id);
174
175 if (indio_dev->pollfunc == NULL) {
176 ret = -ENOMEM;
177 goto error_free_buffer;
178 }
179
180 /*
181 * Notify the core that this device is capable of buffered capture
182 * driven by a trigger.
183 */
184 indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
185 return 0;
186
187error_free_buffer:
188 iio_kfifo_free(indio_dev->buffer);
189error_ret:
190 return ret;
191
192}
193
194/**
195 * iio_simple_dummy_unconfigure_buffer() - release buffer resources
196 * @indo_dev: device instance state
197 */
198void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
199{
200 iio_dealloc_pollfunc(indio_dev->pollfunc);
201 iio_kfifo_free(indio_dev->buffer);
202}
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