1 // SPDX-License-Identifier: GPL-2.0-only
2 /**
3 * Copyright (c) 2011 Jonathan Cameron
4 *
5 * Buffer handling elements of industrial I/O reference driver.
6 * Uses the kfifo buffer.
7 *
8 * To test without hardware use the sysfs trigger.
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/export.h>
13 #include <linux/slab.h>
14 #include <linux/interrupt.h>
15 #include <linux/irq.h>
16 #include <linux/bitmap.h>
17
18 #include <linux/iio/iio.h>
19 #include <linux/iio/trigger_consumer.h>
20 #include <linux/iio/buffer.h>
21 #include <linux/iio/kfifo_buf.h>
22
23 #include "iio_simple_dummy.h"
24
25 /* Some fake data */
26
27 static const s16 fakedata[] = {
28 [DUMMY_INDEX_VOLTAGE_0] = 7,
29 [DUMMY_INDEX_DIFFVOLTAGE_1M2] = -33,
30 [DUMMY_INDEX_DIFFVOLTAGE_3M4] = -2,
31 [DUMMY_INDEX_ACCELX] = 344,
32 };
33
34 /**
35 * iio_simple_dummy_trigger_h() - the trigger handler function
36 * @irq: the interrupt number
37 * @p: private data - always a pointer to the poll func.
38 *
39 * This is the guts of buffered capture. On a trigger event occurring,
40 * if the pollfunc is attached then this handler is called as a threaded
41 * interrupt (and hence may sleep). It is responsible for grabbing data
42 * from the device and pushing it into the associated buffer.
43 */
44 static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
45 {
46 struct iio_poll_func *pf = p;
47 struct iio_dev *indio_dev = pf->indio_dev;
48 int len = 0;
49 u16 *data;
50
51 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
52 if (!data)
53 goto done;
54
55 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) {
56 /*
57 * Three common options here:
58 * hardware scans: certain combinations of channels make
59 * up a fast read. The capture will consist of all of them.
60 * Hence we just call the grab data function and fill the
61 * buffer without processing.
62 * software scans: can be considered to be random access
63 * so efficient reading is just a case of minimal bus
64 * transactions.
65 * software culled hardware scans:
66 * occasionally a driver may process the nearest hardware
67 * scan to avoid storing elements that are not desired. This
68 * is the fiddliest option by far.
69 * Here let's pretend we have random access. And the values are
70 * in the constant table fakedata.
71 */
72 int i, j;
73
74 for (i = 0, j = 0;
75 i < bitmap_weight(indio_dev->active_scan_mask,
76 indio_dev->masklength);
77 i++, j++) {
78 j = find_next_bit(indio_dev->active_scan_mask,
79 indio_dev->masklength, j);
80 /* random access read from the 'device' */
81 data[i] = fakedata[j];
82 len += 2;
83 }
84 }
85
86 iio_push_to_buffers_with_timestamp(indio_dev, data,
87 iio_get_time_ns(indio_dev));
88
89 kfree(data);
90
91 done:
92 /*
93 * Tell the core we are done with this trigger and ready for the
94 * next one.
95 */
96 iio_trigger_notify_done(indio_dev->trig);
97
98 return IRQ_HANDLED;
99 }
100
101 static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
102 /*
103 * iio_triggered_buffer_postenable:
104 * Generic function that simply attaches the pollfunc to the trigger.
105 * Replace this to mess with hardware state before we attach the
106 * trigger.
107 */
108 .postenable = &iio_triggered_buffer_postenable,
109 /*
110 * iio_triggered_buffer_predisable:
111 * Generic function that simple detaches the pollfunc from the trigger.
112 * Replace this to put hardware state back again after the trigger is
113 * detached but before userspace knows we have disabled the ring.
114 */
115 .predisable = &iio_triggered_buffer_predisable,
116 };
117
118 int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
119 {
120 int ret;
121 struct iio_buffer *buffer;
122
123 /* Allocate a buffer to use - here a kfifo */
124 buffer = iio_kfifo_allocate();
125 if (!buffer) {
126 ret = -ENOMEM;
127 goto error_ret;
128 }
129
130 iio_device_attach_buffer(indio_dev, buffer);
131
132 /*
133 * Tell the core what device type specific functions should
134 * be run on either side of buffer capture enable / disable.
135 */
136 indio_dev->setup_ops = &iio_simple_dummy_buffer_setup_ops;
137
138 /*
139 * Configure a polling function.
140 * When a trigger event with this polling function connected
141 * occurs, this function is run. Typically this grabs data
142 * from the device.
143 *
144 * NULL for the bottom half. This is normally implemented only if we
145 * either want to ping a capture now pin (no sleeping) or grab
146 * a timestamp as close as possible to a data ready trigger firing.
147 *
148 * IRQF_ONESHOT ensures irqs are masked such that only one instance
149 * of the handler can run at a time.
150 *
151 * "iio_simple_dummy_consumer%d" formatting string for the irq 'name'
152 * as seen under /proc/interrupts. Remaining parameters as per printk.
153 */
154 indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
155 &iio_simple_dummy_trigger_h,
156 IRQF_ONESHOT,
157 indio_dev,
158 "iio_simple_dummy_consumer%d",
159 indio_dev->id);
160
161 if (!indio_dev->pollfunc) {
162 ret = -ENOMEM;
163 goto error_free_buffer;
164 }
165
166 /*
167 * Notify the core that this device is capable of buffered capture
168 * driven by a trigger.
169 */
170 indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
171
172 return 0;
173
174 error_free_buffer:
175 iio_kfifo_free(indio_dev->buffer);
176 error_ret:
177 return ret;
178 }
179
180 /**
181 * iio_simple_dummy_unconfigure_buffer() - release buffer resources
182 * @indo_dev: device instance state
183 */
184 void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
185 {
186 iio_dealloc_pollfunc(indio_dev->pollfunc);
187 iio_kfifo_free(indio_dev->buffer);
188 }