2 * Copyright (c) 2011 Jonathan Cameron
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.
8 * Buffer handling elements of industrial I/O reference driver.
9 * Uses the kfifo buffer.
11 * To test without hardware use the sysfs trigger.
14 #include <linux/kernel.h>
15 #include <linux/export.h>
16 #include <linux/slab.h>
17 #include <linux/interrupt.h>
18 #include <linux/irq.h>
19 #include <linux/bitmap.h>
21 #include <linux/iio/iio.h>
22 #include <linux/iio/trigger_consumer.h>
23 #include <linux/iio/kfifo_buf.h>
25 #include "iio_simple_dummy.h"
29 static const s16 fakedata[] = {
31 [diffvoltage1m2] = -33,
32 [diffvoltage3m4] = -2,
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.
40 * This is the guts of buffered capture. On a trigger event occurring,
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.
45 static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p)
47 struct iio_poll_func *pf = p;
48 struct iio_dev *indio_dev = pf->indio_dev;
49 struct iio_buffer *buffer = indio_dev->buffer;
53 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
57 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) {
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.
64 * software scans: can be considered to be random access
65 * so efficient reading is just a case of minimal bus
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
70 * is the fidliest option by far.
71 * Here lets pretend we have random access. And the values are
72 * in the constant table fakedata.
76 i < bitmap_weight(indio_dev->active_scan_mask,
77 indio_dev->masklength);
79 j = find_next_bit(buffer->scan_mask,
80 indio_dev->masklength, j + 1);
81 /* random access read form the 'device' */
82 data[i] = fakedata[j];
86 /* Store a timestampe at an 8 byte boundary */
87 if (indio_dev->scan_timestamp)
88 *(s64 *)(((phys_addr_t)data + len
89 + sizeof(s64) - 1) & ~(sizeof(s64) - 1))
91 buffer->access->store_to(buffer, (u8 *)data, pf->timestamp);
96 * Tell the core we are done with this trigger and ready for the
99 iio_trigger_notify_done(indio_dev->trig);
104 static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = {
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).
112 .preenable = &iio_sw_buffer_preenable,
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
119 .postenable = &iio_triggered_buffer_postenable,
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.
126 .predisable = &iio_triggered_buffer_predisable,
129 int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
132 struct iio_buffer *buffer;
134 /* Allocate a buffer to use - here a kfifo */
135 buffer = iio_kfifo_allocate(indio_dev);
136 if (buffer == NULL) {
141 indio_dev->buffer = buffer;
143 /* Enable timestamps by default */
144 buffer->scan_timestamp = true;
147 * Tell the core what device type specific functions should
148 * be run on either side of buffer capture enable / disable.
150 indio_dev->setup_ops = &iio_simple_dummy_buffer_setup_ops;
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
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.
162 * IRQF_ONESHOT ensures irqs are masked such that only one instance
163 * of the handler can run at a time.
165 * "iio_simple_dummy_consumer%d" formatting string for the irq 'name'
166 * as seen under /proc/interrupts. Remaining parameters as per printk.
168 indio_dev->pollfunc = iio_alloc_pollfunc(NULL,
169 &iio_simple_dummy_trigger_h,
172 "iio_simple_dummy_consumer%d",
175 if (indio_dev->pollfunc == NULL) {
177 goto error_free_buffer;
181 * Notify the core that this device is capable of buffered capture
182 * driven by a trigger.
184 indio_dev->modes |= INDIO_BUFFER_TRIGGERED;
188 iio_kfifo_free(indio_dev->buffer);
195 * iio_simple_dummy_unconfigure_buffer() - release buffer resources
196 * @indo_dev: device instance state
198 void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev)
200 iio_dealloc_pollfunc(indio_dev->pollfunc);
201 iio_kfifo_free(indio_dev->buffer);