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 }
189