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> 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> 20 21#include <linux/iio/iio.h> 22#include <linux/iio/trigger_consumer.h> 23#include <linux/iio/kfifo_buf.h> 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 * 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. 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 int len = 0; 50 u16 *data; 51 52 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL); 53 if (!data) 54 goto done; 55 56 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) { 57 /* 58 * Three common options here: 59 * hardware scans: certain combinations of channels make 60 * up a fast read. The capture will consist of all of them. 61 * Hence we just call the grab data function and fill the 62 * buffer without processing. 63 * software scans: can be considered to be random access 64 * so efficient reading is just a case of minimal bus 65 * transactions. 66 * software culled hardware scans: 67 * occasionally a driver may process the nearest hardware 68 * scan to avoid storing elements that are not desired. This 69 * is the fiddliest option by far. 70 * Here let's pretend we have random access. And the values are 71 * in the constant table fakedata. 72 */ 73 int i, j; 74 75 for (i = 0, j = 0; 76 i < bitmap_weight(indio_dev->active_scan_mask, 77 indio_dev->masklength); 78 i++, j++) { 79 j = find_next_bit(indio_dev->active_scan_mask, 80 indio_dev->masklength, j); 81 /* random access read from the 'device' */ 82 data[i] = fakedata[j]; 83 len += 2; 84 } 85 } 86 87 iio_push_to_buffers_with_timestamp(indio_dev, data, iio_get_time_ns()); 88 89 kfree(data); 90 91done: 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 101static 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 118int 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 /* Enable timestamps by default */ 133 buffer->scan_timestamp = true; 134 135 /* 136 * Tell the core what device type specific functions should 137 * be run on either side of buffer capture enable / disable. 138 */ 139 indio_dev->setup_ops = &iio_simple_dummy_buffer_setup_ops; 140 141 /* 142 * Configure a polling function. 143 * When a trigger event with this polling function connected 144 * occurs, this function is run. Typically this grabs data 145 * from the device. 146 * 147 * NULL for the bottom half. This is normally implemented only if we 148 * either want to ping a capture now pin (no sleeping) or grab 149 * a timestamp as close as possible to a data ready trigger firing. 150 * 151 * IRQF_ONESHOT ensures irqs are masked such that only one instance 152 * of the handler can run at a time. 153 * 154 * "iio_simple_dummy_consumer%d" formatting string for the irq 'name' 155 * as seen under /proc/interrupts. Remaining parameters as per printk. 156 */ 157 indio_dev->pollfunc = iio_alloc_pollfunc(NULL, 158 &iio_simple_dummy_trigger_h, 159 IRQF_ONESHOT, 160 indio_dev, 161 "iio_simple_dummy_consumer%d", 162 indio_dev->id); 163 164 if (!indio_dev->pollfunc) { 165 ret = -ENOMEM; 166 goto error_free_buffer; 167 } 168 169 /* 170 * Notify the core that this device is capable of buffered capture 171 * driven by a trigger. 172 */ 173 indio_dev->modes |= INDIO_BUFFER_TRIGGERED; 174 175 return 0; 176 177error_free_buffer: 178 iio_kfifo_free(indio_dev->buffer); 179error_ret: 180 return ret; 181 182} 183 184/** 185 * iio_simple_dummy_unconfigure_buffer() - release buffer resources 186 * @indo_dev: device instance state 187 */ 188void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev) 189{ 190 iio_dealloc_pollfunc(indio_dev->pollfunc); 191 iio_kfifo_free(indio_dev->buffer); 192} 193