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 29 static const s16 fakedata[] = { 30 [DUMMY_INDEX_VOLTAGE_0] = 7, 31 [DUMMY_INDEX_DIFFVOLTAGE_1M2] = -33, 32 [DUMMY_INDEX_DIFFVOLTAGE_3M4] = -2, 33 [DUMMY_INDEX_ACCELX] = 344, 34 }; 35 36 /** 37 * iio_simple_dummy_trigger_h() - the trigger handler function 38 * @irq: the interrupt number 39 * @p: private data - always a pointer to the poll func. 40 * 41 * This is the guts of buffered capture. On a trigger event occurring, 42 * if the pollfunc is attached then this handler is called as a threaded 43 * interrupt (and hence may sleep). It is responsible for grabbing data 44 * from the device and pushing it into the associated buffer. 45 */ 46 static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p) 47 { 48 struct iio_poll_func *pf = p; 49 struct iio_dev *indio_dev = pf->indio_dev; 50 int len = 0; 51 u16 *data; 52 53 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL); 54 if (!data) 55 goto done; 56 57 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) { 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. 64 * software scans: can be considered to be random access 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 70 * is the fiddliest option by far. 71 * Here let's pretend we have random access. And the values are 72 * in the constant table fakedata. 73 */ 74 int i, j; 75 76 for (i = 0, j = 0; 77 i < bitmap_weight(indio_dev->active_scan_mask, 78 indio_dev->masklength); 79 i++, j++) { 80 j = find_next_bit(indio_dev->active_scan_mask, 81 indio_dev->masklength, j); 82 /* random access read from the 'device' */ 83 data[i] = fakedata[j]; 84 len += 2; 85 } 86 } 87 88 iio_push_to_buffers_with_timestamp(indio_dev, data, 89 iio_get_time_ns(indio_dev)); 90 91 kfree(data); 92 93 done: 94 /* 95 * Tell the core we are done with this trigger and ready for the 96 * next one. 97 */ 98 iio_trigger_notify_done(indio_dev->trig); 99 100 return IRQ_HANDLED; 101 } 102 103 static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = { 104 /* 105 * iio_triggered_buffer_postenable: 106 * Generic function that simply attaches the pollfunc to the trigger. 107 * Replace this to mess with hardware state before we attach the 108 * trigger. 109 */ 110 .postenable = &iio_triggered_buffer_postenable, 111 /* 112 * iio_triggered_buffer_predisable: 113 * Generic function that simple detaches the pollfunc from the trigger. 114 * Replace this to put hardware state back again after the trigger is 115 * detached but before userspace knows we have disabled the ring. 116 */ 117 .predisable = &iio_triggered_buffer_predisable, 118 }; 119 120 int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev) 121 { 122 int ret; 123 struct iio_buffer *buffer; 124 125 /* Allocate a buffer to use - here a kfifo */ 126 buffer = iio_kfifo_allocate(); 127 if (!buffer) { 128 ret = -ENOMEM; 129 goto error_ret; 130 } 131 132 iio_device_attach_buffer(indio_dev, buffer); 133 134 /* Enable timestamps by default */ 135 buffer->scan_timestamp = true; 136 137 /* 138 * Tell the core what device type specific functions should 139 * be run on either side of buffer capture enable / disable. 140 */ 141 indio_dev->setup_ops = &iio_simple_dummy_buffer_setup_ops; 142 143 /* 144 * Configure a polling function. 145 * When a trigger event with this polling function connected 146 * occurs, this function is run. Typically this grabs data 147 * from the device. 148 * 149 * NULL for the bottom half. This is normally implemented only if we 150 * either want to ping a capture now pin (no sleeping) or grab 151 * a timestamp as close as possible to a data ready trigger firing. 152 * 153 * IRQF_ONESHOT ensures irqs are masked such that only one instance 154 * of the handler can run at a time. 155 * 156 * "iio_simple_dummy_consumer%d" formatting string for the irq 'name' 157 * as seen under /proc/interrupts. Remaining parameters as per printk. 158 */ 159 indio_dev->pollfunc = iio_alloc_pollfunc(NULL, 160 &iio_simple_dummy_trigger_h, 161 IRQF_ONESHOT, 162 indio_dev, 163 "iio_simple_dummy_consumer%d", 164 indio_dev->id); 165 166 if (!indio_dev->pollfunc) { 167 ret = -ENOMEM; 168 goto error_free_buffer; 169 } 170 171 /* 172 * Notify the core that this device is capable of buffered capture 173 * driven by a trigger. 174 */ 175 indio_dev->modes |= INDIO_BUFFER_TRIGGERED; 176 177 return 0; 178 179 error_free_buffer: 180 iio_kfifo_free(indio_dev->buffer); 181 error_ret: 182 return ret; 183 } 184 185 /** 186 * iio_simple_dummy_unconfigure_buffer() - release buffer resources 187 * @indo_dev: device instance state 188 */ 189 void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev) 190 { 191 iio_dealloc_pollfunc(indio_dev->pollfunc); 192 iio_kfifo_free(indio_dev->buffer); 193 } 194