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/buffer.h> 24 #include <linux/iio/kfifo_buf.h> 25 26 #include "iio_simple_dummy.h" 27 28 /* Some fake data */ 29 30 static const s16 fakedata[] = { 31 [DUMMY_INDEX_VOLTAGE_0] = 7, 32 [DUMMY_INDEX_DIFFVOLTAGE_1M2] = -33, 33 [DUMMY_INDEX_DIFFVOLTAGE_3M4] = -2, 34 [DUMMY_INDEX_ACCELX] = 344, 35 }; 36 37 /** 38 * iio_simple_dummy_trigger_h() - the trigger handler function 39 * @irq: the interrupt number 40 * @p: private data - always a pointer to the poll func. 41 * 42 * This is the guts of buffered capture. On a trigger event occurring, 43 * if the pollfunc is attached then this handler is called as a threaded 44 * interrupt (and hence may sleep). It is responsible for grabbing data 45 * from the device and pushing it into the associated buffer. 46 */ 47 static irqreturn_t iio_simple_dummy_trigger_h(int irq, void *p) 48 { 49 struct iio_poll_func *pf = p; 50 struct iio_dev *indio_dev = pf->indio_dev; 51 int len = 0; 52 u16 *data; 53 54 data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL); 55 if (!data) 56 goto done; 57 58 if (!bitmap_empty(indio_dev->active_scan_mask, indio_dev->masklength)) { 59 /* 60 * Three common options here: 61 * hardware scans: certain combinations of channels make 62 * up a fast read. The capture will consist of all of them. 63 * Hence we just call the grab data function and fill the 64 * buffer without processing. 65 * software scans: can be considered to be random access 66 * so efficient reading is just a case of minimal bus 67 * transactions. 68 * software culled hardware scans: 69 * occasionally a driver may process the nearest hardware 70 * scan to avoid storing elements that are not desired. This 71 * is the fiddliest option by far. 72 * Here let's pretend we have random access. And the values are 73 * in the constant table fakedata. 74 */ 75 int i, j; 76 77 for (i = 0, j = 0; 78 i < bitmap_weight(indio_dev->active_scan_mask, 79 indio_dev->masklength); 80 i++, j++) { 81 j = find_next_bit(indio_dev->active_scan_mask, 82 indio_dev->masklength, j); 83 /* random access read from the 'device' */ 84 data[i] = fakedata[j]; 85 len += 2; 86 } 87 } 88 89 iio_push_to_buffers_with_timestamp(indio_dev, data, 90 iio_get_time_ns(indio_dev)); 91 92 kfree(data); 93 94 done: 95 /* 96 * Tell the core we are done with this trigger and ready for the 97 * next one. 98 */ 99 iio_trigger_notify_done(indio_dev->trig); 100 101 return IRQ_HANDLED; 102 } 103 104 static const struct iio_buffer_setup_ops iio_simple_dummy_buffer_setup_ops = { 105 /* 106 * iio_triggered_buffer_postenable: 107 * Generic function that simply attaches the pollfunc to the trigger. 108 * Replace this to mess with hardware state before we attach the 109 * trigger. 110 */ 111 .postenable = &iio_triggered_buffer_postenable, 112 /* 113 * iio_triggered_buffer_predisable: 114 * Generic function that simple detaches the pollfunc from the trigger. 115 * Replace this to put hardware state back again after the trigger is 116 * detached but before userspace knows we have disabled the ring. 117 */ 118 .predisable = &iio_triggered_buffer_predisable, 119 }; 120 121 int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev) 122 { 123 int ret; 124 struct iio_buffer *buffer; 125 126 /* Allocate a buffer to use - here a kfifo */ 127 buffer = iio_kfifo_allocate(); 128 if (!buffer) { 129 ret = -ENOMEM; 130 goto error_ret; 131 } 132 133 iio_device_attach_buffer(indio_dev, buffer); 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; 176 177 error_free_buffer: 178 iio_kfifo_free(indio_dev->buffer); 179 error_ret: 180 return ret; 181 } 182 183 /** 184 * iio_simple_dummy_unconfigure_buffer() - release buffer resources 185 * @indo_dev: device instance state 186 */ 187 void iio_simple_dummy_unconfigure_buffer(struct iio_dev *indio_dev) 188 { 189 iio_dealloc_pollfunc(indio_dev->pollfunc); 190 iio_kfifo_free(indio_dev->buffer); 191 } 192