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