2 * CARMA DATA-FPGA Access Driver
4 * Copyright (c) 2009-2011 Ira W. Snyder <iws@ovro.caltech.edu>
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2 of the License, or (at your
9 * option) any later version.
13 * FPGA Memory Dump Format
15 * FPGA #0 control registers (32 x 32-bit words)
16 * FPGA #1 control registers (32 x 32-bit words)
17 * FPGA #2 control registers (32 x 32-bit words)
18 * FPGA #3 control registers (32 x 32-bit words)
19 * SYSFPGA control registers (32 x 32-bit words)
20 * FPGA #0 correlation array (NUM_CORL0 correlation blocks)
21 * FPGA #1 correlation array (NUM_CORL1 correlation blocks)
22 * FPGA #2 correlation array (NUM_CORL2 correlation blocks)
23 * FPGA #3 correlation array (NUM_CORL3 correlation blocks)
25 * Each correlation array consists of:
27 * Correlation Data (2 x NUM_LAGSn x 32-bit words)
28 * Pipeline Metadata (2 x NUM_METAn x 32-bit words)
29 * Quantization Counters (2 x NUM_QCNTn x 32-bit words)
31 * The NUM_CORLn, NUM_LAGSn, NUM_METAn, and NUM_QCNTn values come from
32 * the FPGA configuration registers. They do not change once the FPGA's
33 * have been programmed, they only change on re-programming.
39 * This driver is used to capture correlation spectra off of the four data
40 * processing FPGAs. The FPGAs are often reprogrammed at runtime, therefore
41 * this driver supports dynamic enable/disable of capture while the device
44 * The nominal capture rate is 64Hz (every 15.625ms). To facilitate this fast
45 * capture rate, all buffers are pre-allocated to avoid any potentially long
46 * running memory allocations while capturing.
48 * There are two lists and one pointer which are used to keep track of the
49 * different states of data buffers.
52 * This list holds all empty data buffers which are ready to receive data.
55 * This pointer holds the currently inflight data buffer. This buffer is having
56 * data copied into it by the DMA engine.
59 * This list holds data buffers which have been filled, and are waiting to be
62 * All buffers start life on the free list, then move successively to the
63 * inflight pointer, and then to the used list. After they have been read by
64 * userspace, they are moved back to the free list. The cycle repeats as long
67 * It should be noted that all buffers are mapped and ready for DMA when they
68 * are on any of the three lists. They are only unmapped when they are in the
69 * process of being read by userspace.
73 * Notes on the IRQ masking scheme:
75 * The IRQ masking scheme here is different than most other hardware. The only
76 * way for the DATA-FPGAs to detect if the kernel has taken too long to copy
77 * the data is if the status registers are not cleared before the next
78 * correlation data dump is ready.
80 * The interrupt line is connected to the status registers, such that when they
81 * are cleared, the interrupt is de-asserted. Therein lies our problem. We need
82 * to schedule a long-running DMA operation and return from the interrupt
83 * handler quickly, but we cannot clear the status registers.
85 * To handle this, the system controller FPGA has the capability to connect the
86 * interrupt line to a user-controlled GPIO pin. This pin is driven high
87 * (unasserted) and left that way. To mask the interrupt, we change the
88 * interrupt source to the GPIO pin. Tada, we hid the interrupt. :)
91 #include <linux/of_address.h>
92 #include <linux/of_irq.h>
93 #include <linux/of_platform.h>
94 #include <linux/dma-mapping.h>
95 #include <linux/miscdevice.h>
96 #include <linux/interrupt.h>
97 #include <linux/dmaengine.h>
98 #include <linux/seq_file.h>
99 #include <linux/highmem.h>
100 #include <linux/debugfs.h>
101 #include <linux/kernel.h>
102 #include <linux/module.h>
103 #include <linux/poll.h>
104 #include <linux/slab.h>
105 #include <linux/kref.h>
106 #include <linux/io.h>
108 #include <media/videobuf-dma-sg.h>
110 /* system controller registers */
111 #define SYS_IRQ_SOURCE_CTL 0x24
112 #define SYS_IRQ_OUTPUT_EN 0x28
113 #define SYS_IRQ_OUTPUT_DATA 0x2C
114 #define SYS_IRQ_INPUT_DATA 0x30
115 #define SYS_FPGA_CONFIG_STATUS 0x44
117 /* GPIO IRQ line assignment */
118 #define IRQ_CORL_DONE 0x10
121 #define MMAP_REG_VERSION 0x00
122 #define MMAP_REG_CORL_CONF1 0x08
123 #define MMAP_REG_CORL_CONF2 0x0C
124 #define MMAP_REG_STATUS 0x48
126 #define SYS_FPGA_BLOCK 0xF0000000
128 #define DATA_FPGA_START 0x400000
129 #define DATA_FPGA_SIZE 0x80000
131 static const char drv_name[] = "carma-fpga";
135 #define MIN_DATA_BUFS 8
136 #define MAX_DATA_BUFS 64
139 unsigned int num_lag_ram;
140 unsigned int blk_size;
144 struct list_head entry;
145 struct videobuf_dmabuf vb;
150 /* character device */
151 struct miscdevice miscdev;
155 /* reference count */
158 /* FPGA registers and information */
159 struct fpga_info info[NUM_FPGA];
163 /* FPGA Physical Address/Size Information */
164 resource_size_t phys_addr;
168 struct sg_table corl_table;
169 unsigned int corl_nents;
170 struct dma_chan *chan;
172 /* Protection for all members below */
175 /* Device enable/disable flag */
178 /* Correlation data buffers */
179 wait_queue_head_t wait;
180 struct list_head free;
181 struct list_head used;
182 struct data_buf *inflight;
184 /* Information about data buffers */
185 unsigned int num_dropped;
186 unsigned int num_buffers;
188 struct dentry *dbg_entry;
192 struct fpga_device *priv;
193 struct data_buf *buf;
197 static void fpga_device_release(struct kref *ref)
199 struct fpga_device *priv = container_of(ref, struct fpga_device, ref);
201 /* the last reader has exited, cleanup the last bits */
202 mutex_destroy(&priv->mutex);
207 * Data Buffer Allocation Helpers
211 * data_free_buffer() - free a single data buffer and all allocated memory
212 * @buf: the buffer to free
214 * This will free all of the pages allocated to the given data buffer, and
215 * then free the structure itself
217 static void data_free_buffer(struct data_buf *buf)
219 /* It is ok to free a NULL buffer */
223 /* free all memory */
224 videobuf_dma_free(&buf->vb);
229 * data_alloc_buffer() - allocate and fill a data buffer with pages
230 * @bytes: the number of bytes required
232 * This allocates all space needed for a data buffer. It must be mapped before
233 * use in a DMA transaction using videobuf_dma_map().
235 * Returns NULL on failure
237 static struct data_buf *data_alloc_buffer(const size_t bytes)
239 unsigned int nr_pages;
240 struct data_buf *buf;
243 /* calculate the number of pages necessary */
244 nr_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
246 /* allocate the buffer structure */
247 buf = kzalloc(sizeof(*buf), GFP_KERNEL);
251 /* initialize internal fields */
252 INIT_LIST_HEAD(&buf->entry);
255 /* allocate the videobuf */
256 videobuf_dma_init(&buf->vb);
257 ret = videobuf_dma_init_kernel(&buf->vb, DMA_FROM_DEVICE, nr_pages);
270 * data_free_buffers() - free all allocated buffers
271 * @priv: the driver's private data structure
273 * Free all buffers allocated by the driver (except those currently in the
274 * process of being read by userspace).
276 * LOCKING: must hold dev->mutex
279 static void data_free_buffers(struct fpga_device *priv)
281 struct data_buf *buf, *tmp;
283 /* the device should be stopped, no DMA in progress */
284 BUG_ON(priv->inflight != NULL);
286 list_for_each_entry_safe(buf, tmp, &priv->free, entry) {
287 list_del_init(&buf->entry);
288 videobuf_dma_unmap(priv->dev, &buf->vb);
289 data_free_buffer(buf);
292 list_for_each_entry_safe(buf, tmp, &priv->used, entry) {
293 list_del_init(&buf->entry);
294 videobuf_dma_unmap(priv->dev, &buf->vb);
295 data_free_buffer(buf);
298 priv->num_buffers = 0;
303 * data_alloc_buffers() - allocate 1 seconds worth of data buffers
304 * @priv: the driver's private data structure
306 * Allocate enough buffers for a whole second worth of data
308 * This routine will attempt to degrade nicely by succeeding even if a full
309 * second worth of data buffers could not be allocated, as long as a minimum
310 * number were allocated. In this case, it will print a message to the kernel
313 * The device must not be modifying any lists when this is called.
316 * LOCKING: must hold dev->mutex
318 * Returns 0 on success, -ERRNO otherwise
320 static int data_alloc_buffers(struct fpga_device *priv)
322 struct data_buf *buf;
325 for (i = 0; i < MAX_DATA_BUFS; i++) {
327 /* allocate a buffer */
328 buf = data_alloc_buffer(priv->bufsize);
333 ret = videobuf_dma_map(priv->dev, &buf->vb);
335 data_free_buffer(buf);
339 /* add it to the list of free buffers */
340 list_add_tail(&buf->entry, &priv->free);
344 /* Make sure we allocated the minimum required number of buffers */
345 if (priv->num_buffers < MIN_DATA_BUFS) {
346 dev_err(priv->dev, "Unable to allocate enough data buffers\n");
347 data_free_buffers(priv);
351 /* Warn if we are running in a degraded state, but do not fail */
352 if (priv->num_buffers < MAX_DATA_BUFS) {
354 "Unable to allocate %d buffers, using %d buffers instead\n",
362 * DMA Operations Helpers
366 * fpga_start_addr() - get the physical address a DATA-FPGA
367 * @priv: the driver's private data structure
368 * @fpga: the DATA-FPGA number (zero based)
370 static dma_addr_t fpga_start_addr(struct fpga_device *priv, unsigned int fpga)
372 return priv->phys_addr + 0x400000 + (0x80000 * fpga);
376 * fpga_block_addr() - get the physical address of a correlation data block
377 * @priv: the driver's private data structure
378 * @fpga: the DATA-FPGA number (zero based)
379 * @blknum: the correlation block number (zero based)
381 static dma_addr_t fpga_block_addr(struct fpga_device *priv, unsigned int fpga,
384 return fpga_start_addr(priv, fpga) + (0x10000 * (1 + blknum));
387 #define REG_BLOCK_SIZE (32 * 4)
390 * data_setup_corl_table() - create the scatterlist for correlation dumps
391 * @priv: the driver's private data structure
393 * Create the scatterlist for transferring a correlation dump from the
394 * DATA FPGAs. This structure will be reused for each buffer than needs
395 * to be filled with correlation data.
397 * Returns 0 on success, -ERRNO otherwise
399 static int data_setup_corl_table(struct fpga_device *priv)
401 struct sg_table *table = &priv->corl_table;
402 struct scatterlist *sg;
403 struct fpga_info *info;
406 /* Calculate the number of entries needed */
407 priv->corl_nents = (1 + NUM_FPGA) * REG_BLOCK_SIZE;
408 for (i = 0; i < NUM_FPGA; i++)
409 priv->corl_nents += priv->info[i].num_lag_ram;
411 /* Allocate the scatterlist table */
412 ret = sg_alloc_table(table, priv->corl_nents, GFP_KERNEL);
414 dev_err(priv->dev, "unable to allocate DMA table\n");
418 /* Add the DATA FPGA registers to the scatterlist */
420 for (i = 0; i < NUM_FPGA; i++) {
421 sg_dma_address(sg) = fpga_start_addr(priv, i);
422 sg_dma_len(sg) = REG_BLOCK_SIZE;
426 /* Add the SYS-FPGA registers to the scatterlist */
427 sg_dma_address(sg) = SYS_FPGA_BLOCK;
428 sg_dma_len(sg) = REG_BLOCK_SIZE;
431 /* Add the FPGA correlation data blocks to the scatterlist */
432 for (i = 0; i < NUM_FPGA; i++) {
433 info = &priv->info[i];
434 for (j = 0; j < info->num_lag_ram; j++) {
435 sg_dma_address(sg) = fpga_block_addr(priv, i, j);
436 sg_dma_len(sg) = info->blk_size;
442 * All physical addresses and lengths are present in the structure
443 * now. It can be reused for every FPGA DATA interrupt
449 * FPGA Register Access Helpers
452 static void fpga_write_reg(struct fpga_device *priv, unsigned int fpga,
453 unsigned int reg, u32 val)
455 const int fpga_start = DATA_FPGA_START + (fpga * DATA_FPGA_SIZE);
456 iowrite32be(val, priv->regs + fpga_start + reg);
459 static u32 fpga_read_reg(struct fpga_device *priv, unsigned int fpga,
462 const int fpga_start = DATA_FPGA_START + (fpga * DATA_FPGA_SIZE);
463 return ioread32be(priv->regs + fpga_start + reg);
467 * data_calculate_bufsize() - calculate the data buffer size required
468 * @priv: the driver's private data structure
470 * Calculate the total buffer size needed to hold a single block
471 * of correlation data
475 * Returns 0 on success, -ERRNO otherwise
477 static int data_calculate_bufsize(struct fpga_device *priv)
479 u32 num_corl, num_lags, num_meta, num_qcnt, num_pack;
480 u32 conf1, conf2, version;
481 u32 num_lag_ram, blk_size;
484 /* Each buffer starts with the 5 FPGA register areas */
485 priv->bufsize = (1 + NUM_FPGA) * REG_BLOCK_SIZE;
487 /* Read and store the configuration data for each FPGA */
488 for (i = 0; i < NUM_FPGA; i++) {
489 version = fpga_read_reg(priv, i, MMAP_REG_VERSION);
490 conf1 = fpga_read_reg(priv, i, MMAP_REG_CORL_CONF1);
491 conf2 = fpga_read_reg(priv, i, MMAP_REG_CORL_CONF2);
493 /* minor version 2 and later */
494 if ((version & 0x000000FF) >= 2) {
495 num_corl = (conf1 & 0x000000F0) >> 4;
496 num_pack = (conf1 & 0x00000F00) >> 8;
497 num_lags = (conf1 & 0x00FFF000) >> 12;
498 num_meta = (conf1 & 0x7F000000) >> 24;
499 num_qcnt = (conf2 & 0x00000FFF) >> 0;
501 num_corl = (conf1 & 0x000000F0) >> 4;
502 num_pack = 1; /* implied */
503 num_lags = (conf1 & 0x000FFF00) >> 8;
504 num_meta = (conf1 & 0x7FF00000) >> 20;
505 num_qcnt = (conf2 & 0x00000FFF) >> 0;
508 num_lag_ram = (num_corl + num_pack - 1) / num_pack;
509 blk_size = ((num_pack * num_lags) + num_meta + num_qcnt) * 8;
511 priv->info[i].num_lag_ram = num_lag_ram;
512 priv->info[i].blk_size = blk_size;
513 priv->bufsize += num_lag_ram * blk_size;
515 dev_dbg(priv->dev, "FPGA %d NUM_CORL: %d\n", i, num_corl);
516 dev_dbg(priv->dev, "FPGA %d NUM_PACK: %d\n", i, num_pack);
517 dev_dbg(priv->dev, "FPGA %d NUM_LAGS: %d\n", i, num_lags);
518 dev_dbg(priv->dev, "FPGA %d NUM_META: %d\n", i, num_meta);
519 dev_dbg(priv->dev, "FPGA %d NUM_QCNT: %d\n", i, num_qcnt);
520 dev_dbg(priv->dev, "FPGA %d BLK_SIZE: %d\n", i, blk_size);
523 dev_dbg(priv->dev, "TOTAL BUFFER SIZE: %zu bytes\n", priv->bufsize);
532 * data_disable_interrupts() - stop the device from generating interrupts
533 * @priv: the driver's private data structure
535 * Hide interrupts by switching to GPIO interrupt source
537 * LOCKING: must hold dev->lock
539 static void data_disable_interrupts(struct fpga_device *priv)
541 /* hide the interrupt by switching the IRQ driver to GPIO */
542 iowrite32be(0x2F, priv->regs + SYS_IRQ_SOURCE_CTL);
546 * data_enable_interrupts() - allow the device to generate interrupts
547 * @priv: the driver's private data structure
549 * Unhide interrupts by switching to the FPGA interrupt source. At the
550 * same time, clear the DATA-FPGA status registers.
552 * LOCKING: must hold dev->lock
554 static void data_enable_interrupts(struct fpga_device *priv)
556 /* clear the actual FPGA corl_done interrupt */
557 fpga_write_reg(priv, 0, MMAP_REG_STATUS, 0x0);
558 fpga_write_reg(priv, 1, MMAP_REG_STATUS, 0x0);
559 fpga_write_reg(priv, 2, MMAP_REG_STATUS, 0x0);
560 fpga_write_reg(priv, 3, MMAP_REG_STATUS, 0x0);
562 /* flush the writes */
563 fpga_read_reg(priv, 0, MMAP_REG_STATUS);
564 fpga_read_reg(priv, 1, MMAP_REG_STATUS);
565 fpga_read_reg(priv, 2, MMAP_REG_STATUS);
566 fpga_read_reg(priv, 3, MMAP_REG_STATUS);
568 /* switch back to the external interrupt source */
569 iowrite32be(0x3F, priv->regs + SYS_IRQ_SOURCE_CTL);
573 * data_dma_cb() - DMAEngine callback for DMA completion
574 * @data: the driver's private data structure
576 * Complete a DMA transfer from the DATA-FPGA's
578 * This is called via the DMA callback mechanism, and will handle moving the
579 * completed DMA transaction to the used list, and then wake any processes
580 * waiting for new data
582 * CONTEXT: any, softirq expected
584 static void data_dma_cb(void *data)
586 struct fpga_device *priv = data;
589 spin_lock_irqsave(&priv->lock, flags);
591 /* If there is no inflight buffer, we've got a bug */
592 BUG_ON(priv->inflight == NULL);
594 /* Move the inflight buffer onto the used list */
595 list_move_tail(&priv->inflight->entry, &priv->used);
596 priv->inflight = NULL;
599 * If data dumping is still enabled, then clear the FPGA
600 * status registers and re-enable FPGA interrupts
603 data_enable_interrupts(priv);
605 spin_unlock_irqrestore(&priv->lock, flags);
608 * We've changed both the inflight and used lists, so we need
609 * to wake up any processes that are blocking for those events
611 wake_up(&priv->wait);
615 * data_submit_dma() - prepare and submit the required DMA to fill a buffer
616 * @priv: the driver's private data structure
617 * @buf: the data buffer
619 * Prepare and submit the necessary DMA transactions to fill a correlation
622 * LOCKING: must hold dev->lock
623 * CONTEXT: hardirq only
625 * Returns 0 on success, -ERRNO otherwise
627 static int data_submit_dma(struct fpga_device *priv, struct data_buf *buf)
629 struct scatterlist *dst_sg, *src_sg;
630 unsigned int dst_nents, src_nents;
631 struct dma_chan *chan = priv->chan;
632 struct dma_async_tx_descriptor *tx;
635 unsigned long dma_flags = 0;
637 dst_sg = buf->vb.sglist;
638 dst_nents = buf->vb.sglen;
640 src_sg = priv->corl_table.sgl;
641 src_nents = priv->corl_nents;
644 * All buffers passed to this function should be ready and mapped
645 * for DMA already. Therefore, we don't need to do anything except
646 * submit it to the Freescale DMA Engine for processing
649 /* setup the scatterlist to scatterlist transfer */
650 tx = chan->device->device_prep_dma_sg(chan,
655 dev_err(priv->dev, "unable to prep scatterlist DMA\n");
659 /* submit the transaction to the DMA controller */
660 cookie = tx->tx_submit(tx);
661 if (dma_submit_error(cookie)) {
662 dev_err(priv->dev, "unable to submit scatterlist DMA\n");
666 /* Prepare the re-read of the SYS-FPGA block */
667 dst = sg_dma_address(dst_sg) + (NUM_FPGA * REG_BLOCK_SIZE);
668 src = SYS_FPGA_BLOCK;
669 tx = chan->device->device_prep_dma_memcpy(chan, dst, src,
673 dev_err(priv->dev, "unable to prep SYS-FPGA DMA\n");
677 /* Setup the callback */
678 tx->callback = data_dma_cb;
679 tx->callback_param = priv;
681 /* submit the transaction to the DMA controller */
682 cookie = tx->tx_submit(tx);
683 if (dma_submit_error(cookie)) {
684 dev_err(priv->dev, "unable to submit SYS-FPGA DMA\n");
691 #define CORL_DONE 0x1
694 static irqreturn_t data_irq(int irq, void *dev_id)
696 struct fpga_device *priv = dev_id;
697 bool submitted = false;
698 struct data_buf *buf;
702 /* detect spurious interrupts via FPGA status */
703 for (i = 0; i < 4; i++) {
704 status = fpga_read_reg(priv, i, MMAP_REG_STATUS);
705 if (!(status & (CORL_DONE | CORL_ERR))) {
706 dev_err(priv->dev, "spurious irq detected (FPGA)\n");
711 /* detect spurious interrupts via raw IRQ pin readback */
712 status = ioread32be(priv->regs + SYS_IRQ_INPUT_DATA);
713 if (status & IRQ_CORL_DONE) {
714 dev_err(priv->dev, "spurious irq detected (IRQ)\n");
718 spin_lock(&priv->lock);
721 * This is an error case that should never happen.
723 * If this driver has a bug and manages to re-enable interrupts while
724 * a DMA is in progress, then we will hit this statement and should
725 * start paying attention immediately.
727 BUG_ON(priv->inflight != NULL);
729 /* hide the interrupt by switching the IRQ driver to GPIO */
730 data_disable_interrupts(priv);
732 /* If there are no free buffers, drop this data */
733 if (list_empty(&priv->free)) {
738 buf = list_first_entry(&priv->free, struct data_buf, entry);
739 list_del_init(&buf->entry);
740 BUG_ON(buf->size != priv->bufsize);
742 /* Submit a DMA transfer to get the correlation data */
743 if (data_submit_dma(priv, buf)) {
744 dev_err(priv->dev, "Unable to setup DMA transfer\n");
745 list_move_tail(&buf->entry, &priv->free);
749 /* Save the buffer for the DMA callback */
750 priv->inflight = buf;
753 /* Start the DMA Engine */
754 dma_async_issue_pending(priv->chan);
757 /* If no DMA was submitted, re-enable interrupts */
759 data_enable_interrupts(priv);
761 spin_unlock(&priv->lock);
766 * Realtime Device Enable Helpers
770 * data_device_enable() - enable the device for buffered dumping
771 * @priv: the driver's private data structure
773 * Enable the device for buffered dumping. Allocates buffers and hooks up
774 * the interrupt handler. When this finishes, data will come pouring in.
776 * LOCKING: must hold dev->mutex
777 * CONTEXT: user context only
779 * Returns 0 on success, -ERRNO otherwise
781 static int data_device_enable(struct fpga_device *priv)
787 /* multiple enables are safe: they do nothing */
788 spin_lock_irq(&priv->lock);
789 enabled = priv->enabled;
790 spin_unlock_irq(&priv->lock);
794 /* check that the FPGAs are programmed */
795 val = ioread32be(priv->regs + SYS_FPGA_CONFIG_STATUS);
796 if (!(val & (1 << 18))) {
797 dev_err(priv->dev, "DATA-FPGAs are not enabled\n");
801 /* read the FPGAs to calculate the buffer size */
802 ret = data_calculate_bufsize(priv);
804 dev_err(priv->dev, "unable to calculate buffer size\n");
808 /* allocate the correlation data buffers */
809 ret = data_alloc_buffers(priv);
811 dev_err(priv->dev, "unable to allocate buffers\n");
815 /* setup the source scatterlist for dumping correlation data */
816 ret = data_setup_corl_table(priv);
818 dev_err(priv->dev, "unable to setup correlation DMA table\n");
822 /* prevent the FPGAs from generating interrupts */
823 data_disable_interrupts(priv);
825 /* hookup the irq handler */
826 ret = request_irq(priv->irq, data_irq, IRQF_SHARED, drv_name, priv);
828 dev_err(priv->dev, "unable to request IRQ handler\n");
832 /* allow the DMA callback to re-enable FPGA interrupts */
833 spin_lock_irq(&priv->lock);
834 priv->enabled = true;
835 spin_unlock_irq(&priv->lock);
837 /* allow the FPGAs to generate interrupts */
838 data_enable_interrupts(priv);
842 sg_free_table(&priv->corl_table);
843 priv->corl_nents = 0;
845 data_free_buffers(priv);
850 * data_device_disable() - disable the device for buffered dumping
851 * @priv: the driver's private data structure
853 * Disable the device for buffered dumping. Stops new DMA transactions from
854 * being generated, waits for all outstanding DMA to complete, and then frees
857 * LOCKING: must hold dev->mutex
860 * Returns 0 on success, -ERRNO otherwise
862 static int data_device_disable(struct fpga_device *priv)
864 spin_lock_irq(&priv->lock);
866 /* allow multiple disable */
867 if (!priv->enabled) {
868 spin_unlock_irq(&priv->lock);
873 * Mark the device disabled
875 * This stops DMA callbacks from re-enabling interrupts
877 priv->enabled = false;
879 /* prevent the FPGAs from generating interrupts */
880 data_disable_interrupts(priv);
882 /* wait until all ongoing DMA has finished */
883 while (priv->inflight != NULL) {
884 spin_unlock_irq(&priv->lock);
885 wait_event(priv->wait, priv->inflight == NULL);
886 spin_lock_irq(&priv->lock);
889 spin_unlock_irq(&priv->lock);
891 /* unhook the irq handler */
892 free_irq(priv->irq, priv);
894 /* free the correlation table */
895 sg_free_table(&priv->corl_table);
896 priv->corl_nents = 0;
898 /* free all buffers: the free and used lists are not being changed */
899 data_free_buffers(priv);
906 #ifdef CONFIG_DEBUG_FS
909 * Count the number of entries in the given list
911 static unsigned int list_num_entries(struct list_head *list)
913 struct list_head *entry;
914 unsigned int ret = 0;
916 list_for_each(entry, list)
922 static int data_debug_show(struct seq_file *f, void *offset)
924 struct fpga_device *priv = f->private;
926 spin_lock_irq(&priv->lock);
928 seq_printf(f, "enabled: %d\n", priv->enabled);
929 seq_printf(f, "bufsize: %d\n", priv->bufsize);
930 seq_printf(f, "num_buffers: %d\n", priv->num_buffers);
931 seq_printf(f, "num_free: %d\n", list_num_entries(&priv->free));
932 seq_printf(f, "inflight: %d\n", priv->inflight != NULL);
933 seq_printf(f, "num_used: %d\n", list_num_entries(&priv->used));
934 seq_printf(f, "num_dropped: %d\n", priv->num_dropped);
936 spin_unlock_irq(&priv->lock);
940 static int data_debug_open(struct inode *inode, struct file *file)
942 return single_open(file, data_debug_show, inode->i_private);
945 static const struct file_operations data_debug_fops = {
946 .owner = THIS_MODULE,
947 .open = data_debug_open,
950 .release = single_release,
953 static int data_debugfs_init(struct fpga_device *priv)
955 priv->dbg_entry = debugfs_create_file(drv_name, S_IRUGO, NULL, priv,
957 return PTR_ERR_OR_ZERO(priv->dbg_entry);
960 static void data_debugfs_exit(struct fpga_device *priv)
962 debugfs_remove(priv->dbg_entry);
967 static inline int data_debugfs_init(struct fpga_device *priv)
972 static inline void data_debugfs_exit(struct fpga_device *priv)
976 #endif /* CONFIG_DEBUG_FS */
982 static ssize_t data_en_show(struct device *dev, struct device_attribute *attr,
985 struct fpga_device *priv = dev_get_drvdata(dev);
988 spin_lock_irq(&priv->lock);
989 ret = snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled);
990 spin_unlock_irq(&priv->lock);
995 static ssize_t data_en_set(struct device *dev, struct device_attribute *attr,
996 const char *buf, size_t count)
998 struct fpga_device *priv = dev_get_drvdata(dev);
999 unsigned long enable;
1002 ret = kstrtoul(buf, 0, &enable);
1004 dev_err(priv->dev, "unable to parse enable input\n");
1008 /* protect against concurrent enable/disable */
1009 ret = mutex_lock_interruptible(&priv->mutex);
1014 ret = data_device_enable(priv);
1016 ret = data_device_disable(priv);
1019 dev_err(priv->dev, "device %s failed\n",
1020 enable ? "enable" : "disable");
1026 mutex_unlock(&priv->mutex);
1030 static DEVICE_ATTR(enable, S_IWUSR | S_IRUGO, data_en_show, data_en_set);
1032 static struct attribute *data_sysfs_attrs[] = {
1033 &dev_attr_enable.attr,
1037 static const struct attribute_group rt_sysfs_attr_group = {
1038 .attrs = data_sysfs_attrs,
1042 * FPGA Realtime Data Character Device
1045 static int data_open(struct inode *inode, struct file *filp)
1048 * The miscdevice layer puts our struct miscdevice into the
1049 * filp->private_data field. We use this to find our private
1050 * data and then overwrite it with our own private structure.
1052 struct fpga_device *priv = container_of(filp->private_data,
1053 struct fpga_device, miscdev);
1054 struct fpga_reader *reader;
1057 /* allocate private data */
1058 reader = kzalloc(sizeof(*reader), GFP_KERNEL);
1062 reader->priv = priv;
1065 filp->private_data = reader;
1066 ret = nonseekable_open(inode, filp);
1068 dev_err(priv->dev, "nonseekable-open failed\n");
1074 * success, increase the reference count of the private data structure
1075 * so that it doesn't disappear if the device is unbound
1077 kref_get(&priv->ref);
1081 static int data_release(struct inode *inode, struct file *filp)
1083 struct fpga_reader *reader = filp->private_data;
1084 struct fpga_device *priv = reader->priv;
1086 /* free the per-reader structure */
1087 data_free_buffer(reader->buf);
1089 filp->private_data = NULL;
1091 /* decrement our reference count to the private data */
1092 kref_put(&priv->ref, fpga_device_release);
1096 static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count,
1099 struct fpga_reader *reader = filp->private_data;
1100 struct fpga_device *priv = reader->priv;
1101 struct list_head *used = &priv->used;
1102 bool drop_buffer = false;
1103 struct data_buf *dbuf;
1108 /* check if we already have a partial buffer */
1114 spin_lock_irq(&priv->lock);
1116 /* Block until there is at least one buffer on the used list */
1117 while (list_empty(used)) {
1118 spin_unlock_irq(&priv->lock);
1120 if (filp->f_flags & O_NONBLOCK)
1123 ret = wait_event_interruptible(priv->wait, !list_empty(used));
1127 spin_lock_irq(&priv->lock);
1130 /* Grab the first buffer off of the used list */
1131 dbuf = list_first_entry(used, struct data_buf, entry);
1132 list_del_init(&dbuf->entry);
1134 spin_unlock_irq(&priv->lock);
1136 /* Buffers are always mapped: unmap it */
1137 videobuf_dma_unmap(priv->dev, &dbuf->vb);
1139 /* save the buffer for later */
1141 reader->buf_start = 0;
1144 /* Get the number of bytes available */
1145 avail = dbuf->size - reader->buf_start;
1146 data = dbuf->vb.vaddr + reader->buf_start;
1148 /* Get the number of bytes we can transfer */
1149 count = min(count, avail);
1151 /* Copy the data to the userspace buffer */
1152 if (copy_to_user(ubuf, data, count))
1155 /* Update the amount of available space */
1159 * If there is still some data available, save the buffer for the
1160 * next userspace call to read() and return
1163 reader->buf_start += count;
1169 * Get the buffer ready to be reused for DMA
1171 * If it fails, we pretend that the read never happed and return
1172 * -EFAULT to userspace. The read will be retried.
1174 ret = videobuf_dma_map(priv->dev, &dbuf->vb);
1176 dev_err(priv->dev, "unable to remap buffer for DMA\n");
1180 /* Lock against concurrent enable/disable */
1181 spin_lock_irq(&priv->lock);
1183 /* the reader is finished with this buffer */
1187 * One of two things has happened, the device is disabled, or the
1188 * device has been reconfigured underneath us. In either case, we
1189 * should just throw away the buffer.
1191 * Lockdep complains if this is done under the spinlock, so we
1192 * handle it during the unlock path.
1194 if (!priv->enabled || dbuf->size != priv->bufsize) {
1199 /* The buffer is safe to reuse, so add it back to the free list */
1200 list_add_tail(&dbuf->entry, &priv->free);
1203 spin_unlock_irq(&priv->lock);
1206 videobuf_dma_unmap(priv->dev, &dbuf->vb);
1207 data_free_buffer(dbuf);
1213 static unsigned int data_poll(struct file *filp, struct poll_table_struct *tbl)
1215 struct fpga_reader *reader = filp->private_data;
1216 struct fpga_device *priv = reader->priv;
1217 unsigned int mask = 0;
1219 poll_wait(filp, &priv->wait, tbl);
1221 if (!list_empty(&priv->used))
1222 mask |= POLLIN | POLLRDNORM;
1227 static int data_mmap(struct file *filp, struct vm_area_struct *vma)
1229 struct fpga_reader *reader = filp->private_data;
1230 struct fpga_device *priv = reader->priv;
1231 unsigned long offset, vsize, psize, addr;
1233 /* VMA properties */
1234 offset = vma->vm_pgoff << PAGE_SHIFT;
1235 vsize = vma->vm_end - vma->vm_start;
1236 psize = priv->phys_size - offset;
1237 addr = (priv->phys_addr + offset) >> PAGE_SHIFT;
1239 /* Check against the FPGA region's physical memory size */
1240 if (vsize > psize) {
1241 dev_err(priv->dev, "requested mmap mapping too large\n");
1245 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1247 return io_remap_pfn_range(vma, vma->vm_start, addr, vsize,
1251 static const struct file_operations data_fops = {
1252 .owner = THIS_MODULE,
1254 .release = data_release,
1258 .llseek = no_llseek,
1262 * OpenFirmware Device Subsystem
1265 static bool dma_filter(struct dma_chan *chan, void *data)
1268 * DMA Channel #0 is used for the FPGA Programmer, so ignore it
1270 * This probably won't survive an unload/load cycle of the Freescale
1271 * DMAEngine driver, but that won't be a problem
1273 if (chan->chan_id == 0 && chan->device->dev_id == 0)
1279 static int data_of_probe(struct platform_device *op)
1281 struct device_node *of_node = op->dev.of_node;
1282 struct device *this_device;
1283 struct fpga_device *priv;
1284 struct resource res;
1285 dma_cap_mask_t mask;
1288 /* Allocate private data */
1289 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1291 dev_err(&op->dev, "Unable to allocate device private data\n");
1296 platform_set_drvdata(op, priv);
1297 priv->dev = &op->dev;
1298 kref_init(&priv->ref);
1299 mutex_init(&priv->mutex);
1301 dev_set_drvdata(priv->dev, priv);
1302 spin_lock_init(&priv->lock);
1303 INIT_LIST_HEAD(&priv->free);
1304 INIT_LIST_HEAD(&priv->used);
1305 init_waitqueue_head(&priv->wait);
1307 /* Setup the misc device */
1308 priv->miscdev.minor = MISC_DYNAMIC_MINOR;
1309 priv->miscdev.name = drv_name;
1310 priv->miscdev.fops = &data_fops;
1312 /* Get the physical address of the FPGA registers */
1313 ret = of_address_to_resource(of_node, 0, &res);
1315 dev_err(&op->dev, "Unable to find FPGA physical address\n");
1320 priv->phys_addr = res.start;
1321 priv->phys_size = resource_size(&res);
1323 /* ioremap the registers for use */
1324 priv->regs = of_iomap(of_node, 0);
1326 dev_err(&op->dev, "Unable to ioremap registers\n");
1332 dma_cap_set(DMA_MEMCPY, mask);
1333 dma_cap_set(DMA_INTERRUPT, mask);
1334 dma_cap_set(DMA_SLAVE, mask);
1335 dma_cap_set(DMA_SG, mask);
1337 /* Request a DMA channel */
1338 priv->chan = dma_request_channel(mask, dma_filter, NULL);
1340 dev_err(&op->dev, "Unable to request DMA channel\n");
1342 goto out_unmap_regs;
1345 /* Find the correct IRQ number */
1346 priv->irq = irq_of_parse_and_map(of_node, 0);
1347 if (priv->irq == NO_IRQ) {
1348 dev_err(&op->dev, "Unable to find IRQ line\n");
1350 goto out_release_dma;
1353 /* Drive the GPIO for FPGA IRQ high (no interrupt) */
1354 iowrite32be(IRQ_CORL_DONE, priv->regs + SYS_IRQ_OUTPUT_DATA);
1356 /* Register the miscdevice */
1357 ret = misc_register(&priv->miscdev);
1359 dev_err(&op->dev, "Unable to register miscdevice\n");
1360 goto out_irq_dispose_mapping;
1363 /* Create the debugfs files */
1364 ret = data_debugfs_init(priv);
1366 dev_err(&op->dev, "Unable to create debugfs files\n");
1367 goto out_misc_deregister;
1370 /* Create the sysfs files */
1371 this_device = priv->miscdev.this_device;
1372 dev_set_drvdata(this_device, priv);
1373 ret = sysfs_create_group(&this_device->kobj, &rt_sysfs_attr_group);
1375 dev_err(&op->dev, "Unable to create sysfs files\n");
1376 goto out_data_debugfs_exit;
1379 dev_info(&op->dev, "CARMA FPGA Realtime Data Driver Loaded\n");
1382 out_data_debugfs_exit:
1383 data_debugfs_exit(priv);
1384 out_misc_deregister:
1385 misc_deregister(&priv->miscdev);
1386 out_irq_dispose_mapping:
1387 irq_dispose_mapping(priv->irq);
1389 dma_release_channel(priv->chan);
1391 iounmap(priv->regs);
1393 kref_put(&priv->ref, fpga_device_release);
1398 static int data_of_remove(struct platform_device *op)
1400 struct fpga_device *priv = platform_get_drvdata(op);
1401 struct device *this_device = priv->miscdev.this_device;
1403 /* remove all sysfs files, now the device cannot be re-enabled */
1404 sysfs_remove_group(&this_device->kobj, &rt_sysfs_attr_group);
1406 /* remove all debugfs files */
1407 data_debugfs_exit(priv);
1409 /* disable the device from generating data */
1410 data_device_disable(priv);
1412 /* remove the character device to stop new readers from appearing */
1413 misc_deregister(&priv->miscdev);
1415 /* cleanup everything not needed by readers */
1416 irq_dispose_mapping(priv->irq);
1417 dma_release_channel(priv->chan);
1418 iounmap(priv->regs);
1420 /* release our reference */
1421 kref_put(&priv->ref, fpga_device_release);
1425 static struct of_device_id data_of_match[] = {
1426 { .compatible = "carma,carma-fpga", },
1430 static struct platform_driver data_of_driver = {
1431 .probe = data_of_probe,
1432 .remove = data_of_remove,
1435 .of_match_table = data_of_match,
1439 module_platform_driver(data_of_driver);
1441 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
1442 MODULE_DESCRIPTION("CARMA DATA-FPGA Access Driver");
1443 MODULE_LICENSE("GPL");