diff options
Diffstat (limited to 'drivers/misc/carma/carma-fpga.c')
| -rw-r--r-- | drivers/misc/carma/carma-fpga.c | 1507 |
1 files changed, 1507 insertions, 0 deletions
diff --git a/drivers/misc/carma/carma-fpga.c b/drivers/misc/carma/carma-fpga.c new file mode 100644 index 000000000..5aba3fd78 --- /dev/null +++ b/drivers/misc/carma/carma-fpga.c @@ -0,0 +1,1507 @@ +/* + * CARMA DATA-FPGA Access Driver + * + * Copyright (c) 2009-2011 Ira W. Snyder <iws@ovro.caltech.edu> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +/* + * FPGA Memory Dump Format + * + * FPGA #0 control registers (32 x 32-bit words) + * FPGA #1 control registers (32 x 32-bit words) + * FPGA #2 control registers (32 x 32-bit words) + * FPGA #3 control registers (32 x 32-bit words) + * SYSFPGA control registers (32 x 32-bit words) + * FPGA #0 correlation array (NUM_CORL0 correlation blocks) + * FPGA #1 correlation array (NUM_CORL1 correlation blocks) + * FPGA #2 correlation array (NUM_CORL2 correlation blocks) + * FPGA #3 correlation array (NUM_CORL3 correlation blocks) + * + * Each correlation array consists of: + * + * Correlation Data (2 x NUM_LAGSn x 32-bit words) + * Pipeline Metadata (2 x NUM_METAn x 32-bit words) + * Quantization Counters (2 x NUM_QCNTn x 32-bit words) + * + * The NUM_CORLn, NUM_LAGSn, NUM_METAn, and NUM_QCNTn values come from + * the FPGA configuration registers. They do not change once the FPGA's + * have been programmed, they only change on re-programming. + */ + +/* + * Basic Description: + * + * This driver is used to capture correlation spectra off of the four data + * processing FPGAs. The FPGAs are often reprogrammed at runtime, therefore + * this driver supports dynamic enable/disable of capture while the device + * remains open. + * + * The nominal capture rate is 64Hz (every 15.625ms). To facilitate this fast + * capture rate, all buffers are pre-allocated to avoid any potentially long + * running memory allocations while capturing. + * + * There are two lists and one pointer which are used to keep track of the + * different states of data buffers. + * + * 1) free list + * This list holds all empty data buffers which are ready to receive data. + * + * 2) inflight pointer + * This pointer holds the currently inflight data buffer. This buffer is having + * data copied into it by the DMA engine. + * + * 3) used list + * This list holds data buffers which have been filled, and are waiting to be + * read by userspace. + * + * All buffers start life on the free list, then move successively to the + * inflight pointer, and then to the used list. After they have been read by + * userspace, they are moved back to the free list. The cycle repeats as long + * as necessary. + * + * It should be noted that all buffers are mapped and ready for DMA when they + * are on any of the three lists. They are only unmapped when they are in the + * process of being read by userspace. + */ + +/* + * Notes on the IRQ masking scheme: + * + * The IRQ masking scheme here is different than most other hardware. The only + * way for the DATA-FPGAs to detect if the kernel has taken too long to copy + * the data is if the status registers are not cleared before the next + * correlation data dump is ready. + * + * The interrupt line is connected to the status registers, such that when they + * are cleared, the interrupt is de-asserted. Therein lies our problem. We need + * to schedule a long-running DMA operation and return from the interrupt + * handler quickly, but we cannot clear the status registers. + * + * To handle this, the system controller FPGA has the capability to connect the + * interrupt line to a user-controlled GPIO pin. This pin is driven high + * (unasserted) and left that way. To mask the interrupt, we change the + * interrupt source to the GPIO pin. Tada, we hid the interrupt. :) + */ + +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/of_platform.h> +#include <linux/dma-mapping.h> +#include <linux/miscdevice.h> +#include <linux/interrupt.h> +#include <linux/dmaengine.h> +#include <linux/seq_file.h> +#include <linux/highmem.h> +#include <linux/debugfs.h> +#include <linux/vmalloc.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/poll.h> +#include <linux/slab.h> +#include <linux/kref.h> +#include <linux/io.h> + +/* system controller registers */ +#define SYS_IRQ_SOURCE_CTL 0x24 +#define SYS_IRQ_OUTPUT_EN 0x28 +#define SYS_IRQ_OUTPUT_DATA 0x2C +#define SYS_IRQ_INPUT_DATA 0x30 +#define SYS_FPGA_CONFIG_STATUS 0x44 + +/* GPIO IRQ line assignment */ +#define IRQ_CORL_DONE 0x10 + +/* FPGA registers */ +#define MMAP_REG_VERSION 0x00 +#define MMAP_REG_CORL_CONF1 0x08 +#define MMAP_REG_CORL_CONF2 0x0C +#define MMAP_REG_STATUS 0x48 + +#define SYS_FPGA_BLOCK 0xF0000000 + +#define DATA_FPGA_START 0x400000 +#define DATA_FPGA_SIZE 0x80000 + +static const char drv_name[] = "carma-fpga"; + +#define NUM_FPGA 4 + +#define MIN_DATA_BUFS 8 +#define MAX_DATA_BUFS 64 + +struct fpga_info { + unsigned int num_lag_ram; + unsigned int blk_size; +}; + +struct data_buf { + struct list_head entry; + void *vaddr; + struct scatterlist *sglist; + int sglen; + int nr_pages; + size_t size; +}; + +struct fpga_device { + /* character device */ + struct miscdevice miscdev; + struct device *dev; + struct mutex mutex; + + /* reference count */ + struct kref ref; + + /* FPGA registers and information */ + struct fpga_info info[NUM_FPGA]; + void __iomem *regs; + int irq; + + /* FPGA Physical Address/Size Information */ + resource_size_t phys_addr; + size_t phys_size; + + /* DMA structures */ + struct sg_table corl_table; + unsigned int corl_nents; + struct dma_chan *chan; + + /* Protection for all members below */ + spinlock_t lock; + + /* Device enable/disable flag */ + bool enabled; + + /* Correlation data buffers */ + wait_queue_head_t wait; + struct list_head free; + struct list_head used; + struct data_buf *inflight; + + /* Information about data buffers */ + unsigned int num_dropped; + unsigned int num_buffers; + size_t bufsize; + struct dentry *dbg_entry; +}; + +struct fpga_reader { + struct fpga_device *priv; + struct data_buf *buf; + off_t buf_start; +}; + +static void fpga_device_release(struct kref *ref) +{ + struct fpga_device *priv = container_of(ref, struct fpga_device, ref); + + /* the last reader has exited, cleanup the last bits */ + mutex_destroy(&priv->mutex); + kfree(priv); +} + +/* + * Data Buffer Allocation Helpers + */ + +static int carma_dma_init(struct data_buf *buf, int nr_pages) +{ + struct page *pg; + int i; + + buf->vaddr = vmalloc_32(nr_pages << PAGE_SHIFT); + if (NULL == buf->vaddr) { + pr_debug("vmalloc_32(%d pages) failed\n", nr_pages); + return -ENOMEM; + } + + pr_debug("vmalloc is at addr 0x%08lx, size=%d\n", + (unsigned long)buf->vaddr, + nr_pages << PAGE_SHIFT); + + memset(buf->vaddr, 0, nr_pages << PAGE_SHIFT); + buf->nr_pages = nr_pages; + + buf->sglist = vzalloc(buf->nr_pages * sizeof(*buf->sglist)); + if (NULL == buf->sglist) + goto vzalloc_err; + + sg_init_table(buf->sglist, buf->nr_pages); + for (i = 0; i < buf->nr_pages; i++) { + pg = vmalloc_to_page(buf->vaddr + i * PAGE_SIZE); + if (NULL == pg) + goto vmalloc_to_page_err; + sg_set_page(&buf->sglist[i], pg, PAGE_SIZE, 0); + } + return 0; + +vmalloc_to_page_err: + vfree(buf->sglist); + buf->sglist = NULL; +vzalloc_err: + vfree(buf->vaddr); + buf->vaddr = NULL; + return -ENOMEM; +} + +static int carma_dma_map(struct device *dev, struct data_buf *buf) +{ + buf->sglen = dma_map_sg(dev, buf->sglist, + buf->nr_pages, DMA_FROM_DEVICE); + + if (0 == buf->sglen) { + pr_warn("%s: dma_map_sg failed\n", __func__); + return -ENOMEM; + } + return 0; +} + +static int carma_dma_unmap(struct device *dev, struct data_buf *buf) +{ + if (!buf->sglen) + return 0; + + dma_unmap_sg(dev, buf->sglist, buf->sglen, DMA_FROM_DEVICE); + buf->sglen = 0; + return 0; +} + +/** + * data_free_buffer() - free a single data buffer and all allocated memory + * @buf: the buffer to free + * + * This will free all of the pages allocated to the given data buffer, and + * then free the structure itself + */ +static void data_free_buffer(struct data_buf *buf) +{ + /* It is ok to free a NULL buffer */ + if (!buf) + return; + + /* free all memory */ + vfree(buf->sglist); + vfree(buf->vaddr); + kfree(buf); +} + +/** + * data_alloc_buffer() - allocate and fill a data buffer with pages + * @bytes: the number of bytes required + * + * This allocates all space needed for a data buffer. It must be mapped before + * use in a DMA transaction using carma_dma_map(). + * + * Returns NULL on failure + */ +static struct data_buf *data_alloc_buffer(const size_t bytes) +{ + unsigned int nr_pages; + struct data_buf *buf; + int ret; + + /* calculate the number of pages necessary */ + nr_pages = DIV_ROUND_UP(bytes, PAGE_SIZE); + + /* allocate the buffer structure */ + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + goto out_return; + + /* initialize internal fields */ + INIT_LIST_HEAD(&buf->entry); + buf->size = bytes; + + /* allocate the buffer */ + ret = carma_dma_init(buf, nr_pages); + if (ret) + goto out_free_buf; + + return buf; + +out_free_buf: + kfree(buf); +out_return: + return NULL; +} + +/** + * data_free_buffers() - free all allocated buffers + * @priv: the driver's private data structure + * + * Free all buffers allocated by the driver (except those currently in the + * process of being read by userspace). + * + * LOCKING: must hold dev->mutex + * CONTEXT: user + */ +static void data_free_buffers(struct fpga_device *priv) +{ + struct data_buf *buf, *tmp; + + /* the device should be stopped, no DMA in progress */ + BUG_ON(priv->inflight != NULL); + + list_for_each_entry_safe(buf, tmp, &priv->free, entry) { + list_del_init(&buf->entry); + carma_dma_unmap(priv->dev, buf); + data_free_buffer(buf); + } + + list_for_each_entry_safe(buf, tmp, &priv->used, entry) { + list_del_init(&buf->entry); + carma_dma_unmap(priv->dev, buf); + data_free_buffer(buf); + } + + priv->num_buffers = 0; + priv->bufsize = 0; +} + +/** + * data_alloc_buffers() - allocate 1 seconds worth of data buffers + * @priv: the driver's private data structure + * + * Allocate enough buffers for a whole second worth of data + * + * This routine will attempt to degrade nicely by succeeding even if a full + * second worth of data buffers could not be allocated, as long as a minimum + * number were allocated. In this case, it will print a message to the kernel + * log. + * + * The device must not be modifying any lists when this is called. + * + * CONTEXT: user + * LOCKING: must hold dev->mutex + * + * Returns 0 on success, -ERRNO otherwise + */ +static int data_alloc_buffers(struct fpga_device *priv) +{ + struct data_buf *buf; + int i, ret; + + for (i = 0; i < MAX_DATA_BUFS; i++) { + + /* allocate a buffer */ + buf = data_alloc_buffer(priv->bufsize); + if (!buf) + break; + + /* map it for DMA */ + ret = carma_dma_map(priv->dev, buf); + if (ret) { + data_free_buffer(buf); + break; + } + + /* add it to the list of free buffers */ + list_add_tail(&buf->entry, &priv->free); + priv->num_buffers++; + } + + /* Make sure we allocated the minimum required number of buffers */ + if (priv->num_buffers < MIN_DATA_BUFS) { + dev_err(priv->dev, "Unable to allocate enough data buffers\n"); + data_free_buffers(priv); + return -ENOMEM; + } + + /* Warn if we are running in a degraded state, but do not fail */ + if (priv->num_buffers < MAX_DATA_BUFS) { + dev_warn(priv->dev, + "Unable to allocate %d buffers, using %d buffers instead\n", + MAX_DATA_BUFS, i); + } + + return 0; +} + +/* + * DMA Operations Helpers + */ + +/** + * fpga_start_addr() - get the physical address a DATA-FPGA + * @priv: the driver's private data structure + * @fpga: the DATA-FPGA number (zero based) + */ +static dma_addr_t fpga_start_addr(struct fpga_device *priv, unsigned int fpga) +{ + return priv->phys_addr + 0x400000 + (0x80000 * fpga); +} + +/** + * fpga_block_addr() - get the physical address of a correlation data block + * @priv: the driver's private data structure + * @fpga: the DATA-FPGA number (zero based) + * @blknum: the correlation block number (zero based) + */ +static dma_addr_t fpga_block_addr(struct fpga_device *priv, unsigned int fpga, + unsigned int blknum) +{ + return fpga_start_addr(priv, fpga) + (0x10000 * (1 + blknum)); +} + +#define REG_BLOCK_SIZE (32 * 4) + +/** + * data_setup_corl_table() - create the scatterlist for correlation dumps + * @priv: the driver's private data structure + * + * Create the scatterlist for transferring a correlation dump from the + * DATA FPGAs. This structure will be reused for each buffer than needs + * to be filled with correlation data. + * + * Returns 0 on success, -ERRNO otherwise + */ +static int data_setup_corl_table(struct fpga_device *priv) +{ + struct sg_table *table = &priv->corl_table; + struct scatterlist *sg; + struct fpga_info *info; + int i, j, ret; + + /* Calculate the number of entries needed */ + priv->corl_nents = (1 + NUM_FPGA) * REG_BLOCK_SIZE; + for (i = 0; i < NUM_FPGA; i++) + priv->corl_nents += priv->info[i].num_lag_ram; + + /* Allocate the scatterlist table */ + ret = sg_alloc_table(table, priv->corl_nents, GFP_KERNEL); + if (ret) { + dev_err(priv->dev, "unable to allocate DMA table\n"); + return ret; + } + + /* Add the DATA FPGA registers to the scatterlist */ + sg = table->sgl; + for (i = 0; i < NUM_FPGA; i++) { + sg_dma_address(sg) = fpga_start_addr(priv, i); + sg_dma_len(sg) = REG_BLOCK_SIZE; + sg = sg_next(sg); + } + + /* Add the SYS-FPGA registers to the scatterlist */ + sg_dma_address(sg) = SYS_FPGA_BLOCK; + sg_dma_len(sg) = REG_BLOCK_SIZE; + sg = sg_next(sg); + + /* Add the FPGA correlation data blocks to the scatterlist */ + for (i = 0; i < NUM_FPGA; i++) { + info = &priv->info[i]; + for (j = 0; j < info->num_lag_ram; j++) { + sg_dma_address(sg) = fpga_block_addr(priv, i, j); + sg_dma_len(sg) = info->blk_size; + sg = sg_next(sg); + } + } + + /* + * All physical addresses and lengths are present in the structure + * now. It can be reused for every FPGA DATA interrupt + */ + return 0; +} + +/* + * FPGA Register Access Helpers + */ + +static void fpga_write_reg(struct fpga_device *priv, unsigned int fpga, + unsigned int reg, u32 val) +{ + const int fpga_start = DATA_FPGA_START + (fpga * DATA_FPGA_SIZE); + iowrite32be(val, priv->regs + fpga_start + reg); +} + +static u32 fpga_read_reg(struct fpga_device *priv, unsigned int fpga, + unsigned int reg) +{ + const int fpga_start = DATA_FPGA_START + (fpga * DATA_FPGA_SIZE); + return ioread32be(priv->regs + fpga_start + reg); +} + +/** + * data_calculate_bufsize() - calculate the data buffer size required + * @priv: the driver's private data structure + * + * Calculate the total buffer size needed to hold a single block + * of correlation data + * + * CONTEXT: user + * + * Returns 0 on success, -ERRNO otherwise + */ +static int data_calculate_bufsize(struct fpga_device *priv) +{ + u32 num_corl, num_lags, num_meta, num_qcnt, num_pack; + u32 conf1, conf2, version; + u32 num_lag_ram, blk_size; + int i; + + /* Each buffer starts with the 5 FPGA register areas */ + priv->bufsize = (1 + NUM_FPGA) * REG_BLOCK_SIZE; + + /* Read and store the configuration data for each FPGA */ + for (i = 0; i < NUM_FPGA; i++) { + version = fpga_read_reg(priv, i, MMAP_REG_VERSION); + conf1 = fpga_read_reg(priv, i, MMAP_REG_CORL_CONF1); + conf2 = fpga_read_reg(priv, i, MMAP_REG_CORL_CONF2); + + /* minor version 2 and later */ + if ((version & 0x000000FF) >= 2) { + num_corl = (conf1 & 0x000000F0) >> 4; + num_pack = (conf1 & 0x00000F00) >> 8; + num_lags = (conf1 & 0x00FFF000) >> 12; + num_meta = (conf1 & 0x7F000000) >> 24; + num_qcnt = (conf2 & 0x00000FFF) >> 0; + } else { + num_corl = (conf1 & 0x000000F0) >> 4; + num_pack = 1; /* implied */ + num_lags = (conf1 & 0x000FFF00) >> 8; + num_meta = (conf1 & 0x7FF00000) >> 20; + num_qcnt = (conf2 & 0x00000FFF) >> 0; + } + + num_lag_ram = (num_corl + num_pack - 1) / num_pack; + blk_size = ((num_pack * num_lags) + num_meta + num_qcnt) * 8; + + priv->info[i].num_lag_ram = num_lag_ram; + priv->info[i].blk_size = blk_size; + priv->bufsize += num_lag_ram * blk_size; + + dev_dbg(priv->dev, "FPGA %d NUM_CORL: %d\n", i, num_corl); + dev_dbg(priv->dev, "FPGA %d NUM_PACK: %d\n", i, num_pack); + dev_dbg(priv->dev, "FPGA %d NUM_LAGS: %d\n", i, num_lags); + dev_dbg(priv->dev, "FPGA %d NUM_META: %d\n", i, num_meta); + dev_dbg(priv->dev, "FPGA %d NUM_QCNT: %d\n", i, num_qcnt); + dev_dbg(priv->dev, "FPGA %d BLK_SIZE: %d\n", i, blk_size); + } + + dev_dbg(priv->dev, "TOTAL BUFFER SIZE: %zu bytes\n", priv->bufsize); + return 0; +} + +/* + * Interrupt Handling + */ + +/** + * data_disable_interrupts() - stop the device from generating interrupts + * @priv: the driver's private data structure + * + * Hide interrupts by switching to GPIO interrupt source + * + * LOCKING: must hold dev->lock + */ +static void data_disable_interrupts(struct fpga_device *priv) +{ + /* hide the interrupt by switching the IRQ driver to GPIO */ + iowrite32be(0x2F, priv->regs + SYS_IRQ_SOURCE_CTL); +} + +/** + * data_enable_interrupts() - allow the device to generate interrupts + * @priv: the driver's private data structure + * + * Unhide interrupts by switching to the FPGA interrupt source. At the + * same time, clear the DATA-FPGA status registers. + * + * LOCKING: must hold dev->lock + */ +static void data_enable_interrupts(struct fpga_device *priv) +{ + /* clear the actual FPGA corl_done interrupt */ + fpga_write_reg(priv, 0, MMAP_REG_STATUS, 0x0); + fpga_write_reg(priv, 1, MMAP_REG_STATUS, 0x0); + fpga_write_reg(priv, 2, MMAP_REG_STATUS, 0x0); + fpga_write_reg(priv, 3, MMAP_REG_STATUS, 0x0); + + /* flush the writes */ + fpga_read_reg(priv, 0, MMAP_REG_STATUS); + fpga_read_reg(priv, 1, MMAP_REG_STATUS); + fpga_read_reg(priv, 2, MMAP_REG_STATUS); + fpga_read_reg(priv, 3, MMAP_REG_STATUS); + + /* switch back to the external interrupt source */ + iowrite32be(0x3F, priv->regs + SYS_IRQ_SOURCE_CTL); +} + +/** + * data_dma_cb() - DMAEngine callback for DMA completion + * @data: the driver's private data structure + * + * Complete a DMA transfer from the DATA-FPGA's + * + * This is called via the DMA callback mechanism, and will handle moving the + * completed DMA transaction to the used list, and then wake any processes + * waiting for new data + * + * CONTEXT: any, softirq expected + */ +static void data_dma_cb(void *data) +{ + struct fpga_device *priv = data; + unsigned long flags; + + spin_lock_irqsave(&priv->lock, flags); + + /* If there is no inflight buffer, we've got a bug */ + BUG_ON(priv->inflight == NULL); + + /* Move the inflight buffer onto the used list */ + list_move_tail(&priv->inflight->entry, &priv->used); + priv->inflight = NULL; + + /* + * If data dumping is still enabled, then clear the FPGA + * status registers and re-enable FPGA interrupts + */ + if (priv->enabled) + data_enable_interrupts(priv); + + spin_unlock_irqrestore(&priv->lock, flags); + + /* + * We've changed both the inflight and used lists, so we need + * to wake up any processes that are blocking for those events + */ + wake_up(&priv->wait); +} + +/** + * data_submit_dma() - prepare and submit the required DMA to fill a buffer + * @priv: the driver's private data structure + * @buf: the data buffer + * + * Prepare and submit the necessary DMA transactions to fill a correlation + * data buffer. + * + * LOCKING: must hold dev->lock + * CONTEXT: hardirq only + * + * Returns 0 on success, -ERRNO otherwise + */ +static int data_submit_dma(struct fpga_device *priv, struct data_buf *buf) +{ + struct scatterlist *dst_sg, *src_sg; + unsigned int dst_nents, src_nents; + struct dma_chan *chan = priv->chan; + struct dma_async_tx_descriptor *tx; + dma_cookie_t cookie; + dma_addr_t dst, src; + unsigned long dma_flags = 0; + + dst_sg = buf->sglist; + dst_nents = buf->sglen; + + src_sg = priv->corl_table.sgl; + src_nents = priv->corl_nents; + + /* + * All buffers passed to this function should be ready and mapped + * for DMA already. Therefore, we don't need to do anything except + * submit it to the Freescale DMA Engine for processing + */ + + /* setup the scatterlist to scatterlist transfer */ + tx = chan->device->device_prep_dma_sg(chan, + dst_sg, dst_nents, + src_sg, src_nents, + 0); + if (!tx) { + dev_err(priv->dev, "unable to prep scatterlist DMA\n"); + return -ENOMEM; + } + + /* submit the transaction to the DMA controller */ + cookie = tx->tx_submit(tx); + if (dma_submit_error(cookie)) { + dev_err(priv->dev, "unable to submit scatterlist DMA\n"); + return -ENOMEM; + } + + /* Prepare the re-read of the SYS-FPGA block */ + dst = sg_dma_address(dst_sg) + (NUM_FPGA * REG_BLOCK_SIZE); + src = SYS_FPGA_BLOCK; + tx = chan->device->device_prep_dma_memcpy(chan, dst, src, + REG_BLOCK_SIZE, + dma_flags); + if (!tx) { + dev_err(priv->dev, "unable to prep SYS-FPGA DMA\n"); + return -ENOMEM; + } + + /* Setup the callback */ + tx->callback = data_dma_cb; + tx->callback_param = priv; + + /* submit the transaction to the DMA controller */ + cookie = tx->tx_submit(tx); + if (dma_submit_error(cookie)) { + dev_err(priv->dev, "unable to submit SYS-FPGA DMA\n"); + return -ENOMEM; + } + + return 0; +} + +#define CORL_DONE 0x1 +#define CORL_ERR 0x2 + +static irqreturn_t data_irq(int irq, void *dev_id) +{ + struct fpga_device *priv = dev_id; + bool submitted = false; + struct data_buf *buf; + u32 status; + int i; + + /* detect spurious interrupts via FPGA status */ + for (i = 0; i < 4; i++) { + status = fpga_read_reg(priv, i, MMAP_REG_STATUS); + if (!(status & (CORL_DONE | CORL_ERR))) { + dev_err(priv->dev, "spurious irq detected (FPGA)\n"); + return IRQ_NONE; + } + } + + /* detect spurious interrupts via raw IRQ pin readback */ + status = ioread32be(priv->regs + SYS_IRQ_INPUT_DATA); + if (status & IRQ_CORL_DONE) { + dev_err(priv->dev, "spurious irq detected (IRQ)\n"); + return IRQ_NONE; + } + + spin_lock(&priv->lock); + + /* + * This is an error case that should never happen. + * + * If this driver has a bug and manages to re-enable interrupts while + * a DMA is in progress, then we will hit this statement and should + * start paying attention immediately. + */ + BUG_ON(priv->inflight != NULL); + + /* hide the interrupt by switching the IRQ driver to GPIO */ + data_disable_interrupts(priv); + + /* If there are no free buffers, drop this data */ + if (list_empty(&priv->free)) { + priv->num_dropped++; + goto out; + } + + buf = list_first_entry(&priv->free, struct data_buf, entry); + list_del_init(&buf->entry); + BUG_ON(buf->size != priv->bufsize); + + /* Submit a DMA transfer to get the correlation data */ + if (data_submit_dma(priv, buf)) { + dev_err(priv->dev, "Unable to setup DMA transfer\n"); + list_move_tail(&buf->entry, &priv->free); + goto out; + } + + /* Save the buffer for the DMA callback */ + priv->inflight = buf; + submitted = true; + + /* Start the DMA Engine */ + dma_async_issue_pending(priv->chan); + +out: + /* If no DMA was submitted, re-enable interrupts */ + if (!submitted) + data_enable_interrupts(priv); + + spin_unlock(&priv->lock); + return IRQ_HANDLED; +} + +/* + * Realtime Device Enable Helpers + */ + +/** + * data_device_enable() - enable the device for buffered dumping + * @priv: the driver's private data structure + * + * Enable the device for buffered dumping. Allocates buffers and hooks up + * the interrupt handler. When this finishes, data will come pouring in. + * + * LOCKING: must hold dev->mutex + * CONTEXT: user context only + * + * Returns 0 on success, -ERRNO otherwise + */ +static int data_device_enable(struct fpga_device *priv) +{ + bool enabled; + u32 val; + int ret; + + /* multiple enables are safe: they do nothing */ + spin_lock_irq(&priv->lock); + enabled = priv->enabled; + spin_unlock_irq(&priv->lock); + if (enabled) + return 0; + + /* check that the FPGAs are programmed */ + val = ioread32be(priv->regs + SYS_FPGA_CONFIG_STATUS); + if (!(val & (1 << 18))) { + dev_err(priv->dev, "DATA-FPGAs are not enabled\n"); + return -ENODATA; + } + + /* read the FPGAs to calculate the buffer size */ + ret = data_calculate_bufsize(priv); + if (ret) { + dev_err(priv->dev, "unable to calculate buffer size\n"); + goto out_error; + } + + /* allocate the correlation data buffers */ + ret = data_alloc_buffers(priv); + if (ret) { + dev_err(priv->dev, "unable to allocate buffers\n"); + goto out_error; + } + + /* setup the source scatterlist for dumping correlation data */ + ret = data_setup_corl_table(priv); + if (ret) { + dev_err(priv->dev, "unable to setup correlation DMA table\n"); + goto out_error; + } + + /* prevent the FPGAs from generating interrupts */ + data_disable_interrupts(priv); + + /* hookup the irq handler */ + ret = request_irq(priv->irq, data_irq, IRQF_SHARED, drv_name, priv); + if (ret) { + dev_err(priv->dev, "unable to request IRQ handler\n"); + goto out_error; + } + + /* allow the DMA callback to re-enable FPGA interrupts */ + spin_lock_irq(&priv->lock); + priv->enabled = true; + spin_unlock_irq(&priv->lock); + + /* allow the FPGAs to generate interrupts */ + data_enable_interrupts(priv); + return 0; + +out_error: + sg_free_table(&priv->corl_table); + priv->corl_nents = 0; + + data_free_buffers(priv); + return ret; +} + +/** + * data_device_disable() - disable the device for buffered dumping + * @priv: the driver's private data structure + * + * Disable the device for buffered dumping. Stops new DMA transactions from + * being generated, waits for all outstanding DMA to complete, and then frees + * all buffers. + * + * LOCKING: must hold dev->mutex + * CONTEXT: user only + * + * Returns 0 on success, -ERRNO otherwise + */ +static int data_device_disable(struct fpga_device *priv) +{ + spin_lock_irq(&priv->lock); + + /* allow multiple disable */ + if (!priv->enabled) { + spin_unlock_irq(&priv->lock); + return 0; + } + + /* + * Mark the device disabled + * + * This stops DMA callbacks from re-enabling interrupts + */ + priv->enabled = false; + + /* prevent the FPGAs from generating interrupts */ + data_disable_interrupts(priv); + + /* wait until all ongoing DMA has finished */ + while (priv->inflight != NULL) { + spin_unlock_irq(&priv->lock); + wait_event(priv->wait, priv->inflight == NULL); + spin_lock_irq(&priv->lock); + } + + spin_unlock_irq(&priv->lock); + + /* unhook the irq handler */ + free_irq(priv->irq, priv); + + /* free the correlation table */ + sg_free_table(&priv->corl_table); + priv->corl_nents = 0; + + /* free all buffers: the free and used lists are not being changed */ + data_free_buffers(priv); + return 0; +} + +/* + * DEBUGFS Interface + */ +#ifdef CONFIG_DEBUG_FS + +/* + * Count the number of entries in the given list + */ +static unsigned int list_num_entries(struct list_head *list) +{ + struct list_head *entry; + unsigned int ret = 0; + + list_for_each(entry, list) + ret++; + + return ret; +} + +static int data_debug_show(struct seq_file *f, void *offset) +{ + struct fpga_device *priv = f->private; + + spin_lock_irq(&priv->lock); + + seq_printf(f, "enabled: %d\n", priv->enabled); + seq_printf(f, "bufsize: %d\n", priv->bufsize); + seq_printf(f, "num_buffers: %d\n", priv->num_buffers); + seq_printf(f, "num_free: %d\n", list_num_entries(&priv->free)); + seq_printf(f, "inflight: %d\n", priv->inflight != NULL); + seq_printf(f, "num_used: %d\n", list_num_entries(&priv->used)); + seq_printf(f, "num_dropped: %d\n", priv->num_dropped); + + spin_unlock_irq(&priv->lock); + return 0; +} + +static int data_debug_open(struct inode *inode, struct file *file) +{ + return single_open(file, data_debug_show, inode->i_private); +} + +static const struct file_operations data_debug_fops = { + .owner = THIS_MODULE, + .open = data_debug_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static int data_debugfs_init(struct fpga_device *priv) +{ + priv->dbg_entry = debugfs_create_file(drv_name, S_IRUGO, NULL, priv, + &data_debug_fops); + return PTR_ERR_OR_ZERO(priv->dbg_entry); +} + +static void data_debugfs_exit(struct fpga_device *priv) +{ + debugfs_remove(priv->dbg_entry); +} + +#else + +static inline int data_debugfs_init(struct fpga_device *priv) +{ + return 0; +} + +static inline void data_debugfs_exit(struct fpga_device *priv) +{ +} + +#endif /* CONFIG_DEBUG_FS */ + +/* + * SYSFS Attributes + */ + +static ssize_t data_en_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct fpga_device *priv = dev_get_drvdata(dev); + int ret; + + spin_lock_irq(&priv->lock); + ret = snprintf(buf, PAGE_SIZE, "%u\n", priv->enabled); + spin_unlock_irq(&priv->lock); + + return ret; +} + +static ssize_t data_en_set(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct fpga_device *priv = dev_get_drvdata(dev); + unsigned long enable; + int ret; + + ret = kstrtoul(buf, 0, &enable); + if (ret) { + dev_err(priv->dev, "unable to parse enable input\n"); + return ret; + } + + /* protect against concurrent enable/disable */ + ret = mutex_lock_interruptible(&priv->mutex); + if (ret) + return ret; + + if (enable) + ret = data_device_enable(priv); + else + ret = data_device_disable(priv); + + if (ret) { + dev_err(priv->dev, "device %s failed\n", + enable ? "enable" : "disable"); + count = ret; + goto out_unlock; + } + +out_unlock: + mutex_unlock(&priv->mutex); + return count; +} + +static DEVICE_ATTR(enable, S_IWUSR | S_IRUGO, data_en_show, data_en_set); + +static struct attribute *data_sysfs_attrs[] = { + &dev_attr_enable.attr, + NULL, +}; + +static const struct attribute_group rt_sysfs_attr_group = { + .attrs = data_sysfs_attrs, +}; + +/* + * FPGA Realtime Data Character Device + */ + +static int data_open(struct inode *inode, struct file *filp) +{ + /* + * The miscdevice layer puts our struct miscdevice into the + * filp->private_data field. We use this to find our private + * data and then overwrite it with our own private structure. + */ + struct fpga_device *priv = container_of(filp->private_data, + struct fpga_device, miscdev); + struct fpga_reader *reader; + int ret; + + /* allocate private data */ + reader = kzalloc(sizeof(*reader), GFP_KERNEL); + if (!reader) + return -ENOMEM; + + reader->priv = priv; + reader->buf = NULL; + + filp->private_data = reader; + ret = nonseekable_open(inode, filp); + if (ret) { + dev_err(priv->dev, "nonseekable-open failed\n"); + kfree(reader); + return ret; + } + + /* + * success, increase the reference count of the private data structure + * so that it doesn't disappear if the device is unbound + */ + kref_get(&priv->ref); + return 0; +} + +static int data_release(struct inode *inode, struct file *filp) +{ + struct fpga_reader *reader = filp->private_data; + struct fpga_device *priv = reader->priv; + + /* free the per-reader structure */ + data_free_buffer(reader->buf); + kfree(reader); + filp->private_data = NULL; + + /* decrement our reference count to the private data */ + kref_put(&priv->ref, fpga_device_release); + return 0; +} + +static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count, + loff_t *f_pos) +{ + struct fpga_reader *reader = filp->private_data; + struct fpga_device *priv = reader->priv; + struct list_head *used = &priv->used; + bool drop_buffer = false; + struct data_buf *dbuf; + size_t avail; + void *data; + int ret; + + /* check if we already have a partial buffer */ + if (reader->buf) { + dbuf = reader->buf; + goto have_buffer; + } + + spin_lock_irq(&priv->lock); + + /* Block until there is at least one buffer on the used list */ + while (list_empty(used)) { + spin_unlock_irq(&priv->lock); + + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(priv->wait, !list_empty(used)); + if (ret) + return ret; + + spin_lock_irq(&priv->lock); + } + + /* Grab the first buffer off of the used list */ + dbuf = list_first_entry(used, struct data_buf, entry); + list_del_init(&dbuf->entry); + + spin_unlock_irq(&priv->lock); + + /* Buffers are always mapped: unmap it */ + carma_dma_unmap(priv->dev, dbuf); + + /* save the buffer for later */ + reader->buf = dbuf; + reader->buf_start = 0; + +have_buffer: + /* Get the number of bytes available */ + avail = dbuf->size - reader->buf_start; + data = dbuf->vaddr + reader->buf_start; + + /* Get the number of bytes we can transfer */ + count = min(count, avail); + + /* Copy the data to the userspace buffer */ + if (copy_to_user(ubuf, data, count)) + return -EFAULT; + + /* Update the amount of available space */ + avail -= count; + + /* + * If there is still some data available, save the buffer for the + * next userspace call to read() and return + */ + if (avail > 0) { + reader->buf_start += count; + reader->buf = dbuf; + return count; + } + + /* + * Get the buffer ready to be reused for DMA + * + * If it fails, we pretend that the read never happed and return + * -EFAULT to userspace. The read will be retried. + */ + ret = carma_dma_map(priv->dev, dbuf); + if (ret) { + dev_err(priv->dev, "unable to remap buffer for DMA\n"); + return -EFAULT; + } + + /* Lock against concurrent enable/disable */ + spin_lock_irq(&priv->lock); + + /* the reader is finished with this buffer */ + reader->buf = NULL; + + /* + * One of two things has happened, the device is disabled, or the + * device has been reconfigured underneath us. In either case, we + * should just throw away the buffer. + * + * Lockdep complains if this is done under the spinlock, so we + * handle it during the unlock path. + */ + if (!priv->enabled || dbuf->size != priv->bufsize) { + drop_buffer = true; + goto out_unlock; + } + + /* The buffer is safe to reuse, so add it back to the free list */ + list_add_tail(&dbuf->entry, &priv->free); + +out_unlock: + spin_unlock_irq(&priv->lock); + + if (drop_buffer) { + carma_dma_unmap(priv->dev, dbuf); + data_free_buffer(dbuf); + } + + return count; +} + +static unsigned int data_poll(struct file *filp, struct poll_table_struct *tbl) +{ + struct fpga_reader *reader = filp->private_data; + struct fpga_device *priv = reader->priv; + unsigned int mask = 0; + + poll_wait(filp, &priv->wait, tbl); + + if (!list_empty(&priv->used)) + mask |= POLLIN | POLLRDNORM; + + return mask; +} + +static int data_mmap(struct file *filp, struct vm_area_struct *vma) +{ + struct fpga_reader *reader = filp->private_data; + struct fpga_device *priv = reader->priv; + unsigned long offset, vsize, psize, addr; + + /* VMA properties */ + offset = vma->vm_pgoff << PAGE_SHIFT; + vsize = vma->vm_end - vma->vm_start; + psize = priv->phys_size - offset; + addr = (priv->phys_addr + offset) >> PAGE_SHIFT; + + /* Check against the FPGA region's physical memory size */ + if (vsize > psize) { + dev_err(priv->dev, "requested mmap mapping too large\n"); + return -EINVAL; + } + + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); + + return io_remap_pfn_range(vma, vma->vm_start, addr, vsize, + vma->vm_page_prot); +} + +static const struct file_operations data_fops = { + .owner = THIS_MODULE, + .open = data_open, + .release = data_release, + .read = data_read, + .poll = data_poll, + .mmap = data_mmap, + .llseek = no_llseek, +}; + +/* + * OpenFirmware Device Subsystem + */ + +static bool dma_filter(struct dma_chan *chan, void *data) +{ + /* + * DMA Channel #0 is used for the FPGA Programmer, so ignore it + * + * This probably won't survive an unload/load cycle of the Freescale + * DMAEngine driver, but that won't be a problem + */ + if (chan->chan_id == 0 && chan->device->dev_id == 0) + return false; + + return true; +} + +static int data_of_probe(struct platform_device *op) +{ + struct device_node *of_node = op->dev.of_node; + struct device *this_device; + struct fpga_device *priv; + struct resource res; + dma_cap_mask_t mask; + int ret; + + /* Allocate private data */ + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) { + dev_err(&op->dev, "Unable to allocate device private data\n"); + ret = -ENOMEM; + goto out_return; + } + + platform_set_drvdata(op, priv); + priv->dev = &op->dev; + kref_init(&priv->ref); + mutex_init(&priv->mutex); + + dev_set_drvdata(priv->dev, priv); + spin_lock_init(&priv->lock); + INIT_LIST_HEAD(&priv->free); + INIT_LIST_HEAD(&priv->used); + init_waitqueue_head(&priv->wait); + + /* Setup the misc device */ + priv->miscdev.minor = MISC_DYNAMIC_MINOR; + priv->miscdev.name = drv_name; + priv->miscdev.fops = &data_fops; + + /* Get the physical address of the FPGA registers */ + ret = of_address_to_resource(of_node, 0, &res); + if (ret) { + dev_err(&op->dev, "Unable to find FPGA physical address\n"); + ret = -ENODEV; + goto out_free_priv; + } + + priv->phys_addr = res.start; + priv->phys_size = resource_size(&res); + + /* ioremap the registers for use */ + priv->regs = of_iomap(of_node, 0); + if (!priv->regs) { + dev_err(&op->dev, "Unable to ioremap registers\n"); + ret = -ENOMEM; + goto out_free_priv; + } + + dma_cap_zero(mask); + dma_cap_set(DMA_MEMCPY, mask); + dma_cap_set(DMA_INTERRUPT, mask); + dma_cap_set(DMA_SLAVE, mask); + dma_cap_set(DMA_SG, mask); + + /* Request a DMA channel */ + priv->chan = dma_request_channel(mask, dma_filter, NULL); + if (!priv->chan) { + dev_err(&op->dev, "Unable to request DMA channel\n"); + ret = -ENODEV; + goto out_unmap_regs; + } + + /* Find the correct IRQ number */ + priv->irq = irq_of_parse_and_map(of_node, 0); + if (priv->irq == NO_IRQ) { + dev_err(&op->dev, "Unable to find IRQ line\n"); + ret = -ENODEV; + goto out_release_dma; + } + + /* Drive the GPIO for FPGA IRQ high (no interrupt) */ + iowrite32be(IRQ_CORL_DONE, priv->regs + SYS_IRQ_OUTPUT_DATA); + + /* Register the miscdevice */ + ret = misc_register(&priv->miscdev); + if (ret) { + dev_err(&op->dev, "Unable to register miscdevice\n"); + goto out_irq_dispose_mapping; + } + + /* Create the debugfs files */ + ret = data_debugfs_init(priv); + if (ret) { + dev_err(&op->dev, "Unable to create debugfs files\n"); + goto out_misc_deregister; + } + + /* Create the sysfs files */ + this_device = priv->miscdev.this_device; + dev_set_drvdata(this_device, priv); + ret = sysfs_create_group(&this_device->kobj, &rt_sysfs_attr_group); + if (ret) { + dev_err(&op->dev, "Unable to create sysfs files\n"); + goto out_data_debugfs_exit; + } + + dev_info(&op->dev, "CARMA FPGA Realtime Data Driver Loaded\n"); + return 0; + +out_data_debugfs_exit: + data_debugfs_exit(priv); +out_misc_deregister: + misc_deregister(&priv->miscdev); +out_irq_dispose_mapping: + irq_dispose_mapping(priv->irq); +out_release_dma: + dma_release_channel(priv->chan); +out_unmap_regs: + iounmap(priv->regs); +out_free_priv: + kref_put(&priv->ref, fpga_device_release); +out_return: + return ret; +} + +static int data_of_remove(struct platform_device *op) +{ + struct fpga_device *priv = platform_get_drvdata(op); + struct device *this_device = priv->miscdev.this_device; + + /* remove all sysfs files, now the device cannot be re-enabled */ + sysfs_remove_group(&this_device->kobj, &rt_sysfs_attr_group); + + /* remove all debugfs files */ + data_debugfs_exit(priv); + + /* disable the device from generating data */ + data_device_disable(priv); + + /* remove the character device to stop new readers from appearing */ + misc_deregister(&priv->miscdev); + + /* cleanup everything not needed by readers */ + irq_dispose_mapping(priv->irq); + dma_release_channel(priv->chan); + iounmap(priv->regs); + + /* release our reference */ + kref_put(&priv->ref, fpga_device_release); + return 0; +} + +static const struct of_device_id data_of_match[] = { + { .compatible = "carma,carma-fpga", }, + {}, +}; + +static struct platform_driver data_of_driver = { + .probe = data_of_probe, + .remove = data_of_remove, + .driver = { + .name = drv_name, + .of_match_table = data_of_match, + }, +}; + +module_platform_driver(data_of_driver); + +MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); +MODULE_DESCRIPTION("CARMA DATA-FPGA Access Driver"); +MODULE_LICENSE("GPL"); |