gro: Allow tunnel stacking in the case of FOU/GUE

[linux/fpc-iii.git] / drivers / misc / carma / carma-fpga-program.c

/*
 * CARMA Board DATA-FPGA Programmer
 *
 * 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.
 */

#include <linux/dma-mapping.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/completion.h>
#include <linux/miscdevice.h>
#include <linux/dmaengine.h>
#include <linux/fsldma.h>
#include <linux/interrupt.h>
#include <linux/highmem.h>
#include <linux/vmalloc.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include <linux/kref.h>
#include <linux/fs.h>
#include <linux/io.h>

/* MPC8349EMDS specific get_immrbase() */
#include <sysdev/fsl_soc.h>

static const char drv_name[] = "carma-fpga-program";

/*
 * Firmware images are always this exact size
 *
 * 12849552 bytes for a CARMA Digitizer Board (EP2S90 FPGAs)
 * 18662880 bytes for a CARMA Correlator Board (EP2S130 FPGAs)
 */
#define FW_SIZE_EP2S90          12849552
#define FW_SIZE_EP2S130         18662880

struct fpga_dev {
        struct miscdevice miscdev;

        /* Reference count */
        struct kref ref;

        /* Device Registers */
        struct device *dev;
        void __iomem *regs;
        void __iomem *immr;

        /* Freescale DMA Device */
        struct dma_chan *chan;

        /* Interrupts */
        int irq, status;
        struct completion completion;

        /* FPGA Bitfile */
        struct mutex lock;

        void *vaddr;
        struct scatterlist *sglist;
        int sglen;
        int nr_pages;
        bool buf_allocated;

        /* max size and written bytes */
        size_t fw_size;
        size_t bytes;
};

static int fpga_dma_init(struct fpga_dev *priv, int nr_pages)
{
        struct page *pg;
        int i;

        priv->vaddr = vmalloc_32(nr_pages << PAGE_SHIFT);
        if (NULL == priv->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)priv->vaddr,
                                nr_pages << PAGE_SHIFT);

        memset(priv->vaddr, 0, nr_pages << PAGE_SHIFT);
        priv->nr_pages = nr_pages;

        priv->sglist = vzalloc(priv->nr_pages * sizeof(*priv->sglist));
        if (NULL == priv->sglist)
                goto vzalloc_err;

        sg_init_table(priv->sglist, priv->nr_pages);
        for (i = 0; i < priv->nr_pages; i++) {
                pg = vmalloc_to_page(priv->vaddr + i * PAGE_SIZE);
                if (NULL == pg)
                        goto vmalloc_to_page_err;
                sg_set_page(&priv->sglist[i], pg, PAGE_SIZE, 0);
        }
        return 0;

vmalloc_to_page_err:
        vfree(priv->sglist);
        priv->sglist = NULL;
vzalloc_err:
        vfree(priv->vaddr);
        priv->vaddr = NULL;
        return -ENOMEM;
}

static int fpga_dma_map(struct fpga_dev *priv)
{
        priv->sglen = dma_map_sg(priv->dev, priv->sglist,
                        priv->nr_pages, DMA_TO_DEVICE);

        if (0 == priv->sglen) {
                pr_warn("%s: dma_map_sg failed\n", __func__);
                return -ENOMEM;
        }
        return 0;
}

static int fpga_dma_unmap(struct fpga_dev *priv)
{
        if (!priv->sglen)
                return 0;

        dma_unmap_sg(priv->dev, priv->sglist, priv->sglen, DMA_TO_DEVICE);
        priv->sglen = 0;
        return 0;
}

/*
 * FPGA Bitfile Helpers
 */

/**
 * fpga_drop_firmware_data() - drop the bitfile image from memory
 * @priv: the driver's private data structure
 *
 * LOCKING: must hold priv->lock
 */
static void fpga_drop_firmware_data(struct fpga_dev *priv)
{
        vfree(priv->sglist);
        vfree(priv->vaddr);
        priv->buf_allocated = false;
        priv->bytes = 0;
}

/*
 * Private Data Reference Count
 */

static void fpga_dev_remove(struct kref *ref)
{
        struct fpga_dev *priv = container_of(ref, struct fpga_dev, ref);

        /* free any firmware image that was not programmed */
        fpga_drop_firmware_data(priv);

        mutex_destroy(&priv->lock);
        kfree(priv);
}

/*
 * LED Trigger (could be a seperate module)
 */

/*
 * NOTE: this whole thing does have the problem that whenever the led's are
 * NOTE: first set to use the fpga trigger, they could be in the wrong state
 */

DEFINE_LED_TRIGGER(ledtrig_fpga);

static void ledtrig_fpga_programmed(bool enabled)
{
        if (enabled)
                led_trigger_event(ledtrig_fpga, LED_FULL);
        else
                led_trigger_event(ledtrig_fpga, LED_OFF);
}

/*
 * FPGA Register Helpers
 */

/* Register Definitions */
#define FPGA_CONFIG_CONTROL             0x40
#define FPGA_CONFIG_STATUS              0x44
#define FPGA_CONFIG_FIFO_SIZE           0x48
#define FPGA_CONFIG_FIFO_USED           0x4C
#define FPGA_CONFIG_TOTAL_BYTE_COUNT    0x50
#define FPGA_CONFIG_CUR_BYTE_COUNT      0x54

#define FPGA_FIFO_ADDRESS               0x3000

static int fpga_fifo_size(void __iomem *regs)
{
        return ioread32be(regs + FPGA_CONFIG_FIFO_SIZE);
}

#define CFG_STATUS_ERR_MASK     0xfffe

static int fpga_config_error(void __iomem *regs)
{
        return ioread32be(regs + FPGA_CONFIG_STATUS) & CFG_STATUS_ERR_MASK;
}

static int fpga_fifo_empty(void __iomem *regs)
{
        return ioread32be(regs + FPGA_CONFIG_FIFO_USED) == 0;
}

static void fpga_fifo_write(void __iomem *regs, u32 val)
{
        iowrite32be(val, regs + FPGA_FIFO_ADDRESS);
}

static void fpga_set_byte_count(void __iomem *regs, u32 count)
{
        iowrite32be(count, regs + FPGA_CONFIG_TOTAL_BYTE_COUNT);
}

#define CFG_CTL_ENABLE  (1 << 0)
#define CFG_CTL_RESET   (1 << 1)
#define CFG_CTL_DMA     (1 << 2)

static void fpga_programmer_enable(struct fpga_dev *priv, bool dma)
{
        u32 val;

        val = (dma) ? (CFG_CTL_ENABLE | CFG_CTL_DMA) : CFG_CTL_ENABLE;
        iowrite32be(val, priv->regs + FPGA_CONFIG_CONTROL);
}

static void fpga_programmer_disable(struct fpga_dev *priv)
{
        iowrite32be(0x0, priv->regs + FPGA_CONFIG_CONTROL);
}

static void fpga_dump_registers(struct fpga_dev *priv)
{
        u32 control, status, size, used, total, curr;

        /* good status: do nothing */
        if (priv->status == 0)
                return;

        /* Dump all status registers */
        control = ioread32be(priv->regs + FPGA_CONFIG_CONTROL);
        status = ioread32be(priv->regs + FPGA_CONFIG_STATUS);
        size = ioread32be(priv->regs + FPGA_CONFIG_FIFO_SIZE);
        used = ioread32be(priv->regs + FPGA_CONFIG_FIFO_USED);
        total = ioread32be(priv->regs + FPGA_CONFIG_TOTAL_BYTE_COUNT);
        curr = ioread32be(priv->regs + FPGA_CONFIG_CUR_BYTE_COUNT);

        dev_err(priv->dev, "Configuration failed, dumping status registers\n");
        dev_err(priv->dev, "Control:    0x%.8x\n", control);
        dev_err(priv->dev, "Status:     0x%.8x\n", status);
        dev_err(priv->dev, "FIFO Size:  0x%.8x\n", size);
        dev_err(priv->dev, "FIFO Used:  0x%.8x\n", used);
        dev_err(priv->dev, "FIFO Total: 0x%.8x\n", total);
        dev_err(priv->dev, "FIFO Curr:  0x%.8x\n", curr);
}

/*
 * FPGA Power Supply Code
 */

#define CTL_PWR_CONTROL         0x2006
#define CTL_PWR_STATUS          0x200A
#define CTL_PWR_FAIL            0x200B

#define PWR_CONTROL_ENABLE      0x01

#define PWR_STATUS_ERROR_MASK   0x10
#define PWR_STATUS_GOOD         0x0f

/*
 * Determine if the FPGA power is good for all supplies
 */
static bool fpga_power_good(struct fpga_dev *priv)
{
        u8 val;

        val = ioread8(priv->regs + CTL_PWR_STATUS);
        if (val & PWR_STATUS_ERROR_MASK)
                return false;

        return val == PWR_STATUS_GOOD;
}

/*
 * Disable the FPGA power supplies
 */
static void fpga_disable_power_supplies(struct fpga_dev *priv)
{
        unsigned long start;
        u8 val;

        iowrite8(0x0, priv->regs + CTL_PWR_CONTROL);

        /*
         * Wait 500ms for the power rails to discharge
         *
         * Without this delay, the CTL-CPLD state machine can get into a
         * state where it is waiting for the power-goods to assert, but they
         * never do. This only happens when enabling and disabling the
         * power sequencer very rapidly.
         *
         * The loop below will also wait for the power goods to de-assert,
         * but testing has shown that they are always disabled by the time
         * the sleep completes. However, omitting the sleep and only waiting
         * for the power-goods to de-assert was not sufficient to ensure
         * that the power sequencer would not wedge itself.
         */
        msleep(500);

        start = jiffies;
        while (time_before(jiffies, start + HZ)) {
                val = ioread8(priv->regs + CTL_PWR_STATUS);
                if (!(val & PWR_STATUS_GOOD))
                        break;

                usleep_range(5000, 10000);
        }

        val = ioread8(priv->regs + CTL_PWR_STATUS);
        if (val & PWR_STATUS_GOOD) {
                dev_err(priv->dev, "power disable failed: "
                                   "power goods: status 0x%.2x\n", val);
        }

        if (val & PWR_STATUS_ERROR_MASK) {
                dev_err(priv->dev, "power disable failed: "
                                   "alarm bit set: status 0x%.2x\n", val);
        }
}

/**
 * fpga_enable_power_supplies() - enable the DATA-FPGA power supplies
 * @priv: the driver's private data structure
 *
 * Enable the DATA-FPGA power supplies, waiting up to 1 second for
 * them to enable successfully.
 *
 * Returns 0 on success, -ERRNO otherwise
 */
static int fpga_enable_power_supplies(struct fpga_dev *priv)
{
        unsigned long start = jiffies;

        if (fpga_power_good(priv)) {
                dev_dbg(priv->dev, "power was already good\n");
                return 0;
        }

        iowrite8(PWR_CONTROL_ENABLE, priv->regs + CTL_PWR_CONTROL);
        while (time_before(jiffies, start + HZ)) {
                if (fpga_power_good(priv))
                        return 0;

                usleep_range(5000, 10000);
        }

        return fpga_power_good(priv) ? 0 : -ETIMEDOUT;
}

/*
 * Determine if the FPGA power supplies are all enabled
 */
static bool fpga_power_enabled(struct fpga_dev *priv)
{
        u8 val;

        val = ioread8(priv->regs + CTL_PWR_CONTROL);
        if (val & PWR_CONTROL_ENABLE)
                return true;

        return false;
}

/*
 * Determine if the FPGA's are programmed and running correctly
 */
static bool fpga_running(struct fpga_dev *priv)
{
        if (!fpga_power_good(priv))
                return false;

        /* Check the config done bit */
        return ioread32be(priv->regs + FPGA_CONFIG_STATUS) & (1 << 18);
}

/*
 * FPGA Programming Code
 */

/**
 * fpga_program_block() - put a block of data into the programmer's FIFO
 * @priv: the driver's private data structure
 * @buf: the data to program
 * @count: the length of data to program (must be a multiple of 4 bytes)
 *
 * Returns 0 on success, -ERRNO otherwise
 */
static int fpga_program_block(struct fpga_dev *priv, void *buf, size_t count)
{
        u32 *data = buf;
        int size = fpga_fifo_size(priv->regs);
        int i, len;
        unsigned long timeout;

        /* enforce correct data length for the FIFO */
        BUG_ON(count % 4 != 0);

        while (count > 0) {

                /* Get the size of the block to write (maximum is FIFO_SIZE) */
                len = min_t(size_t, count, size);
                timeout = jiffies + HZ / 4;

                /* Write the block */
                for (i = 0; i < len / 4; i++)
                        fpga_fifo_write(priv->regs, data[i]);

                /* Update the amounts left */
                count -= len;
                data += len / 4;

                /* Wait for the fifo to empty */
                while (true) {

                        if (fpga_fifo_empty(priv->regs)) {
                                break;
                        } else {
                                dev_dbg(priv->dev, "Fifo not empty\n");
                                cpu_relax();
                        }

                        if (fpga_config_error(priv->regs)) {
                                dev_err(priv->dev, "Error detected\n");
                                return -EIO;
                        }

                        if (time_after(jiffies, timeout)) {
                                dev_err(priv->dev, "Fifo drain timeout\n");
                                return -ETIMEDOUT;
                        }

                        usleep_range(5000, 10000);
                }
        }

        return 0;
}

/**
 * fpga_program_cpu() - program the DATA-FPGA's using the CPU
 * @priv: the driver's private data structure
 *
 * This is useful when the DMA programming method fails. It is possible to
 * wedge the Freescale DMA controller such that the DMA programming method
 * always fails. This method has always succeeded.
 *
 * Returns 0 on success, -ERRNO otherwise
 */
static noinline int fpga_program_cpu(struct fpga_dev *priv)
{
        int ret;
        unsigned long timeout;

        /* Disable the programmer */
        fpga_programmer_disable(priv);

        /* Set the total byte count */
        fpga_set_byte_count(priv->regs, priv->bytes);
        dev_dbg(priv->dev, "total byte count %u bytes\n", priv->bytes);

        /* Enable the controller for programming */
        fpga_programmer_enable(priv, false);
        dev_dbg(priv->dev, "enabled the controller\n");

        /* Write each chunk of the FPGA bitfile to FPGA programmer */
        ret = fpga_program_block(priv, priv->vaddr, priv->bytes);
        if (ret)
                goto out_disable_controller;

        /* Wait for the interrupt handler to signal that programming finished */
        timeout = wait_for_completion_timeout(&priv->completion, 2 * HZ);
        if (!timeout) {
                dev_err(priv->dev, "Timed out waiting for completion\n");
                ret = -ETIMEDOUT;
                goto out_disable_controller;
        }

        /* Retrieve the status from the interrupt handler */
        ret = priv->status;

out_disable_controller:
        fpga_programmer_disable(priv);
        return ret;
}

#define FIFO_DMA_ADDRESS        0xf0003000
#define FIFO_MAX_LEN            4096

/**
 * fpga_program_dma() - program the DATA-FPGA's using the DMA engine
 * @priv: the driver's private data structure
 *
 * Program the DATA-FPGA's using the Freescale DMA engine. This requires that
 * the engine is programmed such that the hardware DMA request lines can
 * control the entire DMA transaction. The system controller FPGA then
 * completely offloads the programming from the CPU.
 *
 * Returns 0 on success, -ERRNO otherwise
 */
static noinline int fpga_program_dma(struct fpga_dev *priv)
{
        struct dma_chan *chan = priv->chan;
        struct dma_async_tx_descriptor *tx;
        size_t num_pages, len, avail = 0;
        struct dma_slave_config config;
        struct scatterlist *sg;
        struct sg_table table;
        dma_cookie_t cookie;
        int ret, i;
        unsigned long timeout;

        /* Disable the programmer */
        fpga_programmer_disable(priv);

        /* Allocate a scatterlist for the DMA destination */
        num_pages = DIV_ROUND_UP(priv->bytes, FIFO_MAX_LEN);
        ret = sg_alloc_table(&table, num_pages, GFP_KERNEL);
        if (ret) {
                dev_err(priv->dev, "Unable to allocate dst scatterlist\n");
                ret = -ENOMEM;
                goto out_return;
        }

        /*
         * This is an ugly hack
         *
         * We fill in a scatterlist as if it were mapped for DMA. This is
         * necessary because there exists no better structure for this
         * inside the kernel code.
         *
         * As an added bonus, we can use the DMAEngine API for all of this,
         * rather than inventing another extremely similar API.
         */
        avail = priv->bytes;
        for_each_sg(table.sgl, sg, num_pages, i) {
                len = min_t(size_t, avail, FIFO_MAX_LEN);
                sg_dma_address(sg) = FIFO_DMA_ADDRESS;
                sg_dma_len(sg) = len;

                avail -= len;
        }

        /* Map the buffer for DMA */
        ret = fpga_dma_map(priv);
        if (ret) {
                dev_err(priv->dev, "Unable to map buffer for DMA\n");
                goto out_free_table;
        }

        /*
         * Configure the DMA channel to transfer FIFO_SIZE / 2 bytes per
         * transaction, and then put it under external control
         */
        memset(&config, 0, sizeof(config));
        config.direction = DMA_MEM_TO_DEV;
        config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
        config.dst_maxburst = fpga_fifo_size(priv->regs) / 2 / 4;
        ret = dmaengine_slave_config(chan, &config);
        if (ret) {
                dev_err(priv->dev, "DMA slave configuration failed\n");
                goto out_dma_unmap;
        }

        ret = fsl_dma_external_start(chan, 1);
        if (ret) {
                dev_err(priv->dev, "DMA external control setup failed\n");
                goto out_dma_unmap;
        }

        /* setup and submit the DMA transaction */

        tx = dmaengine_prep_dma_sg(chan, table.sgl, num_pages,
                        priv->sglist, priv->sglen, 0);
        if (!tx) {
                dev_err(priv->dev, "Unable to prep DMA transaction\n");
                ret = -ENOMEM;
                goto out_dma_unmap;
        }

        cookie = tx->tx_submit(tx);
        if (dma_submit_error(cookie)) {
                dev_err(priv->dev, "Unable to submit DMA transaction\n");
                ret = -ENOMEM;
                goto out_dma_unmap;
        }

        dma_async_issue_pending(chan);

        /* Set the total byte count */
        fpga_set_byte_count(priv->regs, priv->bytes);
        dev_dbg(priv->dev, "total byte count %u bytes\n", priv->bytes);

        /* Enable the controller for DMA programming */
        fpga_programmer_enable(priv, true);
        dev_dbg(priv->dev, "enabled the controller\n");

        /* Wait for the interrupt handler to signal that programming finished */
        timeout = wait_for_completion_timeout(&priv->completion, 2 * HZ);
        if (!timeout) {
                dev_err(priv->dev, "Timed out waiting for completion\n");
                ret = -ETIMEDOUT;
                goto out_disable_controller;
        }

        /* Retrieve the status from the interrupt handler */
        ret = priv->status;

out_disable_controller:
        fpga_programmer_disable(priv);
out_dma_unmap:
        fpga_dma_unmap(priv);
out_free_table:
        sg_free_table(&table);
out_return:
        return ret;
}

/*
 * Interrupt Handling
 */

static irqreturn_t fpga_irq(int irq, void *dev_id)
{
        struct fpga_dev *priv = dev_id;

        /* Save the status */
        priv->status = fpga_config_error(priv->regs) ? -EIO : 0;
        dev_dbg(priv->dev, "INTERRUPT status %d\n", priv->status);
        fpga_dump_registers(priv);

        /* Disabling the programmer clears the interrupt */
        fpga_programmer_disable(priv);

        /* Notify any waiters */
        complete(&priv->completion);

        return IRQ_HANDLED;
}

/*
 * SYSFS Helpers
 */

/**
 * fpga_do_stop() - deconfigure (reset) the DATA-FPGA's
 * @priv: the driver's private data structure
 *
 * LOCKING: must hold priv->lock
 */
static int fpga_do_stop(struct fpga_dev *priv)
{
        u32 val;

        /* Set the led to unprogrammed */
        ledtrig_fpga_programmed(false);

        /* Pulse the config line to reset the FPGA's */
        val = CFG_CTL_ENABLE | CFG_CTL_RESET;
        iowrite32be(val, priv->regs + FPGA_CONFIG_CONTROL);
        iowrite32be(0x0, priv->regs + FPGA_CONFIG_CONTROL);

        return 0;
}

static noinline int fpga_do_program(struct fpga_dev *priv)
{
        int ret;

        if (priv->bytes != priv->fw_size) {
                dev_err(priv->dev, "Incorrect bitfile size: got %zu bytes, "
                                   "should be %zu bytes\n",
                                   priv->bytes, priv->fw_size);
                return -EINVAL;
        }

        if (!fpga_power_enabled(priv)) {
                dev_err(priv->dev, "Power not enabled\n");
                return -EINVAL;
        }

        if (!fpga_power_good(priv)) {
                dev_err(priv->dev, "Power not good\n");
                return -EINVAL;
        }

        /* Set the LED to unprogrammed */
        ledtrig_fpga_programmed(false);

        /* Try to program the FPGA's using DMA */
        ret = fpga_program_dma(priv);

        /* If DMA failed or doesn't exist, try with CPU */
        if (ret) {
                dev_warn(priv->dev, "Falling back to CPU programming\n");
                ret = fpga_program_cpu(priv);
        }

        if (ret) {
                dev_err(priv->dev, "Unable to program FPGA's\n");
                return ret;
        }

        /* Drop the firmware bitfile from memory */
        fpga_drop_firmware_data(priv);

        dev_dbg(priv->dev, "FPGA programming successful\n");
        ledtrig_fpga_programmed(true);

        return 0;
}

/*
 * File Operations
 */

static int fpga_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_dev *priv = container_of(filp->private_data,
                                             struct fpga_dev, miscdev);
        unsigned int nr_pages;
        int ret;

        /* We only allow one process at a time */
        ret = mutex_lock_interruptible(&priv->lock);
        if (ret)
                return ret;

        filp->private_data = priv;
        kref_get(&priv->ref);

        /* Truncation: drop any existing data */
        if (filp->f_flags & O_TRUNC)
                priv->bytes = 0;

        /* Check if we have already allocated a buffer */
        if (priv->buf_allocated)
                return 0;

        /* Allocate a buffer to hold enough data for the bitfile */
        nr_pages = DIV_ROUND_UP(priv->fw_size, PAGE_SIZE);
        ret = fpga_dma_init(priv, nr_pages);
        if (ret) {
                dev_err(priv->dev, "unable to allocate data buffer\n");
                mutex_unlock(&priv->lock);
                kref_put(&priv->ref, fpga_dev_remove);
                return ret;
        }

        priv->buf_allocated = true;
        return 0;
}

static int fpga_release(struct inode *inode, struct file *filp)
{
        struct fpga_dev *priv = filp->private_data;

        mutex_unlock(&priv->lock);
        kref_put(&priv->ref, fpga_dev_remove);
        return 0;
}

static ssize_t fpga_write(struct file *filp, const char __user *buf,
                          size_t count, loff_t *f_pos)
{
        struct fpga_dev *priv = filp->private_data;

        /* FPGA bitfiles have an exact size: disallow anything else */
        if (priv->bytes >= priv->fw_size)
                return -ENOSPC;

        count = min_t(size_t, priv->fw_size - priv->bytes, count);
        if (copy_from_user(priv->vaddr + priv->bytes, buf, count))
                return -EFAULT;

        priv->bytes += count;
        return count;
}

static ssize_t fpga_read(struct file *filp, char __user *buf, size_t count,
                         loff_t *f_pos)
{
        struct fpga_dev *priv = filp->private_data;
        return simple_read_from_buffer(buf, count, f_pos,
                                       priv->vaddr, priv->bytes);
}

static loff_t fpga_llseek(struct file *filp, loff_t offset, int origin)
{
        struct fpga_dev *priv = filp->private_data;

        /* only read-only opens are allowed to seek */
        if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
                return -EINVAL;

        return fixed_size_llseek(filp, offset, origin, priv->fw_size);
}

static const struct file_operations fpga_fops = {
        .open           = fpga_open,
        .release        = fpga_release,
        .write          = fpga_write,
        .read           = fpga_read,
        .llseek         = fpga_llseek,
};

/*
 * Device Attributes
 */

static ssize_t pfail_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct fpga_dev *priv = dev_get_drvdata(dev);
        u8 val;

        val = ioread8(priv->regs + CTL_PWR_FAIL);
        return snprintf(buf, PAGE_SIZE, "0x%.2x\n", val);
}

static ssize_t pgood_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct fpga_dev *priv = dev_get_drvdata(dev);
        return snprintf(buf, PAGE_SIZE, "%d\n", fpga_power_good(priv));
}

static ssize_t penable_show(struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct fpga_dev *priv = dev_get_drvdata(dev);
        return snprintf(buf, PAGE_SIZE, "%d\n", fpga_power_enabled(priv));
}

static ssize_t penable_store(struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct fpga_dev *priv = dev_get_drvdata(dev);
        unsigned long val;
        int ret;

        ret = kstrtoul(buf, 0, &val);
        if (ret)
                return ret;

        if (val) {
                ret = fpga_enable_power_supplies(priv);
                if (ret)
                        return ret;
        } else {
                fpga_do_stop(priv);
                fpga_disable_power_supplies(priv);
        }

        return count;
}

static ssize_t program_show(struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct fpga_dev *priv = dev_get_drvdata(dev);
        return snprintf(buf, PAGE_SIZE, "%d\n", fpga_running(priv));
}

static ssize_t program_store(struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct fpga_dev *priv = dev_get_drvdata(dev);
        unsigned long val;
        int ret;

        ret = kstrtoul(buf, 0, &val);
        if (ret)
                return ret;

        /* We can't have an image writer and be programming simultaneously */
        if (mutex_lock_interruptible(&priv->lock))
                return -ERESTARTSYS;

        /* Program or Reset the FPGA's */
        ret = val ? fpga_do_program(priv) : fpga_do_stop(priv);
        if (ret)
                goto out_unlock;

        /* Success */
        ret = count;

out_unlock:
        mutex_unlock(&priv->lock);
        return ret;
}

static DEVICE_ATTR(power_fail, S_IRUGO, pfail_show, NULL);
static DEVICE_ATTR(power_good, S_IRUGO, pgood_show, NULL);
static DEVICE_ATTR(power_enable, S_IRUGO | S_IWUSR,
                   penable_show, penable_store);

static DEVICE_ATTR(program, S_IRUGO | S_IWUSR,
                   program_show, program_store);

static struct attribute *fpga_attributes[] = {
        &dev_attr_power_fail.attr,
        &dev_attr_power_good.attr,
        &dev_attr_power_enable.attr,
        &dev_attr_program.attr,
        NULL,
};

static const struct attribute_group fpga_attr_group = {
        .attrs = fpga_attributes,
};

/*
 * OpenFirmware Device Subsystem
 */

#define SYS_REG_VERSION         0x00
#define SYS_REG_GEOGRAPHIC      0x10

static bool dma_filter(struct dma_chan *chan, void *data)
{
        /*
         * DMA Channel #0 is the only acceptable device
         *
         * This probably won't survive an unload/load cycle of the Freescale
         * DMAEngine driver, but that won't be a problem
         */
        return chan->chan_id == 0 && chan->device->dev_id == 0;
}

static int fpga_of_remove(struct platform_device *op)
{
        struct fpga_dev *priv = platform_get_drvdata(op);
        struct device *this_device = priv->miscdev.this_device;

        sysfs_remove_group(&this_device->kobj, &fpga_attr_group);
        misc_deregister(&priv->miscdev);

        free_irq(priv->irq, priv);
        irq_dispose_mapping(priv->irq);

        /* make sure the power supplies are off */
        fpga_disable_power_supplies(priv);

        /* unmap registers */
        iounmap(priv->immr);
        iounmap(priv->regs);

        dma_release_channel(priv->chan);

        /* drop our reference to the private data structure */
        kref_put(&priv->ref, fpga_dev_remove);
        return 0;
}

/* CTL-CPLD Version Register */
#define CTL_CPLD_VERSION        0x2000

static int fpga_of_probe(struct platform_device *op)
{
        struct device_node *of_node = op->dev.of_node;
        struct device *this_device;
        struct fpga_dev *priv;
        dma_cap_mask_t mask;
        u32 ver;
        int ret;

        /* Allocate private data */
        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv) {
                dev_err(&op->dev, "Unable to allocate private data\n");
                ret = -ENOMEM;
                goto out_return;
        }

        /* Setup the miscdevice */
        priv->miscdev.minor = MISC_DYNAMIC_MINOR;
        priv->miscdev.name = drv_name;
        priv->miscdev.fops = &fpga_fops;

        kref_init(&priv->ref);

        platform_set_drvdata(op, priv);
        priv->dev = &op->dev;
        mutex_init(&priv->lock);
        init_completion(&priv->completion);

        dev_set_drvdata(priv->dev, priv);
        dma_cap_zero(mask);
        dma_cap_set(DMA_MEMCPY, mask);
        dma_cap_set(DMA_SLAVE, mask);
        dma_cap_set(DMA_SG, mask);

        /* Get control of DMA channel #0 */
        priv->chan = dma_request_channel(mask, dma_filter, NULL);
        if (!priv->chan) {
                dev_err(&op->dev, "Unable to acquire DMA channel #0\n");
                ret = -ENODEV;
                goto out_free_priv;
        }

        /* Remap 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_dma_release_channel;
        }

        /* Remap the IMMR for use */
        priv->immr = ioremap(get_immrbase(), 0x100000);
        if (!priv->immr) {
                dev_err(&op->dev, "Unable to ioremap IMMR\n");
                ret = -ENOMEM;
                goto out_unmap_regs;
        }

        /*
         * Check that external DMA is configured
         *
         * U-Boot does this for us, but we should check it and bail out if
         * there is a problem. Failing to have this register setup correctly
         * will cause the DMA controller to transfer a single cacheline
         * worth of data, then wedge itself.
         */
        if ((ioread32be(priv->immr + 0x114) & 0xE00) != 0xE00) {
                dev_err(&op->dev, "External DMA control not configured\n");
                ret = -ENODEV;
                goto out_unmap_immr;
        }

        /*
         * Check the CTL-CPLD version
         *
         * This driver uses the CTL-CPLD DATA-FPGA power sequencer, and we
         * don't want to run on any version of the CTL-CPLD that does not use
         * a compatible register layout.
         *
         * v2: changed register layout, added power sequencer
         * v3: added glitch filter on the i2c overcurrent/overtemp outputs
         */
        ver = ioread8(priv->regs + CTL_CPLD_VERSION);
        if (ver != 0x02 && ver != 0x03) {
                dev_err(&op->dev, "CTL-CPLD is not version 0x02 or 0x03!\n");
                ret = -ENODEV;
                goto out_unmap_immr;
        }

        /* Set the exact size that the firmware image should be */
        ver = ioread32be(priv->regs + SYS_REG_VERSION);
        priv->fw_size = (ver & (1 << 18)) ? FW_SIZE_EP2S130 : FW_SIZE_EP2S90;

        /* 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_unmap_immr;
        }

        /* Request the IRQ */
        ret = request_irq(priv->irq, fpga_irq, IRQF_SHARED, drv_name, priv);
        if (ret) {
                dev_err(&op->dev, "Unable to request IRQ %d\n", priv->irq);
                ret = -ENODEV;
                goto out_irq_dispose_mapping;
        }

        /* Reset and stop the FPGA's, just in case */
        fpga_do_stop(priv);

        /* Register the miscdevice */
        ret = misc_register(&priv->miscdev);
        if (ret) {
                dev_err(&op->dev, "Unable to register miscdevice\n");
                goto out_free_irq;
        }

        /* Create the sysfs files */
        this_device = priv->miscdev.this_device;
        dev_set_drvdata(this_device, priv);
        ret = sysfs_create_group(&this_device->kobj, &fpga_attr_group);
        if (ret) {
                dev_err(&op->dev, "Unable to create sysfs files\n");
                goto out_misc_deregister;
        }

        dev_info(priv->dev, "CARMA FPGA Programmer: %s rev%s with %s FPGAs\n",
                        (ver & (1 << 17)) ? "Correlator" : "Digitizer",
                        (ver & (1 << 16)) ? "B" : "A",
                        (ver & (1 << 18)) ? "EP2S130" : "EP2S90");

        return 0;

out_misc_deregister:
        misc_deregister(&priv->miscdev);
out_free_irq:
        free_irq(priv->irq, priv);
out_irq_dispose_mapping:
        irq_dispose_mapping(priv->irq);
out_unmap_immr:
        iounmap(priv->immr);
out_unmap_regs:
        iounmap(priv->regs);
out_dma_release_channel:
        dma_release_channel(priv->chan);
out_free_priv:
        kref_put(&priv->ref, fpga_dev_remove);
out_return:
        return ret;
}

static const struct of_device_id fpga_of_match[] = {
        { .compatible = "carma,fpga-programmer", },
        {},
};

static struct platform_driver fpga_of_driver = {
        .probe          = fpga_of_probe,
        .remove         = fpga_of_remove,
        .driver         = {
                .name           = drv_name,
                .of_match_table = fpga_of_match,
        },
};

/*
 * Module Init / Exit
 */

static int __init fpga_init(void)
{
        led_trigger_register_simple("fpga", &ledtrig_fpga);
        return platform_driver_register(&fpga_of_driver);
}

static void __exit fpga_exit(void)
{
        platform_driver_unregister(&fpga_of_driver);
        led_trigger_unregister_simple(ledtrig_fpga);
}

MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
MODULE_DESCRIPTION("CARMA Board DATA-FPGA Programmer");
MODULE_LICENSE("GPL");

module_init(fpga_init);
module_exit(fpga_exit);