x86/unwinder: Handle stack overflows more gracefully

[linux/fpc-iii.git] / drivers / fpga / fpga-mgr.c

/*
 * FPGA Manager Core
 *
 *  Copyright (C) 2013-2015 Altera Corporation
 *
 * With code from the mailing list:
 * Copyright (C) 2013 Xilinx, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <linux/firmware.h>
#include <linux/fpga/fpga-mgr.h>
#include <linux/idr.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/scatterlist.h>
#include <linux/highmem.h>

static DEFINE_IDA(fpga_mgr_ida);
static struct class *fpga_mgr_class;

/*
 * Call the low level driver's write_init function.  This will do the
 * device-specific things to get the FPGA into the state where it is ready to
 * receive an FPGA image. The low level driver only gets to see the first
 * initial_header_size bytes in the buffer.
 */
static int fpga_mgr_write_init_buf(struct fpga_manager *mgr,
                                   struct fpga_image_info *info,
                                   const char *buf, size_t count)
{
        int ret;

        mgr->state = FPGA_MGR_STATE_WRITE_INIT;
        if (!mgr->mops->initial_header_size)
                ret = mgr->mops->write_init(mgr, info, NULL, 0);
        else
                ret = mgr->mops->write_init(
                    mgr, info, buf, min(mgr->mops->initial_header_size, count));

        if (ret) {
                dev_err(&mgr->dev, "Error preparing FPGA for writing\n");
                mgr->state = FPGA_MGR_STATE_WRITE_INIT_ERR;
                return ret;
        }

        return 0;
}

static int fpga_mgr_write_init_sg(struct fpga_manager *mgr,
                                  struct fpga_image_info *info,
                                  struct sg_table *sgt)
{
        struct sg_mapping_iter miter;
        size_t len;
        char *buf;
        int ret;

        if (!mgr->mops->initial_header_size)
                return fpga_mgr_write_init_buf(mgr, info, NULL, 0);

        /*
         * First try to use miter to map the first fragment to access the
         * header, this is the typical path.
         */
        sg_miter_start(&miter, sgt->sgl, sgt->nents, SG_MITER_FROM_SG);
        if (sg_miter_next(&miter) &&
            miter.length >= mgr->mops->initial_header_size) {
                ret = fpga_mgr_write_init_buf(mgr, info, miter.addr,
                                              miter.length);
                sg_miter_stop(&miter);
                return ret;
        }
        sg_miter_stop(&miter);

        /* Otherwise copy the fragments into temporary memory. */
        buf = kmalloc(mgr->mops->initial_header_size, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        len = sg_copy_to_buffer(sgt->sgl, sgt->nents, buf,
                                mgr->mops->initial_header_size);
        ret = fpga_mgr_write_init_buf(mgr, info, buf, len);

        kfree(buf);

        return ret;
}

/*
 * After all the FPGA image has been written, do the device specific steps to
 * finish and set the FPGA into operating mode.
 */
static int fpga_mgr_write_complete(struct fpga_manager *mgr,
                                   struct fpga_image_info *info)
{
        int ret;

        mgr->state = FPGA_MGR_STATE_WRITE_COMPLETE;
        ret = mgr->mops->write_complete(mgr, info);
        if (ret) {
                dev_err(&mgr->dev, "Error after writing image data to FPGA\n");
                mgr->state = FPGA_MGR_STATE_WRITE_COMPLETE_ERR;
                return ret;
        }
        mgr->state = FPGA_MGR_STATE_OPERATING;

        return 0;
}

/**
 * fpga_mgr_buf_load_sg - load fpga from image in buffer from a scatter list
 * @mgr:        fpga manager
 * @info:       fpga image specific information
 * @sgt:        scatterlist table
 *
 * Step the low level fpga manager through the device-specific steps of getting
 * an FPGA ready to be configured, writing the image to it, then doing whatever
 * post-configuration steps necessary.  This code assumes the caller got the
 * mgr pointer from of_fpga_mgr_get() or fpga_mgr_get() and checked that it is
 * not an error code.
 *
 * This is the preferred entry point for FPGA programming, it does not require
 * any contiguous kernel memory.
 *
 * Return: 0 on success, negative error code otherwise.
 */
int fpga_mgr_buf_load_sg(struct fpga_manager *mgr, struct fpga_image_info *info,
                         struct sg_table *sgt)
{
        int ret;

        ret = fpga_mgr_write_init_sg(mgr, info, sgt);
        if (ret)
                return ret;

        /* Write the FPGA image to the FPGA. */
        mgr->state = FPGA_MGR_STATE_WRITE;
        if (mgr->mops->write_sg) {
                ret = mgr->mops->write_sg(mgr, sgt);
        } else {
                struct sg_mapping_iter miter;

                sg_miter_start(&miter, sgt->sgl, sgt->nents, SG_MITER_FROM_SG);
                while (sg_miter_next(&miter)) {
                        ret = mgr->mops->write(mgr, miter.addr, miter.length);
                        if (ret)
                                break;
                }
                sg_miter_stop(&miter);
        }

        if (ret) {
                dev_err(&mgr->dev, "Error while writing image data to FPGA\n");
                mgr->state = FPGA_MGR_STATE_WRITE_ERR;
                return ret;
        }

        return fpga_mgr_write_complete(mgr, info);
}
EXPORT_SYMBOL_GPL(fpga_mgr_buf_load_sg);

static int fpga_mgr_buf_load_mapped(struct fpga_manager *mgr,
                                    struct fpga_image_info *info,
                                    const char *buf, size_t count)
{
        int ret;

        ret = fpga_mgr_write_init_buf(mgr, info, buf, count);
        if (ret)
                return ret;

        /*
         * Write the FPGA image to the FPGA.
         */
        mgr->state = FPGA_MGR_STATE_WRITE;
        ret = mgr->mops->write(mgr, buf, count);
        if (ret) {
                dev_err(&mgr->dev, "Error while writing image data to FPGA\n");
                mgr->state = FPGA_MGR_STATE_WRITE_ERR;
                return ret;
        }

        return fpga_mgr_write_complete(mgr, info);
}

/**
 * fpga_mgr_buf_load - load fpga from image in buffer
 * @mgr:        fpga manager
 * @flags:      flags setting fpga confuration modes
 * @buf:        buffer contain fpga image
 * @count:      byte count of buf
 *
 * Step the low level fpga manager through the device-specific steps of getting
 * an FPGA ready to be configured, writing the image to it, then doing whatever
 * post-configuration steps necessary.  This code assumes the caller got the
 * mgr pointer from of_fpga_mgr_get() and checked that it is not an error code.
 *
 * Return: 0 on success, negative error code otherwise.
 */
int fpga_mgr_buf_load(struct fpga_manager *mgr, struct fpga_image_info *info,
                      const char *buf, size_t count)
{
        struct page **pages;
        struct sg_table sgt;
        const void *p;
        int nr_pages;
        int index;
        int rc;

        /*
         * This is just a fast path if the caller has already created a
         * contiguous kernel buffer and the driver doesn't require SG, non-SG
         * drivers will still work on the slow path.
         */
        if (mgr->mops->write)
                return fpga_mgr_buf_load_mapped(mgr, info, buf, count);

        /*
         * Convert the linear kernel pointer into a sg_table of pages for use
         * by the driver.
         */
        nr_pages = DIV_ROUND_UP((unsigned long)buf + count, PAGE_SIZE) -
                   (unsigned long)buf / PAGE_SIZE;
        pages = kmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
        if (!pages)
                return -ENOMEM;

        p = buf - offset_in_page(buf);
        for (index = 0; index < nr_pages; index++) {
                if (is_vmalloc_addr(p))
                        pages[index] = vmalloc_to_page(p);
                else
                        pages[index] = kmap_to_page((void *)p);
                if (!pages[index]) {
                        kfree(pages);
                        return -EFAULT;
                }
                p += PAGE_SIZE;
        }

        /*
         * The temporary pages list is used to code share the merging algorithm
         * in sg_alloc_table_from_pages
         */
        rc = sg_alloc_table_from_pages(&sgt, pages, index, offset_in_page(buf),
                                       count, GFP_KERNEL);
        kfree(pages);
        if (rc)
                return rc;

        rc = fpga_mgr_buf_load_sg(mgr, info, &sgt);
        sg_free_table(&sgt);

        return rc;
}
EXPORT_SYMBOL_GPL(fpga_mgr_buf_load);

/**
 * fpga_mgr_firmware_load - request firmware and load to fpga
 * @mgr:        fpga manager
 * @info:       fpga image specific information
 * @image_name: name of image file on the firmware search path
 *
 * Request an FPGA image using the firmware class, then write out to the FPGA.
 * Update the state before each step to provide info on what step failed if
 * there is a failure.  This code assumes the caller got the mgr pointer
 * from of_fpga_mgr_get() or fpga_mgr_get() and checked that it is not an error
 * code.
 *
 * Return: 0 on success, negative error code otherwise.
 */
int fpga_mgr_firmware_load(struct fpga_manager *mgr,
                           struct fpga_image_info *info,
                           const char *image_name)
{
        struct device *dev = &mgr->dev;
        const struct firmware *fw;
        int ret;

        dev_info(dev, "writing %s to %s\n", image_name, mgr->name);

        mgr->state = FPGA_MGR_STATE_FIRMWARE_REQ;

        ret = request_firmware(&fw, image_name, dev);
        if (ret) {
                mgr->state = FPGA_MGR_STATE_FIRMWARE_REQ_ERR;
                dev_err(dev, "Error requesting firmware %s\n", image_name);
                return ret;
        }

        ret = fpga_mgr_buf_load(mgr, info, fw->data, fw->size);

        release_firmware(fw);

        return ret;
}
EXPORT_SYMBOL_GPL(fpga_mgr_firmware_load);

static const char * const state_str[] = {
        [FPGA_MGR_STATE_UNKNOWN] =              "unknown",
        [FPGA_MGR_STATE_POWER_OFF] =            "power off",
        [FPGA_MGR_STATE_POWER_UP] =             "power up",
        [FPGA_MGR_STATE_RESET] =                "reset",

        /* requesting FPGA image from firmware */
        [FPGA_MGR_STATE_FIRMWARE_REQ] =         "firmware request",
        [FPGA_MGR_STATE_FIRMWARE_REQ_ERR] =     "firmware request error",

        /* Preparing FPGA to receive image */
        [FPGA_MGR_STATE_WRITE_INIT] =           "write init",
        [FPGA_MGR_STATE_WRITE_INIT_ERR] =       "write init error",

        /* Writing image to FPGA */
        [FPGA_MGR_STATE_WRITE] =                "write",
        [FPGA_MGR_STATE_WRITE_ERR] =            "write error",

        /* Finishing configuration after image has been written */
        [FPGA_MGR_STATE_WRITE_COMPLETE] =       "write complete",
        [FPGA_MGR_STATE_WRITE_COMPLETE_ERR] =   "write complete error",

        /* FPGA reports to be in normal operating mode */
        [FPGA_MGR_STATE_OPERATING] =            "operating",
};

static ssize_t name_show(struct device *dev,
                         struct device_attribute *attr, char *buf)
{
        struct fpga_manager *mgr = to_fpga_manager(dev);

        return sprintf(buf, "%s\n", mgr->name);
}

static ssize_t state_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct fpga_manager *mgr = to_fpga_manager(dev);

        return sprintf(buf, "%s\n", state_str[mgr->state]);
}

static DEVICE_ATTR_RO(name);
static DEVICE_ATTR_RO(state);

static struct attribute *fpga_mgr_attrs[] = {
        &dev_attr_name.attr,
        &dev_attr_state.attr,
        NULL,
};
ATTRIBUTE_GROUPS(fpga_mgr);

static struct fpga_manager *__fpga_mgr_get(struct device *dev)
{
        struct fpga_manager *mgr;
        int ret = -ENODEV;

        mgr = to_fpga_manager(dev);
        if (!mgr)
                goto err_dev;

        /* Get exclusive use of fpga manager */
        if (!mutex_trylock(&mgr->ref_mutex)) {
                ret = -EBUSY;
                goto err_dev;
        }

        if (!try_module_get(dev->parent->driver->owner))
                goto err_ll_mod;

        return mgr;

err_ll_mod:
        mutex_unlock(&mgr->ref_mutex);
err_dev:
        put_device(dev);
        return ERR_PTR(ret);
}

static int fpga_mgr_dev_match(struct device *dev, const void *data)
{
        return dev->parent == data;
}

/**
 * fpga_mgr_get - get an exclusive reference to a fpga mgr
 * @dev:        parent device that fpga mgr was registered with
 *
 * Given a device, get an exclusive reference to a fpga mgr.
 *
 * Return: fpga manager struct or IS_ERR() condition containing error code.
 */
struct fpga_manager *fpga_mgr_get(struct device *dev)
{
        struct device *mgr_dev = class_find_device(fpga_mgr_class, NULL, dev,
                                                   fpga_mgr_dev_match);
        if (!mgr_dev)
                return ERR_PTR(-ENODEV);

        return __fpga_mgr_get(mgr_dev);
}
EXPORT_SYMBOL_GPL(fpga_mgr_get);

static int fpga_mgr_of_node_match(struct device *dev, const void *data)
{
        return dev->of_node == data;
}

/**
 * of_fpga_mgr_get - get an exclusive reference to a fpga mgr
 * @node:       device node
 *
 * Given a device node, get an exclusive reference to a fpga mgr.
 *
 * Return: fpga manager struct or IS_ERR() condition containing error code.
 */
struct fpga_manager *of_fpga_mgr_get(struct device_node *node)
{
        struct device *dev;

        dev = class_find_device(fpga_mgr_class, NULL, node,
                                fpga_mgr_of_node_match);
        if (!dev)
                return ERR_PTR(-ENODEV);

        return __fpga_mgr_get(dev);
}
EXPORT_SYMBOL_GPL(of_fpga_mgr_get);

/**
 * fpga_mgr_put - release a reference to a fpga manager
 * @mgr:        fpga manager structure
 */
void fpga_mgr_put(struct fpga_manager *mgr)
{
        module_put(mgr->dev.parent->driver->owner);
        mutex_unlock(&mgr->ref_mutex);
        put_device(&mgr->dev);
}
EXPORT_SYMBOL_GPL(fpga_mgr_put);

/**
 * fpga_mgr_register - register a low level fpga manager driver
 * @dev:        fpga manager device from pdev
 * @name:       fpga manager name
 * @mops:       pointer to structure of fpga manager ops
 * @priv:       fpga manager private data
 *
 * Return: 0 on success, negative error code otherwise.
 */
int fpga_mgr_register(struct device *dev, const char *name,
                      const struct fpga_manager_ops *mops,
                      void *priv)
{
        struct fpga_manager *mgr;
        int id, ret;

        if (!mops || !mops->write_complete || !mops->state ||
            !mops->write_init || (!mops->write && !mops->write_sg) ||
            (mops->write && mops->write_sg)) {
                dev_err(dev, "Attempt to register without fpga_manager_ops\n");
                return -EINVAL;
        }

        if (!name || !strlen(name)) {
                dev_err(dev, "Attempt to register with no name!\n");
                return -EINVAL;
        }

        mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
        if (!mgr)
                return -ENOMEM;

        id = ida_simple_get(&fpga_mgr_ida, 0, 0, GFP_KERNEL);
        if (id < 0) {
                ret = id;
                goto error_kfree;
        }

        mutex_init(&mgr->ref_mutex);

        mgr->name = name;
        mgr->mops = mops;
        mgr->priv = priv;

        /*
         * Initialize framework state by requesting low level driver read state
         * from device.  FPGA may be in reset mode or may have been programmed
         * by bootloader or EEPROM.
         */
        mgr->state = mgr->mops->state(mgr);

        device_initialize(&mgr->dev);
        mgr->dev.class = fpga_mgr_class;
        mgr->dev.parent = dev;
        mgr->dev.of_node = dev->of_node;
        mgr->dev.id = id;
        dev_set_drvdata(dev, mgr);

        ret = dev_set_name(&mgr->dev, "fpga%d", id);
        if (ret)
                goto error_device;

        ret = device_add(&mgr->dev);
        if (ret)
                goto error_device;

        dev_info(&mgr->dev, "%s registered\n", mgr->name);

        return 0;

error_device:
        ida_simple_remove(&fpga_mgr_ida, id);
error_kfree:
        kfree(mgr);

        return ret;
}
EXPORT_SYMBOL_GPL(fpga_mgr_register);

/**
 * fpga_mgr_unregister - unregister a low level fpga manager driver
 * @dev:        fpga manager device from pdev
 */
void fpga_mgr_unregister(struct device *dev)
{
        struct fpga_manager *mgr = dev_get_drvdata(dev);

        dev_info(&mgr->dev, "%s %s\n", __func__, mgr->name);

        /*
         * If the low level driver provides a method for putting fpga into
         * a desired state upon unregister, do it.
         */
        if (mgr->mops->fpga_remove)
                mgr->mops->fpga_remove(mgr);

        device_unregister(&mgr->dev);
}
EXPORT_SYMBOL_GPL(fpga_mgr_unregister);

static void fpga_mgr_dev_release(struct device *dev)
{
        struct fpga_manager *mgr = to_fpga_manager(dev);

        ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
        kfree(mgr);
}

static int __init fpga_mgr_class_init(void)
{
        pr_info("FPGA manager framework\n");

        fpga_mgr_class = class_create(THIS_MODULE, "fpga_manager");
        if (IS_ERR(fpga_mgr_class))
                return PTR_ERR(fpga_mgr_class);

        fpga_mgr_class->dev_groups = fpga_mgr_groups;
        fpga_mgr_class->dev_release = fpga_mgr_dev_release;

        return 0;
}

static void __exit fpga_mgr_class_exit(void)
{
        class_destroy(fpga_mgr_class);
        ida_destroy(&fpga_mgr_ida);
}

MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
MODULE_DESCRIPTION("FPGA manager framework");
MODULE_LICENSE("GPL v2");

subsys_initcall(fpga_mgr_class_init);
module_exit(fpga_mgr_class_exit);