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SubjectRe: [PATCH 2/2] fpga: add FPGA manager debugfs
Date
Hi,

On Thursday, August 16, 2018 10:04:51 PM CEST Alan Tull wrote:
> On Thu, Aug 16, 2018 at 1:59 PM, Moritz Fischer <mdf@kernel.org> wrote:
> > Hi Alan,
>
> Hi Moritz,
>
> > comments inline. While I see how this is useful, I have the
> > suspicion that from the moment this gets merged vendor kernels
> > will just default to use this ...
>
> Yeah, I have that suspicion as well. That's probably why I sat on
> this and didn't upstream it for 2 years. But on the other hand, I
> keep hearing of lots of cases of people implementing this
> independently anyway. At least if it is debugfs, it makes it clear
> that it's not intended for production use.

I'm one of those guys who implemented this independently.

@Mortiz
I do not see how this can be a bad thing (from what you wrote I guess you
prefer another interface). Which interface to use depends on the use case.
If you have this suspicion it's, I guess, because such interface it is
extremely easy to use.

@Alan
DebugFS can be a first step, but I would go for a normal device in /dev at
some point. I do not see why this should not be used in production

Below, again, my code that does the same thing. I already posted this in
another thread [1] but probably this is the best place. As I said in the
other thread, this is what I did quickly last year to make things working
for us (where this kind of interface is a must). Unfortunately, I do not
have time to review my own code and improve it.


[1] https://lkml.org/lkml/2018/8/16/107


-----
From d6a6df9515c5e92cc74b8948c3c10ac9cbeec6d2 Mon Sep 17 00:00:00 2001
From: Federico Vaga <federico.vaga@vaga.pv.it>
Date: Mon, 20 Nov 2017 14:40:26 +0100
Subject: [PATCH] fpga: program from user-space

Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
---
Documentation/fpga/fpga-mgr.txt | 3 +
drivers/fpga/fpga-mgr.c | 261 ++++++++++++++++++++++++++++++++++++
++
+-
include/linux/fpga/fpga-mgr.h | 19 +++
3 files changed, 281 insertions(+), 2 deletions(-)

diff --git a/Documentation/fpga/fpga-mgr.txt b/Documentation/fpga/fpga-
mgr.txt
index 78f197f..397dae9 100644
--- a/Documentation/fpga/fpga-mgr.txt
+++ b/Documentation/fpga/fpga-mgr.txt
@@ -197,3 +197,6 @@ to put the FPGA into operating mode.
The ops include a .state function which will read the hardware FPGA
manager
and
return a code of type enum fpga_mgr_states. It doesn't result in a change
in
hardware state.
+
+Configuring the FPGA from user-space
+====================================
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index 6441f91..964b7e4 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -27,10 +27,56 @@
#include <linux/slab.h>
#include <linux/scatterlist.h>
#include <linux/highmem.h>
+#include <linux/spinlock.h>
#include <linux/version.h>
+#include <linux/cdev.h>
+#include <linux/list.h>

static DEFINE_IDA(fpga_mgr_ida);
static struct class *fpga_mgr_class;
+static dev_t fpga_mgr_devt;
+
+/**
+ * struct fpga_image_chunck - FPGA configuration chunck
+ * @data: chunk data
+ * @size: chunk data size
+ * @list: for the linked list of chunks
+ */
+struct fpga_image_chunk {
+ void *data;
+ size_t size;
+ struct list_head list;
+};
+#define CHUNK_MAX_SIZE (PAGE_SIZE)
+
+/**
+ * struct fpga_user_load - structure to handle configuration from user-
space
+ * @mgr: pointer to the FPGA manager
+ * @chunk_list: HEAD point of a linked list of FPGA chunks
+ * @n_chunks: number of chunks in the list
+ * @lock: it protects: chunk_list, n_chunks
+ */
+struct fpga_user_load {
+ struct fpga_manager *mgr;
+ struct list_head chunk_list;
+ unsigned int n_chunks;
+ struct spinlock lock;
+};
+
+
+/**
+ * It sets by default a huge timeout for configuration coming from user-
space
+ * just to play safe.
+ *
+ * FIXME what about sysfs parameters to adjust it? The flag bit in
particular
+ */
+struct fpga_image_info default_user_info = {
+ .flags = 0,
+ .enable_timeout_us = 10000000, /* 10s */
+ .disable_timeout_us = 10000000, /* 10s */
+ .config_complete_timeout_us = 10000000, /* 10s */
+};
+

/*
* Call the low level driver's write_init function. This will do the
@@ -310,6 +356,158 @@ int fpga_mgr_firmware_load(struct fpga_manager *mgr,
}
EXPORT_SYMBOL_GPL(fpga_mgr_firmware_load);

+
+static int fpga_mgr_open(struct inode *inode, struct file *file)
+{
+ struct fpga_manager *mgr = container_of(inode->i_cdev,
+ struct fpga_manager,
+ cdev);
+ struct fpga_user_load *usr;
+ int ret;
+
+ /* Allow the user-space programming only if user unlocked the FPGA
*/
+ if (!test_bit(FPGA_MGR_FLAG_UNLOCK, mgr->flags)) {
+ dev_info(&mgr->dev, "The FPGA programming is locked\n");
+ return -EPERM;
+ }
+
+ ret = mutex_trylock(&mgr->usr_mutex);
+ if (ret == 0)
+ return -EBUSY;
+
+ usr = kzalloc(sizeof(struct fpga_user_load), GFP_KERNEL);
+ if (!usr) {
+ ret = -ENOMEM;
+ goto err_alloc;
+ }
+
+ usr->mgr = mgr;
+ spin_lock_init(&usr->lock);
+ INIT_LIST_HEAD(&usr->chunk_list);
+ file->private_data = usr;
+
+ return 0;
+
+err_alloc:
+ spin_lock(&mgr->lock);
+ clear_bit(FPGA_MGR_FLAG_UNLOCK, mgr->flags);
+ spin_unlock(&mgr->lock);
+ mutex_unlock(&mgr->usr_mutex);
+ return ret;
+}
+
+
+static int fpga_mgr_flush(struct file *file, fl_owner_t id)
+{
+ struct fpga_user_load *usr = file->private_data;
+ struct fpga_image_chunk *chunk, *tmp;
+ struct sg_table sgt;
+ struct scatterlist *sg;
+ int err = 0;
+
+ if (!usr->n_chunks)
+ return 0;
+
+ err = sg_alloc_table(&sgt, usr->n_chunks, GFP_KERNEL);
+ if (err)
+ goto out;
+
+ sg = sgt.sgl;
+ list_for_each_entry(chunk, &usr->chunk_list, list) {
+ sg_set_buf(sg, chunk->data, chunk->size);
+ sg = sg_next(sg);
+ if (!sg)
+ break;
+ }
+
+ err = fpga_mgr_buf_load_sg(usr->mgr,
+ &default_user_info,
+ &sgt);
+ sg_free_table(&sgt);
+
+out:
+ /* Remove all chunks */
+ spin_lock(&usr->lock);
+ list_for_each_entry_safe(chunk, tmp, &usr->chunk_list, list) {
+ list_del(&chunk->list);
+ kfree(chunk->data);
+ kfree(chunk);
+ usr->n_chunks--;
+ }
+ spin_unlock(&usr->lock);
+
+ return err;
+}
+
+
+static int fpga_mgr_close(struct inode *inode, struct file *file)
+{
+ struct fpga_user_load *usr = file->private_data;
+ struct fpga_manager *mgr = usr->mgr;
+
+ kfree(usr);
+
+ spin_lock(&mgr->lock);
+ clear_bit(FPGA_MGR_FLAG_UNLOCK, mgr->flags);
+ spin_unlock(&mgr->lock);
+
+ mutex_unlock(&mgr->usr_mutex);
+
+ return 0;
+}
+
+
+static ssize_t fpga_mgr_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *offp)
+{
+ struct fpga_user_load *usr = file->private_data;
+ struct fpga_image_chunk *chunk;
+ int err;
+
+ chunk = kmalloc(sizeof(struct fpga_image_chunk), GFP_KERNEL);
+ if (!chunk)
+ return -ENOMEM;
+
+ chunk->size = count > CHUNK_MAX_SIZE ? CHUNK_MAX_SIZE : count;
+ chunk->data = kmalloc(chunk->size, GFP_KERNEL);
+ if (!chunk->data) {
+ err = -ENOMEM;
+ goto err_buf_alloc;
+ }
+
+ err = copy_from_user(chunk->data, buf, chunk->size);
+ if(err)
+ goto err_buf_copy;
+
+ spin_lock(&usr->lock);
+ list_add_tail(&chunk->list, &usr->chunk_list);
+ usr->n_chunks++;
+ spin_unlock(&usr->lock);
+
+ *offp += count;
+
+ return chunk->size;
+
+err_buf_copy:
+ kfree(chunk->data);
+err_buf_alloc:
+ kfree(chunk);
+ return err;
+}
+
+
+/**
+ * Char device operation
+ */
+static const struct file_operations fpga_mgr_fops = {
+ .owner = THIS_MODULE,
+ .open = fpga_mgr_open,
+ .flush = fpga_mgr_flush,
+ .release = fpga_mgr_close,
+ .write = fpga_mgr_write,
+};
+
+
static const char * const state_str[] = {
[FPGA_MGR_STATE_UNKNOWN] = "unknown",
[FPGA_MGR_STATE_POWER_OFF] = "power off",
@@ -352,13 +550,43 @@ static ssize_t state_show(struct device *dev,
return sprintf(buf, "%s\n", state_str[mgr->state]);
}

+static ssize_t config_lock_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct fpga_manager *mgr = to_fpga_manager(dev);
+
+ if (test_bit(FPGA_MGR_FLAG_UNLOCK, mgr->flags))
+ return sprintf(buf, "unlock\n");
+ return sprintf(buf, "lock\n");
+}
+
+static ssize_t config_lock_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct fpga_manager *mgr = to_fpga_manager(dev);
+
+ spin_lock(&mgr->lock);
+ if (strncmp(buf, "lock" , min(4, (int)count)) == 0)
+ clear_bit(FPGA_MGR_FLAG_UNLOCK, mgr->flags);
+ else if (strncmp(buf, "unlock" , min(6, (int)count)) == 0)
+ set_bit(FPGA_MGR_FLAG_UNLOCK, mgr->flags);
+ else
+ count = -EINVAL;
+ spin_unlock(&mgr->lock);
+
+ return count;
+}
+
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,11,0)
static DEVICE_ATTR_RO(name);
static DEVICE_ATTR_RO(state);
+static DEVICE_ATTR_RW(config_lock);

static struct attribute *fpga_mgr_attrs[] = {
&dev_attr_name.attr,
&dev_attr_state.attr,
+ &dev_attr_lock.attr,
NULL,
};
ATTRIBUTE_GROUPS(fpga_mgr);
@@ -367,6 +595,9 @@ ATTRIBUTE_GROUPS(fpga_mgr);
static struct device_attribute fpga_mgr_attrs[] = {
__ATTR(name, S_IRUGO, name_show, NULL),
__ATTR(state, S_IRUGO, state_show, NULL),
+ __ATTR(config_lock, S_IRUGO | S_IWUSR | S_IRGRP | S_IWGRP,
+ config_lock_show, config_lock_store),
+ __ATTR_NULL,
};
#endif

@@ -507,6 +738,8 @@ int fpga_mgr_register(struct device *dev, const char
*name,
}

mutex_init(&mgr->ref_mutex);
+ mutex_init(&mgr->usr_mutex);
+ spin_lock_init(&mgr->lock);

mgr->name = name;
mgr->mops = mops;
@@ -524,12 +757,19 @@ int fpga_mgr_register(struct device *dev, const char
*name,
mgr->dev.parent = dev;
mgr->dev.of_node = dev->of_node;
mgr->dev.id = id;
+ mgr->dev.devt = MKDEV(MAJOR(fpga_mgr_devt), id);
dev_set_drvdata(dev, mgr);

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

+ cdev_init(&mgr->cdev, &fpga_mgr_fops);
+ mgr->cdev.owner = THIS_MODULE;
+ ret = cdev_add(&mgr->cdev, mgr->dev.devt, 1);
+ if (ret)
+ goto err_cdev;
+
ret = device_add(&mgr->dev);
if (ret)
goto error_device;
@@ -539,6 +779,8 @@ int fpga_mgr_register(struct device *dev, const char
*name,
return 0;

error_device:
+ cdev_del(&mgr->cdev);
+err_cdev:
ida_simple_remove(&fpga_mgr_ida, id);
error_kfree:
kfree(mgr);
@@ -572,17 +814,27 @@ static void fpga_mgr_dev_release(struct device *dev)
{
struct fpga_manager *mgr = to_fpga_manager(dev);

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

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

+ err = alloc_chrdev_region(&fpga_mgr_devt, 0, FPGA_MGR_MAX_DEV,
+ "fpga_mgr");
+ if (err)
+ return err;
+
fpga_mgr_class = class_create(THIS_MODULE, "fpga_manager");
- if (IS_ERR(fpga_mgr_class))
- return PTR_ERR(fpga_mgr_class);
+ if (IS_ERR(fpga_mgr_class)) {
+ err = PTR_ERR(fpga_mgr_class);
+ goto err_class;
+ }
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,11,0)
fpga_mgr_class->dev_groups = fpga_mgr_groups;
#else
@@ -591,12 +843,17 @@ static int __init fpga_mgr_class_init(void)
fpga_mgr_class->dev_release = fpga_mgr_dev_release;

return 0;
+
+err_class:
+ unregister_chrdev_region(fpga_mgr_devt, FPGA_MGR_MAX_DEV);
+ return err;
}

static void __exit fpga_mgr_class_exit(void)
{
class_destroy(fpga_mgr_class);
ida_destroy(&fpga_mgr_ida);
+ unregister_chrdev_region(fpga_mgr_devt, FPGA_MGR_MAX_DEV);
}

MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index bfa14bc..ae38e48 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -15,8 +15,10 @@
* 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/cdev.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
+#include <linux/spinlock.h>

#ifndef _LINUX_FPGA_MGR_H
#define _LINUX_FPGA_MGR_H
@@ -24,6 +26,8 @@
struct fpga_manager;
struct sg_table;

+#define FPGA_MGR_MAX_DEV (256)
+
/**
* enum fpga_mgr_states - fpga framework states
* @FPGA_MGR_STATE_UNKNOWN: can't determine state
@@ -118,22 +122,37 @@ struct fpga_manager_ops {
void (*fpga_remove)(struct fpga_manager *mgr);
};

+/*
+ * List of status FLAGS for the FPGA manager
+ */
+#define FPGA_MGR_FLAG_BITS (32)
+#define FPGA_MGR_FLAG_UNLOCK BIT(0)
+
/**
* struct fpga_manager - fpga manager structure
* @name: name of low level fpga manager
+ * @cdev: char device interface
* @dev: fpga manager device
* @ref_mutex: only allows one reference to fpga manager
* @state: state of fpga manager
* @mops: pointer to struct of fpga manager ops
* @priv: low level driver private date
+ * @flags: manager status bits
+ * @lock: it protects: flags
+ * @usr_mutex: only allows one user to program the FPGA
*/
struct fpga_manager {
const char *name;
+ struct cdev cdev;
struct device dev;
struct mutex ref_mutex;
enum fpga_mgr_states state;
const struct fpga_manager_ops *mops;
void *priv;
+
+ DECLARE_BITMAP(flags, FPGA_MGR_FLAG_BITS);
+ struct spinlock lock;
+ struct mutex usr_mutex;
};

#define to_fpga_manager(d) container_of(d, struct fpga_manager, dev)
--
2.15.0

--
Federico Vaga
[BE-CO-HT]


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