From aa27bf82694de73f850581d5c928d99b16032be7 Mon Sep 17 00:00:00 2001
From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Date: Mon, 17 Aug 2015 00:55:03 +0100
Subject: [PATCH] greybus: loopback: convert sample report interface to debugfs
Greg previously suggested switching over to debugfs instead of a char
interface to report raw samples to user-space. At the time we agreed not
to go for that change. However later patches in this series are made
simpler if debugfs is used instead of /dev, so it makes sense to make the
conversion now for that reason. This patch removes the char interface and
replaces it with a debugfs interface. Raw samples will be acquired from
/sys/kernel/debug/gb_loopback/raw_latency_endo0:x:y:z:w where
x = <module-id>
y = <interface-id>
z = <bundle-id>
w = <cport-number>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
---
drivers/staging/greybus/loopback.c | 177 +++++++++++------------------
1 file changed, 66 insertions(+), 111 deletions(-)
diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index 74bc2b4eec633..5f66048927a7b 100644
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -17,6 +17,7 @@
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/kfifo.h>
+#include <linux/debugfs.h>
#include <asm/div64.h>
@@ -31,16 +32,21 @@ struct gb_loopback_stats {
u32 count;
};
+struct gb_loopback_device {
+ struct dentry *root;
+ u32 count;
+};
+
+static struct gb_loopback_device gb_dev;
+
struct gb_loopback {
struct gb_connection *connection;
+ struct dentry *file;
struct kfifo kfifo;
struct mutex mutex;
struct task_struct *task;
wait_queue_head_t wq;
- dev_t dev;
- struct cdev cdev;
- struct device *device;
int type;
u32 size;
@@ -60,16 +66,9 @@ struct gb_loopback {
#define GB_LOOPBACK_FIFO_DEFAULT 8192
-static struct class *loopback_class;
-static int loopback_major;
-static const struct file_operations loopback_fops;
-static DEFINE_IDA(minors);
static unsigned kfifo_depth = GB_LOOPBACK_FIFO_DEFAULT;
module_param(kfifo_depth, uint, 0444);
-/* Number of minor devices this driver supports */
-#define NUM_MINORS 256
-
/* Maximum size of any one send data buffer we support */
#define MAX_PACKET_SIZE (PAGE_SIZE * 2)
@@ -515,35 +514,72 @@ static int gb_loopback_fn(void *data)
return 0;
}
+static int gb_loopback_dbgfs_latency_show(struct seq_file *s, void *unused)
+{
+ struct gb_loopback *gb = s->private;
+ u32 latency;
+ int retval;
+
+ if (kfifo_len(&gb->kfifo) == 0) {
+ retval = -EAGAIN;
+ goto done;
+ }
+
+ mutex_lock(&gb->mutex);
+ retval = kfifo_out(&gb->kfifo, &latency, sizeof(latency));
+ if (retval > 0) {
+ seq_printf(s, "%u", latency);
+ retval = 0;
+ }
+ mutex_unlock(&gb->mutex);
+done:
+ return retval;
+}
+
+static int gb_loopback_latency_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, gb_loopback_dbgfs_latency_show,
+ inode->i_private);
+}
+
+static const struct file_operations gb_loopback_debugfs_latency_ops = {
+ .open = gb_loopback_latency_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+#define DEBUGFS_NAMELEN 24
+
static int gb_loopback_connection_init(struct gb_connection *connection)
{
struct gb_loopback *gb;
int retval;
- int minor;
+ char name[DEBUGFS_NAMELEN];
gb = kzalloc(sizeof(*gb), GFP_KERNEL);
if (!gb)
return -ENOMEM;
gb_loopback_reset_stats(gb);
+ snprintf(name, sizeof(name), "raw_latency_endo0:%d:%d:%d:%d",
+ connection->bundle->intf->module->module_id,
+ connection->bundle->intf->interface_id,
+ connection->bundle->id,
+ connection->intf_cport_id);
+ gb->file = debugfs_create_file(name, S_IFREG | S_IRUGO, gb_dev.root, gb,
+ &gb_loopback_debugfs_latency_ops);
gb->connection = connection;
connection->private = gb;
retval = sysfs_create_groups(&connection->dev.kobj, loopback_groups);
if (retval)
- goto out_free;
-
- /* Get a minor number */
- minor = ida_simple_get(&minors, 0, 0, GFP_KERNEL);
- if (minor < 0) {
- retval = minor;
- goto out_sysfs;
- }
+ goto out_debugfs;
/* Calculate maximum payload */
gb->size_max = gb_operation_get_payload_size_max(connection);
if (gb->size_max <= sizeof(struct gb_loopback_transfer_request)) {
retval = -EINVAL;
- goto out_minor;
+ goto out_sysfs;
}
gb->size_max -= sizeof(struct gb_loopback_transfer_request);
@@ -551,21 +587,7 @@ static int gb_loopback_connection_init(struct gb_connection *connection)
if (kfifo_alloc(&gb->kfifo, kfifo_depth * sizeof(u32),
GFP_KERNEL)) {
retval = -ENOMEM;
- goto out_minor;
- }
-
- /* Create device entry */
- gb->dev = MKDEV(loopback_major, minor);
- cdev_init(&gb->cdev, &loopback_fops);
- retval = cdev_add(&gb->cdev, gb->dev, 1);
- if (retval)
- goto out_kfifo;
-
- gb->device = device_create(loopback_class, &connection->dev, gb->dev,
- gb, "gb!loopback%d", minor);
- if (IS_ERR(gb->device)) {
- retval = PTR_ERR(gb->device);
- goto out_cdev;
+ goto out_sysfs;
}
/* Fork worker thread */
@@ -574,22 +596,18 @@ static int gb_loopback_connection_init(struct gb_connection *connection)
gb->task = kthread_run(gb_loopback_fn, gb, "gb_loopback");
if (IS_ERR(gb->task)) {
retval = PTR_ERR(gb->task);
- goto out_device;
+ goto out_kfifo;
}
+ gb_dev.count++;
return 0;
-out_device:
- device_del(gb->device);
-out_cdev:
- cdev_del(&gb->cdev);
out_kfifo:
kfifo_free(&gb->kfifo);
-out_minor:
- ida_simple_remove(&minors, minor);
out_sysfs:
sysfs_remove_groups(&connection->dev.kobj, loopback_groups);
-out_free:
+out_debugfs:
+ debugfs_remove(gb->file);
connection->private = NULL;
kfree(gb);
@@ -600,15 +618,14 @@ static void gb_loopback_connection_exit(struct gb_connection *connection)
{
struct gb_loopback *gb = connection->private;
+ gb_dev.count--;
connection->private = NULL;
if (!IS_ERR_OR_NULL(gb->task))
kthread_stop(gb->task);
- device_del(gb->device);
- cdev_del(&gb->cdev);
kfifo_free(&gb->kfifo);
- ida_simple_remove(&minors, MINOR(gb->dev));
sysfs_remove_groups(&connection->dev.kobj, loopback_groups);
+ debugfs_remove(gb->file);
kfree(gb);
}
@@ -622,79 +639,17 @@ static struct gb_protocol loopback_protocol = {
.request_recv = gb_loopback_request_recv,
};
-static int loopback_open(struct inode *inode, struct file *file)
-{
- struct cdev *cdev = inode->i_cdev;
- struct gb_loopback *gb = container_of(cdev, struct gb_loopback, cdev);
-
- file->private_data = gb;
- return 0;
-}
-
-static ssize_t loopback_read(struct file *file, char __user *buf, size_t count,
- loff_t *ppos)
-{
- struct gb_loopback *gb = file->private_data;
- size_t fifo_len;
- int retval;
-
- if (!count || count % sizeof(u32))
- return -EINVAL;
-
- mutex_lock(&gb->mutex);
- fifo_len = kfifo_len(&gb->kfifo);
- if (kfifo_to_user(&gb->kfifo, buf, min(fifo_len, count), &retval) != 0)
- retval = -EIO;
- mutex_unlock(&gb->mutex);
-
- return retval;
-}
-
-static const struct file_operations loopback_fops = {
- .owner = THIS_MODULE,
- .read = loopback_read,
- .open = loopback_open,
- .llseek = noop_llseek,
-};
-
static int loopback_init(void)
{
- dev_t dev;
- int retval;
-
- loopback_class = class_create(THIS_MODULE, "gb_loopback");
- if (IS_ERR(loopback_class)) {
- retval = PTR_ERR(loopback_class);
- goto error_class;
- }
-
- retval = alloc_chrdev_region(&dev, 0, NUM_MINORS, "gb_loopback");
- if (retval < 0)
- goto error_chrdev;
-
- loopback_major = MAJOR(dev);
-
- retval = gb_protocol_register(&loopback_protocol);
- if (retval)
- goto error_gb;
-
- return 0;
-
-error_gb:
- unregister_chrdev_region(dev, NUM_MINORS);
-error_chrdev:
- class_destroy(loopback_class);
-error_class:
- return retval;
+ gb_dev.root = debugfs_create_dir("gb_loopback", NULL);
+ return gb_protocol_register(&loopback_protocol);
}
module_init(loopback_init);
static void __exit loopback_exit(void)
{
+ debugfs_remove_recursive(gb_dev.root);
gb_protocol_deregister(&loopback_protocol);
- unregister_chrdev_region(MKDEV(loopback_major, 0), NUM_MINORS);
- class_destroy(loopback_class);
- ida_destroy(&minors);
}
module_exit(loopback_exit);
--
2.30.2