char: xillybus: Move class-related functions to new xillybus_class.c

This patch is a preparation for adding another related driver, XillyUSB.
In order to share some code between the existing Xillybus driver and the
one to be added, some functions are moved to xillybus_class.c

XILLYBUS_CLASS is added to Kconfig and is common to all drivers in this
group. The relation with the existing XILLYBUS symbol is "select" rather
than "depends on" XILLYBUS_CLASS, or else "make olddefconfig" will silently
turn off XILLYBUS, which is currently enabled in several distributions.

XILLYBUS_CLASS doesn't depend on anything else, hence using it with
"select" poses no risk for a broken configuration.

After the future addition of the XillyUSB module, the tree of symbols
will be as follows:

XILLYBUS_CLASS --+-- XILLYBUS --+-- XILLYBUS_PCIE
                 |              |
                 |              +-- XILLYBUS_OF
                 |
                 +-- XILLYUSB

XILLYBUS is for drivers based upon memory registers + DMA-based interfaces,
and it's combined with XILLYBUS_PCIE and/or XILLYBUS_OF.

XILLYUSB is for the USB variant only.

Or a more detailed, bottom-up outline:

* CONFIG_XILLYBUS_PCIE -> xillybus_pcie.c: Functions related to PCIe.
* CONFIG_XILLYBUS_OF -> xillybus_of.c: Functions related to Xillybus as a
  peripheral on an FPGA / Processor combo chip.
* CONFIG_XILLYBUS -> xillybus_core.c: Functions that are common to the two
  above, mainly access to the peripheral with memory-mapped registers and
  DMA.
* CONFIG_XILLYUSB -> xillyusb.c: The driver for the USB variant, accesses
  the peripheral through the USB framework.
* CONFIG_XILLYBUS_CLASS -> xillybus_class.c: The new module, which contains
  the class and API parts that would otherwise appear both in
  xillybus_core.c and xillyusb.c. Contains utility functions for the two
  latter.

And since I'm at it, comments on the module names are added in the
Kconfig's help part.

The functions are exported with the non-GPL EXPORT_SYMBOL (a matter of
taste).

Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Link: https://lore.kernel.org/r/20210526100311.56327-2-eli.billauer@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 22 insertions, 159 deletions

diff --git a/drivers/char/xillybus/xillybus_core.c b/drivers/char/xillybus/xillybus_core.c
index 57fa68834981..0efc4fddaa94 100644
--- a/drivers/char/xillybus/xillybus_core.c
+++ b/drivers/char/xillybus/xillybus_core.c
@@ -21,7 +21,6 @@
 #include <linux/interrupt.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
-#include <linux/cdev.h>
 #include <linux/spinlock.h>
 #include <linux/mutex.h>
 #include <linux/crc32.h>
@@ -30,10 +29,11 @@
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include "xillybus.h"
+#include "xillybus_class.h"
 
 MODULE_DESCRIPTION("Xillybus core functions");
 MODULE_AUTHOR("Eli Billauer, Xillybus Ltd.");
-MODULE_VERSION("1.07");
+MODULE_VERSION("1.10");
 MODULE_ALIAS("xillybus_core");
 MODULE_LICENSE("GPL v2");
 
@@ -58,16 +58,6 @@ MODULE_LICENSE("GPL v2");
 
 static const char xillyname[] = "xillybus";
 
-static struct class *xillybus_class;
-
-/*
- * ep_list_lock is the last lock to be taken; No other lock requests are
- * allowed while holding it. It merely protects list_of_endpoints, and not
- * the endpoints listed in it.
- */
-
-static LIST_HEAD(list_of_endpoints);
-static struct mutex ep_list_lock;
 static struct workqueue_struct *xillybus_wq;
 
 /*
@@ -570,10 +560,8 @@ static int xilly_scan_idt(struct xilly_endpoint *endpoint,
 	unsigned char *scan;
 	int len;
 
-	scan = idt;
-	idt_handle->idt = idt;
-
-	scan++; /* Skip version number */
+	scan = idt + 1;
+	idt_handle->names = scan;
 
 	while ((scan <= end_of_idt) && *scan) {
 		while ((scan <= end_of_idt) && *scan++)
@@ -581,6 +569,8 @@ static int xilly_scan_idt(struct xilly_endpoint *endpoint,
 		count++;
 	}
 
+	idt_handle->names_len = scan - idt_handle->names;
+
 	scan++;
 
 	if (scan > end_of_idt) {
@@ -1407,36 +1397,20 @@ static ssize_t xillybus_write(struct file *filp, const char __user *userbuf,
 
 static int xillybus_open(struct inode *inode, struct file *filp)
 {
-	int rc = 0;
+	int rc;
 	unsigned long flags;
-	int minor = iminor(inode);
-	int major = imajor(inode);
-	struct xilly_endpoint *ep_iter, *endpoint = NULL;
+	struct xilly_endpoint *endpoint;
 	struct xilly_channel *channel;
+	int index;
 
-	mutex_lock(&ep_list_lock);
-
-	list_for_each_entry(ep_iter, &list_of_endpoints, ep_list) {
-		if ((ep_iter->major == major) &&
-		    (minor >= ep_iter->lowest_minor) &&
-		    (minor < (ep_iter->lowest_minor +
-			      ep_iter->num_channels))) {
-			endpoint = ep_iter;
-			break;
-		}
-	}
-	mutex_unlock(&ep_list_lock);
-
-	if (!endpoint) {
-		pr_err("xillybus: open() failed to find a device for major=%d and minor=%d\n",
-		       major, minor);
-		return -ENODEV;
-	}
+	rc = xillybus_find_inode(inode, (void **)&endpoint, &index);
+	if (rc)
+		return rc;
 
 	if (endpoint->fatal_error)
 		return -EIO;
 
-	channel = endpoint->channels[1 + minor - endpoint->lowest_minor];
+	channel = endpoint->channels[1 + index];
 	filp->private_data = channel;
 
 	/*
@@ -1799,95 +1773,6 @@ static const struct file_operations xillybus_fops = {
 	.poll       = xillybus_poll,
 };
 
-static int xillybus_init_chrdev(struct xilly_endpoint *endpoint,
-				const unsigned char *idt)
-{
-	int rc;
-	dev_t dev;
-	int devnum, i, minor, major;
-	char devname[48];
-	struct device *device;
-
-	rc = alloc_chrdev_region(&dev, 0, /* minor start */
-				 endpoint->num_channels,
-				 xillyname);
-	if (rc) {
-		dev_warn(endpoint->dev, "Failed to obtain major/minors");
-		return rc;
-	}
-
-	endpoint->major = major = MAJOR(dev);
-	endpoint->lowest_minor = minor = MINOR(dev);
-
-	cdev_init(&endpoint->cdev, &xillybus_fops);
-	endpoint->cdev.owner = endpoint->ephw->owner;
-	rc = cdev_add(&endpoint->cdev, MKDEV(major, minor),
-		      endpoint->num_channels);
-	if (rc) {
-		dev_warn(endpoint->dev, "Failed to add cdev. Aborting.\n");
-		goto unregister_chrdev;
-	}
-
-	idt++;
-
-	for (i = minor, devnum = 0;
-	     devnum < endpoint->num_channels;
-	     devnum++, i++) {
-		snprintf(devname, sizeof(devname)-1, "xillybus_%s", idt);
-
-		devname[sizeof(devname)-1] = 0; /* Should never matter */
-
-		while (*idt++)
-			/* Skip to next */;
-
-		device = device_create(xillybus_class,
-				       NULL,
-				       MKDEV(major, i),
-				       NULL,
-				       "%s", devname);
-
-		if (IS_ERR(device)) {
-			dev_warn(endpoint->dev,
-				 "Failed to create %s device. Aborting.\n",
-				 devname);
-			rc = -ENODEV;
-			goto unroll_device_create;
-		}
-	}
-
-	dev_info(endpoint->dev, "Created %d device files.\n",
-		 endpoint->num_channels);
-	return 0; /* succeed */
-
-unroll_device_create:
-	devnum--; i--;
-	for (; devnum >= 0; devnum--, i--)
-		device_destroy(xillybus_class, MKDEV(major, i));
-
-	cdev_del(&endpoint->cdev);
-unregister_chrdev:
-	unregister_chrdev_region(MKDEV(major, minor), endpoint->num_channels);
-
-	return rc;
-}
-
-static void xillybus_cleanup_chrdev(struct xilly_endpoint *endpoint)
-{
-	int minor;
-
-	for (minor = endpoint->lowest_minor;
-	     minor < (endpoint->lowest_minor + endpoint->num_channels);
-	     minor++)
-		device_destroy(xillybus_class, MKDEV(endpoint->major, minor));
-	cdev_del(&endpoint->cdev);
-	unregister_chrdev_region(MKDEV(endpoint->major,
-				       endpoint->lowest_minor),
-				 endpoint->num_channels);
-
-	dev_info(endpoint->dev, "Removed %d device files.\n",
-		 endpoint->num_channels);
-}
-
 struct xilly_endpoint *xillybus_init_endpoint(struct pci_dev *pdev,
 					      struct device *dev,
 					      struct xilly_endpoint_hardware
@@ -2027,28 +1912,20 @@ int xillybus_endpoint_discovery(struct xilly_endpoint *endpoint)
 	if (rc)
 		goto failed_idt;
 
-	/*
-	 * endpoint is now completely configured. We put it on the list
-	 * available to open() before registering the char device(s)
-	 */
-
-	mutex_lock(&ep_list_lock);
-	list_add_tail(&endpoint->ep_list, &list_of_endpoints);
-	mutex_unlock(&ep_list_lock);
+	rc = xillybus_init_chrdev(dev, &xillybus_fops,
+				  endpoint->ephw->owner, endpoint,
+				  idt_handle.names,
+				  idt_handle.names_len,
+				  endpoint->num_channels,
+				  xillyname, false);
 
-	rc = xillybus_init_chrdev(endpoint, idt_handle.idt);
 	if (rc)
-		goto failed_chrdevs;
+		goto failed_idt;
 
 	devres_release_group(dev, bootstrap_resources);
 
 	return 0;
 
-failed_chrdevs:
-	mutex_lock(&ep_list_lock);
-	list_del(&endpoint->ep_list);
-	mutex_unlock(&ep_list_lock);
-
 failed_idt:
 	xilly_quiesce(endpoint);
 	flush_workqueue(xillybus_wq);
@@ -2059,11 +1936,7 @@ EXPORT_SYMBOL(xillybus_endpoint_discovery);
 
 void xillybus_endpoint_remove(struct xilly_endpoint *endpoint)
 {
-	xillybus_cleanup_chrdev(endpoint);
-
-	mutex_lock(&ep_list_lock);
-	list_del(&endpoint->ep_list);
-	mutex_unlock(&ep_list_lock);
+	xillybus_cleanup_chrdev(endpoint, endpoint->dev);
 
 	xilly_quiesce(endpoint);
 
@@ -2077,17 +1950,9 @@ EXPORT_SYMBOL(xillybus_endpoint_remove);
 
 static int __init xillybus_init(void)
 {
-	mutex_init(&ep_list_lock);
-
-	xillybus_class = class_create(THIS_MODULE, xillyname);
-	if (IS_ERR(xillybus_class))
-		return PTR_ERR(xillybus_class);
-
 	xillybus_wq = alloc_workqueue(xillyname, 0, 0);
-	if (!xillybus_wq) {
-		class_destroy(xillybus_class);
+	if (!xillybus_wq)
 		return -ENOMEM;
-	}
 
 	return 0;
 }
@@ -2096,8 +1961,6 @@ static void __exit xillybus_exit(void)
 {
 	/* flush_workqueue() was called for each endpoint released */
 	destroy_workqueue(xillybus_wq);
-
-	class_destroy(xillybus_class);
 }
 
 module_init(xillybus_init);