xref: /linux/drivers/accel/drm_accel.c (revision 5027ec19f1049a07df5b0a37b1f462514cf2724b)
1 // SPDX-License-Identifier: GPL-2.0
2 
3 /*
4  * Copyright 2022 HabanaLabs, Ltd.
5  * All Rights Reserved.
6  *
7  */
8 
9 #include <linux/debugfs.h>
10 #include <linux/device.h>
11 #include <linux/idr.h>
12 
13 #include <drm/drm_accel.h>
14 #include <drm/drm_debugfs.h>
15 #include <drm/drm_drv.h>
16 #include <drm/drm_file.h>
17 #include <drm/drm_ioctl.h>
18 #include <drm/drm_print.h>
19 
20 static DEFINE_SPINLOCK(accel_minor_lock);
21 static struct idr accel_minors_idr;
22 
23 static struct dentry *accel_debugfs_root;
24 
25 static struct device_type accel_sysfs_device_minor = {
26 	.name = "accel_minor"
27 };
28 
29 static char *accel_devnode(const struct device *dev, umode_t *mode)
30 {
31 	return kasprintf(GFP_KERNEL, "accel/%s", dev_name(dev));
32 }
33 
34 static const struct class accel_class = {
35 	.name = "accel",
36 	.devnode = accel_devnode,
37 };
38 
39 static int accel_sysfs_init(void)
40 {
41 	return class_register(&accel_class);
42 }
43 
44 static void accel_sysfs_destroy(void)
45 {
46 	class_unregister(&accel_class);
47 }
48 
49 static int accel_name_info(struct seq_file *m, void *data)
50 {
51 	struct drm_info_node *node = (struct drm_info_node *) m->private;
52 	struct drm_minor *minor = node->minor;
53 	struct drm_device *dev = minor->dev;
54 	struct drm_master *master;
55 
56 	mutex_lock(&dev->master_mutex);
57 	master = dev->master;
58 	seq_printf(m, "%s", dev->driver->name);
59 	if (dev->dev)
60 		seq_printf(m, " dev=%s", dev_name(dev->dev));
61 	if (master && master->unique)
62 		seq_printf(m, " master=%s", master->unique);
63 	if (dev->unique)
64 		seq_printf(m, " unique=%s", dev->unique);
65 	seq_puts(m, "\n");
66 	mutex_unlock(&dev->master_mutex);
67 
68 	return 0;
69 }
70 
71 static const struct drm_info_list accel_debugfs_list[] = {
72 	{"name", accel_name_info, 0}
73 };
74 #define ACCEL_DEBUGFS_ENTRIES ARRAY_SIZE(accel_debugfs_list)
75 
76 /**
77  * accel_debugfs_init() - Initialize debugfs for device
78  * @dev: Pointer to the device instance.
79  *
80  * This function creates a root directory for the device in debugfs.
81  */
82 void accel_debugfs_init(struct drm_device *dev)
83 {
84 	drm_debugfs_dev_init(dev, accel_debugfs_root);
85 }
86 
87 /**
88  * accel_debugfs_register() - Register debugfs for device
89  * @dev: Pointer to the device instance.
90  *
91  * Creates common files for accelerators.
92  */
93 void accel_debugfs_register(struct drm_device *dev)
94 {
95 	struct drm_minor *minor = dev->accel;
96 
97 	minor->debugfs_root = dev->debugfs_root;
98 
99 	drm_debugfs_create_files(accel_debugfs_list, ACCEL_DEBUGFS_ENTRIES,
100 				 dev->debugfs_root, minor);
101 }
102 
103 /**
104  * accel_set_device_instance_params() - Set some device parameters for accel device
105  * @kdev: Pointer to the device instance.
106  * @index: The minor's index
107  *
108  * This function creates the dev_t of the device using the accel major and
109  * the device's minor number. In addition, it sets the class and type of the
110  * device instance to the accel sysfs class and device type, respectively.
111  */
112 void accel_set_device_instance_params(struct device *kdev, int index)
113 {
114 	kdev->devt = MKDEV(ACCEL_MAJOR, index);
115 	kdev->class = &accel_class;
116 	kdev->type = &accel_sysfs_device_minor;
117 }
118 
119 /**
120  * accel_minor_alloc() - Allocates a new accel minor
121  *
122  * This function access the accel minors idr and allocates from it
123  * a new id to represent a new accel minor
124  *
125  * Return: A new id on success or error code in case idr_alloc failed
126  */
127 int accel_minor_alloc(void)
128 {
129 	unsigned long flags;
130 	int r;
131 
132 	spin_lock_irqsave(&accel_minor_lock, flags);
133 	r = idr_alloc(&accel_minors_idr, NULL, 0, ACCEL_MAX_MINORS, GFP_NOWAIT);
134 	spin_unlock_irqrestore(&accel_minor_lock, flags);
135 
136 	return r;
137 }
138 
139 /**
140  * accel_minor_remove() - Remove an accel minor
141  * @index: The minor id to remove.
142  *
143  * This function access the accel minors idr and removes from
144  * it the member with the id that is passed to this function.
145  */
146 void accel_minor_remove(int index)
147 {
148 	unsigned long flags;
149 
150 	spin_lock_irqsave(&accel_minor_lock, flags);
151 	idr_remove(&accel_minors_idr, index);
152 	spin_unlock_irqrestore(&accel_minor_lock, flags);
153 }
154 
155 /**
156  * accel_minor_replace() - Replace minor pointer in accel minors idr.
157  * @minor: Pointer to the new minor.
158  * @index: The minor id to replace.
159  *
160  * This function access the accel minors idr structure and replaces the pointer
161  * that is associated with an existing id. Because the minor pointer can be
162  * NULL, we need to explicitly pass the index.
163  *
164  * Return: 0 for success, negative value for error
165  */
166 void accel_minor_replace(struct drm_minor *minor, int index)
167 {
168 	unsigned long flags;
169 
170 	spin_lock_irqsave(&accel_minor_lock, flags);
171 	idr_replace(&accel_minors_idr, minor, index);
172 	spin_unlock_irqrestore(&accel_minor_lock, flags);
173 }
174 
175 /*
176  * Looks up the given minor-ID and returns the respective DRM-minor object. The
177  * refence-count of the underlying device is increased so you must release this
178  * object with accel_minor_release().
179  *
180  * The object can be only a drm_minor that represents an accel device.
181  *
182  * As long as you hold this minor, it is guaranteed that the object and the
183  * minor->dev pointer will stay valid! However, the device may get unplugged and
184  * unregistered while you hold the minor.
185  */
186 static struct drm_minor *accel_minor_acquire(unsigned int minor_id)
187 {
188 	struct drm_minor *minor;
189 	unsigned long flags;
190 
191 	spin_lock_irqsave(&accel_minor_lock, flags);
192 	minor = idr_find(&accel_minors_idr, minor_id);
193 	if (minor)
194 		drm_dev_get(minor->dev);
195 	spin_unlock_irqrestore(&accel_minor_lock, flags);
196 
197 	if (!minor) {
198 		return ERR_PTR(-ENODEV);
199 	} else if (drm_dev_is_unplugged(minor->dev)) {
200 		drm_dev_put(minor->dev);
201 		return ERR_PTR(-ENODEV);
202 	}
203 
204 	return minor;
205 }
206 
207 static void accel_minor_release(struct drm_minor *minor)
208 {
209 	drm_dev_put(minor->dev);
210 }
211 
212 /**
213  * accel_open - open method for ACCEL file
214  * @inode: device inode
215  * @filp: file pointer.
216  *
217  * This function must be used by drivers as their &file_operations.open method.
218  * It looks up the correct ACCEL device and instantiates all the per-file
219  * resources for it. It also calls the &drm_driver.open driver callback.
220  *
221  * Return: 0 on success or negative errno value on failure.
222  */
223 int accel_open(struct inode *inode, struct file *filp)
224 {
225 	struct drm_device *dev;
226 	struct drm_minor *minor;
227 	int retcode;
228 
229 	minor = accel_minor_acquire(iminor(inode));
230 	if (IS_ERR(minor))
231 		return PTR_ERR(minor);
232 
233 	dev = minor->dev;
234 
235 	atomic_fetch_inc(&dev->open_count);
236 
237 	/* share address_space across all char-devs of a single device */
238 	filp->f_mapping = dev->anon_inode->i_mapping;
239 
240 	retcode = drm_open_helper(filp, minor);
241 	if (retcode)
242 		goto err_undo;
243 
244 	return 0;
245 
246 err_undo:
247 	atomic_dec(&dev->open_count);
248 	accel_minor_release(minor);
249 	return retcode;
250 }
251 EXPORT_SYMBOL_GPL(accel_open);
252 
253 static int accel_stub_open(struct inode *inode, struct file *filp)
254 {
255 	const struct file_operations *new_fops;
256 	struct drm_minor *minor;
257 	int err;
258 
259 	minor = accel_minor_acquire(iminor(inode));
260 	if (IS_ERR(minor))
261 		return PTR_ERR(minor);
262 
263 	new_fops = fops_get(minor->dev->driver->fops);
264 	if (!new_fops) {
265 		err = -ENODEV;
266 		goto out;
267 	}
268 
269 	replace_fops(filp, new_fops);
270 	if (filp->f_op->open)
271 		err = filp->f_op->open(inode, filp);
272 	else
273 		err = 0;
274 
275 out:
276 	accel_minor_release(minor);
277 
278 	return err;
279 }
280 
281 static const struct file_operations accel_stub_fops = {
282 	.owner = THIS_MODULE,
283 	.open = accel_stub_open,
284 	.llseek = noop_llseek,
285 };
286 
287 void accel_core_exit(void)
288 {
289 	unregister_chrdev(ACCEL_MAJOR, "accel");
290 	debugfs_remove(accel_debugfs_root);
291 	accel_sysfs_destroy();
292 	idr_destroy(&accel_minors_idr);
293 }
294 
295 int __init accel_core_init(void)
296 {
297 	int ret;
298 
299 	idr_init(&accel_minors_idr);
300 
301 	ret = accel_sysfs_init();
302 	if (ret < 0) {
303 		DRM_ERROR("Cannot create ACCEL class: %d\n", ret);
304 		goto error;
305 	}
306 
307 	accel_debugfs_root = debugfs_create_dir("accel", NULL);
308 
309 	ret = register_chrdev(ACCEL_MAJOR, "accel", &accel_stub_fops);
310 	if (ret < 0)
311 		DRM_ERROR("Cannot register ACCEL major: %d\n", ret);
312 
313 error:
314 	/*
315 	 * Any cleanup due to errors will be done in drm_core_exit() that
316 	 * will call accel_core_exit()
317 	 */
318 	return ret;
319 }
320