1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Driver for onboard USB hubs
  4 *
  5 * Copyright (c) 2022, Google LLC
  6 */
  7
  8#include <linux/device.h>
  9#include <linux/export.h>
 10#include <linux/gpio/consumer.h>
 11#include <linux/init.h>
 12#include <linux/kernel.h>
 13#include <linux/list.h>
 14#include <linux/module.h>
 15#include <linux/mutex.h>
 16#include <linux/of.h>
 17#include <linux/of_platform.h>
 18#include <linux/platform_device.h>
 19#include <linux/regulator/consumer.h>
 20#include <linux/slab.h>
 21#include <linux/suspend.h>
 22#include <linux/sysfs.h>
 23#include <linux/usb.h>
 24#include <linux/usb/hcd.h>
 25#include <linux/usb/onboard_hub.h>
 26#include <linux/workqueue.h>
 27
 28#include "onboard_usb_hub.h"
 29
 30static void onboard_hub_attach_usb_driver(struct work_struct *work);
 31
 32static struct usb_device_driver onboard_hub_usbdev_driver;
 33static DECLARE_WORK(attach_usb_driver_work, onboard_hub_attach_usb_driver);
 34
 35/************************** Platform driver **************************/
 36
 37struct usbdev_node {
 38	struct usb_device *udev;
 39	struct list_head list;
 40};
 41
 42struct onboard_hub {
 43	struct regulator *vdd;
 44	struct device *dev;
 45	const struct onboard_hub_pdata *pdata;
 46	struct gpio_desc *reset_gpio;
 47	bool always_powered_in_suspend;
 48	bool is_powered_on;
 49	bool going_away;
 50	struct list_head udev_list;
 51	struct mutex lock;
 52};
 53
 54static int onboard_hub_power_on(struct onboard_hub *hub)
 55{
 56	int err;
 57
 58	err = regulator_enable(hub->vdd);
 59	if (err) {
 60		dev_err(hub->dev, "failed to enable regulator: %d\n", err);
 61		return err;
 62	}
 63
 64	fsleep(hub->pdata->reset_us);
 65	gpiod_set_value_cansleep(hub->reset_gpio, 0);
 66
 67	hub->is_powered_on = true;
 68
 69	return 0;
 70}
 71
 72static int onboard_hub_power_off(struct onboard_hub *hub)
 73{
 74	int err;
 75
 76	gpiod_set_value_cansleep(hub->reset_gpio, 1);
 77
 78	err = regulator_disable(hub->vdd);
 79	if (err) {
 80		dev_err(hub->dev, "failed to disable regulator: %d\n", err);
 81		return err;
 82	}
 83
 84	hub->is_powered_on = false;
 85
 86	return 0;
 87}
 88
 89static int __maybe_unused onboard_hub_suspend(struct device *dev)
 90{
 91	struct onboard_hub *hub = dev_get_drvdata(dev);
 92	struct usbdev_node *node;
 93	bool power_off = true;
 94
 95	if (hub->always_powered_in_suspend)
 96		return 0;
 97
 98	mutex_lock(&hub->lock);
 99
100	list_for_each_entry(node, &hub->udev_list, list) {
101		if (!device_may_wakeup(node->udev->bus->controller))
102			continue;
103
104		if (usb_wakeup_enabled_descendants(node->udev)) {
105			power_off = false;
106			break;
107		}
108	}
109
110	mutex_unlock(&hub->lock);
111
112	if (!power_off)
113		return 0;
114
115	return onboard_hub_power_off(hub);
116}
117
118static int __maybe_unused onboard_hub_resume(struct device *dev)
119{
120	struct onboard_hub *hub = dev_get_drvdata(dev);
121
122	if (hub->is_powered_on)
123		return 0;
124
125	return onboard_hub_power_on(hub);
126}
127
128static inline void get_udev_link_name(const struct usb_device *udev, char *buf, size_t size)
129{
130	snprintf(buf, size, "usb_dev.%s", dev_name(&udev->dev));
131}
132
133static int onboard_hub_add_usbdev(struct onboard_hub *hub, struct usb_device *udev)
134{
135	struct usbdev_node *node;
136	char link_name[64];
137	int err;
138
139	mutex_lock(&hub->lock);
140
141	if (hub->going_away) {
142		err = -EINVAL;
143		goto error;
144	}
145
146	node = kzalloc(sizeof(*node), GFP_KERNEL);
147	if (!node) {
148		err = -ENOMEM;
149		goto error;
150	}
151
152	node->udev = udev;
153
154	list_add(&node->list, &hub->udev_list);
155
156	mutex_unlock(&hub->lock);
157
158	get_udev_link_name(udev, link_name, sizeof(link_name));
159	WARN_ON(sysfs_create_link(&hub->dev->kobj, &udev->dev.kobj, link_name));
160
161	return 0;
162
163error:
164	mutex_unlock(&hub->lock);
165
166	return err;
167}
168
169static void onboard_hub_remove_usbdev(struct onboard_hub *hub, const struct usb_device *udev)
170{
171	struct usbdev_node *node;
172	char link_name[64];
173
174	get_udev_link_name(udev, link_name, sizeof(link_name));
175	sysfs_remove_link(&hub->dev->kobj, link_name);
176
177	mutex_lock(&hub->lock);
178
179	list_for_each_entry(node, &hub->udev_list, list) {
180		if (node->udev == udev) {
181			list_del(&node->list);
182			kfree(node);
183			break;
184		}
185	}
186
187	mutex_unlock(&hub->lock);
188}
189
190static ssize_t always_powered_in_suspend_show(struct device *dev, struct device_attribute *attr,
191			   char *buf)
192{
193	const struct onboard_hub *hub = dev_get_drvdata(dev);
194
195	return sysfs_emit(buf, "%d\n", hub->always_powered_in_suspend);
196}
197
198static ssize_t always_powered_in_suspend_store(struct device *dev, struct device_attribute *attr,
199			    const char *buf, size_t count)
200{
201	struct onboard_hub *hub = dev_get_drvdata(dev);
202	bool val;
203	int ret;
204
205	ret = kstrtobool(buf, &val);
206	if (ret < 0)
207		return ret;
208
209	hub->always_powered_in_suspend = val;
210
211	return count;
212}
213static DEVICE_ATTR_RW(always_powered_in_suspend);
214
215static struct attribute *onboard_hub_attrs[] = {
216	&dev_attr_always_powered_in_suspend.attr,
217	NULL,
218};
219ATTRIBUTE_GROUPS(onboard_hub);
220
221static void onboard_hub_attach_usb_driver(struct work_struct *work)
222{
223	int err;
224
225	err = driver_attach(&onboard_hub_usbdev_driver.drvwrap.driver);
226	if (err)
227		pr_err("Failed to attach USB driver: %d\n", err);
228}
229
230static int onboard_hub_probe(struct platform_device *pdev)
231{
232	const struct of_device_id *of_id;
233	struct device *dev = &pdev->dev;
234	struct onboard_hub *hub;
235	int err;
236
237	hub = devm_kzalloc(dev, sizeof(*hub), GFP_KERNEL);
238	if (!hub)
239		return -ENOMEM;
240
241	of_id = of_match_device(onboard_hub_match, &pdev->dev);
242	if (!of_id)
243		return -ENODEV;
244
245	hub->pdata = of_id->data;
246	if (!hub->pdata)
247		return -EINVAL;
248
249	hub->vdd = devm_regulator_get(dev, "vdd");
250	if (IS_ERR(hub->vdd))
251		return PTR_ERR(hub->vdd);
252
253	hub->reset_gpio = devm_gpiod_get_optional(dev, "reset",
254						  GPIOD_OUT_HIGH);
255	if (IS_ERR(hub->reset_gpio))
256		return dev_err_probe(dev, PTR_ERR(hub->reset_gpio), "failed to get reset GPIO\n");
257
258	hub->dev = dev;
259	mutex_init(&hub->lock);
260	INIT_LIST_HEAD(&hub->udev_list);
261
262	dev_set_drvdata(dev, hub);
263
264	err = onboard_hub_power_on(hub);
265	if (err)
266		return err;
267
268	/*
269	 * The USB driver might have been detached from the USB devices by
270	 * onboard_hub_remove() (e.g. through an 'unbind' by userspace),
271	 * make sure to re-attach it if needed.
272	 *
273	 * This needs to be done deferred to avoid self-deadlocks on systems
274	 * with nested onboard hubs.
275	 */
276	schedule_work(&attach_usb_driver_work);
277
278	return 0;
279}
280
281static int onboard_hub_remove(struct platform_device *pdev)
282{
283	struct onboard_hub *hub = dev_get_drvdata(&pdev->dev);
284	struct usbdev_node *node;
285	struct usb_device *udev;
286
287	hub->going_away = true;
288
289	mutex_lock(&hub->lock);
290
291	/* unbind the USB devices to avoid dangling references to this device */
292	while (!list_empty(&hub->udev_list)) {
293		node = list_first_entry(&hub->udev_list, struct usbdev_node, list);
294		udev = node->udev;
295
296		/*
297		 * Unbinding the driver will call onboard_hub_remove_usbdev(),
298		 * which acquires hub->lock.  We must release the lock first.
299		 */
300		get_device(&udev->dev);
301		mutex_unlock(&hub->lock);
302		device_release_driver(&udev->dev);
303		put_device(&udev->dev);
304		mutex_lock(&hub->lock);
305	}
306
307	mutex_unlock(&hub->lock);
308
309	return onboard_hub_power_off(hub);
310}
311
312MODULE_DEVICE_TABLE(of, onboard_hub_match);
313
314static const struct dev_pm_ops __maybe_unused onboard_hub_pm_ops = {
315	SET_LATE_SYSTEM_SLEEP_PM_OPS(onboard_hub_suspend, onboard_hub_resume)
316};
317
318static struct platform_driver onboard_hub_driver = {
319	.probe = onboard_hub_probe,
320	.remove = onboard_hub_remove,
321
322	.driver = {
323		.name = "onboard-usb-hub",
324		.of_match_table = onboard_hub_match,
325		.pm = pm_ptr(&onboard_hub_pm_ops),
326		.dev_groups = onboard_hub_groups,
327	},
328};
329
330/************************** USB driver **************************/
331
332#define VENDOR_ID_GENESYS	0x05e3
333#define VENDOR_ID_MICROCHIP	0x0424
334#define VENDOR_ID_REALTEK	0x0bda
335#define VENDOR_ID_TI		0x0451
336
337/*
338 * Returns the onboard_hub platform device that is associated with the USB
339 * device passed as parameter.
340 */
341static struct onboard_hub *_find_onboard_hub(struct device *dev)
342{
343	struct platform_device *pdev;
344	struct device_node *np;
345	struct onboard_hub *hub;
346
347	pdev = of_find_device_by_node(dev->of_node);
348	if (!pdev) {
349		np = of_parse_phandle(dev->of_node, "peer-hub", 0);
350		if (!np) {
351			dev_err(dev, "failed to find device node for peer hub\n");
352			return ERR_PTR(-EINVAL);
353		}
354
355		pdev = of_find_device_by_node(np);
356		of_node_put(np);
357
358		if (!pdev)
359			return ERR_PTR(-ENODEV);
360	}
361
362	hub = dev_get_drvdata(&pdev->dev);
363	put_device(&pdev->dev);
364
365	/*
366	 * The presence of drvdata ('hub') indicates that the platform driver
367	 * finished probing. This handles the case where (conceivably) we could
368	 * be running at the exact same time as the platform driver's probe. If
369	 * we detect the race we request probe deferral and we'll come back and
370	 * try again.
371	 */
372	if (!hub)
373		return ERR_PTR(-EPROBE_DEFER);
374
375	return hub;
376}
377
378static int onboard_hub_usbdev_probe(struct usb_device *udev)
379{
380	struct device *dev = &udev->dev;
381	struct onboard_hub *hub;
382	int err;
383
384	/* ignore supported hubs without device tree node */
385	if (!dev->of_node)
386		return -ENODEV;
387
388	hub = _find_onboard_hub(dev);
389	if (IS_ERR(hub))
390		return PTR_ERR(hub);
391
392	dev_set_drvdata(dev, hub);
393
394	err = onboard_hub_add_usbdev(hub, udev);
395	if (err)
396		return err;
397
398	return 0;
399}
400
401static void onboard_hub_usbdev_disconnect(struct usb_device *udev)
402{
403	struct onboard_hub *hub = dev_get_drvdata(&udev->dev);
404
405	onboard_hub_remove_usbdev(hub, udev);
406}
407
408static const struct usb_device_id onboard_hub_id_table[] = {
409	{ USB_DEVICE(VENDOR_ID_GENESYS, 0x0608) }, /* Genesys Logic GL850G USB 2.0 */
410	{ USB_DEVICE(VENDOR_ID_MICROCHIP, 0x2514) }, /* USB2514B USB 2.0 */
411	{ USB_DEVICE(VENDOR_ID_REALTEK, 0x0411) }, /* RTS5411 USB 3.1 */
412	{ USB_DEVICE(VENDOR_ID_REALTEK, 0x5411) }, /* RTS5411 USB 2.1 */
413	{ USB_DEVICE(VENDOR_ID_REALTEK, 0x0414) }, /* RTS5414 USB 3.2 */
414	{ USB_DEVICE(VENDOR_ID_REALTEK, 0x5414) }, /* RTS5414 USB 2.1 */
415	{ USB_DEVICE(VENDOR_ID_TI, 0x8140) }, /* TI USB8041 3.0 */
416	{ USB_DEVICE(VENDOR_ID_TI, 0x8142) }, /* TI USB8041 2.0 */
417	{}
418};
419MODULE_DEVICE_TABLE(usb, onboard_hub_id_table);
420
421static struct usb_device_driver onboard_hub_usbdev_driver = {
422	.name = "onboard-usb-hub",
423	.probe = onboard_hub_usbdev_probe,
424	.disconnect = onboard_hub_usbdev_disconnect,
425	.generic_subclass = 1,
426	.supports_autosuspend =	1,
427	.id_table = onboard_hub_id_table,
428};
429
430static int __init onboard_hub_init(void)
431{
432	int ret;
433
434	ret = usb_register_device_driver(&onboard_hub_usbdev_driver, THIS_MODULE);
435	if (ret)
436		return ret;
437
438	ret = platform_driver_register(&onboard_hub_driver);
439	if (ret)
440		usb_deregister_device_driver(&onboard_hub_usbdev_driver);
441
442	return ret;
443}
444module_init(onboard_hub_init);
445
446static void __exit onboard_hub_exit(void)
447{
448	usb_deregister_device_driver(&onboard_hub_usbdev_driver);
449	platform_driver_unregister(&onboard_hub_driver);
450
451	cancel_work_sync(&attach_usb_driver_work);
452}
453module_exit(onboard_hub_exit);
454
455MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
456MODULE_DESCRIPTION("Driver for discrete onboard USB hubs");
457MODULE_LICENSE("GPL v2");