1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Tahvo USB transceiver driver
4  *
5  * Copyright (C) 2005-2006 Nokia Corporation
6  *
7  * Parts copied from isp1301_omap.c.
8  * Copyright (C) 2004 Texas Instruments
9  * Copyright (C) 2004 David Brownell
10  *
11  * Original driver written by Juha Yrjölä, Tony Lindgren and Timo Teräs.
12  * Modified for Retu/Tahvo MFD by Aaro Koskinen.
13  */
14 
15 #include <linux/io.h>
16 #include <linux/clk.h>
17 #include <linux/usb.h>
18 #include <linux/extcon-provider.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/usb/otg.h>
22 #include <linux/mfd/retu.h>
23 #include <linux/usb/gadget.h>
24 #include <linux/platform_device.h>
25 
26 #define DRIVER_NAME     "tahvo-usb"
27 
28 #define TAHVO_REG_IDSR	0x02
29 #define TAHVO_REG_USBR	0x06
30 
31 #define USBR_SLAVE_CONTROL	(1 << 8)
32 #define USBR_VPPVIO_SW		(1 << 7)
33 #define USBR_SPEED		(1 << 6)
34 #define USBR_REGOUT		(1 << 5)
35 #define USBR_MASTER_SW2		(1 << 4)
36 #define USBR_MASTER_SW1		(1 << 3)
37 #define USBR_SLAVE_SW		(1 << 2)
38 #define USBR_NSUSPEND		(1 << 1)
39 #define USBR_SEMODE		(1 << 0)
40 
41 #define TAHVO_MODE_HOST		0
42 #define TAHVO_MODE_PERIPHERAL	1
43 
44 struct tahvo_usb {
45 	struct platform_device	*pt_dev;
46 	struct usb_phy		phy;
47 	int			vbus_state;
48 	struct mutex		serialize;
49 	struct clk		*ick;
50 	int			irq;
51 	int			tahvo_mode;
52 	struct extcon_dev	*extcon;
53 };
54 
55 static const unsigned int tahvo_cable[] = {
56 	EXTCON_USB,
57 	EXTCON_USB_HOST,
58 
59 	EXTCON_NONE,
60 };
61 
vbus_show(struct device * device,struct device_attribute * attr,char * buf)62 static ssize_t vbus_show(struct device *device,
63 			       struct device_attribute *attr, char *buf)
64 {
65 	struct tahvo_usb *tu = dev_get_drvdata(device);
66 	return sprintf(buf, "%s\n", tu->vbus_state ? "on" : "off");
67 }
68 static DEVICE_ATTR_RO(vbus);
69 
check_vbus_state(struct tahvo_usb * tu)70 static void check_vbus_state(struct tahvo_usb *tu)
71 {
72 	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
73 	int reg, prev_state;
74 
75 	reg = retu_read(rdev, TAHVO_REG_IDSR);
76 	if (reg & TAHVO_STAT_VBUS) {
77 		switch (tu->phy.otg->state) {
78 		case OTG_STATE_B_IDLE:
79 			/* Enable the gadget driver */
80 			if (tu->phy.otg->gadget)
81 				usb_gadget_vbus_connect(tu->phy.otg->gadget);
82 			tu->phy.otg->state = OTG_STATE_B_PERIPHERAL;
83 			usb_phy_set_event(&tu->phy, USB_EVENT_ENUMERATED);
84 			break;
85 		case OTG_STATE_A_IDLE:
86 			/*
87 			 * Session is now valid assuming the USB hub is driving
88 			 * Vbus.
89 			 */
90 			tu->phy.otg->state = OTG_STATE_A_HOST;
91 			break;
92 		default:
93 			break;
94 		}
95 		dev_info(&tu->pt_dev->dev, "USB cable connected\n");
96 	} else {
97 		switch (tu->phy.otg->state) {
98 		case OTG_STATE_B_PERIPHERAL:
99 			if (tu->phy.otg->gadget)
100 				usb_gadget_vbus_disconnect(tu->phy.otg->gadget);
101 			tu->phy.otg->state = OTG_STATE_B_IDLE;
102 			usb_phy_set_event(&tu->phy, USB_EVENT_NONE);
103 			break;
104 		case OTG_STATE_A_HOST:
105 			tu->phy.otg->state = OTG_STATE_A_IDLE;
106 			break;
107 		default:
108 			break;
109 		}
110 		dev_info(&tu->pt_dev->dev, "USB cable disconnected\n");
111 	}
112 
113 	prev_state = tu->vbus_state;
114 	tu->vbus_state = reg & TAHVO_STAT_VBUS;
115 	if (prev_state != tu->vbus_state) {
116 		extcon_set_state_sync(tu->extcon, EXTCON_USB, tu->vbus_state);
117 		sysfs_notify(&tu->pt_dev->dev.kobj, NULL, "vbus_state");
118 	}
119 }
120 
tahvo_usb_become_host(struct tahvo_usb * tu)121 static void tahvo_usb_become_host(struct tahvo_usb *tu)
122 {
123 	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
124 
125 	extcon_set_state_sync(tu->extcon, EXTCON_USB_HOST, true);
126 
127 	/* Power up the transceiver in USB host mode */
128 	retu_write(rdev, TAHVO_REG_USBR, USBR_REGOUT | USBR_NSUSPEND |
129 		   USBR_MASTER_SW2 | USBR_MASTER_SW1);
130 	tu->phy.otg->state = OTG_STATE_A_IDLE;
131 
132 	check_vbus_state(tu);
133 }
134 
tahvo_usb_stop_host(struct tahvo_usb * tu)135 static void tahvo_usb_stop_host(struct tahvo_usb *tu)
136 {
137 	tu->phy.otg->state = OTG_STATE_A_IDLE;
138 }
139 
tahvo_usb_become_peripheral(struct tahvo_usb * tu)140 static void tahvo_usb_become_peripheral(struct tahvo_usb *tu)
141 {
142 	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
143 
144 	extcon_set_state_sync(tu->extcon, EXTCON_USB_HOST, false);
145 
146 	/* Power up transceiver and set it in USB peripheral mode */
147 	retu_write(rdev, TAHVO_REG_USBR, USBR_SLAVE_CONTROL | USBR_REGOUT |
148 		   USBR_NSUSPEND | USBR_SLAVE_SW);
149 	tu->phy.otg->state = OTG_STATE_B_IDLE;
150 
151 	check_vbus_state(tu);
152 }
153 
tahvo_usb_stop_peripheral(struct tahvo_usb * tu)154 static void tahvo_usb_stop_peripheral(struct tahvo_usb *tu)
155 {
156 	if (tu->phy.otg->gadget)
157 		usb_gadget_vbus_disconnect(tu->phy.otg->gadget);
158 	tu->phy.otg->state = OTG_STATE_B_IDLE;
159 }
160 
tahvo_usb_power_off(struct tahvo_usb * tu)161 static void tahvo_usb_power_off(struct tahvo_usb *tu)
162 {
163 	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
164 
165 	/* Disable gadget controller if any */
166 	if (tu->phy.otg->gadget)
167 		usb_gadget_vbus_disconnect(tu->phy.otg->gadget);
168 
169 	/* Power off transceiver */
170 	retu_write(rdev, TAHVO_REG_USBR, 0);
171 	tu->phy.otg->state = OTG_STATE_UNDEFINED;
172 }
173 
tahvo_usb_set_suspend(struct usb_phy * dev,int suspend)174 static int tahvo_usb_set_suspend(struct usb_phy *dev, int suspend)
175 {
176 	struct tahvo_usb *tu = container_of(dev, struct tahvo_usb, phy);
177 	struct retu_dev *rdev = dev_get_drvdata(tu->pt_dev->dev.parent);
178 	u16 w;
179 
180 	dev_dbg(&tu->pt_dev->dev, "%s\n", __func__);
181 
182 	w = retu_read(rdev, TAHVO_REG_USBR);
183 	if (suspend)
184 		w &= ~USBR_NSUSPEND;
185 	else
186 		w |= USBR_NSUSPEND;
187 	retu_write(rdev, TAHVO_REG_USBR, w);
188 
189 	return 0;
190 }
191 
tahvo_usb_set_host(struct usb_otg * otg,struct usb_bus * host)192 static int tahvo_usb_set_host(struct usb_otg *otg, struct usb_bus *host)
193 {
194 	struct tahvo_usb *tu = container_of(otg->usb_phy, struct tahvo_usb,
195 					    phy);
196 
197 	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, host);
198 
199 	mutex_lock(&tu->serialize);
200 
201 	if (host == NULL) {
202 		if (tu->tahvo_mode == TAHVO_MODE_HOST)
203 			tahvo_usb_power_off(tu);
204 		otg->host = NULL;
205 		mutex_unlock(&tu->serialize);
206 		return 0;
207 	}
208 
209 	if (tu->tahvo_mode == TAHVO_MODE_HOST) {
210 		otg->host = NULL;
211 		tahvo_usb_become_host(tu);
212 	}
213 
214 	otg->host = host;
215 
216 	mutex_unlock(&tu->serialize);
217 
218 	return 0;
219 }
220 
tahvo_usb_set_peripheral(struct usb_otg * otg,struct usb_gadget * gadget)221 static int tahvo_usb_set_peripheral(struct usb_otg *otg,
222 				    struct usb_gadget *gadget)
223 {
224 	struct tahvo_usb *tu = container_of(otg->usb_phy, struct tahvo_usb,
225 					    phy);
226 
227 	dev_dbg(&tu->pt_dev->dev, "%s %p\n", __func__, gadget);
228 
229 	mutex_lock(&tu->serialize);
230 
231 	if (!gadget) {
232 		if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
233 			tahvo_usb_power_off(tu);
234 		tu->phy.otg->gadget = NULL;
235 		mutex_unlock(&tu->serialize);
236 		return 0;
237 	}
238 
239 	tu->phy.otg->gadget = gadget;
240 	if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
241 		tahvo_usb_become_peripheral(tu);
242 
243 	mutex_unlock(&tu->serialize);
244 
245 	return 0;
246 }
247 
tahvo_usb_vbus_interrupt(int irq,void * _tu)248 static irqreturn_t tahvo_usb_vbus_interrupt(int irq, void *_tu)
249 {
250 	struct tahvo_usb *tu = _tu;
251 
252 	mutex_lock(&tu->serialize);
253 	check_vbus_state(tu);
254 	mutex_unlock(&tu->serialize);
255 
256 	return IRQ_HANDLED;
257 }
258 
otg_mode_show(struct device * device,struct device_attribute * attr,char * buf)259 static ssize_t otg_mode_show(struct device *device,
260 			     struct device_attribute *attr, char *buf)
261 {
262 	struct tahvo_usb *tu = dev_get_drvdata(device);
263 
264 	switch (tu->tahvo_mode) {
265 	case TAHVO_MODE_HOST:
266 		return sprintf(buf, "host\n");
267 	case TAHVO_MODE_PERIPHERAL:
268 		return sprintf(buf, "peripheral\n");
269 	}
270 
271 	return -EINVAL;
272 }
273 
otg_mode_store(struct device * device,struct device_attribute * attr,const char * buf,size_t count)274 static ssize_t otg_mode_store(struct device *device,
275 			      struct device_attribute *attr,
276 			      const char *buf, size_t count)
277 {
278 	struct tahvo_usb *tu = dev_get_drvdata(device);
279 	int r;
280 
281 	mutex_lock(&tu->serialize);
282 	if (count >= 4 && strncmp(buf, "host", 4) == 0) {
283 		if (tu->tahvo_mode == TAHVO_MODE_PERIPHERAL)
284 			tahvo_usb_stop_peripheral(tu);
285 		tu->tahvo_mode = TAHVO_MODE_HOST;
286 		if (tu->phy.otg->host) {
287 			dev_info(device, "HOST mode: host controller present\n");
288 			tahvo_usb_become_host(tu);
289 		} else {
290 			dev_info(device, "HOST mode: no host controller, powering off\n");
291 			tahvo_usb_power_off(tu);
292 		}
293 		r = strlen(buf);
294 	} else if (count >= 10 && strncmp(buf, "peripheral", 10) == 0) {
295 		if (tu->tahvo_mode == TAHVO_MODE_HOST)
296 			tahvo_usb_stop_host(tu);
297 		tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
298 		if (tu->phy.otg->gadget) {
299 			dev_info(device, "PERIPHERAL mode: gadget driver present\n");
300 			tahvo_usb_become_peripheral(tu);
301 		} else {
302 			dev_info(device, "PERIPHERAL mode: no gadget driver, powering off\n");
303 			tahvo_usb_power_off(tu);
304 		}
305 		r = strlen(buf);
306 	} else {
307 		r = -EINVAL;
308 	}
309 	mutex_unlock(&tu->serialize);
310 
311 	return r;
312 }
313 static DEVICE_ATTR_RW(otg_mode);
314 
315 static struct attribute *tahvo_attributes[] = {
316 	&dev_attr_vbus.attr,
317 	&dev_attr_otg_mode.attr,
318 	NULL
319 };
320 
321 static const struct attribute_group tahvo_attr_group = {
322 	.attrs = tahvo_attributes,
323 };
324 
tahvo_usb_probe(struct platform_device * pdev)325 static int tahvo_usb_probe(struct platform_device *pdev)
326 {
327 	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
328 	struct tahvo_usb *tu;
329 	int ret;
330 
331 	tu = devm_kzalloc(&pdev->dev, sizeof(*tu), GFP_KERNEL);
332 	if (!tu)
333 		return -ENOMEM;
334 
335 	tu->phy.otg = devm_kzalloc(&pdev->dev, sizeof(*tu->phy.otg),
336 				   GFP_KERNEL);
337 	if (!tu->phy.otg)
338 		return -ENOMEM;
339 
340 	tu->pt_dev = pdev;
341 
342 	/* Default mode */
343 #ifdef CONFIG_TAHVO_USB_HOST_BY_DEFAULT
344 	tu->tahvo_mode = TAHVO_MODE_HOST;
345 #else
346 	tu->tahvo_mode = TAHVO_MODE_PERIPHERAL;
347 #endif
348 
349 	mutex_init(&tu->serialize);
350 
351 	tu->ick = devm_clk_get(&pdev->dev, "usb_l4_ick");
352 	if (!IS_ERR(tu->ick))
353 		clk_enable(tu->ick);
354 
355 	/*
356 	 * Set initial state, so that we generate kevents only on state changes.
357 	 */
358 	tu->vbus_state = retu_read(rdev, TAHVO_REG_IDSR) & TAHVO_STAT_VBUS;
359 
360 	tu->extcon = devm_extcon_dev_allocate(&pdev->dev, tahvo_cable);
361 	if (IS_ERR(tu->extcon)) {
362 		dev_err(&pdev->dev, "failed to allocate memory for extcon\n");
363 		ret = PTR_ERR(tu->extcon);
364 		goto err_disable_clk;
365 	}
366 
367 	ret = devm_extcon_dev_register(&pdev->dev, tu->extcon);
368 	if (ret) {
369 		dev_err(&pdev->dev, "could not register extcon device: %d\n",
370 			ret);
371 		goto err_disable_clk;
372 	}
373 
374 	/* Set the initial cable state. */
375 	extcon_set_state_sync(tu->extcon, EXTCON_USB_HOST,
376 			       tu->tahvo_mode == TAHVO_MODE_HOST);
377 	extcon_set_state_sync(tu->extcon, EXTCON_USB, tu->vbus_state);
378 
379 	/* Create OTG interface */
380 	tahvo_usb_power_off(tu);
381 	tu->phy.dev = &pdev->dev;
382 	tu->phy.otg->state = OTG_STATE_UNDEFINED;
383 	tu->phy.label = DRIVER_NAME;
384 	tu->phy.set_suspend = tahvo_usb_set_suspend;
385 
386 	tu->phy.otg->usb_phy = &tu->phy;
387 	tu->phy.otg->set_host = tahvo_usb_set_host;
388 	tu->phy.otg->set_peripheral = tahvo_usb_set_peripheral;
389 
390 	ret = usb_add_phy(&tu->phy, USB_PHY_TYPE_USB2);
391 	if (ret < 0) {
392 		dev_err(&pdev->dev, "cannot register USB transceiver: %d\n",
393 			ret);
394 		goto err_disable_clk;
395 	}
396 
397 	dev_set_drvdata(&pdev->dev, tu);
398 
399 	tu->irq = platform_get_irq(pdev, 0);
400 	ret = request_threaded_irq(tu->irq, NULL, tahvo_usb_vbus_interrupt,
401 				   IRQF_ONESHOT,
402 				   "tahvo-vbus", tu);
403 	if (ret) {
404 		dev_err(&pdev->dev, "could not register tahvo-vbus irq: %d\n",
405 			ret);
406 		goto err_remove_phy;
407 	}
408 
409 	/* Attributes */
410 	ret = sysfs_create_group(&pdev->dev.kobj, &tahvo_attr_group);
411 	if (ret) {
412 		dev_err(&pdev->dev, "cannot create sysfs group: %d\n", ret);
413 		goto err_free_irq;
414 	}
415 
416 	return 0;
417 
418 err_free_irq:
419 	free_irq(tu->irq, tu);
420 err_remove_phy:
421 	usb_remove_phy(&tu->phy);
422 err_disable_clk:
423 	if (!IS_ERR(tu->ick))
424 		clk_disable(tu->ick);
425 
426 	return ret;
427 }
428 
tahvo_usb_remove(struct platform_device * pdev)429 static int tahvo_usb_remove(struct platform_device *pdev)
430 {
431 	struct tahvo_usb *tu = platform_get_drvdata(pdev);
432 
433 	sysfs_remove_group(&pdev->dev.kobj, &tahvo_attr_group);
434 	free_irq(tu->irq, tu);
435 	usb_remove_phy(&tu->phy);
436 	if (!IS_ERR(tu->ick))
437 		clk_disable(tu->ick);
438 
439 	return 0;
440 }
441 
442 static struct platform_driver tahvo_usb_driver = {
443 	.probe		= tahvo_usb_probe,
444 	.remove		= tahvo_usb_remove,
445 	.driver		= {
446 		.name	= "tahvo-usb",
447 	},
448 };
449 module_platform_driver(tahvo_usb_driver);
450 
451 MODULE_DESCRIPTION("Tahvo USB transceiver driver");
452 MODULE_LICENSE("GPL");
453 MODULE_AUTHOR("Juha Yrjölä, Tony Lindgren, and Timo Teräs");
454 MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
455