1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Generic USB GNSS receiver driver
  4 *
  5 * Copyright (C) 2021 Johan Hovold <johan@kernel.org>
  6 */
  7
  8#include <linux/errno.h>
  9#include <linux/gnss.h>
 10#include <linux/init.h>
 11#include <linux/kernel.h>
 12#include <linux/module.h>
 13#include <linux/slab.h>
 14#include <linux/usb.h>
 15
 16#define GNSS_USB_READ_BUF_LEN	512
 17#define GNSS_USB_WRITE_TIMEOUT	1000
 18
 19static const struct usb_device_id gnss_usb_id_table[] = {
 20	{ USB_DEVICE(0x1199, 0xb000) },		/* Sierra Wireless XM1210 */
 21	{ }
 22};
 23MODULE_DEVICE_TABLE(usb, gnss_usb_id_table);
 24
 25struct gnss_usb {
 26	struct usb_device *udev;
 27	struct usb_interface *intf;
 28	struct gnss_device *gdev;
 29	struct urb *read_urb;
 30	unsigned int write_pipe;
 31};
 32
 33static void gnss_usb_rx_complete(struct urb *urb)
 34{
 35	struct gnss_usb *gusb = urb->context;
 36	struct gnss_device *gdev = gusb->gdev;
 37	int status = urb->status;
 38	int len;
 39	int ret;
 40
 41	switch (status) {
 42	case 0:
 43		break;
 44	case -ENOENT:
 45	case -ECONNRESET:
 46	case -ESHUTDOWN:
 47		dev_dbg(&gdev->dev, "urb stopped: %d\n", status);
 48		return;
 49	case -EPIPE:
 50		dev_err(&gdev->dev, "urb stopped: %d\n", status);
 51		return;
 52	default:
 53		dev_dbg(&gdev->dev, "nonzero urb status: %d\n", status);
 54		goto resubmit;
 55	}
 56
 57	len = urb->actual_length;
 58	if (len == 0)
 59		goto resubmit;
 60
 61	ret = gnss_insert_raw(gdev, urb->transfer_buffer, len);
 62	if (ret < len)
 63		dev_dbg(&gdev->dev, "dropped %d bytes\n", len - ret);
 64resubmit:
 65	ret = usb_submit_urb(urb, GFP_ATOMIC);
 66	if (ret && ret != -EPERM && ret != -ENODEV)
 67		dev_err(&gdev->dev, "failed to resubmit urb: %d\n", ret);
 68}
 69
 70static int gnss_usb_open(struct gnss_device *gdev)
 71{
 72	struct gnss_usb *gusb = gnss_get_drvdata(gdev);
 73	int ret;
 74
 75	ret = usb_submit_urb(gusb->read_urb, GFP_KERNEL);
 76	if (ret) {
 77		if (ret != -EPERM && ret != -ENODEV)
 78			dev_err(&gdev->dev, "failed to submit urb: %d\n", ret);
 79		return ret;
 80	}
 81
 82	return 0;
 83}
 84
 85static void gnss_usb_close(struct gnss_device *gdev)
 86{
 87	struct gnss_usb *gusb = gnss_get_drvdata(gdev);
 88
 89	usb_kill_urb(gusb->read_urb);
 90}
 91
 92static int gnss_usb_write_raw(struct gnss_device *gdev,
 93		const unsigned char *buf, size_t count)
 94{
 95	struct gnss_usb *gusb = gnss_get_drvdata(gdev);
 96	void *tbuf;
 97	int ret;
 98
 99	tbuf = kmemdup(buf, count, GFP_KERNEL);
100	if (!tbuf)
101		return -ENOMEM;
102
103	ret = usb_bulk_msg(gusb->udev, gusb->write_pipe, tbuf, count, NULL,
104			GNSS_USB_WRITE_TIMEOUT);
105	kfree(tbuf);
106	if (ret)
107		return ret;
108
109	return count;
110}
111
112static const struct gnss_operations gnss_usb_gnss_ops = {
113	.open		= gnss_usb_open,
114	.close		= gnss_usb_close,
115	.write_raw	= gnss_usb_write_raw,
116};
117
118static int gnss_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
119{
120	struct usb_device *udev = interface_to_usbdev(intf);
121	struct usb_endpoint_descriptor *in, *out;
122	struct gnss_device *gdev;
123	struct gnss_usb *gusb;
124	struct urb *urb;
125	size_t buf_len;
126	void *buf;
127	int ret;
128
129	ret = usb_find_common_endpoints(intf->cur_altsetting, &in, &out, NULL,
130			NULL);
131	if (ret)
132		return ret;
133
134	gusb = kzalloc(sizeof(*gusb), GFP_KERNEL);
135	if (!gusb)
136		return -ENOMEM;
137
138	gdev = gnss_allocate_device(&intf->dev);
139	if (!gdev) {
140		ret = -ENOMEM;
141		goto err_free_gusb;
142	}
143
144	gdev->ops = &gnss_usb_gnss_ops;
145	gdev->type = GNSS_TYPE_NMEA;
146	gnss_set_drvdata(gdev, gusb);
147
148	urb = usb_alloc_urb(0, GFP_KERNEL);
149	if (!urb) {
150		ret = -ENOMEM;
151		goto err_put_gdev;
152	}
153
154	buf_len = max(usb_endpoint_maxp(in), GNSS_USB_READ_BUF_LEN);
155
156	buf = kzalloc(buf_len, GFP_KERNEL);
157	if (!buf) {
158		ret = -ENOMEM;
159		goto err_free_urb;
160	}
161
162	usb_fill_bulk_urb(urb, udev,
163			usb_rcvbulkpipe(udev, usb_endpoint_num(in)),
164			buf, buf_len, gnss_usb_rx_complete, gusb);
165
166	gusb->intf = intf;
167	gusb->udev = udev;
168	gusb->gdev = gdev;
169	gusb->read_urb = urb;
170	gusb->write_pipe = usb_sndbulkpipe(udev, usb_endpoint_num(out));
171
172	ret = gnss_register_device(gdev);
173	if (ret)
174		goto err_free_buf;
175
176	usb_set_intfdata(intf, gusb);
177
178	return 0;
179
180err_free_buf:
181	kfree(buf);
182err_free_urb:
183	usb_free_urb(urb);
184err_put_gdev:
185	gnss_put_device(gdev);
186err_free_gusb:
187	kfree(gusb);
188
189	return ret;
190}
191
192static void gnss_usb_disconnect(struct usb_interface *intf)
193{
194	struct gnss_usb *gusb = usb_get_intfdata(intf);
195
196	gnss_deregister_device(gusb->gdev);
197
198	kfree(gusb->read_urb->transfer_buffer);
199	usb_free_urb(gusb->read_urb);
200	gnss_put_device(gusb->gdev);
201	kfree(gusb);
202}
203
204static struct usb_driver gnss_usb_driver = {
205	.name		= "gnss-usb",
206	.probe		= gnss_usb_probe,
207	.disconnect	= gnss_usb_disconnect,
208	.id_table	= gnss_usb_id_table,
209};
210module_usb_driver(gnss_usb_driver);
211
212MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
213MODULE_DESCRIPTION("Generic USB GNSS receiver driver");
214MODULE_LICENSE("GPL v2");