1// SPDX-License-Identifier: GPL-2.0+
2//
3// Copyright (C) 2018 Sean Young <sean@mess.org>
4
5#include <linux/module.h>
6#include <linux/usb.h>
7#include <linux/usb/input.h>
8#include <media/rc-core.h>
9
10/* Each bit is 250us */
11#define BIT_DURATION 250
12
13struct imon {
14	struct device *dev;
15	struct urb *ir_urb;
16	struct rc_dev *rcdev;
17	__be64 ir_buf;
18	char phys[64];
19};
20
21/*
22 * The first 5 bytes of data represent IR pulse or space. Each bit, starting
23 * from highest bit in the first byte, represents 250µs of data. It is 1
24 * for space and 0 for pulse.
25 *
26 * The station sends 10 packets, and the 7th byte will be number 1 to 10, so
27 * when we receive 10 we assume all the data has arrived.
28 */
29static void imon_ir_data(struct imon *imon)
30{
31	struct ir_raw_event rawir = {};
32	u64 data = be64_to_cpu(imon->ir_buf);
33	u8 packet_no = data & 0xff;
34	int offset = 40;
35	int bit;
36
37	if (packet_no == 0xff)
38		return;
39
40	dev_dbg(imon->dev, "data: %*ph", 8, &imon->ir_buf);
41
42	/*
43	 * Only the first 5 bytes contain IR data. Right shift so we move
44	 * the IR bits to the lower 40 bits.
45	 */
46	data >>= 24;
47
48	do {
49		/*
50		 * Find highest set bit which is less or equal to offset
51		 *
52		 * offset is the bit above (base 0) where we start looking.
53		 *
54		 * data & (BIT_ULL(offset) - 1) masks off any unwanted bits,
55		 * so we have just bits less than offset.
56		 *
57		 * fls will tell us the highest bit set plus 1 (or 0 if no
58		 * bits are set).
59		 */
60		rawir.pulse = !rawir.pulse;
61		bit = fls64(data & (BIT_ULL(offset) - 1));
62		if (bit < offset) {
63			dev_dbg(imon->dev, "%s: %d bits",
64				rawir.pulse ? "pulse" : "space", offset - bit);
65			rawir.duration = (offset - bit) * BIT_DURATION;
66			ir_raw_event_store_with_filter(imon->rcdev, &rawir);
67
68			offset = bit;
69		}
70
71		data = ~data;
72	} while (offset > 0);
73
74	if (packet_no == 0x0a && !imon->rcdev->idle) {
75		ir_raw_event_set_idle(imon->rcdev, true);
76		ir_raw_event_handle(imon->rcdev);
77	}
78}
79
80static void imon_ir_rx(struct urb *urb)
81{
82	struct imon *imon = urb->context;
83	int ret;
84
85	switch (urb->status) {
86	case 0:
87		imon_ir_data(imon);
88		break;
89	case -ECONNRESET:
90	case -ENOENT:
91	case -ESHUTDOWN:
92		usb_unlink_urb(urb);
93		return;
94	case -EPIPE:
95	default:
96		dev_dbg(imon->dev, "error: urb status = %d", urb->status);
97		break;
98	}
99
100	ret = usb_submit_urb(urb, GFP_ATOMIC);
101	if (ret && ret != -ENODEV)
102		dev_warn(imon->dev, "failed to resubmit urb: %d", ret);
103}
104
105static int imon_probe(struct usb_interface *intf,
106		      const struct usb_device_id *id)
107{
108	struct usb_endpoint_descriptor *ir_ep = NULL;
109	struct usb_host_interface *idesc;
110	struct usb_device *udev;
111	struct rc_dev *rcdev;
112	struct imon *imon;
113	int i, ret;
114
115	udev = interface_to_usbdev(intf);
116	idesc = intf->cur_altsetting;
117
118	for (i = 0; i < idesc->desc.bNumEndpoints; i++) {
119		struct usb_endpoint_descriptor *ep = &idesc->endpoint[i].desc;
120
121		if (usb_endpoint_is_int_in(ep)) {
122			ir_ep = ep;
123			break;
124		}
125	}
126
127	if (!ir_ep) {
128		dev_err(&intf->dev, "IR endpoint missing");
129		return -ENODEV;
130	}
131
132	imon = devm_kmalloc(&intf->dev, sizeof(*imon), GFP_KERNEL);
133	if (!imon)
134		return -ENOMEM;
135
136	imon->ir_urb = usb_alloc_urb(0, GFP_KERNEL);
137	if (!imon->ir_urb)
138		return -ENOMEM;
139
140	imon->dev = &intf->dev;
141	usb_fill_int_urb(imon->ir_urb, udev,
142			 usb_rcvintpipe(udev, ir_ep->bEndpointAddress),
143			 &imon->ir_buf, sizeof(imon->ir_buf),
144			 imon_ir_rx, imon, ir_ep->bInterval);
145
146	rcdev = devm_rc_allocate_device(&intf->dev, RC_DRIVER_IR_RAW);
147	if (!rcdev) {
148		ret = -ENOMEM;
149		goto free_urb;
150	}
151
152	usb_make_path(udev, imon->phys, sizeof(imon->phys));
153
154	rcdev->device_name = "iMON Station";
155	rcdev->driver_name = KBUILD_MODNAME;
156	rcdev->input_phys = imon->phys;
157	usb_to_input_id(udev, &rcdev->input_id);
158	rcdev->dev.parent = &intf->dev;
159	rcdev->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER;
160	rcdev->map_name = RC_MAP_IMON_RSC;
161	rcdev->rx_resolution = BIT_DURATION;
162	rcdev->priv = imon;
163
164	ret = devm_rc_register_device(&intf->dev, rcdev);
165	if (ret)
166		goto free_urb;
167
168	imon->rcdev = rcdev;
169
170	ret = usb_submit_urb(imon->ir_urb, GFP_KERNEL);
171	if (ret)
172		goto free_urb;
173
174	usb_set_intfdata(intf, imon);
175
176	return 0;
177
178free_urb:
179	usb_free_urb(imon->ir_urb);
180	return ret;
181}
182
183static void imon_disconnect(struct usb_interface *intf)
184{
185	struct imon *imon = usb_get_intfdata(intf);
186
187	usb_kill_urb(imon->ir_urb);
188	usb_free_urb(imon->ir_urb);
189}
190
191static const struct usb_device_id imon_table[] = {
192	/* SoundGraph iMON (IR only) -- sg_imon.inf */
193	{ USB_DEVICE(0x04e8, 0xff30) },
194	{}
195};
196
197static struct usb_driver imon_driver = {
198	.name = KBUILD_MODNAME,
199	.probe = imon_probe,
200	.disconnect = imon_disconnect,
201	.id_table = imon_table
202};
203
204module_usb_driver(imon_driver);
205
206MODULE_DESCRIPTION("Early raw iMON IR devices");
207MODULE_AUTHOR("Sean Young <sean@mess.org>");
208MODULE_LICENSE("GPL");
209MODULE_DEVICE_TABLE(usb, imon_table);
210