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1// SPDX-License-Identifier: GPL-2.0
2//
3// QiHeng Electronics ch341a USB-to-SPI adapter driver
4//
5// Copyright (C) 2024 Johannes Thumshirn <jth@kernel.org>
6//
7// Based on ch341a_spi.c from the flashrom project.
8
9#include <linux/module.h>
10#include <linux/usb.h>
11#include <linux/spi/spi.h>
12
13#define CH341_PACKET_LENGTH 32
14#define CH341_DEFAULT_TIMEOUT 1000
15
16#define CH341A_CMD_UIO_STREAM 0xab
17
18#define CH341A_CMD_UIO_STM_END 0x20
19#define CH341A_CMD_UIO_STM_DIR 0x40
20#define CH341A_CMD_UIO_STM_OUT 0x80
21
22#define CH341A_CMD_I2C_STREAM 0xaa
23#define CH341A_CMD_I2C_STM_SET 0x60
24#define CH341A_CMD_I2C_STM_END 0x00
25
26#define CH341A_CMD_SPI_STREAM 0xa8
27
28#define CH341A_STM_I2C_100K 0x01
29
30struct ch341_spi_dev {
31 struct spi_controller *ctrl;
32 struct usb_device *udev;
33 unsigned int write_pipe;
34 unsigned int read_pipe;
35 int rx_len;
36 void *rx_buf;
37 u8 *tx_buf;
38 struct urb *rx_urb;
39 struct spi_device *spidev;
40};
41
42static void ch341_set_cs(struct spi_device *spi, bool is_high)
43{
44 struct ch341_spi_dev *ch341 =
45 spi_controller_get_devdata(spi->controller);
46 int err;
47
48 memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
49 ch341->tx_buf[0] = CH341A_CMD_UIO_STREAM;
50 ch341->tx_buf[1] = CH341A_CMD_UIO_STM_OUT | (is_high ? 0x36 : 0x37);
51
52 if (is_high) {
53 ch341->tx_buf[2] = CH341A_CMD_UIO_STM_DIR | 0x3f;
54 ch341->tx_buf[3] = CH341A_CMD_UIO_STM_END;
55 } else {
56 ch341->tx_buf[2] = CH341A_CMD_UIO_STM_END;
57 }
58
59 err = usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf,
60 (is_high ? 4 : 3), NULL, CH341_DEFAULT_TIMEOUT);
61 if (err)
62 dev_err(&spi->dev,
63 "error sending USB message for setting CS (%d)\n", err);
64}
65
66static int ch341_transfer_one(struct spi_controller *host,
67 struct spi_device *spi,
68 struct spi_transfer *trans)
69{
70 struct ch341_spi_dev *ch341 =
71 spi_controller_get_devdata(spi->controller);
72 int len;
73 int ret;
74
75 len = min(CH341_PACKET_LENGTH, trans->len + 1);
76
77 memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
78
79 ch341->tx_buf[0] = CH341A_CMD_SPI_STREAM;
80
81 memcpy(ch341->tx_buf + 1, trans->tx_buf, len);
82
83 ret = usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf, len,
84 NULL, CH341_DEFAULT_TIMEOUT);
85 if (ret)
86 return ret;
87
88 return usb_bulk_msg(ch341->udev, ch341->read_pipe, trans->rx_buf,
89 len - 1, NULL, CH341_DEFAULT_TIMEOUT);
90}
91
92static void ch341_recv(struct urb *urb)
93{
94 struct ch341_spi_dev *ch341 = urb->context;
95 struct usb_device *udev = ch341->udev;
96
97 switch (urb->status) {
98 case 0:
99 /* success */
100 break;
101 case -ENOENT:
102 case -ECONNRESET:
103 case -EPIPE:
104 case -ESHUTDOWN:
105 dev_dbg(&udev->dev, "rx urb terminated with status: %d\n",
106 urb->status);
107 return;
108 default:
109 dev_dbg(&udev->dev, "rx urb error: %d\n", urb->status);
110 break;
111 }
112}
113
114static int ch341_config_stream(struct ch341_spi_dev *ch341)
115{
116 memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
117 ch341->tx_buf[0] = CH341A_CMD_I2C_STREAM;
118 ch341->tx_buf[1] = CH341A_CMD_I2C_STM_SET | CH341A_STM_I2C_100K;
119 ch341->tx_buf[2] = CH341A_CMD_I2C_STM_END;
120
121 return usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf, 3,
122 NULL, CH341_DEFAULT_TIMEOUT);
123}
124
125static int ch341_enable_pins(struct ch341_spi_dev *ch341, bool enable)
126{
127 memset(ch341->tx_buf, 0, CH341_PACKET_LENGTH);
128 ch341->tx_buf[0] = CH341A_CMD_UIO_STREAM;
129 ch341->tx_buf[1] = CH341A_CMD_UIO_STM_OUT | 0x37;
130 ch341->tx_buf[2] = CH341A_CMD_UIO_STM_DIR | (enable ? 0x3f : 0x00);
131 ch341->tx_buf[3] = CH341A_CMD_UIO_STM_END;
132
133 return usb_bulk_msg(ch341->udev, ch341->write_pipe, ch341->tx_buf, 4,
134 NULL, CH341_DEFAULT_TIMEOUT);
135}
136
137static struct spi_board_info chip = {
138 .modalias = "spi-ch341a",
139};
140
141static int ch341_probe(struct usb_interface *intf,
142 const struct usb_device_id *id)
143{
144 struct usb_device *udev = interface_to_usbdev(intf);
145 struct usb_endpoint_descriptor *in, *out;
146 struct ch341_spi_dev *ch341;
147 struct spi_controller *ctrl;
148 int ret;
149
150 ret = usb_find_common_endpoints(intf->cur_altsetting, &in, &out, NULL,
151 NULL);
152 if (ret)
153 return ret;
154
155 ctrl = devm_spi_alloc_host(&udev->dev, sizeof(struct ch341_spi_dev));
156 if (!ctrl)
157 return -ENOMEM;
158
159 ch341 = spi_controller_get_devdata(ctrl);
160 ch341->ctrl = ctrl;
161 ch341->udev = udev;
162 ch341->write_pipe = usb_sndbulkpipe(udev, usb_endpoint_num(out));
163 ch341->read_pipe = usb_rcvbulkpipe(udev, usb_endpoint_num(in));
164
165 ch341->rx_len = usb_endpoint_maxp(in);
166 ch341->rx_buf = devm_kzalloc(&udev->dev, ch341->rx_len, GFP_KERNEL);
167 if (!ch341->rx_buf)
168 return -ENOMEM;
169
170 ch341->rx_urb = usb_alloc_urb(0, GFP_KERNEL);
171 if (!ch341->rx_urb)
172 return -ENOMEM;
173
174 ch341->tx_buf =
175 devm_kzalloc(&udev->dev, CH341_PACKET_LENGTH, GFP_KERNEL);
176 if (!ch341->tx_buf)
177 return -ENOMEM;
178
179 usb_fill_bulk_urb(ch341->rx_urb, udev, ch341->read_pipe, ch341->rx_buf,
180 ch341->rx_len, ch341_recv, ch341);
181
182 ret = usb_submit_urb(ch341->rx_urb, GFP_KERNEL);
183 if (ret) {
184 usb_free_urb(ch341->rx_urb);
185 return -ENOMEM;
186 }
187
188 ctrl->bus_num = -1;
189 ctrl->mode_bits = SPI_CPHA;
190 ctrl->transfer_one = ch341_transfer_one;
191 ctrl->set_cs = ch341_set_cs;
192 ctrl->auto_runtime_pm = false;
193
194 usb_set_intfdata(intf, ch341);
195
196 ret = ch341_config_stream(ch341);
197 if (ret)
198 return ret;
199
200 ret = ch341_enable_pins(ch341, true);
201 if (ret)
202 return ret;
203
204 ret = spi_register_controller(ctrl);
205 if (ret)
206 return ret;
207
208 ch341->spidev = spi_new_device(ctrl, &chip);
209 if (!ch341->spidev)
210 return -ENOMEM;
211
212 return 0;
213}
214
215static void ch341_disconnect(struct usb_interface *intf)
216{
217 struct ch341_spi_dev *ch341 = usb_get_intfdata(intf);
218
219 spi_unregister_device(ch341->spidev);
220 spi_unregister_controller(ch341->ctrl);
221 ch341_enable_pins(ch341, false);
222 usb_free_urb(ch341->rx_urb);
223}
224
225static const struct usb_device_id ch341_id_table[] = {
226 { USB_DEVICE(0x1a86, 0x5512) },
227 { }
228};
229MODULE_DEVICE_TABLE(usb, ch341_id_table);
230
231static struct usb_driver ch341a_usb_driver = {
232 .name = "spi-ch341",
233 .probe = ch341_probe,
234 .disconnect = ch341_disconnect,
235 .id_table = ch341_id_table,
236};
237module_usb_driver(ch341a_usb_driver);
238
239MODULE_AUTHOR("Johannes Thumshirn <jth@kernel.org>");
240MODULE_DESCRIPTION("QiHeng Electronics ch341 USB2SPI");
241MODULE_LICENSE("GPL v2");