1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * MCP2200 - Microchip USB to GPIO bridge
4 *
5 * Copyright (c) 2023, Johannes Roith <johannes@gnu-linux.rocks>
6 *
7 * Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22228A.pdf
8 * App Note for HID: https://ww1.microchip.com/downloads/en/DeviceDoc/93066A.pdf
9 */
10#include <linux/completion.h>
11#include <linux/delay.h>
12#include <linux/err.h>
13#include <linux/gpio/driver.h>
14#include <linux/hid.h>
15#include <linux/hidraw.h>
16#include <linux/module.h>
17#include <linux/mutex.h>
18#include "hid-ids.h"
19
20/* Commands codes in a raw output report */
21#define SET_CLEAR_OUTPUTS 0x08
22#define CONFIGURE 0x10
23#define READ_EE 0x20
24#define WRITE_EE 0x40
25#define READ_ALL 0x80
26
27/* MCP GPIO direction encoding */
28enum MCP_IO_DIR {
29 MCP2200_DIR_OUT = 0x00,
30 MCP2200_DIR_IN = 0x01,
31};
32
33/* Altternative pin assignments */
34#define TXLED 2
35#define RXLED 3
36#define USBCFG 6
37#define SSPND 7
38#define MCP_NGPIO 8
39
40/* CMD to set or clear a GPIO output */
41struct mcp_set_clear_outputs {
42 u8 cmd;
43 u8 dummys1[10];
44 u8 set_bmap;
45 u8 clear_bmap;
46 u8 dummys2[3];
47} __packed;
48
49/* CMD to configure the IOs */
50struct mcp_configure {
51 u8 cmd;
52 u8 dummys1[3];
53 u8 io_bmap;
54 u8 config_alt_pins;
55 u8 io_default_val_bmap;
56 u8 config_alt_options;
57 u8 baud_h;
58 u8 baud_l;
59 u8 dummys2[6];
60} __packed;
61
62/* CMD to read all parameters */
63struct mcp_read_all {
64 u8 cmd;
65 u8 dummys[15];
66} __packed;
67
68/* Response to the read all cmd */
69struct mcp_read_all_resp {
70 u8 cmd;
71 u8 eep_addr;
72 u8 dummy;
73 u8 eep_val;
74 u8 io_bmap;
75 u8 config_alt_pins;
76 u8 io_default_val_bmap;
77 u8 config_alt_options;
78 u8 baud_h;
79 u8 baud_l;
80 u8 io_port_val_bmap;
81 u8 dummys[5];
82} __packed;
83
84struct mcp2200 {
85 struct hid_device *hdev;
86 struct mutex lock;
87 struct completion wait_in_report;
88 u8 gpio_dir;
89 u8 gpio_val;
90 u8 gpio_inval;
91 u8 baud_h;
92 u8 baud_l;
93 u8 config_alt_pins;
94 u8 gpio_reset_val;
95 u8 config_alt_options;
96 int status;
97 struct gpio_chip gc;
98 u8 hid_report[16];
99};
100
101/* this executes the READ_ALL cmd */
102static int mcp_cmd_read_all(struct mcp2200 *mcp)
103{
104 struct mcp_read_all *read_all;
105 int len, t;
106
107 reinit_completion(x: &mcp->wait_in_report);
108
109 mutex_lock(&mcp->lock);
110
111 read_all = (struct mcp_read_all *) mcp->hid_report;
112 read_all->cmd = READ_ALL;
113 len = hid_hw_output_report(hdev: mcp->hdev, buf: (u8 *) read_all,
114 len: sizeof(struct mcp_read_all));
115
116 mutex_unlock(lock: &mcp->lock);
117
118 if (len != sizeof(struct mcp_read_all))
119 return -EINVAL;
120
121 t = wait_for_completion_timeout(x: &mcp->wait_in_report,
122 timeout: msecs_to_jiffies(m: 4000));
123 if (!t)
124 return -ETIMEDOUT;
125
126 /* return status, negative value if wrong response was received */
127 return mcp->status;
128}
129
130static int mcp_set_multiple(struct gpio_chip *gc, unsigned long *mask,
131 unsigned long *bits)
132{
133 struct mcp2200 *mcp = gpiochip_get_data(gc);
134 u8 value;
135 int status;
136 struct mcp_set_clear_outputs *cmd;
137
138 mutex_lock(&mcp->lock);
139 cmd = (struct mcp_set_clear_outputs *) mcp->hid_report;
140
141 value = mcp->gpio_val & ~*mask;
142 value |= (*mask & *bits);
143
144 cmd->cmd = SET_CLEAR_OUTPUTS;
145 cmd->set_bmap = value;
146 cmd->clear_bmap = ~(value);
147
148 status = hid_hw_output_report(hdev: mcp->hdev, buf: (u8 *) cmd,
149 len: sizeof(struct mcp_set_clear_outputs));
150
151 if (status == sizeof(struct mcp_set_clear_outputs))
152 mcp->gpio_val = value;
153 else
154 status = -EIO;
155
156 mutex_unlock(lock: &mcp->lock);
157
158 return status;
159}
160
161static int mcp_set(struct gpio_chip *gc, unsigned int gpio_nr, int value)
162{
163 unsigned long mask = 1 << gpio_nr;
164 unsigned long bmap_value = value << gpio_nr;
165
166 return mcp_set_multiple(gc, mask: &mask, bits: &bmap_value);
167}
168
169static int mcp_get_multiple(struct gpio_chip *gc, unsigned long *mask,
170 unsigned long *bits)
171{
172 u32 val;
173 struct mcp2200 *mcp = gpiochip_get_data(gc);
174 int status;
175
176 status = mcp_cmd_read_all(mcp);
177 if (status)
178 return status;
179
180 val = mcp->gpio_inval;
181 *bits = (val & *mask);
182 return 0;
183}
184
185static int mcp_get(struct gpio_chip *gc, unsigned int gpio_nr)
186{
187 unsigned long mask = 0, bits = 0;
188
189 mask = (1 << gpio_nr);
190 mcp_get_multiple(gc, mask: &mask, bits: &bits);
191 return bits > 0;
192}
193
194static int mcp_get_direction(struct gpio_chip *gc, unsigned int gpio_nr)
195{
196 struct mcp2200 *mcp = gpiochip_get_data(gc);
197
198 return (mcp->gpio_dir & (MCP2200_DIR_IN << gpio_nr))
199 ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
200}
201
202static int mcp_set_direction(struct gpio_chip *gc, unsigned int gpio_nr,
203 enum MCP_IO_DIR io_direction)
204{
205 struct mcp2200 *mcp = gpiochip_get_data(gc);
206 struct mcp_configure *conf;
207 int status;
208 /* after the configure cmd we will need to set the outputs again */
209 unsigned long mask = ~(mcp->gpio_dir); /* only set outputs */
210 unsigned long bits = mcp->gpio_val;
211 /* Offsets of alternative pins in config_alt_pins, 0 is not used */
212 u8 alt_pin_conf[8] = {SSPND, USBCFG, 0, 0, 0, 0, RXLED, TXLED};
213 u8 config_alt_pins = mcp->config_alt_pins;
214
215 /* Read in the reset baudrate first, we need it later */
216 status = mcp_cmd_read_all(mcp);
217 if (status != 0)
218 return status;
219
220 mutex_lock(&mcp->lock);
221 conf = (struct mcp_configure *) mcp->hid_report;
222
223 /* configure will reset the chip! */
224 conf->cmd = CONFIGURE;
225 conf->io_bmap = (mcp->gpio_dir & ~(1 << gpio_nr))
226 | (io_direction << gpio_nr);
227 /* Don't overwrite the reset parameters */
228 conf->baud_h = mcp->baud_h;
229 conf->baud_l = mcp->baud_l;
230 conf->config_alt_options = mcp->config_alt_options;
231 conf->io_default_val_bmap = mcp->gpio_reset_val;
232 /* Adjust alt. func if necessary */
233 if (alt_pin_conf[gpio_nr])
234 config_alt_pins &= ~(1 << alt_pin_conf[gpio_nr]);
235 conf->config_alt_pins = config_alt_pins;
236
237 status = hid_hw_output_report(hdev: mcp->hdev, buf: (u8 *) conf,
238 len: sizeof(struct mcp_set_clear_outputs));
239
240 if (status == sizeof(struct mcp_set_clear_outputs)) {
241 mcp->gpio_dir = conf->io_bmap;
242 mcp->config_alt_pins = config_alt_pins;
243 } else {
244 mutex_unlock(lock: &mcp->lock);
245 return -EIO;
246 }
247
248 mutex_unlock(lock: &mcp->lock);
249
250 /* Configure CMD will clear all IOs -> rewrite them */
251 mcp_set_multiple(gc, mask: &mask, bits: &bits);
252 return 0;
253}
254
255static int mcp_direction_input(struct gpio_chip *gc, unsigned int gpio_nr)
256{
257 return mcp_set_direction(gc, gpio_nr, io_direction: MCP2200_DIR_IN);
258}
259
260static int mcp_direction_output(struct gpio_chip *gc, unsigned int gpio_nr,
261 int value)
262{
263 int ret;
264 unsigned long mask, bmap_value;
265
266 mask = 1 << gpio_nr;
267 bmap_value = value << gpio_nr;
268
269 ret = mcp_set_direction(gc, gpio_nr, io_direction: MCP2200_DIR_OUT);
270 if (ret)
271 return ret;
272
273 return mcp_set_multiple(gc, mask: &mask, bits: &bmap_value);
274}
275
276static const struct gpio_chip template_chip = {
277 .label = "mcp2200",
278 .owner = THIS_MODULE,
279 .get_direction = mcp_get_direction,
280 .direction_input = mcp_direction_input,
281 .direction_output = mcp_direction_output,
282 .set_rv = mcp_set,
283 .set_multiple_rv = mcp_set_multiple,
284 .get = mcp_get,
285 .get_multiple = mcp_get_multiple,
286 .base = -1,
287 .ngpio = MCP_NGPIO,
288 .can_sleep = true,
289};
290
291/*
292 * MCP2200 uses interrupt endpoint for input reports. This function
293 * is called by HID layer when it receives i/p report from mcp2200,
294 * which is actually a response to the previously sent command.
295 */
296static int mcp2200_raw_event(struct hid_device *hdev, struct hid_report *report,
297 u8 *data, int size)
298{
299 struct mcp2200 *mcp = hid_get_drvdata(hdev);
300 struct mcp_read_all_resp *all_resp;
301
302 switch (data[0]) {
303 case READ_ALL:
304 all_resp = (struct mcp_read_all_resp *) data;
305 mcp->status = 0;
306 mcp->gpio_inval = all_resp->io_port_val_bmap;
307 mcp->baud_h = all_resp->baud_h;
308 mcp->baud_l = all_resp->baud_l;
309 mcp->gpio_reset_val = all_resp->io_default_val_bmap;
310 mcp->config_alt_pins = all_resp->config_alt_pins;
311 mcp->config_alt_options = all_resp->config_alt_options;
312 break;
313 default:
314 mcp->status = -EIO;
315 break;
316 }
317
318 complete(&mcp->wait_in_report);
319 return 0;
320}
321
322static int mcp2200_probe(struct hid_device *hdev, const struct hid_device_id *id)
323{
324 int ret;
325 struct mcp2200 *mcp;
326
327 mcp = devm_kzalloc(dev: &hdev->dev, size: sizeof(*mcp), GFP_KERNEL);
328 if (!mcp)
329 return -ENOMEM;
330
331 ret = hid_parse(hdev);
332 if (ret) {
333 hid_err(hdev, "can't parse reports\n");
334 return ret;
335 }
336
337 ret = hid_hw_start(hdev, connect_mask: 0);
338 if (ret) {
339 hid_err(hdev, "can't start hardware\n");
340 return ret;
341 }
342
343 hid_info(hdev, "USB HID v%x.%02x Device [%s] on %s\n", hdev->version >> 8,
344 hdev->version & 0xff, hdev->name, hdev->phys);
345
346 ret = hid_hw_open(hdev);
347 if (ret) {
348 hid_err(hdev, "can't open device\n");
349 hid_hw_stop(hdev);
350 return ret;
351 }
352
353 mutex_init(&mcp->lock);
354 init_completion(x: &mcp->wait_in_report);
355 hid_set_drvdata(hdev, data: mcp);
356 mcp->hdev = hdev;
357
358 mcp->gc = template_chip;
359 mcp->gc.parent = &hdev->dev;
360
361 ret = devm_gpiochip_add_data(&hdev->dev, &mcp->gc, mcp);
362 if (ret < 0) {
363 hid_err(hdev, "Unable to register gpiochip\n");
364 hid_hw_close(hdev);
365 hid_hw_stop(hdev);
366 return ret;
367 }
368
369 return 0;
370}
371
372static void mcp2200_remove(struct hid_device *hdev)
373{
374 hid_hw_close(hdev);
375 hid_hw_stop(hdev);
376}
377
378static const struct hid_device_id mcp2200_devices[] = {
379 { HID_USB_DEVICE(USB_VENDOR_ID_MICROCHIP, USB_DEVICE_ID_MCP2200) },
380 { }
381};
382MODULE_DEVICE_TABLE(hid, mcp2200_devices);
383
384static struct hid_driver mcp2200_driver = {
385 .name = "mcp2200",
386 .id_table = mcp2200_devices,
387 .probe = mcp2200_probe,
388 .remove = mcp2200_remove,
389 .raw_event = mcp2200_raw_event,
390};
391
392/* Register with HID core */
393module_hid_driver(mcp2200_driver);
394
395MODULE_AUTHOR("Johannes Roith <johannes@gnu-linux.rocks>");
396MODULE_DESCRIPTION("MCP2200 Microchip HID USB to GPIO bridge");
397MODULE_LICENSE("GPL");
398

source code of linux/drivers/hid/hid-mcp2200.c