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1/*
2 * cros_ec_lpc - LPC access to the Chrome OS Embedded Controller
3 *
4 * Copyright (C) 2012-2015 Google, Inc
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * This driver uses the Chrome OS EC byte-level message-based protocol for
16 * communicating the keyboard state (which keys are pressed) from a keyboard EC
17 * to the AP over some bus (such as i2c, lpc, spi). The EC does debouncing,
18 * but everything else (including deghosting) is done here. The main
19 * motivation for this is to keep the EC firmware as simple as possible, since
20 * it cannot be easily upgraded and EC flash/IRAM space is relatively
21 * expensive.
22 */
23
24#include <linux/dmi.h>
25#include <linux/delay.h>
26#include <linux/io.h>
27#include <linux/mfd/cros_ec.h>
28#include <linux/mfd/cros_ec_commands.h>
29#include <linux/module.h>
30#include <linux/platform_device.h>
31#include <linux/printk.h>
32
33#define DRV_NAME "cros_ec_lpc"
34
35static int ec_response_timed_out(void)
36{
37 unsigned long one_second = jiffies + HZ;
38
39 usleep_range(200, 300);
40 do {
41 if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK))
42 return 0;
43 usleep_range(100, 200);
44 } while (time_before(jiffies, one_second));
45
46 return 1;
47}
48
49static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
50 struct cros_ec_command *msg)
51{
52 struct ec_host_request *request;
53 struct ec_host_response response;
54 u8 sum = 0;
55 int i;
56 int ret = 0;
57 u8 *dout;
58
59 ret = cros_ec_prepare_tx(ec, msg);
60
61 /* Write buffer */
62 for (i = 0; i < ret; i++)
63 outb(ec->dout[i], EC_LPC_ADDR_HOST_PACKET + i);
64
65 request = (struct ec_host_request *)ec->dout;
66
67 /* Here we go */
68 outb(EC_COMMAND_PROTOCOL_3, EC_LPC_ADDR_HOST_CMD);
69
70 if (ec_response_timed_out()) {
71 dev_warn(ec->dev, "EC responsed timed out\n");
72 ret = -EIO;
73 goto done;
74 }
75
76 /* Check result */
77 msg->result = inb(EC_LPC_ADDR_HOST_DATA);
78 ret = cros_ec_check_result(ec, msg);
79 if (ret)
80 goto done;
81
82 /* Read back response */
83 dout = (u8 *)&response;
84 for (i = 0; i < sizeof(response); i++) {
85 dout[i] = inb(EC_LPC_ADDR_HOST_PACKET + i);
86 sum += dout[i];
87 }
88
89 msg->result = response.result;
90
91 if (response.data_len > msg->insize) {
92 dev_err(ec->dev,
93 "packet too long (%d bytes, expected %d)",
94 response.data_len, msg->insize);
95 ret = -EMSGSIZE;
96 goto done;
97 }
98
99 /* Read response and process checksum */
100 for (i = 0; i < response.data_len; i++) {
101 msg->data[i] =
102 inb(EC_LPC_ADDR_HOST_PACKET + sizeof(response) + i);
103 sum += msg->data[i];
104 }
105
106 if (sum) {
107 dev_err(ec->dev,
108 "bad packet checksum %02x\n",
109 response.checksum);
110 ret = -EBADMSG;
111 goto done;
112 }
113
114 /* Return actual amount of data received */
115 ret = response.data_len;
116done:
117 return ret;
118}
119
120static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
121 struct cros_ec_command *msg)
122{
123 struct ec_lpc_host_args args;
124 int csum;
125 int i;
126 int ret = 0;
127
128 if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
129 msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
130 dev_err(ec->dev,
131 "invalid buffer sizes (out %d, in %d)\n",
132 msg->outsize, msg->insize);
133 return -EINVAL;
134 }
135
136 /* Now actually send the command to the EC and get the result */
137 args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
138 args.command_version = msg->version;
139 args.data_size = msg->outsize;
140
141 /* Initialize checksum */
142 csum = msg->command + args.flags +
143 args.command_version + args.data_size;
144
145 /* Copy data and update checksum */
146 for (i = 0; i < msg->outsize; i++) {
147 outb(msg->data[i], EC_LPC_ADDR_HOST_PARAM + i);
148 csum += msg->data[i];
149 }
150
151 /* Finalize checksum and write args */
152 args.checksum = csum & 0xFF;
153 outb(args.flags, EC_LPC_ADDR_HOST_ARGS);
154 outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1);
155 outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2);
156 outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3);
157
158 /* Here we go */
159 outb(msg->command, EC_LPC_ADDR_HOST_CMD);
160
161 if (ec_response_timed_out()) {
162 dev_warn(ec->dev, "EC responsed timed out\n");
163 ret = -EIO;
164 goto done;
165 }
166
167 /* Check result */
168 msg->result = inb(EC_LPC_ADDR_HOST_DATA);
169 ret = cros_ec_check_result(ec, msg);
170 if (ret)
171 goto done;
172
173 /* Read back args */
174 args.flags = inb(EC_LPC_ADDR_HOST_ARGS);
175 args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1);
176 args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2);
177 args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3);
178
179 if (args.data_size > msg->insize) {
180 dev_err(ec->dev,
181 "packet too long (%d bytes, expected %d)",
182 args.data_size, msg->insize);
183 ret = -ENOSPC;
184 goto done;
185 }
186
187 /* Start calculating response checksum */
188 csum = msg->command + args.flags +
189 args.command_version + args.data_size;
190
191 /* Read response and update checksum */
192 for (i = 0; i < args.data_size; i++) {
193 msg->data[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
194 csum += msg->data[i];
195 }
196
197 /* Verify checksum */
198 if (args.checksum != (csum & 0xFF)) {
199 dev_err(ec->dev,
200 "bad packet checksum, expected %02x, got %02x\n",
201 args.checksum, csum & 0xFF);
202 ret = -EBADMSG;
203 goto done;
204 }
205
206 /* Return actual amount of data received */
207 ret = args.data_size;
208done:
209 return ret;
210}
211
212/* Returns num bytes read, or negative on error. Doesn't need locking. */
213static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
214 unsigned int bytes, void *dest)
215{
216 int i = offset;
217 char *s = dest;
218 int cnt = 0;
219
220 if (offset >= EC_MEMMAP_SIZE - bytes)
221 return -EINVAL;
222
223 /* fixed length */
224 if (bytes) {
225 for (; cnt < bytes; i++, s++, cnt++)
226 *s = inb(EC_LPC_ADDR_MEMMAP + i);
227 return cnt;
228 }
229
230 /* string */
231 for (; i < EC_MEMMAP_SIZE; i++, s++) {
232 *s = inb(EC_LPC_ADDR_MEMMAP + i);
233 cnt++;
234 if (!*s)
235 break;
236 }
237
238 return cnt;
239}
240
241static int cros_ec_lpc_probe(struct platform_device *pdev)
242{
243 struct device *dev = &pdev->dev;
244 struct cros_ec_device *ec_dev;
245 int ret;
246
247 if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
248 dev_name(dev))) {
249 dev_err(dev, "couldn't reserve memmap region\n");
250 return -EBUSY;
251 }
252
253 if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
254 (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
255 dev_err(dev, "EC ID not detected\n");
256 return -ENODEV;
257 }
258
259 if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
260 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
261 dev_err(dev, "couldn't reserve region0\n");
262 return -EBUSY;
263 }
264 if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
265 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
266 dev_err(dev, "couldn't reserve region1\n");
267 return -EBUSY;
268 }
269
270 ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
271 if (!ec_dev)
272 return -ENOMEM;
273
274 platform_set_drvdata(pdev, ec_dev);
275 ec_dev->dev = dev;
276 ec_dev->phys_name = dev_name(dev);
277 ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
278 ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
279 ec_dev->cmd_readmem = cros_ec_lpc_readmem;
280 ec_dev->din_size = sizeof(struct ec_host_response) +
281 sizeof(struct ec_response_get_protocol_info);
282 ec_dev->dout_size = sizeof(struct ec_host_request);
283
284 ret = cros_ec_register(ec_dev);
285 if (ret) {
286 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
287 return ret;
288 }
289
290 return 0;
291}
292
293static int cros_ec_lpc_remove(struct platform_device *pdev)
294{
295 struct cros_ec_device *ec_dev;
296
297 ec_dev = platform_get_drvdata(pdev);
298 cros_ec_remove(ec_dev);
299
300 return 0;
301}
302
303static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = {
304 {
305 /*
306 * Today all Chromebooks/boxes ship with Google_* as version and
307 * coreboot as bios vendor. No other systems with this
308 * combination are known to date.
309 */
310 .matches = {
311 DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
312 DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
313 },
314 },
315 {
316 /* x86-link, the Chromebook Pixel. */
317 .matches = {
318 DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
319 DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
320 },
321 },
322 {
323 /* x86-samus, the Chromebook Pixel 2. */
324 .matches = {
325 DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
326 DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
327 },
328 },
329 {
330 /* x86-peppy, the Acer C720 Chromebook. */
331 .matches = {
332 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
333 DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
334 },
335 },
336 { /* sentinel */ }
337};
338MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
339
340static struct platform_driver cros_ec_lpc_driver = {
341 .driver = {
342 .name = DRV_NAME,
343 },
344 .probe = cros_ec_lpc_probe,
345 .remove = cros_ec_lpc_remove,
346};
347
348static struct platform_device cros_ec_lpc_device = {
349 .name = DRV_NAME
350};
351
352static int __init cros_ec_lpc_init(void)
353{
354 int ret;
355
356 if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
357 pr_err(DRV_NAME ": unsupported system.\n");
358 return -ENODEV;
359 }
360
361 /* Register the driver */
362 ret = platform_driver_register(&cros_ec_lpc_driver);
363 if (ret) {
364 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
365 return ret;
366 }
367
368 /* Register the device, and it'll get hooked up automatically */
369 ret = platform_device_register(&cros_ec_lpc_device);
370 if (ret) {
371 pr_err(DRV_NAME ": can't register device: %d\n", ret);
372 platform_driver_unregister(&cros_ec_lpc_driver);
373 return ret;
374 }
375
376 return 0;
377}
378
379static void __exit cros_ec_lpc_exit(void)
380{
381 platform_device_unregister(&cros_ec_lpc_device);
382 platform_driver_unregister(&cros_ec_lpc_driver);
383}
384
385module_init(cros_ec_lpc_init);
386module_exit(cros_ec_lpc_exit);
387
388MODULE_LICENSE("GPL");
389MODULE_DESCRIPTION("ChromeOS EC LPC driver");