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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/mfd/cros_ec.h> | |
27 | #include <linux/mfd/cros_ec_commands.h> | |
28 | #include <linux/module.h> | |
29 | #include <linux/platform_device.h> | |
30 | #include <linux/printk.h> | |
31 | ||
32 | #define DRV_NAME "cros_ec_lpc" | |
33 | ||
34 | static int ec_response_timed_out(void) | |
35 | { | |
36 | unsigned long one_second = jiffies + HZ; | |
37 | ||
38 | usleep_range(200, 300); | |
39 | do { | |
40 | if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK)) | |
41 | return 0; | |
42 | usleep_range(100, 200); | |
43 | } while (time_before(jiffies, one_second)); | |
44 | ||
45 | return 1; | |
46 | } | |
47 | ||
48 | static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec, | |
49 | struct cros_ec_command *msg) | |
50 | { | |
51 | struct ec_lpc_host_args args; | |
52 | int csum; | |
53 | int i; | |
54 | int ret = 0; | |
55 | ||
56 | if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE || | |
57 | msg->insize > EC_PROTO2_MAX_PARAM_SIZE) { | |
58 | dev_err(ec->dev, | |
59 | "invalid buffer sizes (out %d, in %d)\n", | |
60 | msg->outsize, msg->insize); | |
61 | return -EINVAL; | |
62 | } | |
63 | ||
64 | /* Now actually send the command to the EC and get the result */ | |
65 | args.flags = EC_HOST_ARGS_FLAG_FROM_HOST; | |
66 | args.command_version = msg->version; | |
67 | args.data_size = msg->outsize; | |
68 | ||
69 | /* Initialize checksum */ | |
70 | csum = msg->command + args.flags + | |
71 | args.command_version + args.data_size; | |
72 | ||
73 | /* Copy data and update checksum */ | |
74 | for (i = 0; i < msg->outsize; i++) { | |
75 | outb(msg->outdata[i], EC_LPC_ADDR_HOST_PARAM + i); | |
76 | csum += msg->outdata[i]; | |
77 | } | |
78 | ||
79 | /* Finalize checksum and write args */ | |
80 | args.checksum = csum & 0xFF; | |
81 | outb(args.flags, EC_LPC_ADDR_HOST_ARGS); | |
82 | outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1); | |
83 | outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2); | |
84 | outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3); | |
85 | ||
86 | /* Here we go */ | |
87 | outb(msg->command, EC_LPC_ADDR_HOST_CMD); | |
88 | ||
89 | if (ec_response_timed_out()) { | |
90 | dev_warn(ec->dev, "EC responsed timed out\n"); | |
91 | ret = -EIO; | |
92 | goto done; | |
93 | } | |
94 | ||
95 | /* Check result */ | |
96 | msg->result = inb(EC_LPC_ADDR_HOST_DATA); | |
97 | ||
98 | switch (msg->result) { | |
99 | case EC_RES_SUCCESS: | |
100 | break; | |
101 | case EC_RES_IN_PROGRESS: | |
102 | ret = -EAGAIN; | |
103 | dev_dbg(ec->dev, "command 0x%02x in progress\n", | |
104 | msg->command); | |
105 | goto done; | |
106 | default: | |
107 | dev_dbg(ec->dev, "command 0x%02x returned %d\n", | |
108 | msg->command, msg->result); | |
109 | } | |
110 | ||
111 | /* Read back args */ | |
112 | args.flags = inb(EC_LPC_ADDR_HOST_ARGS); | |
113 | args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1); | |
114 | args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2); | |
115 | args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3); | |
116 | ||
117 | if (args.data_size > msg->insize) { | |
118 | dev_err(ec->dev, | |
119 | "packet too long (%d bytes, expected %d)", | |
120 | args.data_size, msg->insize); | |
121 | ret = -ENOSPC; | |
122 | goto done; | |
123 | } | |
124 | ||
125 | /* Start calculating response checksum */ | |
126 | csum = msg->command + args.flags + | |
127 | args.command_version + args.data_size; | |
128 | ||
129 | /* Read response and update checksum */ | |
130 | for (i = 0; i < args.data_size; i++) { | |
131 | msg->indata[i] = inb(EC_LPC_ADDR_HOST_PARAM + i); | |
132 | csum += msg->indata[i]; | |
133 | } | |
134 | ||
135 | /* Verify checksum */ | |
136 | if (args.checksum != (csum & 0xFF)) { | |
137 | dev_err(ec->dev, | |
138 | "bad packet checksum, expected %02x, got %02x\n", | |
139 | args.checksum, csum & 0xFF); | |
140 | ret = -EBADMSG; | |
141 | goto done; | |
142 | } | |
143 | ||
144 | /* Return actual amount of data received */ | |
145 | ret = args.data_size; | |
146 | done: | |
147 | return ret; | |
148 | } | |
149 | ||
150 | /* Returns num bytes read, or negative on error. Doesn't need locking. */ | |
151 | static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset, | |
152 | unsigned int bytes, void *dest) | |
153 | { | |
154 | int i = offset; | |
155 | char *s = dest; | |
156 | int cnt = 0; | |
157 | ||
158 | if (offset >= EC_MEMMAP_SIZE - bytes) | |
159 | return -EINVAL; | |
160 | ||
161 | /* fixed length */ | |
162 | if (bytes) { | |
163 | for (; cnt < bytes; i++, s++, cnt++) | |
164 | *s = inb(EC_LPC_ADDR_MEMMAP + i); | |
165 | return cnt; | |
166 | } | |
167 | ||
168 | /* string */ | |
169 | for (; i < EC_MEMMAP_SIZE; i++, s++) { | |
170 | *s = inb(EC_LPC_ADDR_MEMMAP + i); | |
171 | cnt++; | |
172 | if (!*s) | |
173 | break; | |
174 | } | |
175 | ||
176 | return cnt; | |
177 | } | |
178 | ||
179 | static int cros_ec_lpc_probe(struct platform_device *pdev) | |
180 | { | |
181 | struct device *dev = &pdev->dev; | |
182 | struct cros_ec_device *ec_dev; | |
183 | int ret; | |
184 | ||
185 | if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE, | |
186 | dev_name(dev))) { | |
187 | dev_err(dev, "couldn't reserve memmap region\n"); | |
188 | return -EBUSY; | |
189 | } | |
190 | ||
191 | if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') || | |
192 | (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) { | |
193 | dev_err(dev, "EC ID not detected\n"); | |
194 | return -ENODEV; | |
195 | } | |
196 | ||
197 | if (!devm_request_region(dev, EC_HOST_CMD_REGION0, | |
198 | EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { | |
199 | dev_err(dev, "couldn't reserve region0\n"); | |
200 | return -EBUSY; | |
201 | } | |
202 | if (!devm_request_region(dev, EC_HOST_CMD_REGION1, | |
203 | EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { | |
204 | dev_err(dev, "couldn't reserve region1\n"); | |
205 | return -EBUSY; | |
206 | } | |
207 | ||
208 | ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL); | |
209 | if (!ec_dev) | |
210 | return -ENOMEM; | |
211 | ||
212 | platform_set_drvdata(pdev, ec_dev); | |
213 | ec_dev->dev = dev; | |
214 | ec_dev->ec_name = pdev->name; | |
215 | ec_dev->phys_name = dev_name(dev); | |
216 | ec_dev->parent = dev; | |
217 | ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc; | |
218 | ec_dev->cmd_readmem = cros_ec_lpc_readmem; | |
219 | ||
220 | ret = cros_ec_register(ec_dev); | |
221 | if (ret) { | |
222 | dev_err(dev, "couldn't register ec_dev (%d)\n", ret); | |
223 | return ret; | |
224 | } | |
225 | ||
226 | return 0; | |
227 | } | |
228 | ||
229 | static int cros_ec_lpc_remove(struct platform_device *pdev) | |
230 | { | |
231 | struct cros_ec_device *ec_dev; | |
232 | ||
233 | ec_dev = platform_get_drvdata(pdev); | |
234 | cros_ec_remove(ec_dev); | |
235 | ||
236 | return 0; | |
237 | } | |
238 | ||
239 | static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = { | |
240 | { | |
241 | /* | |
242 | * Today all Chromebooks/boxes ship with Google_* as version and | |
243 | * coreboot as bios vendor. No other systems with this | |
244 | * combination are known to date. | |
245 | */ | |
246 | .matches = { | |
247 | DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"), | |
248 | DMI_MATCH(DMI_BIOS_VERSION, "Google_"), | |
249 | }, | |
250 | }, | |
251 | { | |
252 | /* x86-link, the Chromebook Pixel. */ | |
253 | .matches = { | |
254 | DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"), | |
255 | DMI_MATCH(DMI_PRODUCT_NAME, "Link"), | |
256 | }, | |
257 | }, | |
258 | { | |
259 | /* x86-peppy, the Acer C720 Chromebook. */ | |
260 | .matches = { | |
261 | DMI_MATCH(DMI_SYS_VENDOR, "Acer"), | |
262 | DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"), | |
263 | }, | |
264 | }, | |
265 | { /* sentinel */ } | |
266 | }; | |
267 | MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table); | |
268 | ||
269 | static struct platform_driver cros_ec_lpc_driver = { | |
270 | .driver = { | |
271 | .name = DRV_NAME, | |
272 | .owner = THIS_MODULE, | |
273 | }, | |
274 | .probe = cros_ec_lpc_probe, | |
275 | .remove = cros_ec_lpc_remove, | |
276 | }; | |
277 | ||
278 | static struct platform_device cros_ec_lpc_device = { | |
279 | .name = DRV_NAME | |
280 | }; | |
281 | ||
282 | static int __init cros_ec_lpc_init(void) | |
283 | { | |
284 | int ret; | |
285 | ||
286 | if (!dmi_check_system(cros_ec_lpc_dmi_table)) { | |
287 | pr_err(DRV_NAME ": unsupported system.\n"); | |
288 | return -ENODEV; | |
289 | } | |
290 | ||
291 | /* Register the driver */ | |
292 | ret = platform_driver_register(&cros_ec_lpc_driver); | |
293 | if (ret) { | |
294 | pr_err(DRV_NAME ": can't register driver: %d\n", ret); | |
295 | return ret; | |
296 | } | |
297 | ||
298 | /* Register the device, and it'll get hooked up automatically */ | |
299 | ret = platform_device_register(&cros_ec_lpc_device); | |
300 | if (ret) { | |
301 | pr_err(DRV_NAME ": can't register device: %d\n", ret); | |
302 | platform_driver_unregister(&cros_ec_lpc_driver); | |
303 | return ret; | |
304 | } | |
305 | ||
306 | return 0; | |
307 | } | |
308 | ||
309 | static void __exit cros_ec_lpc_exit(void) | |
310 | { | |
311 | platform_device_unregister(&cros_ec_lpc_device); | |
312 | platform_driver_unregister(&cros_ec_lpc_driver); | |
313 | } | |
314 | ||
315 | module_init(cros_ec_lpc_init); | |
316 | module_exit(cros_ec_lpc_exit); | |
317 | ||
318 | MODULE_LICENSE("GPL"); | |
319 | MODULE_DESCRIPTION("ChromeOS EC LPC driver"); |