blob: bf6e08e8013e30ad0e78f1d532954a4c13388f8d [file] [log] [blame]
Simon Glassa17d94f2013-02-25 14:08:39 -08001/*
2 * ChromeOS EC multi-function device (SPI)
3 *
4 * Copyright (C) 2012 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
16#include <linux/delay.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/mfd/cros_ec.h>
20#include <linux/mfd/cros_ec_commands.h>
Rhyland Klein01e73c82013-12-09 12:36:09 +010021#include <linux/of.h>
Simon Glassa17d94f2013-02-25 14:08:39 -080022#include <linux/platform_device.h>
23#include <linux/slab.h>
24#include <linux/spi/spi.h>
25
26
27/* The header byte, which follows the preamble */
28#define EC_MSG_HEADER 0xec
29
30/*
31 * Number of EC preamble bytes we read at a time. Since it takes
32 * about 400-500us for the EC to respond there is not a lot of
33 * point in tuning this. If the EC could respond faster then
34 * we could increase this so that might expect the preamble and
35 * message to occur in a single transaction. However, the maximum
36 * SPI transfer size is 256 bytes, so at 5MHz we need a response
37 * time of perhaps <320us (200 bytes / 1600 bits).
38 */
39#define EC_MSG_PREAMBLE_COUNT 32
40
41/*
Doug Anderson9c0b54a2014-04-30 10:44:07 -070042 * Allow for a long time for the EC to respond. We support i2c
43 * tunneling and support fairly long messages for the tunnel (249
44 * bytes long at the moment). If we're talking to a 100 kHz device
45 * on the other end and need to transfer ~256 bytes, then we need:
46 * 10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms
47 *
48 * We'll wait 4 times that to handle clock stretching and other
49 * paranoia.
50 *
51 * It's pretty unlikely that we'll really see a 249 byte tunnel in
52 * anything other than testing. If this was more common we might
53 * consider having slow commands like this require a GET_STATUS
54 * wait loop. The 'flash write' command would be another candidate
55 * for this, clocking in at 2-3ms.
56 */
57#define EC_MSG_DEADLINE_MS 100
Simon Glassa17d94f2013-02-25 14:08:39 -080058
59/*
60 * Time between raising the SPI chip select (for the end of a
61 * transaction) and dropping it again (for the next transaction).
Derek Basehore49f91ac2013-11-18 11:30:48 +010062 * If we go too fast, the EC will miss the transaction. We know that we
63 * need at least 70 us with the 16 MHz STM32 EC, so go with 200 us to be
64 * safe.
Simon Glassa17d94f2013-02-25 14:08:39 -080065 */
Derek Basehore49f91ac2013-11-18 11:30:48 +010066#define EC_SPI_RECOVERY_TIME_NS (200 * 1000)
Simon Glassa17d94f2013-02-25 14:08:39 -080067
Doug Anderson659e1422014-09-18 17:18:54 +020068/*
69 * The EC is unresponsive for a time after a reboot command. Add a
70 * simple delay to make sure that the bus stays locked.
71 */
72#define EC_REBOOT_DELAY_MS 50
73
Simon Glassa17d94f2013-02-25 14:08:39 -080074/**
75 * struct cros_ec_spi - information about a SPI-connected EC
76 *
77 * @spi: SPI device we are connected to
78 * @last_transfer_ns: time that we last finished a transfer, or 0 if there
79 * if no record
Rhyland Klein01e73c82013-12-09 12:36:09 +010080 * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that
81 * is sent when we want to turn off CS at the end of a transaction.
Simon Glassa17d94f2013-02-25 14:08:39 -080082 */
83struct cros_ec_spi {
84 struct spi_device *spi;
85 s64 last_transfer_ns;
Rhyland Klein01e73c82013-12-09 12:36:09 +010086 unsigned int end_of_msg_delay;
Simon Glassa17d94f2013-02-25 14:08:39 -080087};
88
89static void debug_packet(struct device *dev, const char *name, u8 *ptr,
90 int len)
91{
92#ifdef DEBUG
93 int i;
94
95 dev_dbg(dev, "%s: ", name);
96 for (i = 0; i < len; i++)
Thierry Reding9e146f42013-11-18 11:30:49 +010097 pr_cont(" %02x", ptr[i]);
98
99 pr_cont("\n");
Simon Glassa17d94f2013-02-25 14:08:39 -0800100#endif
101}
102
103/**
104 * cros_ec_spi_receive_response - Receive a response from the EC.
105 *
106 * This function has two phases: reading the preamble bytes (since if we read
107 * data from the EC before it is ready to send, we just get preamble) and
108 * reading the actual message.
109 *
110 * The received data is placed into ec_dev->din.
111 *
112 * @ec_dev: ChromeOS EC device
113 * @need_len: Number of message bytes we need to read
114 */
115static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
116 int need_len)
117{
118 struct cros_ec_spi *ec_spi = ec_dev->priv;
119 struct spi_transfer trans;
120 struct spi_message msg;
121 u8 *ptr, *end;
122 int ret;
123 unsigned long deadline;
124 int todo;
125
126 /* Receive data until we see the header byte */
127 deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
Doug Andersonc9a81d62014-04-30 10:44:06 -0700128 while (true) {
129 unsigned long start_jiffies = jiffies;
130
Thierry Redingdaf93d22013-12-09 12:36:10 +0100131 memset(&trans, 0, sizeof(trans));
Simon Glassa17d94f2013-02-25 14:08:39 -0800132 trans.cs_change = 1;
133 trans.rx_buf = ptr = ec_dev->din;
134 trans.len = EC_MSG_PREAMBLE_COUNT;
135
136 spi_message_init(&msg);
137 spi_message_add_tail(&trans, &msg);
138 ret = spi_sync(ec_spi->spi, &msg);
139 if (ret < 0) {
140 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
141 return ret;
142 }
143
144 for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
145 if (*ptr == EC_MSG_HEADER) {
Geert Uytterhoevenc34924b2013-05-08 23:37:45 +0200146 dev_dbg(ec_dev->dev, "msg found at %zd\n",
Simon Glassa17d94f2013-02-25 14:08:39 -0800147 ptr - ec_dev->din);
148 break;
149 }
150 }
Doug Andersonc9a81d62014-04-30 10:44:06 -0700151 if (ptr != end)
152 break;
Simon Glassa17d94f2013-02-25 14:08:39 -0800153
Doug Andersonc9a81d62014-04-30 10:44:06 -0700154 /*
155 * Use the time at the start of the loop as a timeout. This
156 * gives us one last shot at getting the transfer and is useful
157 * in case we got context switched out for a while.
158 */
159 if (time_after(start_jiffies, deadline)) {
Simon Glassa17d94f2013-02-25 14:08:39 -0800160 dev_warn(ec_dev->dev, "EC failed to respond in time\n");
161 return -ETIMEDOUT;
162 }
Doug Andersonc9a81d62014-04-30 10:44:06 -0700163 }
Simon Glassa17d94f2013-02-25 14:08:39 -0800164
165 /*
166 * ptr now points to the header byte. Copy any valid data to the
167 * start of our buffer
168 */
169 todo = end - ++ptr;
170 BUG_ON(todo < 0 || todo > ec_dev->din_size);
171 todo = min(todo, need_len);
172 memmove(ec_dev->din, ptr, todo);
173 ptr = ec_dev->din + todo;
174 dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n",
175 need_len, todo);
176 need_len -= todo;
177
178 /* Receive data until we have it all */
179 while (need_len > 0) {
180 /*
181 * We can't support transfers larger than the SPI FIFO size
182 * unless we have DMA. We don't have DMA on the ISP SPI ports
183 * for Exynos. We need a way of asking SPI driver for
184 * maximum-supported transfer size.
185 */
186 todo = min(need_len, 256);
Geert Uytterhoevenc34924b2013-05-08 23:37:45 +0200187 dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n",
Simon Glassa17d94f2013-02-25 14:08:39 -0800188 todo, need_len, ptr - ec_dev->din);
189
Thierry Redingdaf93d22013-12-09 12:36:10 +0100190 memset(&trans, 0, sizeof(trans));
Simon Glassa17d94f2013-02-25 14:08:39 -0800191 trans.cs_change = 1;
192 trans.rx_buf = ptr;
193 trans.len = todo;
194 spi_message_init(&msg);
195 spi_message_add_tail(&trans, &msg);
196
197 /* send command to EC and read answer */
198 BUG_ON((u8 *)trans.rx_buf - ec_dev->din + todo >
199 ec_dev->din_size);
200 ret = spi_sync(ec_spi->spi, &msg);
201 if (ret < 0) {
202 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
203 return ret;
204 }
205
206 debug_packet(ec_dev->dev, "interim", ptr, todo);
207 ptr += todo;
208 need_len -= todo;
209 }
210
Geert Uytterhoevenc34924b2013-05-08 23:37:45 +0200211 dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din);
Simon Glassa17d94f2013-02-25 14:08:39 -0800212
213 return 0;
214}
215
216/**
Bill Richardson7e6cb5b2014-06-18 11:14:00 -0700217 * cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
Simon Glassa17d94f2013-02-25 14:08:39 -0800218 *
219 * @ec_dev: ChromeOS EC device
220 * @ec_msg: Message to transfer
221 */
Bill Richardson7e6cb5b2014-06-18 11:14:00 -0700222static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
Bill Richardson5d4773e2014-06-18 11:14:02 -0700223 struct cros_ec_command *ec_msg)
Simon Glassa17d94f2013-02-25 14:08:39 -0800224{
225 struct cros_ec_spi *ec_spi = ec_dev->priv;
226 struct spi_transfer trans;
227 struct spi_message msg;
228 int i, len;
229 u8 *ptr;
230 int sum;
231 int ret = 0, final_ret;
Simon Glassa17d94f2013-02-25 14:08:39 -0800232
233 len = cros_ec_prepare_tx(ec_dev, ec_msg);
234 dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
235
236 /* If it's too soon to do another transaction, wait */
237 if (ec_spi->last_transfer_ns) {
Simon Glassa17d94f2013-02-25 14:08:39 -0800238 unsigned long delay; /* The delay completed so far */
239
Thomas Gleixner154adc12014-07-16 21:04:41 +0000240 delay = ktime_get_ns() - ec_spi->last_transfer_ns;
Simon Glassa17d94f2013-02-25 14:08:39 -0800241 if (delay < EC_SPI_RECOVERY_TIME_NS)
David Hendricks1fe36862014-04-30 10:44:04 -0700242 ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
Simon Glassa17d94f2013-02-25 14:08:39 -0800243 }
244
245 /* Transmit phase - send our message */
246 debug_packet(ec_dev->dev, "out", ec_dev->dout, len);
Thierry Redingdaf93d22013-12-09 12:36:10 +0100247 memset(&trans, 0, sizeof(trans));
Simon Glassa17d94f2013-02-25 14:08:39 -0800248 trans.tx_buf = ec_dev->dout;
249 trans.len = len;
250 trans.cs_change = 1;
251 spi_message_init(&msg);
252 spi_message_add_tail(&trans, &msg);
253 ret = spi_sync(ec_spi->spi, &msg);
254
255 /* Get the response */
256 if (!ret) {
257 ret = cros_ec_spi_receive_response(ec_dev,
Bill Richardson5d4773e2014-06-18 11:14:02 -0700258 ec_msg->insize + EC_MSG_TX_PROTO_BYTES);
Simon Glassa17d94f2013-02-25 14:08:39 -0800259 } else {
260 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
261 }
262
Doug Anderson96758052014-06-13 11:13:32 -0700263 /*
264 * Turn off CS, possibly adding a delay to ensure the rising edge
265 * doesn't come too soon after the end of the data.
266 */
Simon Glassa17d94f2013-02-25 14:08:39 -0800267 spi_message_init(&msg);
Doug Anderson96758052014-06-13 11:13:32 -0700268 memset(&trans, 0, sizeof(trans));
269 trans.delay_usecs = ec_spi->end_of_msg_delay;
270 spi_message_add_tail(&trans, &msg);
Rhyland Klein01e73c82013-12-09 12:36:09 +0100271
Simon Glassa17d94f2013-02-25 14:08:39 -0800272 final_ret = spi_sync(ec_spi->spi, &msg);
Thomas Gleixner154adc12014-07-16 21:04:41 +0000273 ec_spi->last_transfer_ns = ktime_get_ns();
Simon Glassa17d94f2013-02-25 14:08:39 -0800274 if (!ret)
275 ret = final_ret;
276 if (ret < 0) {
277 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
Doug Anderson362196e2014-04-30 10:44:05 -0700278 goto exit;
Simon Glassa17d94f2013-02-25 14:08:39 -0800279 }
280
Simon Glassa17d94f2013-02-25 14:08:39 -0800281 ptr = ec_dev->din;
Bill Richardson6db07b62014-06-18 11:14:05 -0700282
283 /* check response error code */
284 ec_msg->result = ptr[0];
285 ret = cros_ec_check_result(ec_dev, ec_msg);
286 if (ret)
Doug Anderson362196e2014-04-30 10:44:05 -0700287 goto exit;
Bill Richardson6db07b62014-06-18 11:14:05 -0700288
Simon Glassa17d94f2013-02-25 14:08:39 -0800289 len = ptr[1];
290 sum = ptr[0] + ptr[1];
Bill Richardson5d4773e2014-06-18 11:14:02 -0700291 if (len > ec_msg->insize) {
Simon Glassa17d94f2013-02-25 14:08:39 -0800292 dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
Bill Richardson5d4773e2014-06-18 11:14:02 -0700293 len, ec_msg->insize);
Doug Anderson362196e2014-04-30 10:44:05 -0700294 ret = -ENOSPC;
295 goto exit;
Simon Glassa17d94f2013-02-25 14:08:39 -0800296 }
297
298 /* copy response packet payload and compute checksum */
299 for (i = 0; i < len; i++) {
300 sum += ptr[i + 2];
Bill Richardson5d4773e2014-06-18 11:14:02 -0700301 if (ec_msg->insize)
302 ec_msg->indata[i] = ptr[i + 2];
Simon Glassa17d94f2013-02-25 14:08:39 -0800303 }
304 sum &= 0xff;
305
306 debug_packet(ec_dev->dev, "in", ptr, len + 3);
307
308 if (sum != ptr[len + 2]) {
309 dev_err(ec_dev->dev,
310 "bad packet checksum, expected %02x, got %02x\n",
311 sum, ptr[len + 2]);
Doug Anderson362196e2014-04-30 10:44:05 -0700312 ret = -EBADMSG;
313 goto exit;
Simon Glassa17d94f2013-02-25 14:08:39 -0800314 }
315
Bill Richardson12ebc8a2014-06-18 11:14:06 -0700316 ret = len;
Doug Anderson362196e2014-04-30 10:44:05 -0700317exit:
Doug Anderson659e1422014-09-18 17:18:54 +0200318 if (ec_msg->command == EC_CMD_REBOOT_EC)
319 msleep(EC_REBOOT_DELAY_MS);
320
Doug Anderson362196e2014-04-30 10:44:05 -0700321 return ret;
Simon Glassa17d94f2013-02-25 14:08:39 -0800322}
323
Rhyland Klein01e73c82013-12-09 12:36:09 +0100324static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
325{
326 struct device_node *np = dev->of_node;
327 u32 val;
328 int ret;
329
330 ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val);
331 if (!ret)
332 ec_spi->end_of_msg_delay = val;
333}
334
Thierry Reding9922b412013-11-25 13:22:30 +0100335static int cros_ec_spi_probe(struct spi_device *spi)
Simon Glassa17d94f2013-02-25 14:08:39 -0800336{
337 struct device *dev = &spi->dev;
338 struct cros_ec_device *ec_dev;
339 struct cros_ec_spi *ec_spi;
340 int err;
341
342 spi->bits_per_word = 8;
343 spi->mode = SPI_MODE_0;
344 err = spi_setup(spi);
345 if (err < 0)
346 return err;
347
348 ec_spi = devm_kzalloc(dev, sizeof(*ec_spi), GFP_KERNEL);
349 if (ec_spi == NULL)
350 return -ENOMEM;
351 ec_spi->spi = spi;
352 ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
353 if (!ec_dev)
354 return -ENOMEM;
355
Rhyland Klein01e73c82013-12-09 12:36:09 +0100356 /* Check for any DT properties */
357 cros_ec_spi_dt_probe(ec_spi, dev);
358
Simon Glassa17d94f2013-02-25 14:08:39 -0800359 spi_set_drvdata(spi, ec_dev);
Simon Glassa17d94f2013-02-25 14:08:39 -0800360 ec_dev->dev = dev;
361 ec_dev->priv = ec_spi;
362 ec_dev->irq = spi->irq;
Bill Richardson7e6cb5b2014-06-18 11:14:00 -0700363 ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
Simon Glassa17d94f2013-02-25 14:08:39 -0800364 ec_dev->ec_name = ec_spi->spi->modalias;
365 ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
366 ec_dev->parent = &ec_spi->spi->dev;
367 ec_dev->din_size = EC_MSG_BYTES + EC_MSG_PREAMBLE_COUNT;
368 ec_dev->dout_size = EC_MSG_BYTES;
369
370 err = cros_ec_register(ec_dev);
371 if (err) {
372 dev_err(dev, "cannot register EC\n");
373 return err;
374 }
375
Prathyush Kfb504972014-06-16 14:12:23 -0700376 device_init_wakeup(&spi->dev, true);
377
Simon Glassa17d94f2013-02-25 14:08:39 -0800378 return 0;
379}
380
Thierry Reding9922b412013-11-25 13:22:30 +0100381static int cros_ec_spi_remove(struct spi_device *spi)
Simon Glassa17d94f2013-02-25 14:08:39 -0800382{
383 struct cros_ec_device *ec_dev;
384
385 ec_dev = spi_get_drvdata(spi);
386 cros_ec_remove(ec_dev);
387
388 return 0;
389}
390
391#ifdef CONFIG_PM_SLEEP
392static int cros_ec_spi_suspend(struct device *dev)
393{
394 struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
395
396 return cros_ec_suspend(ec_dev);
397}
398
399static int cros_ec_spi_resume(struct device *dev)
400{
401 struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
402
403 return cros_ec_resume(ec_dev);
404}
405#endif
406
407static SIMPLE_DEV_PM_OPS(cros_ec_spi_pm_ops, cros_ec_spi_suspend,
408 cros_ec_spi_resume);
409
410static const struct spi_device_id cros_ec_spi_id[] = {
411 { "cros-ec-spi", 0 },
412 { }
413};
414MODULE_DEVICE_TABLE(spi, cros_ec_spi_id);
415
416static struct spi_driver cros_ec_driver_spi = {
417 .driver = {
418 .name = "cros-ec-spi",
419 .owner = THIS_MODULE,
420 .pm = &cros_ec_spi_pm_ops,
421 },
Thierry Reding9922b412013-11-25 13:22:30 +0100422 .probe = cros_ec_spi_probe,
423 .remove = cros_ec_spi_remove,
Simon Glassa17d94f2013-02-25 14:08:39 -0800424 .id_table = cros_ec_spi_id,
425};
426
427module_spi_driver(cros_ec_driver_spi);
428
Thierry Redingea0f8b02013-12-09 11:05:38 +0100429MODULE_LICENSE("GPL v2");
Simon Glassa17d94f2013-02-25 14:08:39 -0800430MODULE_DESCRIPTION("ChromeOS EC multi function device (SPI)");