platform/chrome/cros_ec_i2c.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 // I2C interface for ChromeOS Embedded Controller
0003 //
0004 // Copyright (C) 2012 Google, Inc
0005
0006 #include <linux/acpi.h>
0007 #include <linux/delay.h>
0008 #include <linux/kernel.h>
0009 #include <linux/module.h>
0010 #include <linux/i2c.h>
0011 #include <linux/interrupt.h>
0012 #include <linux/platform_data/cros_ec_commands.h>
0013 #include <linux/platform_data/cros_ec_proto.h>
0014 #include <linux/platform_device.h>
0015 #include <linux/slab.h>
0016
0017 #include "cros_ec.h"
0018
0019 /*
0020  * Request format for protocol v3
0021  * byte 0   0xda (EC_COMMAND_PROTOCOL_3)
0022  * byte 1-8 struct ec_host_request
0023  * byte 10- response data
0024  */
0025 struct ec_host_request_i2c {
0026     /* Always 0xda to backward compatible with v2 struct */
0027     uint8_t  command_protocol;
0028     struct ec_host_request ec_request;
0029 } __packed;
0030
0031
0032 /*
0033  * Response format for protocol v3
0034  * byte 0   result code
0035  * byte 1   packet_length
0036  * byte 2-9 struct ec_host_response
0037  * byte 10- response data
0038  */
0039 struct ec_host_response_i2c {
0040     uint8_t result;
0041     uint8_t packet_length;
0042     struct ec_host_response ec_response;
0043 } __packed;
0044
0045 static inline struct cros_ec_device *to_ec_dev(struct device *dev)
0046 {
0047     struct i2c_client *client = to_i2c_client(dev);
0048
0049     return i2c_get_clientdata(client);
0050 }
0051
0052 static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
0053                 struct cros_ec_command *msg)
0054 {
0055     struct i2c_client *client = ec_dev->priv;
0056     int ret = -ENOMEM;
0057     int i;
0058     int packet_len;
0059     u8 *out_buf = NULL;
0060     u8 *in_buf = NULL;
0061     u8 sum;
0062     struct i2c_msg i2c_msg[2];
0063     struct ec_host_response *ec_response;
0064     struct ec_host_request_i2c *ec_request_i2c;
0065     struct ec_host_response_i2c *ec_response_i2c;
0066     int request_header_size = sizeof(struct ec_host_request_i2c);
0067     int response_header_size = sizeof(struct ec_host_response_i2c);
0068
0069     i2c_msg[0].addr = client->addr;
0070     i2c_msg[0].flags = 0;
0071     i2c_msg[1].addr = client->addr;
0072     i2c_msg[1].flags = I2C_M_RD;
0073
0074     packet_len = msg->insize + response_header_size;
0075     if (packet_len > ec_dev->din_size) {
0076         ret = -EINVAL;
0077         goto done;
0078     }
0079     in_buf = ec_dev->din;
0080     i2c_msg[1].len = packet_len;
0081     i2c_msg[1].buf = (char *) in_buf;
0082
0083     packet_len = msg->outsize + request_header_size;
0084     if (packet_len > ec_dev->dout_size) {
0085         ret = -EINVAL;
0086         goto done;
0087     }
0088     out_buf = ec_dev->dout;
0089     i2c_msg[0].len = packet_len;
0090     i2c_msg[0].buf = (char *) out_buf;
0091
0092     /* create request data */
0093     ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
0094     ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
0095
0096     ec_dev->dout++;
0097     ret = cros_ec_prepare_tx(ec_dev, msg);
0098     if (ret < 0)
0099         goto done;
0100     ec_dev->dout--;
0101
0102     /* send command to EC and read answer */
0103     ret = i2c_transfer(client->adapter, i2c_msg, 2);
0104     if (ret < 0) {
0105         dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
0106         goto done;
0107     } else if (ret != 2) {
0108         dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
0109         ret = -EIO;
0110         goto done;
0111     }
0112
0113     ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
0114     msg->result = ec_response_i2c->result;
0115     ec_response = &ec_response_i2c->ec_response;
0116
0117     switch (msg->result) {
0118     case EC_RES_SUCCESS:
0119         break;
0120     case EC_RES_IN_PROGRESS:
0121         ret = -EAGAIN;
0122         dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
0123             msg->command);
0124         goto done;
0125
0126     default:
0127         dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
0128             msg->command, msg->result);
0129         /*
0130          * When we send v3 request to v2 ec, ec won't recognize the
0131          * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
0132          * EC_RES_INVALID_COMMAND with zero data length.
0133          *
0134          * In case of invalid command for v3 protocol the data length
0135          * will be at least sizeof(struct ec_host_response)
0136          */
0137         if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
0138             ec_response_i2c->packet_length == 0) {
0139             ret = -EPROTONOSUPPORT;
0140             goto done;
0141         }
0142     }
0143
0144     if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
0145         dev_err(ec_dev->dev,
0146             "response of %u bytes too short; not a full header\n",
0147             ec_response_i2c->packet_length);
0148         ret = -EBADMSG;
0149         goto done;
0150     }
0151
0152     if (msg->insize < ec_response->data_len) {
0153         dev_err(ec_dev->dev,
0154             "response data size is too large: expected %u, got %u\n",
0155             msg->insize,
0156             ec_response->data_len);
0157         ret = -EMSGSIZE;
0158         goto done;
0159     }
0160
0161     /* copy response packet payload and compute checksum */
0162     sum = 0;
0163     for (i = 0; i < sizeof(struct ec_host_response); i++)
0164         sum += ((u8 *)ec_response)[i];
0165
0166     memcpy(msg->data,
0167            in_buf + response_header_size,
0168            ec_response->data_len);
0169     for (i = 0; i < ec_response->data_len; i++)
0170         sum += msg->data[i];
0171
0172     /* All bytes should sum to zero */
0173     if (sum) {
0174         dev_err(ec_dev->dev, "bad packet checksum\n");
0175         ret = -EBADMSG;
0176         goto done;
0177     }
0178
0179     ret = ec_response->data_len;
0180
0181 done:
0182     if (msg->command == EC_CMD_REBOOT_EC)
0183         msleep(EC_REBOOT_DELAY_MS);
0184
0185     return ret;
0186 }
0187
0188 static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
0189                 struct cros_ec_command *msg)
0190 {
0191     struct i2c_client *client = ec_dev->priv;
0192     int ret = -ENOMEM;
0193     int i;
0194     int len;
0195     int packet_len;
0196     u8 *out_buf = NULL;
0197     u8 *in_buf = NULL;
0198     u8 sum;
0199     struct i2c_msg i2c_msg[2];
0200
0201     i2c_msg[0].addr = client->addr;
0202     i2c_msg[0].flags = 0;
0203     i2c_msg[1].addr = client->addr;
0204     i2c_msg[1].flags = I2C_M_RD;
0205
0206     /*
0207      * allocate larger packet (one byte for checksum, one byte for
0208      * length, and one for result code)
0209      */
0210     packet_len = msg->insize + 3;
0211     in_buf = kzalloc(packet_len, GFP_KERNEL);
0212     if (!in_buf)
0213         goto done;
0214     i2c_msg[1].len = packet_len;
0215     i2c_msg[1].buf = (char *)in_buf;
0216
0217     /*
0218      * allocate larger packet (one byte for checksum, one for
0219      * command code, one for length, and one for command version)
0220      */
0221     packet_len = msg->outsize + 4;
0222     out_buf = kzalloc(packet_len, GFP_KERNEL);
0223     if (!out_buf)
0224         goto done;
0225     i2c_msg[0].len = packet_len;
0226     i2c_msg[0].buf = (char *)out_buf;
0227
0228     out_buf[0] = EC_CMD_VERSION0 + msg->version;
0229     out_buf[1] = msg->command;
0230     out_buf[2] = msg->outsize;
0231
0232     /* copy message payload and compute checksum */
0233     sum = out_buf[0] + out_buf[1] + out_buf[2];
0234     for (i = 0; i < msg->outsize; i++) {
0235         out_buf[3 + i] = msg->data[i];
0236         sum += out_buf[3 + i];
0237     }
0238     out_buf[3 + msg->outsize] = sum;
0239
0240     /* send command to EC and read answer */
0241     ret = i2c_transfer(client->adapter, i2c_msg, 2);
0242     if (ret < 0) {
0243         dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
0244         goto done;
0245     } else if (ret != 2) {
0246         dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
0247         ret = -EIO;
0248         goto done;
0249     }
0250
0251     /* check response error code */
0252     msg->result = i2c_msg[1].buf[0];
0253     ret = cros_ec_check_result(ec_dev, msg);
0254     if (ret)
0255         goto done;
0256
0257     len = in_buf[1];
0258     if (len > msg->insize) {
0259         dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
0260             len, msg->insize);
0261         ret = -ENOSPC;
0262         goto done;
0263     }
0264
0265     /* copy response packet payload and compute checksum */
0266     sum = in_buf[0] + in_buf[1];
0267     for (i = 0; i < len; i++) {
0268         msg->data[i] = in_buf[2 + i];
0269         sum += in_buf[2 + i];
0270     }
0271     dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
0272         i2c_msg[1].len, in_buf, sum);
0273     if (sum != in_buf[2 + len]) {
0274         dev_err(ec_dev->dev, "bad packet checksum\n");
0275         ret = -EBADMSG;
0276         goto done;
0277     }
0278
0279     ret = len;
0280 done:
0281     kfree(in_buf);
0282     kfree(out_buf);
0283     if (msg->command == EC_CMD_REBOOT_EC)
0284         msleep(EC_REBOOT_DELAY_MS);
0285
0286     return ret;
0287 }
0288
0289 static int cros_ec_i2c_probe(struct i2c_client *client,
0290                  const struct i2c_device_id *dev_id)
0291 {
0292     struct device *dev = &client->dev;
0293     struct cros_ec_device *ec_dev = NULL;
0294     int err;
0295
0296     ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
0297     if (!ec_dev)
0298         return -ENOMEM;
0299
0300     i2c_set_clientdata(client, ec_dev);
0301     ec_dev->dev = dev;
0302     ec_dev->priv = client;
0303     ec_dev->irq = client->irq;
0304     ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
0305     ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
0306     ec_dev->phys_name = client->adapter->name;
0307     ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
0308                sizeof(struct ec_response_get_protocol_info);
0309     ec_dev->dout_size = sizeof(struct ec_host_request_i2c);
0310
0311     err = cros_ec_register(ec_dev);
0312     if (err) {
0313         dev_err(dev, "cannot register EC\n");
0314         return err;
0315     }
0316
0317     return 0;
0318 }
0319
0320 static int cros_ec_i2c_remove(struct i2c_client *client)
0321 {
0322     struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
0323
0324     cros_ec_unregister(ec_dev);
0325
0326     return 0;
0327 }
0328
0329 #ifdef CONFIG_PM_SLEEP
0330 static int cros_ec_i2c_suspend(struct device *dev)
0331 {
0332     struct cros_ec_device *ec_dev = to_ec_dev(dev);
0333
0334     return cros_ec_suspend(ec_dev);
0335 }
0336
0337 static int cros_ec_i2c_resume(struct device *dev)
0338 {
0339     struct cros_ec_device *ec_dev = to_ec_dev(dev);
0340
0341     return cros_ec_resume(ec_dev);
0342 }
0343 #endif
0344
0345 static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
0346     SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
0347 };
0348
0349 #ifdef CONFIG_OF
0350 static const struct of_device_id cros_ec_i2c_of_match[] = {
0351     { .compatible = "google,cros-ec-i2c", },
0352     { /* sentinel */ },
0353 };
0354 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
0355 #endif
0356
0357 static const struct i2c_device_id cros_ec_i2c_id[] = {
0358     { "cros-ec-i2c", 0 },
0359     { }
0360 };
0361 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
0362
0363 #ifdef CONFIG_ACPI
0364 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
0365     { "GOOG0008", 0 },
0366     { /* sentinel */ }
0367 };
0368 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
0369 #endif
0370
0371 static struct i2c_driver cros_ec_driver = {
0372     .driver = {
0373         .name   = "cros-ec-i2c",
0374         .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
0375         .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
0376         .pm = &cros_ec_i2c_pm_ops,
0377     },
0378     .probe      = cros_ec_i2c_probe,
0379     .remove     = cros_ec_i2c_remove,
0380     .id_table   = cros_ec_i2c_id,
0381 };
0382
0383 module_i2c_driver(cros_ec_driver);
0384
0385 MODULE_LICENSE("GPL v2");
0386 MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");