chrome/wilco_ec/debugfs.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * debugfs attributes for Wilco EC
0004  *
0005  * Copyright 2019 Google LLC
0006  *
0007  * See Documentation/ABI/testing/debugfs-wilco-ec for usage.
0008  */
0009
0010 #include <linux/ctype.h>
0011 #include <linux/debugfs.h>
0012 #include <linux/fs.h>
0013 #include <linux/module.h>
0014 #include <linux/platform_data/wilco-ec.h>
0015 #include <linux/platform_device.h>
0016
0017 #define DRV_NAME "wilco-ec-debugfs"
0018
0019 /* The raw bytes will take up more space when represented as a hex string */
0020 #define FORMATTED_BUFFER_SIZE (EC_MAILBOX_DATA_SIZE * 4)
0021
0022 struct wilco_ec_debugfs {
0023     struct wilco_ec_device *ec;
0024     struct dentry *dir;
0025     size_t response_size;
0026     u8 raw_data[EC_MAILBOX_DATA_SIZE];
0027     u8 formatted_data[FORMATTED_BUFFER_SIZE];
0028 };
0029 static struct wilco_ec_debugfs *debug_info;
0030
0031 /**
0032  * parse_hex_sentence() - Convert a ascii hex representation into byte array.
0033  * @in: Input buffer of ascii.
0034  * @isize: Length of input buffer.
0035  * @out: Output buffer.
0036  * @osize: Length of output buffer, e.g. max number of bytes to parse.
0037  *
0038  * An valid input is a series of ascii hexadecimal numbers, separated by spaces.
0039  * An example valid input is
0040  * "   00 f2 0    000076 6 0  ff"
0041  *
0042  * If an individual "word" within the hex sentence is longer than MAX_WORD_SIZE,
0043  * then the sentence is illegal, and parsing will fail.
0044  *
0045  * Return: Number of bytes parsed, or negative error code on failure.
0046  */
0047 static int parse_hex_sentence(const char *in, int isize, u8 *out, int osize)
0048 {
0049     int n_parsed = 0;
0050     int word_start = 0;
0051     int word_end;
0052     int word_len;
0053     /* Temp buffer for holding a "word" of chars that represents one byte */
0054     #define MAX_WORD_SIZE 16
0055     char tmp[MAX_WORD_SIZE + 1];
0056     u8 byte;
0057
0058     while (word_start < isize && n_parsed < osize) {
0059         /* Find the start of the next word */
0060         while (word_start < isize && isspace(in[word_start]))
0061             word_start++;
0062          /* reached the end of the input before next word? */
0063         if (word_start >= isize)
0064             break;
0065
0066         /* Find the end of this word */
0067         word_end = word_start;
0068         while (word_end < isize && !isspace(in[word_end]))
0069             word_end++;
0070
0071         /* Copy to a tmp NULL terminated string */
0072         word_len = word_end - word_start;
0073         if (word_len > MAX_WORD_SIZE)
0074             return -EINVAL;
0075         memcpy(tmp, in + word_start, word_len);
0076         tmp[word_len] = '\0';
0077
0078         /*
0079          * Convert from hex string, place in output. If fails to parse,
0080          * just return -EINVAL because specific error code is only
0081          * relevant for this one word, returning it would be confusing.
0082          */
0083         if (kstrtou8(tmp, 16, &byte))
0084             return -EINVAL;
0085         out[n_parsed++] = byte;
0086
0087         word_start = word_end;
0088     }
0089     return n_parsed;
0090 }
0091
0092 /* The message type takes up two bytes*/
0093 #define TYPE_AND_DATA_SIZE ((EC_MAILBOX_DATA_SIZE) + 2)
0094
0095 static ssize_t raw_write(struct file *file, const char __user *user_buf,
0096              size_t count, loff_t *ppos)
0097 {
0098     char *buf = debug_info->formatted_data;
0099     struct wilco_ec_message msg;
0100     u8 request_data[TYPE_AND_DATA_SIZE];
0101     ssize_t kcount;
0102     int ret;
0103
0104     if (count > FORMATTED_BUFFER_SIZE)
0105         return -EINVAL;
0106
0107     kcount = simple_write_to_buffer(buf, FORMATTED_BUFFER_SIZE, ppos,
0108                     user_buf, count);
0109     if (kcount < 0)
0110         return kcount;
0111
0112     ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE);
0113     if (ret < 0)
0114         return ret;
0115     /* Need at least two bytes for message type and one byte of data */
0116     if (ret < 3)
0117         return -EINVAL;
0118
0119     msg.type = request_data[0] << 8 | request_data[1];
0120     msg.flags = 0;
0121     msg.request_data = request_data + 2;
0122     msg.request_size = ret - 2;
0123     memset(debug_info->raw_data, 0, sizeof(debug_info->raw_data));
0124     msg.response_data = debug_info->raw_data;
0125     msg.response_size = EC_MAILBOX_DATA_SIZE;
0126
0127     ret = wilco_ec_mailbox(debug_info->ec, &msg);
0128     if (ret < 0)
0129         return ret;
0130     debug_info->response_size = ret;
0131
0132     return count;
0133 }
0134
0135 static ssize_t raw_read(struct file *file, char __user *user_buf, size_t count,
0136             loff_t *ppos)
0137 {
0138     int fmt_len = 0;
0139
0140     if (debug_info->response_size) {
0141         fmt_len = hex_dump_to_buffer(debug_info->raw_data,
0142                          debug_info->response_size,
0143                          16, 1, debug_info->formatted_data,
0144                          sizeof(debug_info->formatted_data),
0145                          true);
0146         /* Only return response the first time it is read */
0147         debug_info->response_size = 0;
0148     }
0149
0150     return simple_read_from_buffer(user_buf, count, ppos,
0151                        debug_info->formatted_data, fmt_len);
0152 }
0153
0154 static const struct file_operations fops_raw = {
0155     .owner = THIS_MODULE,
0156     .read = raw_read,
0157     .write = raw_write,
0158     .llseek = no_llseek,
0159 };
0160
0161 #define CMD_KB_CHROME       0x88
0162 #define SUB_CMD_H1_GPIO     0x0A
0163 #define SUB_CMD_TEST_EVENT  0x0B
0164
0165 struct ec_request {
0166     u8 cmd;     /* Always CMD_KB_CHROME */
0167     u8 reserved;
0168     u8 sub_cmd;
0169 } __packed;
0170
0171 struct ec_response {
0172     u8 status;  /* 0 if allowed */
0173     u8 val;
0174 } __packed;
0175
0176 static int send_ec_cmd(struct wilco_ec_device *ec, u8 sub_cmd, u8 *out_val)
0177 {
0178     struct ec_request rq;
0179     struct ec_response rs;
0180     struct wilco_ec_message msg;
0181     int ret;
0182
0183     memset(&rq, 0, sizeof(rq));
0184     rq.cmd = CMD_KB_CHROME;
0185     rq.sub_cmd = sub_cmd;
0186
0187     memset(&msg, 0, sizeof(msg));
0188     msg.type = WILCO_EC_MSG_LEGACY;
0189     msg.request_data = &rq;
0190     msg.request_size = sizeof(rq);
0191     msg.response_data = &rs;
0192     msg.response_size = sizeof(rs);
0193     ret = wilco_ec_mailbox(ec, &msg);
0194     if (ret < 0)
0195         return ret;
0196     if (rs.status)
0197         return -EIO;
0198
0199     *out_val = rs.val;
0200
0201     return 0;
0202 }
0203
0204 /**
0205  * h1_gpio_get() - Gets h1 gpio status.
0206  * @arg: The wilco EC device.
0207  * @val: BIT(0)=ENTRY_TO_FACT_MODE, BIT(1)=SPI_CHROME_SEL
0208  */
0209 static int h1_gpio_get(void *arg, u64 *val)
0210 {
0211     int ret;
0212
0213     ret = send_ec_cmd(arg, SUB_CMD_H1_GPIO, (u8 *)val);
0214     if (ret == 0)
0215         *val &= 0xFF;
0216     return ret;
0217 }
0218
0219 DEFINE_DEBUGFS_ATTRIBUTE(fops_h1_gpio, h1_gpio_get, NULL, "0x%02llx\n");
0220
0221 /**
0222  * test_event_set() - Sends command to EC to cause an EC test event.
0223  * @arg: The wilco EC device.
0224  * @val: unused.
0225  */
0226 static int test_event_set(void *arg, u64 val)
0227 {
0228     u8 ret;
0229
0230     return send_ec_cmd(arg, SUB_CMD_TEST_EVENT, &ret);
0231 }
0232
0233 /* Format is unused since it is only required for get method which is NULL */
0234 DEFINE_DEBUGFS_ATTRIBUTE(fops_test_event, NULL, test_event_set, "%llu\n");
0235
0236 /**
0237  * wilco_ec_debugfs_probe() - Create the debugfs node
0238  * @pdev: The platform device, probably created in core.c
0239  *
0240  * Try to create a debugfs node. If it fails, then we don't want to change
0241  * behavior at all, this is for debugging after all. Just fail silently.
0242  *
0243  * Return: 0 always.
0244  */
0245 static int wilco_ec_debugfs_probe(struct platform_device *pdev)
0246 {
0247     struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
0248
0249     debug_info = devm_kzalloc(&pdev->dev, sizeof(*debug_info), GFP_KERNEL);
0250     if (!debug_info)
0251         return 0;
0252     debug_info->ec = ec;
0253     debug_info->dir = debugfs_create_dir("wilco_ec", NULL);
0254     if (!debug_info->dir)
0255         return 0;
0256     debugfs_create_file("raw", 0644, debug_info->dir, NULL, &fops_raw);
0257     debugfs_create_file("h1_gpio", 0444, debug_info->dir, ec,
0258                 &fops_h1_gpio);
0259     debugfs_create_file("test_event", 0200, debug_info->dir, ec,
0260                 &fops_test_event);
0261
0262     return 0;
0263 }
0264
0265 static int wilco_ec_debugfs_remove(struct platform_device *pdev)
0266 {
0267     debugfs_remove_recursive(debug_info->dir);
0268
0269     return 0;
0270 }
0271
0272 static struct platform_driver wilco_ec_debugfs_driver = {
0273     .driver = {
0274         .name = DRV_NAME,
0275     },
0276     .probe = wilco_ec_debugfs_probe,
0277     .remove = wilco_ec_debugfs_remove,
0278 };
0279
0280 module_platform_driver(wilco_ec_debugfs_driver);
0281
0282 MODULE_ALIAS("platform:" DRV_NAME);
0283 MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");
0284 MODULE_LICENSE("GPL v2");
0285 MODULE_DESCRIPTION("Wilco EC debugfs driver");