1 /*
2 * Copyright (C) 2024 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #define LOG_TAG "libpixelusb-i2chelper"
18
19 #include "include/pixelusb/I2cHelper.h"
20
21 #include <dirent.h>
22 #include <utils/Log.h>
23
24 namespace android {
25 namespace hardware {
26 namespace google {
27 namespace pixel {
28 namespace usb {
29
30 // getI2cBusNumberString: Return the I2C bus number as the string type
31 //
32 // The bus number can be extracted from the sub-directory under the hsi2c sysfs
33 // device directory (e.g. /sys/devices/platform/10d60000.hsi2c/) and the pattern
34 // of the sub-directory is /^i2c-\d+$/ where \d+ is the bus number.
getI2cBusNumberString(const string hsi2cPath)35 static string getI2cBusNumberString(const string hsi2cPath) {
36 DIR *dp = opendir(hsi2cPath.c_str());
37
38 if (dp != NULL) {
39 struct dirent *ep;
40
41 while ((ep = readdir(dp))) {
42 if (ep->d_type == DT_DIR) {
43 // Supposed that there is only one sub dir in the pattern "i2c-"
44 if (string::npos != string(ep->d_name).find("i2c-")) {
45 std::strtok(ep->d_name, "-");
46 string busNumber = std::strtok(NULL, "-");
47 closedir(dp);
48 return busNumber;
49 }
50 }
51 }
52 closedir(dp);
53 ALOGE("Failed to find the i2c sub dir under %s", hsi2cPath.c_str());
54 return string("");
55 }
56
57 ALOGE("Failed to open %s", hsi2cPath.c_str());
58 return string("");
59 }
60
61 // getI2cClientPath: Return the full path of the I2C client directory
62 //
63 // There are two forms of the directory path: in client ID and in I2C device name
64 // For example:
65 // client ID: /sys/devices/platform/10d60000.hsi2c/i2c-7/7-0025/
66 // device name: /sys/devices/platform/10d60000.hsi2c/i2c-7/i2c-max77759tcpc/
67 //
68 // The bus number and the client directory name differs across kernel versions and
69 // build targets. Search the bus number first to locate the first level of the sub
70 // directory, and then search the I2C device name under it.
71 //
72 // Append the I2c device name to the full path if found, otherwise, append "bus
73 // number" + "-" + client ID. Note that the client ID must be a 4-digit number
74 // with 0 stuffed in the type of string.
getI2cClientPath(const string hsi2cPath,const string devName,const string clientId)75 string getI2cClientPath(const string hsi2cPath, const string devName, const string clientId) {
76 DIR *dp;
77 string strBusNumber, i2cPathPartial, i2cClientPath;
78
79 strBusNumber = getI2cBusNumberString(hsi2cPath);
80 if (strBusNumber.empty()) {
81 return string("");
82 }
83
84 i2cPathPartial = hsi2cPath + "/i2c-" + strBusNumber;
85 dp = opendir(i2cPathPartial.c_str());
86 if (dp != NULL) {
87 struct dirent *ep;
88 string i2cClientDevice = strBusNumber + "-" + clientId;
89
90 while ((ep = readdir(dp))) {
91 if (ep->d_type == DT_DIR) {
92 if (string::npos != string(ep->d_name).find(devName)) {
93 closedir(dp);
94 return string(i2cPathPartial + "/" + devName + "/");
95 }
96 if (string::npos != string(ep->d_name).find(i2cClientDevice)) {
97 closedir(dp);
98 return string(i2cPathPartial + "/" + i2cClientDevice + "/");
99 }
100 }
101 }
102 closedir(dp);
103 }
104
105 ALOGE("Failed to open %s", i2cPathPartial.c_str());
106 return string("");
107 }
108
109 } // namespace usb
110 } // namespace pixel
111 } // namespace google
112 } // namespace hardware
113 } // namespace android
114