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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "gpio_driver_sysfs.h"
#include <fcntl.h>
#include <string>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <base/logging.h>
namespace android {
namespace {
// Path to sysfd gpio.
const char kSysfsGpioPathPrefix[] = "/sys/class/gpio/gpio";
// Path to export file.
const char kSysfsGpioExportPath[] = "/sys/class/gpio/export";
// Direction filename.
const char kDirection[] = "direction";
// Value filename.
const char kValue[] = "value";
// Active low filename.
const char kActiveLowFile[] = "active_low";
// Edge filename.
const char kEdge[] = "edge";
// Edge values.
const char kEdgeNoneValue[] = "none";
const char kEdgeRisingValue[] = "rising";
const char kEdgeFallingValue[] = "falling";
const char kEdgeBothValue[] = "both";
// Direction values
const char kDirHigh[] = "high";
const char kDirLow[] = "low";
const char kDirIn[] = "in";
// Value values.
const char kValueHigh[] = "1";
const char kValueLow[] = "0";
} // namespace
GpioDriverSysfs::GpioDriverSysfs(void* arg) : fd_(-1) {}
GpioDriverSysfs::~GpioDriverSysfs() {
if (fd_ >= 0) {
close(fd_);
}
}
bool GpioDriverSysfs::Init(uint32_t index) {
if (!ExportGpio(index)) {
LOG(WARNING) << "GpioDriverSysfs: Failed to export " << index;
return false;
}
std::string path = kSysfsGpioPathPrefix + std::to_string(index);
int fd = open(path.c_str(), O_RDONLY);
if (fd < 0) {
PLOG(WARNING) << "Failed to open " << path;
return false;
}
fd_ = fd;
return true;
}
bool GpioDriverSysfs::SetValue(bool val) {
if (val)
return Enable();
else
return Disable();
}
bool GpioDriverSysfs::GetValue(bool* val) {
std::string read_val;
if (!ReadFromFile(kValue, &read_val))
return false;
if (read_val.size() < 1) {
return false;
}
// Remove any whitespace.
read_val = read_val[0];
if (read_val == kValueHigh)
*val = true;
else
*val = false;
return true;
}
bool GpioDriverSysfs::SetDirection(GpioDirection direction) {
switch (direction) {
case kDirectionIn:
return WriteToFile(kDirection, kDirIn);
case kDirectionOutInitiallyHigh:
return WriteToFile(kDirection, kDirHigh);
case kDirectionOutInitiallyLow:
return WriteToFile(kDirection, kDirLow);
}
return false;
}
bool GpioDriverSysfs::SetActiveType(GpioActiveType type) {
if (type == kActiveLow) {
return WriteToFile(kActiveLowFile, kValueLow);
} else if (type == kActiveHigh) {
return WriteToFile(kActiveLowFile, kValueHigh);
}
return false;
}
bool GpioDriverSysfs::SetEdgeType(GpioEdgeType type) {
switch (type) {
case kEdgeNone:
return WriteToFile(kEdge, kEdgeNoneValue);
case kEdgeRising:
return WriteToFile(kEdge, kEdgeRisingValue);
case kEdgeFalling:
return WriteToFile(kEdge, kEdgeFallingValue);
case kEdgeBoth:
return WriteToFile(kEdge, kEdgeBothValue);
}
return false;
}
bool GpioDriverSysfs::GetPollingFd(ScopedFd* fd) {
int f = openat(fd_, kValue, O_RDWR);
if (f < 0)
return false;
fd->reset(f);
return true;
}
bool GpioDriverSysfs::Enable() {
return WriteToFile(kValue, kValueHigh);
}
bool GpioDriverSysfs::Disable() {
return WriteToFile(kValue, kValueLow);
}
bool GpioDriverSysfs::WriteToFile(const std::string& file,
const std::string& value) {
int fd = openat(fd_, file.c_str(), O_RDWR);
if (fd < 0)
return false;
ssize_t bytes = write(fd, value.c_str(), value.size());
close(fd);
if (bytes < 0)
return false;
if ((size_t)bytes != value.size())
return false;
return true;
}
bool GpioDriverSysfs::ReadFromFile(const std::string& file,
std::string* value) {
int fd = openat(fd_, file.c_str(), O_RDONLY);
if (fd < 0)
return false;
char tmp_buf[16] = "";
ssize_t bytes = read(fd, tmp_buf, sizeof(tmp_buf));
close(fd);
if (bytes < 0)
return false;
value->assign(tmp_buf, bytes);
return true;
}
bool GpioDriverSysfs::ExportGpio(uint32_t index) {
// Check if the pin is already exported.
// It will fail otherwise.
std::string path = kSysfsGpioPathPrefix + std::to_string(index);
struct stat stat_buf;
if (!stat(path.c_str(), &stat_buf))
return true;
int fd = open(kSysfsGpioExportPath, O_WRONLY);
if (fd < 0) {
PLOG(WARNING) << "Failed to open " << kSysfsGpioExportPath;
return false;
}
std::string value = std::to_string(index);
ssize_t bytes = write(fd, value.c_str(), value.size());
close(fd);
if (bytes < 0) {
PLOG(WARNING) << "Failed to write " << bytes;
return false;
}
if ((size_t)bytes != value.size())
return false;
return true;
}
} // namespace android
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