i2c.cpp - openbmc/google-ipmi-i2c - Gitiles

 /*
  * Copyright 2018 Google Inc.
  *
  * 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 "i2c.hpp"

 #include <fcntl.h>
 #include <linux/i2c-dev.h>
 #include <linux/i2c.h>
 #include <sys/ioctl.h>
 #include <unistd.h>

 #include <array>
 #include <cerrno>
 #include <cstdio>
 #include <cstring>
 #include <ipmid/api-types.hpp>
 #include <ipmid/handler.hpp>
 #include <ipmid/iana.hpp>
 #include <ipmid/oemopenbmc.hpp>
 #include <memory>
 #include <span>

 namespace oem
 {
 namespace i2c
 {

 // Instance object.
 std::unique_ptr<I2c> globalOemI2c;

 // Block read (I2C_M_RECV_LEN) reads count byte, then that many bytes,
 // then possibly a checksum byte. The specified byte count limit,
 // I2C_SMBUS_BLOCK_MAX, is 32, but it seems intractible to prove
 // every I2C implementation uses that limit. So to prevent overflow,
 // allocate buffers based on the largest possible count byte of 255.
 constexpr size_t maxRecvLenBuf = 1 + 255 + 1;
 typedef std::array<uint8_t, maxRecvLenBuf> BlockBuf;

 struct ParsedStep
 {
     std::span<const uint8_t> reqData;
     size_t length;
     DevAddr devAddr;
     bool isRead;
     // When nonzero, device supplies count for this step, as in SMBUS block
     // mode. Value will tell driver how many extra bytes to read for entire
     // block: 1 for count byte w/o PEC, 2 if there is also a PEC byte.
     uint16_t blockExtra;
     bool noStart;
 };

 struct ParsedReq
 {
     BusId localbus;
     bool usePec;
     size_t numSteps;
     std::array<ParsedStep, maxSteps> step;
 };

 ipmi::Cc parseReqHdr(std::span<const uint8_t> data, size_t* bytesUsed,
                      i2c::ParsedReq* req)
 {
     // Request header selects bus & flags for operation;
     // additional bytes beyond are to be interpreted as steps.
     if (data.size() < *bytesUsed + requestHeaderLen)
     {
         std::fprintf(stderr, "i2c::parse reqLen=%zu?\n", data.size());
         return ipmi::ccReqDataLenInvalid;
     }
     // Deserialize request header bytes.
     req->localbus = data[requestHeaderBus];
     auto reqFlags = data[requestHeaderFlags];
     *bytesUsed += requestHeaderLen;

     // Decode flags.
     req->usePec = !!(reqFlags & requestFlagsUsePec);
     return ipmi::ccSuccess;
 }

 ipmi::Cc parseReqStep(std::span<const uint8_t> data, size_t* bytesUsed,
                       i2c::ParsedReq* req)
 {
     size_t bytesLeft = data.size() - *bytesUsed;
     if (req->numSteps >= maxSteps || bytesLeft < stepHeaderLen)
     {
         std::fprintf(stderr, "i2c::parse[%zu] bytesLeft=%zu?\n", req->numSteps,
                      bytesLeft);
         return ipmi::ccReqDataLenInvalid;
     }
     const std::span<const uint8_t> stepHdr = data.subspan(*bytesUsed);
     auto step = &req->step[req->numSteps++];

     // Deserialize request step header bytes.
     uint8_t devAndDir = stepHdr[stepHeaderDevAndDir];
     uint8_t stepFlags = stepHdr[stepHeaderFlags];
     step->length = stepHdr[stepHeaderParm];
     bytesLeft -= stepHeaderLen;
     *bytesUsed += stepHeaderLen;

     // Decode device addr & direction.
     step->devAddr = devAndDir >> 1;
     step->isRead = !!(devAndDir & 1);

     // Decode step flags.
     step->noStart = !!(stepFlags & stepFlagsNoStart);

     if (step->isRead)
     {
         // Read could select blockExtra.
         if (stepFlags & stepFlagsRecvLen)
         {
             step->blockExtra = req->usePec ? 2 : 1;
         }
     }
     else
     {
         // For write, requested byte count must follow.
         if (bytesLeft < step->length)
         {
             std::fprintf(stderr, "i2c::parse[%zu] bytesLeft=%zu, parm=%zu?\n",
                          req->numSteps, bytesLeft, step->length);
             return ipmi::ccReqDataLenInvalid;
         }
         step->reqData = data.subspan(*bytesUsed);
         *bytesUsed += step->length;
     }
     return ipmi::ccSuccess;
 }

 // Parse i2c request.
 ipmi::Cc parse(std::span<const uint8_t> data, i2c::ParsedReq* req)
 {
     size_t bytesUsed = 0;
     auto rc = parseReqHdr(data, &bytesUsed, req);
     if (rc != ipmi::ccSuccess)
     {
         return rc;
     }
     do
     {
         rc = parseReqStep(data, &bytesUsed, req);
         if (rc != ipmi::ccSuccess)
         {
             return rc;
         }
     } while (bytesUsed < data.size());
     return ipmi::ccSuccess;
 }

 // Convert parsed request to I2C messages.
 static ipmi::Cc buildI2cMsgs(const i2c::ParsedReq& req,
                              std::unique_ptr<i2c::BlockBuf> rxBuf[],
                              struct i2c_msg msgs[],
                              struct i2c_rdwr_ioctl_data* msgset)
 {
     size_t minReplyLen = 0;

     for (size_t i = 0; i < req.numSteps; ++msgset->nmsgs, ++i)
     {
         const auto& step = req.step[i];
         auto* msg = &msgs[i];
         msg->addr = step.devAddr;

         if (!step.isRead)
         {
             msg->flags = 0;
             msg->len = step.length;
             msg->buf = const_cast<uint8_t*>(step.reqData.data());
             continue;
         }
         rxBuf[i] = std::make_unique<i2c::BlockBuf>();
         msg->buf = rxBuf[i]->data();

         if (step.blockExtra == 0)
         {
             msg->flags = I2C_M_RD;
             msg->len = step.length;
             minReplyLen += msg->len;
         }
         else
         {
             // Special buffer setup needed for block read:
             // . 1. msg len must allow for maximum possible transfer,
             // . 2. blockExtra must be preloaded into buf[0]
             // The internal i2c_transfer API is slightly different;
             // the rdwr ioctl handler adapts by moving blockExtra
             // into msg.len where the driver will expect to find it.
             //
             // References:
             //  drivers/i2c/i2c-dev.c: i2cdev_ioctl_rdwr()
             msg->flags = I2C_M_RD | I2C_M_RECV_LEN;
             msg->len = maxRecvLenBuf;
             msg->buf[0] = step.blockExtra;
             minReplyLen += step.blockExtra;
         }
     }

     if (minReplyLen > i2c::largestReply)
     {
         std::fprintf(stderr, "I2c::transfer minReplyLen=%zu?\n", minReplyLen);
         return ipmi::ccResponseError; // Won't fit in response message
     }

 #ifdef __IPMI_DEBUG__
     for (size_t i = 0; i < req.numSteps; ++i)
     {
         auto* msg = &msgs[i];
         std::fprintf(stderr, "I2c::transfer msg[%zu]: %02x %04x %d\n", i,
                      msg->addr, msg->flags, msg->len);
     }
 #endif

     return ipmi::ccSuccess;
 }

 static int openBus(BusId localbus)
 {
     char busCharDev[16];
     std::snprintf(busCharDev, sizeof(busCharDev) - 1, "/dev/i2c-%d", localbus);
     int busFd = open(busCharDev, O_RDWR);
     if (busFd < 0)
     {
         std::fprintf(stderr,
                      "NetFn:[0x2E], OEM:[0x002B79], Cmd:[0x02], "
                      "I2C Bus Open(\"%s\"): \"%s\"\n",
                      busCharDev, strerror(-busFd));
     }
     return busFd;
 }

 } // namespace i2c

 Resp I2c::transfer(::ipmi::Context::ptr, std::span<const uint8_t> data)
 {
     // Parse message header.
     i2c::ParsedReq req = {};
     auto rc = parse(data, &req);
     if (rc != ipmi::ccSuccess)
     {
         return ipmi::response(rc);
     }

     // Build full msgset
     std::unique_ptr<i2c::BlockBuf> rxBuf[i2c::maxSteps];
     struct i2c_msg msgs[i2c::maxSteps] = {};
     struct i2c_rdwr_ioctl_data msgset = {
         .msgs = msgs,
         .nmsgs = 0,
     };
     rc = buildI2cMsgs(req, rxBuf, msgs, &msgset);
     if (rc != ipmi::ccSuccess)
     {
         return ipmi::response(rc);
     }

     // Try to open i2c bus
     int busFd = i2c::openBus(req.localbus);
     if (busFd < 0)
     {
         return ipmi::responseUnspecifiedError();
     }
     int ioError = ioctl(busFd, I2C_RDWR, &msgset);

     // Done with busFd, so close it immediately to avoid leaking it.
     (void)close(busFd);
     if (ioError < 0)
     {
         std::fprintf(stderr, "I2c::transfer I2C_RDWR ioError=%d?\n", ioError);
         return ipmi::responseUnspecifiedError(); // I2C_RDWR I/O error
     }

     // If we read any data, append it, in the order we read it.
     std::vector<uint8_t> output;
     size_t replyLen = 0;
     for (size_t i = 0; i < req.numSteps; ++i)
     {
         const auto& step = req.step[i];
         if (step.isRead)
         {
             const auto* msg = &msgs[i];
             size_t lenRead =
                 step.blockExtra ? *msg->buf + step.blockExtra : msg->len;
             replyLen += lenRead;
             if (replyLen > i2c::largestReply)
             {
                 std::fprintf(stderr, "I2c::transfer[%zu] replyLen=%zu?\n", i,
                              replyLen);
                 return ipmi::responseUnspecifiedError(); // Won't fit in
                                                          // response message
             }
             output.resize(output.size() + lenRead);
             std::memcpy(output.data() + output.size() - lenRead, msg->buf,
                         lenRead);
         }
     }
     return ::ipmi::responseSuccess(output);
 }

 void I2c::registerOemRouter()
 {
     auto handler = [this](ipmi::Context::ptr ctx, std::vector<uint8_t> data) {
         return transfer(ctx, data);
     };

     std::fprintf(stderr, "Registering OEM:[%#08X], Cmd:[%#04X] for I2C\n",
                  googOemNumber, Cmd::i2cCmd);
     ipmi::registerOemHandler(::ipmi::prioOemBase, oem::googOemNumber,
                              Cmd::i2cCmd, ::ipmi::Privilege::User, handler);

     std::fprintf(stderr, "Registering OEM:[%#08X], Cmd:[%#04X] for I2C\n",
                  obmcOemNumber, Cmd::i2cCmd);
     ipmi::registerOemHandler(::ipmi::prioOemBase, oem::obmcOemNumber,
                              Cmd::i2cCmd, ::ipmi::Privilege::User, handler);
 }

 namespace i2c
 {
 // Currently ipmid dynamically loads providers such as these;
 // this creates our singleton upon load.
 void setupGlobalOemI2c() __attribute__((constructor));

 void setupGlobalOemI2c()
 {
     globalOemI2c = std::make_unique<I2c>();
     globalOemI2c->registerOemRouter();
 }
 } // namespace i2c
 } // namespace oem
	/*
	* Copyright 2018 Google Inc.
	*
	* 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 "i2c.hpp"

	#include <fcntl.h>
	#include <linux/i2c-dev.h>
	#include <linux/i2c.h>
	#include <sys/ioctl.h>
	#include <unistd.h>

	#include <array>
	#include <cerrno>
	#include <cstdio>
	#include <cstring>
	#include <ipmid/api-types.hpp>
	#include <ipmid/handler.hpp>
	#include <ipmid/iana.hpp>
	#include <ipmid/oemopenbmc.hpp>
	#include <memory>
	#include <span>

	namespace oem
	{
	namespace i2c
	{

	// Instance object.
	std::unique_ptr<I2c> globalOemI2c;

	// Block read (I2C_M_RECV_LEN) reads count byte, then that many bytes,
	// then possibly a checksum byte. The specified byte count limit,
	// I2C_SMBUS_BLOCK_MAX, is 32, but it seems intractible to prove
	// every I2C implementation uses that limit. So to prevent overflow,
	// allocate buffers based on the largest possible count byte of 255.
	constexpr size_t maxRecvLenBuf = 1 + 255 + 1;
	typedef std::array<uint8_t, maxRecvLenBuf> BlockBuf;

	struct ParsedStep
	{
	std::span<const uint8_t> reqData;
	size_t length;
	DevAddr devAddr;
	bool isRead;
	// When nonzero, device supplies count for this step, as in SMBUS block
	// mode. Value will tell driver how many extra bytes to read for entire
	// block: 1 for count byte w/o PEC, 2 if there is also a PEC byte.
	uint16_t blockExtra;
	bool noStart;
	};

	struct ParsedReq
	{
	BusId localbus;
	bool usePec;
	size_t numSteps;
	std::array<ParsedStep, maxSteps> step;
	};

	ipmi::Cc parseReqHdr(std::span<const uint8_t> data, size_t* bytesUsed,
	i2c::ParsedReq* req)
	{
	// Request header selects bus & flags for operation;
	// additional bytes beyond are to be interpreted as steps.
	if (data.size() < *bytesUsed + requestHeaderLen)
	{
	std::fprintf(stderr, "i2c::parse reqLen=%zu?\n", data.size());
	return ipmi::ccReqDataLenInvalid;
	}
	// Deserialize request header bytes.
	req->localbus = data[requestHeaderBus];
	auto reqFlags = data[requestHeaderFlags];
	*bytesUsed += requestHeaderLen;

	// Decode flags.
	req->usePec = !!(reqFlags & requestFlagsUsePec);
	return ipmi::ccSuccess;
	}

	ipmi::Cc parseReqStep(std::span<const uint8_t> data, size_t* bytesUsed,
	i2c::ParsedReq* req)
	{
	size_t bytesLeft = data.size() - *bytesUsed;
	if (req->numSteps >= maxSteps \|\| bytesLeft < stepHeaderLen)
	{
	std::fprintf(stderr, "i2c::parse[%zu] bytesLeft=%zu?\n", req->numSteps,
	bytesLeft);
	return ipmi::ccReqDataLenInvalid;
	}
	const std::span<const uint8_t> stepHdr = data.subspan(*bytesUsed);
	auto step = &req->step[req->numSteps++];

	// Deserialize request step header bytes.
	uint8_t devAndDir = stepHdr[stepHeaderDevAndDir];
	uint8_t stepFlags = stepHdr[stepHeaderFlags];
	step->length = stepHdr[stepHeaderParm];
	bytesLeft -= stepHeaderLen;
	*bytesUsed += stepHeaderLen;

	// Decode device addr & direction.
	step->devAddr = devAndDir >> 1;
	step->isRead = !!(devAndDir & 1);

	// Decode step flags.
	step->noStart = !!(stepFlags & stepFlagsNoStart);

	if (step->isRead)
	{
	// Read could select blockExtra.
	if (stepFlags & stepFlagsRecvLen)
	{
	step->blockExtra = req->usePec ? 2 : 1;
	}
	}
	else
	{
	// For write, requested byte count must follow.
	if (bytesLeft < step->length)
	{
	std::fprintf(stderr, "i2c::parse[%zu] bytesLeft=%zu, parm=%zu?\n",
	req->numSteps, bytesLeft, step->length);
	return ipmi::ccReqDataLenInvalid;
	}
	step->reqData = data.subspan(*bytesUsed);
	*bytesUsed += step->length;
	}
	return ipmi::ccSuccess;
	}

	// Parse i2c request.
	ipmi::Cc parse(std::span<const uint8_t> data, i2c::ParsedReq* req)
	{
	size_t bytesUsed = 0;
	auto rc = parseReqHdr(data, &bytesUsed, req);
	if (rc != ipmi::ccSuccess)
	{
	return rc;
	}
	do
	{
	rc = parseReqStep(data, &bytesUsed, req);
	if (rc != ipmi::ccSuccess)
	{
	return rc;
	}
	} while (bytesUsed < data.size());
	return ipmi::ccSuccess;
	}

	// Convert parsed request to I2C messages.
	static ipmi::Cc buildI2cMsgs(const i2c::ParsedReq& req,
	std::unique_ptr<i2c::BlockBuf> rxBuf[],
	struct i2c_msg msgs[],
	struct i2c_rdwr_ioctl_data* msgset)
	{
	size_t minReplyLen = 0;

	for (size_t i = 0; i < req.numSteps; ++msgset->nmsgs, ++i)
	{
	const auto& step = req.step[i];
	auto* msg = &msgs[i];
	msg->addr = step.devAddr;

	if (!step.isRead)
	{
	msg->flags = 0;
	msg->len = step.length;
	msg->buf = const_cast<uint8_t*>(step.reqData.data());
	continue;
	}
	rxBuf[i] = std::make_unique<i2c::BlockBuf>();
	msg->buf = rxBuf[i]->data();

	if (step.blockExtra == 0)
	{
	msg->flags = I2C_M_RD;
	msg->len = step.length;
	minReplyLen += msg->len;
	}
	else
	{
	// Special buffer setup needed for block read:
	// . 1. msg len must allow for maximum possible transfer,
	// . 2. blockExtra must be preloaded into buf[0]
	// The internal i2c_transfer API is slightly different;
	// the rdwr ioctl handler adapts by moving blockExtra
	// into msg.len where the driver will expect to find it.
	//
	// References:
	// drivers/i2c/i2c-dev.c: i2cdev_ioctl_rdwr()
	msg->flags = I2C_M_RD \| I2C_M_RECV_LEN;
	msg->len = maxRecvLenBuf;
	msg->buf[0] = step.blockExtra;
	minReplyLen += step.blockExtra;
	}
	}

	if (minReplyLen > i2c::largestReply)
	{
	std::fprintf(stderr, "I2c::transfer minReplyLen=%zu?\n", minReplyLen);
	return ipmi::ccResponseError; // Won't fit in response message
	}

	#ifdef __IPMI_DEBUG__
	for (size_t i = 0; i < req.numSteps; ++i)
	{
	auto* msg = &msgs[i];
	std::fprintf(stderr, "I2c::transfer msg[%zu]: %02x %04x %d\n", i,
	msg->addr, msg->flags, msg->len);
	}
	#endif

	return ipmi::ccSuccess;
	}

	static int openBus(BusId localbus)
	{
	char busCharDev[16];
	std::snprintf(busCharDev, sizeof(busCharDev) - 1, "/dev/i2c-%d", localbus);
	int busFd = open(busCharDev, O_RDWR);
	if (busFd < 0)
	{
	std::fprintf(stderr,
	"NetFn:[0x2E], OEM:[0x002B79], Cmd:[0x02], "
	"I2C Bus Open(\"%s\"): \"%s\"\n",
	busCharDev, strerror(-busFd));
	}
	return busFd;
	}

	} // namespace i2c

	Resp I2c::transfer(::ipmi::Context::ptr, std::span<const uint8_t> data)
	{
	// Parse message header.
	i2c::ParsedReq req = {};
	auto rc = parse(data, &req);
	if (rc != ipmi::ccSuccess)
	{
	return ipmi::response(rc);
	}

	// Build full msgset
	std::unique_ptr<i2c::BlockBuf> rxBuf[i2c::maxSteps];
	struct i2c_msg msgs[i2c::maxSteps] = {};
	struct i2c_rdwr_ioctl_data msgset = {
	.msgs = msgs,
	.nmsgs = 0,
	};
	rc = buildI2cMsgs(req, rxBuf, msgs, &msgset);
	if (rc != ipmi::ccSuccess)
	{
	return ipmi::response(rc);
	}

	// Try to open i2c bus
	int busFd = i2c::openBus(req.localbus);
	if (busFd < 0)
	{
	return ipmi::responseUnspecifiedError();
	}
	int ioError = ioctl(busFd, I2C_RDWR, &msgset);

	// Done with busFd, so close it immediately to avoid leaking it.
	(void)close(busFd);
	if (ioError < 0)
	{
	std::fprintf(stderr, "I2c::transfer I2C_RDWR ioError=%d?\n", ioError);
	return ipmi::responseUnspecifiedError(); // I2C_RDWR I/O error
	}

	// If we read any data, append it, in the order we read it.
	std::vector<uint8_t> output;
	size_t replyLen = 0;
	for (size_t i = 0; i < req.numSteps; ++i)
	{
	const auto& step = req.step[i];
	if (step.isRead)
	{
	const auto* msg = &msgs[i];
	size_t lenRead =
	step.blockExtra ? *msg->buf + step.blockExtra : msg->len;
	replyLen += lenRead;
	if (replyLen > i2c::largestReply)
	{
	std::fprintf(stderr, "I2c::transfer[%zu] replyLen=%zu?\n", i,
	replyLen);
	return ipmi::responseUnspecifiedError(); // Won't fit in
	// response message
	}
	output.resize(output.size() + lenRead);
	std::memcpy(output.data() + output.size() - lenRead, msg->buf,
	lenRead);
	}
	}
	return ::ipmi::responseSuccess(output);
	}

	void I2c::registerOemRouter()
	{
	auto handler = [this](ipmi::Context::ptr ctx, std::vector<uint8_t> data) {
	return transfer(ctx, data);
	};

	std::fprintf(stderr, "Registering OEM:[%#08X], Cmd:[%#04X] for I2C\n",
	googOemNumber, Cmd::i2cCmd);
	ipmi::registerOemHandler(::ipmi::prioOemBase, oem::googOemNumber,
	Cmd::i2cCmd, ::ipmi::Privilege::User, handler);

	std::fprintf(stderr, "Registering OEM:[%#08X], Cmd:[%#04X] for I2C\n",
	obmcOemNumber, Cmd::i2cCmd);
	ipmi::registerOemHandler(::ipmi::prioOemBase, oem::obmcOemNumber,
	Cmd::i2cCmd, ::ipmi::Privilege::User, handler);
	}

	namespace i2c
	{
	// Currently ipmid dynamically loads providers such as these;
	// this creates our singleton upon load.
	void setupGlobalOemI2c() __attribute__((constructor));

	void setupGlobalOemI2c()
	{
	globalOemI2c = std::make_unique<I2c>();
	globalOemI2c->registerOemRouter();
	}
	} // namespace i2c
	} // namespace oem