Gabe Black has uploaded this change for review. (
https://gem5-review.googlesource.com/c/public/gem5/+/66671?usp=email )
Change subject: dev: Introduce a reset() method on RegisterBank and
Register classes.
......................................................................
dev: Introduce a reset() method on RegisterBank and Register classes.
This will make it much easier to implement reset behaviors on devices
which have RegisterBanks in them.
Change-Id: I73fe9874fcb69feed33611a320dcca85c0de2d0e
---
M src/dev/reg_bank.hh
M src/dev/serial/uart8250.hh
2 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/src/dev/reg_bank.hh b/src/dev/reg_bank.hh
index 31c0ce5..66d668b 100644
--- a/src/dev/reg_bank.hh
+++ b/src/dev/reg_bank.hh
@@ -117,6 +117,11 @@
* RegisterBankLE and RegisterBankBE aliases to make it a little easier to
* refer to one or the other version.
*
+ * A RegisterBank also has a reset() method which will (by default) call
the
+ * reset() method on each register within it. This method is virtual, and
so
+ * can be overridden if something additional or different needs to be done
to
+ * reset the hardware model.
+ *
*
* == Register interface ==
*
@@ -145,6 +150,12 @@
* it still has to implement these methods, but they don't have to
actually do
* anything.
*
+ * Each register also has a "reset" method, which will reset the register
as
+ * if its containing device is being reset. By default, this will just
restore
+ * the initial value of the register, but can be overridden to implement
+ * additional behavior like resetting other aspects of the device which are
+ * controlled by the value of the register.
+ *
*
* == Basic Register types ==
*
@@ -360,6 +371,9 @@
// Methods for implementing serialization for checkpoints.
virtual void serialize(std::ostream &os) const = 0;
virtual bool unserialize(const std::string &s) = 0;
+
+ // Reset the register.
+ virtual void reset() = 0;
};
// Filler registers which return a fixed pattern.
@@ -388,6 +402,9 @@
void serialize(std::ostream &os) const override {}
bool unserialize(const std::string &s) override { return true; }
+
+ // Resetting a read only register doesn't need to do anything.
+ void reset() override {}
};
// Register which reads as all zeroes.
@@ -453,6 +470,10 @@
void serialize(std::ostream &os) const override {}
bool unserialize(const std::string &s) override { return true; }
+ // Assume since the buffer is managed externally, it will be reset
+ // externally.
+ void reset() override {}
+
protected:
/**
* This method exists so that derived classes that need to
initialize
@@ -516,6 +537,8 @@
return true;
}
+
+ void reset() override { buffer = std::array<uint8_t, BufBytes>{}; }
};
template <typename Data, ByteOrder RegByteOrder=BankByteOrder>
@@ -534,6 +557,7 @@
private:
Data _data = {};
+ Data _resetData = {};
Data _writeMask = mask(sizeof(Data) * 8);
ReadFunc _reader = defaultReader;
@@ -602,11 +626,13 @@
// Constructor and move constructor with an initial data value.
constexpr Register(const std::string &new_name, const Data
&new_data) :
- RegisterBase(new_name, sizeof(Data)), _data(new_data)
+ RegisterBase(new_name, sizeof(Data)), _data(new_data),
+ _resetData(new_data)
{}
constexpr Register(const std::string &new_name,
const Data &&new_data) :
- RegisterBase(new_name, sizeof(Data)), _data(new_data)
+ RegisterBase(new_name, sizeof(Data)), _data(new_data),
+ _resetData(new_data)
{}
// Set which bits of the register are writeable.
@@ -789,6 +815,9 @@
{
return ParseParam<Data>::parse(s, get());
}
+
+ // Reset our data to its initial value.
+ void reset() override { get() = _resetData; }
};
private:
@@ -984,6 +1013,14 @@
}
}
}
+
+ // By default, reset all the registers in the bank.
+ virtual void
+ reset()
+ {
+ for (auto &[offset, reg]: _offsetMap)
+ reg.get().reset();
+ }
};
using RegisterBankLE = RegisterBank<ByteOrder::little>;
diff --git a/src/dev/serial/uart8250.hh b/src/dev/serial/uart8250.hh
index c55d889..5774f78 100644
--- a/src/dev/serial/uart8250.hh
+++ b/src/dev/serial/uart8250.hh
@@ -113,6 +113,13 @@
void serialize(std::ostream &os) const override {}
bool unserialize(const std::string &s) override { return true;
}
+
+ void
+ reset() override
+ {
+ _reg1.reset();
+ _reg2.reset();
+ }
};
class BankedRegister : public PairedRegister
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I73fe9874fcb69feed33611a320dcca85c0de2d0e
Gerrit-Change-Number: 66671
Gerrit-PatchSet: 1
Gerrit-Owner: Gabe Black <gabe.bl...@gmail.com>
Gerrit-CC: Gabe Black <gabebl...@google.com>
Gerrit-MessageType: newchange
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