Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 301 insertions, 0 deletions

diff --git a/include/hw/ptimer.h b/include/hw/ptimer.h
new file mode 100644
index 000000000..c44321847
--- /dev/null
+++ b/include/hw/ptimer.h
@@ -0,0 +1,301 @@
+/*
+ * General purpose implementation of a simple periodic countdown timer.
+ *
+ * Copyright (c) 2007 CodeSourcery.
+ *
+ * This code is licensed under the GNU LGPL.
+ */
+#ifndef PTIMER_H
+#define PTIMER_H
+
+#include "qemu/timer.h"
+
+/*
+ * The ptimer API implements a simple periodic countdown timer.
+ * The countdown timer has a value (which can be read and written via
+ * ptimer_get_count() and ptimer_set_count()). When it is enabled
+ * using ptimer_run(), the value will count downwards at the frequency
+ * which has been configured using ptimer_set_period() or ptimer_set_freq().
+ * When it reaches zero it will trigger a callback function, and
+ * can be set to either reload itself from a specified limit value
+ * and keep counting down, or to stop (as a one-shot timer).
+ *
+ * A transaction-based API is used for modifying ptimer state: all calls
+ * to functions which modify ptimer state must be between matched calls to
+ * ptimer_transaction_begin() and ptimer_transaction_commit().
+ * When ptimer_transaction_commit() is called it will evaluate the state
+ * of the timer after all the changes in the transaction, and call the
+ * callback if necessary. (See the ptimer_init() documentation for the full
+ * list of state-modifying functions and detailed semantics of the callback.)
+ *
+ * Forgetting to set the period/frequency (or setting it to zero) is a
+ * bug in the QEMU device and will cause warning messages to be printed
+ * to stderr when the guest attempts to enable the timer.
+ */
+
+/* The default ptimer policy retains backward compatibility with the legacy
+ * timers. Custom policies are adjusting the default one. Consider providing
+ * a correct policy for your timer.
+ *
+ * The rough edges of the default policy:
+ *  - Starting to run with a period = 0 emits error message and stops the
+ *    timer without a trigger.
+ *
+ *  - Setting period to 0 of the running timer emits error message and
+ *    stops the timer without a trigger.
+ *
+ *  - Starting to run with counter = 0 or setting it to "0" while timer
+ *    is running causes a trigger and reloads counter with a limit value.
+ *    If limit = 0, ptimer emits error message and stops the timer.
+ *
+ *  - Counter value of the running timer is one less than the actual value.
+ *
+ *  - Changing period/frequency of the running timer loses time elapsed
+ *    since the last period, effectively restarting the timer with a
+ *    counter = counter value at the moment of change (.i.e. one less).
+ */
+#define PTIMER_POLICY_DEFAULT               0
+
+/* Periodic timer counter stays with "0" for a one period before wrapping
+ * around.  */
+#define PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD (1 << 0)
+
+/* Running periodic timer that has counter = limit = 0 would continuously
+ * re-trigger every period.  */
+#define PTIMER_POLICY_CONTINUOUS_TRIGGER    (1 << 1)
+
+/* Starting to run with/setting counter to "0" won't trigger immediately,
+ * but after a one period for both oneshot and periodic modes.  */
+#define PTIMER_POLICY_NO_IMMEDIATE_TRIGGER  (1 << 2)
+
+/* Starting to run with/setting counter to "0" won't re-load counter
+ * immediately, but after a one period.  */
+#define PTIMER_POLICY_NO_IMMEDIATE_RELOAD   (1 << 3)
+
+/* Make counter value of the running timer represent the actual value and
+ * not the one less.  */
+#define PTIMER_POLICY_NO_COUNTER_ROUND_DOWN (1 << 4)
+
+/*
+ * Starting to run with a zero counter, or setting the counter to "0" via
+ * ptimer_set_count() or ptimer_set_limit() will not trigger the timer
+ * (though it will cause a reload). Only a counter decrement to "0"
+ * will cause a trigger. Not compatible with NO_IMMEDIATE_TRIGGER;
+ * ptimer_init() will assert() that you don't set both.
+ */
+#define PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT (1 << 5)
+
+/* ptimer.c */
+typedef struct ptimer_state ptimer_state;
+typedef void (*ptimer_cb)(void *opaque);
+
+/**
+ * ptimer_init - Allocate and return a new ptimer
+ * @callback: function to call on ptimer expiry
+ * @callback_opaque: opaque pointer passed to @callback
+ * @policy: PTIMER_POLICY_* bits specifying behaviour
+ *
+ * The ptimer returned must be freed using ptimer_free().
+ *
+ * If a ptimer is created using this API then will use the
+ * transaction-based API for modifying ptimer state: all calls
+ * to functions which modify ptimer state:
+ *  - ptimer_set_period()
+ *  - ptimer_set_freq()
+ *  - ptimer_set_limit()
+ *  - ptimer_set_count()
+ *  - ptimer_run()
+ *  - ptimer_stop()
+ * must be between matched calls to ptimer_transaction_begin()
+ * and ptimer_transaction_commit(). When ptimer_transaction_commit()
+ * is called it will evaluate the state of the timer after all the
+ * changes in the transaction, and call the callback if necessary.
+ *
+ * The callback function is always called from within a transaction
+ * begin/commit block, so the callback should not call the
+ * ptimer_transaction_begin() function itself. If the callback changes
+ * the ptimer state such that another ptimer expiry is triggered, then
+ * the callback will be called a second time after the first call returns.
+ */
+ptimer_state *ptimer_init(ptimer_cb callback,
+                          void *callback_opaque,
+                          uint8_t policy_mask);
+
+/**
+ * ptimer_free - Free a ptimer
+ * @s: timer to free
+ *
+ * Free a ptimer created using ptimer_init().
+ */
+void ptimer_free(ptimer_state *s);
+
+/**
+ * ptimer_transaction_begin() - Start a ptimer modification transaction
+ *
+ * This function must be called before making any calls to functions
+ * which modify the ptimer's state (see the ptimer_init() documentation
+ * for a list of these), and must always have a matched call to
+ * ptimer_transaction_commit().
+ * It is an error to call this function for a BH-based ptimer;
+ * attempting to do this will trigger an assert.
+ */
+void ptimer_transaction_begin(ptimer_state *s);
+
+/**
+ * ptimer_transaction_commit() - Commit a ptimer modification transaction
+ *
+ * This function must be called after calls to functions which modify
+ * the ptimer's state, and completes the update of the ptimer. If the
+ * ptimer state now means that we should trigger the timer expiry
+ * callback, it will be called directly.
+ */
+void ptimer_transaction_commit(ptimer_state *s);
+
+/**
+ * ptimer_set_period - Set counter increment interval in nanoseconds
+ * @s: ptimer to configure
+ * @period: period of the counter in nanoseconds
+ *
+ * Note that if your counter behaviour is specified as having a
+ * particular frequency rather than a period then ptimer_set_freq()
+ * may be more appropriate.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_set_period(ptimer_state *s, int64_t period);
+
+/**
+ * ptimer_set_period_from_clock - Set counter increment from a Clock
+ * @s: ptimer to configure
+ * @clk: pointer to Clock object to take period from
+ * @divisor: value to scale the clock frequency down by
+ *
+ * If the ptimer is being driven from a Clock, this is the preferred
+ * way to tell the ptimer about the period, because it avoids any
+ * possible rounding errors that might happen if the internal
+ * representation of the Clock period was converted to either a period
+ * in ns or a frequency in Hz.
+ *
+ * If the ptimer should run at the same frequency as the clock,
+ * pass 1 as the @divisor; if the ptimer should run at half the
+ * frequency, pass 2, and so on.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_set_period_from_clock(ptimer_state *s, const Clock *clock,
+                                  unsigned int divisor);
+
+/**
+ * ptimer_set_freq - Set counter frequency in Hz
+ * @s: ptimer to configure
+ * @freq: counter frequency in Hz
+ *
+ * This does the same thing as ptimer_set_period(), so you only
+ * need to call one of them. If the counter behaviour is specified
+ * as setting the frequency then this function is more appropriate,
+ * because it allows specifying an effective period which is
+ * precise to fractions of a nanosecond, avoiding rounding errors.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_set_freq(ptimer_state *s, uint32_t freq);
+
+/**
+ * ptimer_get_limit - Get the configured limit of the ptimer
+ * @s: ptimer to query
+ *
+ * This function returns the current limit (reload) value
+ * of the down-counter; that is, the value which it will be
+ * reset to when it hits zero.
+ *
+ * Generally timer devices using ptimers should be able to keep
+ * their reload register state inside the ptimer using the get
+ * and set limit functions rather than needing to also track it
+ * in their own state structure.
+ */
+uint64_t ptimer_get_limit(ptimer_state *s);
+
+/**
+ * ptimer_set_limit - Set the limit of the ptimer
+ * @s: ptimer
+ * @limit: initial countdown value
+ * @reload: if nonzero, then reset the counter to the new limit
+ *
+ * Set the limit value of the down-counter. The @reload flag can
+ * be used to emulate the behaviour of timers which immediately
+ * reload the counter when their reload register is written to.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload);
+
+/**
+ * ptimer_get_count - Get the current value of the ptimer
+ * @s: ptimer
+ *
+ * Return the current value of the down-counter. This will
+ * return the correct value whether the counter is enabled or
+ * disabled.
+ */
+uint64_t ptimer_get_count(ptimer_state *s);
+
+/**
+ * ptimer_set_count - Set the current value of the ptimer
+ * @s: ptimer
+ * @count: count value to set
+ *
+ * Set the value of the down-counter. If the counter is currently
+ * enabled this will arrange for a timer callback at the appropriate
+ * point in the future.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_set_count(ptimer_state *s, uint64_t count);
+
+/**
+ * ptimer_run - Start a ptimer counting
+ * @s: ptimer
+ * @oneshot: non-zero if this timer should only count down once
+ *
+ * Start a ptimer counting down; when it reaches zero the callback function
+ * passed to ptimer_init() will be invoked.
+ * If the @oneshot argument is zero,
+ * the counter value will then be reloaded from the limit and it will
+ * start counting down again. If @oneshot is non-zero, then the counter
+ * will disable itself when it reaches zero.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_run(ptimer_state *s, int oneshot);
+
+/**
+ * ptimer_stop - Stop a ptimer counting
+ * @s: ptimer
+ *
+ * Pause a timer (the count stays at its current value until ptimer_run()
+ * is called to start it counting again).
+ *
+ * Note that this can cause it to "lose" time, even if it is immediately
+ * restarted.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_stop(ptimer_state *s);
+
+extern const VMStateDescription vmstate_ptimer;
+
+#define VMSTATE_PTIMER(_field, _state) \
+    VMSTATE_STRUCT_POINTER_V(_field, _state, 1, vmstate_ptimer, ptimer_state)
+
+#define VMSTATE_PTIMER_ARRAY(_f, _s, _n)                                \
+    VMSTATE_ARRAY_OF_POINTER_TO_STRUCT(_f, _s, _n, 0,                   \
+                                       vmstate_ptimer, ptimer_state)
+
+#endif