rtc: Move RTC function prototypes to their own header

softmmu/rtc.c defines two public functions: qemu_get_timedate() and
qemu_timedate_diff().  Currently we keep the prototypes for these in
qemu-common.h, but most files don't need them.  Move them to their
own header, a new include/sysemu/rtc.h.

Since the C files using these two functions did not need to include
qemu-common.h for any other reason, we can remove those include lines
when we add the include of the new rtc.h.

The license for the .h file follows that of the softmmu/rtc.c
where both the functions are defined.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

2 files changed, 58 insertions, 3 deletions

diff --git a/include/qemu-common.h b/include/qemu-common.h
index 0e7e7ba..68b2e3b 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -26,9 +26,6 @@
 int qemu_main(int argc, char **argv, char **envp);
 #endif
 
-void qemu_get_timedate(struct tm *tm, int offset);
-int qemu_timedate_diff(struct tm *tm);
-
 void *qemu_oom_check(void *ptr);
 
 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
diff --git a/include/sysemu/rtc.h b/include/sysemu/rtc.h
new file mode 100644
index 0000000..159702b
--- /dev/null
+++ b/include/sysemu/rtc.h
@@ -0,0 +1,58 @@
+/*
+ * RTC configuration and clock read
+ *
+ * Copyright (c) 2003-2021 QEMU contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef SYSEMU_RTC_H
+#define SYSEMU_RTC_H
+
+/**
+ * qemu_get_timedate: Get the current RTC time
+ * @tm: struct tm to fill in with RTC time
+ * @offset: offset in seconds to adjust the RTC time by before
+ *          converting to struct tm format.
+ *
+ * This function fills in @tm with the current RTC time, as adjusted
+ * by @offset (for example, if @offset is 3600 then the returned time/date
+ * will be one hour further ahead than the current RTC time).
+ *
+ * The usual use is by RTC device models, which should call this function
+ * to find the time/date value that they should return to the guest
+ * when it reads the RTC registers.
+ *
+ * The behaviour of the clock whose value this function returns will
+ * depend on the -rtc command line option passed by the user.
+ */
+void qemu_get_timedate(struct tm *tm, int offset);
+
+/**
+ * qemu_timedate_diff: Return difference between a struct tm and the RTC
+ * @tm: struct tm containing the date/time to compare against
+ *
+ * Returns the difference in seconds between the RTC clock time
+ * and the date/time specified in @tm. For example, if @tm specifies
+ * a timestamp one hour further ahead than the current RTC time
+ * then this function will return 3600.
+ */
+int qemu_timedate_diff(struct tm *tm);
+
+#endif