From dcda5731ecbbce70edeaa7662e9ea0fc190a1943 Mon Sep 17 00:00:00 2001
From: Miquel Sabaté Solà <mikisabate@gmail.com>
Date: Fri, 22 Nov 2024 15:46:59 +0100
Subject: Enable the timer from the SBI interface
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A basic interrupt handler has been implemented which tracks the seconds
that have been elapsing along the way. Depending on the value of these
seconds, then a task has to be called.

Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
---
 include/fbos/compiler.h | 2 ++
 include/fbos/init.h     | 9 +++++++++
 include/fbos/sbi.h      | 7 +++++++
 3 files changed, 18 insertions(+)

(limited to 'include')

diff --git a/include/fbos/compiler.h b/include/fbos/compiler.h
index c26c05c..95596dd 100644
--- a/include/fbos/compiler.h
+++ b/include/fbos/compiler.h
@@ -6,6 +6,8 @@
  */
 
 #define __noreturn __attribute__((__noreturn__))
+#define __s_interrupt __attribute__((interrupt("supervisor")))
+#define __aligned(x) __attribute__((aligned(x)))
 
 /*
  * Compiler attributes specific to linker sections.
diff --git a/include/fbos/init.h b/include/fbos/init.h
index 978eebe..711d2cf 100644
--- a/include/fbos/init.h
+++ b/include/fbos/init.h
@@ -3,10 +3,19 @@
 
 #include <fbos/compiler.h>
 
+// Tracks the amount of seconds that have elapsed since activating timer
+// interrupts.
+//
+// Instantiated in kernel/trap.c, initialized in main.c.
+extern uint64_t seconds_elapsed;
+
 // Extract the executables from the initrd that is located at `base_addr` and
 // has the given `size`.
 void extract_initrd(const unsigned char *const base_addr, uint64_t size);
 
+// Setup the interrupt vectors and the SBI timer.
+void setup_interrupts(void);
+
 // The entry point for the kernel.
 void start_kernel(void *dtb);
 
diff --git a/include/fbos/sbi.h b/include/fbos/sbi.h
index 2575415..b1c99ea 100644
--- a/include/fbos/sbi.h
+++ b/include/fbos/sbi.h
@@ -18,6 +18,7 @@ enum sbi_ret_error {
 // SBI extensions supported by this kernel.
 enum sbi_ext {
 	DBCN_EXT = 0x4442434E,
+	TIME_EXT = 0x54494D45,
 };
 
 // Function IDs for the Debug Console Extension "DBCN".
@@ -25,6 +26,11 @@ enum dbcn_actions {
 	DBCN_WRITE = 0x00,
 };
 
+// Function IDs for the Timer Extension "TIME".
+enum time_actions {
+	TIME_SET_TIMER = 0x00,
+};
+
 // Return value for any SBI ecall.
 struct sbi_ret {
 	long error;
@@ -37,6 +43,7 @@ extern struct sbi_ret __sbi_ecall(unsigned long arg0, unsigned long arg1, unsign
 								  unsigned long arg3, unsigned long arg4, unsigned long arg5,
 								  int fid, int ext);
 
+#define sbi_ecall1(ext, fid, arg0) __sbi_ecall(arg0, 0, 0, 0, 0, 0, fid, ext)
 #define sbi_ecall2(ext, fid, arg0, arg1) __sbi_ecall(arg0, arg1, 0, 0, 0, 0, fid, ext)
 
 #endif // __FBOS_SBI_H_
-- 
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