From 317da94139c592d20e90a4f74cdb67c620d72d4a Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sun, 19 May 2024 20:59:38 +0200
Subject: kernel: implement /dev/bintime

---
 src/kernel/arch/amd64/boot.c          |  1 +
 src/kernel/arch/amd64/driver/driver.h |  1 +
 src/kernel/arch/amd64/driver/time.c   | 80 +++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+)
 create mode 100644 src/kernel/arch/amd64/driver/time.c

(limited to 'src/kernel')

diff --git a/src/kernel/arch/amd64/boot.c b/src/kernel/arch/amd64/boot.c
index 19f249a..14690a8 100644
--- a/src/kernel/arch/amd64/boot.c
+++ b/src/kernel/arch/amd64/boot.c
@@ -70,6 +70,7 @@ void kmain_early(void *mbi) {
 	serial_init();
 	video_init(vid);
 	pata_init();
+	time_init();
 
 	{
 		struct multiboot_tag_old_acpi *mod;
diff --git a/src/kernel/arch/amd64/driver/driver.h b/src/kernel/arch/amd64/driver/driver.h
index 0c4ecd5..6f862cf 100644
--- a/src/kernel/arch/amd64/driver/driver.h
+++ b/src/kernel/arch/amd64/driver/driver.h
@@ -14,5 +14,6 @@ struct GfxInfo {
 void pata_init(void);
 void ps2_init(void);
 void rtl8139_init(uint32_t bdf);
+void time_init(void);
 void vfs_root_init(void);
 void video_init(GfxInfo);
diff --git a/src/kernel/arch/amd64/driver/time.c b/src/kernel/arch/amd64/driver/time.c
new file mode 100644
index 0000000..8ae6fb2
--- /dev/null
+++ b/src/kernel/arch/amd64/driver/time.c
@@ -0,0 +1,80 @@
+/* This is already sort of deprecated as I introduce it --
+ * it doesn't seem to provide much benefit over _sys_time, which I think I
+ * have to keep anyways, so processes in an empty namespace can still keep
+ * time. */
+#include <camellia/errno.h>
+#include <camellia/fsutil.h>
+#include <kernel/arch/amd64/driver/driver.h>
+#include <kernel/arch/amd64/driver/util.h>
+#include <kernel/malloc.h>
+#include <kernel/panic.h>
+#include <kernel/proc.h>
+#include <kernel/util.h>
+#include <kernel/vfs/mount.h>
+#include <kernel/vfs/request.h>
+#include <shared/mem.h>
+
+typedef struct {
+	uint64_t base;
+} TimeObj;
+
+static long
+handle(VfsReq *req)
+{
+	TimeObj *h;
+	if (req->type == VFSOP_OPEN) {
+		if (reqpathcmp(req, "")) {
+			h = kmalloc(sizeof *h, "dev/time");
+			h->base = uptime_ns();
+			return (uintptr_t)h;
+		} else {
+			return -ENOENT;
+		}
+	}
+	h = (__force void*)req->id;
+
+	if (req->type == VFSOP_CLOSE) {
+		assert(h);
+		kfree(h);
+		return 0;
+	}
+
+	uint64_t now = uptime_ns();
+
+	union {
+		char buf[8];
+		uint64_t t;
+	} u;
+	switch (req->type) {
+	case VFSOP_READ:
+		u.t = now - h->base;
+		return req_readcopy(req, u.buf, sizeof u.buf);
+	case VFSOP_GETSIZE:
+		return 8;
+	case VFSOP_WRITE:
+		if (req->input.len == 8) {
+			assert(!req->input.kern);
+			if (pcpy_from(req->caller, u.buf, req->input.buf, sizeof u.buf) != sizeof(u.buf)) {
+				return -EGENERIC;
+			}
+			h->base = now - u.t;
+			assert(u.t == now - h->base);
+			return 8;
+		}
+		return -EGENERIC;
+	default:
+		return -ENOSYS;
+	}
+}
+
+static void
+accept(VfsReq *req)
+{
+	vfsreq_finish_short(req, handle(req));
+}
+
+void
+time_init(void)
+{
+	vfs_root_register("/dev/bintime", accept);
+}
-- 
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