kernel: Add serial logging support

Signed-off-by: Ian Moffett <ian@osmora.org>

7 files changed, 181 insertions, 1 deletions

diff --git a/Makefile.in b/Makefile.in
index b00c05d..63120db 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -5,6 +5,7 @@
 # Feature stuff
 ###############################
 override SPECTRE_MITIGATION = @SPECTRE_MITIGATION@
+override SERIAL_DEBUG = @SERIAL_DEBUG@
 
 ifeq ($(SPECTRE_MITIGATION), 1)
 	override SPECTRE_FLAGS=-D__SPECTRE_MITIGATION
@@ -12,6 +13,12 @@ else
 	override SPECTRE_FLAGS=
 endif
 
+ifeq ($(SERIAL_DEBUG), 1)
+	override SERIAL_DEBUG_FLAGS=-D__SERIAL_DEBUG
+else
+	override SERIAL_DEBUG_FLAGS=
+endif
+
 
 ###############################
 # CFLAGS, QEMU flags + misc
@@ -23,7 +30,8 @@ override KERNEL_DEFINES =  -DHYRA_VERSION="\"$(HYRA_VERSION)\""\
 			   -DHYRA_BUILDDATE="\"@HYRA_BUILDDATE@\""\
 			   -DHYRA_BUILDBRANCH="\"@HYRA_BUILDBRANCH@\""\
 			   -DHYRA_ARCH="\"@ARCH@\""\
-			   $(SPECTRE_FLAGS)
+			   $(SPECTRE_FLAGS)\
+			   $(SERIAL_DEBUG_FLAGS)
 override KERNEL_CFLAGS = @KERNEL_CFLAGS@ $(KERNEL_DEFINES)
 override KERNEL_LDFLAGS = -nostdlib -zmax-page-size=0x1000 -static -Tconf/link-$(ARCH).ld
 override QEMU_FLAGS = @QEMU_FLAGS@
diff --git a/configure.ac b/configure.ac
index ffb2daf..afe3e34 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,6 +21,11 @@ AC_ARG_ENABLE([spectre-mitigation],
     [AS_HELP_STRING([--enable-spectre-mitigation], [Enable Spectre mitigation (IBRS or similar)])],,
     [enable_spectre_mitigation=$enableval])
 
+# Enable serial debug
+AC_ARG_ENABLE([serial-debug],
+    [AS_HELP_STRING([--enable-serial-debug], [Allow serial debugging])],,
+    [enable_serial_debug=$enableval])
+
 
 if test "x$enable_spectre_mitigation" = "xyes"; then
     AC_SUBST(SPECTRE_MITIGATION, [1])
@@ -28,6 +33,12 @@ else
     AC_SUBST(SPECTRE_MITIGATION, [0])
 fi
 
+if test "x$enable_serial_debug" = "xyes"; then
+    AC_SUBST(SERIAL_DEBUG, [1])
+else
+    AC_SUBST(SERIAL_DEBUG, [0])
+fi
+
 AC_SUBST(HYRA_BUILDDATE, [$HYRA_BUILDDATE])
 AC_SUBST(HYRA_BUILDBRANCH, [$HYRA_BUILDBRANCH])
 
diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index ec1d48f..f5b6365 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -37,6 +37,7 @@
 #include <machine/tss.h>
 #include <machine/spectre.h>
 #include <machine/cpu.h>
+#include <machine/uart.h>
 #include <firmware/acpi/acpi.h>
 
 __MODULE_NAME("machdep");
@@ -80,6 +81,16 @@ processor_halt(void)
     __ASMV("cli; hlt");
 }
 
+
+/*
+ * Send char to serial for debugging purposes.
+ */
+void
+serial_dbgch(char c)
+{
+    uart8250_write(c);
+}
+
 /*
  * Things set up before processor_init() call...
  */
@@ -90,6 +101,7 @@ pre_init(void)
      * These are critical things that need to be set up as soon as possible
      * way before the processor_init() call.
      */
+    uart8250_try_init();
     interrupts_init();
     gdt_load(&g_gdtr);
 }
diff --git a/sys/arch/amd64/amd64/uart.c b/sys/arch/amd64/amd64/uart.c
new file mode 100644
index 0000000..0bf0236
--- /dev/null
+++ b/sys/arch/amd64/amd64/uart.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <machine/uart.h>
+#include <machine/io.h>
+
+#define UART_COM1 0x3F8
+
+#define UART_PORTNO(OFFSET) (UART_COM1 + 1)
+
+static bool
+uart8250_transmit_empty(void)
+{
+    return __TEST(UART_PORTNO(5), __BIT(5));
+}
+
+void
+uart8250_write(char byte)
+{
+    while (!uart8250_transmit_empty());
+    outb(UART_COM1, byte);
+}
+
+int
+uart8250_try_init(void)
+{
+    /* Disable interrutps */
+    outb(UART_PORTNO(1), 0x00);
+
+    /* Enable DLAB to set divisor latches */
+    outb(UART_PORTNO(3), 0x80);
+
+    /* Set to 38400 baud via divisor latches (DLL and DLH)*/
+    outb(UART_PORTNO(0), 0x03);
+    outb(UART_PORTNO(1), 0x00);
+
+    /*
+     * Set Data Word Length to 8 bits...
+     *
+     * XXX: Our write does not preserve the DLAB bit...
+     *      We want to clear it to make the baud latches
+     *      readonly
+     */
+    outb(UART_PORTNO(3), 0x03);
+
+    /*
+     * We want FIFO to be enabled, and want to clear the
+     * TX/RX queues. We also want to set the interrupt
+     * watermark at 14 bytes.
+     */
+    outb(UART_PORTNO(2), 0xC7);
+
+    /*
+     * Enable auxiliary output 2 (used as interrupt line) and
+     * mark data terminal ready.
+     */
+    outb(UART_PORTNO(4), 0x0B);
+
+    /* Enable interrupts */
+    outb(UART_PORTNO(1), 0x01);
+
+    /* Put chip in loopback mode... test chip w/ test byte */
+    outb(UART_PORTNO(4), 0x1E);
+    outb(UART_PORTNO(0), 0xAE);
+    if (inb(UART_PORTNO(0) != 0xAE)) {
+        /* Not the same byte, something is wrong */
+        return 1;
+    }
+    return 0;
+}
diff --git a/sys/include/arch/amd64/uart.h b/sys/include/arch/amd64/uart.h
new file mode 100644
index 0000000..a49e626
--- /dev/null
+++ b/sys/include/arch/amd64/uart.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* UART 8250 init logic */
+
+#ifndef _UART_H_
+#define _UART_H_
+
+#include <sys/types.h>
+
+int uart8250_try_init(void);
+void uart8250_write(char byte);
+
+#endif
diff --git a/sys/include/sys/machdep.h b/sys/include/sys/machdep.h
index f494f73..5964369 100644
--- a/sys/include/sys/machdep.h
+++ b/sys/include/sys/machdep.h
@@ -38,6 +38,7 @@
 __weak void processor_init(void);
 __weak void pre_init(void);
 __weak void processor_halt(void);
+__weak void serial_dbgch(char c);
 
 #endif  /* defined(_KERNEL) */
 #endif  /* !_SYS_MACHDEP_H_ */
diff --git a/sys/kern/kern_syslog.c b/sys/kern/kern_syslog.c
index ebc5512..84943b3 100644
--- a/sys/kern/kern_syslog.c
+++ b/sys/kern/kern_syslog.c
@@ -29,6 +29,7 @@
 
 #include <sys/syslog.h>
 #include <sys/tty.h>
+#include <sys/machdep.h>
 #include <string.h>
 
 static struct tty syslog_tty;
@@ -39,6 +40,15 @@ static bool is_conlog_init = false;
 static void
 syslog_write(const char *s, size_t len)
 {
+#if defined(__SERIAL_DEBUG)
+    size_t tmp_len = len;
+    const char *tmp_s = s;
+
+    while (tmp_len--) {
+        serial_dbgch(*tmp_s++);
+    }
+#endif  /* defined(__SERIAL_DEBUG) */
+
     if (is_conlog_init) {
         tty_write(&syslog_tty, s, len);
     }