Added debug flags and simple debug serial driver

6 files changed, 198 insertions, 18 deletions

diff --git a/Makefile b/Makefile
index 5097ff0..187c269 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 DO		!= echo > deps.mk
 
-CFLAGS		= -fno-pie -ggdb3 -ffreestanding -nostdlib -std=c11 -Wall -Wextra -mcmodel=medany
+DEBUGFLAGS	!= [ $(DEBUG) ] && echo "-g3 -DDEBUG" || echo "-O2"
+CFLAGS		= -fno-pie -ffreestanding -nostdlib -std=c11 -Wall -Wextra
 DEPFLAGS	= -MT $@ -MMD -MP -MF $@.d
 
 all: apos.bin
@@ -26,8 +27,8 @@ include arch/$(ARCH)/source.mk
 INCLUDE_FLAGS	:= -I include -I arch/$(ARCH)/include\
 	-include config.h -include arch/$(ARCH)/config.h
 
-COMPILE		= $(CROSS_COMPILE)$(CC) $(CFLAGS) $(DEPFLAGS) $(INCLUDE_FLAGS)
-GENELF		= $(CROSS_COMPILE)$(CC) $(CFLAGS) $(INCLUDE_FLAGS)
+COMPILE		= $(CROSS_COMPILE)$(CC) $(DEBUGFLAGS) $(CFLAGS) $(ARCH_FLAGS) $(DEPFLAGS) $(INCLUDE_FLAGS)
+GENELF		= $(CROSS_COMPILE)$(CC) $(DEBUGFLAGS) $(CFLAGS) $(ARCH_FLAGS) $(INCLUDE_FLAGS)
 GENLINK		= $(CROSS_COMPILE)$(CPP) $(DEPFLAGS) $(INCLUDE_FLAGS)
 STRIPLINK	= sed -n '/^[^\#]/p'
 
diff --git a/arch/riscv/init/init.c b/arch/riscv/init/init.c
index bb16876..6bb6bc3 100644
--- a/arch/riscv/init/init.c
+++ b/arch/riscv/init/init.c
@@ -1,6 +1,8 @@
 #include <apos/init.h>
 #include <apos/sizes.h>
 #include <apos/types.h>
+#include <apos/string.h>
+#include <apos/debug.h>
 #include <libfdt.h>
 #include <pages.h>
 #include <csr.h>
@@ -11,40 +13,116 @@ struct mem_layout {
 	pm_t top;
 };
 
-struct mem_layout get_memlayout(void *fdt)
+struct cell_info {
+	uint32_t size_cells;
+	uint32_t addr_cells;
+};
+
+struct cell_info get_cellinfo(void *fdt, int offset)
 {
-	fdt32_t *size_ptr = (fdt32_t *)fdt_getprop(fdt, 0, "#size-cells", NULL);
-	fdt32_t *addr_ptr = (fdt32_t *)fdt_getprop(fdt, 0, "#address-cells", NULL);
 
-	uint32_t size_cells = fdt32_to_cpu(*size_ptr);
-	uint32_t addr_cells = fdt32_to_cpu(*addr_ptr);
+	fdt32_t *size_ptr = 0;
+	fdt32_t *addr_ptr = 0;
+
+	while (offset) {
+		size_ptr = (fdt32_t *) fdt_getprop(fdt, offset,
+				"#size-cells", NULL);
+
+		addr_ptr = (fdt32_t *) fdt_getprop(fdt, offset,
+				"#address-cells", NULL);
+
+		if (size_ptr && addr_ptr)
+			break;
+
+		/* dtc warns that this function is slow, but I don't care */
+		offset = fdt_parent_offset(fdt, offset);
+	}
+
+	struct cell_info ret = {0};
+
+	if (size_ptr && addr_ptr){
+		ret.size_cells = fdt32_to_cpu(*size_ptr);
+		ret.addr_cells = fdt32_to_cpu(*addr_ptr);
+	}
+
+	return ret;
+}
+
+struct mem_layout get_memlayout(void *fdt)
+{
+	struct cell_info ci = get_cellinfo(fdt, 0);
 
 	int mem_offset = fdt_path_offset(fdt, "/memory");
-	uint8_t *mem_reg = (uint8_t *)fdt_getprop(fdt, mem_offset, "reg", NULL);
+	uint8_t *mem_reg =
+		(uint8_t *) fdt_getprop(fdt, mem_offset, "reg", NULL);
 
 	pm_t base;
 	/* if riscv128 comes around we will probably see addr_cells == 4, but
 	 * I'm not too concerned about it at the moment */
-	if (addr_cells == 2) {
-		base = fdt64_to_cpu(*(fdt64_t *)mem_reg);
+	if (ci.addr_cells == 2) {
+		base = fdt64_to_cpu(*(fdt64_t *) mem_reg);
 		mem_reg += sizeof(fdt64_t);
 	} else {
-		base = fdt32_to_cpu(*(fdt32_t *)mem_reg);
+		base = fdt32_to_cpu(*(fdt32_t *) mem_reg);
 		mem_reg += sizeof(fdt32_t);
 	}
 
 	pm_t top;
-	if (size_cells == 2)
-		top = fdt64_to_cpu(*(fdt64_t *)mem_reg) + base;
+	if (ci.size_cells == 2)
+		top = fdt64_to_cpu(*(fdt64_t *) mem_reg) + base;
 	else
-		top = fdt32_to_cpu(*(fdt64_t *)mem_reg) + base;
+		top = fdt32_to_cpu(*(fdt64_t *) mem_reg) + base;
 
-	struct mem_layout ret = {base, top};
+	struct mem_layout ret = { base, top };
 	return ret;
 }
 
+#ifdef DEBUG
+
+/* this should probably be improved in the future, possibly also moved
+ * somewhere? */
+enum serial_dev_t serial_dev_enum(const char *dev_name)
+{
+	if (strncmp("ns16550", dev_name, 7) == 0)
+		return NS16550A;
+
+	return -1;
+}
+
+void init_debug(void *fdt)
+{
+	int offset = fdt_path_offset(fdt, "/soc/uart");
+
+	/* get serial device type */
+	const char *dev_name = (const char *)fdt_getprop(fdt, offset,
+			"compatible", NULL);
+
+	enum serial_dev_t dev = serial_dev_enum(dev_name);
+
+	/* get serial device address */
+	struct cell_info ci = get_cellinfo(fdt, offset);
+	void *reg_ptr = (void *)fdt_getprop(fdt, offset, "reg", NULL);
+
+	void *uart_ptr = 0;
+	if (ci.addr_cells == 2)
+		uart_ptr = (void *)(pm_t)fdt64_to_cpu(*(fdt64_t *) reg_ptr);
+	else
+		uart_ptr = (void *)(pm_t)fdt32_to_cpu(*(fdt32_t *) reg_ptr);
+
+	dbg_init(uart_ptr, dev);
+}
+
+#else
+
+#define init_debug(...)
+
+#endif
+
 void init(void *fdt)
 {
+	init_debug(fdt);
+	dbg("hello\n");
+
 	struct mem_layout pmem = get_memlayout(fdt);
 	/* struct mm_ptinfo ptbl = create_pagetable(pmem); */
 }
diff --git a/arch/riscv/source.mk b/arch/riscv/source.mk
index cf8edd7..50e0f5f 100644
--- a/arch/riscv/source.mk
+++ b/arch/riscv/source.mk
@@ -7,7 +7,7 @@ INIT_SOURCES	+= $(INIT_LOCAL) $(INIT_FDT)
 
 CLEANUP_CMD	:= ./arch/riscv/conf/rmimage.sh
 
-USE_FDT		:= y
+ARCH_FLAGS	:= -mcmodel=medany
 
 run:
 	./arch/riscv/conf/mkimage.sh
diff --git a/common/debug.c b/common/debug.c
new file mode 100644
index 0000000..be71cd2
--- /dev/null
+++ b/common/debug.c
@@ -0,0 +1,77 @@
+#include <apos/types.h>
+#include <apos/debug.h>
+
+#ifdef DEBUG
+
+/* if there arises a need for more supported serial drivers, I should probably
+ * try to implement some kind of basic driver subsystem, but this is good enough
+ * for now. */
+
+struct __packed ns16550a {
+	union {
+		struct {
+			uint8_t data;
+			uint8_t irq;
+		};
+
+		struct {
+			uint8_t lsbr;
+			uint8_t msbr;
+		};
+	};
+
+	uint8_t irq_id;
+	uint8_t lcr;
+	uint8_t mcr;
+	uint8_t lsr;
+	uint8_t msr;
+	uint8_t scr;
+};
+
+#define LSR_DR   (1 << 0)
+#define LSR_OE   (1 << 1)
+#define LSR_PE   (1 << 2)
+#define LSR_FE   (1 << 3)
+#define LSR_BI   (1 << 4)
+#define LSR_THRE (1 << 5)
+#define LSR_TEMT (1 << 6)
+#define LSR_ERR  (1 << 7)
+
+static struct ns16550a *port = 0;
+
+int __serial_tx_empty()
+{
+	return port->lsr & LSR_THRE;
+}
+
+void __serial_putchar(char c)
+{
+	if (!port)
+		return;
+
+	while(__serial_tx_empty() == 0);
+
+	port->data = c;
+}
+
+void dbg_init(void *pt, enum serial_dev_t dev)
+{
+	switch (dev) {
+		case NS16550A:
+			port = pt;
+			break;
+	}
+
+	/* in the future possibly configure the serial connection, though the
+	 * defaults (set by U-boot) seem to work alright */
+}
+
+void dbg(const char *fmt, ...)
+{
+	/* do a proper implementation later, for now just dump stuff */
+	while(*fmt){
+		__serial_putchar(*fmt++);
+	}
+}
+
+#endif /* DEBUG */
diff --git a/include/apos/attrs.h b/include/apos/attrs.h
index 00dcf82..e088ec9 100644
--- a/include/apos/attrs.h
+++ b/include/apos/attrs.h
@@ -1,7 +1,9 @@
 #ifndef APOS_COMPILER_ATTRIBUTES_H
 
 #define __section(section)	__attribute__((__section__(section)))
+#define __fmt(x, y)		__attribute__((format (__printf__, x, y)))
 #define __noinline		__attribute__((noinline))
-#define __weak			__attribute((weak))
+#define __weak			__attribute__((weak))
+#define __packed		__attribute__((packed))
 
 #endif /* APOS_COMPILER_ATTRIBUTES_H */
diff --git a/include/apos/debug.h b/include/apos/debug.h
new file mode 100644
index 0000000..021612d
--- /dev/null
+++ b/include/apos/debug.h
@@ -0,0 +1,22 @@
+#ifndef APOS_DEBUG_H
+#define APOS_DEBUG_H
+
+#include <apos/attrs.h>
+
+#ifdef DEBUG
+enum serial_dev_t {
+	/* only the NS16550A and compatible at the moment */
+	NS16550A,
+};
+
+void __fmt(1, 2) dbg(const char *fmt, ...);
+void dbg_init(void *pt, enum serial_dev_t dev);
+
+#else
+
+#define dbg(...)
+#define dbg_init(...)
+
+#endif /* DEBUG */
+
+#endif /* APOS_DEBUG_H */