visionfive2 boots

+ Make 8250 serial driver more generic
+ Still TODO: write a tutorial on how to boot on the visionfive2

6 files changed, 138 insertions, 88 deletions

diff --git a/arch/riscv64/config.h b/arch/riscv64/config.h
index 3eb2e72..a2694d5 100644
--- a/arch/riscv64/config.h
+++ b/arch/riscv64/config.h
@@ -21,8 +21,7 @@
 #include <kmi/sizes.h>
 
 /* --- START ARCH USER CONFIG VALUES --- */
-/** Physical address to where the OS image will be loaded. */
-//#define RAM_BASE 0x80000000
+/* nada for now */
 /* --- END ARCH USER CONFIG VALUES --- */
 
 /* don't touch >:( */
diff --git a/arch/riscv64/kernel/vmem.c b/arch/riscv64/kernel/vmem.c
index f29c325..89d895f 100644
--- a/arch/riscv64/kernel/vmem.c
+++ b/arch/riscv64/kernel/vmem.c
@@ -369,7 +369,7 @@ void flush_tlb(uintptr_t addr)
 
 void flush_tlb_full()
 {
-	__asm__ volatile ("sfence.vma %0\n" :: "r" (0) : "memory");
+	__asm__ volatile ("sfence.vma %0\n" : : "r" (0) : "memory");
 }
 
 void flush_tlb_all()
@@ -451,9 +451,17 @@ stat_t populate_kvmem(struct vmem *b)
 vm_t setup_kernel_io(struct vmem *b, vm_t paddr)
 {
 	pm_t top_page = paddr / TOP_PAGE_SIZE;
-	b->leaf[IO_PAGE] = (struct vmem *)to_pte(top_page * TOP_PAGE_SIZE,
-	                                         VM_V | VM_R | VM_W | VM_A | VM_D);
-	return -TOP_PAGE_SIZE + paddr - (top_page * TOP_PAGE_SIZE);
+	pm_t addr = top_page * TOP_PAGE_SIZE;
+	b->leaf[IO_PAGE] = (struct vmem *)to_pte(addr,
+	                                         VM_V | VM_R | VM_W | VM_A |
+	                                         VM_D);
+	/* flush might be necessary when we're in the actual vmem we're
+	 * modifying, or during the startup stage where we don't have a tcb yet.
+	 * I don't think checking the rpc context is necessary? */
+	if (!cur_tcb() || cur_tcb()->proc.vmem == b)
+		flush_tlb((uintptr_t)pte_addr(b->leaf[IO_PAGE]));
+
+	return -TOP_PAGE_SIZE + paddr - addr;
 }
 #endif
 
diff --git a/common/debug.c b/common/debug.c
index 346934a..f3cacdf 100644
--- a/common/debug.c
+++ b/common/debug.c
@@ -20,18 +20,21 @@
 
 /** Debug context structure. */
 struct dbg_info {
-	/** Address of serial device in memory. */
-	pm_t dbg_ptr;
-
+	/** Address of serial device in virtual memory. Always access registers
+	 * through this address rather than \p addr. */
+	pm_t base;
+	/** Shift count between registers of serial device. */
+	size_t shift;
 	/** Type of serial device. */
 	enum serial_dev dev;
+	/** Physical address of serial device. */
+	pm_t addr;
 };
 
 /** Static debugging information. */
 static struct dbg_info dbg_info = (struct dbg_info){ 0 };
 
 /* forward declarations. */
-static void __setup_dbg(pm_t pt, enum serial_dev dev);
 static struct dbg_info __dbg_from_fdt(const void *fdt);
 
 void init_dbg(const void *fdt)
@@ -41,51 +44,41 @@ void init_dbg(const void *fdt)
 
 void setup_dmap_dbg()
 {
-	__setup_dbg(dbg_info.dbg_ptr, dbg_info.dev);
+	/* noop with the new 8250 driver, though might still be useful in the
+	 * future if I add in some other kind of simple uart */
 }
 
 void setup_io_dbg(struct vmem *b)
 {
-	vm_t io_ptr = map_io_dbg(b);
-	__setup_dbg(io_ptr, dbg_info.dev);
+	dbg_info.base = map_io_dbg(b);
 }
 
 vm_t map_io_dbg(struct vmem *b)
 {
-	return setup_kernel_io(b, dbg_info.dbg_ptr);
+	return setup_kernel_io(b, dbg_info.addr);
 }
 
+/** 8250 data register index. */
+#define UART_8250_DATA 0
+/** 8250 irq register idex. */
+#define UART_8250_IRQ 1
+/** 8250 ird_id register index. */
+#define UART_8250_IRQ_ID 2
+/** 8250 lcr register index. */
+#define UART_8250_LCR 3
+/** 8250 mcr register index. */
+#define UART_8250_MCR 4
+/** 8250 lsr register index. */
+#define UART_8250_LSR 5
+/** 8250 msr register index. */
+#define UART_8250_MSR 6
+/** 8250 scr register index. */
+#define UART_8250_SCR 7
+
 /* 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. */
 
-/** 8250 and compatible serial drivers. */
-struct __packed uart_8250 {
-	/** Receiver buffer/transmitter holding register. */
-	uint8_t data;
-
-	/** Interrupt enable register. */
-	uint8_t irq;
-
-	/** Interrupt identity/FIFO control register. */
-	uint8_t irq_id;
-
-	/** Line control register. */
-	uint8_t lcr;
-
-	/** Modem control register. */
-	uint8_t mcr;
-
-	/** Line status register. */
-	uint8_t lsr;
-
-	/** Modem status register. */
-	uint8_t msr;
-
-	/** Scratch register. */
-	uint8_t scr;
-};
-
 /** Line status data ready. */
 #define LSR_DR (1 << 0)
 
@@ -111,17 +104,11 @@ struct __packed uart_8250 {
 #define LSR_ERR (1 << 7)
 
 /**
- * Address of generic 8250 port. If other serial drivers are added, this should
- * maybe be made a void *. No support for quirks at the moment.
- */
-static struct uart_8250 *port = 0;
-
-/**
- * Serial transmitter empty.
+ * 8250 transmitter empty.
  *
  * @return \c 0 if not empty, non-zero otherwise.
  */
-static int __serial_tx_empty()
+static int __8250_tx_empty()
 {
 	/**
 	 * @todo visionfive2 loops on lsr indefinitely, why?
@@ -129,23 +116,43 @@ static int __serial_tx_empty()
 	 * meaning the registers are spaced apart more in memory than my naive
 	 * struct.
 	 * */
-	return port->lsr & LSR_THRE;
+	volatile uint8_t *lsr = (uint8_t *)dbg_info.base +
+	                        (UART_8250_LSR << dbg_info.shift);
+	return (*lsr) & LSR_THRE;
 }
 
 /**
- * Put character out onto serial lines.
+ * Put character out onto 8250 serial lines.
  *
  * @param c Character to output.
  */
-static void __putchar(char c)
+static void __8250_putchar(char c)
 {
-	if (!port)
+	if (!dbg_info.base)
 		return;
 
-	while (__serial_tx_empty() == 0)
+	while (__8250_tx_empty() == 0)
 		;
 
-	port->data = c;
+	volatile uint8_t *data = (uint8_t *)dbg_info.base +
+	                         (UART_8250_DATA << dbg_info.shift);
+	*data = c;
+}
+
+/**
+ * Put one character out on the serial lines.
+ * Automatically handles newlines.
+ *
+ * @param c Character to put.
+ */
+static void __putchar(char c)
+{
+	if (c == '\n')
+		__putchar('\r');
+
+	switch (dbg_info.dev) {
+	case UART_8250: __8250_putchar(c); return;
+	}
 }
 
 /**
@@ -200,28 +207,18 @@ static struct dbg_info __dbg_from_fdt(const void *fdt)
 	/* get serial device address */
 	struct cell_info ci = get_reginfo(fdt, stdout);
 	void *reg_ptr = (void *)fdt_getprop(fdt, stdout_offset, "reg", NULL);
-
 	pm_t dbg_ptr = (pm_t)fdt_load_int_ptr(ci.addr_cells, reg_ptr);
 
-	return (struct dbg_info){ dbg_ptr, dev };
-}
-
-/**
- * Set static port.
- *
- * @param pt Address of memory mapped serial device.
- * @param dev Chosen device.
- */
-void __setup_dbg(vm_t pt, enum serial_dev dev)
-{
-	switch (dev) {
-	case UART_8250:
-		port = (struct uart_8250 *)pt;
-		break;
-	}
+	/* get serial device offset if present */
+	size_t shift = 0;
+	void *shift_ptr = (void *)fdt_getprop(fdt, stdout_offset, "reg-shift",
+	                                      NULL);
+	if (shift_ptr)
+		shift = (size_t)fdt_load_int32_ptr(shift_ptr);
 
-	/* in the future possibly configure the serial connection, though the
-	 * defaults (set by U-boot) seem to work alright */
+	/* while in direct map, base == addr, and this changes only when we jump
+	 * into virtually mapped io */
+	return (struct dbg_info){ dbg_ptr, shift, dev, dbg_ptr };
 }
 
 /** Printf formatting left align flag. */
diff --git a/common/initrd.c b/common/initrd.c
index 4bb25e9..caff8b3 100644
--- a/common/initrd.c
+++ b/common/initrd.c
@@ -11,6 +11,7 @@
 #include <kmi/string.h>
 #include <kmi/utils.h>
 #include <kmi/attrs.h>
+#include <kmi/debug.h>
 #include <libfdt.h>
 
 /** GNU cpio, POSIX 'newc' format header. */
diff --git a/common/pmem.c b/common/pmem.c
index c817c5a..0fa647f 100644
--- a/common/pmem.c
+++ b/common/pmem.c
@@ -518,6 +518,11 @@ pm_t probe_pmap(size_t ram_size)
  */
 static void __mark_area_used(pm_t base, pm_t top)
 {
+	if (top < base) {
+		bug("top < base: %lx < %lx\n", top, base);
+		return;
+	}
+
 	size_t area_left = top - base;
 	pm_t runner = base;
 	while (area_left >= BASE_PAGE_SIZE) {
@@ -537,20 +542,29 @@ static void __mark_area_used(pm_t base, pm_t top)
  */
 static void __mark_reserved_mem(void *fdt)
 {
-	int rmem_offset = fdt_path_offset(fdt, "/reserved-memory/mmode_resv0");
-	struct cell_info ci = get_reginfo(fdt, "/reserved-memory/mmode_resv0");
-	uint8_t *rmem_reg =
-		(uint8_t *)fdt_getprop(fdt, rmem_offset, "reg", NULL);
+	int rmem_offset = fdt_path_offset(fdt, "/reserved-memory");
+	struct cell_info ci = get_reginfo(fdt, "/reserved-memory");
 
-	pm_t base = (pm_t)fdt_load_int_ptr(ci.addr_cells, rmem_reg);
+	int node = 0;
+	fdt_for_each_subnode(node, fdt, rmem_offset) {
+		uint8_t *rmem_reg =
+			(uint8_t *)fdt_getprop(fdt, node, "reg", NULL);
 
-	if (ci.addr_cells == 2)
-		rmem_reg += sizeof(fdt64_t);
-	else
-		rmem_reg += sizeof(fdt32_t);
+		pm_t base = (pm_t)fdt_load_int_ptr(ci.addr_cells, rmem_reg);
+
+		if (ci.addr_cells == 2)
+			rmem_reg += sizeof(fdt64_t);
+		else
+			rmem_reg += sizeof(fdt32_t);
 
-	pm_t top = (pm_t)fdt_load_int_ptr(ci.size_cells, rmem_reg) + base;
-	__mark_area_used((pm_t)__va(base), (pm_t)__va(top));
+		/** @todo make sure the top of a reserved memory area doesn't go
+		 * against our assumptions in FW_MAX_SIZE? */
+		pm_t top =
+			(pm_t)fdt_load_int_ptr(ci.size_cells, rmem_reg) + base;
+		__mark_area_used((pm_t)__va(base), (pm_t)__va(top));
+		info("marked [%lx - %lx] reserved\n", (pm_t)__va(
+			     base), (pm_t)__va(top));
+	}
 }
 
 /**
@@ -603,6 +617,13 @@ static pm_t __get_fdtbase(void *fdt)
 
 void init_pmem(void *fdt)
 {
+	/** @todo should I keep the info outputs? I suppose it's nice to see
+	 * if any assumption is being broken in the serial log, but in that case
+	 * I should really try adding more of them to other parts of the
+	 * codebase as well, the pmem subsystem isn't really especially complex.
+	 */
+	info("initializing pmem\n");
+
 	size_t max_order = 0;
 	size_t base_bits = 0;
 	size_t bits[NUM_ORDERS] = { 0 };
@@ -612,17 +633,29 @@ void init_pmem(void *fdt)
 	pm_t ram_size = __get_ramtop(fdt) - get_ram_base();
 	pm_t ram_base = (pm_t)__va(get_ram_base());
 
+	info("using ram range [%lx - %lx]\n",
+	     ram_base, ram_base + ram_size);
+
 	/** @todo could probably improve error messages on failing to get fdt
 	 * values */
+	pm_t initrd_base = get_initrdbase(fdt);
 	pm_t initrd_top = get_initrdtop(fdt);
+	info("found initrd at [%lx - %lx]\n", initrd_base, initrd_top);
+
 	pm_t fdt_top = __get_fdttop(fdt);
+	pm_t fdt_base = __get_fdtbase(fdt);
+	info("found fdt at [%lx - %lx]\n", fdt_base, fdt_top);
 
 	/* find probably most suitable contiguous region of ram for our physical
 	 * ram map */
 	pm_t pmap_base = align_up(MAX(initrd_top, fdt_top), sizeof(int));
+	info("choosing to place pmem map at %lx\n", pmap_base);
 
 	size_t probe_size = probe_pmap(ram_size);
+	info("pmem map probe size returned %lu\n", probe_size);
+
 	size_t actual_size = populate_pmap(ram_base, ram_size, pmap_base);
+	info("pmem map actual size %lu\n", actual_size);
 
 	if (probe_size != actual_size) {
 		bug("probe_size (%#lx) != actual_size (%#lx)\n", probe_size,
@@ -632,17 +665,25 @@ void init_pmem(void *fdt)
 	/* mark init stack, this should be unmapped once we get to executing
 	 * processes */
 	__mark_area_used(VM_STACK_BASE, VM_STACK_TOP);
+	info("marked stack [%lx - %lx] used\n", VM_STACK_BASE, VM_STACK_TOP);
 
 	/* mark kernel */
 	/* this could be made more explicit, I suppose. */
 	__mark_area_used(VM_KERN, VM_KERN + PM_KERN_SIZE);
+	info("marked kernel [%lx - %lx] used\n", VM_KERN,
+	     VM_KERN + PM_KERN_SIZE);
 
 	/* mark fdt and initrd */
-	__mark_area_used(get_initrdbase(fdt), initrd_top);
-	__mark_area_used(__get_fdtbase(fdt), fdt_top);
+	__mark_area_used(initrd_base, initrd_top);
+	info("marked initrd [%lx - %lx] used\n", initrd_base, initrd_top);
+
+	__mark_area_used(fdt_base, fdt_top);
+	info("marked fdt [%lx - %lx] used\n", fdt_base, fdt_top);
 
 	/* mark pmap */
 	__mark_area_used(pmap_base, pmap_base + actual_size);
+	info("marked pmap [%lx - %lx] used\n", pmap_base,
+	     pmap_base + actual_size);
 
 	/* mark reserved mem */
 	__mark_reserved_mem(fdt);
diff --git a/include/arch/vmem.h b/include/arch/vmem.h
index d2f031d..118e6ff 100644
--- a/include/arch/vmem.h
+++ b/include/arch/vmem.h
@@ -98,7 +98,11 @@ stat_t mod_vpage(struct vmem *branch, vm_t vaddr, pm_t paddr, vmflags_t flags);
 stat_t stat_vpage(struct vmem *branch, vm_t vaddr, pm_t *paddr,
                   enum mm_order *order, vmflags_t *flags);
 
-/** Flush tlb entry where associated with address \p addr. */
+/**
+ * Flush tlb entry where associated with address \p addr.
+ *
+ * @param addr Virtual address region to flush.
+ */
 void flush_tlb(uintptr_t addr);
 
 /** Flush full tlb of current address space. */