[PATCH 3/4] RISC-V: board-dt-2nd: add PBL console support for virt

[Ahmad Fatoum]

The Virt machine has a ns16550a UART at address 0x10000000. As we reuse
the generic DT image for this platform, we can't use either DEBUG_LL or
pbl_console as we would need to hardcode information on what UART is
available where, which wouldn't be correct for other boards.

However, if we parse the board compatible, we could match it with the
appropriate PBL console implementation without sacrificing portability.
Do so.

Signed-off-by: Ahmad Fatoum <ahmad at a3f.at>
---
 arch/riscv/boot/board-dt-2nd.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/boot/board-dt-2nd.c b/arch/riscv/boot/board-dt-2nd.c
index be28ea23cd6d..e9810f8add97 100644
--- a/arch/riscv/boot/board-dt-2nd.c
+++ b/arch/riscv/boot/board-dt-2nd.c
@@ -3,7 +3,7 @@
 #include <common.h>
 #include <asm/sections.h>
 #include <linux/sizes.h>
-#include <debug_ll.h>
+#include <asm/ns16550.h>
 #include <pbl.h>
 #include <fdt.h>
 
@@ -22,10 +22,29 @@
 
 #include <asm/barebox-riscv.h>
 
+static void virt_ns16550_putc(void *base, int ch)
+{
+	early_ns16550_putc(ch, base, 0, readb, writeb);
+}
+
+static void virt_ns16550_init(void)
+{
+	void __iomem *base = IOMEM(0x10000000);
+
+	early_ns16550_init(base, 3686400 / CONFIG_BAUDRATE, 0, writeb);
+	pbl_set_putc(virt_ns16550_putc, base);
+}
+
+static const struct fdt_device_id console_ids[] = {
+	{ .compatible = "riscv-virtio", .data = virt_ns16550_init },
+	{ /* sentinel */ }
+};
+
 ENTRY_FUNCTION(start_dt_2nd, a0, _fdt, a2)
 {
 	unsigned long membase, memsize, endmem, endfdt, uncompressed_len;
 	struct fdt_header *fdt = (void *)_fdt;
+	void (*pbl_uart_init)(void);
 
 	if (!fdt)
 		hang();
@@ -33,6 +52,12 @@ ENTRY_FUNCTION(start_dt_2nd, a0, _fdt, a2)
 	relocate_to_current_adr();
 	setup_c();
 
+	pbl_uart_init = fdt_device_get_match_data(fdt, "/", console_ids);
+	if (pbl_uart_init) {
+		pbl_uart_init();
+		putchar('>');
+	}
+
 	fdt_find_mem(fdt, &membase, &memsize);
 	endmem = membase + memsize;
 	endfdt = _fdt + be32_to_cpu(fdt->totalsize);
-- 
2.30.0