powerpc/legacy_serial: Use early_ioremap()

[    0.000000] ioremap() called early from find_legacy_serial_ports+0x3cc/0x474. Use early_ioremap() instead

find_legacy_serial_ports() is called early from setup_arch(), before
paging_init(). vmalloc is not available yet, ioremap shouldn't be
used that early.

Use early_ioremap() and switch to a regular ioremap() later.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/103ed8ee9e5973c958ec1da2d0b0764f69395d01.1618925560.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/legacy_serial.c

@@ -15,6 +15,7 @@
 #include <asm/udbg.h>
 #include <asm/pci-bridge.h>
 #include <asm/ppc-pci.h>
+#include <asm/early_ioremap.h>
 
 #undef DEBUG
 
@@ -34,6 +35,7 @@ static struct legacy_serial_info {
 	unsigned int			clock;
 	int				irq_check_parent;
 	phys_addr_t			taddr;
+	void __iomem			*early_addr;
 } legacy_serial_infos[MAX_LEGACY_SERIAL_PORTS];
 
 static const struct of_device_id legacy_serial_parents[] __initconst = {
@@ -325,17 +327,16 @@ static void __init setup_legacy_serial_console(int console)
 {
 	struct legacy_serial_info *info = &legacy_serial_infos[console];
 	struct plat_serial8250_port *port = &legacy_serial_ports[console];
-	void __iomem *addr;
 	unsigned int stride;
 
 	stride = 1 << port->regshift;
 
 	/* Check if a translated MMIO address has been found */
 	if (info->taddr) {
-		addr = ioremap(info->taddr, 0x1000);
-		if (addr == NULL)
+		info->early_addr = early_ioremap(info->taddr, 0x1000);
+		if (info->early_addr == NULL)
 			return;
-		udbg_uart_init_mmio(addr, stride);
+		udbg_uart_init_mmio(info->early_addr, stride);
 	} else {
 		/* Check if it's PIO and we support untranslated PIO */
 		if (port->iotype == UPIO_PORT && isa_io_special)
@@ -353,6 +354,30 @@ static void __init setup_legacy_serial_console(int console)
 	udbg_uart_setup(info->speed, info->clock);
 }
 
+static int __init ioremap_legacy_serial_console(void)
+{
+	struct legacy_serial_info *info = &legacy_serial_infos[legacy_serial_console];
+	struct plat_serial8250_port *port = &legacy_serial_ports[legacy_serial_console];
+	void __iomem *vaddr;
+
+	if (legacy_serial_console < 0)
+		return 0;
+
+	if (!info->early_addr)
+		return 0;
+
+	vaddr = ioremap(info->taddr, 0x1000);
+	if (WARN_ON(!vaddr))
+		return -ENOMEM;
+
+	udbg_uart_init_mmio(vaddr, 1 << port->regshift);
+	early_iounmap(info->early_addr, 0x1000);
+	info->early_addr = NULL;
+
+	return 0;
+}
+early_initcall(ioremap_legacy_serial_console);
+
 /*
  * This is called very early, as part of setup_system() or eventually
  * setup_arch(), basically before anything else in this file. This function