drivers/char: rename arm-uart.c to uart-init.c

Rename the file containing uart_init() to enable reuse across other
architectures that utilize device trees or SPCR tables to locate UART
information.
After locating UART data, {acpi}_device_init() is called to initialize
the UART.

arm_uart_init() is renamed to uart_init() to be reused by other
architectures.

A new configuration option, CONFIG_GENERIC_UART_INIT, is introduced,
currently available only for Arm. Enabling CONFIG_UART_INIT on additional
architectures will require additional functionality, such as device tree
mapping and unflattening, etc.

arm-uart.c is removed from "ARM (W/ VIRTUALIZATION EXTENSIONS) ARCHITECTURE"
section in the MAINTAINERS file, as it is no longer Arm-specific and can
now be maintained by maintainers of other architectures.

Use GENERIC_UART_INIT for CONFIG_ARM by adding `select GENERIC_UART_INIT`
to CONFIG_ARM.

Signed-off-by: Oleksii Kurochko <[email protected]>
Reviewed-by: Michal Orzel <[email protected]>
Acked-by: Julien Grall <[email protected]>

MAINTAINERS

@@ -245,7 +245,6 @@ S:	Supported
 L:	[email protected]
 F:	docs/misc/arm/
 F:	xen/arch/arm/
-F:	xen/drivers/char/arm-uart.c
 F:	xen/drivers/char/cadence-uart.c
 F:	xen/drivers/char/exynos4210-uart.c
 F:	xen/drivers/char/imx-lpuart.c

xen/arch/arm/Kconfig

@@ -12,6 +12,7 @@ config ARM_64
 config ARM
 	def_bool y
 	select FUNCTION_ALIGNMENT_4B
+	select GENERIC_UART_INIT
 	select HAS_ALTERNATIVE if HAS_VMAP
 	select HAS_DEVICE_TREE
 	select HAS_PASSTHROUGH

xen/arch/arm/setup.c

@@ -361,7 +361,7 @@ void asmlinkage __init start_xen(unsigned long fdt_paddr)
 
     gic_preinit();
 
-    arm_uart_init();
+    uart_init();
     console_init_preirq();
     console_init_ring();
 

xen/drivers/char/Kconfig

@@ -1,3 +1,6 @@
+config GENERIC_UART_INIT
+	bool
+
 config HAS_NS16550
 	bool "NS16550 UART driver" if ARM
 	default n if RISCV

xen/drivers/char/Makefile

@@ -11,7 +11,7 @@ obj-$(CONFIG_HAS_EHCI) += ehci-dbgp.o
 obj-$(CONFIG_XHCI) += xhci-dbc.o
 obj-$(CONFIG_HAS_IMX_LPUART) += imx-lpuart.o
 obj-$(CONFIG_HAS_LINFLEX) += linflex-uart.o
-obj-$(CONFIG_ARM) += arm-uart.o
+obj-$(CONFIG_GENERIC_UART_INIT) += uart-init.o
 obj-y += serial.o
 obj-$(CONFIG_XEN_GUEST) += xen_pv_console.o
 obj-$(CONFIG_PV_SHIM) += consoled.o

xen/drivers/char/arm-uart.c → xen/drivers/char/uart-init.c

@@ -1,20 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
 /*
+ * Derived from:
  * xen/drivers/char/arm-uart.c
  *
  * Generic uart retrieved via the device tree or ACPI
  *
  * Julien Grall <[email protected]>
  * Copyright (c) 2013 Linaro Limited.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
  */
 
 #include <asm/device.h>
@@ -126,7 +119,7 @@ static void __init acpi_uart_init(void)
 static void __init acpi_uart_init(void) { }
 #endif
 
-void __init arm_uart_init(void)
+void __init uart_init(void)
 {
     if ( acpi_disabled )
         dt_uart_init();

xen/include/xen/serial.h

@@ -166,7 +166,7 @@ void xhci_dbc_uart_init(void);
 static void inline xhci_dbc_uart_init(void) {}
 #endif
 
-void arm_uart_init(void);
+void uart_init(void);
 
 struct physdev_dbgp_op;
 int dbgp_op(const struct physdev_dbgp_op *op);