tty/serial: Migrate 8250_fsl to use has_sysrq

The SUPPORT_SYSRQ ifdeffery is not nice as:
- May create misunderstanding about sizeof(struct uart_port) between
  different objects
- Prevents moving functions from serial_core.h
- Reduces readability (well, it's ifdeffery - it's hard to follow)

In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added.
Initialise it in driver's probe and remove ifdeffery.

In contrast to 8250/8250_of, legacy_serial on powerpc does fill
(struct plat_serial8250_port). The reason is likely that it's done on
device_initcall(), not on probe. So, 8250_core is not yet probed.

Propagate value from platform_device on 8250 probe - in case powepc
legacy driver it's initialized on initcall, in case 8250_of it will be
initialized later on of_platform_serial_setup().

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-6-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

5 files changed, 8 insertions, 6 deletions

diff --git a/arch/powerpc/kernel/legacy_serial.c b/arch/powerpc/kernel/legacy_serial.c
index 7cea5978f21f..f061e06e9f51 100644
--- a/arch/powerpc/kernel/legacy_serial.c
+++ b/arch/powerpc/kernel/legacy_serial.c
@@ -479,8 +479,10 @@ static void __init fixup_port_irq(int index,
 	port->irq = virq;
 
 #ifdef CONFIG_SERIAL_8250_FSL
-	if (of_device_is_compatible(np, "fsl,ns16550"))
+	if (of_device_is_compatible(np, "fsl,ns16550")) {
 		port->handle_irq = fsl8250_handle_irq;
+		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
+	}
 #endif
 }
 
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index e682390ce0de..0894a22fd702 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -816,6 +816,7 @@ static int serial8250_probe(struct platform_device *dev)
 		uart.port.flags		= p->flags;
 		uart.port.mapbase	= p->mapbase;
 		uart.port.hub6		= p->hub6;
+		uart.port.has_sysrq	= p->has_sysrq;
 		uart.port.private_data	= p->private_data;
 		uart.port.type		= p->type;
 		uart.port.serial_in	= p->serial_in;
diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c
index aa0e216d5ead..0d0c80905c58 100644
--- a/drivers/tty/serial/8250/8250_fsl.c
+++ b/drivers/tty/serial/8250/8250_fsl.c
@@ -1,8 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#if defined(CONFIG_SERIAL_8250_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
-#define SUPPORT_SYSRQ
-#endif
-
 #include <linux/serial_reg.h>
 #include <linux/serial_8250.h>
 
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 92fbf46ce3bd..531ad67395e0 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -222,8 +222,10 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 
 	if (IS_ENABLED(CONFIG_SERIAL_8250_FSL) &&
 	    (of_device_is_compatible(np, "fsl,ns16550") ||
-	     of_device_is_compatible(np, "fsl,16550-FIFO64")))
+	     of_device_is_compatible(np, "fsl,16550-FIFO64"))) {
 		port->handle_irq = fsl8250_handle_irq;
+		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
+	}
 
 	return 0;
 err_unprepare:
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index bb2bc99388ca..6a8e8c48c882 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -25,6 +25,7 @@ struct plat_serial8250_port {
 	unsigned char	regshift;	/* register shift */
 	unsigned char	iotype;		/* UPIO_* */
 	unsigned char	hub6;
+	unsigned char	has_sysrq;	/* supports magic SysRq */
 	upf_t		flags;		/* UPF_* flags */
 	unsigned int	type;		/* If UPF_FIXED_TYPE */
 	unsigned int	(*serial_in)(struct uart_port *, int);