[PATCH 4/5] serial: convert early_uart to earlycon for 8250

From: Yinghai Lu
Date: Thu May 31 2007 - 17:05:07 EST

Andrew,

Please don't drop others if there is problem with this one.

YH

[PATCH 4/5] serial: convert early_uart to earlycon for 8250

Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and
include/asm-x86_64/serial.h. the serial8250_ports need to be probed late
in serial initializing stage. the console_init=>serial8250_console_init=>
register_console=>serial8250_console_setup will return -ENDEV, and console
ttyS0 can not be enabled at that time.
need to wait till uart_add_one_port in drivers/serial/serial_core.c to call
register_console to get console ttyS0. that is too late.

Make early_uart to use early_param, so uart console can be used earlier.
Make it to be bootconsole with CON_BOOT flag, so can use console handover
feature. and it will switch to corresponding normal serial console
automatically.

new command line will be:
console=uart8250,io,0x3f8,9600n8
console=uart8250,mmio,0xff5e0000,115200n8
or
earlycon=uart8250,io,0x3f8,9600n8
earlycon=uart8250,mmio,0xff5e0000,115200n8

it will print in very early stage:
Early serial console at I/O port 0x3f8 (options '9600n8')
console [uart0] enabled
later for console it will print:
console handover: boot [uart0] -> real [ttyS0]

Signed-off-by: <yinghai.lu@xxxxxxx>

Documentation/kernel-parameters.txt | 11 +++
arch/ia64/kernel/setup.c | 4 -
drivers/serial/8250.c | 28 ++-------
drivers/serial/8250_early.c | 108 ++++++++++++++++--------------------
drivers/serial/Kconfig | 14 ++++
include/asm-i386/fixmap.h | 2
include/asm-i386/io.h | 1
include/asm-x86_64/fixmap.h | 4 +
include/asm-x86_64/io.h | 1
include/linux/console.h | 2
include/linux/serial.h | 6 --
include/linux/serial_8250.h | 3 +
init/main.c | 5 +
kernel/printk.c | 22 +++++++
14 files changed, 118 insertions(+), 93 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ce91560..4a9e271 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -464,13 +464,20 @@ and is between 256 and 4096 characters. It is defined in the file
Documentation/networking/netconsole.txt for an
alternative.

- uart,io,<addr>[,options]
- uart,mmio,<addr>[,options]
+ uart8250,io,<addr>[,options]
+ uart8250,mmio,<addr>[,options]
Start an early, polled-mode console on the 8250/16550
UART at the specified I/O port or MMIO address,
switching to the matching ttyS device later. The
options are the same as for ttyS, above.

+ earlycon= [KNL] Output early console device and options.
+ uart8250,io,<addr>[,options]
+ uart8250,mmio,<addr>[,options]
+ Start an early, polled-mode console on the 8250/16550
+ UART at the specified I/O port or MMIO address.
+ The options are the same as for ttyS, above.
+
cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
diff --git a/arch/i386/mm/ioremap.c b/arch/i386/mm/ioremap.c
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index eaa6a24..dd7f95b 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -390,10 +390,6 @@ early_console_setup (char *cmdline)
if (!efi_setup_pcdp_console(cmdline))
earlycons++;
#endif
-#ifdef CONFIG_SERIAL_8250_CONSOLE
- if (!early_serial_console_init(cmdline))
- earlycons++;
-#endif

return (earlycons) ? 0 : -1;
}
diff --git a/arch/x86_64/mm/ioremap.c b/arch/x86_64/mm/ioremap.c
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index c84dab0..0b3ec38 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2514,12 +2514,18 @@ static int __init serial8250_console_setup(struct console *co, char *options)
return uart_set_options(port, co, baud, parity, bits, flow);
}

+static int __init serial8250_console_early_setup(void)
+{
+ return serial8250_find_port_for_earlycon();
+}
+
static struct uart_driver serial8250_reg;
static struct console serial8250_console = {
.name = "ttyS",
.write = serial8250_console_write,
.device = uart_console_device,
.setup = serial8250_console_setup,
+ .early_setup = serial8250_console_early_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &serial8250_reg,
@@ -2533,7 +2539,7 @@ static int __init serial8250_console_init(void)
}
console_initcall(serial8250_console_init);

-static int __init find_port(struct uart_port *p)
+int serial8250_find_port(struct uart_port *p)
{
int line;
struct uart_port *port;
@@ -2546,26 +2552,6 @@ static int __init find_port(struct uart_port *p)
return -ENODEV;
}

-int __init serial8250_start_console(struct uart_port *port, char *options)
-{
- int line;
-
- line = find_port(port);
- if (line < 0)
- return -ENODEV;
-
- add_preferred_console("ttyS", line, options);
- printk("Adding console on ttyS%d at %s 0x%lx (options '%s')\n",
- line, port->iotype == UPIO_MEM ? "MMIO" : "I/O port",
- port->iotype == UPIO_MEM ? (unsigned long) port->mapbase :
- (unsigned long) port->iobase, options);
- if (!(serial8250_console.flags & CON_ENABLED)) {
- serial8250_console.flags &= ~CON_PRINTBUFFER;
- register_console(&serial8250_console);
- }
- return line;
-}
-
#define SERIAL8250_CONSOLE &serial8250_console
#else
#define SERIAL8250_CONSOLE NULL
diff --git a/drivers/serial/8250_early.c b/drivers/serial/8250_early.c
index 7e51119..58527c6 100644
--- a/drivers/serial/8250_early.c
+++ b/drivers/serial/8250_early.c
@@ -17,13 +17,11 @@
* we locate the device directly by its MMIO or I/O port address.
*
* The user can specify the device directly, e.g.,
- * console=uart,io,0x3f8,9600n8
- * console=uart,mmio,0xff5e0000,115200n8
- * or platform code can call early_uart_console_init() to set
- * the early UART device.
- *
- * After the normal serial driver starts, we try to locate the
- * matching ttyS device and start a console there.
+ * earlycon=uart8250,io,0x3f8,9600n8
+ * earlycon=uart8250,mmio,0xff5e0000,115200n8
+ * or
+ * console=uart8250,io,0x3f8,9600n8
+ * console=uart8250,mmio,0xff5e0000,115200n8
*/

#include <linux/tty.h>
@@ -32,17 +30,21 @@
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/serial.h>
+#include <linux/serial_8250.h>
#include <asm/io.h>
#include <asm/serial.h>
+#ifdef CONFIG_FIX_EARLYCON_MEM
+#include <asm/pgtable.h>
+#include <asm/fixmap.h>
+#endif

-struct early_uart_device {
+struct early_serial8250_device {
struct uart_port port;
char options[16]; /* e.g., 115200n8 */
unsigned int baud;
};

-static struct early_uart_device early_device __initdata;
-static int early_uart_registered __initdata;
+static struct early_serial8250_device early_device;

static unsigned int __init serial_in(struct uart_port *port, int offset)
{
@@ -80,7 +82,7 @@ static void __init putc(struct uart_port *port, int c)
serial_out(port, UART_TX, c);
}

-static void __init early_uart_write(struct console *console, const char *s, unsigned int count)
+static void __init early_serial8250_write(struct console *console, const char *s, unsigned int count)
{
struct uart_port *port = &early_device.port;
unsigned int ier;
@@ -111,7 +113,7 @@ static unsigned int __init probe_baud(struct uart_port *port)
return (port->uartclk / 16) / quot;
}

-static void __init init_port(struct early_uart_device *device)
+static void __init init_port(struct early_serial8250_device *device)
{
struct uart_port *port = &device->port;
unsigned int divisor;
@@ -130,10 +132,9 @@ static void __init init_port(struct early_uart_device *device)
serial_out(port, UART_LCR, c & ~UART_LCR_DLAB);
}

-static int __init parse_options(struct early_uart_device *device, char *options)
+static int __init parse_options(struct early_serial8250_device *device, char *options)
{
struct uart_port *port = &device->port;
- int mapsize = 64;
int mmio, length;

if (!options)
@@ -143,12 +144,18 @@ static int __init parse_options(struct early_uart_device *device, char *options)
if (!strncmp(options, "mmio,", 5)) {
port->iotype = UPIO_MEM;
port->mapbase = simple_strtoul(options + 5, &options, 0);
- port->membase = ioremap(port->mapbase, mapsize);
+#ifdef CONFIG_FIX_EARLYCON_MEM
+ set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, port->mapbase & PAGE_MASK);
+ port->membase = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
+ port->membase += port->mapbase & ~PAGE_MASK;
+#else
+ port->membase = ioremap(port->mapbase, 64);
if (!port->membase) {
printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
__FUNCTION__, port->mapbase);
return -ENOMEM;
}
+#endif
mmio = 1;
} else if (!strncmp(options, "io,", 3)) {
port->iotype = UPIO_PORT;
@@ -175,9 +182,16 @@ static int __init parse_options(struct early_uart_device *device, char *options)
return 0;
}

-static int __init early_uart_setup(struct console *console, char *options)
+static struct console early_serial8250_console __initdata = {
+ .name = "uart",
+ .write = early_serial8250_write,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
+ .index = -1,
+};
+
+static int __init early_serial8250_setup(char *options)
{
- struct early_uart_device *device = &early_device;
+ struct early_serial8250_device *device = &early_device;
int err;

if (device->port.membase || device->port.iobase)
@@ -190,61 +204,39 @@ static int __init early_uart_setup(struct console *console, char *options)
return 0;
}

-static struct console early_uart_console __initdata = {
- .name = "uart",
- .write = early_uart_write,
- .setup = early_uart_setup,
- .flags = CON_PRINTBUFFER,
- .index = -1,
-};
-
-static int __init early_uart_console_init(void)
-{
- if (!early_uart_registered) {
- register_console(&early_uart_console);
- early_uart_registered = 1;
- }
- return 0;
-}
-console_initcall(early_uart_console_init);
-
-int __init early_serial_console_init(char *cmdline)
+static int __init setup_early_serial8250_console(char *cmdline)
{
char *options;
int err;

- options = strstr(cmdline, "console=uart,");
+ options = strstr(cmdline, "uart8250,");
if (!options)
- return -ENODEV;
+ return 0;

options = strchr(cmdline, ',') + 1;
- if ((err = early_uart_setup(NULL, options)) < 0)
+ if ((err = early_serial8250_setup(options)) < 0)
return err;
- return early_uart_console_init();
+
+ register_console(&early_serial8250_console);
+
+ return 0;
}

-static int __init early_uart_console_switch(void)
+int __init serial8250_find_port_for_earlycon(void)
{
- struct early_uart_device *device = &early_device;
+ struct early_serial8250_device *device = &early_device;
struct uart_port *port = &device->port;
- int mmio, line;
+ int line;

- if (!(early_uart_console.flags & CON_ENABLED))
- return 0;
+ if (!device->port.membase && !device->port.iobase)
+ return -ENODEV;

- /* Try to start the normal driver on a matching line. */
- mmio = (port->iotype == UPIO_MEM);
- line = serial8250_start_console(port, device->options);
+ line = serial8250_find_port(port);
if (line < 0)
- printk("No ttyS device at %s 0x%lx for console\n",
- mmio ? "MMIO" : "I/O port",
- mmio ? port->mapbase :
- (unsigned long) port->iobase);
-
- unregister_console(&early_uart_console);
- if (mmio)
- iounmap(port->membase);
+ return -ENODEV;

- return 0;
+ return update_console_cmdline("uart", 8250,
+ "ttyS", line, device->options);
}
-late_initcall(early_uart_console_switch);
+
+early_param("earlycon", setup_early_serial8250_console);
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 315ea99..9cd751e 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -62,8 +62,22 @@ config SERIAL_8250_CONSOLE
kernel will automatically use the first serial line, /dev/ttyS0, as
system console.

+ you can set that using a kernel command line option such as
+ "console=uart8250,io,0x3f8,9600n8"
+ "console=uart8250,mmio,0xff5e0000,115200n8".
+ and it will switch to normal serial console when correponding port is
+ ready.
+ "earlycon=uart8250,io,0x3f8,9600n8"
+ "earlycon=uart8250,mmio,0xff5e0000,115200n8".
+ it will not only setup early console.
+
If unsure, say N.

+config FIX_EARLYCON_MEM
+ bool
+ depends on X86
+ default y
+
config SERIAL_8250_GSC
tristate
depends on SERIAL_8250 && GSC
diff --git a/include/asm-i386/fixmap.h b/include/asm-i386/fixmap.h
index 80ea052..249e753 100644
--- a/include/asm-i386/fixmap.h
+++ b/include/asm-i386/fixmap.h
@@ -54,6 +54,8 @@ extern unsigned long __FIXADDR_TOP;
enum fixed_addresses {
FIX_HOLE,
FIX_VDSO,
+ FIX_DBGP_BASE,
+ FIX_EARLYCON_MEM_BASE,
#ifdef CONFIG_X86_LOCAL_APIC
FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
#endif
diff --git a/include/asm-i386/io.h b/include/asm-i386/io.h
index e797586..7b65b5b 100644
--- a/include/asm-i386/io.h
+++ b/include/asm-i386/io.h
@@ -129,6 +129,7 @@ extern void iounmap(volatile void __iomem *addr);
*/
extern void *bt_ioremap(unsigned long offset, unsigned long size);
extern void bt_iounmap(void *addr, unsigned long size);
+extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys);

/* Use early IO mappings for DMI because it's initialized early */
#define dmi_ioremap bt_ioremap
diff --git a/include/asm-ia64/io.h b/include/asm-ia64/io.h
diff --git a/include/asm-x86_64/fixmap.h b/include/asm-x86_64/fixmap.h
index e90e167..2acb9b7 100644
--- a/include/asm-x86_64/fixmap.h
+++ b/include/asm-x86_64/fixmap.h
@@ -35,6 +35,8 @@ enum fixed_addresses {
VSYSCALL_LAST_PAGE,
VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
VSYSCALL_HPET,
+ FIX_DBGP_BASE,
+ FIX_EARLYCON_MEM_BASE,
FIX_HPET_BASE,
FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
FIX_IO_APIC_BASE_0,
@@ -84,7 +86,7 @@ static __always_inline unsigned long fix_to_virt(const unsigned int idx)
if (idx >= __end_of_fixed_addresses)
__this_fixmap_does_not_exist();

- return __fix_to_virt(idx);
+ return __fix_to_virt(idx);
}

#endif
diff --git a/include/asm-x86_64/io.h b/include/asm-x86_64/io.h
index de2cd9a..7475095 100644
--- a/include/asm-x86_64/io.h
+++ b/include/asm-x86_64/io.h
@@ -144,6 +144,7 @@ extern void early_iounmap(void *addr, unsigned long size);
*/
extern void __iomem * ioremap_nocache (unsigned long offset, unsigned long size);
extern void iounmap(volatile void __iomem *addr);
+extern void __iomem *fix_ioremap(unsigned idx, unsigned long phys);

/*
* ISA I/O bus memory addresses are 1:1 with the physical address.
diff --git a/include/linux/console.h b/include/linux/console.h
index 62ef6e1..c44d3df 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -99,6 +99,7 @@ struct console {
struct tty_driver *(*device)(struct console *, int *);
void (*unblank)(void);
int (*setup)(struct console *, char *);
+ int (*early_setup)(void);
short flags;
short index;
int cflag;
@@ -107,6 +108,7 @@ struct console {
};

extern int add_preferred_console(char *name, int idx, char *options);
+extern int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options);
extern void register_console(struct console *);
extern int unregister_console(struct console *);
extern struct console *console_drivers;
diff --git a/include/linux/serial.h b/include/linux/serial.h
index 33fc8cb..deb7143 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -177,11 +177,5 @@ struct serial_icounter_struct {
#ifdef __KERNEL__
#include <linux/compiler.h>

-/* Allow architectures to override entries in serial8250_ports[] at run time: */
-struct uart_port; /* forward declaration */
-extern int early_serial_setup(struct uart_port *port);
-extern int early_serial_console_init(char *options);
-extern int serial8250_start_console(struct uart_port *port, char *options);
-
#endif /* __KERNEL__ */
#endif /* _LINUX_SERIAL_H */
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 71310d8..23519fb 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -60,4 +60,7 @@ void serial8250_unregister_port(int line);
void serial8250_suspend_port(int line);
void serial8250_resume_port(int line);

+extern int serial8250_find_port(struct uart_port *p);
+extern int serial8250_find_port_for_earlycon(void);
+
#endif
diff --git a/init/main.c b/init/main.c
index eb8bdba..58dbe75 100644
--- a/init/main.c
+++ b/init/main.c
@@ -452,7 +452,10 @@ static int __init do_early_param(char *param, char *val)
struct obs_kernel_param *p;

for (p = __setup_start; p < __setup_end; p++) {
- if (p->early && strcmp(param, p->str) == 0) {
+ if ((p->early && strcmp(param, p->str) == 0) ||
+ (strcmp(param, "console") == 0 &&
+ strcmp(p->str, "earlycon") == 0)
+ ) {
if (p->setup_func(val) != 0)
printk(KERN_WARNING
"Malformed early option '%s'\n", param);
diff --git a/kernel/printk.c b/kernel/printk.c
index 0bbdeac..8779626 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -726,6 +726,25 @@ int __init add_preferred_console(char *name, int idx, char *options)
return 0;
}

+int __init update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
+{
+ struct console_cmdline *c;
+ int i;
+
+ for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
+ if (strcmp(console_cmdline[i].name, name) == 0 &&
+ console_cmdline[i].index == idx) {
+ c = &console_cmdline[i];
+ memcpy(c->name, name_new, sizeof(c->name));
+ c->name[sizeof(c->name) - 1] = 0;
+ c->options = options;
+ c->index = idx_new;
+ return i;
+ }
+ /* not found */
+ return -1;
+}
+
#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND
/**
* suspend_console - suspend the console subsystem
@@ -942,6 +961,9 @@ void register_console(struct console *console)
if (preferred_console < 0 || bootconsole || !console_drivers)
preferred_console = selected_console;

+ if (console->early_setup)
+ console->early_setup();
+
/*
* See if we want to use this console driver. If we
* didn't select a console we take the first one
-
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