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Subject[PATCH v2 2/7] x86/boot: Introduce helpers for serial I/O
Date
As preparatory to enable earlyprintk on non-standard ports on x86,
introduce serial_in() and serial_out() helpers to perform serial I/O.

No functional change intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
arch/x86/boot/boot.h | 2 +
.../boot/compressed/early_serial_console.c | 3 +
arch/x86/boot/compressed/misc.c | 4 +-
arch/x86/boot/compressed/misc.h | 4 ++
arch/x86/boot/early_serial_console.c | 63 +++++++++++++------
arch/x86/boot/tty.c | 7 ++-
6 files changed, 61 insertions(+), 22 deletions(-)

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index f41291903da7..86641b2e83f8 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -299,6 +299,8 @@ int check_knl_erratum(void);
int validate_cpu(void);

/* early_serial_console.c */
+extern unsigned int (*serial_in)(unsigned long addr, int offset);
+extern void (*serial_out)(unsigned long addr, int offset, int value);
extern unsigned long early_serial_base;
void console_init(void);

diff --git a/arch/x86/boot/compressed/early_serial_console.c b/arch/x86/boot/compressed/early_serial_console.c
index 5e3a66478754..4b6269624b59 100644
--- a/arch/x86/boot/compressed/early_serial_console.c
+++ b/arch/x86/boot/compressed/early_serial_console.c
@@ -1,5 +1,8 @@
#include "misc.h"

+unsigned int (*serial_in)(unsigned long addr, int offset);
+void (*serial_out)(unsigned long addr, int offset, int value);
+
unsigned long early_serial_base;

#include "../early_serial_console.c"
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index c0d6c560df69..75b3c8bb92ac 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -98,10 +98,10 @@ static void serial_putchar(int ch)
{
unsigned timeout = 0xffff;

- while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
+ while ((serial_in(early_serial_base, LSR) & XMTRDY) == 0 && --timeout)
cpu_relax();

- outb(ch, early_serial_base + TXR);
+ serial_out(early_serial_base, TXR, ch);
}

void __putstr(const char *s)
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 6f2bdf813949..2fd3ec89a70d 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -110,9 +110,13 @@ static inline void finalize_identity_maps(void)

#ifdef CONFIG_EARLY_PRINTK
/* early_serial_console.c */
+extern unsigned int (*serial_in)(unsigned long addr, int offset);
+extern void (*serial_out)(unsigned long addr, int offset, int value);
extern unsigned long early_serial_base;
void console_init(void);
#else
+static unsigned int (*serial_in)(unsigned long addr, int offset);
+static void (*serial_out)(unsigned long addr, int offset, int value);
static const unsigned long early_serial_base;
static inline void console_init(void)
{ }
diff --git a/arch/x86/boot/early_serial_console.c b/arch/x86/boot/early_serial_console.c
index 2b663beda582..05d02cd4de99 100644
--- a/arch/x86/boot/early_serial_console.c
+++ b/arch/x86/boot/early_serial_console.c
@@ -23,22 +23,45 @@

#define DEFAULT_BAUD 9600

-static void early_serial_init(unsigned long port, int baud)
+static unsigned int io_serial_in(unsigned long addr, int offset)
+{
+ return inb(addr + offset);
+}
+
+static void io_serial_out(unsigned long addr, int offset, int value)
+{
+ outb(value, addr + offset);
+}
+
+static void early_serial_configure(unsigned long port, int baud)
{
unsigned char c;
unsigned divisor;

- outb(0x3, port + LCR); /* 8n1 */
- outb(0, port + IER); /* no interrupt */
- outb(0, port + FCR); /* no fifo */
- outb(0x3, port + MCR); /* DTR + RTS */
+ serial_out(port, LCR, 0x3); /* 8n1 */
+ serial_out(port, IER, 0); /* no interrupt */
+ serial_out(port, FCR, 0); /* no fifo */
+ serial_out(port, MCR, 0x3); /* DTR + RTS */

divisor = 115200 / baud;
- c = inb(port + LCR);
- outb(c | DLAB, port + LCR);
- outb(divisor & 0xff, port + DLL);
- outb((divisor >> 8) & 0xff, port + DLH);
- outb(c & ~DLAB, port + LCR);
+ c = serial_in(port, LCR);
+ serial_out(port, LCR, c | DLAB);
+ serial_out(port, DLL, divisor & 0xff);
+ serial_out(port, DLH, (divisor >> 8) & 0xff);
+ serial_out(port, LCR, c & ~DLAB);
+}
+
+/* Assign serial I/O accessors */
+static void early_serial_use_io_accessors(void)
+{
+ /* These will always be IO based ports */
+ serial_in = io_serial_in;
+ serial_out = io_serial_out;
+}
+
+static void early_serial_init(unsigned long port, int baud)
+{
+ early_serial_configure(port, baud);

early_serial_base = port;
}
@@ -73,6 +96,7 @@ static void parse_earlyprintk(void)
port = DEFAULT_SERIAL_PORT;
else
pos = e - arg;
+ early_serial_use_io_accessors();
} else if (!strncmp(arg + pos, "ttyS", 4)) {
static const int bases[] = { 0x3f8, 0x2f8 };
int idx = 0;
@@ -84,6 +108,7 @@ static void parse_earlyprintk(void)
idx = 1;

port = bases[idx];
+ early_serial_use_io_accessors();
}

if (arg[pos] == ',')
@@ -104,11 +129,11 @@ static unsigned int probe_baud(int port)
unsigned char lcr, dll, dlh;
unsigned int quot;

- lcr = inb(port + LCR);
- outb(lcr | DLAB, port + LCR);
- dll = inb(port + DLL);
- dlh = inb(port + DLH);
- outb(lcr, port + LCR);
+ lcr = serial_in(port, LCR);
+ serial_out(port, LCR, lcr | DLAB);
+ dll = serial_in(port, DLL);
+ dlh = serial_in(port, DLH);
+ serial_out(port, LCR, lcr);
quot = (dlh << 8) | dll;

return BASE_BAUD / quot;
@@ -129,11 +154,13 @@ static void parse_console_uart8250(void)

options = optstr;

- if (!strncmp(options, "uart8250,io,", 12))
+ if (!strncmp(options, "uart8250,io,", 12)) {
port = simple_strtoull(options + 12, &options, 0);
- else if (!strncmp(options, "uart,io,", 8))
+ early_serial_use_io_accessors();
+ } else if (!strncmp(options, "uart,io,", 8)) {
port = simple_strtoull(options + 8, &options, 0);
- else
+ early_serial_use_io_accessors();
+ } else
return;

if (options && (options[0] == ','))
diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c
index d1d34c6ca153..b6aa9db65cda 100644
--- a/arch/x86/boot/tty.c
+++ b/arch/x86/boot/tty.c
@@ -15,6 +15,9 @@

#include "boot.h"

+unsigned int (*serial_in)(unsigned long addr, int offset);
+void (*serial_out)(unsigned long addr, int offset, int value);
+
unsigned long early_serial_base;

#define XMTRDY 0x20
@@ -31,10 +34,10 @@ static void __attribute__((section(".inittext"))) serial_putchar(int ch)
{
unsigned timeout = 0xffff;

- while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
+ while ((serial_in(early_serial_base, LSR) & XMTRDY) == 0 && --timeout)
cpu_relax();

- outb(ch, early_serial_base + TXR);
+ serial_out(early_serial_base, TXR, ch);
}

static void __attribute__((section(".inittext"))) bios_putchar(int ch)
--
2.20.1
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