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Commit ea9e9d80 authored by Stuart R. Anderson's avatar Stuart R. Anderson Committed by Greg Kroah-Hartman
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Specify PCI based UART for earlyprintk 



Add support for specifying PCI based UARTs for earlyprintk
using a syntax like "earlyprintk=pciserial,00:18.1,115200",
where 00:18.1 is the BDF of a UART device.

[Slightly tidied from Stuart's original patch]
Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d2b6f447

arch/x86/kernel/early_printk.c

+166 −16
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/usb/ehci_def.h>

#include <linux/efi.h>

#include <asm/efi.h>

#include <asm/pci_x86.h>



/* Simple VGA output */

#define VGABASE		(__ISA_IO_base + 0xb8000)
@@ -76,7 +77,7 @@ static struct console early_vga_console = { 


/* Serial functions loosely based on a similar package from Klaus P. Gerlicher */



static int early_serial_base = 0x3f8;  /* ttyS0 */

static unsigned long early_serial_base = 0x3f8;  /* ttyS0 */



#define XMTRDY          0x20
@@ -94,13 +95,40 @@ static int early_serial_base = 0x3f8; /* ttyS0 */ 
#define DLL             0       /*  Divisor Latch Low         */

#define DLH             1       /*  Divisor latch High        */



static void mem32_serial_out(unsigned long addr, int offset, int value)

{

	uint32_t *vaddr = (uint32_t *)addr;

	/* shift implied by pointer type */

	writel(value, vaddr + offset);

}



static unsigned int mem32_serial_in(unsigned long addr, int offset)

{

	uint32_t *vaddr = (uint32_t *)addr;

	/* shift implied by pointer type */

	return readl(vaddr + offset);

}



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 unsigned int (*serial_in)(unsigned long addr, int offset) = io_serial_in;

static void (*serial_out)(unsigned long addr, int offset, int value) = io_serial_out;



static int early_serial_putc(unsigned char 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);

	return timeout ? 0 : -1;

}
@@ -114,13 +142,28 @@ static void early_serial_write(struct console *con, const char *s, unsigned n) 
	}

}



static __init void early_serial_hw_init(unsigned divisor)

{

	unsigned char c;



	serial_out(early_serial_base, LCR, 0x3);	/* 8n1 */

	serial_out(early_serial_base, IER, 0);	/* no interrupt */

	serial_out(early_serial_base, FCR, 0);	/* no fifo */

	serial_out(early_serial_base, MCR, 0x3);	/* DTR + RTS */



	c = serial_in(early_serial_base, LCR);

	serial_out(early_serial_base, LCR, c | DLAB);

	serial_out(early_serial_base, DLL, divisor & 0xff);

	serial_out(early_serial_base, DLH, (divisor >> 8) & 0xff);

	serial_out(early_serial_base, LCR, c & ~DLAB);

}



#define DEFAULT_BAUD 9600



static __init void early_serial_init(char *s)

{

	unsigned char c;

	unsigned divisor;

	unsigned baud = DEFAULT_BAUD;

	unsigned long baud = DEFAULT_BAUD;

	char *e;



	if (*s == ',')
@@ -145,24 +188,124 @@ static __init void early_serial_init(char *s) 
			s++;

	}



	outb(0x3, early_serial_base + LCR);	/* 8n1 */

	outb(0, early_serial_base + IER);	/* no interrupt */

	outb(0, early_serial_base + FCR);	/* no fifo */

	outb(0x3, early_serial_base + MCR);	/* DTR + RTS */

	if (*s) {

		if (kstrtoul(s, 0, &baud) < 0 || baud == 0)

			baud = DEFAULT_BAUD;

	}



	/* Convert from baud to divisor value */

	divisor = 115200 / baud;



	/* These will always be IO based ports */

	serial_in = io_serial_in;

	serial_out = io_serial_out;



	/* Set up the HW */

	early_serial_hw_init(divisor);

}



#ifdef CONFIG_PCI

/*

 * early_pci_serial_init()

 *

 * This function is invoked when the early_printk param starts with "pciserial"

 * The rest of the param should be ",B:D.F,baud" where B, D & F describe the

 * location of a PCI device that must be a UART device.

 */

static __init void early_pci_serial_init(char *s)

{

	unsigned divisor;

	unsigned long baud = DEFAULT_BAUD;

	u8 bus, slot, func;

	uint32_t classcode, bar0;

	uint16_t cmdreg;

	char *e;





	/*

	 * First, part the param to get the BDF values

	 */

	if (*s == ',')

		++s;



	if (*s == 0)

		return;



	bus = (u8)simple_strtoul(s, &e, 16);

	s = e;

	if (*s != ':')

		return;

	++s;

	slot = (u8)simple_strtoul(s, &e, 16);

	s = e;

	if (*s != '.')

		return;

	++s;

	func = (u8)simple_strtoul(s, &e, 16);

	s = e;



	/* A baud might be following */

	if (*s == ',')

		s++;



	/*

	 * Second, find the device from the BDF

	 */

	cmdreg = read_pci_config(bus, slot, func, PCI_COMMAND);

	classcode = read_pci_config(bus, slot, func, PCI_CLASS_REVISION);

	bar0 = read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);



	/*

	 * Verify it is a UART type device

	 */

	if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) &&

	     (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) ||

	   (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */

		return;



	/*

	 * Determine if it is IO or memory mapped

	 */

	if (bar0 & 0x01) {

		/* it is IO mapped */

		serial_in = io_serial_in;

		serial_out = io_serial_out;

		early_serial_base = bar0&0xfffffffc;

		write_pci_config(bus, slot, func, PCI_COMMAND,

						cmdreg|PCI_COMMAND_IO);

	} else {

		/* It is memory mapped - assume 32-bit alignment */

		serial_in = mem32_serial_in;

		serial_out = mem32_serial_out;

		/* WARNING! assuming the address is always in the first 4G */

		early_serial_base =

			(unsigned long)early_ioremap(bar0 & 0xfffffff0, 0x10);

		write_pci_config(bus, slot, func, PCI_COMMAND,

						cmdreg|PCI_COMMAND_MEMORY);

	}



	/*

	 * Lastly, initalize the hardware

	 */

	if (*s) {

		baud = simple_strtoul(s, &e, 0);

		if (baud == 0 || s == e)

		if (strcmp(s, "nocfg") == 0)

			/* Sometimes, we want to leave the UART alone

			 * and assume the BIOS has set it up correctly.

			 * "nocfg" tells us this is the case, and we

			 * should do no more setup.

			 */

			return;

		if (kstrtoul(s, 0, &baud) < 0 || baud == 0)

			baud = DEFAULT_BAUD;

	}



	/* Convert from baud to divisor value */

	divisor = 115200 / baud;

	c = inb(early_serial_base + LCR);

	outb(c | DLAB, early_serial_base + LCR);

	outb(divisor & 0xff, early_serial_base + DLL);

	outb((divisor >> 8) & 0xff, early_serial_base + DLH);

	outb(c & ~DLAB, early_serial_base + LCR);



	/* Set up the HW */

	early_serial_hw_init(divisor);

}

#endif



static struct console early_serial_console = {

	.name =		"earlyser",
@@ -210,6 +353,13 @@ static int __init setup_early_printk(char *buf) 
			early_serial_init(buf + 4);

			early_console_register(&early_serial_console, keep);

		}

#ifdef CONFIG_PCI

		if (!strncmp(buf, "pciserial", 9)) {

			early_pci_serial_init(buf + 9);

			early_console_register(&early_serial_console, keep);

			buf += 9; /* Keep from match the above "serial" */

		}

#endif

		if (!strncmp(buf, "vga", 3) &&

		    boot_params.screen_info.orig_video_isVGA == 1) {

			max_xpos = boot_params.screen_info.orig_video_cols;