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8250.c
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8250.c
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/*
* linux/drivers/char/8250.c
*
* Driver for 8250/16550-type serial ports
*
* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
*
* Copyright (C) 2001 Russell King.
*
* 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.
*
* $Id: 8250.c,v 1.90 2002/07/28 10:03:27 rmk Exp $
*
* A note about mapbase / membase
*
* mapbase is the physical address of the IO port.
* membase is an 'ioremapped' cookie.
*/
#include <linux/config.h>
#if defined(CONFIG_SERIAL_8250_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_reg.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/serial_8250.h>
#include <linux/nmi.h>
#include <linux/mutex.h>
#include <asm/io.h>
#include <asm/irq.h>
#include "8250.h"
/*
* Configuration:
* share_irqs - whether we pass SA_SHIRQ to request_irq(). This option
* is unsafe when used on edge-triggered interrupts.
*/
static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
static unsigned int nr_uarts = CONFIG_SERIAL_8250_RUNTIME_UARTS;
/*
* Debugging.
*/
#if 0
#define DEBUG_AUTOCONF(fmt...) printk(fmt)
#else
#define DEBUG_AUTOCONF(fmt...) do { } while (0)
#endif
#if 0
#define DEBUG_INTR(fmt...) printk(fmt)
#else
#define DEBUG_INTR(fmt...) do { } while (0)
#endif
#define PASS_LIMIT 256
/*
* We default to IRQ0 for the "no irq" hack. Some
* machine types want others as well - they're free
* to redefine this in their header file.
*/
#define is_real_interrupt(irq) ((irq) != 0)
#ifdef CONFIG_SERIAL_8250_DETECT_IRQ
#define CONFIG_SERIAL_DETECT_IRQ 1
#endif
#ifdef CONFIG_SERIAL_8250_MANY_PORTS
#define CONFIG_SERIAL_MANY_PORTS 1
#endif
/*
* HUB6 is always on. This will be removed once the header
* files have been cleaned.
*/
#define CONFIG_HUB6 1
#include <asm/serial.h>
/*
* SERIAL_PORT_DFNS tells us about built-in ports that have no
* standard enumeration mechanism. Platforms that can find all
* serial ports via mechanisms like ACPI or PCI need not supply it.
*/
#ifndef SERIAL_PORT_DFNS
#define SERIAL_PORT_DFNS
#endif
static const struct old_serial_port old_serial_port[] = {
SERIAL_PORT_DFNS /* defined in asm/serial.h */
};
#define UART_NR CONFIG_SERIAL_8250_NR_UARTS
#ifdef CONFIG_SERIAL_8250_RSA
#define PORT_RSA_MAX 4
static unsigned long probe_rsa[PORT_RSA_MAX];
static unsigned int probe_rsa_count;
#endif /* CONFIG_SERIAL_8250_RSA */
struct uart_8250_port {
struct uart_port port;
struct timer_list timer; /* "no irq" timer */
struct list_head list; /* ports on this IRQ */
unsigned short capabilities; /* port capabilities */
unsigned short bugs; /* port bugs */
unsigned int tx_loadsz; /* transmit fifo load size */
unsigned char acr;
unsigned char ier;
unsigned char lcr;
unsigned char mcr;
unsigned char mcr_mask; /* mask of user bits */
unsigned char mcr_force; /* mask of forced bits */
unsigned char lsr_break_flag;
/*
* We provide a per-port pm hook.
*/
void (*pm)(struct uart_port *port,
unsigned int state, unsigned int old);
};
struct irq_info {
spinlock_t lock;
struct list_head *head;
};
static struct irq_info irq_lists[NR_IRQS];
/*
* Here we define the default xmit fifo size used for each type of UART.
*/
static const struct serial8250_config uart_config[] = {
[PORT_UNKNOWN] = {
.name = "unknown",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_8250] = {
.name = "8250",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16450] = {
.name = "16450",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16550] = {
.name = "16550",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16550A] = {
.name = "16550A",
.fifo_size = 16,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO,
},
[PORT_CIRRUS] = {
.name = "Cirrus",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16650] = {
.name = "ST16650",
.fifo_size = 1,
.tx_loadsz = 1,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16650V2] = {
.name = "ST16650V2",
.fifo_size = 32,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
UART_FCR_T_TRIG_00,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16750] = {
.name = "TI16750",
.fifo_size = 64,
.tx_loadsz = 64,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10 |
UART_FCR7_64BYTE,
.flags = UART_CAP_FIFO | UART_CAP_SLEEP | UART_CAP_AFE,
},
[PORT_STARTECH] = {
.name = "Startech",
.fifo_size = 1,
.tx_loadsz = 1,
},
[PORT_16C950] = {
.name = "16C950/954",
.fifo_size = 128,
.tx_loadsz = 128,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO,
},
[PORT_16654] = {
.name = "ST16654",
.fifo_size = 64,
.tx_loadsz = 32,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01 |
UART_FCR_T_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_16850] = {
.name = "XR16850",
.fifo_size = 128,
.tx_loadsz = 128,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
},
[PORT_RSA] = {
.name = "RSA",
.fifo_size = 2048,
.tx_loadsz = 2048,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_11,
.flags = UART_CAP_FIFO,
},
[PORT_NS16550A] = {
.name = "NS16550A",
.fifo_size = 16,
.tx_loadsz = 16,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_NATSEMI,
},
[PORT_XSCALE] = {
.name = "XScale",
.fifo_size = 32,
.tx_loadsz = 32,
.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
.flags = UART_CAP_FIFO | UART_CAP_UUE,
},
};
#ifdef CONFIG_SERIAL_8250_AU1X00
/* Au1x00 UART hardware has a weird register layout */
static const u8 au_io_in_map[] = {
[UART_RX] = 0,
[UART_IER] = 2,
[UART_IIR] = 3,
[UART_LCR] = 5,
[UART_MCR] = 6,
[UART_LSR] = 7,
[UART_MSR] = 8,
};
static const u8 au_io_out_map[] = {
[UART_TX] = 1,
[UART_IER] = 2,
[UART_FCR] = 4,
[UART_LCR] = 5,
[UART_MCR] = 6,
};
/* sane hardware needs no mapping */
static inline int map_8250_in_reg(struct uart_8250_port *up, int offset)
{
if (up->port.iotype != UPIO_AU)
return offset;
return au_io_in_map[offset];
}
static inline int map_8250_out_reg(struct uart_8250_port *up, int offset)
{
if (up->port.iotype != UPIO_AU)
return offset;
return au_io_out_map[offset];
}
#else
/* sane hardware needs no mapping */
#define map_8250_in_reg(up, offset) (offset)
#define map_8250_out_reg(up, offset) (offset)
#endif
static unsigned int serial_in(struct uart_8250_port *up, int offset)
{
offset = map_8250_in_reg(up, offset) << up->port.regshift;
switch (up->port.iotype) {
case UPIO_HUB6:
outb(up->port.hub6 - 1 + offset, up->port.iobase);
return inb(up->port.iobase + 1);
case UPIO_MEM:
return readb(up->port.membase + offset);
case UPIO_MEM32:
return readl(up->port.membase + offset);
#ifdef CONFIG_SERIAL_8250_AU1X00
case UPIO_AU:
return __raw_readl(up->port.membase + offset);
#endif
default:
return inb(up->port.iobase + offset);
}
}
static void
serial_out(struct uart_8250_port *up, int offset, int value)
{
offset = map_8250_out_reg(up, offset) << up->port.regshift;
switch (up->port.iotype) {
case UPIO_HUB6:
outb(up->port.hub6 - 1 + offset, up->port.iobase);
outb(value, up->port.iobase + 1);
break;
case UPIO_MEM:
writeb(value, up->port.membase + offset);
break;
case UPIO_MEM32:
writel(value, up->port.membase + offset);
break;
#ifdef CONFIG_SERIAL_8250_AU1X00
case UPIO_AU:
__raw_writel(value, up->port.membase + offset);
break;
#endif
default:
outb(value, up->port.iobase + offset);
}
}
/*
* We used to support using pause I/O for certain machines. We
* haven't supported this for a while, but just in case it's badly
* needed for certain old 386 machines, I've left these #define's
* in....
*/
#define serial_inp(up, offset) serial_in(up, offset)
#define serial_outp(up, offset, value) serial_out(up, offset, value)
/*
* For the 16C950
*/
static void serial_icr_write(struct uart_8250_port *up, int offset, int value)
{
serial_out(up, UART_SCR, offset);
serial_out(up, UART_ICR, value);
}
static unsigned int serial_icr_read(struct uart_8250_port *up, int offset)
{
unsigned int value;
serial_icr_write(up, UART_ACR, up->acr | UART_ACR_ICRRD);
serial_out(up, UART_SCR, offset);
value = serial_in(up, UART_ICR);
serial_icr_write(up, UART_ACR, up->acr);
return value;
}
/*
* FIFO support.
*/
static inline void serial8250_clear_fifos(struct uart_8250_port *p)
{
if (p->capabilities & UART_CAP_FIFO) {
serial_outp(p, UART_FCR, UART_FCR_ENABLE_FIFO);
serial_outp(p, UART_FCR, UART_FCR_ENABLE_FIFO |
UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
serial_outp(p, UART_FCR, 0);
}
}
/*
* IER sleep support. UARTs which have EFRs need the "extended
* capability" bit enabled. Note that on XR16C850s, we need to
* reset LCR to write to IER.
*/
static inline void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
{
if (p->capabilities & UART_CAP_SLEEP) {
if (p->capabilities & UART_CAP_EFR) {
serial_outp(p, UART_LCR, 0xBF);
serial_outp(p, UART_EFR, UART_EFR_ECB);
serial_outp(p, UART_LCR, 0);
}
serial_outp(p, UART_IER, sleep ? UART_IERX_SLEEP : 0);
if (p->capabilities & UART_CAP_EFR) {
serial_outp(p, UART_LCR, 0xBF);
serial_outp(p, UART_EFR, 0);
serial_outp(p, UART_LCR, 0);
}
}
}
#ifdef CONFIG_SERIAL_8250_RSA
/*
* Attempts to turn on the RSA FIFO. Returns zero on failure.
* We set the port uart clock rate if we succeed.
*/
static int __enable_rsa(struct uart_8250_port *up)
{
unsigned char mode;
int result;
mode = serial_inp(up, UART_RSA_MSR);
result = mode & UART_RSA_MSR_FIFO;
if (!result) {
serial_outp(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO);
mode = serial_inp(up, UART_RSA_MSR);
result = mode & UART_RSA_MSR_FIFO;
}
if (result)
up->port.uartclk = SERIAL_RSA_BAUD_BASE * 16;
return result;
}
static void enable_rsa(struct uart_8250_port *up)
{
if (up->port.type == PORT_RSA) {
if (up->port.uartclk != SERIAL_RSA_BAUD_BASE * 16) {
spin_lock_irq(&up->port.lock);
__enable_rsa(up);
spin_unlock_irq(&up->port.lock);
}
if (up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16)
serial_outp(up, UART_RSA_FRR, 0);
}
}
/*
* Attempts to turn off the RSA FIFO. Returns zero on failure.
* It is unknown why interrupts were disabled in here. However,
* the caller is expected to preserve this behaviour by grabbing
* the spinlock before calling this function.
*/
static void disable_rsa(struct uart_8250_port *up)
{
unsigned char mode;
int result;
if (up->port.type == PORT_RSA &&
up->port.uartclk == SERIAL_RSA_BAUD_BASE * 16) {
spin_lock_irq(&up->port.lock);
mode = serial_inp(up, UART_RSA_MSR);
result = !(mode & UART_RSA_MSR_FIFO);
if (!result) {
serial_outp(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
mode = serial_inp(up, UART_RSA_MSR);
result = !(mode & UART_RSA_MSR_FIFO);
}
if (result)
up->port.uartclk = SERIAL_RSA_BAUD_BASE_LO * 16;
spin_unlock_irq(&up->port.lock);
}
}
#endif /* CONFIG_SERIAL_8250_RSA */
/*
* This is a quickie test to see how big the FIFO is.
* It doesn't work at all the time, more's the pity.
*/
static int size_fifo(struct uart_8250_port *up)
{
unsigned char old_fcr, old_mcr, old_dll, old_dlm, old_lcr;
int count;
old_lcr = serial_inp(up, UART_LCR);
serial_outp(up, UART_LCR, 0);
old_fcr = serial_inp(up, UART_FCR);
old_mcr = serial_inp(up, UART_MCR);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO |
UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
serial_outp(up, UART_MCR, UART_MCR_LOOP);
serial_outp(up, UART_LCR, UART_LCR_DLAB);
old_dll = serial_inp(up, UART_DLL);
old_dlm = serial_inp(up, UART_DLM);
serial_outp(up, UART_DLL, 0x01);
serial_outp(up, UART_DLM, 0x00);
serial_outp(up, UART_LCR, 0x03);
for (count = 0; count < 256; count++)
serial_outp(up, UART_TX, count);
mdelay(20);/* FIXME - schedule_timeout */
for (count = 0; (serial_inp(up, UART_LSR) & UART_LSR_DR) &&
(count < 256); count++)
serial_inp(up, UART_RX);
serial_outp(up, UART_FCR, old_fcr);
serial_outp(up, UART_MCR, old_mcr);
serial_outp(up, UART_LCR, UART_LCR_DLAB);
serial_outp(up, UART_DLL, old_dll);
serial_outp(up, UART_DLM, old_dlm);
serial_outp(up, UART_LCR, old_lcr);
return count;
}
/*
* Read UART ID using the divisor method - set DLL and DLM to zero
* and the revision will be in DLL and device type in DLM. We
* preserve the device state across this.
*/
static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
{
unsigned char old_dll, old_dlm, old_lcr;
unsigned int id;
old_lcr = serial_inp(p, UART_LCR);
serial_outp(p, UART_LCR, UART_LCR_DLAB);
old_dll = serial_inp(p, UART_DLL);
old_dlm = serial_inp(p, UART_DLM);
serial_outp(p, UART_DLL, 0);
serial_outp(p, UART_DLM, 0);
id = serial_inp(p, UART_DLL) | serial_inp(p, UART_DLM) << 8;
serial_outp(p, UART_DLL, old_dll);
serial_outp(p, UART_DLM, old_dlm);
serial_outp(p, UART_LCR, old_lcr);
return id;
}
/*
* This is a helper routine to autodetect StarTech/Exar/Oxsemi UART's.
* When this function is called we know it is at least a StarTech
* 16650 V2, but it might be one of several StarTech UARTs, or one of
* its clones. (We treat the broken original StarTech 16650 V1 as a
* 16550, and why not? Startech doesn't seem to even acknowledge its
* existence.)
*
* What evil have men's minds wrought...
*/
static void autoconfig_has_efr(struct uart_8250_port *up)
{
unsigned int id1, id2, id3, rev;
/*
* Everything with an EFR has SLEEP
*/
up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
/*
* First we check to see if it's an Oxford Semiconductor UART.
*
* If we have to do this here because some non-National
* Semiconductor clone chips lock up if you try writing to the
* LSR register (which serial_icr_read does)
*/
/*
* Check for Oxford Semiconductor 16C950.
*
* EFR [4] must be set else this test fails.
*
* This shouldn't be necessary, but Mike Hudson ([email protected])
* claims that it's needed for 952 dual UART's (which are not
* recommended for new designs).
*/
up->acr = 0;
serial_out(up, UART_LCR, 0xBF);
serial_out(up, UART_EFR, UART_EFR_ECB);
serial_out(up, UART_LCR, 0x00);
id1 = serial_icr_read(up, UART_ID1);
id2 = serial_icr_read(up, UART_ID2);
id3 = serial_icr_read(up, UART_ID3);
rev = serial_icr_read(up, UART_REV);
DEBUG_AUTOCONF("950id=%02x:%02x:%02x:%02x ", id1, id2, id3, rev);
if (id1 == 0x16 && id2 == 0xC9 &&
(id3 == 0x50 || id3 == 0x52 || id3 == 0x54)) {
up->port.type = PORT_16C950;
/*
* Enable work around for the Oxford Semiconductor 952 rev B
* chip which causes it to seriously miscalculate baud rates
* when DLL is 0.
*/
if (id3 == 0x52 && rev == 0x01)
up->bugs |= UART_BUG_QUOT;
return;
}
/*
* We check for a XR16C850 by setting DLL and DLM to 0, and then
* reading back DLL and DLM. The chip type depends on the DLM
* value read back:
* 0x10 - XR16C850 and the DLL contains the chip revision.
* 0x12 - XR16C2850.
* 0x14 - XR16C854.
*/
id1 = autoconfig_read_divisor_id(up);
DEBUG_AUTOCONF("850id=%04x ", id1);
id2 = id1 >> 8;
if (id2 == 0x10 || id2 == 0x12 || id2 == 0x14) {
up->port.type = PORT_16850;
return;
}
/*
* It wasn't an XR16C850.
*
* We distinguish between the '654 and the '650 by counting
* how many bytes are in the FIFO. I'm using this for now,
* since that's the technique that was sent to me in the
* serial driver update, but I'm not convinced this works.
* I've had problems doing this in the past. -TYT
*/
if (size_fifo(up) == 64)
up->port.type = PORT_16654;
else
up->port.type = PORT_16650V2;
}
/*
* We detected a chip without a FIFO. Only two fall into
* this category - the original 8250 and the 16450. The
* 16450 has a scratch register (accessible with LCR=0)
*/
static void autoconfig_8250(struct uart_8250_port *up)
{
unsigned char scratch, status1, status2;
up->port.type = PORT_8250;
scratch = serial_in(up, UART_SCR);
serial_outp(up, UART_SCR, 0xa5);
status1 = serial_in(up, UART_SCR);
serial_outp(up, UART_SCR, 0x5a);
status2 = serial_in(up, UART_SCR);
serial_outp(up, UART_SCR, scratch);
if (status1 == 0xa5 && status2 == 0x5a)
up->port.type = PORT_16450;
}
static int broken_efr(struct uart_8250_port *up)
{
/*
* Exar ST16C2550 "A2" devices incorrectly detect as
* having an EFR, and report an ID of 0x0201. See
* http://www.exar.com/info.php?pdf=dan180_oct2004.pdf
*/
if (autoconfig_read_divisor_id(up) == 0x0201 && size_fifo(up) == 16)
return 1;
return 0;
}
/*
* We know that the chip has FIFOs. Does it have an EFR? The
* EFR is located in the same register position as the IIR and
* we know the top two bits of the IIR are currently set. The
* EFR should contain zero. Try to read the EFR.
*/
static void autoconfig_16550a(struct uart_8250_port *up)
{
unsigned char status1, status2;
unsigned int iersave;
up->port.type = PORT_16550A;
up->capabilities |= UART_CAP_FIFO;
/*
* Check for presence of the EFR when DLAB is set.
* Only ST16C650V1 UARTs pass this test.
*/
serial_outp(up, UART_LCR, UART_LCR_DLAB);
if (serial_in(up, UART_EFR) == 0) {
serial_outp(up, UART_EFR, 0xA8);
if (serial_in(up, UART_EFR) != 0) {
DEBUG_AUTOCONF("EFRv1 ");
up->port.type = PORT_16650;
up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
} else {
DEBUG_AUTOCONF("Motorola 8xxx DUART ");
}
serial_outp(up, UART_EFR, 0);
return;
}
/*
* Maybe it requires 0xbf to be written to the LCR.
* (other ST16C650V2 UARTs, TI16C752A, etc)
*/
serial_outp(up, UART_LCR, 0xBF);
if (serial_in(up, UART_EFR) == 0 && !broken_efr(up)) {
DEBUG_AUTOCONF("EFRv2 ");
autoconfig_has_efr(up);
return;
}
/*
* Check for a National Semiconductor SuperIO chip.
* Attempt to switch to bank 2, read the value of the LOOP bit
* from EXCR1. Switch back to bank 0, change it in MCR. Then
* switch back to bank 2, read it from EXCR1 again and check
* it's changed. If so, set baud_base in EXCR2 to 921600. -- dwmw2
*/
serial_outp(up, UART_LCR, 0);
status1 = serial_in(up, UART_MCR);
serial_outp(up, UART_LCR, 0xE0);
status2 = serial_in(up, 0x02); /* EXCR1 */
if (!((status2 ^ status1) & UART_MCR_LOOP)) {
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_MCR, status1 ^ UART_MCR_LOOP);
serial_outp(up, UART_LCR, 0xE0);
status2 = serial_in(up, 0x02); /* EXCR1 */
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_MCR, status1);
if ((status2 ^ status1) & UART_MCR_LOOP) {
unsigned short quot;
serial_outp(up, UART_LCR, 0xE0);
quot = serial_inp(up, UART_DLM) << 8;
quot += serial_inp(up, UART_DLL);
quot <<= 3;
status1 = serial_in(up, 0x04); /* EXCR1 */
status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */
status1 |= 0x10; /* 1.625 divisor for baud_base --> 921600 */
serial_outp(up, 0x04, status1);
serial_outp(up, UART_DLL, quot & 0xff);
serial_outp(up, UART_DLM, quot >> 8);
serial_outp(up, UART_LCR, 0);
up->port.uartclk = 921600*16;
up->port.type = PORT_NS16550A;
up->capabilities |= UART_NATSEMI;
return;
}
}
/*
* No EFR. Try to detect a TI16750, which only sets bit 5 of
* the IIR when 64 byte FIFO mode is enabled when DLAB is set.
* Try setting it with and without DLAB set. Cheap clones
* set bit 5 without DLAB set.
*/
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
status1 = serial_in(up, UART_IIR) >> 5;
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
serial_outp(up, UART_LCR, UART_LCR_DLAB);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
status2 = serial_in(up, UART_IIR) >> 5;
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
serial_outp(up, UART_LCR, 0);
DEBUG_AUTOCONF("iir1=%d iir2=%d ", status1, status2);
if (status1 == 6 && status2 == 7) {
up->port.type = PORT_16750;
up->capabilities |= UART_CAP_AFE | UART_CAP_SLEEP;
return;
}
/*
* Try writing and reading the UART_IER_UUE bit (b6).
* If it works, this is probably one of the Xscale platform's
* internal UARTs.
* We're going to explicitly set the UUE bit to 0 before
* trying to write and read a 1 just to make sure it's not
* already a 1 and maybe locked there before we even start start.
*/
iersave = serial_in(up, UART_IER);
serial_outp(up, UART_IER, iersave & ~UART_IER_UUE);
if (!(serial_in(up, UART_IER) & UART_IER_UUE)) {
/*
* OK it's in a known zero state, try writing and reading
* without disturbing the current state of the other bits.
*/
serial_outp(up, UART_IER, iersave | UART_IER_UUE);
if (serial_in(up, UART_IER) & UART_IER_UUE) {
/*
* It's an Xscale.
* We'll leave the UART_IER_UUE bit set to 1 (enabled).
*/
DEBUG_AUTOCONF("Xscale ");
up->port.type = PORT_XSCALE;
up->capabilities |= UART_CAP_UUE;
return;
}
} else {
/*
* If we got here we couldn't force the IER_UUE bit to 0.
* Log it and continue.
*/
DEBUG_AUTOCONF("Couldn't force IER_UUE to 0 ");
}
serial_outp(up, UART_IER, iersave);
}
/*
* This routine is called by rs_init() to initialize a specific serial
* port. It determines what type of UART chip this serial port is
* using: 8250, 16450, 16550, 16550A. The important question is
* whether or not this UART is a 16550A or not, since this will
* determine whether or not we can use its FIFO features or not.
*/
static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
{
unsigned char status1, scratch, scratch2, scratch3;
unsigned char save_lcr, save_mcr;
unsigned long flags;
if (!up->port.iobase && !up->port.mapbase && !up->port.membase)
return;
DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04x, 0x%p): ",
up->port.line, up->port.iobase, up->port.membase);
/*
* We really do need global IRQs disabled here - we're going to
* be frobbing the chips IRQ enable register to see if it exists.
*/
spin_lock_irqsave(&up->port.lock, flags);
// save_flags(flags); cli();
up->capabilities = 0;
up->bugs = 0;
if (!(up->port.flags & UPF_BUGGY_UART)) {
/*
* Do a simple existence test first; if we fail this,
* there's no point trying anything else.
*
* 0x80 is used as a nonsense port to prevent against
* false positives due to ISA bus float. The
* assumption is that 0x80 is a non-existent port;
* which should be safe since include/asm/io.h also
* makes this assumption.
*
* Note: this is safe as long as MCR bit 4 is clear
* and the device is in "PC" mode.
*/
scratch = serial_inp(up, UART_IER);
serial_outp(up, UART_IER, 0);
#ifdef __i386__
outb(0xff, 0x080);
#endif
scratch2 = serial_inp(up, UART_IER);
serial_outp(up, UART_IER, 0x0F);
#ifdef __i386__
outb(0, 0x080);
#endif
scratch3 = serial_inp(up, UART_IER);
serial_outp(up, UART_IER, scratch);
if (scratch2 != 0 || scratch3 != 0x0F) {
/*
* We failed; there's nothing here
*/
DEBUG_AUTOCONF("IER test failed (%02x, %02x) ",
scratch2, scratch3);
goto out;
}
}
save_mcr = serial_in(up, UART_MCR);
save_lcr = serial_in(up, UART_LCR);
/*
* Check to see if a UART is really there. Certain broken
* internal modems based on the Rockwell chipset fail this
* test, because they apparently don't implement the loopback
* test mode. So this test is skipped on the COM 1 through
* COM 4 ports. This *should* be safe, since no board
* manufacturer would be stupid enough to design a board
* that conflicts with COM 1-4 --- we hope!
*/
if (!(up->port.flags & UPF_SKIP_TEST)) {
serial_outp(up, UART_MCR, UART_MCR_LOOP | 0x0A);
status1 = serial_inp(up, UART_MSR) & 0xF0;
serial_outp(up, UART_MCR, save_mcr);
if (status1 != 0x90) {
DEBUG_AUTOCONF("LOOP test failed (%02x) ",
status1);
goto out;
}
}
/*
* We're pretty sure there's a port here. Lets find out what
* type of port it is. The IIR top two bits allows us to find
* out if it's 8250 or 16450, 16550, 16550A or later. This
* determines what we test for next.
*
* We also initialise the EFR (if any) to zero for later. The
* EFR occupies the same register location as the FCR and IIR.
*/
serial_outp(up, UART_LCR, 0xBF);
serial_outp(up, UART_EFR, 0);
serial_outp(up, UART_LCR, 0);
serial_outp(up, UART_FCR, UART_FCR_ENABLE_FIFO);
scratch = serial_in(up, UART_IIR) >> 6;
DEBUG_AUTOCONF("iir=%d ", scratch);
switch (scratch) {
case 0:
autoconfig_8250(up);
break;
case 1:
up->port.type = PORT_UNKNOWN;
break;
case 2:
up->port.type = PORT_16550;
break;
case 3:
autoconfig_16550a(up);
break;
}
#ifdef CONFIG_SERIAL_8250_RSA
/*
* Only probe for RSA ports if we got the region.
*/
if (up->port.type == PORT_16550A && probeflags & PROBE_RSA) {
int i;
for (i = 0 ; i < probe_rsa_count; ++i) {
if (probe_rsa[i] == up->port.iobase &&
__enable_rsa(up)) {
up->port.type = PORT_RSA;
break;
}
}
}
#endif
#ifdef CONFIG_SERIAL_8250_AU1X00
/* if access method is AU, it is a 16550 with a quirk */
if (up->port.type == PORT_16550A && up->port.iotype == UPIO_AU)
up->bugs |= UART_BUG_NOMSR;
#endif
serial_outp(up, UART_LCR, save_lcr);
if (up->capabilities != uart_config[up->port.type].flags) {
printk(KERN_WARNING
"ttyS%d: detected caps %08x should be %08x\n",
up->port.line, up->capabilities,
uart_config[up->port.type].flags);
}
up->port.fifosize = uart_config[up->port.type].fifo_size;
up->capabilities = uart_config[up->port.type].flags;
up->tx_loadsz = uart_config[up->port.type].tx_loadsz;
if (up->port.type == PORT_UNKNOWN)
goto out;
/*
* Reset the UART.
*/
#ifdef CONFIG_SERIAL_8250_RSA
if (up->port.type == PORT_RSA)
serial_outp(up, UART_RSA_FRR, 0);
#endif