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/******************************************************************************
* ns16550.c
*
* Driver for 16550-series UARTs. This driver is to be kept within Xen as
* it permits debugging of seriously-toasted machines (e.g., in situations
* where a device driver within a guest OS would be inaccessible).
*
* Copyright (c) 2003-2005, K A Fraser
*/
#include <xen/config.h>
#include <xen/init.h>
#include <xen/irq.h>
#include <xen/sched.h>
#include <xen/serial.h>
#include <asm/io.h>
/* Config serial port with a string <baud>,DPS,<io-base>,<irq>. */
static char opt_com1[30] = "", opt_com2[30] = "";
string_param("com1", opt_com1);
string_param("com2", opt_com2);
static struct ns16550 {
int baud, data_bits, parity, stop_bits, irq;
unsigned long io_base; /* I/O port or memory-mapped I/O address. */
char *remapped_io_base; /* Remapped virtual address of mmap I/O. */
struct irqaction irqaction;
} ns16550_com[2] = {
{ 0, 0, 0, 0, 4, 0x3f8 },
{ 0, 0, 0, 0, 3, 0x2f8 }
};
/* Register offsets */
#define RBR 0x00 /* receive buffer */
#define THR 0x00 /* transmit holding */
#define IER 0x01 /* interrupt enable */
#define IIR 0x02 /* interrupt identity */
#define FCR 0x02 /* FIFO control */
#define LCR 0x03 /* line control */
#define MCR 0x04 /* Modem control */
#define LSR 0x05 /* line status */
#define MSR 0x06 /* Modem status */
#define DLL 0x00 /* divisor latch (ls) (DLAB=1) */
#define DLM 0x01 /* divisor latch (ms) (DLAB=1) */
/* Interrupt Enable Register */
#define IER_ERDAI 0x01 /* rx data recv'd */
#define IER_ETHREI 0x02 /* tx reg. empty */
#define IER_ELSI 0x04 /* rx line status */
#define IER_EMSI 0x08 /* MODEM status */
/* FIFO control register */
#define FCR_ENABLE 0x01 /* enable FIFO */
#define FCR_CLRX 0x02 /* clear Rx FIFO */
#define FCR_CLTX 0x04 /* clear Tx FIFO */
#define FCR_DMA 0x10 /* enter DMA mode */
#define FCR_TRG1 0x00 /* Rx FIFO trig lev 1 */
#define FCR_TRG4 0x40 /* Rx FIFO trig lev 4 */
#define FCR_TRG8 0x80 /* Rx FIFO trig lev 8 */
#define FCR_TRG14 0xc0 /* Rx FIFO trig lev 14 */
/* Line control register */
#define LCR_DLAB 0x80 /* Divisor Latch Access */
/* Modem Control Register */
#define MCR_DTR 0x01 /* Data Terminal Ready */
#define MCR_RTS 0x02 /* Request to Send */
#define MCR_OUT2 0x08 /* OUT2: interrupt mask */
/* Line Status Register */
#define LSR_DR 0x01 /* Data ready */
#define LSR_OE 0x02 /* Overrun */
#define LSR_PE 0x04 /* Parity error */
#define LSR_FE 0x08 /* Framing error */
#define LSR_BI 0x10 /* Break */
#define LSR_THRE 0x20 /* Xmit hold reg empty */
#define LSR_TEMT 0x40 /* Xmitter empty */
#define LSR_ERR 0x80 /* Error */
/* These parity settings can be ORed directly into the LCR. */
#define PARITY_NONE (0<<3)
#define PARITY_ODD (1<<3)
#define PARITY_EVEN (3<<3)
#define PARITY_MARK (5<<3)
#define PARITY_SPACE (7<<3)
static char ns_read_reg(struct ns16550 *uart, int reg)
{
if ( uart->remapped_io_base == NULL )
return inb(uart->io_base + reg);
return readb(uart->remapped_io_base + reg);
}
static void ns_write_reg(struct ns16550 *uart, int reg, char c)
{
if ( uart->remapped_io_base == NULL )
return outb(c, uart->io_base + reg);
writeb(c, uart->remapped_io_base + reg);
}
static void ns16550_interrupt(
int irq, void *dev_id, struct cpu_user_regs *regs)
{
serial_rx_interrupt(dev_id, regs);
}
static void ns16550_putc(struct serial_port *port, char c)
{
struct ns16550 *uart = port->uart;
while ( !(ns_read_reg(uart, LSR) & LSR_THRE) )
cpu_relax();
ns_write_reg(uart, THR, c);
}
static int ns16550_getc(struct serial_port *port, char *pc)
{
struct ns16550 *uart = port->uart;
if ( !(ns_read_reg(uart, LSR) & LSR_DR) )
return 0;
*pc = ns_read_reg(uart, RBR);
return 1;
}
static void ns16550_init_preirq(struct serial_port *port)
{
struct ns16550 *uart = port->uart;
unsigned char lcr;
/* I/O ports are distinguished by their size (16 bits). */
if ( uart->io_base >= 0x10000 )
uart->remapped_io_base = (char *)ioremap(uart->io_base, 8);
lcr = (uart->data_bits - 5) | ((uart->stop_bits - 1) << 2) | uart->parity;
/* No interrupts. */
ns_write_reg(uart, IER, 0);
/* Line control and baud-rate generator. */
ns_write_reg(uart, LCR, lcr | LCR_DLAB);
ns_write_reg(uart, DLL, 115200/uart->baud); /* baud lo */
ns_write_reg(uart, DLM, 0); /* baud hi */
ns_write_reg(uart, LCR, lcr); /* parity, data, stop */
/* No flow ctrl: DTR and RTS are both wedged high to keep remote happy. */
ns_write_reg(uart, MCR, MCR_DTR | MCR_RTS);
/* Enable and clear the FIFOs. Set a large trigger threshold. */
ns_write_reg(uart, FCR, FCR_ENABLE | FCR_CLRX | FCR_CLTX | FCR_TRG14);
}
static void ns16550_init_postirq(struct serial_port *port)
{
struct ns16550 *uart = port->uart;
int rc;
uart->irqaction.handler = ns16550_interrupt;
uart->irqaction.name = "ns16550";
uart->irqaction.dev_id = port;
if ( (rc = setup_irq(uart->irq, &uart->irqaction)) != 0 )
printk("ERROR: Failed to allocate na16550 IRQ %d\n", uart->irq);
/* For sanity, clear the receive FIFO. */
ns_write_reg(uart, FCR, FCR_ENABLE | FCR_CLRX | FCR_TRG14);
/* Master interrupt enable; also keep DTR/RTS asserted. */
ns_write_reg(uart, MCR, MCR_OUT2 | MCR_DTR | MCR_RTS);
/* Enable receive interrupts. */
ns_write_reg(uart, IER, IER_ERDAI);
}
#ifdef CONFIG_X86
#include <asm/physdev.h>
static void ns16550_endboot(struct serial_port *port)
{
struct ns16550 *uart = port->uart;
physdev_modify_ioport_access_range(dom0, 0, uart->io_base, 8);
}
#else
#define ns16550_endboot NULL
#endif
static struct uart_driver ns16550_driver = {
.init_preirq = ns16550_init_preirq,
.init_postirq = ns16550_init_postirq,
.endboot = ns16550_endboot,
.putc = ns16550_putc,
.getc = ns16550_getc
};
#define PARSE_ERR(_f, _a...) \
do { \
printk( "ERROR: " _f "\n" , ## _a ); \
return; \
} while ( 0 )
static void ns16550_parse_port_config(struct ns16550 *uart, char *conf)
{
if ( *conf == '\0' )
return;
uart->baud = simple_strtol(conf, &conf, 10);
if ( (uart->baud < 1200) || (uart->baud > 115200) )
PARSE_ERR("Baud rate %d outside supported range.", uart->baud);
if ( *conf != ',' )
PARSE_ERR("Missing data/parity/stop specifiers.");
conf++;
uart->data_bits = simple_strtol(conf, &conf, 10);
if ( (uart->data_bits < 5) || (uart->data_bits > 8) )
PARSE_ERR("%d data bits are unsupported.", uart->data_bits);
switch ( *conf )
{
case 'n':
uart->parity = PARITY_NONE;
break;
case 'o':
uart->parity = PARITY_ODD;
break;
case 'e':
uart->parity = PARITY_EVEN;
break;
case 'm':
uart->parity = PARITY_MARK;
break;
case 's':
uart->parity = PARITY_SPACE;
break;
default:
PARSE_ERR("Invalid parity specifier '%c'.", *conf);
}
conf++;
uart->stop_bits = simple_strtol(conf, &conf, 10);
if ( (uart->stop_bits < 1) || (uart->stop_bits > 2) )
PARSE_ERR("%d stop bits are unsupported.", uart->stop_bits);
if ( *conf == ',' )
{
conf++;
uart->io_base = simple_strtol(conf, &conf, 0);
if ( *conf == ',' )
{
conf++;
uart->irq = simple_strtol(conf, &conf, 10);
}
}
serial_register_uart(uart - ns16550_com, &ns16550_driver, uart);
}
void ns16550_init(void)
{
ns16550_parse_port_config(&ns16550_com[0], opt_com1);
ns16550_parse_port_config(&ns16550_com[1], opt_com2);
}
/*
* Local variables:
* mode: C
* c-set-style: "BSD"
* c-basic-offset: 4
* tab-width: 4
* indent-tabs-mode: nil
* End:
*/
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