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grub2/grub-core/term/ns8250.c
Daniel Baumann 6a7a3b2a63
Adding upstream version 2.12. 
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
2025-06-22 15:25:07 +02:00

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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2000,2001,2002,2003,2004,2005,2007,2008,2009,2010 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/serial.h>
#include <grub/ns8250.h>
#include <grub/types.h>
#include <grub/dl.h>
#include <grub/misc.h>
#include <grub/cpu/io.h>
#include <grub/mm.h>
#include <grub/time.h>
#include <grub/i18n.h>
#ifdef GRUB_MACHINE_PCBIOS
#include <grub/machine/memory.h>
#define GRUB_SERIAL_PORT_NUM 4
#else
#include <grub/machine/serial.h>
static const grub_port_t serial_hw_io_addr[] = GRUB_MACHINE_SERIAL_PORTS;
#define GRUB_SERIAL_PORT_NUM (ARRAY_SIZE(serial_hw_io_addr))
#endif
static int dead_ports = 0;
static grub_uint8_t
ns8250_reg_read (struct grub_serial_port *port, grub_addr_t reg)
{
asm volatile("" : : : "memory");
if (port->use_mmio == true)
{
/*
* Note: we assume MMIO UARTs are little endian. This is not true of all
* embedded platforms but will do for now.
*/
switch(port->mmio.access_size)
{
default:
/* ACPI tables occasionally uses "0" (legacy) as equivalent to "1" (byte). */
case 1:
return *((volatile grub_uint8_t *) (port->mmio.base + reg));
case 2:
return grub_le_to_cpu16 (*((volatile grub_uint16_t *) (port->mmio.base + (reg << 1))));
case 3:
return grub_le_to_cpu32 (*((volatile grub_uint32_t *) (port->mmio.base + (reg << 2))));
case 4:
/*
* This will only work properly on 64-bit systems since 64-bit
* accessors aren't atomic on 32-bit hardware. Thankfully the
* case of a UART with a 64-bit register spacing on 32-bit
* also probably doesn't exist.
*/
return grub_le_to_cpu64 (*((volatile grub_uint64_t *) (port->mmio.base + (reg << 3))));
}
}
return grub_inb (port->port + reg);
}
static void
ns8250_reg_write (struct grub_serial_port *port, grub_uint8_t value, grub_addr_t reg)
{
asm volatile("" : : : "memory");
if (port->use_mmio == true)
{
switch(port->mmio.access_size)
{
default:
/* ACPI tables occasionally uses "0" (legacy) as equivalent to "1" (byte). */
case 1:
*((volatile grub_uint8_t *) (port->mmio.base + reg)) = value;
break;
case 2:
*((volatile grub_uint16_t *) (port->mmio.base + (reg << 1))) = grub_cpu_to_le16 (value);
break;
case 3:
*((volatile grub_uint32_t *) (port->mmio.base + (reg << 2))) = grub_cpu_to_le32 (value);
break;
case 4:
/* See commment in ns8250_reg_read(). */
*((volatile grub_uint64_t *) (port->mmio.base + (reg << 3))) = grub_cpu_to_le64 (value);
break;
}
}
else
grub_outb (value, port->port + reg);
}
/* Convert speed to divisor. */
static unsigned short
serial_get_divisor (const struct grub_serial_port *port __attribute__ ((unused)),
const struct grub_serial_config *config)
{
grub_uint32_t base_clock;
grub_uint32_t divisor;
grub_uint32_t actual_speed, error;
/* Get the UART input clock frequency. */
base_clock = config->base_clock ? config->base_clock : UART_DEFAULT_BASE_CLOCK;
/*
* The UART uses 16 times oversampling for the BRG, so adjust the value
* accordingly to calculate the divisor.
*/
base_clock >>= 4;
divisor = (base_clock + (config->speed / 2)) / config->speed;
if (config->speed == 0)
return 0;
if (divisor > 0xffff || divisor == 0)
return 0;
actual_speed = base_clock / divisor;
error = actual_speed > config->speed ? (actual_speed - config->speed)
: (config->speed - actual_speed);
if (error > (config->speed / 30 + 1))
return 0;
return divisor;
}
static void
do_real_config (struct grub_serial_port *port)
{
int divisor;
unsigned char status = 0;
grub_uint64_t endtime;
const unsigned char parities[] = {
[GRUB_SERIAL_PARITY_NONE] = UART_NO_PARITY,
[GRUB_SERIAL_PARITY_ODD] = UART_ODD_PARITY,
[GRUB_SERIAL_PARITY_EVEN] = UART_EVEN_PARITY
};
const unsigned char stop_bits[] = {
[GRUB_SERIAL_STOP_BITS_1] = UART_1_STOP_BIT,
[GRUB_SERIAL_STOP_BITS_2] = UART_2_STOP_BITS,
};
if (port->configured)
return;
port->broken = 0;
divisor = serial_get_divisor (port, &port->config);
/* Turn off the interrupt. */
ns8250_reg_write (port, 0, UART_IER);
/* Set DLAB. */
ns8250_reg_write (port, UART_DLAB, UART_LCR);
ns8250_reg_write (port, divisor & 0xFF, UART_DLL);
ns8250_reg_write (port, divisor >> 8, UART_DLH);
/* Set the line status. */
status |= (parities[port->config.parity]
| (port->config.word_len - 5)
| stop_bits[port->config.stop_bits]);
ns8250_reg_write (port, status, UART_LCR);
if (port->config.rtscts)
{
/* Enable the FIFO. */
ns8250_reg_write (port, UART_ENABLE_FIFO_TRIGGER1, UART_FCR);
/* Turn on DTR and RTS. */
ns8250_reg_write (port, UART_ENABLE_DTRRTS, UART_MCR);
}
else
{
/* Enable the FIFO. */
ns8250_reg_write (port, UART_ENABLE_FIFO_TRIGGER14, UART_FCR);
/* Turn on DTR, RTS, and OUT2. */
ns8250_reg_write (port, UART_ENABLE_DTRRTS | UART_ENABLE_OUT2, UART_MCR);
}
/* Drain the input buffer. */
endtime = grub_get_time_ms () + 1000;
while (ns8250_reg_read (port, UART_LSR) & UART_DATA_READY)
{
ns8250_reg_read (port, UART_RX);
if (grub_get_time_ms () > endtime)
{
port->broken = 1;
break;
}
}
port->configured = 1;
}
/* Fetch a key. */
static int
serial_hw_fetch (struct grub_serial_port *port)
{
do_real_config (port);
if (ns8250_reg_read (port, UART_LSR) & UART_DATA_READY)
return ns8250_reg_read (port, UART_RX);
return -1;
}
/* Put a character. */
static void
serial_hw_put (struct grub_serial_port *port, const int c)
{
grub_uint64_t endtime;
do_real_config (port);
if (port->broken > 5)
endtime = grub_get_time_ms ();
else if (port->broken > 1)
endtime = grub_get_time_ms () + 50;
else
endtime = grub_get_time_ms () + 200;
/* Wait until the transmitter holding register is empty. */
while ((ns8250_reg_read (port, UART_LSR) & UART_EMPTY_TRANSMITTER) == 0)
{
if (grub_get_time_ms () > endtime)
{
port->broken++;
/* There is something wrong. But what can I do? */
return;
}
}
if (port->broken)
port->broken--;
ns8250_reg_write (port, c, UART_TX);
}
/* Initialize a serial device. PORT is the port number for a serial device.
SPEED is a DTE-DTE speed which must be one of these: 2400, 4800, 9600,
19200, 38400, 57600 and 115200. WORD_LEN is the word length to be used
for the device. Likewise, PARITY is the type of the parity and
STOP_BIT_LEN is the length of the stop bit. The possible values for
WORD_LEN, PARITY and STOP_BIT_LEN are defined in the header file as
macros. */
static grub_err_t
serial_hw_configure (struct grub_serial_port *port,
struct grub_serial_config *config)
{
unsigned short divisor;
divisor = serial_get_divisor (port, config);
if (divisor == 0)
return grub_error (GRUB_ERR_BAD_ARGUMENT,
N_("unsupported serial port speed"));
if (config->parity != GRUB_SERIAL_PARITY_NONE
&& config->parity != GRUB_SERIAL_PARITY_ODD
&& config->parity != GRUB_SERIAL_PARITY_EVEN)
return grub_error (GRUB_ERR_BAD_ARGUMENT,
N_("unsupported serial port parity"));
if (config->stop_bits != GRUB_SERIAL_STOP_BITS_1
&& config->stop_bits != GRUB_SERIAL_STOP_BITS_2)
return grub_error (GRUB_ERR_BAD_ARGUMENT,
N_("unsupported serial port stop bits number"));
if (config->word_len < 5 || config->word_len > 8)
return grub_error (GRUB_ERR_BAD_ARGUMENT,
N_("unsupported serial port word length"));
port->config = *config;
port->configured = 0;
/* FIXME: should check if the serial terminal was found. */
return GRUB_ERR_NONE;
}
struct grub_serial_driver grub_ns8250_driver =
{
.configure = serial_hw_configure,
.fetch = serial_hw_fetch,
.put = serial_hw_put
};
static char com_names[GRUB_SERIAL_PORT_NUM][20];
static struct grub_serial_port com_ports[GRUB_SERIAL_PORT_NUM];
void
grub_ns8250_init (void)
{
#ifdef GRUB_MACHINE_PCBIOS
const unsigned short *serial_hw_io_addr = (const unsigned short *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR);
#endif
unsigned i;
for (i = 0; i < GRUB_SERIAL_PORT_NUM; i++)
if (serial_hw_io_addr[i])
{
grub_err_t err;
grub_outb (0x5a, serial_hw_io_addr[i] + UART_SR);
if (grub_inb (serial_hw_io_addr[i] + UART_SR) != 0x5a)
{
dead_ports |= (1 << i);
continue;
}
grub_outb (0xa5, serial_hw_io_addr[i] + UART_SR);
if (grub_inb (serial_hw_io_addr[i] + UART_SR) != 0xa5)
{
dead_ports |= (1 << i);
continue;
}
grub_snprintf (com_names[i], sizeof (com_names[i]), "com%d", i);
com_ports[i].name = com_names[i];
com_ports[i].driver = &grub_ns8250_driver;
com_ports[i].port = serial_hw_io_addr[i];
com_ports[i].use_mmio = false;
err = grub_serial_config_defaults (&com_ports[i]);
if (err)
grub_print_error ();
grub_serial_register (&com_ports[i]);
}
}
/* Return the port number for the UNITth serial device. */
grub_port_t
grub_ns8250_hw_get_port (const unsigned int unit)
{
#ifdef GRUB_MACHINE_PCBIOS
const unsigned short *serial_hw_io_addr = (const unsigned short *) grub_absolute_pointer (GRUB_MEMORY_MACHINE_BIOS_DATA_AREA_ADDR);
#endif
if (unit < GRUB_SERIAL_PORT_NUM
&& !(dead_ports & (1 << unit)))
return serial_hw_io_addr[unit];
else
return 0;
}
struct grub_serial_port *
grub_serial_ns8250_add_port (grub_port_t port, struct grub_serial_config *config)
{
struct grub_serial_port *p;
unsigned i;
for (i = 0; i < GRUB_SERIAL_PORT_NUM; i++)
if (com_ports[i].port == port)
{
if (dead_ports & (1 << i))
return NULL;
/* Give the opportunity for SPCR to configure a default com port. */
if (config != NULL)
grub_serial_port_configure (&com_ports[i], config);
return &com_ports[i];
}
FOR_SERIAL_PORTS (p)
if (p->use_mmio == false && p->port == port)
{
if (config != NULL)
grub_serial_port_configure (p, config);
return p;
}
grub_outb (0x5a, port + UART_SR);
if (grub_inb (port + UART_SR) != 0x5a)
return NULL;
grub_outb (0xa5, port + UART_SR);
if (grub_inb (port + UART_SR) != 0xa5)
return NULL;
p = grub_malloc (sizeof (*p));
if (p == NULL)
return NULL;
p->name = grub_xasprintf ("port%lx", (unsigned long) port);
if (p->name == NULL)
{
grub_free (p);
return NULL;
}
p->driver = &grub_ns8250_driver;
p->use_mmio = false;
p->port = port;
if (config != NULL)
grub_serial_port_configure (p, config);
else
grub_serial_config_defaults (p);
grub_serial_register (p);
return p;
}
struct grub_serial_port *
grub_serial_ns8250_add_mmio (grub_addr_t addr, unsigned int acc_size,
struct grub_serial_config *config)
{
struct grub_serial_port *p;
unsigned i;
for (i = 0; i < GRUB_SERIAL_PORT_NUM; i++)
if (com_ports[i].use_mmio == true && com_ports[i].mmio.base == addr)
{
if (config != NULL)
grub_serial_port_configure (&com_ports[i], config);
return &com_ports[i];
}
FOR_SERIAL_PORTS (p)
if (p->use_mmio == true && p->mmio.base == addr)
{
if (config != NULL)
grub_serial_port_configure (p, config);
return p;
}
p = grub_malloc (sizeof (*p));
if (p == NULL)
return NULL;
p->name = grub_xasprintf ("mmio,%llx", (unsigned long long) addr);
if (p->name == NULL)
{
grub_free (p);
return NULL;
}
p->driver = &grub_ns8250_driver;
p->use_mmio = true;
p->mmio.base = addr;
p->mmio.access_size = acc_size;
if (config != NULL)
grub_serial_port_configure (p, config);
else
grub_serial_config_defaults (p);
grub_serial_register (p);
return p;
}
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