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Support --base-clock for serial command to handle weird cards with

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non-standard base clock.
This commit is contained in:
Vladimir Serbinenko 2013-11-01 19:33:22 +01:00
parent eb03ede014
commit 89295a0628
4 changed files with 64 additions and 48 deletions
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53
grub-core/term/ns8250.c
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@ -38,46 +38,33 @@ static const grub_port_t serial_hw_io_addr[] = GRUB_MACHINE_SERIAL_PORTS;
static int dead_ports = 0;
#ifdef GRUB_MACHINE_MIPS_LOONGSON
#define DEFAULT_BASE_CLOCK (2 * 115200)
#else
#define DEFAULT_BASE_CLOCK 115200
#endif
/* Convert speed to divisor. */
static unsigned short
serial_get_divisor (const struct grub_serial_port *port __attribute__ ((unused)),
const struct grub_serial_config *config)
{
unsigned int i;
grub_uint32_t base_clock;
grub_uint32_t divisor;
grub_uint32_t actual_speed, error;
/* The structure for speed vs. divisor. */
struct divisor
{
unsigned int speed;
unsigned short div;
};
base_clock = config->base_clock ? (config->base_clock >> 4) : DEFAULT_BASE_CLOCK;
/* The table which lists common configurations. */
/* 1843200 / (speed * 16) */
static struct divisor divisor_tab[] =
{
{ 2400, 0x0030 },
{ 4800, 0x0018 },
{ 9600, 0x000C },
{ 19200, 0x0006 },
{ 38400, 0x0003 },
{ 57600, 0x0002 },
{ 115200, 0x0001 }
};
/* Set the baud rate. */
for (i = 0; i < ARRAY_SIZE (divisor_tab); i++)
if (divisor_tab[i].speed == config->speed)
{
/* internal Loongson UART runs twice the usual rate. */
#ifdef GRUB_MACHINE_MIPS_LOONGSON
if (port->port == 0xbff003f8)
return 2 * divisor_tab[i].div;
else
#endif
return divisor_tab[i].div;
}
return 0;
divisor = (base_clock + (config->speed / 2)) / config->speed;
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