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term/serial: Add ability to specify MMIO ports via "serial" command

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This adds the ability to explicitly add an MMIO based serial port
via the "serial" command. The syntax is:

  serial --port=mmio,<hex_address>{.b,.w,.l,.q}

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Benjamin Herrenschmidt 2022-12-23 12:47:59 +11:00 committed by Daniel Kiper
parent f5e1d23a18
commit c4e8016316
2 changed files with 93 additions and 4 deletions
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26
docs/grub.texi
View File

@ -4168,8 +4168,24 @@ Commands usable anywhere in the menu and in the command-line.
@deffn Command serial [@option{--unit=unit}] [@option{--port=port}] [@option{--speed=speed}] [@option{--word=word}] [@option{--parity=parity}] [@option{--stop=stop}]
Initialize a serial device. @var{unit} is a number in the range 0-3
specifying which serial port to use; default is 0, which corresponds to
the port often called COM1. @var{port} is the I/O port where the UART
is to be found; if specified it takes precedence over @var{unit}.
the port often called COM1.
@var{port} is the I/O port where the UART is to be found or, if prefixed
with @samp{mmio,}, the MMIO address of the UART. If specified it takes
precedence over @var{unit}.
Additionally, an MMIO address can be suffixed with:
@itemize @bullet
@item
@samp{.b} for bytes access (default)
@item
@samp{.w} for 16-bit word access
@item
@samp{.l} for 32-bit long word access or
@item
@samp{.q} for 64-bit long long word access
@end itemize
@var{speed} is the transmission speed; default is 9600. @var{word} and
@var{stop} are the number of data bits and stop bits. Data bits must
be in the range 5-8 and stop bits must be 1 or 2. Default is 8 data
@ -4185,6 +4201,12 @@ The serial port is not used as a communication channel unless the
@command{terminal_input} or @command{terminal_output} command is used
(@pxref{terminal_input}, @pxref{terminal_output}).
Examples:
@example
serial --port=3f8 --speed=9600
serial --port=mmio,fefb0000.l --speed=115200
@end example
See also @ref{Serial terminal}.
@end deffn

71
grub-core/term/serial.c
View File

@ -164,6 +164,70 @@ grub_serial_find (const char *name)
if (grub_strcmp (port->name, name) == 0)
break;
}
if (!port && grub_strncmp (name, "mmio,", sizeof ("mmio,") - 1) == 0
&& grub_isxdigit (name [sizeof ("mmio,") - 1]))
{
const char *p1, *p = &name[sizeof ("mmio,") - 1];
grub_addr_t addr = grub_strtoul (p, &p1, 16);
unsigned int acc_size = 1;
unsigned int nlen = p1 - p;
/*
* If we reach here, we know there's a digit after "mmio,", so
* all we need to check is the validity of the character following
* the number, which should be a termination, or a dot followed by
* an access size.
*/
if (p1[0] != '\0' && p1[0] != '.')
{
grub_error (GRUB_ERR_BAD_ARGUMENT, N_("incorrect MMIO address syntax"));
return NULL;
}
if (p1[0] == '.')
switch(p1[1])
{
case 'w':
acc_size = 2;
break;
case 'l':
acc_size = 3;
break;
case 'q':
acc_size = 4;
break;
case 'b':
acc_size = 1;
break;
default:
/*
* Should we abort for an unknown size? Let's just default
* to 1 byte, it would increase the chance that the user who
* did a typo can actually see the console.
*/
grub_error (GRUB_ERR_BAD_ARGUMENT, N_("incorrect MMIO access size"));
}
/*
* Specifying the access size is optional an grub_serial_ns8250_add_mmio()
* will not add it to the name. So the original loop trying to match an
* existing port above might have missed this one. Let's do another
* search ignoring the access size part of the string. At this point
* nlen contains the length of the name up to the end of the address.
*/
FOR_SERIAL_PORTS (port)
if (grub_strncmp (port->name, name, nlen) == 0) {
break;
}
name = grub_serial_ns8250_add_mmio (addr, acc_size, NULL);
if (name == NULL)
return NULL;
FOR_SERIAL_PORTS (port)
if (grub_strcmp (port->name, name) == 0) {
break;
}
}
#if (defined(__i386__) || defined(__x86_64__)) && !defined(GRUB_MACHINE_IEEE1275) && !defined(GRUB_MACHINE_QEMU)
if (!port && grub_strcmp (name, "auto") == 0)
@ -215,8 +279,11 @@ grub_cmd_serial (grub_extcmd_context_t ctxt, int argc, char **args)
if (state[OPTION_PORT].set)
{
grub_snprintf (pname, sizeof (pname), "port%lx",
grub_strtoul (state[1].arg, 0, 0));
if (grub_strncmp (state[OPTION_PORT].arg, "mmio,", sizeof ("mmio,") - 1) == 0)
grub_snprintf (pname, sizeof (pname), "%s", state[1].arg);
else
grub_snprintf (pname, sizeof (pname), "port%lx",
grub_strtoul (state[1].arg, 0, 0));
name = pname;
}