Re: [PATCH] term/serial: Add support for PCI serial devices

[Glenn Washburn]

On Thu, 25 Aug 2022 10:10:45 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> 
> 
> How's this then? seems to build. If this looks allright, I'll post it as
> v2 I suppose.

Yes, this is what I was thinking, with the nice addition of
GRUB_HAS_PCI, which I wasn't considering.

> 
> ---
> diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
> index 5212dfab1369..c0683da2353b 100644
> --- a/grub-core/Makefile.core.def
> +++ b/grub-core/Makefile.core.def
> @@ -224,12 +224,14 @@ kernel = {
>  
>    i386_efi = kern/i386/efi/init.c;
>    i386_efi = bus/pci.c;
> +  i386_efi_cppflags = '-DGRUB_HAS_PCI';

I imagine this should be enabled for all i386 and x86_64 targets, not
just the few that you have here. For instance, what about i386-pc,
which is the 32-bit BIOS target?

>  
>    x86_64 = kern/x86_64/dl.c;
>    x86_64_xen = kern/x86_64/dl.c;
>    x86_64_efi = kern/x86_64/efi/callwrap.S;
>    x86_64_efi = kern/i386/efi/init.c;
>    x86_64_efi = bus/pci.c;
> +  x86_64_efi_cppflags = '-DGRUB_HAS_PCI';
>  
>    xen = kern/i386/tsc.c;
>    xen = kern/i386/xen/tsc.c;
> @@ -271,6 +273,7 @@ kernel = {
>    i386_pc = term/i386/pc/console.c;
>  
>    i386_qemu = bus/pci.c;
> +  i386_qemu_cppflags = '-DGRUB_HAS_PCI';
>    i386_qemu = kern/vga_init.c;
>    i386_qemu = kern/i386/qemu/mmap.c;
>  
> @@ -303,6 +306,7 @@ kernel = {
>    mips_loongson = bus/bonito.c;
>    mips_loongson = bus/cs5536.c;
>    mips_loongson = bus/pci.c;
> +  mips_loongson_cppflags = '-DGRUB_HAS_PCI';
>    mips_loongson = kern/mips/loongson/init.c;
>    mips_loongson = term/at_keyboard.c;
>    mips_loongson = term/ps2.c;
> @@ -2047,6 +2051,8 @@ module = {
>    ieee1275 = term/ieee1275/serial.c;
>    mips_arc = term/arc/serial.c;
>    efi = term/efi/serial.c;
> +  x86 = term/pci/serial.c;
> +  mips_loongson = term/pci/serial.c;
>  
>    enable = terminfomodule;
>    enable = ieee1275;
> diff --git a/grub-core/term/pci/serial.c b/grub-core/term/pci/serial.c
> new file mode 100644
> index 000000000000..581d0760f9f4
> --- /dev/null
> +++ b/grub-core/term/pci/serial.c
> @@ -0,0 +1,83 @@
> +/*
> + *  GRUB  --  GRand Unified Bootloader
> + *  Copyright (C) 2000,2001,2002,2003,2004,2005,2007,2008,2009,2010  Free 
> Software Foundation, Inc.

s/2000,2001,2002,2003,2004,2005,2007,2008,2009,2010/2022/

> + *
> + *  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/term.h>
> +#include <grub/types.h>
> +#include <grub/pci.h>
> +#include <grub/mm.h>
> +#include <grub/misc.h>
> +
> +static int
> +find_pciserial (grub_pci_device_t dev, grub_pci_id_t pciid, void *data)
> +{
> +  grub_pci_address_t cmd_addr, class_addr, bar_addr;
> +  struct grub_serial_port *port;
> +  grub_uint32_t class, bar;
> +  grub_uint16_t cmdreg;
> +  int *nr = data;

I'd prefer a more descriptive name, like port_num.

> +  int err;

s/int/grub_err_t/

> +
> +  (void)pciid;
> +
> +  cmd_addr = grub_pci_make_address (dev, GRUB_PCI_REG_COMMAND);
> +  cmdreg = grub_pci_read (cmd_addr);
> +
> +  class_addr = grub_pci_make_address (dev, GRUB_PCI_REG_REVISION);
> +  class = grub_pci_read (class_addr);
> +
> +  bar_addr = grub_pci_make_address (dev, GRUB_PCI_REG_ADDRESS_REG0);
> +  bar = grub_pci_read (bar_addr);
> +
> +  /* 16550 compattible MODEM or SERIAL */
> +  if (((class >> 16) != GRUB_PCI_CLASS_COMMUNICATION_MODEM &&
> +       (class >> 16) != GRUB_PCI_CLASS_COMMUNICATION_SERIAL) ||
> +      ((class >> 8) & 0xff) != GRUB_PCI_SERIAL_16550_COMPATIBLE)
> +    return 0;
> +
> +  if ((bar & GRUB_PCI_ADDR_SPACE_MASK) != GRUB_PCI_ADDR_SPACE_IO)
> +    return 0;
> +
> +  port = grub_zalloc (sizeof (*port));
> +  if (!port)

Daniel prefers: port != NULL

> +    return 0;
> +
> +  grub_pci_write (cmd_addr, cmdreg | GRUB_PCI_COMMAND_IO_ENABLED);
> +
> +  port->name = grub_xasprintf ("pci%d", (*nr)++);

Incrementing nr should happen just before the return on the success
path.

I believe there will be a memory leak when removing the serial module.
And I'm noticing that there appears to be a memory leak in the efi
serial code also. So maybe this is acceptable.

There should probably be code like:

  if (port->name == NULL)
    goto error;

> +  port->driver = &grub_ns8250_driver;
> +  port->port = bar & GRUB_PCI_ADDR_IO_MASK;
> +  err = grub_serial_config_defaults (port);
> +  if (err)

  if (err != GRUB_ERR_NONE)

> +    {
> +      grub_print_error ();
> +      return 0;

  goto error;

> +    }
> +
> +  grub_serial_register (port);

  err = grub_serial_register (port);
  if (err != GRUB_ERR_NONE)
    goto error;

  (*port_num)++;

> +
> +  return 0;

 error:
   grub_free (port->name);
   grub_free (port);
   return 0;

> +}
> +
> +void
> +grub_pciserial_init (void)
> +{
> +  int nr = 0;

Let's rename this also.

> +
> +  grub_pci_iterate (find_pciserial, &nr);
> +}
> diff --git a/grub-core/term/serial.c b/grub-core/term/serial.c
> index 842322b1c607..09c9e1cd1fdc 100644
> --- a/grub-core/term/serial.c
> +++ b/grub-core/term/serial.c
> @@ -448,6 +448,9 @@ GRUB_MOD_INIT(serial)
>  #ifdef GRUB_MACHINE_ARC
>    grub_arcserial_init ();
>  #endif
> +#ifdef GRUB_HAS_PCI
> +  grub_pciserial_init ();
> +#endif
>  }
>  
>  GRUB_MOD_FINI(serial)
> diff --git a/include/grub/pci.h b/include/grub/pci.h
> index 262c89b748bb..b228bb1b71fd 100644
> --- a/include/grub/pci.h
> +++ b/include/grub/pci.h
> @@ -80,8 +80,13 @@
>  
>  #define  GRUB_PCI_STATUS_DEVSEL_TIMING_SHIFT 9
>  #define  GRUB_PCI_STATUS_DEVSEL_TIMING_MASK 0x0600
> +
>  #define  GRUB_PCI_CLASS_SUBCLASS_VGA  0x0300
>  #define  GRUB_PCI_CLASS_SUBCLASS_USB  0x0c03
> +#define  GRUB_PCI_CLASS_COMMUNICATION_SERIAL  0x0700
> +#define  GRUB_PCI_CLASS_COMMUNICATION_MODEM   0x0703
> +
> +#define  GRUB_PCI_SERIAL_16550_COMPATIBLE 0x02
>  
>  #ifndef ASM_FILE
>  
> diff --git a/include/grub/serial.h b/include/grub/serial.h
> index 67379de45dd1..c57aed19ff2b 100644
> --- a/include/grub/serial.h
> +++ b/include/grub/serial.h
> @@ -193,6 +193,8 @@ const char *
>  grub_arcserial_add_port (const char *path);
>  #endif
>  
> +void grub_pciserial_init (void);

I think this should be wrapped in "#ifdef GRUB_HAS_PCI" for clarity of
use.

Glenn

> +
>  struct grub_serial_port *grub_serial_find (const char *name);
>  extern struct grub_serial_driver grub_ns8250_driver;
>  void EXPORT_FUNC(grub_serial_unregister_driver) (struct grub_serial_driver 
> *driver);