Re: [PATCH v2 2/3] term/serial: Add support for PCI serial devices

[Daniel Kiper]

Sorry for late reply...

May I ask you to send the patches using "git send-email"?

On Fri, Aug 26, 2022 at 01:01:44PM +0200, peterz@infradead.org wrote:
> Loosely based on early_pci_serial_init() from Linux, allow GRUB to make
> use of PCI serial devices.
>
> Specifically, my Alderlake NUC exposes the Intel AMT SoL UART as a PCI
> enumerated device but doesn't include it in the EFI tables.
>
> Tested and confirmed working on a "Lenovo P360 Tiny" with Intel AMT
> enabled. This specific machine has (from lspci -vv):
>
> 00:16.3 Serial controller: Intel Corporation Device 7aeb (rev 11) (prog-if 02 
> [16550])
>         DeviceName: Onboard - Other
>         Subsystem: Lenovo Device 330e
>         Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- 
> Stepping- SERR- FastB2B- DisINTx-
>         Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- 
> <TAbort- <MAbort- >SERR- <PERR- INTx-
>         Interrupt: pin D routed to IRQ 19
>         Region 0: I/O ports at 40a0 [size=8]
>         Region 1: Memory at b4224000 (32-bit, non-prefetchable) [size=4K]
>         Capabilities: [40] MSI: Enable- Count=1/1 Maskable- 64bit+
>                 Address: 0000000000000000  Data: 0000
>         Capabilities: [50] Power Management version 3
>                 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA 
> PME(D0-,D1-,D2-,D3hot-,D3cold-)
>                 Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
>         Kernel driver in use: serial
>
> >From which the following config (/etc/default/grub) gets a working
> serial setup:
>
> GRUB_CMDLINE_LINUX="console=tty0 earlyprintk=pciserial,00:16.3,115200 
> console=ttyS0,115200"
> GRUB_SERIAL_COMMAND="serial --port=0x40a0 --speed=115200"

Please add a blurb how to use this driver to the docs/grub.texi file.

> GRUB_TERMINAL="serial console"
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
>
> Index: grub/grub-core/Makefile.core.def
> ===================================================================
> --- grub.orig/grub-core/Makefile.core.def
> +++ grub/grub-core/Makefile.core.def
> @@ -2047,6 +2047,7 @@ module = {
>    ieee1275 = term/ieee1275/serial.c;
>    mips_arc = term/arc/serial.c;
>    efi = term/efi/serial.c;
> +  pci = term/pci/serial.c;

I think this should be "x86 = term/pci/serial.c".

>
>    enable = terminfomodule;
>    enable = ieee1275;
> Index: grub/grub-core/term/pci/serial.c
> ===================================================================
> --- /dev/null
> +++ grub/grub-core/term/pci/serial.c
> @@ -0,0 +1,95 @@
> +/*
> + *  GRUB  --  GRand Unified Bootloader
> + *  Copyright (C) 2022  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/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_id_t pciid __attribute__ ((unused))

> +{
> +  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 *port_num = data;
> +  grub_err_t err;
> +
> +  (void)pciid;

... and please drop this...

> +  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 == NULL)
> +    return 0;
> +
> +  port->name = grub_xasprintf ("pci%d", (*port_num));
> +  if (port->name == NULL)
> +    goto error;
> +
> +  grub_pci_write (cmd_addr, cmdreg | GRUB_PCI_COMMAND_IO_ENABLED);
> +
> +  port->driver = &grub_ns8250_driver;
> +  port->port = bar & GRUB_PCI_ADDR_IO_MASK;
> +  err = grub_serial_config_defaults (port);
> +  if (err != GRUB_ERR_NONE)
> +    {
> +      grub_print_error ();
> +      goto error;
> +    }
> +
> +  err = grub_serial_register (port);
> +  if (err != GRUB_ERR_NONE)
> +    goto error;
> +
> +  (*port_num)++;
> +
> +  return 0;
> +
> +error:

s/error/fail/

And please add a space before label...

> +  grub_free (port->name);
> +  grub_free (port);
> +  return 0;
> +}

Daniel