7b192ec4cd
"serial auto" is now equivalent to just "serial" and will use the SPCR to discover the port if present, otherwise defaults to "com0" as before. This allows to support MMIO ports specified by ACPI which is needed on AWS EC2 "metal" instances, and will enable GRUB to pickup the port configuration specified by ACPI in other cases. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2022 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#if !defined(GRUB_MACHINE_IEEE1275) && !defined(GRUB_MACHINE_QEMU)
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#include <grub/serial.h>
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#include <grub/ns8250.h>
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#include <grub/types.h>
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#include <grub/dl.h>
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#include <grub/acpi.h>
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char *
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grub_ns8250_spcr_init (void)
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{
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struct grub_acpi_spcr *spcr;
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struct grub_serial_config config;
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spcr = grub_acpi_find_table (GRUB_ACPI_SPCR_SIGNATURE);
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if (spcr == NULL)
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return NULL;
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if (spcr->hdr.revision < 2)
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return NULL;
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if (spcr->intf_type != GRUB_ACPI_SPCR_INTF_TYPE_16550 &&
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spcr->intf_type != GRUB_ACPI_SPCR_INTF_TYPE_16550X)
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return NULL;
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/* For now, we only support byte accesses. */
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if (spcr->base_addr.access_size != GRUB_ACPI_GENADDR_SIZE_BYTE &&
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spcr->base_addr.access_size != GRUB_ACPI_GENADDR_SIZE_LGCY)
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return NULL;
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config.word_len = 8;
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config.parity = GRUB_SERIAL_PARITY_NONE;
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config.stop_bits = GRUB_SERIAL_STOP_BITS_1;
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config.base_clock = UART_DEFAULT_BASE_CLOCK;
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if (spcr->flow_control & GRUB_ACPI_SPCR_FC_RTSCTS)
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config.rtscts = 1;
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else
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config.rtscts = 0;
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switch (spcr->baud_rate)
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{
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case GRUB_ACPI_SPCR_BAUD_9600:
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config.speed = 9600;
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break;
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case GRUB_ACPI_SPCR_BAUD_19200:
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config.speed = 19200;
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break;
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case GRUB_ACPI_SPCR_BAUD_57600:
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config.speed = 57600;
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break;
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case GRUB_ACPI_SPCR_BAUD_115200:
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config.speed = 115200;
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break;
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case GRUB_ACPI_SPCR_BAUD_CURRENT:
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default:
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/*
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* We don't (yet) have a way to read the currently
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* configured speed in HW, so let's use a sane default.
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*/
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config.speed = 115200;
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break;
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};
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switch (spcr->base_addr.space_id)
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{
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case GRUB_ACPI_GENADDR_MEM_SPACE:
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return grub_serial_ns8250_add_mmio (spcr->base_addr.addr, &config);
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case GRUB_ACPI_GENADDR_IO_SPACE:
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return grub_serial_ns8250_add_port (spcr->base_addr.addr, &config);
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default:
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return NULL;
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};
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}
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#endif
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