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// SPDX-License-Identifier: GPL-2.0+
/*
* UART support for U-Boot when launched from Coreboot
*
* Copyright 2019 Google LLC
*/
#define LOG_CATGEGORY UCLASS_SERIAL
#include <common.h>
#include <dm.h>
#include <log.h>
#include <ns16550.h>
#include <serial.h>
#include <acpi/acpi_table.h>
#include <asm/cb_sysinfo.h>
DECLARE_GLOBAL_DATA_PTR;
static int read_dbg2(struct ns16550_plat *plat)
{
struct acpi_table_header *tab;
struct acpi_dbg2_header *hdr;
struct acpi_dbg2_device *dbg;
struct acpi_gen_regaddr *addr;
u32 *addr_size;
log_debug("Looking for DBG2 in ACPI tables\n");
if (!gd->acpi_start) {
log_debug("No ACPI tables\n");
return -ENOENT;
}
tab = acpi_find_table("DBG2");
if (!tab) {
log_debug("No DBG2 table\n");
return -ENOENT;
}
hdr = container_of(tab, struct acpi_dbg2_header, header);
/* We only use the first device, but check that there is at least one */
if (!hdr->devices_count) {
log_debug("No devices\n");
return -ENOENT;
}
if (hdr->devices_offset >= tab->length) {
log_debug("Invalid offset\n");
return -EINVAL;
}
dbg = (void *)hdr + hdr->devices_offset;
if (dbg->revision) {
log_debug("Invalid revision %d\n", dbg->revision);
return -EINVAL;
}
if (!dbg->address_count) {
log_debug("No addresses\n");
return -EINVAL;
}
if (dbg->port_type != ACPI_DBG2_SERIAL_PORT) {
log_debug("Not a serial port\n");
return -EPROTOTYPE;
}
if (dbg->port_subtype != ACPI_DBG2_16550_COMPATIBLE) {
log_debug("Incompatible serial port\n");
return -EPROTOTYPE;
}
if (dbg->base_address_offset >= dbg->length ||
dbg->address_size_offset >= dbg->length) {
log_debug("Invalid base address/size offsets %d, %d\n",
dbg->base_address_offset, dbg->address_size_offset);
return -EINVAL;
}
addr_size = (void *)dbg + dbg->address_size_offset;
if (!*addr_size) {
log_debug("Zero address size\n");
return -EINVAL;
}
addr = (void *)dbg + dbg->base_address_offset;
if (addr->space_id != ACPI_ADDRESS_SPACE_MEMORY) {
log_debug("Incompatible space %d\n", addr->space_id);
return -EPROTOTYPE;
}
plat->base = addr->addrl;
/* ACPI_ACCESS_SIZE_DWORD_ACCESS is 3; we want 2 */
plat->reg_shift = addr->access_size - 1;
plat->reg_width = 4; /* coreboot sets bit_width to 0 */
plat->clock = 1843200;
plat->fcr = UART_FCR_DEFVAL;
plat->flags = 0;
log_debug("Collected UART from ACPI DBG2 table\n");
return 0;
}
static int coreboot_of_to_plat(struct udevice *dev)
{
struct ns16550_plat *plat = dev_get_plat(dev);
struct cb_serial *cb_info = lib_sysinfo.serial;
int ret = -ENOENT;
if (cb_info) {
plat->base = cb_info->baseaddr;
plat->reg_shift = cb_info->regwidth == 4 ? 2 : 0;
plat->reg_width = cb_info->regwidth;
plat->clock = cb_info->input_hertz;
plat->fcr = UART_FCR_DEFVAL;
plat->flags = 0;
if (cb_info->type == CB_SERIAL_TYPE_IO_MAPPED)
plat->flags |= NS16550_FLAG_IO;
ret = 0;
} else if (IS_ENABLED(CONFIG_COREBOOT_SERIAL_FROM_DBG2)) {
ret = read_dbg2(plat);
}
if (ret) {
/*
* Returning an error will cause U-Boot to complain that
* there is no UART, which may panic. So stay silent and
* pray that the video console will work.
*/
log_debug("Cannot detect UART\n");
}
return 0;
}
static const struct udevice_id coreboot_serial_ids[] = {
{ .compatible = "coreboot-serial" },
{ },
};
U_BOOT_DRIVER(coreboot_uart) = {
.name = "coreboot_uart",
.id = UCLASS_SERIAL,
.of_match = coreboot_serial_ids,
.priv_auto = sizeof(struct ns16550),
.plat_auto = sizeof(struct ns16550_plat),
.of_to_plat = coreboot_of_to_plat,
.probe = ns16550_serial_probe,
.ops = &ns16550_serial_ops,
.flags = DM_FLAG_PRE_RELOC,
};
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