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uart: DBG2 support to find the debug uart

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The Debug Port Table 2 (DBG2) contains information on which devices
can be used for debugging purposes.

Add support to the uart driver to use the DBG2 table when enabled from
loader.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D44359
This commit is contained in:
Andrew Turner 2024-03-12 18:15:29 +00:00
parent d316de24fa
commit 097bd33dd7
1 changed files with 83 additions and 0 deletions
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83
sys/dev/uart/uart_cpu_acpi.c
View file

@ -210,12 +210,95 @@ uart_cpu_acpi_spcr(int devtype, struct uart_devinfo *di)
return (error);
}
static int
uart_cpu_acpi_dbg2(struct uart_devinfo *di)
{
vm_paddr_t dbg2_physaddr;
ACPI_TABLE_DBG2 *dbg2;
ACPI_DBG2_DEVICE *dbg2_dev;
ACPI_GENERIC_ADDRESS *base_address;
struct acpi_uart_compat_data *cd;
struct uart_class *class;
int error;
bool found;
/* Look for the SPCR table. */
dbg2_physaddr = acpi_find_table(ACPI_SIG_DBG2);
if (dbg2_physaddr == 0)
return (ENXIO);
dbg2 = acpi_map_table(dbg2_physaddr, ACPI_SIG_DBG2);
if (dbg2 == NULL) {
printf("Unable to map the DBG2 table!\n");
return (ENXIO);
}
error = ENXIO;
dbg2_dev = (ACPI_DBG2_DEVICE *)((vm_offset_t)dbg2 + dbg2->InfoOffset);
found = false;
while ((vm_offset_t)dbg2_dev + dbg2_dev->Length <=
(vm_offset_t)dbg2 + dbg2->Header.Length) {
if (dbg2_dev->PortType != ACPI_DBG2_SERIAL_PORT)
goto next;
/* XXX: Too restrictive? */
if (dbg2_dev->RegisterCount != 1)
goto next;
cd = uart_cpu_acpi_scan(dbg2_dev->PortSubtype);
if (cd == NULL)
goto next;
class = cd->cd_class;
base_address = (ACPI_GENERIC_ADDRESS *)
((vm_offset_t)dbg2_dev + dbg2_dev->BaseAddressOffset);
error = uart_cpu_acpi_init_devinfo(di, class, base_address);
if (error == 0) {
found = true;
break;
}
next:
dbg2_dev = (ACPI_DBG2_DEVICE *)
((vm_offset_t)dbg2_dev + dbg2_dev->Length);
}
if (!found)
goto out;
/* XXX: Find the correct value */
di->baudrate = 115200;
/* Apply device tweaks. */
if ((cd->cd_quirks & UART_F_IGNORE_SPCR_REGSHFT) ==
UART_F_IGNORE_SPCR_REGSHFT) {
di->bas.regshft = cd->cd_regshft;
}
/* Create a bus space handle. */
error = bus_space_map(di->bas.bst, base_address->Address,
uart_getrange(class), 0, &di->bas.bsh);
out:
acpi_unmap_table(dbg2);
return (error);
}
int
uart_cpu_acpi_setup(int devtype, struct uart_devinfo *di)
{
char *cp;
switch(devtype) {
case UART_DEV_CONSOLE:
return (uart_cpu_acpi_spcr(devtype, di));
case UART_DEV_DBGPORT:
/* Use the Debug Port Table 2 (DBG2) to find a debug uart */
cp = kern_getenv("hw.acpi.enable_dbg2");
if (cp != NULL && strcasecmp(cp, "yes") == 0)
return (uart_cpu_acpi_dbg2(di));
break;
}
return (ENXIO);
}