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/*
* Copyright (c) 2012, Intel Corporation
* Copyright (c) 2015, Red Hat, Inc.
* Copyright (c) 2015, 2016 Linaro Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) "ACPI: SPCR: " fmt
#include <linux/acpi.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/serial_core.h>
/*
* Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
* occasionally getting stuck as 1. To avoid the potential for a hang, check
* TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
* implementations, so only do so if an affected platform is detected in
* parse_spcr().
*/
bool qdf2400_e44_present;
EXPORT_SYMBOL(qdf2400_e44_present);
/*
* Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
* Detect them by examining the OEM fields in the SPCR header, similiar to PCI
* quirk detection in pci_mcfg.c.
*/
static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
{
if (memcmp(h->oem_id, "QCOM ", ACPI_OEM_ID_SIZE))
return false;
if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
return true;
if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
h->oem_revision == 1)
return true;
return false;
}
/*
* APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
* register aligned to 32-bit. In addition, the BIOS also encoded the
* access width to be 8 bits. This function detects this errata condition.
*/
static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
{
if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
return false;
if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE))
return false;
if (!memcmp(tb->header.oem_table_id, "XGENESPC",
ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
return true;
return false;
}
/**
* parse_spcr() - parse ACPI SPCR table and add preferred console
*
* @earlycon: set up earlycon for the console specified by the table
*
* For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
* defined to parse ACPI SPCR table. As a result of the parsing preferred
* console is registered and if @earlycon is true, earlycon is set up.
*
* When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
* from arch initialization code as soon as the DT/ACPI decision is made.
*
*/
int __init parse_spcr(bool earlycon)
{
static char opts[64];
struct acpi_table_spcr *table;
acpi_status status;
char *uart;
char *iotype;
int baud_rate;
int err;
if (acpi_disabled)
return -ENODEV;
status = acpi_get_table(ACPI_SIG_SPCR, 0,
(struct acpi_table_header **)&table);
if (ACPI_FAILURE(status))
return -ENOENT;
if (table->header.revision < 2) {
err = -ENOENT;
pr_err("wrong table version\n");
goto done;
}
if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
switch (ACPI_ACCESS_BIT_WIDTH((
table->serial_port.access_width))) {
default:
pr_err("Unexpected SPCR Access Width. Defaulting to byte size\n");
case 8:
iotype = "mmio";
break;
case 16:
iotype = "mmio16";
break;
case 32:
iotype = "mmio32";
break;
}
} else
iotype = "io";
switch (table->interface_type) {
case ACPI_DBG2_ARM_SBSA_32BIT:
iotype = "mmio32";
/* fall through */
case ACPI_DBG2_ARM_PL011:
case ACPI_DBG2_ARM_SBSA_GENERIC:
case ACPI_DBG2_BCM2835:
uart = "pl011";
break;
case ACPI_DBG2_16550_COMPATIBLE:
case ACPI_DBG2_16550_SUBSET:
uart = "uart";
break;
default:
err = -ENOENT;
goto done;
}
switch (table->baud_rate) {
case 3:
baud_rate = 9600;
break;
case 4:
baud_rate = 19200;
break;
case 6:
baud_rate = 57600;
break;
case 7:
baud_rate = 115200;
break;
default:
err = -ENOENT;
goto done;
}
/*
* If the E44 erratum is required, then we need to tell the pl011
* driver to implement the work-around.
*
* The global variable is used by the probe function when it
* creates the UARTs, whether or not they're used as a console.
*
* If the user specifies "traditional" earlycon, the qdf2400_e44
* console name matches the EARLYCON_DECLARE() statement, and
* SPCR is not used. Parameter "earlycon" is false.
*
* If the user specifies "SPCR" earlycon, then we need to update
* the console name so that it also says "qdf2400_e44". Parameter
* "earlycon" is true.
*
* For consistency, if we change the console name, then we do it
* for everyone, not just earlycon.
*/
if (qdf2400_erratum_44_present(&table->header)) {
qdf2400_e44_present = true;
if (earlycon)
uart = "qdf2400_e44";
}
if (xgene_8250_erratum_present(table))
iotype = "mmio32";
snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
table->serial_port.address, baud_rate);
pr_info("console: %s\n", opts);
if (earlycon)
setup_earlycon(opts);
err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
done:
acpi_put_table((struct acpi_table_header *)table);
return err;
}
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