1 files changed, 229 insertions, 0 deletions
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
new file mode 100644
index 0000000000..cd36a97b0e
--- /dev/null
+++ b/drivers/acpi/spcr.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012, Intel Corporation
+ * Copyright (c) 2015, Red Hat, Inc.
+ * Copyright (c) 2015, 2016 Linaro Ltd.
+ */
+
+#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
+ * acpi_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, similar 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)
+{
+	bool xgene_8250 = false;
+
+	if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
+		return false;
+
+	if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE) &&
+	    memcmp(tb->header.oem_id, "HPE   ", ACPI_OEM_ID_SIZE))
+		return false;
+
+	if (!memcmp(tb->header.oem_table_id, "XGENESPC",
+	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
+		xgene_8250 = true;
+
+	if (!memcmp(tb->header.oem_table_id, "ProLiant",
+	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 1)
+		xgene_8250 = true;
+
+	return xgene_8250;
+}
+
+/**
+ * acpi_parse_spcr() - parse ACPI SPCR table and add preferred console
+ * @enable_earlycon: set up earlycon for the console specified by the table
+ * @enable_console: setup 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 @enable_earlycon is true, earlycon is set up.
+ * If @enable_console is true the system console is also configured.
+ *
+ * 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 acpi_parse_spcr(bool enable_earlycon, bool enable_console)
+{
+	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)
+		pr_info("SPCR table version %d\n", table->header.revision);
+
+	if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+		u32 bit_width = table->serial_port.access_width;
+
+		if (bit_width > ACPI_ACCESS_BIT_MAX) {
+			pr_err(FW_BUG "Unacceptable wide SPCR Access Width. Defaulting to byte size\n");
+			bit_width = ACPI_ACCESS_BIT_DEFAULT;
+		}
+		switch (ACPI_ACCESS_BIT_WIDTH((bit_width))) {
+		default:
+			pr_err(FW_BUG "Unexpected SPCR Access Width. Defaulting to byte size\n");
+			fallthrough;
+		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";
+		fallthrough;
+	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:
+	case ACPI_DBG2_16550_WITH_GAS:
+	case ACPI_DBG2_16550_NVIDIA:
+		uart = "uart";
+		break;
+	default:
+		err = -ENOENT;
+		goto done;
+	}
+
+	switch (table->baud_rate) {
+	case 0:
+		/*
+		 * SPCR 1.04 defines 0 as a preconfigured state of UART.
+		 * Assume firmware or bootloader configures console correctly.
+		 */
+		baud_rate = 0;
+		break;
+	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 (enable_earlycon)
+			uart = "qdf2400_e44";
+	}
+
+	if (xgene_8250_erratum_present(table)) {
+		iotype = "mmio32";
+
+		/*
+		 * For xgene v1 and v2 we don't know the clock rate of the
+		 * UART so don't attempt to change to the baud rate state
+		 * in the table because driver cannot calculate the dividers
+		 */
+		baud_rate = 0;
+	}
+
+	if (!baud_rate) {
+		snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
+			 table->serial_port.address);
+	} else {
+		snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
+			 table->serial_port.address, baud_rate);
+	}
+
+	pr_info("console: %s\n", opts);
+
+	if (enable_earlycon)
+		setup_earlycon(opts);
+
+	if (enable_console)
+		err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
+	else
+		err = 0;
+done:
+	acpi_put_table((struct acpi_table_header *)table);
+	return err;
+}