diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/acpi/spcr.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c new file mode 100644 index 000000000..c336784d0 --- /dev/null +++ b/drivers/acpi/spcr.c @@ -0,0 +1,229 @@ +/* + * 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 + * 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, 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) +{ + 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) { + switch (ACPI_ACCESS_BIT_WIDTH(( + table->serial_port.access_width))) { + default: + pr_err("Unexpected SPCR Access Width. Defaulting to byte size\n"); + /* fall through */ + 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 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; +} |