1 /* 2 * Copyright (c) 2012, Intel Corporation 3 * Copyright (c) 2015, Red Hat, Inc. 4 * Copyright (c) 2015, 2016 Linaro Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 */ 11 12 #define pr_fmt(fmt) "ACPI: SPCR: " fmt 13 14 #include <linux/acpi.h> 15 #include <linux/console.h> 16 #include <linux/kernel.h> 17 #include <linux/serial_core.h> 18 19 /** 20 * parse_spcr() - parse ACPI SPCR table and add preferred console 21 * 22 * @earlycon: set up earlycon for the console specified by the table 23 * 24 * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be 25 * defined to parse ACPI SPCR table. As a result of the parsing preferred 26 * console is registered and if @earlycon is true, earlycon is set up. 27 * 28 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called 29 * from arch inintialization code as soon as the DT/ACPI decision is made. 30 * 31 */ 32 int __init parse_spcr(bool earlycon) 33 { 34 static char opts[64]; 35 struct acpi_table_spcr *table; 36 acpi_size table_size; 37 acpi_status status; 38 char *uart; 39 char *iotype; 40 int baud_rate; 41 int err; 42 43 if (acpi_disabled) 44 return -ENODEV; 45 46 status = acpi_get_table_with_size(ACPI_SIG_SPCR, 0, 47 (struct acpi_table_header **)&table, 48 &table_size); 49 50 if (ACPI_FAILURE(status)) 51 return -ENOENT; 52 53 if (table->header.revision < 2) { 54 err = -ENOENT; 55 pr_err("wrong table version\n"); 56 goto done; 57 } 58 59 iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ? 60 "mmio" : "io"; 61 62 switch (table->interface_type) { 63 case ACPI_DBG2_ARM_SBSA_32BIT: 64 iotype = "mmio32"; 65 /* fall through */ 66 case ACPI_DBG2_ARM_PL011: 67 case ACPI_DBG2_ARM_SBSA_GENERIC: 68 case ACPI_DBG2_BCM2835: 69 uart = "pl011"; 70 break; 71 case ACPI_DBG2_16550_COMPATIBLE: 72 case ACPI_DBG2_16550_SUBSET: 73 uart = "uart"; 74 break; 75 default: 76 err = -ENOENT; 77 goto done; 78 } 79 80 switch (table->baud_rate) { 81 case 3: 82 baud_rate = 9600; 83 break; 84 case 4: 85 baud_rate = 19200; 86 break; 87 case 6: 88 baud_rate = 57600; 89 break; 90 case 7: 91 baud_rate = 115200; 92 break; 93 default: 94 err = -ENOENT; 95 goto done; 96 } 97 98 snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype, 99 table->serial_port.address, baud_rate); 100 101 pr_info("console: %s\n", opts); 102 103 if (earlycon) 104 setup_earlycon(opts); 105 106 err = add_preferred_console(uart, 0, opts + strlen(uart) + 1); 107 108 done: 109 early_acpi_os_unmap_memory((void __iomem *)table, table_size); 110 return err; 111 } 112