drivers/acpi/spcr.c

   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  * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
  21  * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
  22  * quirk detection in pci_mcfg.c.
  23  */
  24 static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
  25 {
  26         if (memcmp(h->oem_id, "QCOM  ", ACPI_OEM_ID_SIZE))
  27                 return false;
  28
  29         if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
  30                 return true;
  31
  32         if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
  33                         h->oem_revision == 1)
  34                 return true;
  35
  36         return false;
  37 }
  38
  39 /**
  40  * parse_spcr() - parse ACPI SPCR table and add preferred console
  41  *
  42  * @earlycon: set up earlycon for the console specified by the table
  43  *
  44  * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
  45  * defined to parse ACPI SPCR table.  As a result of the parsing preferred
  46  * console is registered and if @earlycon is true, earlycon is set up.
  47  *
  48  * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
  49  * from arch initialization code as soon as the DT/ACPI decision is made.
  50  *
  51  */
  52 int __init parse_spcr(bool earlycon)
  53 {
  54         static char opts[64];
  55         struct acpi_table_spcr *table;
  56         acpi_status status;
  57         char *uart;
  58         char *iotype;
  59         int baud_rate;
  60         int err;
  61
  62         if (acpi_disabled)
  63                 return -ENODEV;
  64
  65         status = acpi_get_table(ACPI_SIG_SPCR, 0,
  66                                 (struct acpi_table_header **)&table);
  67
  68         if (ACPI_FAILURE(status))
  69                 return -ENOENT;
  70
  71         if (table->header.revision < 2) {
  72                 err = -ENOENT;
  73                 pr_err("wrong table version\n");
  74                 goto done;
  75         }
  76
  77         iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
  78                         "mmio" : "io";
  79
  80         switch (table->interface_type) {
  81         case ACPI_DBG2_ARM_SBSA_32BIT:
  82                 iotype = "mmio32";
  83                 /* fall through */
  84         case ACPI_DBG2_ARM_PL011:
  85         case ACPI_DBG2_ARM_SBSA_GENERIC:
  86         case ACPI_DBG2_BCM2835:
  87                 uart = "pl011";
  88                 break;
  89         case ACPI_DBG2_16550_COMPATIBLE:
  90         case ACPI_DBG2_16550_SUBSET:
  91                 uart = "uart";
  92                 break;
  93         default:
  94                 err = -ENOENT;
  95                 goto done;
  96         }
  97
  98         switch (table->baud_rate) {
  99         case 3:
 100                 baud_rate = 9600;
 101                 break;
 102         case 4:
 103                 baud_rate = 19200;
 104                 break;
 105         case 6:
 106                 baud_rate = 57600;
 107                 break;
 108         case 7:
 109                 baud_rate = 115200;
 110                 break;
 111         default:
 112                 err = -ENOENT;
 113                 goto done;
 114         }
 115
 116         if (qdf2400_erratum_44_present(&table->header))
 117                 uart = "qdf2400_e44";
 118
 119         snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
 120                  table->serial_port.address, baud_rate);
 121
 122         pr_info("console: %s\n", opts);
 123
 124         if (earlycon)
 125                 setup_earlycon(opts);
 126
 127         err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
 128
 129 done:
 130         acpi_put_table((struct acpi_table_header *)table);
 131         return err;
 132 }