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  * APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
  41  * register aligned to 32-bit. In addition, the BIOS also encoded the
  42  * access width to be 8 bits. This function detects this errata condition.
  43  */
  44 static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
  45 {
  46         if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
  47                 return false;
  48
  49         if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE))
  50                 return false;
  51
  52         if (!memcmp(tb->header.oem_table_id, "XGENESPC",
  53             ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
  54                 return true;
  55
  56         return false;
  57 }
  58
  59 /**
  60  * parse_spcr() - parse ACPI SPCR table and add preferred console
  61  *
  62  * @earlycon: set up earlycon for the console specified by the table
  63  *
  64  * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
  65  * defined to parse ACPI SPCR table.  As a result of the parsing preferred
  66  * console is registered and if @earlycon is true, earlycon is set up.
  67  *
  68  * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
  69  * from arch initialization code as soon as the DT/ACPI decision is made.
  70  *
  71  */
  72 int __init parse_spcr(bool earlycon)
  73 {
  74         static char opts[64];
  75         struct acpi_table_spcr *table;
  76         acpi_status status;
  77         char *uart;
  78         char *iotype;
  79         int baud_rate;
  80         int err;
  81
  82         if (acpi_disabled)
  83                 return -ENODEV;
  84
  85         status = acpi_get_table(ACPI_SIG_SPCR, 0,
  86                                 (struct acpi_table_header **)&table);
  87
  88         if (ACPI_FAILURE(status))
  89                 return -ENOENT;
  90
  91         if (table->header.revision < 2) {
  92                 err = -ENOENT;
  93                 pr_err("wrong table version\n");
  94                 goto done;
  95         }
  96
  97         if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
  98                 switch (table->serial_port.access_width) {
  99                 default:
 100                         pr_err("Unexpected SPCR Access Width.  Defaulting to byte size\n");
 101                 case ACPI_ACCESS_SIZE_BYTE:
 102                         iotype = "mmio";
 103                         break;
 104                 case ACPI_ACCESS_SIZE_WORD:
 105                         iotype = "mmio16";
 106                         break;
 107                 case ACPI_ACCESS_SIZE_DWORD:
 108                         iotype = "mmio32";
 109                         break;
 110                 }
 111         } else
 112                 iotype = "io";
 113
 114         switch (table->interface_type) {
 115         case ACPI_DBG2_ARM_SBSA_32BIT:
 116                 iotype = "mmio32";
 117                 /* fall through */
 118         case ACPI_DBG2_ARM_PL011:
 119         case ACPI_DBG2_ARM_SBSA_GENERIC:
 120         case ACPI_DBG2_BCM2835:
 121                 uart = "pl011";
 122                 break;
 123         case ACPI_DBG2_16550_COMPATIBLE:
 124         case ACPI_DBG2_16550_SUBSET:
 125                 uart = "uart";
 126                 break;
 127         default:
 128                 err = -ENOENT;
 129                 goto done;
 130         }
 131
 132         switch (table->baud_rate) {
 133         case 3:
 134                 baud_rate = 9600;
 135                 break;
 136         case 4:
 137                 baud_rate = 19200;
 138                 break;
 139         case 6:
 140                 baud_rate = 57600;
 141                 break;
 142         case 7:
 143                 baud_rate = 115200;
 144                 break;
 145         default:
 146                 err = -ENOENT;
 147                 goto done;
 148         }
 149
 150         if (qdf2400_erratum_44_present(&table->header))
 151                 uart = "qdf2400_e44";
 152         if (xgene_8250_erratum_present(table))
 153                 iotype = "mmio32";
 154
 155         snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
 156                  table->serial_port.address, baud_rate);
 157
 158         pr_info("console: %s\n", opts);
 159
 160         if (earlycon)
 161                 setup_earlycon(opts);
 162
 163         err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
 164
 165 done:
 166         acpi_put_table((struct acpi_table_header *)table);
 167         return err;
 168 }