350 lines
8.1 KiB
C
350 lines
8.1 KiB
C
/*
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* memconsole.c
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*
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* Infrastructure for importing the BIOS memory based console
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* into the kernel log ringbuffer.
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*
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* Copyright 2010 Google Inc. All rights reserved.
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*/
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#include <linux/ctype.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/dmi.h>
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#include <linux/mm.h>
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#include <asm/bios_ebda.h>
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#include <asm/e820.h>
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#include <acpi/acpi_bus.h>
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#define BIOS_MEMCONSOLE_V1_MAGIC 0xDEADBABE
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#define BIOS_MEMCONSOLE_V2_MAGIC (('M')|('C'<<8)|('O'<<16)|('N'<<24))
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struct biosmemcon_ebda {
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u32 signature;
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union {
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struct {
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u8 enabled;
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u32 buffer_addr;
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u16 start;
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u16 end;
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u16 num_chars;
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u8 wrapped;
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} __packed v1;
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struct {
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u32 buffer_addr;
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/* Misdocumented as number of pages! */
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u16 num_bytes;
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u16 start;
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u16 end;
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} __packed v2;
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};
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} __packed;
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static char *memconsole_baseaddr;
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static size_t memconsole_length;
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static bool coreboot_system;
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static int set_coreboot_system_flag(const struct dmi_system_id *unused)
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{
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coreboot_system = true;
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return true;
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}
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static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
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struct bin_attribute *bin_attr, char *buf,
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loff_t pos, size_t count)
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{
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return memory_read_from_buffer(buf, count, &pos, memconsole_baseaddr,
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memconsole_length);
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}
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static struct bin_attribute memconsole_bin_attr = {
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.attr = {.name = "log", .mode = 0444},
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.read = memconsole_read,
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};
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static void found_v1_header(struct biosmemcon_ebda *hdr)
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{
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printk(KERN_INFO "BIOS console v1 EBDA structure found at %p\n", hdr);
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printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
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"start = %d, end = %d, num = %d\n",
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hdr->v1.buffer_addr, hdr->v1.start,
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hdr->v1.end, hdr->v1.num_chars);
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memconsole_length = hdr->v1.num_chars;
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memconsole_baseaddr = phys_to_virt(hdr->v1.buffer_addr);
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}
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static void found_v2_header(struct biosmemcon_ebda *hdr)
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{
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printk(KERN_INFO "BIOS console v2 EBDA structure found at %p\n", hdr);
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printk(KERN_INFO "BIOS console buffer at 0x%.8x, "
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"start = %d, end = %d, num_bytes = %d\n",
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hdr->v2.buffer_addr, hdr->v2.start,
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hdr->v2.end, hdr->v2.num_bytes);
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memconsole_length = hdr->v2.end - hdr->v2.start;
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memconsole_baseaddr = phys_to_virt(hdr->v2.buffer_addr
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+ hdr->v2.start);
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}
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/*
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* The function below tries to find the firmware console log saved in the
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* appropriate coreboot CBMEM section, using the structures and constants from
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* coreboot code.
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*
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* Coreboot's CBMEM is a structure allocated by coreboot above usable memory
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* at a 128K aligned address. One of the CBMEM sections could contain the
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* firmare console log.
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*/
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/* Coreboot CBMEM section descriptor. */
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struct cbmem_entry {
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u32 magic;
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u32 id;
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u64 base;
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u64 size;
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} __packed;
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/* CBMEM firmware console log descriptor. */
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struct cbmem_cons {
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u32 buffer_size;
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u32 buffer_cursor;
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u8 buffer_body[0];
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} __packed;
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struct cbmem_cons __iomem *cbmem_console;
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/* coreboot CBMEM constants */
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#define CBMEM_ALIGNMENT (128 * 1024)
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#define MEMORY_BOUNDARY (1024 * 1024 * 1024)
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#define MAX_CBMEM_ENTRIES 16
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#define CBMEM_ENTRY_MAGIC 0x434f5245
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#define CBMEM_CONSOLE_ID 0x434f4e53
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#define CBMEM_ACPI_NAME "\\CMEM"
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#define CBMEMC_ACPI_NAME "\\CBMC"
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static bool check_acpi_coreboot_memconsole(void)
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{
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acpi_handle handle;
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acpi_status status;
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unsigned long long value;
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struct cbmem_cons __iomem *tmp_cbmc;
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/*
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* Attempt to use defined ACPI name to locate coreboot mem console.
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*/
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status = acpi_get_handle(NULL, CBMEMC_ACPI_NAME, &handle);
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if (!ACPI_SUCCESS(status))
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return false;
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status = acpi_evaluate_integer(handle, CBMEMC_ACPI_NAME,
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NULL, &value);
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/* Start scan at this address */
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if (!ACPI_SUCCESS(status) || value == 0)
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return false;
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tmp_cbmc = ioremap_cache(value, sizeof(*tmp_cbmc));
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if (tmp_cbmc == NULL)
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return false;
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cbmem_console = ioremap_cache(value, tmp_cbmc->buffer_size);
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iounmap(tmp_cbmc);
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if (cbmem_console == NULL)
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return false;
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memconsole_baseaddr = cbmem_console->buffer_body;
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memconsole_length = min(cbmem_console->buffer_cursor,
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cbmem_console->buffer_size);
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return true;
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}
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static bool check_cbmem(void)
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{
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struct sysinfo sysi;
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phys_addr_t top_of_ram, scan_addr = 0;
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acpi_handle handle;
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acpi_status status;
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unsigned long long value;
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if (check_acpi_coreboot_memconsole())
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return true;
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/*
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* Attempt to use defined ACPI name to locate CBMEM TOC.
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*/
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status = acpi_get_handle(NULL, CBMEM_ACPI_NAME, &handle);
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if (ACPI_SUCCESS(status)) {
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status = acpi_evaluate_integer(handle, CBMEM_ACPI_NAME,
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NULL, &value);
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/* Start scan at this address */
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if (ACPI_SUCCESS(status) && value > 0)
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scan_addr = (phys_addr_t) value;
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}
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/*
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* Otherwise determine where to start looking for CBMEM signature:
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* take the top of usable memory and align it up to 128K boundary.
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*/
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if (!scan_addr) {
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si_meminfo(&sysi);
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top_of_ram = (phys_addr_t) sysi.totalram << PAGE_SHIFT;
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scan_addr = ALIGN(top_of_ram, CBMEM_ALIGNMENT) +
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CBMEM_ALIGNMENT;
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}
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while (scan_addr % MEMORY_BOUNDARY) {
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struct cbmem_entry __iomem *pcbm;
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int i, remap_size = sizeof(struct cbmem_entry) * 16;
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/*
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* See if we reached reserved memory. Bail out if so, as it is
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* not mappable and is above the region where the CBMEM could
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* be.
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*/
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if (e820_any_mapped(scan_addr,
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scan_addr + remap_size,
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E820_RESERVED))
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break;
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pcbm = ioremap_cache(scan_addr, remap_size);
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if (!pcbm) {
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scan_addr += CBMEM_ALIGNMENT;
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continue;
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}
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if (pcbm->magic != CBMEM_ENTRY_MAGIC) {
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iounmap(pcbm);
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scan_addr += CBMEM_ALIGNMENT;
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continue;
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}
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/* CBMEM found. Is the console log there? */
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for (i = 1; i < MAX_CBMEM_ENTRIES; i++) {
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if ((pcbm[i].magic == CBMEM_ENTRY_MAGIC) &&
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(pcbm[i].id == CBMEM_CONSOLE_ID)) {
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/* Yes, map the log. */
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cbmem_console = ioremap_cache(pcbm[i].base,
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pcbm[i].size);
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break;
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}
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}
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iounmap(pcbm);
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break;
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}
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if (cbmem_console) {
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memconsole_baseaddr = cbmem_console->buffer_body;
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memconsole_length = min(cbmem_console->buffer_cursor,
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cbmem_console->buffer_size);
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return true;
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}
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printk(KERN_INFO "CBMEM console structure not found!\n");
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return false;
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}
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/*
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* Search through the EBDA for the BIOS Memory Console, and
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* set the global variables to point to it. Return true if found.
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*/
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static bool found_memconsole(void)
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{
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unsigned int address;
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size_t length, cur;
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/* Is it communicated through CBMEM? */
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if (coreboot_system && check_cbmem())
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return true;
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address = get_bios_ebda();
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if (!address) {
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printk(KERN_INFO "BIOS EBDA non-existent.\n");
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return false;
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}
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/* EBDA length is byte 0 of EBDA (in KB) */
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length = *(u8 *)phys_to_virt(address);
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length <<= 10; /* convert to bytes */
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/*
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* Search through EBDA for BIOS memory console structure
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* note: signature is not necessarily dword-aligned
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*/
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for (cur = 0; cur < length; cur++) {
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struct biosmemcon_ebda *hdr = phys_to_virt(address + cur);
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/* memconsole v1 */
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if (hdr->signature == BIOS_MEMCONSOLE_V1_MAGIC) {
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found_v1_header(hdr);
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return true;
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}
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/* memconsole v2 */
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if (hdr->signature == BIOS_MEMCONSOLE_V2_MAGIC) {
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found_v2_header(hdr);
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return true;
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}
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}
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printk(KERN_INFO "BIOS console EBDA structure not found!\n");
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return false;
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}
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static struct dmi_system_id memconsole_dmi_table[] __initdata = {
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{
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.ident = "Google Board",
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.matches = {
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DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
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},
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},
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{
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.ident = "Google Board",
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.callback = set_coreboot_system_flag,
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.matches = {
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DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
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},
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},
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{}
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};
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MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table);
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static int __init memconsole_init(void)
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{
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int ret;
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if (!dmi_check_system(memconsole_dmi_table))
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return -ENODEV;
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if (!found_memconsole())
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return -ENODEV;
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memconsole_bin_attr.size = memconsole_length;
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ret = sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr);
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return ret;
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}
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static void __exit memconsole_exit(void)
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{
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if (cbmem_console)
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iounmap(cbmem_console);
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sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
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}
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module_init(memconsole_init);
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module_exit(memconsole_exit);
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MODULE_AUTHOR("Google, Inc.");
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MODULE_LICENSE("GPL");
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