#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/dmi.h>
+#include <linux/mm.h>
#include <asm/bios_ebda.h>
+#include <asm/e820.h>
+#include <acpi/acpi_bus.h>
#define BIOS_MEMCONSOLE_V1_MAGIC 0xDEADBABE
#define BIOS_MEMCONSOLE_V2_MAGIC (('M')|('C'<<8)|('O'<<16)|('N'<<24))
static char *memconsole_baseaddr;
static size_t memconsole_length;
+static bool coreboot_system;
+
+static int set_coreboot_system_flag(const struct dmi_system_id *unused)
+{
+ coreboot_system = true;
+ return true;
+}
static ssize_t memconsole_read(struct file *filp, struct kobject *kobp,
struct bin_attribute *bin_attr, char *buf,
+ hdr->v2.start);
}
+/*
+ * The function below tries to find the firmware console log saved in the
+ * appropriate coreboot CBMEM section, using the structures and constants from
+ * coreboot code.
+ *
+ * Coreboot's CBMEM is a structure allocated by coreboot above usable memory
+ * at a 128K aligned address. One of the CBMEM sections could contain the
+ * firmare console log.
+ */
+
+/* Coreboot CBMEM section descriptor. */
+struct cbmem_entry {
+ u32 magic;
+ u32 id;
+ u64 base;
+ u64 size;
+} __packed;
+
+/* CBMEM firmware console log descriptor. */
+struct cbmem_cons {
+ u32 buffer_size;
+ u32 buffer_cursor;
+ u8 buffer_body[0];
+} __packed;
+
+struct cbmem_cons __iomem *cbmem_console;
+
+/* coreboot CBMEM constants */
+#define CBMEM_ALIGNMENT (128 * 1024)
+#define MEMORY_BOUNDARY (1024 * 1024 * 1024)
+#define MAX_CBMEM_ENTRIES 16
+#define CBMEM_ENTRY_MAGIC 0x434f5245
+#define CBMEM_CONSOLE_ID 0x434f4e53
+#define CBMEM_ACPI_NAME "\\CMEM"
+
+static bool check_cbmem(void)
+{
+ struct sysinfo sysi;
+ phys_addr_t top_of_ram, scan_addr = 0;
+ acpi_handle handle;
+ acpi_status status;
+ unsigned long long value;
+
+ /*
+ * Attempt to use defined ACPI name to locate CBMEM TOC.
+ */
+ status = acpi_get_handle(NULL, CBMEM_ACPI_NAME, &handle);
+ if (ACPI_SUCCESS(status)) {
+ status = acpi_evaluate_integer(handle, CBMEM_ACPI_NAME,
+ NULL, &value);
+ /* Start scan at this address */
+ if (ACPI_SUCCESS(status) && value > 0)
+ scan_addr = (phys_addr_t) value;
+ }
+
+ /*
+ * Otherwise determine where to start looking for CBMEM signature:
+ * take the top of usable memory and align it up to 128K boundary.
+ */
+ if (!scan_addr) {
+ si_meminfo(&sysi);
+ top_of_ram = (phys_addr_t) sysi.totalram << PAGE_SHIFT;
+ scan_addr = ALIGN(top_of_ram, CBMEM_ALIGNMENT) +
+ CBMEM_ALIGNMENT;
+ }
+
+ while (scan_addr % MEMORY_BOUNDARY) {
+ struct cbmem_entry __iomem *pcbm;
+ int i, remap_size = sizeof(struct cbmem_entry) * 16;
+
+ /*
+ * See if we reached reserved memory. Bail out if so, as it is
+ * not mappable and is above the region where the CBMEM could
+ * be.
+ */
+ if (e820_any_mapped(scan_addr,
+ scan_addr + remap_size,
+ E820_RESERVED))
+ break;
+
+ pcbm = ioremap_cache(scan_addr, remap_size);
+ if (!pcbm) {
+ scan_addr += CBMEM_ALIGNMENT;
+ continue;
+ }
+
+ if (pcbm->magic != CBMEM_ENTRY_MAGIC) {
+ iounmap(pcbm);
+ scan_addr += CBMEM_ALIGNMENT;
+ continue;
+ }
+
+ /* CBMEM found. Is the console log there? */
+ for (i = 1; i < MAX_CBMEM_ENTRIES; i++) {
+ if ((pcbm[i].magic == CBMEM_ENTRY_MAGIC) &&
+ (pcbm[i].id == CBMEM_CONSOLE_ID)) {
+ /* Yes, map the log. */
+ cbmem_console = ioremap_cache(pcbm[i].base,
+ pcbm[i].size);
+ break;
+ }
+ }
+ iounmap(pcbm);
+ break;
+ }
+
+ if (cbmem_console) {
+ memconsole_baseaddr = cbmem_console->buffer_body;
+ memconsole_length = min(cbmem_console->buffer_cursor,
+ cbmem_console->buffer_size);
+ return true;
+ }
+
+ printk(KERN_INFO "CBMEM console structure not found!\n");
+ return false;
+}
+
/*
* Search through the EBDA for the BIOS Memory Console, and
* set the global variables to point to it. Return true if found.
unsigned int address;
size_t length, cur;
+ /* Is it communicated through CBMEM? */
+ if (coreboot_system && check_cbmem())
+ return true;
+
address = get_bios_ebda();
if (!address) {
printk(KERN_INFO "BIOS EBDA non-existent.\n");
DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
},
},
+ {
+ .ident = "Google Board",
+ .callback = set_coreboot_system_flag,
+ .matches = {
+ DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
+ },
+ },
{}
};
MODULE_DEVICE_TABLE(dmi, memconsole_dmi_table);
static void __exit memconsole_exit(void)
{
+ if (cbmem_console)
+ iounmap(cbmem_console);
+
sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr);
}