src/southbridge/intel/lynxpoint/me_9.x.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2011 The Chromium OS Authors. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; version 2 of
 * the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

/*
 * This is a ramstage driver for the Intel Management Engine found in the
 * 6-series chipset.  It handles the required boot-time messages over the
 * MMIO-based Management Engine Interface to tell the ME that the BIOS is
 * finished with POST.  Additional messages are defined for debug but are
 * not used unless the console loglevel is high enough.
 */

#include <arch/acpi.h>
#include <arch/hlt.h>
#include <arch/io.h>
#include <console/console.h>
#include <device/device.h>
#include <device/pci.h>
#include <device/pci_ids.h>
#include <device/pci_def.h>
#include <string.h>
#include <delay.h>
#include <elog.h>

#include "me.h"
#include "pch.h"

#if CONFIG_CHROMEOS
#include <vendorcode/google/chromeos/chromeos.h>
#include <vendorcode/google/chromeos/gnvs.h>
#endif

/* Path that the BIOS should take based on ME state */
static const char *me_bios_path_values[] = {
	[ME_NORMAL_BIOS_PATH]		= "Normal",
	[ME_S3WAKE_BIOS_PATH]		= "S3 Wake",
	[ME_ERROR_BIOS_PATH]		= "Error",
	[ME_RECOVERY_BIOS_PATH]		= "Recovery",
	[ME_DISABLE_BIOS_PATH]		= "Disable",
	[ME_FIRMWARE_UPDATE_BIOS_PATH]	= "Firmware Update",
};
static int intel_me_read_mbp(me_bios_payload *mbp_data, device_t dev);

/* MMIO base address for MEI interface */
static u32 mei_base_address;

#if CONFIG_DEBUG_INTEL_ME
static void mei_dump(void *ptr, int dword, int offset, const char *type)
{
	struct mei_csr *csr;

	printk(BIOS_SPEW, "%-9s[%02x] : ", type, offset);

	switch (offset) {
	case MEI_H_CSR:
	case MEI_ME_CSR_HA:
		csr = ptr;
		if (!csr) {
			printk(BIOS_SPEW, "ERROR: 0x%08x\n", dword);
			break;
		}
		printk(BIOS_SPEW, "cbd=%u cbrp=%02u cbwp=%02u ready=%u "
		       "reset=%u ig=%u is=%u ie=%u\n", csr->buffer_depth,
		       csr->buffer_read_ptr, csr->buffer_write_ptr,
		       csr->ready, csr->reset, csr->interrupt_generate,
		       csr->interrupt_status, csr->interrupt_enable);
		break;
	case MEI_ME_CB_RW:
	case MEI_H_CB_WW:
		printk(BIOS_SPEW, "CB: 0x%08x\n", dword);
		break;
	default:
		printk(BIOS_SPEW, "0x%08x\n", offset);
		break;
	}
}
#else
# define mei_dump(ptr,dword,offset,type) do {} while (0)
#endif

/*
 * ME/MEI access helpers using memcpy to avoid aliasing.
 */

static inline void mei_read_dword_ptr(void *ptr, int offset)
{
	u32 dword = read32(mei_base_address + offset);
	memcpy(ptr, &dword, sizeof(dword));
	mei_dump(ptr, dword, offset, "READ");
}

static inline void mei_write_dword_ptr(void *ptr, int offset)
{
	u32 dword = 0;
	memcpy(&dword, ptr, sizeof(dword));
	write32(mei_base_address + offset, dword);
	mei_dump(ptr, dword, offset, "WRITE");
}

static inline void pci_read_dword_ptr(device_t dev, void *ptr, int offset)
{
	u32 dword = pci_read_config32(dev, offset);
	memcpy(ptr, &dword, sizeof(dword));
	mei_dump(ptr, dword, offset, "PCI READ");
}

static inline void read_host_csr(struct mei_csr *csr)
{
	mei_read_dword_ptr(csr, MEI_H_CSR);
}

static inline void write_host_csr(struct mei_csr *csr)
{
	mei_write_dword_ptr(csr, MEI_H_CSR);
}

static inline void read_me_csr(struct mei_csr *csr)
{
	mei_read_dword_ptr(csr, MEI_ME_CSR_HA);
}

static inline void write_cb(u32 dword)
{
	write32(mei_base_address + MEI_H_CB_WW, dword);
	mei_dump(NULL, dword, MEI_H_CB_WW, "WRITE");
}

static inline u32 read_cb(void)
{
	u32 dword = read32(mei_base_address + MEI_ME_CB_RW);
	mei_dump(NULL, dword, MEI_ME_CB_RW, "READ");
	return dword;
}

/* Wait for ME ready bit to be asserted */
static int mei_wait_for_me_ready(void)
{
	struct mei_csr me;
	unsigned try = ME_RETRY;

	while (try--) {
		read_me_csr(&me);
		if (me.ready)
			return 0;
		udelay(ME_DELAY);
	}

	printk(BIOS_ERR, "ME: failed to become ready\n");
	return -1;
}

static void mei_reset(void)
{
	struct mei_csr host;

	if (mei_wait_for_me_ready() < 0)
		return;

	/* Reset host and ME circular buffers for next message */
	read_host_csr(&host);
	host.reset = 1;
	host.interrupt_generate = 1;
	write_host_csr(&host);

	if (mei_wait_for_me_ready() < 0)
		return;

	/* Re-init and indicate host is ready */
	read_host_csr(&host);
	host.interrupt_generate = 1;
	host.ready = 1;
	host.reset = 0;
	write_host_csr(&host);
}

static int mei_send_msg(struct mei_header *mei, struct mkhi_header *mkhi,
			void *req_data)
{
	struct mei_csr host;
	unsigned ndata, n;
	u32 *data;

	/* Number of dwords to write, ignoring MKHI */
	ndata = mei->length >> 2;

	/* Pad non-dword aligned request message length */
	if (mei->length & 3)
		ndata++;
	if (!ndata) {
		printk(BIOS_DEBUG, "ME: request does not include MKHI\n");
		return -1;
	}
	ndata++; /* Add MEI header */

	/*
	 * Make sure there is still room left in the circular buffer.
	 * Reset the buffer pointers if the requested message will not fit.
	 */
	read_host_csr(&host);
	if ((host.buffer_depth - host.buffer_write_ptr) < ndata) {
		printk(BIOS_ERR, "ME: circular buffer full, resetting...\n");
		mei_reset();
		read_host_csr(&host);
	}

	/*
	 * This implementation does not handle splitting large messages
	 * across multiple transactions.  Ensure the requested length
	 * will fit in the available circular buffer depth.
	 */
	if ((host.buffer_depth - host.buffer_write_ptr) < ndata) {
		printk(BIOS_ERR, "ME: message (%u) too large for buffer (%u)\n",
		       ndata + 2, host.buffer_depth);
		return -1;
	}

	/* Write MEI header */
	mei_write_dword_ptr(mei, MEI_H_CB_WW);
	ndata--;

	/* Write MKHI header */
	mei_write_dword_ptr(mkhi, MEI_H_CB_WW);
	ndata--;

	/* Write message data */
	data = req_data;
	for (n = 0; n < ndata; ++n)
		write_cb(*data++);

	/* Generate interrupt to the ME */
	read_host_csr(&host);
	host.interrupt_generate = 1;
	write_host_csr(&host);

	/* Make sure ME is ready after sending request data */
	return mei_wait_for_me_ready();
}

static int mei_recv_msg(struct mkhi_header *mkhi,
			void *rsp_data, int rsp_bytes)
{
	struct mei_header mei_rsp;
	struct mkhi_header mkhi_rsp;
	struct mei_csr me, host;
	unsigned ndata, n/*, me_data_len*/;
	unsigned expected;
	u32 *data;

	/* Total number of dwords to read from circular buffer */
	expected = (rsp_bytes + sizeof(mei_rsp) + sizeof(mkhi_rsp)) >> 2;
	if (rsp_bytes & 3)
		expected++;

	/*
	 * The interrupt status bit does not appear to indicate that the
	 * message has actually been received.  Instead we wait until the
	 * expected number of dwords are present in the circular buffer.
	 */
	for (n = ME_RETRY; n; --n) {
		read_me_csr(&me);
		if ((me.buffer_write_ptr - me.buffer_read_ptr) >= expected)
			break;
		udelay(ME_DELAY);
	}
	if (!n) {
		printk(BIOS_ERR, "ME: timeout waiting for data: expected "
		       "%u, available %u\n", expected,
		       me.buffer_write_ptr - me.buffer_read_ptr);
		return -1;
	}

	/* Read and verify MEI response header from the ME */
	mei_read_dword_ptr(&mei_rsp, MEI_ME_CB_RW);
	if (!mei_rsp.is_complete) {
		printk(BIOS_ERR, "ME: response is not complete\n");
		return -1;
	}

	/* Handle non-dword responses and expect at least MKHI header */
	ndata = mei_rsp.length >> 2;
	if (mei_rsp.length & 3)
		ndata++;
	if (ndata != (expected - 1)) {
		printk(BIOS_ERR, "ME: response is missing data %d != %d\n",
		       ndata, (expected - 1));
		return -1;
	}

	/* Read and verify MKHI response header from the ME */
	mei_read_dword_ptr(&mkhi_rsp, MEI_ME_CB_RW);
	if (!mkhi_rsp.is_response ||
	    mkhi->group_id != mkhi_rsp.group_id ||
	    mkhi->command != mkhi_rsp.command) {
		printk(BIOS_ERR, "ME: invalid response, group %u ?= %u,"
		       "command %u ?= %u, is_response %u\n", mkhi->group_id,
		       mkhi_rsp.group_id, mkhi->command, mkhi_rsp.command,
		       mkhi_rsp.is_response);
		return -1;
	}
	ndata--; /* MKHI header has been read */

	/* Make sure caller passed a buffer with enough space */
	if (ndata != (rsp_bytes >> 2)) {
		printk(BIOS_ERR, "ME: not enough room in response buffer: "
		       "%u != %u\n", ndata, rsp_bytes >> 2);
		return -1;
	}

	/* Read response data from the circular buffer */
	data = rsp_data;
	for (n = 0; n < ndata; ++n)
		*data++ = read_cb();

	/* Tell the ME that we have consumed the response */
	read_host_csr(&host);
	host.interrupt_status = 1;
	host.interrupt_generate = 1;
	write_host_csr(&host);

	return mei_wait_for_me_ready();
}

static inline int mei_sendrecv(struct mei_header *mei, struct mkhi_header *mkhi,
			       void *req_data, void *rsp_data, int rsp_bytes)
{
	if (mei_send_msg(mei, mkhi, req_data) < 0)
		return -1;
	if (mei_recv_msg(mkhi, rsp_data, rsp_bytes) < 0)
		return -1;
	return 0;
}

#if (CONFIG_DEFAULT_CONSOLE_LOGLEVEL >= BIOS_DEBUG)
static inline void print_cap(const char *name, int state)
{
	printk(BIOS_DEBUG, "ME Capability: %-41s : %sabled\n",
	       name, state ? " en" : "dis");
}

static void me_print_fw_version(mbp_fw_version_name *vers_name)
{
	if (!vers_name) {
		printk(BIOS_ERR, "ME: mbp missing version report\n");
		return;
	}

	printk(BIOS_DEBUG, "ME: found version %d.%d.%d.%d\n",
	       vers_name->major_version, vers_name->minor_version,
	       vers_name->hotfix_version, vers_name->build_version);
}

/* Get ME Firmware Capabilities */
static int mkhi_get_fwcaps(mbp_mefwcaps *cap)
{
	u32 rule_id = 0;
	struct me_fwcaps cap_msg;
	struct mkhi_header mkhi = {
		.group_id       = MKHI_GROUP_ID_FWCAPS,
		.command        = MKHI_FWCAPS_GET_RULE,
	};
	struct mei_header mei = {
		.is_complete    = 1,
		.host_address   = MEI_HOST_ADDRESS,
		.client_address = MEI_ADDRESS_MKHI,
		.length         = sizeof(mkhi) + sizeof(rule_id),
	};

	/* Send request and wait for response */
	if (mei_sendrecv(&mei, &mkhi, &rule_id, &cap_msg, sizeof(cap_msg))
	    < 0) {
		printk(BIOS_ERR, "ME: GET FWCAPS message failed\n");
		return -1;
        }
	*cap = cap_msg.caps_sku;
	return 0;
}

/* Get ME Firmware Capabilities */
static void me_print_fwcaps(mbp_mefwcaps *cap)
{
	mbp_mefwcaps local_caps;
	if (!cap) {
		cap = &local_caps;
		printk(BIOS_ERR, "ME: mbp missing fwcaps report\n");
		if (mkhi_get_fwcaps(cap))
			return;
	}

	print_cap("Full Network manageability", cap->full_net);
	print_cap("Regular Network manageability", cap->std_net);
	print_cap("Manageability", cap->manageability);
	print_cap("IntelR Anti-Theft (AT)", cap->intel_at);
	print_cap("IntelR Capability Licensing Service (CLS)", cap->intel_cls);
	print_cap("IntelR Power Sharing Technology (MPC)", cap->intel_mpc);
	print_cap("ICC Over Clocking", cap->icc_over_clocking);
        print_cap("Protected Audio Video Path (PAVP)", cap->pavp);
	print_cap("IPV6", cap->ipv6);
	print_cap("KVM Remote Control (KVM)", cap->kvm);
	print_cap("Outbreak Containment Heuristic (OCH)", cap->och);
	print_cap("Virtual LAN (VLAN)", cap->vlan);
	print_cap("TLS", cap->tls);
	print_cap("Wireless LAN (WLAN)", cap->wlan);
}
#endif

#if CONFIG_CHROMEOS && 0 /* DISABLED */
/* Tell ME to issue a global reset */
static int mkhi_global_reset(void)
{
	struct me_global_reset reset = {
		.request_origin	= GLOBAL_RESET_BIOS_POST,
		.reset_type	= CBM_RR_GLOBAL_RESET,
	};
	struct mkhi_header mkhi = {
		.group_id	= MKHI_GROUP_ID_CBM,
		.command	= MKHI_GLOBAL_RESET,
	};
	struct mei_header mei = {
		.is_complete	= 1,
		.length		= sizeof(mkhi) + sizeof(reset),
		.host_address	= MEI_HOST_ADDRESS,
		.client_address	= MEI_ADDRESS_MKHI,
	};

	/* Send request and wait for response */
	printk(BIOS_NOTICE, "ME: %s\n", __FUNCTION__);
	if (mei_sendrecv(&mei, &mkhi, &reset, NULL, 0) < 0) {
		/* No response means reset will happen shortly... */
		hlt();
	}

	/* If the ME responded it rejected the reset request */
	printk(BIOS_ERR, "ME: Global Reset failed\n");
	return -1;
}
#endif

/* Send END OF POST message to the ME */
static int mkhi_end_of_post(void)
{
	struct mkhi_header mkhi = {
		.group_id	= MKHI_GROUP_ID_GEN,
		.command	= MKHI_END_OF_POST,
	};
	struct mei_header mei = {
		.is_complete	= 1,
		.host_address	= MEI_HOST_ADDRESS,
		.client_address	= MEI_ADDRESS_MKHI,
		.length		= sizeof(mkhi),
	};

	u32 eop_ack;

	/* Send request and wait for response */
	printk(BIOS_NOTICE, "ME: %s\n", __FUNCTION__);
	if (mei_sendrecv(&mei, &mkhi, NULL, &eop_ack, sizeof(eop_ack)) < 0) {
		printk(BIOS_ERR, "ME: END OF POST message failed\n");
		return -1;
	}

	printk(BIOS_INFO, "ME: END OF POST message successful (%d)\n", eop_ack);
	return 0;
}

/* Determine the path that we should take based on ME status */
static me_bios_path intel_me_path(device_t dev)
{
	me_bios_path path = ME_DISABLE_BIOS_PATH;
	struct me_hfs hfs;
	struct me_hfs2 hfs2;

#if CONFIG_HAVE_ACPI_RESUME
	/* S3 wake skips all MKHI messages */
	if (acpi_slp_type == 3) {
		return ME_S3WAKE_BIOS_PATH;
	}
#endif

	pci_read_dword_ptr(dev, &hfs, PCI_ME_HFS);
	pci_read_dword_ptr(dev, &hfs2, PCI_ME_HFS2);

	/* Check and dump status */
	intel_me_status(&hfs, &hfs2);

	/* Check Current Working State */
	switch (hfs.working_state) {
	case ME_HFS_CWS_NORMAL:
		path = ME_NORMAL_BIOS_PATH;
		break;
	case ME_HFS_CWS_REC:
		path = ME_RECOVERY_BIOS_PATH;
		break;
	default:
		path = ME_DISABLE_BIOS_PATH;
		break;
	}

	/* Check Current Operation Mode */
	switch (hfs.operation_mode) {
	case ME_HFS_MODE_NORMAL:
		break;
	case ME_HFS_MODE_DEBUG:
	case ME_HFS_MODE_DIS:
	case ME_HFS_MODE_OVER_JMPR:
	case ME_HFS_MODE_OVER_MEI:
	default:
		path = ME_DISABLE_BIOS_PATH;
		break;
	}

	/* Check for any error code and valid firmware and MBP */
	if (hfs.error_code || hfs.fpt_bad)
		path = ME_ERROR_BIOS_PATH;

	/* Check if the MBP is ready */
	if (!hfs2.mbp_rdy) {
		printk(BIOS_CRIT, "%s: mbp is not ready!\n",
		       __FUNCTION__);
		path = ME_ERROR_BIOS_PATH;
	}

#if CONFIG_ELOG
	if (path != ME_NORMAL_BIOS_PATH) {
		struct elog_event_data_me_extended data = {
			.current_working_state = hfs.working_state,
			.operation_state       = hfs.operation_state,
			.operation_mode        = hfs.operation_mode,
			.error_code            = hfs.error_code,
			.progress_code         = hfs2.progress_code,
			.current_pmevent       = hfs2.current_pmevent,
			.current_state         = hfs2.current_state,
		};
		elog_add_event_byte(ELOG_TYPE_MANAGEMENT_ENGINE, path);
		elog_add_event_raw(ELOG_TYPE_MANAGEMENT_ENGINE_EXT,
				   &data, sizeof(data));
	}
#endif

	return path;
}

/* Prepare ME for MEI messages */
static int intel_mei_setup(device_t dev)
{
	struct resource *res;
	struct mei_csr host;
	u32 reg32;

	/* Find the MMIO base for the ME interface */
	res = find_resource(dev, PCI_BASE_ADDRESS_0);
	if (!res || res->base == 0 || res->size == 0) {
		printk(BIOS_DEBUG, "ME: MEI resource not present!\n");
		return -1;
	}
	mei_base_address = res->base;

	/* Ensure Memory and Bus Master bits are set */
	reg32 = pci_read_config32(dev, PCI_COMMAND);
	reg32 |= PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY;
	pci_write_config32(dev, PCI_COMMAND, reg32);

	/* Clean up status for next message */
	read_host_csr(&host);
	host.interrupt_generate = 1;
	host.ready = 1;
	host.reset = 0;
	write_host_csr(&host);

	return 0;
}

/* Read the Extend register hash of ME firmware */
static int intel_me_extend_valid(device_t dev)
{
	struct me_heres status;
	u32 extend[8] = {0};
	int i, count = 0;

	pci_read_dword_ptr(dev, &status, PCI_ME_HERES);
	if (!status.extend_feature_present) {
		printk(BIOS_ERR, "ME: Extend Feature not present\n");
		return -1;
	}

	if (!status.extend_reg_valid) {
		printk(BIOS_ERR, "ME: Extend Register not valid\n");
		return -1;
	}

	switch (status.extend_reg_algorithm) {
	case PCI_ME_EXT_SHA1:
		count = 5;
		printk(BIOS_DEBUG, "ME: Extend SHA-1: ");
		break;
	case PCI_ME_EXT_SHA256:
		count = 8;
		printk(BIOS_DEBUG, "ME: Extend SHA-256: ");
		break;
	default:
		printk(BIOS_ERR, "ME: Extend Algorithm %d unknown\n",
		       status.extend_reg_algorithm);
		return -1;
	}

	for (i = 0; i < count; ++i) {
		extend[i] = pci_read_config32(dev, PCI_ME_HER(i));
		printk(BIOS_DEBUG, "%08x", extend[i]);
	}
	printk(BIOS_DEBUG, "\n");

#if CONFIG_CHROMEOS
	/* Save hash in NVS for the OS to verify */
	chromeos_set_me_hash(extend, count);
#endif

	return 0;
}

/* Hide the ME virtual PCI devices */
static void intel_me_hide(device_t dev)
{
	/* Make sure IO is disabled */
	u32 reg32 = pci_read_config32(dev, PCI_COMMAND);
	reg32 &= ~(PCI_COMMAND_MASTER |
		   PCI_COMMAND_MEMORY | PCI_COMMAND_IO);
	pci_write_config32(dev, PCI_COMMAND, reg32);

	dev->enabled = 0;
	pch_enable(dev);
}

/* Check whether ME is present and do basic init */
static void intel_me_init(device_t dev)
{
	me_bios_path path = intel_me_path(dev);
	me_bios_payload mbp_data;

	/* Do initial setup and determine the BIOS path */
	printk(BIOS_NOTICE, "ME: BIOS path: %s\n", me_bios_path_values[path]);

	if (path == ME_S3WAKE_BIOS_PATH) {
		intel_me_hide(dev);
		return;
	} else if (path == ME_NORMAL_BIOS_PATH) {
		/* Validate the extend register */
		/* FIXME: force recovery mode on failure. */
		intel_me_extend_valid(dev);
	}

	memset(&mbp_data, 0, sizeof(mbp_data));

	/*
	 * According to the ME9 BWG, BIOS is required to fetch MBP data in
	 * all boot flows except S3 Resume.
	 */

	/* Prepare MEI MMIO interface */
	if (intel_mei_setup(dev) < 0)
		return;

	if (intel_me_read_mbp(&mbp_data, dev))
		return;

#if (CONFIG_DEFAULT_CONSOLE_LOGLEVEL >= BIOS_DEBUG)
	me_print_fw_version(mbp_data.fw_version_name);
	me_print_fwcaps(mbp_data.fw_capabilities);

	if (mbp_data.plat_time) {
		printk(BIOS_DEBUG, "ME: Wake Event to ME Reset:      %u ms\n",
		       mbp_data.plat_time->wake_event_mrst_time_ms);
		printk(BIOS_DEBUG, "ME: ME Reset to Platform Reset:  %u ms\n",
		       mbp_data.plat_time->mrst_pltrst_time_ms);
		printk(BIOS_DEBUG, "ME: Platform Reset to CPU Reset: %u ms\n",
		       mbp_data.plat_time->pltrst_cpurst_time_ms);
	}
#endif

	/* Lock down and hide Management Engine */
	mkhi_end_of_post();
	intel_me_hide(dev);
}

static void set_subsystem(device_t dev, unsigned vendor, unsigned device)
{
	if (!vendor || !device) {
		pci_write_config32(dev, PCI_SUBSYSTEM_VENDOR_ID,
			   pci_read_config32(dev, PCI_VENDOR_ID));
	} else {
		pci_write_config32(dev, PCI_SUBSYSTEM_VENDOR_ID,
			   ((device & 0xffff) << 16) | (vendor & 0xffff));
	}
}

static struct pci_operations pci_ops = {
	.set_subsystem = set_subsystem,
};

static struct device_operations device_ops = {
	.read_resources		= pci_dev_read_resources,
	.set_resources		= pci_dev_set_resources,
	.enable_resources	= pci_dev_enable_resources,
	.init			= intel_me_init,
	.scan_bus		= scan_static_bus,
	.ops_pci		= &pci_ops,
};

static const unsigned short pci_device_ids[] = {
	0x8c3a, /* Mobile */
	0x9c3a, /* Low Power */
	0
};

static const struct pci_driver intel_me __pci_driver = {
	.ops	= &device_ops,
	.vendor	= PCI_VENDOR_ID_INTEL,
	.devices= pci_device_ids,
};

/******************************************************************************
 *									     */
static u32 me_to_host_words_pending(void)
{
	struct mei_csr me;
	read_me_csr(&me);
	if (!me.ready)
		return 0;
	return (me.buffer_write_ptr - me.buffer_read_ptr) &
		(me.buffer_depth - 1);
}

#if 0
/* This function is not yet being used, keep it in for the future. */
static u32 host_to_me_words_room(void)
{
	struct mei_csr csr;

	read_me_csr(&csr);
	if (!csr.ready)
		return 0;

	read_host_csr(&csr);
	return (csr.buffer_read_ptr - csr.buffer_write_ptr - 1) &
		(csr.buffer_depth - 1);
}
#endif

/*
 * mbp give up routine. This path is taken if hfs.mpb_rdy is 0 or the read
 * state machine on the BIOS end doesn't match the ME's state machine.
 */
static void intel_me_mbp_give_up(device_t dev)
{
	u32 reg32;
	struct mei_csr csr;

	reg32 = PCI_ME_MBP_GIVE_UP;
	pci_write_config32(dev, PCI_ME_H_GS2, reg32);
	read_host_csr(&csr);
	csr.reset = 1;
	csr.interrupt_generate = 1;
	write_host_csr(&csr);
}

struct mbp_payload {
	mbp_header header;
	u32 data[0];
};

/*
 * mbp seems to be following its own flow, let's retrieve it in a dedicated
 * function.
 */
static int intel_me_read_mbp(me_bios_payload *mbp_data, device_t dev)
{
	mbp_header mbp_hdr;
	u32 me2host_pending;
	struct mei_csr host;
	struct me_hfs2 hfs2;
	int count;
	struct mbp_payload *mbp;
	int i;

	pci_read_dword_ptr(dev, &hfs2, PCI_ME_HFS2);

	if (!hfs2.mbp_rdy) {
		printk(BIOS_ERR, "ME: MBP not ready\n");
		goto mbp_failure;
	}

	me2host_pending = me_to_host_words_pending();
	if (!me2host_pending) {
		printk(BIOS_ERR, "ME: no mbp data!\n");
		goto mbp_failure;
	}

	/* we know for sure that at least the header is there */
	mei_read_dword_ptr(&mbp_hdr, MEI_ME_CB_RW);

	if ((mbp_hdr.num_entries > (mbp_hdr.mbp_size / 2)) ||
	    (me2host_pending < mbp_hdr.mbp_size)) {
		printk(BIOS_ERR, "ME: mbp of %d entries, total size %d words"
		       " buffer contains %d words\n",
		       mbp_hdr.num_entries, mbp_hdr.mbp_size,
		       me2host_pending);
		goto mbp_failure;
	}
	mbp = malloc(mbp_hdr.mbp_size * sizeof(u32));
	if (!mbp)
		goto mbp_failure;

	mbp->header = mbp_hdr;
	me2host_pending--;

	i = 0;
	while (i != me2host_pending) {
		mei_read_dword_ptr(&mbp->data[i], MEI_ME_CB_RW);
		i++;
	}

	/* Signal to the ME that the host has finished reading the MBP. */
	read_host_csr(&host);
	host.interrupt_generate = 1;
	write_host_csr(&host);

	/* Wait for the mbp_cleared indicator. */
	for (count = ME_RETRY; count > 0; --count) {
		pci_read_dword_ptr(dev, &hfs2, PCI_ME_HFS2);
		if (hfs2.mbp_cleared)
			break;
		udelay(ME_DELAY);
	}

	if (count == 0) {
		printk(BIOS_WARNING, "ME: Timeout waiting for mbp_cleared\n");
		intel_me_mbp_give_up(dev);
	}

	/* Dump out the MBP contents. */
#if (CONFIG_DEFAULT_CONSOLE_LOGLEVEL >= BIOS_DEBUG)
	printk(BIOS_INFO, "ME MBP: Header: items: %d, size dw: %d\n",
	       mbp->header.num_entries, mbp->header.mbp_size);
	for (i = 0; i < mbp->header.mbp_size - 1; i++) {
		printk(BIOS_INFO, "ME MBP: %04x: 0x%08x\n", i, mbp->data[i]);
	}
#endif

	#define ASSIGN_FIELD_PTR(field_,val_) \
		{ \
		mbp_data->field_ = (typeof(mbp_data->field_))(void *)val_; \
		break; \
		}
	/* Setup the pointers in the me_bios_payload structure. */
	for (i = 0; i < mbp->header.mbp_size - 1;) {
		mbp_item_header *item = (void *)&mbp->data[i];

		switch(MBP_MAKE_IDENT(item->app_id, item->item_id)) {
		case MBP_IDENT(KERNEL, FW_VER):
			ASSIGN_FIELD_PTR(fw_version_name, &mbp->data[i+1]);

		case MBP_IDENT(ICC, PROFILE):
			ASSIGN_FIELD_PTR(icc_profile, &mbp->data[i+1]);

		case MBP_IDENT(INTEL_AT, STATE):
			ASSIGN_FIELD_PTR(at_state, &mbp->data[i+1]);

		case MBP_IDENT(KERNEL, FW_CAP):
			ASSIGN_FIELD_PTR(fw_capabilities, &mbp->data[i+1]);

		case MBP_IDENT(KERNEL, ROM_BIST):
			ASSIGN_FIELD_PTR(rom_bist_data, &mbp->data[i+1]);

		case MBP_IDENT(KERNEL, PLAT_KEY):
			ASSIGN_FIELD_PTR(platform_key, &mbp->data[i+1]);

		case MBP_IDENT(KERNEL, FW_TYPE):
			ASSIGN_FIELD_PTR(fw_plat_type, &mbp->data[i+1]);

		case MBP_IDENT(KERNEL, MFS_FAILURE):
			ASSIGN_FIELD_PTR(mfsintegrity, &mbp->data[i+1]);

		case MBP_IDENT(KERNEL, PLAT_TIME):
			ASSIGN_FIELD_PTR(plat_time, &mbp->data[i+1]);

		case MBP_IDENT(NFC, SUPPORT_DATA):
			ASSIGN_FIELD_PTR(nfc_data, &mbp->data[i+1]);

		default:
			printk(BIOS_ERR, "ME MBP: unknown item 0x%x @ dw offset 0x%x\n",
			       mbp->data[i], i);
			break;
		}
		i += item->length;
	}
	#undef ASSIGN_FIELD_PTR

	return 0;

mbp_failure:
	intel_me_mbp_give_up(dev);
	return -1;
}