drivers/net/wireless/intel/iwlwifi/iwl-eeprom-read.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
 /*
  * Copyright (C) 2005-2014, 2018-2019 Intel Corporation
  */
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/export.h>

 #include "iwl-drv.h"
 #include "iwl-debug.h"
 #include "iwl-eeprom-read.h"
 #include "iwl-io.h"
 #include "iwl-prph.h"
 #include "iwl-csr.h"

 /*
  * EEPROM access time values:
  *
  * Driver initiates EEPROM read by writing byte address << 1 to CSR_EEPROM_REG.
  * Driver then polls CSR_EEPROM_REG for CSR_EEPROM_REG_READ_VALID_MSK (0x1).
  * When polling, wait 10 uSec between polling loops, up to a maximum 5000 uSec.
  * Driver reads 16-bit value from bits 31-16 of CSR_EEPROM_REG.
  */
 #define IWL_EEPROM_ACCESS_TIMEOUT	5000 /* uSec */

 #define IWL_EEPROM_SEM_TIMEOUT		10   /* microseconds */
 #define IWL_EEPROM_SEM_RETRY_LIMIT	1000 /* number of attempts (not time) */


 /*
  * The device's EEPROM semaphore prevents conflicts between driver and uCode
  * when accessing the EEPROM; each access is a series of pulses to/from the
  * EEPROM chip, not a single event, so even reads could conflict if they
  * weren't arbitrated by the semaphore.
  */

 #define	EEPROM_SEM_TIMEOUT 10		/* milliseconds */
 #define EEPROM_SEM_RETRY_LIMIT 1000	/* number of attempts (not time) */

 static int iwl_eeprom_acquire_semaphore(struct iwl_trans *trans)
 {
 	u16 count;
 	int ret;

 	for (count = 0; count < EEPROM_SEM_RETRY_LIMIT; count++) {
 		/* Request semaphore */
 		iwl_set_bit(trans, CSR_HW_IF_CONFIG_REG,
 			    CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM);

 		/* See if we got it */
 		ret = iwl_poll_bit(trans, CSR_HW_IF_CONFIG_REG,
 				CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM,
 				CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM,
 				EEPROM_SEM_TIMEOUT);
 		if (ret >= 0) {
 			IWL_DEBUG_EEPROM(trans->dev,
 					 "Acquired semaphore after %d tries.\n",
 					 count+1);
 			return ret;
 		}
 	}

 	return ret;
 }

 static void iwl_eeprom_release_semaphore(struct iwl_trans *trans)
 {
 	iwl_clear_bit(trans, CSR_HW_IF_CONFIG_REG,
 		      CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM);
 }

 static int iwl_eeprom_verify_signature(struct iwl_trans *trans, bool nvm_is_otp)
 {
 	u32 gp = iwl_read32(trans, CSR_EEPROM_GP) & CSR_EEPROM_GP_VALID_MSK;

 	IWL_DEBUG_EEPROM(trans->dev, "EEPROM signature=0x%08x\n", gp);

 	switch (gp) {
 	case CSR_EEPROM_GP_BAD_SIG_EEP_GOOD_SIG_OTP:
 		if (!nvm_is_otp) {
 			IWL_ERR(trans, "EEPROM with bad signature: 0x%08x\n",
 				gp);
 			return -ENOENT;
 		}
 		return 0;
 	case CSR_EEPROM_GP_GOOD_SIG_EEP_LESS_THAN_4K:
 	case CSR_EEPROM_GP_GOOD_SIG_EEP_MORE_THAN_4K:
 		if (nvm_is_otp) {
 			IWL_ERR(trans, "OTP with bad signature: 0x%08x\n", gp);
 			return -ENOENT;
 		}
 		return 0;
 	case CSR_EEPROM_GP_BAD_SIGNATURE_BOTH_EEP_AND_OTP:
 	default:
 		IWL_ERR(trans,
 			"bad EEPROM/OTP signature, type=%s, EEPROM_GP=0x%08x\n",
 			nvm_is_otp ? "OTP" : "EEPROM", gp);
 		return -ENOENT;
 	}
 }

 /******************************************************************************
  *
  * OTP related functions
  *
 ******************************************************************************/

 static void iwl_set_otp_access_absolute(struct iwl_trans *trans)
 {
 	iwl_read32(trans, CSR_OTP_GP_REG);

 	iwl_clear_bit(trans, CSR_OTP_GP_REG,
 		      CSR_OTP_GP_REG_OTP_ACCESS_MODE);
 }

 static int iwl_nvm_is_otp(struct iwl_trans *trans)
 {
 	u32 otpgp;

 	/* OTP only valid for CP/PP and after */
 	switch (trans->hw_rev & CSR_HW_REV_TYPE_MSK) {
 	case CSR_HW_REV_TYPE_NONE:
 		IWL_ERR(trans, "Unknown hardware type\n");
 		return -EIO;
 	case CSR_HW_REV_TYPE_5300:
 	case CSR_HW_REV_TYPE_5350:
 	case CSR_HW_REV_TYPE_5100:
 	case CSR_HW_REV_TYPE_5150:
 		return 0;
 	default:
 		otpgp = iwl_read32(trans, CSR_OTP_GP_REG);
 		if (otpgp & CSR_OTP_GP_REG_DEVICE_SELECT)
 			return 1;
 		return 0;
 	}
 }

 static int iwl_init_otp_access(struct iwl_trans *trans)
 {
 	int ret;

 	ret = iwl_finish_nic_init(trans, trans->trans_cfg);
 	if (ret)
 		return ret;

 	iwl_set_bits_prph(trans, APMG_PS_CTRL_REG,
 			  APMG_PS_CTRL_VAL_RESET_REQ);
 	udelay(5);
 	iwl_clear_bits_prph(trans, APMG_PS_CTRL_REG,
 			    APMG_PS_CTRL_VAL_RESET_REQ);

 	/*
 	 * CSR auto clock gate disable bit -
 	 * this is only applicable for HW with OTP shadow RAM
 	 */
 	if (trans->trans_cfg->base_params->shadow_ram_support)
 		iwl_set_bit(trans, CSR_DBG_LINK_PWR_MGMT_REG,
 			    CSR_RESET_LINK_PWR_MGMT_DISABLED);

 	return 0;
 }

 static int iwl_read_otp_word(struct iwl_trans *trans, u16 addr,
 			     __le16 *eeprom_data)
 {
 	int ret = 0;
 	u32 r;
 	u32 otpgp;

 	iwl_write32(trans, CSR_EEPROM_REG,
 		    CSR_EEPROM_REG_MSK_ADDR & (addr << 1));
 	ret = iwl_poll_bit(trans, CSR_EEPROM_REG,
 				 CSR_EEPROM_REG_READ_VALID_MSK,
 				 CSR_EEPROM_REG_READ_VALID_MSK,
 				 IWL_EEPROM_ACCESS_TIMEOUT);
 	if (ret < 0) {
 		IWL_ERR(trans, "Time out reading OTP[%d]\n", addr);
 		return ret;
 	}
 	r = iwl_read32(trans, CSR_EEPROM_REG);
 	/* check for ECC errors: */
 	otpgp = iwl_read32(trans, CSR_OTP_GP_REG);
 	if (otpgp & CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK) {
 		/* stop in this case */
 		/* set the uncorrectable OTP ECC bit for acknowledgment */
 		iwl_set_bit(trans, CSR_OTP_GP_REG,
 			    CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK);
 		IWL_ERR(trans, "Uncorrectable OTP ECC error, abort OTP read\n");
 		return -EINVAL;
 	}
 	if (otpgp & CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK) {
 		/* continue in this case */
 		/* set the correctable OTP ECC bit for acknowledgment */
 		iwl_set_bit(trans, CSR_OTP_GP_REG,
 			    CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK);
 		IWL_ERR(trans, "Correctable OTP ECC error, continue read\n");
 	}
 	*eeprom_data = cpu_to_le16(r >> 16);
 	return 0;
 }

 /*
  * iwl_is_otp_empty: check for empty OTP
  */
 static bool iwl_is_otp_empty(struct iwl_trans *trans)
 {
 	u16 next_link_addr = 0;
 	__le16 link_value;
 	bool is_empty = false;

 	/* locate the beginning of OTP link list */
 	if (!iwl_read_otp_word(trans, next_link_addr, &link_value)) {
 		if (!link_value) {
 			IWL_ERR(trans, "OTP is empty\n");
 			is_empty = true;
 		}
 	} else {
 		IWL_ERR(trans, "Unable to read first block of OTP list.\n");
 		is_empty = true;
 	}

 	return is_empty;
 }


 /*
  * iwl_find_otp_image: find EEPROM image in OTP
  *   finding the OTP block that contains the EEPROM image.
  *   the last valid block on the link list (the block _before_ the last block)
  *   is the block we should read and used to configure the device.
  *   If all the available OTP blocks are full, the last block will be the block
  *   we should read and used to configure the device.
  *   only perform this operation if shadow RAM is disabled
  */
 static int iwl_find_otp_image(struct iwl_trans *trans,
 					u16 *validblockaddr)
 {
 	u16 next_link_addr = 0, valid_addr;
 	__le16 link_value = 0;
 	int usedblocks = 0;

 	/* set addressing mode to absolute to traverse the link list */
 	iwl_set_otp_access_absolute(trans);

 	/* checking for empty OTP or error */
 	if (iwl_is_otp_empty(trans))
 		return -EINVAL;

 	/*
 	 * start traverse link list
 	 * until reach the max number of OTP blocks
 	 * different devices have different number of OTP blocks
 	 */
 	do {
 		/* save current valid block address
 		 * check for more block on the link list
 		 */
 		valid_addr = next_link_addr;
 		next_link_addr = le16_to_cpu(link_value) * sizeof(u16);
 		IWL_DEBUG_EEPROM(trans->dev, "OTP blocks %d addr 0x%x\n",
 				 usedblocks, next_link_addr);
 		if (iwl_read_otp_word(trans, next_link_addr, &link_value))
 			return -EINVAL;
 		if (!link_value) {
 			/*
 			 * reach the end of link list, return success and
 			 * set address point to the starting address
 			 * of the image
 			 */
 			*validblockaddr = valid_addr;
 			/* skip first 2 bytes (link list pointer) */
 			*validblockaddr += 2;
 			return 0;
 		}
 		/* more in the link list, continue */
 		usedblocks++;
 	} while (usedblocks <= trans->trans_cfg->base_params->max_ll_items);

 	/* OTP has no valid blocks */
 	IWL_DEBUG_EEPROM(trans->dev, "OTP has no valid blocks\n");
 	return -EINVAL;
 }

 /*
  * iwl_read_eeprom - read EEPROM contents
  *
  * Load the EEPROM contents from adapter and return it
  * and its size.
  *
  * NOTE:  This routine uses the non-debug IO access functions.
  */
 int iwl_read_eeprom(struct iwl_trans *trans, u8 **eeprom, size_t *eeprom_size)
 {
 	__le16 *e;
 	u32 gp = iwl_read32(trans, CSR_EEPROM_GP);
 	int sz;
 	int ret;
 	u16 addr;
 	u16 validblockaddr = 0;
 	u16 cache_addr = 0;
 	int nvm_is_otp;

 	if (!eeprom || !eeprom_size)
 		return -EINVAL;

 	nvm_is_otp = iwl_nvm_is_otp(trans);
 	if (nvm_is_otp < 0)
 		return nvm_is_otp;

 	sz = trans->trans_cfg->base_params->eeprom_size;
 	IWL_DEBUG_EEPROM(trans->dev, "NVM size = %d\n", sz);

 	e = kmalloc(sz, GFP_KERNEL);
 	if (!e)
 		return -ENOMEM;

 	ret = iwl_eeprom_verify_signature(trans, nvm_is_otp);
 	if (ret < 0) {
 		IWL_ERR(trans, "EEPROM not found, EEPROM_GP=0x%08x\n", gp);
 		goto err_free;
 	}

 	/* Make sure driver (instead of uCode) is allowed to read EEPROM */
 	ret = iwl_eeprom_acquire_semaphore(trans);
 	if (ret < 0) {
 		IWL_ERR(trans, "Failed to acquire EEPROM semaphore.\n");
 		goto err_free;
 	}

 	if (nvm_is_otp) {
 		ret = iwl_init_otp_access(trans);
 		if (ret) {
 			IWL_ERR(trans, "Failed to initialize OTP access.\n");
 			goto err_unlock;
 		}

 		iwl_write32(trans, CSR_EEPROM_GP,
 			    iwl_read32(trans, CSR_EEPROM_GP) &
 			    ~CSR_EEPROM_GP_IF_OWNER_MSK);

 		iwl_set_bit(trans, CSR_OTP_GP_REG,
 			    CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK |
 			    CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK);
 		/* traversing the linked list if no shadow ram supported */
 		if (!trans->trans_cfg->base_params->shadow_ram_support) {
 			ret = iwl_find_otp_image(trans, &validblockaddr);
 			if (ret)
 				goto err_unlock;
 		}
 		for (addr = validblockaddr; addr < validblockaddr + sz;
 		     addr += sizeof(u16)) {
 			__le16 eeprom_data;

 			ret = iwl_read_otp_word(trans, addr, &eeprom_data);
 			if (ret)
 				goto err_unlock;
 			e[cache_addr / 2] = eeprom_data;
 			cache_addr += sizeof(u16);
 		}
 	} else {
 		/* eeprom is an array of 16bit values */
 		for (addr = 0; addr < sz; addr += sizeof(u16)) {
 			u32 r;

 			iwl_write32(trans, CSR_EEPROM_REG,
 				    CSR_EEPROM_REG_MSK_ADDR & (addr << 1));

 			ret = iwl_poll_bit(trans, CSR_EEPROM_REG,
 					   CSR_EEPROM_REG_READ_VALID_MSK,
 					   CSR_EEPROM_REG_READ_VALID_MSK,
 					   IWL_EEPROM_ACCESS_TIMEOUT);
 			if (ret < 0) {
 				IWL_ERR(trans,
 					"Time out reading EEPROM[%d]\n", addr);
 				goto err_unlock;
 			}
 			r = iwl_read32(trans, CSR_EEPROM_REG);
 			e[addr / 2] = cpu_to_le16(r >> 16);
 		}
 	}

 	IWL_DEBUG_EEPROM(trans->dev, "NVM Type: %s\n",
 			 nvm_is_otp ? "OTP" : "EEPROM");

 	iwl_eeprom_release_semaphore(trans);

 	*eeprom_size = sz;
 	*eeprom = (u8 *)e;
 	return 0;

  err_unlock:
 	iwl_eeprom_release_semaphore(trans);
  err_free:
 	kfree(e);

 	return ret;
 }
 IWL_EXPORT_SYMBOL(iwl_read_eeprom);
	// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
	/*
	* Copyright (C) 2005-2014, 2018-2019 Intel Corporation
	*/
	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/export.h>

	#include "iwl-drv.h"
	#include "iwl-debug.h"
	#include "iwl-eeprom-read.h"
	#include "iwl-io.h"
	#include "iwl-prph.h"
	#include "iwl-csr.h"

	/*
	* EEPROM access time values:
	*
	* Driver initiates EEPROM read by writing byte address << 1 to CSR_EEPROM_REG.
	* Driver then polls CSR_EEPROM_REG for CSR_EEPROM_REG_READ_VALID_MSK (0x1).
	* When polling, wait 10 uSec between polling loops, up to a maximum 5000 uSec.
	* Driver reads 16-bit value from bits 31-16 of CSR_EEPROM_REG.
	*/
	#define IWL_EEPROM_ACCESS_TIMEOUT 5000 /* uSec */

	#define IWL_EEPROM_SEM_TIMEOUT 10 /* microseconds */
	#define IWL_EEPROM_SEM_RETRY_LIMIT 1000 /* number of attempts (not time) */


	/*
	* The device's EEPROM semaphore prevents conflicts between driver and uCode
	* when accessing the EEPROM; each access is a series of pulses to/from the
	* EEPROM chip, not a single event, so even reads could conflict if they
	* weren't arbitrated by the semaphore.
	*/

	#define EEPROM_SEM_TIMEOUT 10 /* milliseconds */
	#define EEPROM_SEM_RETRY_LIMIT 1000 /* number of attempts (not time) */

	static int iwl_eeprom_acquire_semaphore(struct iwl_trans *trans)
	{
	u16 count;
	int ret;

	for (count = 0; count < EEPROM_SEM_RETRY_LIMIT; count++) {
	/* Request semaphore */
	iwl_set_bit(trans, CSR_HW_IF_CONFIG_REG,
	CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM);

	/* See if we got it */
	ret = iwl_poll_bit(trans, CSR_HW_IF_CONFIG_REG,
	CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM,
	CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM,
	EEPROM_SEM_TIMEOUT);
	if (ret >= 0) {
	IWL_DEBUG_EEPROM(trans->dev,
	"Acquired semaphore after %d tries.\n",
	count+1);
	return ret;
	}
	}

	return ret;
	}

	static void iwl_eeprom_release_semaphore(struct iwl_trans *trans)
	{
	iwl_clear_bit(trans, CSR_HW_IF_CONFIG_REG,
	CSR_HW_IF_CONFIG_REG_BIT_EEPROM_OWN_SEM);
	}

	static int iwl_eeprom_verify_signature(struct iwl_trans *trans, bool nvm_is_otp)
	{
	u32 gp = iwl_read32(trans, CSR_EEPROM_GP) & CSR_EEPROM_GP_VALID_MSK;

	IWL_DEBUG_EEPROM(trans->dev, "EEPROM signature=0x%08x\n", gp);

	switch (gp) {
	case CSR_EEPROM_GP_BAD_SIG_EEP_GOOD_SIG_OTP:
	if (!nvm_is_otp) {
	IWL_ERR(trans, "EEPROM with bad signature: 0x%08x\n",
	gp);
	return -ENOENT;
	}
	return 0;
	case CSR_EEPROM_GP_GOOD_SIG_EEP_LESS_THAN_4K:
	case CSR_EEPROM_GP_GOOD_SIG_EEP_MORE_THAN_4K:
	if (nvm_is_otp) {
	IWL_ERR(trans, "OTP with bad signature: 0x%08x\n", gp);
	return -ENOENT;
	}
	return 0;
	case CSR_EEPROM_GP_BAD_SIGNATURE_BOTH_EEP_AND_OTP:
	default:
	IWL_ERR(trans,
	"bad EEPROM/OTP signature, type=%s, EEPROM_GP=0x%08x\n",
	nvm_is_otp ? "OTP" : "EEPROM", gp);
	return -ENOENT;
	}
	}

	/******************************************************************************
	*
	* OTP related functions
	*
	******************************************************************************/

	static void iwl_set_otp_access_absolute(struct iwl_trans *trans)
	{
	iwl_read32(trans, CSR_OTP_GP_REG);

	iwl_clear_bit(trans, CSR_OTP_GP_REG,
	CSR_OTP_GP_REG_OTP_ACCESS_MODE);
	}

	static int iwl_nvm_is_otp(struct iwl_trans *trans)
	{
	u32 otpgp;

	/* OTP only valid for CP/PP and after */
	switch (trans->hw_rev & CSR_HW_REV_TYPE_MSK) {
	case CSR_HW_REV_TYPE_NONE:
	IWL_ERR(trans, "Unknown hardware type\n");
	return -EIO;
	case CSR_HW_REV_TYPE_5300:
	case CSR_HW_REV_TYPE_5350:
	case CSR_HW_REV_TYPE_5100:
	case CSR_HW_REV_TYPE_5150:
	return 0;
	default:
	otpgp = iwl_read32(trans, CSR_OTP_GP_REG);
	if (otpgp & CSR_OTP_GP_REG_DEVICE_SELECT)
	return 1;
	return 0;
	}
	}

	static int iwl_init_otp_access(struct iwl_trans *trans)
	{
	int ret;

	ret = iwl_finish_nic_init(trans, trans->trans_cfg);
	if (ret)
	return ret;

	iwl_set_bits_prph(trans, APMG_PS_CTRL_REG,
	APMG_PS_CTRL_VAL_RESET_REQ);
	udelay(5);
	iwl_clear_bits_prph(trans, APMG_PS_CTRL_REG,
	APMG_PS_CTRL_VAL_RESET_REQ);

	/*
	* CSR auto clock gate disable bit -
	* this is only applicable for HW with OTP shadow RAM
	*/
	if (trans->trans_cfg->base_params->shadow_ram_support)
	iwl_set_bit(trans, CSR_DBG_LINK_PWR_MGMT_REG,
	CSR_RESET_LINK_PWR_MGMT_DISABLED);

	return 0;
	}

	static int iwl_read_otp_word(struct iwl_trans *trans, u16 addr,
	__le16 *eeprom_data)
	{
	int ret = 0;
	u32 r;
	u32 otpgp;

	iwl_write32(trans, CSR_EEPROM_REG,
	CSR_EEPROM_REG_MSK_ADDR & (addr << 1));
	ret = iwl_poll_bit(trans, CSR_EEPROM_REG,
	CSR_EEPROM_REG_READ_VALID_MSK,
	CSR_EEPROM_REG_READ_VALID_MSK,
	IWL_EEPROM_ACCESS_TIMEOUT);
	if (ret < 0) {
	IWL_ERR(trans, "Time out reading OTP[%d]\n", addr);
	return ret;
	}
	r = iwl_read32(trans, CSR_EEPROM_REG);
	/* check for ECC errors: */
	otpgp = iwl_read32(trans, CSR_OTP_GP_REG);
	if (otpgp & CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK) {
	/* stop in this case */
	/* set the uncorrectable OTP ECC bit for acknowledgment */
	iwl_set_bit(trans, CSR_OTP_GP_REG,
	CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK);
	IWL_ERR(trans, "Uncorrectable OTP ECC error, abort OTP read\n");
	return -EINVAL;
	}
	if (otpgp & CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK) {
	/* continue in this case */
	/* set the correctable OTP ECC bit for acknowledgment */
	iwl_set_bit(trans, CSR_OTP_GP_REG,
	CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK);
	IWL_ERR(trans, "Correctable OTP ECC error, continue read\n");
	}
	*eeprom_data = cpu_to_le16(r >> 16);
	return 0;
	}

	/*
	* iwl_is_otp_empty: check for empty OTP
	*/
	static bool iwl_is_otp_empty(struct iwl_trans *trans)
	{
	u16 next_link_addr = 0;
	__le16 link_value;
	bool is_empty = false;

	/* locate the beginning of OTP link list */
	if (!iwl_read_otp_word(trans, next_link_addr, &link_value)) {
	if (!link_value) {
	IWL_ERR(trans, "OTP is empty\n");
	is_empty = true;
	}
	} else {
	IWL_ERR(trans, "Unable to read first block of OTP list.\n");
	is_empty = true;
	}

	return is_empty;
	}


	/*
	* iwl_find_otp_image: find EEPROM image in OTP
	* finding the OTP block that contains the EEPROM image.
	* the last valid block on the link list (the block _before_ the last block)
	* is the block we should read and used to configure the device.
	* If all the available OTP blocks are full, the last block will be the block
	* we should read and used to configure the device.
	* only perform this operation if shadow RAM is disabled
	*/
	static int iwl_find_otp_image(struct iwl_trans *trans,
	u16 *validblockaddr)
	{
	u16 next_link_addr = 0, valid_addr;
	__le16 link_value = 0;
	int usedblocks = 0;

	/* set addressing mode to absolute to traverse the link list */
	iwl_set_otp_access_absolute(trans);

	/* checking for empty OTP or error */
	if (iwl_is_otp_empty(trans))
	return -EINVAL;

	/*
	* start traverse link list
	* until reach the max number of OTP blocks
	* different devices have different number of OTP blocks
	*/
	do {
	/* save current valid block address
	* check for more block on the link list
	*/
	valid_addr = next_link_addr;
	next_link_addr = le16_to_cpu(link_value) * sizeof(u16);
	IWL_DEBUG_EEPROM(trans->dev, "OTP blocks %d addr 0x%x\n",
	usedblocks, next_link_addr);
	if (iwl_read_otp_word(trans, next_link_addr, &link_value))
	return -EINVAL;
	if (!link_value) {
	/*
	* reach the end of link list, return success and
	* set address point to the starting address
	* of the image
	*/
	*validblockaddr = valid_addr;
	/* skip first 2 bytes (link list pointer) */
	*validblockaddr += 2;
	return 0;
	}
	/* more in the link list, continue */
	usedblocks++;
	} while (usedblocks <= trans->trans_cfg->base_params->max_ll_items);

	/* OTP has no valid blocks */
	IWL_DEBUG_EEPROM(trans->dev, "OTP has no valid blocks\n");
	return -EINVAL;
	}

	/*
	* iwl_read_eeprom - read EEPROM contents
	*
	* Load the EEPROM contents from adapter and return it
	* and its size.
	*
	* NOTE: This routine uses the non-debug IO access functions.
	*/
	int iwl_read_eeprom(struct iwl_trans trans, u8 eeprom, size_t eeprom_size)
	{
	__le16 *e;
	u32 gp = iwl_read32(trans, CSR_EEPROM_GP);
	int sz;
	int ret;
	u16 addr;
	u16 validblockaddr = 0;
	u16 cache_addr = 0;
	int nvm_is_otp;

	if (!eeprom \|\| !eeprom_size)
	return -EINVAL;

	nvm_is_otp = iwl_nvm_is_otp(trans);
	if (nvm_is_otp < 0)
	return nvm_is_otp;

	sz = trans->trans_cfg->base_params->eeprom_size;
	IWL_DEBUG_EEPROM(trans->dev, "NVM size = %d\n", sz);

	e = kmalloc(sz, GFP_KERNEL);
	if (!e)
	return -ENOMEM;

	ret = iwl_eeprom_verify_signature(trans, nvm_is_otp);
	if (ret < 0) {
	IWL_ERR(trans, "EEPROM not found, EEPROM_GP=0x%08x\n", gp);
	goto err_free;
	}

	/* Make sure driver (instead of uCode) is allowed to read EEPROM */
	ret = iwl_eeprom_acquire_semaphore(trans);
	if (ret < 0) {
	IWL_ERR(trans, "Failed to acquire EEPROM semaphore.\n");
	goto err_free;
	}

	if (nvm_is_otp) {
	ret = iwl_init_otp_access(trans);
	if (ret) {
	IWL_ERR(trans, "Failed to initialize OTP access.\n");
	goto err_unlock;
	}

	iwl_write32(trans, CSR_EEPROM_GP,
	iwl_read32(trans, CSR_EEPROM_GP) &
	~CSR_EEPROM_GP_IF_OWNER_MSK);

	iwl_set_bit(trans, CSR_OTP_GP_REG,
	CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK \|
	CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK);
	/* traversing the linked list if no shadow ram supported */
	if (!trans->trans_cfg->base_params->shadow_ram_support) {
	ret = iwl_find_otp_image(trans, &validblockaddr);
	if (ret)
	goto err_unlock;
	}
	for (addr = validblockaddr; addr < validblockaddr + sz;
	addr += sizeof(u16)) {
	__le16 eeprom_data;

	ret = iwl_read_otp_word(trans, addr, &eeprom_data);
	if (ret)
	goto err_unlock;
	e[cache_addr / 2] = eeprom_data;
	cache_addr += sizeof(u16);
	}
	} else {
	/* eeprom is an array of 16bit values */
	for (addr = 0; addr < sz; addr += sizeof(u16)) {
	u32 r;

	iwl_write32(trans, CSR_EEPROM_REG,
	CSR_EEPROM_REG_MSK_ADDR & (addr << 1));

	ret = iwl_poll_bit(trans, CSR_EEPROM_REG,
	CSR_EEPROM_REG_READ_VALID_MSK,
	CSR_EEPROM_REG_READ_VALID_MSK,
	IWL_EEPROM_ACCESS_TIMEOUT);
	if (ret < 0) {
	IWL_ERR(trans,
	"Time out reading EEPROM[%d]\n", addr);
	goto err_unlock;
	}
	r = iwl_read32(trans, CSR_EEPROM_REG);
	e[addr / 2] = cpu_to_le16(r >> 16);
	}
	}

	IWL_DEBUG_EEPROM(trans->dev, "NVM Type: %s\n",
	nvm_is_otp ? "OTP" : "EEPROM");

	iwl_eeprom_release_semaphore(trans);

	*eeprom_size = sz;
	eeprom = (u8 )e;
	return 0;

	err_unlock:
	iwl_eeprom_release_semaphore(trans);
	err_free:
	kfree(e);

	return ret;
	}
	IWL_EXPORT_SYMBOL(iwl_read_eeprom);