xref: /openbmc/linux/drivers/net/wireless/intel/iwlwifi/iwl-eeprom-read.c (revision dde0a25d)

// 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);