iwlwifi: traverse linklist to find the valid OTP block

For devices using OTP memory, EEPROM image can start from
any one of the OTP blocks. If shadow RAM is disabled, we need to
traverse link list to find the last valid block, then start the EEPROM
image reading.

If OTP is not full, the valid block is the block _before_ the last block
on the link list; the last block on the link list is the empty block
ready for next OTP refresh/update.

If OTP is full, then the last block is the valid block to be used for
configure the device.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 150 insertions, 35 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-eeprom.c b/drivers/net/wireless/iwlwifi/iwl-eeprom.c
index ded63320a46..01b95e89009 100644
--- a/drivers/net/wireless/iwlwifi/iwl-eeprom.c
+++ b/drivers/net/wireless/iwlwifi/iwl-eeprom.c
@@ -152,6 +152,19 @@ int iwlcore_eeprom_verify_signature(struct iwl_priv *priv)
 }
 EXPORT_SYMBOL(iwlcore_eeprom_verify_signature);
 
+static void iwl_set_otp_access(struct iwl_priv *priv, enum iwl_access_mode mode)
+{
+	u32 otpgp;
+
+	otpgp = iwl_read32(priv, CSR_OTP_GP_REG);
+	if (mode == IWL_OTP_ACCESS_ABSOLUTE)
+		iwl_clear_bit(priv, CSR_OTP_GP_REG,
+				CSR_OTP_GP_REG_OTP_ACCESS_MODE);
+	else
+		iwl_set_bit(priv, CSR_OTP_GP_REG,
+				CSR_OTP_GP_REG_OTP_ACCESS_MODE);
+}
+
 static int iwlcore_get_nvm_type(struct iwl_priv *priv)
 {
 	u32 otpgp;
@@ -252,6 +265,124 @@ static int iwl_init_otp_access(struct iwl_priv *priv)
 	return ret;
 }
 
+static int iwl_read_otp_word(struct iwl_priv *priv, u16 addr, u16 *eeprom_data)
+{
+	int ret = 0;
+	u32 r;
+	u32 otpgp;
+
+	_iwl_write32(priv, CSR_EEPROM_REG,
+		     CSR_EEPROM_REG_MSK_ADDR & (addr << 1));
+	ret = iwl_poll_direct_bit(priv, CSR_EEPROM_REG,
+				  CSR_EEPROM_REG_READ_VALID_MSK,
+				  IWL_EEPROM_ACCESS_TIMEOUT);
+	if (ret < 0) {
+		IWL_ERR(priv, "Time out reading OTP[%d]\n", addr);
+		return ret;
+	}
+	r = _iwl_read_direct32(priv, CSR_EEPROM_REG);
+	/* check for ECC errors: */
+	otpgp = iwl_read32(priv, 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 acknowledgement */
+		iwl_set_bit(priv, CSR_OTP_GP_REG,
+			CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK);
+		IWL_ERR(priv, "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 acknowledgement */
+		iwl_set_bit(priv, CSR_OTP_GP_REG,
+				CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK);
+		IWL_ERR(priv, "Correctable OTP ECC error, continue read\n");
+	}
+	*eeprom_data = le16_to_cpu((__force __le16)(r >> 16));
+	return 0;
+}
+
+/*
+ * iwl_is_otp_empty: check for empty OTP
+ */
+static bool iwl_is_otp_empty(struct iwl_priv *priv)
+{
+	u16 next_link_addr = 0, link_value;
+	bool is_empty = false;
+
+	/* locate the beginning of OTP link list */
+	if (!iwl_read_otp_word(priv, next_link_addr, &link_value)) {
+		if (!link_value) {
+			IWL_ERR(priv, "OTP is empty\n");
+			is_empty = true;
+		}
+	} else {
+		IWL_ERR(priv, "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_priv *priv,
+					u16 *validblockaddr)
+{
+	u16 next_link_addr = 0, link_value = 0, valid_addr;
+	int ret = 0;
+	int usedblocks = 0;
+
+	/* set addressing mode to absolute to traverse the link list */
+	iwl_set_otp_access(priv, IWL_OTP_ACCESS_ABSOLUTE);
+
+	/* checking for empty OTP or error */
+	if (iwl_is_otp_empty(priv))
+		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 = link_value;
+		IWL_DEBUG_INFO(priv, "OTP blocks %d addr 0x%x\n",
+			       usedblocks, next_link_addr);
+		if (iwl_read_otp_word(priv, next_link_addr, &link_value))
+			return -EINVAL;
+		if (!link_value) {
+			/*
+			 * reach the end of link list,
+			 * set address point to the starting address
+			 * of the image
+			 */
+			goto done;
+		}
+		/* more in the link list, continue */
+		usedblocks++;
+	} while (usedblocks < priv->cfg->max_ll_items);
+	/* OTP full, use last block */
+	IWL_DEBUG_INFO(priv, "OTP is full, use last block\n");
+done:
+	*validblockaddr = valid_addr;
+	/* skip first 2 bytes (link list pointer) */
+	*validblockaddr += 2;
+	return ret;
+}
+
 /**
  * iwl_eeprom_init - read EEPROM contents
  *
@@ -266,15 +397,14 @@ int iwl_eeprom_init(struct iwl_priv *priv)
 	int sz;
 	int ret;
 	u16 addr;
-	u32 otpgp;
+	u16 validblockaddr = 0;
+	u16 cache_addr = 0;
 
 	priv->nvm_device_type = iwlcore_get_nvm_type(priv);
 	if (priv->nvm_device_type == -ENOENT)
 		return -ENOENT;
 	/* allocate eeprom */
-	if (priv->nvm_device_type == NVM_DEVICE_TYPE_OTP)
-		priv->cfg->eeprom_size =
-			OTP_BLOCK_SIZE * OTP_LOWER_BLOCKS_TOTAL;
+	IWL_DEBUG_INFO(priv, "NVM size = %d\n", priv->cfg->eeprom_size);
 	sz = priv->cfg->eeprom_size;
 	priv->eeprom = kzalloc(sz, GFP_KERNEL);
 	if (!priv->eeprom) {
@@ -302,46 +432,31 @@ int iwl_eeprom_init(struct iwl_priv *priv)
 		if (ret) {
 			IWL_ERR(priv, "Failed to initialize OTP access.\n");
 			ret = -ENOENT;
-			goto err;
+			goto done;
 		}
 		_iwl_write32(priv, CSR_EEPROM_GP,
 			     iwl_read32(priv, CSR_EEPROM_GP) &
 			     ~CSR_EEPROM_GP_IF_OWNER_MSK);
-		/* clear */
-		_iwl_write32(priv, CSR_OTP_GP_REG,
-			     iwl_read32(priv, CSR_OTP_GP_REG) |
+
+		iwl_set_bit(priv, CSR_OTP_GP_REG,
 			     CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK |
 			     CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK);
-
-		for (addr = 0; addr < sz; addr += sizeof(u16)) {
-			u32 r;
-
-			_iwl_write32(priv, CSR_EEPROM_REG,
-				     CSR_EEPROM_REG_MSK_ADDR & (addr << 1));
-
-			ret = iwl_poll_direct_bit(priv, CSR_EEPROM_REG,
-						  CSR_EEPROM_REG_READ_VALID_MSK,
-						  IWL_EEPROM_ACCESS_TIMEOUT);
-			if (ret < 0) {
-				IWL_ERR(priv, "Time out reading OTP[%d]\n", addr);
+		/* traversing the linked list if no shadow ram supported */
+		if (!priv->cfg->shadow_ram_support) {
+			if (iwl_find_otp_image(priv, &validblockaddr)) {
+				ret = -ENOENT;
 				goto done;
 			}
-			r = _iwl_read_direct32(priv, CSR_EEPROM_REG);
-			/* check for ECC errors: */
-			otpgp = iwl_read32(priv, CSR_OTP_GP_REG);
-			if (otpgp & CSR_OTP_GP_REG_ECC_UNCORR_STATUS_MSK) {
-				/* stop in this case */
-				IWL_ERR(priv, "Uncorrectable OTP ECC error, Abort OTP read\n");
+		}
+		for (addr = validblockaddr; addr < validblockaddr + sz;
+		     addr += sizeof(u16)) {
+			u16 eeprom_data;
+
+			ret = iwl_read_otp_word(priv, addr, &eeprom_data);
+			if (ret)
 				goto done;
-			}
-			if (otpgp & CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK) {
-				/* continue in this case */
-				_iwl_write32(priv, CSR_OTP_GP_REG,
-					     iwl_read32(priv, CSR_OTP_GP_REG) |
-					     CSR_OTP_GP_REG_ECC_CORR_STATUS_MSK);
-				IWL_ERR(priv, "Correctable OTP ECC error, continue read\n");
-			}
-			e[addr / 2] = le16_to_cpu((__force __le16)(r >> 16));
+			e[cache_addr / 2] = eeprom_data;
+			cache_addr += sizeof(u16);
 		}
 	} else {
 		/* eeprom is an array of 16bit values */