ice: discover and store size of available flash

When reading from the NVM using a flat address, it is useful to know the
upper bound on the size of the flash contents. This value is not stored
within the NVM.

We can determine the size by performing a bisection between upper and
lower bounds. It is known that the size cannot exceed 16 MB (offset of
0xFFFFFF).

Use a while loop to bisect the upper and lower bounds by reading one
byte at a time. On a failed read, lower the maximum bound. On
a successful read, increase the lower bound.

Save this as the flash_size in the ice_nvm_info structure that contains
data related to the NVM.

The size will be used in a future patch for implementing full NVM read
via ethtool's GEEPROM command.

The maximum possible size for the flash is bounded by the size limit for
the NVM AdminQ commands. Add a new macro, ICE_AQC_NVM_MAX_OFFSET, which
can be used to represent this upper bound.

Signed-off-by: Jacob Keller <[e-mail]>
Reviewed-by: Jesse Brandeburg <[e-mail]>
Tested-by: Andrew Bowers <[e-mail]>
Signed-off-by: Jeff Kirsher <[e-mail]>

drivers/net/ethernet/intel/ice/ice_adminq_cmd.h

···
  * NVM Update commands (indirect 0x0703)
  */
 struct ice_aqc_nvm {
+#define ICE_AQC_NVM_MAX_OFFSET		0xFFFFFF
 	__le16 offset_low;
 	u8 offset_high;
 	u8 cmd_flags;
···
 	ICE_AQ_RC_ENOMEM	= 9,  /* Out of memory */
 	ICE_AQ_RC_EBUSY		= 12, /* Device or resource busy */
 	ICE_AQ_RC_EEXIST	= 13, /* Object already exists */
+	ICE_AQ_RC_EINVAL	= 14, /* Invalid argument */
 	ICE_AQ_RC_ENOSPC	= 16, /* No space left or allocation failure */
 	ICE_AQ_RC_ENOSYS	= 17, /* Function not implemented */
 	ICE_AQ_RC_ENOSEC	= 24, /* Missing security manifest */

drivers/net/ethernet/intel/ice/ice_nvm.c

···
 
 	cmd = &desc.params.nvm;
 
-	/* In offset the highest byte must be zeroed. */
-	if (offset & 0xFF000000)
+	if (offset > ICE_AQC_NVM_MAX_OFFSET)
 		return ICE_ERR_PARAM;
 
 	ice_fill_dflt_direct_cmd_desc(&desc, ice_aqc_opc_nvm_read);
···
 }
 
 /**
+ * ice_discover_flash_size - Discover the available flash size.
+ * @hw: pointer to the HW struct
+ *
+ * The device flash could be up to 16MB in size. However, it is possible that
+ * the actual size is smaller. Use bisection to determine the accessible size
+ * of flash memory.
+ */
+static enum ice_status ice_discover_flash_size(struct ice_hw *hw)
+{
+	u32 min_size = 0, max_size = ICE_AQC_NVM_MAX_OFFSET + 1;
+	enum ice_status status;
+
+	status = ice_acquire_nvm(hw, ICE_RES_READ);
+	if (status)
+		return status;
+
+	while ((max_size - min_size) > 1) {
+		u32 offset = (max_size + min_size) / 2;
+		u32 len = 1;
+		u8 data;
+
+		status = ice_read_flat_nvm(hw, offset, &len, &data, false);
+		if (status == ICE_ERR_AQ_ERROR &&
+		    hw->adminq.sq_last_status == ICE_AQ_RC_EINVAL) {
+			ice_debug(hw, ICE_DBG_NVM,
+				  "%s: New upper bound of %u bytes\n",
+				  __func__, offset);
+			status = 0;
+			max_size = offset;
+		} else if (!status) {
+			ice_debug(hw, ICE_DBG_NVM,
+				  "%s: New lower bound of %u bytes\n",
+				  __func__, offset);
+			min_size = offset;
+		} else {
+			/* an unexpected error occurred */
+			goto err_read_flat_nvm;
+		}
+	}
+
+	ice_debug(hw, ICE_DBG_NVM,
+		  "Predicted flash size is %u bytes\n", max_size);
+
+	hw->nvm.flash_size = max_size;
+
+err_read_flat_nvm:
+	ice_release_nvm(hw);
+
+	return status;
+}
+
+/**
  * ice_init_nvm - initializes NVM setting
  * @hw: pointer to the HW struct
  *
···
 	}
 
 	nvm->eetrack = (eetrack_hi << 16) | eetrack_lo;
+
+	status = ice_discover_flash_size(hw);
+	if (status) {
+		ice_debug(hw, ICE_DBG_NVM,
+			  "NVM init error: failed to discover flash size.\n");
+		return status;
+	}
 
 	switch (hw->device_id) {
 	/* the following devices do not have boot_cfg_tlv yet */

drivers/net/ethernet/intel/ice/ice_type.h

···
 	struct ice_orom_info orom;	/* Option ROM version info */
 	u32 eetrack;			/* NVM data version */
 	u16 sr_words;			/* Shadow RAM size in words */
+	u32 flash_size;			/* Size of available flash in bytes */
 	u8 major_ver;			/* major version of NVM package */
 	u8 minor_ver;			/* minor version of dev starter */
 	u8 blank_nvm_mode;        /* is NVM empty (no FW present) */