FLASH_CTRL DV document


  • DV
    • Verify all flash_ctrl IP features by running dynamic simulations with a SV/UVM based testbench
    • Develop and run all tests based on the testplan below towards closing code and functional coverage on the IP and all of its sub-modules
  • FPV
    • Verify TileLink device protocol compliance with an SVA based testbench

Current status

Design features

For detailed information on flash_ctrl design features, please see the flash_ctrl HWIP technical specification. The design-under-test (DUT) wraps the flash_ctrl IP, flash_phy and the TLUL SRAM adapter that converts the incoming TL accesses from the from host (CPU) interface into flash requests. These modules are instantiated and connected to each other and to the rest of the design at the top level. For the IP level DV, we replicate the instantiations and connections in flash_ctrl_wrapper module maintained in DV, located at hw/ip/flash_ctrl/dv/tb/flash_ctrl_wrapper.sv. In future, we will consider having the wrapper maintained in the RTL area instead.

Testbench architecture

The flash_ctrl UVM DV testbench has been constructed based on the CIP testbench architecture.

Block diagram

Block diagram

Top level testbench

Top level testbench is located at hw/ip/flash_ctrl/dv/tb/tb.sv. It instantiates the flash_ctrl_wrapper. In addition, the testbench instantiates the following interfaces, connects them to the DUT and sets their handle into uvm_config_db:

Common DV utility components

The following utilities provide generic helper tasks and functions to perform activities that are common across the project:


flash_ctrl UVM environment instantiates a (already handled in CIP base env) tl_agent which provides the ability to drive and independently monitor random traffic via TL host interface into flash_ctrl device. There are two additional instances of the tl_agent.

  • Host interface to the flash_phy, to directly fetch the contents of the flash memory, bypassing the flash_ctrl.
  • Host interface to the prim registers.

The tl_agent monitor supplies partial TileLink request packets as well as completed TileLink response packets over the TLM analysis port for further processing within the flash_ctrl scoreboard.


The flash_ctrl RAL model is created with the ralgen FuseSoC generator script automatically when the simulation is at the build stage.

It can be created manually by invoking regtool:

Sequence cfg

An efficient way to develop test sequences is by providing some random variables that are used to configure the DUT / drive stimulus. The random variables are constrained using weights and knobs that can be controlled. These weights and knobs take on a “default” value that will result in the widest exploration of the design state space, when the test sequence is randomized and run as-is. To steer the randomization towards a particular distribution or to achieve interesting combinations of the random variables, the test sequence can be extended to create a specialized variant. In this extended sequence, nothing would need to be done, other than setting those weights and knobs appropriately. This helps increase the likelihood of hitting the design corners that would otherwise be difficult to achieve, while maximizing reuse.

This object aims to provide such run-time controls. An example of such a knob is num_en_mp_regions, which controls how many flash memory protection regions to configure, set to ‘all’ by default.

Env cfg

The flash_ctrl_env_cfg, environment configuration object provides access to the following elements:

  • Build-time controls to configure the UVM environment composition during the build_phase
  • Downstream agent configuration objects for ease of lookup from any environment component
    • This includes the tl_agent_cfg objects for both TL interfaces
  • All virtual interfaces that connect to the DUT listed above (retrieved from the uvm_config_db)
  • Sequence configuration object described above

All environment components contain a handle to an instance of this class (that was created in the test class via the parent dv_base_test). By housing all of the above, all pertinent information is more easily shared with all environment components.

Stimulus strategy

Test sequences

All test sequences reside in hw/ip/flash_ctrl/dv/env/seq_lib. The flash_ctrl_base_vseq virtual sequence is extended from cip_base_vseq and serves as a starting point. All test sequences are extended from flash_ctrl_base_vseq. It provides commonly used handles, variables, functions and tasks that the test sequences can simple use / call. Some of the most commonly used tasks / functions are as follows: From hw/ip/flash_ctrl/dv/env/seq/flash_ctrl_base_vseq.sv,

  • reset_flash Reset flash controller and initialize flash device using back door interface.
  • flash_ctrl_start_op Start operation on the flash controller
  • flash_ctrl_write Send data to prog_fifo. This task is used for program operation from controller combined with flash_ctrl_start_op.
  • flash_ctrl_read Read data from rd_fifo. This task is used for read operation from controller combined with flash_ctrl_start_op.
  • wait_flash_op_done Polling op_status until op_status.done is set.
  • do_direct_read Task to read flash from the host interface. Transaction size is 4 byte per transaction.
  • flash_ctrl_intr_read Task to program flash with interrupt mode.
  • flash_ctrl_intr_write Task to read flash with interrupt mode.
  • send_rma_req Task to initiate rma request. Once rma started, task polls rma ack until it completes.

Functional coverage

To ensure high quality constrained random stimulus, it is necessary to develop a functional coverage model. The following covergroups have been developed to prove that the test intent has been adequately met: hw/ip/flash_ctrl/dv/env/flash_ctrl_env_cov.sv

  • control_cg Collects operation types, partition and cross coverage of both.
  • erase_susp_cg Check if request of erase suspension occurred.
  • msgfifo_level_cg Covers all possible fifo status to generate interrupt for read / program.
  • rd_buff_evict_cg Check sequence of operation to trigger read eviction.
  • eviction_cg Check whether eviction happens at all 4 caches with write / erase operation. Also check each address belongs to randomly enabled scramble and ecc.
  • error_cg Check errors defined in error code registers.

Self-checking strategy


The flash_ctrl_scoreboard is primarily used for csr transaction integrity. Test bench also maintains a reference memory model (associative array) per partition. The reference model is updated on each operation and used for expected partition values at the end of test check. Given large memory size (mega bytes), maintaining an associative array per operation until the end of the test causes huge simulation overhead. Also, this model is not suitable for read only test, same address write test, descramble tests and error injection test for ecc. To address such issues, on-the-fly method is also used on top of legacy test component. In on-the-fly test mode, test does not rely on reference memory mode. Instead, it creates reference data for each operation. For the program(write) operation, rtl output is collected from flash phy interface and compared with each operation’s pre calculated write data. For the read operation, the expected data is written via memory backdoor interface, read back, and compared. The flash_ctrl_otf_scoreboard is used for on-the-fly mode flash transaction integrity check, while flash_ctrl_scoreboard is still used for csr transaction integrity check. Since there is still uncovered logic within the model before data reaches the actual device, we add extra scoreboard to check that path and call it last mile scoreboard. The last mile scoreboard is added to compensate on-the-fly model. For the write transaction, on-the-fly model collects rtl data at the boundary of the controller and flash model.


  • TLUL assertions: The hw/ip/flash_ctrl/dv/sva/flash_ctrl_bind.sv binds the tlul_assert assertions to the IP to ensure TileLink interface protocol compliance.
  • Unknown checks on DUT outputs: The RTL has assertions to ensure all outputs are initialized to known values after coming out of reset.

Global types and methods

All common types and methods defined at the package level can be found in flash_ctrl_env_pkg. Some of them in use are:

** types and enums
// Interrupt enums
  typedef enum int {
    FlashCtrlIntrProgEmpty = 0,
    FlashCtrlIntrProgLvl   = 1,
    FlashCtrlIntrRdFull    = 2,
    FlashCtrlIntrRdLvl     = 3,
    FlashCtrlIntrOpDone    = 4,
    FlashCtrlIntrErr       = 5,
    NumFlashCtrlIntr       = 6
  } flash_ctrl_intr_e;

// Flash initialization mode
  typedef enum {
    FlashMemInitCustom,     // Initialize flash (via bkdr) with custom data set.
    FlashMemInitSet,        // Initialize with all 1s.
    FlashMemInitClear,      // Initialize with all 0s.
    FlashMemInitRandomize,  // Initialize with random data.
    FlashMemInitInvalidate, // Initialize with Xs.
    FlashMemInitEccMode     // Flash init for ecc_mode
  } flash_mem_init_e;

// Ecc test mode
  typedef enum {
    FlashEccDisabled,    // No ecc enable
    FlashEccEnabled,     // Ecc enable but no error injection
    FlashSerrTestMode,   // Ecc enable and single bit error injection
    FlashDerrTestMode,   // Ecc enable and double bit error injection
    FlashIerrTestMode    // Ecc enable and integrity error injection
  } ecc_mode_e;

// 4-states flash data type
typedef logic [TL_DW-1:0] data_4s_t;
// flash address type
typedef bit [TL_AW-1:0] addr_t;
// Queue of 4-states data words
typedef data_4s_t data_q_t[$];
// Flash op struct
typedef struct packed {
    flash_dv_part_e  partition;   // data or one of the info partitions
    flash_erase_e    erase_type;  // erase page or the whole bank
    flash_op_e       op;          // read / program or erase
    flash_prog_sel_e prog_sel;    // program select
    uint             num_words;   // number of words to read or program (TL_DW)
    addr_t           addr;        // starting addr for the op
    // addres for the ctrl interface per bank, 18:0
    bit [flash_ctrl_pkg::BusAddrByteW-2:0] otf_addr;
  } flash_op_t;

Building and running tests

We are using our in-house developed regression tool for building and running our tests and regressions. Please take a look at the link for detailed information on the usage, capabilities, features and known issues. Here’s how to run a smoke test:

$ cd $REPO_TOP
$ ./util/dvsim/dvsim.py hw/ip/flash_ctrl/dv/flash_ctrl_sim_cfg.hjson -i flash_ctrl_smoke



Stage Name Tests Description
V1 smoke flash_ctrl_smoke

Randomly read, program or erase (page or a bank) a randomized chunk of flash memory. Only the data partition is accessed. No extra features enabled. Flash memory is invalidated and the targeted chunk is initialized with random data for reads and all 1s for writes. Interrupts are not enabled, Completion is ascertained through polling. The success of each operation is verified via backdoor.

V1 smoke_hw flash_ctrl_smoke_hw

Perform host direct read on the single page of Data partition. First Flash memory is initialized with random values and then it is being read directly by Host interface. Finally, backdoor read is used for checking read data.

V1 csr_hw_reset flash_ctrl_csr_hw_reset

Verify the reset values as indicated in the RAL specification.

  • Write all CSRs with a random value.
  • Apply reset to the DUT as well as the RAL model.
  • Read each CSR and compare it against the reset value. it is mandatory to replicate this test for each reset that affects all or a subset of the CSRs.
  • It is mandatory to run this test for all available interfaces the CSRs are accessible from.
  • Shuffle the list of CSRs first to remove the effect of ordering.
V1 csr_rw flash_ctrl_csr_rw

Verify accessibility of CSRs as indicated in the RAL specification.

  • Loop through each CSR to write it with a random value.
  • Read the CSR back and check for correctness while adhering to its access policies.
  • It is mandatory to run this test for all available interfaces the CSRs are accessible from.
  • Shuffle the list of CSRs first to remove the effect of ordering.
V1 csr_bit_bash flash_ctrl_csr_bit_bash

Verify no aliasing within individual bits of a CSR.

  • Walk a 1 through each CSR by flipping 1 bit at a time.
  • Read the CSR back and check for correctness while adhering to its access policies.
  • This verify that writing a specific bit within the CSR did not affect any of the other bits.
  • It is mandatory to run this test for all available interfaces the CSRs are accessible from.
  • Shuffle the list of CSRs first to remove the effect of ordering.
V1 csr_aliasing flash_ctrl_csr_aliasing

Verify no aliasing within the CSR address space.

  • Loop through each CSR to write it with a random value
  • Shuffle and read ALL CSRs back.
  • All CSRs except for the one that was written in this iteration should read back the previous value.
  • The CSR that was written in this iteration is checked for correctness while adhering to its access policies.
  • It is mandatory to run this test for all available interfaces the CSRs are accessible from.
  • Shuffle the list of CSRs first to remove the effect of ordering.
V1 csr_mem_rw_with_rand_reset flash_ctrl_csr_mem_rw_with_rand_reset

Verify random reset during CSR/memory access.

  • Run csr_rw sequence to randomly access CSRs
  • If memory exists, run mem_partial_access in parallel with csr_rw
  • Randomly issue reset and then use hw_reset sequence to check all CSRs are reset to default value
  • It is mandatory to run this test for all available interfaces the CSRs are accessible from.
V1 regwen_csr_and_corresponding_lockable_csrflash_ctrl_csr_rw

Verify regwen CSR and its corresponding lockable CSRs.

  • Randomly access all CSRs
  • Test when regwen CSR is set, its corresponding lockable CSRs become read-only registers


  • If regwen CSR is HW read-only, this feature can be fully tested by common CSR tests - csr_rw and csr_aliasing.
  • If regwen CSR is HW updated, a separate test should be created to test it.

This is only applicable if the block contains regwen and locakable CSRs.

V1 mem_walk flash_ctrl_mem_walk

Verify accessibility of all memories in the design.

  • Run the standard UVM mem walk sequence on all memories in the RAL model.
  • It is mandatory to run this test from all available interfaces the memories are accessible from.
V1 mem_partial_access flash_ctrl_mem_partial_access

Verify partial-accessibility of all memories in the design.

  • Do partial reads and writes into the memories and verify the outcome for correctness.
  • Also test outstanding access on memories
V2 sw_op flash_ctrl_sw_op

Perform flash protocol controller read, program and erase on the single page of one bank within Data partition. Finally perform read on same location in order to test if previous operation was done successfully.

V2 host_read_direct flash_ctrl_host_dir_rd

Perform back-to-back direct reads via Host in order to test bandwidth of hardware host interface. In addition, perform stalls to test pipeline structure. Enable scramble to test pipeline structure.

V2 rma_hw_if flash_ctrl_hw_rma

Perform RMA entry requests and check afterwards that the software has no access to the Flash. After RMA entry, verify that the content of the flash is wiped out.

V2 host_controller_arb flash_ctrl_host_ctrl_arb

Perform operations via the Flash Software Interface, and at the same time invoke a Hardware RMA operation. This verifies the arbitration within the Flash Protocol Controller. The arbiter should allow any outstanding Software operations to complete before the RMA starts. When the RMA completes the RMA FSM remains in its final state until Reset and software access is blocked.

V2 erase_suspend flash_ctrl_erase_suspend

Perform erase suspend when erase is ongoing and also when erase is not ongoing. Check if request is immediately cleared in case when no erase is ongoing. Check if request is cleared in case when suspend is handled. Read affected bank in order to verify erase suspension feature.

V2 full_memory_access flash_ctrl_full_mem_access

Entire memory is accessed by Controller and directly by Host. In addition, Data partitions can be directly read by Software(Flash controller) and hardware hosts, while Info partitions can be read only by the Flash controller.

V2 rd_buff_eviction flash_ctrl_rd_buff_evict

Perform following sequences of operations: read/program/read and read/erase/read in order to test read buffer eviction properly. Read should be executed by both Software and Host interface. All combinations should be tested. Covergroup for this hazardous behavior is rd_buff_evict_cg.

V2 rd_buff_eviction_w_ecc flash_ctrl_rw_evict

Run read eviction test with multiple memory protection configs. Each config should enable read but randomize all other fields including scramble and ecc enable.

V2 host_arb flash_ctrl_phy_arb

Test arbitration within Flash Physical Controller by reading from both interfaces at the same time. Perform continuously direct read data from host interface and at the same time, perform all operations READ/PROGRAM/ERASE from the flash controller is in progress. Perform parallel operations at addresses of different banks and also on same bank. Expect that operations are successfully executed.

V2 host_interleave flash_ctrl_phy_arb

At same time, perform two read operations and the same time via host and via controller. At same time, perform read operation via host and program operation via controller. Perform mentioned parallel operations at different addresses and on the same address. Expect that operations are successfully executed.

V2 memory_protection flash_ctrl_mp_regions

Perform READ/ PROGRAM/ ERASE operations over protected regions and pages of data and info partitions. Use set and reset values of corresponding read, program and erase enable bits. Test boundary values of regions. Test overlap of regions in which lower region wins arbitration.

V2 fetch_code flash_ctrl_fetch_code

Verify the Code Fetch Feature. Reads for instructions via the Hardware Interface are allowed if a specific value is written to the EXEC csr.

V2 all_partitions flash_ctrl_rand_ops

Sanity + both, legal data and info partitions are accessed. In future, support for multiple info partitions may be added - those will be covered as well.

V2 error_mp flash_ctrl_error_mp

Perform accesses in order to provoke memory permission errors. Test the Software interface (Erase, Program, Read). Related covergroup is sw_error_cg.

V2 error_prog_win flash_ctrl_error_prog_win

Perform accesses in order to provoke the 'program resolution' error. Test via the Software interface. Related covergroup is sw_error_cg.

V2 error_prog_type flash_ctrl_error_prog_type

Perform accesses in order to provoke the 'program type' error. Test via the Software interface. Related covergroup is sw_error_cg.

V2 read_write_overflow flash_ctrl_oversize_error

Send following error transactions with normal traffic and see any catastrophic event happens.

  • Program flash size longer than 64 bytes. This wil cause prog_win_err.
  • Read flash from controller without settting start op.
  • Issue rd_fifo read more thatn CONTROL.NUM field value. Both will cause d_error in tlul response. Each transaction is terminated gracefully and should not cause data path lock up. Also error status should be check per each transaction.
V2 flash_ctrl_disable flash_ctrl_disable

Set flash ctrl disable by hw (lc_escalate_en = On) or sw (flash_ctrl.dis = MuBi4True). And try to access flash ctrl and check the access attempt to be failed.

V2 flash_ctrl_connect flash_ctrl_connect

Check jtag input / output ports connectivity with lc_nvm_debug_en. Connections are set only when lc_nvm_debug_en = On.

V2 stress_all flash_ctrl_stress_all
  • combine above sequences in one test to run sequentially, except csr sequence
  • randomly add reset between each sequence
V2 secret_partition flash_ctrl_hw_sec_otp

Verify the secret information partitions. Accessibility is controlled by the Life Cycle Controller Seeds are read upon flash controller initialization and sent to the Key Manager, additionally verify that scramble Keys are Read from the OTP and sent into the Flash Ctlr. Also erify that programmed Secret Partitions retain their values through a Reset Cycle.

V2 isolation_partition flash_ctrl_hw_rma

Verify the isolated information partitions. Accessablity is controlled by Life Cycle Controller. Verify Partition can be erase, written and programmed, with HW control, and wipes after an RMA.

V2 interrupts flash_ctrl_intr_rd

Perform accesses in order to raise all interrupts given in register map. Check behaviour of Interrupt Enable and Status Registers.

V2 invalid_op flash_ctrl_invalid_op

Send invalid command in order to check that it does not affect memory content. Check that recovery alert is triggered.

V2 mid_op_rst flash_ctrl_mid_op_rst

Flash middle operation reset test. Send reset via power ready signal in the middle of operation program, read, erase and erase suspend.

V2 double_bit_err flash_ctrl_read_word_sweep_derr

Run read / write test and inject double bit error randomly for read transactions -- both direct and controller read. Check op_status.err and err_code.rd_err are asserted for ctrl read and tlul response error for host read. Check fatal alert is asserted for reliability ecc errors (double bits) and integrity ECC errors.

V2 single_bit_err flash_ctrl_read_word_sweep_serr

Run read only or read write test with randomly injected single bit error. All single bit error should be corrected and all read data should be matched with expected written value.

V2 singlebit_err_counter flash_ctrl_serr_counter

Run read / write test and inject single bit error randomly for read transactions. - both direct and controller read - Adjust error injection ratio s.t. counter is not saturated. Compare counter values for both bank with expected counter values.

V2 singlebit_err_address flash_ctrl_serr_address

Run read / write test and inject a single bit error randomly either direct or controller read. Once error is injected a certain transaction, wait for the transaction to be completed and compare ecc_single_err_addr register with the expected value. Do this for multiple rounds for both banks.

V2 scramble flash_ctrl_wo

Enable scrambling, along with randomized scramble keys. Program a fresh chunk of memory and read back (both, via controller and host) to ensure data integrity. On program, verify via backdoor scrambling was done on the raw data correctly. When reading via host, read the same memory via host multiple times back-to-back and ensure the timing is correct (subsequent reads should be faster). When scrambling is not enabled, ensure that the raw data is written and read back.

V2 filesystem_support flash_ctrl_fs_sup

Enable ECC and disable scrambling for all regions. Initialize flash with erased state (FlashMemInitSet). Execute random number of writes without writing the same location twice. Record all write locations(Minimum resolution of location is 8bytes). After that, execute write and read back test for random page and check

  • If the locations are in the written record, write data should be all 0 and readback data should match with the written data.
  • If the locations are not in the written record, write data should be random and readback data should match with the written data.
V2 rma_write_process_error flash_ctrl_rma_err

Verify error handling process duing the rma wipe process. In normal rma process, inject bit error at the write path (tb.dut.u_eflash.gen_flash_cores[0].u_core.gen_prog_data.u_prog.pack_data). This should make debug_state to flash_ctrl_env_pkg::FlashLcIvalid and fatal error (std_fault_status.lcmgr_err) should be triggered.

V2 alert_test flash_ctrl_alert_test

Verify common alert_test CSR that allows SW to mock-inject alert requests.

  • Enable a random set of alert requests by writing random value to alert_test CSR.
  • Check each alert_tx.alert_p pin to verify that only the requested alerts are triggered.
  • During alert_handshakes, write alert_test CSR again to verify that: If alert_test writes to current ongoing alert handshake, the alert_test request will be ignored. If alert_test writes to current idle alert handshake, a new alert_handshake should be triggered.
  • Wait for the alert handshakes to finish and verify alert_tx.alert_p pins all sets back to 0.
  • Repeat the above steps a bunch of times.
V2 intr_test flash_ctrl_intr_test

Verify common intr_test CSRs that allows SW to mock-inject interrupts.

  • Enable a random set of interrupts by writing random value(s) to intr_enable CSR(s).
  • Randomly "turn on" interrupts by writing random value(s) to intr_test CSR(s).
  • Read all intr_state CSR(s) back to verify that it reflects the same value as what was written to the corresponding intr_test CSR.
  • Check the cfg.intr_vif pins to verify that only the interrupts that were enabled and turned on are set.
  • Clear a random set of interrupts by writing a randomly value to intr_state CSR(s).
  • Repeat the above steps a bunch of times.
V2 tl_d_oob_addr_access flash_ctrl_tl_errors

Access out of bounds address and verify correctness of response / behavior

V2 tl_d_illegal_access flash_ctrl_tl_errors

Drive unsupported requests via TL interface and verify correctness of response / behavior. Below error cases are tested bases on the [TLUL spec]({{< relref "hw/ip/tlul/doc/_index.md#explicit-error-cases" >}})

  • TL-UL protocol error cases
    • invalid opcode
    • some mask bits not set when opcode is PutFullData
    • mask does not match the transfer size, e.g. a_address = 0x00, a_size = 0, a_mask = 'b0010
    • mask and address misaligned, e.g. a_address = 0x01, a_mask = 'b0001
    • address and size aren't aligned, e.g. a_address = 0x01, a_size != 0
    • size is greater than 2
  • OpenTitan defined error cases
    • access unmapped address, expect d_error = 1 when devmode_i == 1
    • write a CSR with unaligned address, e.g. a_address[1:0] != 0
    • write a CSR less than its width, e.g. when CSR is 2 bytes wide, only write 1 byte
    • write a memory with a_mask != '1 when it doesn't support partial accesses
    • read a WO (write-only) memory
    • write a RO (read-only) memory
    • write with instr_type = True
V2 tl_d_outstanding_access flash_ctrl_csr_hw_reset

Drive back-to-back requests without waiting for response to ensure there is one transaction outstanding within the TL device. Also, verify one outstanding when back- to-back accesses are made to the same address.

V2 tl_d_partial_access flash_ctrl_csr_hw_reset

Access CSR with one or more bytes of data. For read, expect to return all word value of the CSR. For write, enabling bytes should cover all CSR valid fields.

V2S shadow_reg_update_error flash_ctrl_shadow_reg_errors

Verify shadowed registers' update error.

  • Randomly pick a shadowed register in the DUT.
  • Write it twice with different values.
  • Verify that the update error alert is triggered and the register value remains unchanged.
  • Verify the update_error status register field is set to 1.
  • Repeat the above steps a bunch of times.
V2S shadow_reg_read_clear_staged_value flash_ctrl_shadow_reg_errors

Verify reading a shadowed register will clear its staged value.

  • Randomly pick a shadowed register in the DUT.
  • Write it once and read it back to clear the staged value.
  • Then write it twice with the same new value (but different from the previous step).
  • Read it back to verify the new value and ensure that the update error alert did not trigger.
  • Verify the update_error status register field remains the same value.
  • Repeat the above steps a bunch of times.
V2S shadow_reg_storage_error flash_ctrl_shadow_reg_errors

Verify shadowed registers' storage error.

  • Randomly pick a shadowed register in the DUT.
  • Backdoor write to shadowed or committed flops to create a storage fatal alert.
  • Check if fatal alert continuously fires until reset.
  • Verify that all other frontdoor write attempts are blocked during the storage error.
  • Verify that storage_error status register field is set to 1.
  • Reset the DUT.
  • Read all CSRs to ensure the DUT is properly reset.
  • Repeat the above steps a bunch of times.
V2S shadowed_reset_glitch flash_ctrl_shadow_reg_errors

Verify toggle shadowed_rst_n pin can trigger storage error.

  • Randomly drive shadowed_rst_n pin to low or rst_n pin to low.
  • check if any registers have been written before the reset. If so check if storage error fatal alert is triggered.
  • Check status register.
  • Drive shadowed_rst_n pin or rst_n pin back to high.
  • If fatal alert is triggered, reset the DUT.
  • Read all CSRs to ensure the DUT is properly reset.
  • Repeat the above steps a bunch of times.
V2S shadow_reg_update_error_with_csr_rw flash_ctrl_shadow_reg_errors_with_csr_rw

Run shadow_reg_update_error sequence in parallel with csr_rw sequence.

  • Randomly select one of the above sequences.
  • Apply csr_rw sequence in parallel but disable the csr_access_abort to ensure all shadowed registers' write/read to be executed without aborting.
  • Repeat the above steps a bunch of times.
V2S tl_intg_err flash_ctrl_tl_intg_err

Verify that the data integrity check violation generates an alert.

  • Randomly inject errors on the control, data, or the ECC bits during CSR accesses. Verify that triggers the correct fatal alert.
  • Inject a fault at the onehot check in u_reg.u_prim_reg_we_check and verify the corresponding fatal alert occurs
V2S sec_cm_reg_bus_integrity flash_ctrl_tl_intg_err

Verify the countermeasure(s) REG.BUS.INTEGRITY. This entry is covered by tl_access_test (hw/dv/tools/dvsim/tests/tl_access_tests.hjson)

V2S sec_cm_host_bus_integrity flash_ctrl_tl_intg_err

Verify the countermeasure(s) HOST.BUS.INTEGRITY. This entry is covered by tl_access_test (hw/dv/tools/dvsim/tests/tl_access_tests.hjson)

V2S sec_cm_mem_bus_integrity flash_ctrl_rd_intg

Verify the countermeasure(s) MEM.BUS.INTEGRITY. For read path, inject error to tb.dut.u_eflash.gen_flash_cores[*].u_core.u_rd.gen_bufs[0]. u_rd_buf.data_i read data error will trigger fault_status.phy_storage_err and err_code.rd_err. For write path, inject error to tb.dut.u_prog_fifo.wdata_i This will trigger fatal_std_err.prog_intg_err and err_code.prog_err

V2S sec_cm_scramble_key_sideload flash_ctrl_smoke

Verify the countermeasure(s) SCRAMBLE.KEY.SIDELOAD. The scrambling key is sideloaded from OTP and thus unreadable by SW. TBD

V2S sec_cm_lc_ctrl_intersig_mubi flash_ctrl_sec_info_access

Verify the countermeasure(s) LC_CTRL.INTERSIG.MUBI.

  • Creator info partition can be read, written, erased when lc_creator_seed_sw_rw_en is true. Owner info partition can be read, written, erased when lc_owner_seed_sw_rw_en is true. Isolated info partition can be written whwen lc_iso_part_sw_wr_en is true, and can be read when lc_iso_part_sw_rd_en is true. Run test for each partition and check whether each partition can be accessed only when each lc_ctrl input is valid. If lc_ctrl inputs are invalid, the access to the secret info region will trigger recoverable fatal alert.
  • lc_seed_hw_rd_en is covered by flash_ctrl_otp_reset test.
  • lc_escalate_en_i is covered by flash_ctrl_disable test. See 'flash_ctrl_disable` from the flash_ctrl_testpan.hjson
  • lc_nvm_debug_en_i is covered by flash_ctrl_connect. See 'flash_ctrl_connect' from the flash_ctrl_testplan.hjson
V2S sec_cm_ctrl_config_regwen flash_ctrl_config_regwen

Verify the countermeasure(s) CTRL.CONFIG.REGWEN.

V2S sec_cm_data_regions_config_regwen flash_ctrl_csr_rw

Verify the countermeasure(s) DATA_REGIONS.CONFIG.REGWEN.

V2S sec_cm_data_regions_config_shadow flash_ctrl_shadow_reg_errors

Verify the countermeasure(s) DATA_REGIONS.CONFIG.SHADOW.

V2S sec_cm_info_regions_config_regwen flash_ctrl_csr_rw

Verify the countermeasure(s) INFO_REGIONS.CONFIG.REGWEN.

V2S sec_cm_info_regions_config_shadow flash_ctrl_shadow_reg_errors

Verify the countermeasure(s) INFO_REGIONS.CONFIG.SHADOW.

V2S sec_cm_bank_config_regwen flash_ctrl_csr_rw

Verify the countermeasure(s) BANK.CONFIG.REGWEN.

V2S sec_cm_bank_config_shadow flash_ctrl_shadow_reg_errors

Verify the countermeasure(s) BANK.CONFIG.SHADOW.

V2S sec_cm_mem_ctrl_global_esc flash_ctrl_disable

Verify the countermeasure(s) MEM.CTRL.GLOBAL_ESC. Send a few flash access commands and disable flash access by setting lc_escalate_en to lc_ctrl_pkg::On. Check

  • Ctrl initiated traffic : mp error
  • Host initiated traffic : tlul errors
  • Outstanding traffic: Program or erase will be completed. Read will be dropped.
  • Debug state is changed to 'flash_ctrl_env_pkg::FlashLcDisabled' state
V2S sec_cm_mem_ctrl_local_esc flash_ctrl_rd_intg

Verify the countermeasure(s) MEM.CTRL.LOCAL_ESC. Send a few flash access commands and disable flash access by triggering std_fault. Check

  • Ctrl initiated traffic : mp error
  • Host initiated traffic : tlul errors
  • Outstanding traffic: Program or erase will be completed. Read will be dropped.
  • Debug state is changed to 'flash_ctrl_env_pkg::FlashLcDisabled' state
V2S sec_cm_mem_disable_config_mubi flash_ctrl_disable

Verify the countermeasure(s) MEM_DISABLE.CONFIG.MUBI.

V2S sec_cm_exec_config_redun flash_ctrl_fetch_code

Verify the countermeasure(s) EXEC.CONFIG.REDUN.

V2S sec_cm_mem_scramble flash_ctrl_rw

Verify the countermeasure(s) MEM.SCRAMBLE.

V2S sec_cm_mem_integrity flash_ctrl_rw_serr

Verify the countermeasure(s) MEM.INTEGRITY.

V2S sec_cm_rma_entry_mem_sec_wipe flash_ctrl_hw_rma

Verify the countermeasure(s) RMA_ENTRY.MEM.SEC_WIPE. RMA entry wipes flash memory with random data.

V2S sec_cm_ctrl_fsm_sparse flash_ctrl_sec_cm

Verify the countermeasure(s) CTRL.FSM.SPARSE. Error is injected by global test. Follwing state machines are in this category.

  • tb.dut.u_ctrl_arb.state_q : Error from this state machine will trigger std_fault_status.arb_fsm_err.
  • tb.dut.u_flash_hw_if.state_q, tb.dut.u_flash_hw_if.rma_state_q Error from these state machines will trigger std_fault_status.lcmgr_err.
V2S sec_cm_phy_fsm_sparse flash_ctrl_sec_cm

Verify the countermeasure(s) PHY.FSM.SPARSE. Error is injected by global test on tb.dut.u_eflash.gen_flash_cores[*].u_core.state_q. Error from this state machine will trigger std_fault_status.phy_fsm_err.

V2S sec_cm_phy_prog_fsm_sparse flash_ctrl_sec_cm

Verify the countermeasure(s) PHY_PROG.FSM.SPARSE. Error is injected by global test on tb.dut.u_eflash.gen_flash_cores[*].u_core.gen_prog_data.u_prog.state_q. Error from this state machine will trigger std_fault_status.phy_fsm_err.

V2S sec_cm_ctr_redun flash_ctrl_sec_cm

Verify the countermeasure(s) CTR.REDUN. Error is injected by global test. Follwing counters are in this category.

  • tb.dut.u_flash_hw_if.seed_cnt_q
  • tb.dut.u_flash_hw_if.addr_cnt_q
  • tb.dut.u_flash_hw_if.page_cnt
  • tb.dut.u_flash_hw_if.word_cnt
  • tb.dut.u_flash_hw_if.rma_wipe_idx Error from these counters will trigger std_fault_status.lcmgr_err.
V2S sec_cm_phy_arbiter_ctrl_redun flash_ctrl_phy_arb_redun

Verify the countermeasure(s) PHY_ARBITER.CTRL.REDUN.

The phy arbiter for controller and host is redundant. The arbiter has two instance underneath that are constantly compared to each other. tb.dut.u_eflash.gen_flash_cores[0].u_core.u_host_arb.gen_input_bufs[0].u_req_buf.out_o[1:0] tb.dut.u_eflash.gen_flash_cores[0].u_core.u_host_arb.gen_input_bufs[1].u_req_buf.out_o[1:0]

Make output of both mismatch and check fault_status.arb_err is triggered.

V2S sec_cm_phy_host_grant_ctrl_consistency flash_ctrl_phy_host_grant_err

Verify the countermeasure(s) PHY_HOST_GRANT.CTRL.CONSISTENCY.

A host transaction was granted to the muxed partition, this is illegal. @ tb.dut.u_eflash.gen_flash_cores[0].u_core.host_gnt, force tb.dut.u_eflash.gen_flash_cores[0].u_core.muxed_part = 1 and check fault_status.host_gnt_err.

V2S sec_cm_phy_ack_ctrl_consistency flash_ctrl_phy_ack_consistency

Verify the countermeasure(s) PHY_ACK.CTRL.CONSISTENCY.

Trigger tb.dut.u_eflash.gen_flash_cores[0].u_core.spurious_ack_o as follows: @ tb.dut.u_eflash.gen_flash_cores[0].u_core.ctrl_fsm_idle force tb.dut.u_eflash.gen_flash_cores[0].u_core.ctrl_rsp_vld = 1 or @ tb.dut.u_eflash.gen_flash_cores[0].u_core.host_outstanding[1:0] == 0 force tb.dut.u_eflash.gen_flash_cores[0].u_core.host_req_done_o = 1 Check fault_status.spurious_ack

V2S sec_cm_fifo_ctr_redun flash_ctrl_sec_cm

Verify the countermeasure(s) FIFO.CTR.REDUN. Error is injected by global test. Follwing fifos are in this category.

  • dut.u_to_rd_fifo,
  • dut.u_eflash.gen_flash_cores[*].u_core.u_rd.u_rsp_order_fifo,
  • dut.u_eflash.gen_flash_cores[*].u_core.u_rd.u_rd_storage Error from these fifos will trigger std_fault_status.fifo_err.
V3 robustness

Enable full randomization in order to fully stress DUT. Perform illegal accesses in order to gain robustness.

V3 stress_all_with_rand_reset flash_ctrl_stress_all_with_rand_reset

This test runs 3 parallel threads - stress_all, tl_errors and random reset. After reset is asserted, the test will read and check all valid CSR registers.


Name Description

Covers that all operations READ/PROGRAM/ERASE/UNKNOWN have been tested. Covers that ERASE operation is performed on a page and on entire bank. Covers data and info partitions selection. All valid combinations of the above will also be crossed.


Covers if request of erase suspension occured.


Covers eviction with mp_region_cfgs for data and info regions. Sample all 4 rd_buf status. When each buffer hazard is set, capture the address stored in the buffer. Then search from tb data base to see which region the address belong to. After that record the config value (scrambe_en and ecc_en) of the region. Use cross over buffer index, the operation to cause the eviction and the region config values.


Covers whether dut received valid or invalid key value from ral.exec register. Cross with tlul.instr_types.


Covers that all possible fifo statuses generate interrupts for operations READ/PROGRAM. Covers both boundary values 0 and 31. Also covers acceptable distributions within ranges.


Covers that all possible combinations for following sequences of operations READ/PROGRAM/READ and READ/ERASE/READ are executed. Software Interface can perform all three operations READ/PROGRAM/ERASE while Host Interface can perform direct READ.


Cover each lockable reg field with these 2 cases:

  • When regwen = 1, a different value is written to the lockable CSR field, and a read occurs after that.
  • When regwen = 0, a different value is written to the lockable CSR field, and a read occurs after that.

This is only applicable if the block contains regwen and locakable CSRs.


Cover rma operation is executed regardless of when flash_init started. flash_ctrl_hw_rma runs rma operation and flash init in parallel thread. In this test, sample rma state when flash init starts. If rma state is StRmaIdle, which means rma is not started. So it confirms rma start after flash init start. If rma state is [StRmaPageSel:StRmaInvalid], which mean rma is on going. So it confirms rma start before flash init start.


Cover all shadow register errors for each register field.

For all register fields within the shadowed register, this coverpoint covers the following errors:

  • Update error
  • Storage error

Covers following error scenarios given in Flash error code register:

  • op_err: Undefined operation.
  • mp_err: Flash access has encountered an access permission error.
  • rd_err: Flash read has an uncorrectable data error.
  • prog_err: Flash program has an error.
  • prog_win_err: Flash program has a window resolution error.
  • prog_type_err: Flash program selected unavailable type.
  • update_err: A shadow register encountered an update error.

Cover the following error cases on TL-UL bus:

  • TL-UL protocol error cases.
  • OpenTitan defined error cases, refer to testpoint tl_d_illegal_access.

Cover all kinds of integrity errors (command, data or both) and cover number of error bits on each integrity check.

Cover the kinds of integrity errors with byte enabled write on memory if applicable: Some memories store the integrity values. When there is a subword write, design re-calculate the integrity with full word data and update integrity in the memory. This coverage ensures that memory byte write has been issued and the related design logic has been verfied.