interfaces.md

Hardware Interfaces

Signals

Referring to the Comportable guideline for peripheral device functionality, the module rv_core_ibex has the following hardware interfaces defined

• Primary Clock: clk_i
• Other Clocks: clk_edn_i, clk_esc_i, clk_otp_i
• Bus Device Interfaces (TL-UL): cfg_tl_d
• Bus Host Interfaces (TL-UL): corei_tl_h, cored_tl_h
• Peripheral Pins for Chip IO: none
• Interrupts: none

Inter-Module Signals

Port Name	Package::Struct	Type	Act	Width	Description
rst_cpu_n	logic	uni	req	1
ram_cfg	prim_ram_1p_pkg::ram_1p_cfg	uni	rcv	1
hart_id	logic	uni	rcv	32
boot_addr	logic	uni	rcv	32
irq_software	logic	uni	rcv	1
irq_timer	logic	uni	rcv	1
irq_external	logic	uni	rcv	1
esc_tx	prim_esc_pkg::esc_tx	uni	rcv	1
esc_rx	prim_esc_pkg::esc_rx	uni	req	1
debug_req	logic	uni	rcv	1
crash_dump	rv_core_ibex_pkg::cpu_crash_dump	uni	req	1
lc_cpu_en	lc_ctrl_pkg::lc_tx	uni	rcv	1
pwrmgr_cpu_en	lc_ctrl_pkg::lc_tx	uni	rcv	1
pwrmgr	rv_core_ibex_pkg::cpu_pwrmgr	uni	req	1
nmi_wdog	logic	uni	rcv	1
edn	edn_pkg::edn	req_rsp	req	1
icache_otp_key	otp_ctrl_pkg::sram_otp_key	req_rsp	req	1
fpga_info	logic	uni	rcv	32
corei_tl_h	tlul_pkg::tl	req_rsp	req	1
cored_tl_h	tlul_pkg::tl	req_rsp	req	1
cfg_tl_d	tlul_pkg::tl	req_rsp	rsp	1

Security Alerts

Alert Name	Description
fatal_sw_err	Software triggered alert for fatal faults
recov_sw_err	Software triggered Alert for recoverable faults
fatal_hw_err	Triggered when - Ibex raises alert_major_internal_o - Ibex raises alert_major_bus_o - A double fault is seen (Ibex raises double_fault_seen_o) - A bus integrity error is seen
recov_hw_err	Triggered when Ibex raises alert_minor_o

Security Countermeasures

Countermeasure ID	Description
RV_CORE_IBEX.BUS.INTEGRITY	End-to-end bus integrity scheme.
RV_CORE_IBEX.SCRAMBLE.KEY.SIDELOAD	The scrambling key for the icache is sideloaded from OTP and thus unreadable by SW.
RV_CORE_IBEX.CORE.DATA_REG_SW.SCA	Data independent timing.
RV_CORE_IBEX.PC.CTRL_FLOW.CONSISTENCY	Correct PC increment check.
RV_CORE_IBEX.CTRL_FLOW.UNPREDICTABLE	Randomized dummy instruction insertion.
RV_CORE_IBEX.DATA_REG_SW.INTEGRITY	Register file integrity checking. Note that whilst the core itself is duplicated (see LOGIC.SHADOW) the register file is not. Protection is provided by an ECC.
RV_CORE_IBEX.DATA_REG_SW.GLITCH_DETECT	This countermeasure augments DATA_REG_SW.INTEGRITY and checks for spurious write-enable signals on the register file by monitoring the one-hot0 property of the individual write-enable strobes.
RV_CORE_IBEX.LOGIC.SHADOW	Shadow core run in lockstep to crosscheck CPU behaviour. This provides broad protection for all assets with the Ibex core.
RV_CORE_IBEX.FETCH.CTRL.LC_GATED	Fetch enable so core execution can be halted.
RV_CORE_IBEX.EXCEPTION.CTRL_FLOW.LOCAL_ESC	A mechanism to detect and act on double faults. Local escalation shuts down the core when a double fault is seen.
RV_CORE_IBEX.EXCEPTION.CTRL_FLOW.GLOBAL_ESC	A mechanism to detect and act on double faults. Global escalation sends a fatal alert when a double fault is seen.
RV_CORE_IBEX.ICACHE.MEM.SCRAMBLE	ICache memory scrambling.
RV_CORE_IBEX.ICACHE.MEM.INTEGRITY	ICache memory integrity checking.

All ports and parameters of Ibex are exposed through this wrapper module, except for the instruction and data memory interfaces (signals starting with instr_ and data_). Refer to the Ibex documentation for a detailed description of these signals and parameters.

The instruction and data memory ports are exposed as TL-UL ports. The table below lists other signals and the TL-UL ports.

Signal	Direction	Type	Description
rst_cpu_n_o	output	logic	Outgoing indication to reset manager that the process has reset.
ram_cfg_i	input	prim_ram_1p_pkg::ram_1p_cfg_t	Incoming memory configuration that is technology dependent.
hart_id_i	input	logic [31:0]	Static Hard ID input signal.
boot_addr_i	input	logic [31:0]	Static boot address input signal.
fpga_info_i	input	logic [31:0]	Fpga info input signal, coming from a Xilinx USR_ACCESSE2 primitive for example.
irq_software_i	input	logic	Software interrupt input.
irq_timer_i	input	logic	Timer interrupt input.
irq_external_i	input	logic	External interrupt input.
debug_req_i	input	logic	Debug request from the debug module.
corei_tl_h_o	output	tlul_pkg::tl_h2d_t	Outgoing instruction tlul request.
corei_tl_h_i	input	tlul_pkg::tl_d2h_t	Incoming instruction tlul response.
cored_tl_h_o	output	tlul_pkg::tl_h2d_t	Outgoing data tlul request.
cored_tl_h_i	input	tlul_pkg::tl_d2h_t	Incoming data tlul response.
cfg_tl_d_i	output	tlul_pkg::tl_h2d_t	Outgoing data tlul request for peripheral registers.
cfg_tl_d_o	input	tlul_pkg::tl_d2h_t	Incoming data tlul response for peripheral registers.
alert_rx_i	input	prim_alert_pkg::alert_rx_t	Incoming alert response / ping.
alert_tx_o	output	prim_alert_pkg::alert_tx_t	Outgoing alert request.
esc_tx_i	input	prim_esc_pkg::esc_tx_t	Incoming escalation request / ping.
esc_rx_o	output	prim_esc_pkg::esc_rx_t	Outgoing escalation response.
nmi_wdog_i	input	logic	Incoming watchdog NMI bark.
crash_dump_o	output	ibex_pkg::crash_dump_t	Outgoing crash dump information to rstmgr.
cfg_tl_d_i	input	tlul_pkg::tl_h2d_t	Incoming configuration bus request.
cfg_tl_d_o	output	tlul_pkg::tl_d2h_t	Outgoing configuration bus response.
lc_cpu_en_i	input	lc_ctrl_pkg::lc_tx_t	CPU enable signal from life cycle controller.
pwrmgr_cpu_en_i	input	lc_ctrl_pkg::lc_tx_t	CPU enable signal from power manager.
pwrmgr_o	output	pwrmgr_pkg::cpu_pwrmgr_t	Low-power CPU status to power manager.
edn_i	input	edn_pkg::edn_rsp_t	Incoming entropy response from entropy distribution network.
edn_o	output	edn_pkg::edn_req_t	Outgoing entropy request to entropy distribution network.
icache_otp_key_i	input	otp_ctrl_pkg::sram_otp_key_rsp_t	Incoming scrambling key response from OTP to icache.
icache_otp_key_o	output	otp_ctrl_pkg::sram_otp_key_req_t	Outgoing scrambling key request from icache to OTP.

The PipeLine parameter can be used to configure the bus adapter pipelining.

• Setting PipeLine to 0 disables pipelining, which gives minimal latency between the bus and the core, at the cost of a combinatorial path into the core.
• Setting PipeLine to 1 introduces a pipelining FIFO between the core instruction/data interfaces and the bus. This setting increases the memory access latency, but improves timing.