// SPDX-FileCopyrightText: 2020 Efabless Corporation // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // SPDX-License-Identifier: Apache-2.0 `default_nettype none /* *--------------------------------------------------------------------- * See gpio_control_block for description. This module is like * gpio_contro_block except that it has an additional two management- * Soc-facing pins, which are the out_enb line and the output line. * If the chip is configured for output with the oeb control * register = 1, then the oeb line is controlled by the additional * signal from the management SoC. If the oeb control register = 0, * then the output is disabled completely. The "io" line is input * only in this module. * *--------------------------------------------------------------------- */ /* *--------------------------------------------------------------------- * * This module instantiates a shift register chain that passes through * each gpio cell. These are connected end-to-end around the padframe * periphery. The purpose is to avoid a massive number of control * wires between the digital core and I/O, passing through the user area. * * See mprj_ctrl.v for the module that registers the data for each * I/O and drives the input to the shift register. * * Modified 7/24/2022 by Tim Edwards * Replaced the data delay with a negative edge-triggered flop * so that the serial data bit out from the module only changes on * the clock half cycle. This avoids the need to fine-tune the clock * skew between GPIO blocks. * * Modified 10/05/2022 by Tim Edwards * *--------------------------------------------------------------------- */ module gpio_control_block #( parameter PAD_CTRL_BITS = 13 ) ( `ifdef USE_POWER_PINS inout vccd, inout vssd, inout vccd1, inout vssd1, `endif // Power-on defaults input [PAD_CTRL_BITS-1:0] gpio_defaults, // Management Soc-facing signals input resetn, // Global reset, locally propagated output resetn_out, input serial_clock, // Global clock, locally propatated output serial_clock_out, input serial_load, // Register load strobe output serial_load_out, output mgmt_gpio_in, // Management from pad (input only) input mgmt_gpio_out, // Management to pad (output only) input mgmt_gpio_oeb, // Management to pad (output only) // Serial data chain for pad configuration input serial_data_in, output serial_data_out, // User-facing signals input user_gpio_out, // User space to pad input user_gpio_oeb, // Output enable (user) output user_gpio_in, // Pad to user space // Pad-facing signals (Pad GPIOv2) output pad_gpio_holdover, output pad_gpio_slow_sel, output pad_gpio_vtrip_sel, output pad_gpio_inenb, output pad_gpio_ib_mode_sel, output pad_gpio_ana_en, output pad_gpio_ana_sel, output pad_gpio_ana_pol, output [2:0] pad_gpio_dm, output pad_gpio_outenb, output pad_gpio_out, input pad_gpio_in, // to provide a way to automatically disable/enable output // from the outside with needing a conb cell output one, output zero ); /* Parameters defining the bit offset of each function in the chain */ localparam MGMT_EN = 0; localparam OEB = 1; localparam HLDH = 2; localparam INP_DIS = 3; localparam MOD_SEL = 4; localparam AN_EN = 5; localparam AN_SEL = 6; localparam AN_POL = 7; localparam SLOW = 8; localparam TRIP = 9; localparam DM = 10; /* Internally registered signals */ reg mgmt_ena; // Enable management SoC to access pad reg gpio_holdover; reg gpio_slow_sel; reg gpio_vtrip_sel; reg gpio_inenb; reg gpio_ib_mode_sel; reg gpio_outenb; reg [2:0] gpio_dm; reg gpio_ana_en; reg gpio_ana_sel; reg gpio_ana_pol; /* Derived output values */ wire pad_gpio_holdover; wire pad_gpio_slow_sel; wire pad_gpio_vtrip_sel; wire pad_gpio_inenb; wire pad_gpio_ib_mode_sel; wire pad_gpio_ana_en; wire pad_gpio_ana_sel; wire pad_gpio_ana_pol; wire [2:0] pad_gpio_dm; wire pad_gpio_outenb; wire pad_gpio_out; wire pad_gpio_in; wire one_unbuf; wire zero_unbuf; wire one; wire zero; wire user_gpio_in; wire gpio_logic1; reg serial_data_out; /* Serial shift for the above (latched) values */ reg [PAD_CTRL_BITS-1:0] shift_register; /* Latch the output on the clock negative edge */ always @(negedge serial_clock or negedge resetn) begin if (resetn == 1'b0) begin /* Clear the shift register output */ serial_data_out <= 1'b0; end else begin serial_data_out <= shift_register[PAD_CTRL_BITS-1]; end end /* Propagate the clock and reset signals so that they aren't wired */ /* all over the chip, but are just wired between the blocks. */ assign serial_clock_out = serial_clock; assign resetn_out = resetn; assign serial_load_out = serial_load; always @(posedge serial_clock or negedge resetn) begin if (resetn == 1'b0) begin /* Clear shift register */ shift_register <= 'd0; end else begin /* Shift data in */ shift_register <= {shift_register[PAD_CTRL_BITS-2:0], serial_data_in}; end end always @(posedge serial_load or negedge resetn) begin if (resetn == 1'b0) begin /* Initial state on reset depends on applied defaults */ mgmt_ena <= gpio_defaults[MGMT_EN]; gpio_holdover <= gpio_defaults[HLDH]; gpio_slow_sel <= gpio_defaults[SLOW]; gpio_vtrip_sel <= gpio_defaults[TRIP]; gpio_ib_mode_sel <= gpio_defaults[MOD_SEL]; gpio_inenb <= gpio_defaults[INP_DIS]; gpio_outenb <= gpio_defaults[OEB]; gpio_dm <= gpio_defaults[DM+2:DM]; gpio_ana_en <= gpio_defaults[AN_EN]; gpio_ana_sel <= gpio_defaults[AN_SEL]; gpio_ana_pol <= gpio_defaults[AN_POL]; end else begin /* Load data */ mgmt_ena <= shift_register[MGMT_EN]; gpio_outenb <= shift_register[OEB]; gpio_holdover <= shift_register[HLDH]; gpio_inenb <= shift_register[INP_DIS]; gpio_ib_mode_sel <= shift_register[MOD_SEL]; gpio_ana_en <= shift_register[AN_EN]; gpio_ana_sel <= shift_register[AN_SEL]; gpio_ana_pol <= shift_register[AN_POL]; gpio_slow_sel <= shift_register[SLOW]; gpio_vtrip_sel <= shift_register[TRIP]; gpio_dm <= shift_register[DM+2:DM]; end end /* These pad configuration signals are static and do not change */ /* after setup. */ assign pad_gpio_holdover = gpio_holdover; assign pad_gpio_slow_sel = gpio_slow_sel; assign pad_gpio_vtrip_sel = gpio_vtrip_sel; assign pad_gpio_ib_mode_sel = gpio_ib_mode_sel; assign pad_gpio_ana_en = gpio_ana_en; assign pad_gpio_ana_sel = gpio_ana_sel; assign pad_gpio_ana_pol = gpio_ana_pol; assign pad_gpio_dm = gpio_dm; assign pad_gpio_inenb = gpio_inenb; /* Implement pad control behavior depending on state of mgmt_ena */ /* The pad value always goes back to the housekeeping module */ assign mgmt_gpio_in = pad_gpio_in; /* For 2-wire interfaces, the mgmt_gpio_oeb line is tied high at */ /* the control block. In this case, the output enable state is */ /* determined by the OEB configuration bit. */ assign pad_gpio_outenb = (mgmt_ena) ? ((mgmt_gpio_oeb == 1'b1) ? gpio_outenb : 1'b0) : user_gpio_oeb; /* For 2-wire interfaces, if the pad is configured for pull-up or */ /* pull-down, drive the output value locally to achieve the */ /* expected pull. */ assign pad_gpio_out = (mgmt_ena) ? ((mgmt_gpio_oeb == 1'b1) ? ((gpio_dm[2:1] == 2'b01) ? ~gpio_dm[0] : mgmt_gpio_out) : mgmt_gpio_out) : user_gpio_out; /* Buffer user_gpio_in with an enable that is set by the user domain vccd */ gpio_logic_high gpio_logic_high ( `ifdef USE_POWER_PINS .vccd1(vccd1), .vssd1(vssd1), `endif .gpio_logic1(gpio_logic1) ); /* If user project area is powered down, zero the pad input value */ /* going to the user project. */ assign user_gpio_in = pad_gpio_in & gpio_logic1; sky130_fd_sc_hd__conb_1 const_source ( `ifdef USE_POWER_PINS .VPWR(vccd), .VGND(vssd), .VPB(vccd), .VNB(vssd), `endif .HI(one_unbuf), .LO(zero_unbuf) ); assign zero = zero_unbuf; assign one = one_unbuf; endmodule `default_nettype wire