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[chip_tb] Integrate usbdpi into chip tb
Initial integration of usbdpi model into chip dvsim/tb; usbdev_test is up and running Simple chip_sw_usbdev_dpi_vseq created but incomplete. Include workaround for mmio32 routines reading X from usbdev. Added pull up resistors in diff receiver; driven by usbdev_aon_wake module in pinmux. Signed-off-by: Adrian Lees <[email protected]>
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| CAPI=2: | ||
| # Copyright lowRISC contributors. | ||
| # Licensed under the Apache License, Version 2.0, see LICENSE for details. | ||
| # SPDX-License-Identifier: Apache-2.0 | ||
| name: "lowrisc:dv:usb20_usbdpi:0.1" | ||
| description: "USB20-USBDPI" | ||
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| filesets: | ||
| files_rtl: | ||
| files: | ||
| - usb20_usbdpi.sv: { file_type: systemVerilogSource } | ||
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| targets: | ||
| default: | ||
| filesets: | ||
| - files_rtl |
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| // Copyright lowRISC contributors. | ||
| // Licensed under the Apache License, Version 2.0, see LICENSE for details. | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
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| module usb20_usbdpi ( | ||
| input clk_i, | ||
| input rst_ni, | ||
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| // VBUS/SENSE is driven high to activate/power the device. | ||
| output usb_sense_o, | ||
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| // Bidirectional, differential bus. | ||
| inout usb_p, | ||
| inout usb_n | ||
| ); | ||
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| // Functioning sketch of integration of USBDPI model into dv top-level tb | ||
| // as a connectivity and function test for ASIC | ||
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| // This module integrates the existing `usbdpi` module into the DV chip test | ||
| // bench, reconstructing the two unidirectional buses and driver enables that | ||
| // the DPI model requires for its operation, using just the bare bidirectional | ||
| // USB signals. | ||
| // | ||
| // Nomenclature notes: | ||
| // dp (or p) and dn (or n) are the two signals of the differential USB | ||
| // d2p means device to DPI | ||
| // p2d means DPI to device | ||
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| // VBUS/SENSE output from DPI | ||
| wire usb_sense_p2d; | ||
| // DPI driver enables | ||
| wire usb_dp_en_p2d; | ||
| wire usb_dn_en_p2d; | ||
| // DPI driver outputs | ||
| wire usb_dp_p2d; | ||
| wire usb_dn_p2d; | ||
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| assign usb_sense_o = usb_sense_p2d; | ||
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| // Weak pull downs so that we can detect the presence of the device, and we | ||
| // also prevent Z triggering 'X assertions' in usbdev | ||
| assign (weak0, weak1) usb_p = 1'b0; | ||
| assign (weak0, weak1) usb_n = 1'b0; | ||
| // Tri-stated output drivers | ||
| assign (strong0, strong1) usb_p = usb_dp_en_p2d ? usb_dp_p2d : 1'bZ; | ||
| assign (strong0, strong1) usb_n = usb_dn_en_p2d ? usb_dn_p2d : 1'bZ; | ||
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| /////////////////////////////////////////////////////////////////////////// | ||
| // Simple detection of pull up assertion indicating device presence; | ||
| // we simply respond to the first line to be pulled high by the device after | ||
| // VSENSE assertion, without regard for proper USB 2.0 timing | ||
| /////////////////////////////////////////////////////////////////////////// | ||
| logic usb_pullupdp_d2p; | ||
| logic usb_pullupdn_d2p; | ||
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| // Has either pull up been asserted by the device? | ||
| wire usb_pullup_detect = usb_pullupdp_d2p | usb_pullupdn_d2p; | ||
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| always_ff @(posedge clk_i or negedge rst_ni) begin | ||
| if (!rst_ni) begin | ||
| usb_pullupdp_d2p <= 1'b0; | ||
| usb_pullupdn_d2p <= 1'b0; | ||
| end else if (usb_sense_p2d && !usb_pullup_detect) begin | ||
| // Is the FS device pulling DP high? | ||
| if (usb_p === 1'b1) begin | ||
| usb_pullupdp_d2p <= 1'b1; | ||
| end | ||
| // Is the FS device pulling DN high, implying that it has been configured | ||
| // to perform pin-flipping? | ||
| if (usb_n === 1'b1) begin | ||
| usb_pullupdn_d2p <= 1'b1; | ||
| end | ||
| end | ||
| end | ||
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| /////////////////////////////////////////////////////////////////////////// | ||
| // Basic activity detection; DPI model indicates whether it is driving, | ||
| // but for the device we must detect a departure from the bus Idle state | ||
| /////////////////////////////////////////////////////////////////////////// | ||
| logic usb_dp_en_d2p_last; | ||
| logic usb_dn_en_d2p_last; | ||
| logic usb_dp_en_d2p; | ||
| logic usb_dn_en_d2p; | ||
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| always_comb begin | ||
| usb_dp_en_d2p = usb_dp_en_d2p_last; | ||
| usb_dn_en_d2p = usb_dn_en_d2p_last; | ||
| // Detect transmission start of DPI or device | ||
| if (usb_dp_en_p2d || (!usb_dp_en_d2p && usb_p != 1'b1)) begin | ||
| usb_dp_en_d2p = !usb_dp_en_p2d; | ||
| end | ||
| if (usb_dn_en_p2d || (!usb_dn_en_d2p && usb_n != 1'b0)) begin | ||
| usb_dn_en_d2p = !usb_dn_en_p2d; | ||
| end | ||
| end | ||
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| // Count of SE0 cycles (1/4 bit intervals). This is just an approximate | ||
| // detection of EOP for the purpose of ascertaining when the device is | ||
| // relinquishing the bus; it will also count during bus resets. | ||
| logic [2:0] se0_cnt; | ||
| always @(posedge clk_i or negedge rst_ni) begin | ||
| if (!rst_ni) begin | ||
| se0_cnt <= 'b0; | ||
| end else if (usb_p === 1'b0 && usb_n === 1'b0) begin | ||
| se0_cnt <= se0_cnt + 1'b1; | ||
| end else begin | ||
| se0_cnt <= 'b0; | ||
| end | ||
| end | ||
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| // Assume that the device is driving if the DPI model is not | ||
| always_ff @(posedge clk_i or negedge rst_ni) begin | ||
| if (!rst_ni) begin | ||
| usb_dp_en_d2p_last <= 1'b0; | ||
| usb_dn_en_d2p_last <= 1'b0; | ||
| end else if (usb_sense_p2d & usb_pullup_detect) begin | ||
| // Detect the end of EOP when the device has been transmitting | ||
| if (&{usb_dp_en_d2p_last, se0_cnt}) begin | ||
| usb_dp_en_d2p_last <= 1'b0; | ||
| end else begin | ||
| usb_dp_en_d2p_last <= usb_dp_en_d2p; | ||
| end | ||
| // Detect the end of EOP when the device has been transmitting | ||
| if ({usb_dn_en_d2p_last, se0_cnt}) begin | ||
| usb_dn_en_d2p_last <= 1'b0; | ||
| end else begin | ||
| usb_dn_en_d2p_last <= usb_dn_en_d2p; | ||
| end | ||
| end | ||
| end | ||
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| // USB DPI | ||
| usbdpi u_usbdpi ( | ||
| .clk_i (clk_i), | ||
| .rst_ni (rst_ni), | ||
| .clk_48MHz_i (clk_i), | ||
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| .sense_p2d (usb_sense_p2d), | ||
| .pullupdp_d2p (usb_pullupdp_d2p), | ||
| .pullupdn_d2p (usb_pullupdn_d2p), | ||
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| .dp_en_p2d (usb_dp_en_p2d), | ||
| .dp_p2d (usb_dp_p2d), | ||
| .dp_d2p (usb_p), | ||
| .dp_en_d2p (usb_dp_en_d2p), | ||
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| .dn_en_p2d (usb_dn_en_p2d), | ||
| .dn_p2d (usb_dn_p2d), | ||
| .dn_d2p (usb_n), | ||
| .dn_en_d2p (usb_dn_en_d2p), | ||
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| // ASIC communicates via true differential signaling | ||
| .d_p2d (), | ||
| .d_d2p (1'b0), // not used | ||
| .d_en_d2p (1'b0), | ||
| .se0_d2p (1'b0), // not used | ||
| .rx_enable_d2p (1'b0), | ||
| .tx_use_d_se0_d2p(1'b0) | ||
| ); | ||
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| endmodule |
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