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//-------------------------------------
// SPI controller for Caravel (PicoSoC)
//-------------------------------------
// Written by Tim Edwards
// efabless, inc. September 27, 2020
//-------------------------------------
//-----------------------------------------------------------
// This is a standalone slave SPI for the caravel chip that is
// intended to be independent of the picosoc and independent
// of all IP blocks except the power-on-reset. This SPI has
// register outputs controlling the functions that critically
// affect operation of the picosoc and so cannot be accessed
// from the picosoc itself. This includes the PLL enables
// and trim, and the crystal oscillator enable. It also has
// a general reset for the picosoc, an IRQ input, a bypass for
// the entire crystal oscillator and PLL chain, the
// manufacturer and product IDs and product revision number.
// To be independent of the 1.8V regulator, the slave SPI is
// synthesized with the 3V digital library and runs off of
// the 3V supply.
//
// This module is designed to be decoupled from the chip
// padframe and redirected to the wishbone bus under
// register control from the management SoC, such that the
// contents can be accessed from the management core via the
// SPI master.
//
//-----------------------------------------------------------
//------------------------------------------------------------
// Caravel defined registers:
// Register 0: SPI status and control (unused & reserved)
// Register 1 and 2: Manufacturer ID (0x0456) (readonly)
// Register 3: Product ID (= 16) (readonly)
// Register 4-7: Mask revision (readonly) --- Externally programmed
// with via programming. Via programmed with a script to match
// each customer ID.
//
// Register 8: PLL enables (2 bits)
// Register 9: PLL bypass (1 bit)
// Register 10: IRQ (1 bit)
// Register 11: reset (1 bit)
// Register 12: trap (1 bit) (readonly)
// Register 13-16: PLL trim (26 bits)
// Register 17: PLL output divider (3 bits)
// Register 18: PLL feedback divider (5 bits)
//------------------------------------------------------------
module housekeeping_spi(
`ifdef LVS
vdd, vss,
`endif
RSTB, SCK, SDI, CSB, SDO, sdo_enb,
pll_ena, pll_dco_ena, pll_div, pll_sel,
pll90_sel, pll_trim, pll_bypass, irq, reset,
trap, mask_rev_in, pass_thru_reset,
pass_thru_mgmt_sck, pass_thru_mgmt_csb,
pass_thru_mgmt_sdi, pass_thru_mgmt_sdo,
pass_thru_user_sck, pass_thru_user_csb,
pass_thru_user_sdi, pass_thru_user_sdo
);
`ifdef LVS
inout vdd; // 3.3V supply
inout vss; // common ground
`endif
input RSTB; // from padframe
input SCK; // from padframe
input SDI; // from padframe
input CSB; // from padframe
output SDO; // to padframe
output sdo_enb; // to padframe
output pll_ena;
output pll_dco_ena;
output [4:0] pll_div;
output [2:0] pll_sel;
output [2:0] pll90_sel;
output [25:0] pll_trim;
output pll_bypass;
output irq;
output reset;
input trap;
input [31:0] mask_rev_in; // metal programmed; 3.3V domain
// Pass-through programming mode for management area SPI flash
output pass_thru_reset;
output pass_thru_mgmt_sck;
output pass_thru_mgmt_csb;
output pass_thru_mgmt_sdi;
input pass_thru_mgmt_sdo;
// Pass-through programming mode for user area SPI flash
output pass_thru_user_sck;
output pass_thru_user_csb;
output pass_thru_user_sdi;
input pass_thru_user_sdo;
reg [25:0] pll_trim;
reg [4:0] pll_div;
reg [2:0] pll_sel;
reg [2:0] pll90_sel;
reg pll_dco_ena;
reg pll_ena;
reg pll_bypass;
reg reset_reg;
reg irq;
wire [7:0] odata;
wire [7:0] idata;
wire [7:0] iaddr;
wire trap;
wire rdstb;
wire wrstb;
wire pass_thru_mgmt; // Mode detected by spi_slave
wire pass_thru_mgmt_delay;
wire pass_thru_user; // Mode detected by spi_slave
wire pass_thru_user_delay;
wire loc_sdo;
// Pass-through mode handling. Signals may only be applied when the
// core processor is in reset.
assign pass_thru_mgmt_csb = reset ? ~pass_thru_mgmt_delay : 1'bz;
assign pass_thru_mgmt_sck = reset ? (pass_thru_mgmt ? SCK : 1'b0) : 1'bz;
assign pass_thru_mgmt_sdi = reset ? (pass_thru_mgmt ? SDI : 1'b0) : 1'bz;
assign pass_thru_user_csb = reset ? ~pass_thru_user_delay : 1'bz;
assign pass_thru_user_sck = reset ? (pass_thru_user ? SCK : 1'b0) : 1'bz;
assign pass_thru_user_sdi = reset ? (pass_thru_user ? SDI : 1'b0) : 1'bz;
assign SDO = pass_thru_mgmt ? pass_thru_mgmt_sdo :
pass_thru_user ? pass_thru_user_sdo : loc_sdo;
assign reset = pass_thru_reset ? 1'b1 : reset_reg;
// Instantiate the SPI slave module
housekeeping_spi_slave U1 (
.reset(~RSTB),
.SCK(SCK),
.SDI(SDI),
.CSB(CSB),
.SDO(loc_sdo),
.sdoenb(sdo_enb),
.idata(odata),
.odata(idata),
.oaddr(iaddr),
.rdstb(rdstb),
.wrstb(wrstb),
.pass_thru_mgmt(pass_thru_mgmt),
.pass_thru_mgmt_delay(pass_thru_mgmt_delay),
.pass_thru_user(pass_thru_user),
.pass_thru_user_delay(pass_thru_user_delay),
.pass_thru_reset(pass_thru_reset)
);
wire [11:0] mfgr_id;
wire [7:0] prod_id;
wire [31:0] mask_rev;
assign mfgr_id = 12'h456; // Hard-coded
assign prod_id = 8'h10; // Hard-coded
assign mask_rev = mask_rev_in; // Copy in to out.
// Send register contents to odata on SPI read command
// All values are 1-4 bits and no shadow registers are required.
assign odata =
(iaddr == 8'h00) ? 8'h00 : // SPI status (fixed)
(iaddr == 8'h01) ? {4'h0, mfgr_id[11:8]} : // Manufacturer ID (fixed)
(iaddr == 8'h02) ? mfgr_id[7:0] : // Manufacturer ID (fixed)
(iaddr == 8'h03) ? prod_id : // Product ID (fixed)
(iaddr == 8'h04) ? mask_rev[31:24] : // Mask rev (metal programmed)
(iaddr == 8'h05) ? mask_rev[23:16] : // Mask rev (metal programmed)
(iaddr == 8'h06) ? mask_rev[15:8] : // Mask rev (metal programmed)
(iaddr == 8'h07) ? mask_rev[7:0] : // Mask rev (metal programmed)
(iaddr == 8'h08) ? {6'b000000, pll_dco_ena, pll_ena} :
(iaddr == 8'h09) ? {7'b0000000, pll_bypass} :
(iaddr == 8'h0a) ? {7'b0000000, irq} :
(iaddr == 8'h0b) ? {7'b0000000, reset} :
(iaddr == 8'h0c) ? {7'b0000000, trap} :
(iaddr == 8'h0d) ? pll_trim[7:0] :
(iaddr == 8'h0e) ? pll_trim[15:8] :
(iaddr == 8'h0f) ? pll_trim[23:16] :
(iaddr == 8'h10) ? {6'b000000, pll_trim[25:24]} :
(iaddr == 8'h11) ? {2'b00, pll90_sel, pll_sel} :
(iaddr == 8'h12) ? {3'b000, pll_div} :
8'h00; // Default
// Register mapping and I/O to slave module
always @(posedge SCK or negedge RSTB) begin
if (RSTB == 1'b0) begin
// Set trim for PLL at (almost) slowest rate (~90MHz). However,
// pll_trim[12] must be set to zero for proper startup.
pll_trim <= 26'b11111111111110111111111111;
pll_sel <= 3'b010; // Default output divider divide-by-2
pll90_sel <= 3'b010; // Default secondary output divider divide-by-2
pll_div <= 5'b00100; // Default feedback divider divide-by-8
pll_dco_ena <= 1'b1; // Default free-running PLL
pll_ena <= 1'b0; // Default PLL turned off
pll_bypass <= 1'b1; // Default bypass mode (don't use PLL)
irq <= 1'b0;
reset_reg <= 1'b0;
end else if (wrstb == 1'b1) begin
case (iaddr)
8'h08: begin
pll_ena <= idata[0];
pll_dco_ena <= idata[1];
end
8'h09: begin
pll_bypass <= idata[0];
end
8'h0a: begin
irq <= idata[0];
end
8'h0b: begin
reset_reg <= idata[0];
end
// Register 0xc is read-only
8'h0d: begin
pll_trim[7:0] <= idata;
end
8'h0e: begin
pll_trim[15:8] <= idata;
end
8'h0f: begin
pll_trim[23:16] <= idata;
end
8'h10: begin
pll_trim[25:24] <= idata[1:0];
end
8'h11: begin
pll_sel <= idata[2:0];
pll90_sel <= idata[5:3];
end
8'h12: begin
pll_div <= idata[4:0];
end
endcase // (iaddr)
end
end
endmodule // housekeeping_spi
//------------------------------------------------------
// housekeeping_spi_slave.v
//------------------------------------------------------
// General purpose SPI slave module for the Caravel chip
//------------------------------------------------------
// Written by Tim Edwards
// efabless, inc., September 28, 2020
//------------------------------------------------
// This file is distributed free and open source
//------------------------------------------------
// SCK --- Clock input
// SDI --- Data input
// SDO --- Data output
// CSB --- Chip select (sense negative)
// idata --- Data from chip to transmit out, in 8 bits
// odata --- Input data to chip, in 8 bits
// addr --- Decoded address to upstream circuits
// rdstb --- Read strobe, tells upstream circuit to supply next byte to idata
// wrstb --- Write strobe, tells upstream circuit to latch odata.
// Data format (general purpose):
// 8 bit format
// 1st byte: Command word (see below)
// 2nd byte: Address word (register 0 to 255)
// 3rd byte: Data word (value 0 to 255)
// Command format:
// 00000000 No operation
// 10000000 Write until CSB raised
// 01000000 Read until CSB raised
// 11000000 Simultaneous read/write until CSB raised
// 11000100 Pass-through read/write to management area flash SPI until CSB raised
// 11000010 Pass-through read/write to user area flash SPI until CSB raised
// wrnnn000 Read/write as above, for nnn = 1 to 7 bytes, then terminate
// Lower three bits are reserved for future use.
// All serial bytes are read and written msb first.
// Fixed control and status registers
// Address 0 is reserved and contains flags for SPI mode. This is
// currently undefined and is always value 0.
// Address 1 is reserved and contains manufacturer ID low 8 bits.
// Address 2 is reserved and contains manufacturer ID high 4 bits.
// Address 3 is reserved and contains product ID (8 bits).
// Addresses 4 to 7 are reserved and contain the mask ID (32 bits).
// Addresses 8 to 255 are available for general purpose use.
`define COMMAND 3'b000
`define ADDRESS 3'b001
`define DATA 3'b010
`define USERPASS 3'b100
`define MGMTPASS 3'b101
module housekeeping_spi_slave(reset, SCK, SDI, CSB, SDO,
sdoenb, idata, odata, oaddr, rdstb, wrstb,
pass_thru_mgmt, pass_thru_mgmt_delay,
pass_thru_user, pass_thru_user_delay, pass_thru_reset);
input reset;
input SCK;
input SDI;
input CSB;
output SDO;
output sdoenb;
input [7:0] idata;
output [7:0] odata;
output [7:0] oaddr;
output rdstb;
output wrstb;
output pass_thru_mgmt;
output pass_thru_mgmt_delay;
output pass_thru_user;
output pass_thru_user_delay;
output pass_thru_reset;
reg [7:0] addr;
reg wrstb;
reg rdstb;
reg sdoenb;
reg [2:0] state;
reg [2:0] count;
reg writemode;
reg readmode;
reg [2:0] fixed;
wire [7:0] odata;
reg [6:0] predata;
wire [7:0] oaddr;
reg [7:0] ldata;
reg pass_thru_mgmt;
reg pass_thru_mgmt_delay;
reg pre_pass_thru_mgmt;
reg pass_thru_user;
reg pass_thru_user_delay;
reg pre_pass_thru_user;
wire csb_reset;
assign odata = {predata, SDI};
assign oaddr = (state == `ADDRESS) ? {addr[6:0], SDI} : addr;
assign SDO = ldata[7];
assign csb_reset = CSB | reset;
assign pass_thru_reset = pass_thru_mgmt_delay | pre_pass_thru_mgmt;
// Readback data is captured on the falling edge of SCK so that
// it is guaranteed valid at the next rising edge.
always @(negedge SCK or posedge csb_reset) begin
if (csb_reset == 1'b1) begin
wrstb <= 1'b0;
ldata <= 8'b00000000;
sdoenb <= 1'b1;
end else begin
// After CSB low, 1st SCK starts command
if (state == `DATA) begin
if (readmode == 1'b1) begin
sdoenb <= 1'b0;
if (count == 3'b000) begin
ldata <= idata;
end else begin
ldata <= {ldata[6:0], 1'b0}; // Shift out
end
end else begin
sdoenb <= 1'b1;
end
// Apply write strobe on SCK negative edge on the next-to-last
// data bit so that it updates data on the rising edge of SCK
// on the last data bit.
if (count == 3'b111) begin
if (writemode == 1'b1) begin
wrstb <= 1'b1;
end
end else begin
wrstb <= 1'b0;
end
end else if (state == `MGMTPASS || state == `USERPASS) begin
wrstb <= 1'b0;
sdoenb <= 1'b0;
end else begin
wrstb <= 1'b0;
sdoenb <= 1'b1;
end // ! state `DATA
end // ! csb_reset
end // always @ ~SCK
always @(posedge SCK or posedge csb_reset) begin
if (csb_reset == 1'b1) begin
// Default state on reset
addr <= 8'h00;
rdstb <= 1'b0;
predata <= 7'b0000000;
state <= `COMMAND;
count <= 3'b000;
readmode <= 1'b0;
writemode <= 1'b0;
fixed <= 3'b000;
pass_thru_mgmt <= 1'b0;
pass_thru_mgmt_delay <= 1'b0;
pre_pass_thru_mgmt <= 1'b0;
pass_thru_user = 1'b0;
pass_thru_user_delay <= 1'b0;
pre_pass_thru_user <= 1'b0;
end else begin
// After csb_reset low, 1st SCK starts command
if (state == `COMMAND) begin
rdstb <= 1'b0;
count <= count + 1;
if (count == 3'b000) begin
writemode <= SDI;
end else if (count == 3'b001) begin
readmode <= SDI;
end else if (count < 3'b101) begin
fixed <= {fixed[1:0], SDI};
end else if (count == 3'b101) begin
pre_pass_thru_mgmt <= SDI;
end else if (count == 3'b110) begin
pre_pass_thru_user <= SDI;
pass_thru_mgmt_delay <= pre_pass_thru_mgmt;
end else if (count == 3'b111) begin
pass_thru_user_delay <= pre_pass_thru_user;
if (pre_pass_thru_mgmt == 1'b1) begin
state <= `MGMTPASS;
pre_pass_thru_mgmt <= 1'b0;
end else if (pre_pass_thru_user == 1'b1) begin
state <= `USERPASS;
pre_pass_thru_user <= 1'b0;
end else begin
state <= `ADDRESS;
end
end
end else if (state == `ADDRESS) begin
count <= count + 1;
addr <= {addr[6:0], SDI};
if (count == 3'b111) begin
if (readmode == 1'b1) begin
rdstb <= 1'b1;
end
state <= `DATA;
end else begin
rdstb <= 1'b0;
end
end else if (state == `DATA) begin
predata <= {predata[6:0], SDI};
count <= count + 1;
if (count == 3'b111) begin
if (fixed == 3'b001) begin
state <= `COMMAND;
end else if (fixed != 3'b000) begin
fixed <= fixed - 1;
addr <= addr + 1; // Auto increment address (fixed)
end else begin
addr <= addr + 1; // Auto increment address (streaming)
end
end else begin
rdstb <= 1'b0;
end
end else if (state == `MGMTPASS) begin
pass_thru_mgmt <= 1'b1;
end else if (state == `USERPASS) begin
pass_thru_user <= 1'b1;
end // ! state `DATA | `MGMTPASS | `USERPASS
end // ! csb_reset
end // always @ SCK
endmodule // housekeeping_spi_slave