litex/targets/de0nano.py

from migen.fhdl.std import *
from migen.bus import wishbone

from misoclib.cpu.peripherals import gpio
from misoclib.mem import sdram
from misoclib.mem.sdram.phy import gensdrphy
from misoclib.com import uart
from misoclib.soc.sdram import SDRAMSoC

class _PLL(Module):
	def __init__(self, period_in, name, phase_shift, operation_mode):
		self.clk_in = Signal()
		self.clk_out = Signal()

		self.specials += Instance("ALTPLL",
			p_bandwidth_type = "AUTO",
			p_clk0_divide_by = 1,
			p_clk0_duty_cycle = 50,
			p_clk0_multiply_by = 2,
			p_clk0_phase_shift = "{}".format(str(phase_shift)),
			p_compensate_clock = "CLK0",
			p_inclk0_input_frequency = int(period_in*1000),
			p_intended_device_family = "Cyclone IV E",
			p_lpm_hint = "CBX_MODULE_PREFIX={}_pll".format(name),
			p_lpm_type = "altpll",
			p_operation_mode = operation_mode,
			i_inclk=self.clk_in,
			o_clk=self.clk_out,
			i_areset=0,
			i_clkena=0x3f,
			i_clkswitch=0,
			i_configupdate=0,
			i_extclkena=0xf,
			i_fbin=1,
			i_pfdena=1,
			i_phasecounterselect=0xf,
			i_phasestep=1,
			i_phaseupdown=1,
			i_pllena=1,
			i_scanaclr=0,
			i_scanclk=0,
			i_scanclkena=1,
			i_scandata=0,
			i_scanread=0,
			i_scanwrite=0
		)

class _CRG(Module):
	def __init__(self, platform):
		self.clock_domains.cd_sys = ClockDomain()
		self.clock_domains.cd_sys_ps = ClockDomain()
		self.clock_domains.cd_por = ClockDomain(reset_less=True)

		clk50 = platform.request("clk50")

		sys_pll = _PLL(20, "sys", 0, "NORMAL")
		self.submodules += sys_pll
		self.comb += [
			sys_pll.clk_in.eq(clk50),
			self.cd_sys.clk.eq(sys_pll.clk_out)
		]

		sdram_pll = _PLL(20, "sdram", -3000, "ZERO_DELAY_BUFFER")
		self.submodules += sdram_pll
		self.comb += [
			sdram_pll.clk_in.eq(clk50),
			self.cd_sys_ps.clk.eq(sdram_pll.clk_out)
		]

		# Power on Reset (vendor agnostic)
		rst_n = Signal()
		self.sync.por += rst_n.eq(1)
		self.comb += [
			self.cd_por.clk.eq(self.cd_sys.clk),
			self.cd_sys.rst.eq(~rst_n),
			self.cd_sys_ps.rst.eq(~rst_n)
		]

		self.comb += platform.request("sdram_clock").eq(self.cd_sys_ps.clk)

class BaseSoC(SDRAMSoC):
	default_platform = "de0nano"

	def __init__(self, platform, **kwargs):
		SDRAMSoC.__init__(self, platform,
			clk_freq=100*1000000,
			with_rom=True,
			**kwargs)

		self.submodules.crg = _CRG(platform)

		if not self.with_main_ram:
			sdram_geom_settings = sdram.GeomSettings(
				bank_a=2,
				row_a=13,
				col_a=9
			)

			sdram_timing_settings = sdram.TimingSettings(
				tRP=self.ns(20),
				tRCD=self.ns(20),
				tWR=self.ns(20),
				tWTR=2,
				tREFI=self.ns(7800, False),
				tRFC=self.ns(70)
			)
			sdram_controller_settings = sdram.ControllerSettings(
				req_queue_size=8,
				read_time=32,
				write_time=16
			)
			self.submodules.sdrphy = gensdrphy.GENSDRPHY(platform.request("sdram"))
			self.register_sdram_phy(self.sdrphy, sdram_geom_settings, sdram_timing_settings,
				sdram_controller_settings)

default_subtarget = BaseSoC