From cf13833e3c2b401ef999752f9e5afba134d632f8 Mon Sep 17 00:00:00 2001
From: Piense <piense@gmail.com>
Date: Mon, 24 Aug 2020 16:17:02 +0200
Subject: [PATCH] cores/clock: add initial NX-OSCA support.

---
 litex/soc/cores/clock.py | 81 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/litex/soc/cores/clock.py b/litex/soc/cores/clock.py
index 16cd8442f..327f47a7f 100644
--- a/litex/soc/cores/clock.py
+++ b/litex/soc/cores/clock.py
@@ -3,6 +3,7 @@
 #
 # Copyright (c) 2018-2020 Florent Kermarrec <florent@enjoy-digital.fr>
 # Copyright (c) 2019 Michael Betz <michibetz@gmail.com>
+# Copyright (c) 2020 Piense <piense@gmail.com>
 # SPDX-License-Identifier: BSD-2-Clause
 
 """Clock Abstraction Modules"""
@@ -756,6 +757,86 @@ class ECP5PLL(Module):
             self.params["o_CLKO{}".format(n_to_l[n])]        = clk
         self.specials += Instance("EHXPLLL", **self.params)
 
+# Lattice / NX -------------------------------------------------------------------------------------
+# NOTE This clock has +/- 15% accuracy
+class NXOSCA(Module):
+    nclkouts_max = 2
+    clk_hf_div_range = (0, 255)
+    clk_hf_freq_range = (1.76, 450e6)
+    clk_hf_freq = 450e6
+
+    def __init__(self):
+        self.logger = logging.getLogger("NXOSCA")
+        self.logger.info("Creating NXOSCA.")
+
+        self.hf_clk_out    = {}
+        self.hfsdc_clk_out = {}
+        self.lf_clk_out    = None
+        self.params        = {}
+
+    def create_hf_clk(self, cd, freq, margin=.05):
+        """450 - 1.7 Mhz Clk"""
+        (clko_freq_min, clko_freq_max) = self.clk_hf_freq_range
+        assert freq >= clko_freq_min
+        assert freq <= clko_freq_max
+        clkout = Signal()
+        self.hf_clk_out = (clkout, freq, margin)
+        self.comb += cd.clk.eq(clkout)
+        create_clkout_log(self.logger, cd.name, freq, margin, -1)
+
+    def create_hfsdc_clk(self, cd, freq, margin=.05):
+        """450 - 1.7 Mhz Clk. Can only be connected to the SEDC_CLK port of CONFIG_CLKRST_CORE"""
+        (clko_freq_min, clko_freq_max) = self.clk_hf_freq_range
+        assert freq >= clko_freq_min
+        assert freq <= clko_freq_max
+        clkout = Signal()
+        self.hfsdc_clk_out = (clkout, freq, margin)
+        self.comb += cd.clk.eq(clkout)
+        create_clkout_log(self.logger, cd.name, freq, margin, -1)
+
+    def create_lf_clk(self, cd):
+        """128 kHz Clock"""
+        clkout = Signal()
+        self.lf_clk_out = (clkout)
+        self.comb += cd.clk.eq(clkout)
+        create_clkout_log(self.logger, cd.name, 128e3, 19e3, -1)
+
+    def compute_divisor(self, freq, margin):
+        config = {}
+
+        for divisor in range(*self.clk_hf_div_range):
+            clk_freq = self.clk_hf_freq/(divisor+1)
+            if abs(clk_freq - freq) <= freq*margin:
+                config["freq"]  = clk_freq
+                config["div"]   = str(divisor)
+                break
+
+        if config:
+            compute_config_log(self.logger, config)
+            return config["div"]
+
+        raise ValueError("Bad OSC freq.")
+
+    def do_finalize(self):
+        if self.hf_clk_out:
+            divisor = self.compute_divisor(self.hf_clk_out[1], self.hf_clk_out[2])
+            self.params["i_HFOUTEN"]      = 0b1
+            self.params["p_HF_CLK_DIV"]   = divisor
+            self.params["o_HFCLKOUT"]     = self.hf_clk_out[0]
+            self.params["p_HF_OSC_EN"]    = "ENABLED"
+
+        if self.hfsdc_clk_out:
+            divisor = self.compute_divisor(self.hfsdc_clk_out[1], self.hfsdc_clk_out[2])
+            self.params["i_HFSDSCEN"]        = 0b1
+            self.params["p_HF_SED_SEC_DIV"]  = divisor
+            self.params["o_HFSDCOUT"]        = self.hfsdc_clk_out[0]
+
+        if self.lf_clk_out is not None:
+            self.params["o_LFCLKOUT"] = self.lf_clk_out[0]
+            self.params["p_LF_OUTPUT_EN"] = "ENABLED"
+
+        self.specials += Instance("OSCA", **self.params)
+
 # Intel / Generic ---------------------------------------------------------------------------------
 
 class IntelClocking(Module, AutoCSR):