From 5e9bd11c4722d96fd35f1a60f80209474e4ffe76 Mon Sep 17 00:00:00 2001
From: Huw <huwpercival@xmos.com>
Date: Tue, 31 Jan 2023 15:05:57 +0000
Subject: [PATCH] Add version of clock tool which allows arbitrary clock
 setting

---
 CHANGELOG.md                              |  4 +++
 resources/clk_dac_setup/Makefile          |  5 ++-
 resources/clk_dac_setup/setup_mclk_bclk.c | 37 +++++++++++++++++++++++
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 44477e7..83c53b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # VocalFusion Raspberry Pi Setup Change Log
 
+## 5.5.0
+
+  * Add tool for setting arbitrary I2S clock
+
 ## 5.4.0
 
   * Add support for XVF3800
diff --git a/resources/clk_dac_setup/Makefile b/resources/clk_dac_setup/Makefile
index 24c7ec0..5177585 100644
--- a/resources/clk_dac_setup/Makefile
+++ b/resources/clk_dac_setup/Makefile
@@ -1,4 +1,4 @@
-default: bclk mclk
+default: bclk mclk setup_arbitrary_i2s_rate
 
 bclk: setup_mclk_bclk.c
 	gcc -g -o setup_bclk setup_mclk_bclk.c
@@ -6,6 +6,9 @@ bclk: setup_mclk_bclk.c
 mclk: setup_mclk_bclk.c
 	gcc -g -DMCLK -o setup_mclk setup_mclk_bclk.c
 
+setup_arbitrary_i2s_rate: setup_mclk_bclk.c
+	gcc -g -DARBITRARY_LRCLK -o setup_arbitrary_i2s_rate setup_mclk_bclk.c
+
 clean:
 	rm -f setup_mclk
 	rm -f setup_bclk
diff --git a/resources/clk_dac_setup/setup_mclk_bclk.c b/resources/clk_dac_setup/setup_mclk_bclk.c
index 9297f7a..dbfffc4 100644
--- a/resources/clk_dac_setup/setup_mclk_bclk.c
+++ b/resources/clk_dac_setup/setup_mclk_bclk.c
@@ -99,6 +99,18 @@ void gpioSetMode(unsigned gpio, unsigned mode)
     gpioReg[reg] = (gpioReg[reg] & ~(7<<shift)) | (mode<<shift);
 }
 
+struct clk_reg_t {
+    int i;
+    int f;
+};
+
+struct clk_reg_t calc_register_values(double input_khz, double output_khz) {
+    int i = input_khz/output_khz;
+    return (struct clk_reg_t) {
+        .i = i,
+        .f = ((input_khz/output_khz) - i) * 4096
+    };
+}
 
 unsigned getGpioHardwareRevision(void)
 {
@@ -279,6 +291,31 @@ int main(int argc, char *argv[])
     printf("MCLK at %.3fkHz: using %s (I=%-4d F=%-4d MASH=%d)\n",
             (float)(source_clk_kHz / (clk_i + (float) clk_f/4096)),
             clocks[clk_source], clk_i, clk_f, clk_mash);
+#elif defined(ARBITRARY_LRCLK)
+    if(argc <= 1) {
+        return 1;
+    }
+
+    double desired = atof(argv[1]);
+    if(desired < 8000) {
+        printf("bad arg, expected valid clock rate in hz");
+        return 1;
+    }
+    printf("requested lrclk %f\n", desired);
+
+    int clk_index = 2;
+    int clk_source = 0;
+    int clk_mash = 1;
+    int clk_enable = 1;
+    double bclk_per_lrclk = 64;
+    struct clk_reg_t c = calc_register_values(source_clk_kHz, (desired*bclk_per_lrclk)/1000);
+    int clk_i = c.i;
+    int clk_f = c.f;
+
+    printf("BCLK at %.3fkHz: using %s (I=%-4d F=%-4d MASH=%d)\n",
+            (float)(source_clk_kHz / (clk_i + (float) clk_f/4096)),
+            clocks[clk_source], clk_i, clk_f, clk_mash);
+
 #else
     int i2s_16000 = 0;
     if (argc > 1){