From 0bfce37fae6f2913329d2ab862c7e159e39fcf9d Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sat, 18 Feb 2017 13:32:40 +0800
Subject: [PATCH] satman: do not use Si5324 automatic clock switching

The Si5324 is easily confused by the broken clock generated during link
initialization with BruteforceClockAligner. This commit prevents this problem.
---
 artiq/firmware/libboard/si5324.rs | 27 ++++++++++++++++++---------
 artiq/firmware/satman/lib.rs      | 18 +++++++++++++++---
 2 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/artiq/firmware/libboard/si5324.rs b/artiq/firmware/libboard/si5324.rs
index 4dad303a6..d5d789a73 100644
--- a/artiq/firmware/libboard/si5324.rs
+++ b/artiq/firmware/libboard/si5324.rs
@@ -130,7 +130,7 @@ fn locked() -> Result<bool> {
     Ok((read(130)? & 0x01) == 0) // LOL_INT=0
 }
 
-pub fn setup_hitless_clock_switching(settings: &FrequencySettings) -> Result<()> {
+pub fn setup(settings: &FrequencySettings) -> Result<()> {
     let s = map_frequency_settings(settings)?;
 
     reset(true);
@@ -145,12 +145,12 @@ pub fn setup_hitless_clock_switching(settings: &FrequencySettings) -> Result<()>
         return Err("Si5324 does not have expected product number");
     }
 
-    write(0,   read(0)? | 0x40)?;                 // FREE_RUN=1
-    write(1,   (read(1)? & 0xf0) | 0b0100)?;      // CK_PRIOR2=1 CK_PRIOR1=0
-    write(2,   (read(2)? & 0x0f) | (4 << 4))?;    // BWSEL=4
-    write(3,   read(3)? | 0x10)?;                 // SQ_ICAL=1
-    write(4,   (read(4)? & 0x3f) | (0b10 << 6))?; // AUTOSEL_REG=b10
-    write(6,   (read(6)? & 0xc0) | 0b001111)?;    // SFOUT2_REG=b001 SFOUT1_REG=b111
+    write(0,   read(0)? | 0x40)?;                         // FREE_RUN=1
+    write(2,   (read(2)? & 0x0f) | (4 << 4))?;            // BWSEL=4
+    write(21,  read(21)? & 0xfe);                         // CKSEL_PIN=0
+    write(3,   (read(3)? & 0x3f) | (0b01 << 6) | 0x10)?;  // CKSEL_REG=b01 SQ_ICAL=1
+    write(4,   (read(4)? & 0x3f) | (0b00 << 6))?;         // AUTOSEL_REG=b00
+    write(6,   (read(6)? & 0xc0) | 0b001111)?;            // SFOUT2_REG=b001 SFOUT1_REG=b111
     write(25,  (s.n1_hs  << 5 ) as u8)?;
     write(31,  (s.nc1_ls >> 16) as u8)?;
     write(32,  (s.nc1_ls >> 8 ) as u8)?;
@@ -164,8 +164,8 @@ pub fn setup_hitless_clock_switching(settings: &FrequencySettings) -> Result<()>
     write(46,  (s.n32    >> 16) as u8)?;
     write(47,  (s.n32    >> 8)  as u8)?;
     write(48,  (s.n32)          as u8)?;
-    write(137, read(137)? | 0x01)?;               // FASTLOCK=1
-    write(136, read(136)? | 0x40)?;               // ICAL=1
+    write(137, read(137)? | 0x01)?;                       // FASTLOCK=1
+    write(136, read(136)? | 0x40)?;                       // ICAL=1
 
     let t = clock::get_ms();
     while !locked()? {
@@ -176,3 +176,12 @@ pub fn setup_hitless_clock_switching(settings: &FrequencySettings) -> Result<()>
 
     Ok(())
 }
+
+pub fn select_ext_input(external: bool) -> Result<()> {
+    if external {
+        write(3,   (read(3)? & 0x3f) | (0b00 << 6))?;  // CKSEL_REG=b00
+    } else {
+        write(3,   (read(3)? & 0x3f) | (0b01 << 6))?;  // CKSEL_REG=b01
+    }
+    Ok(())
+}
diff --git a/artiq/firmware/satman/lib.rs b/artiq/firmware/satman/lib.rs
index ddaa6f934..4a507d3a5 100644
--- a/artiq/firmware/satman/lib.rs
+++ b/artiq/firmware/satman/lib.rs
@@ -32,6 +32,12 @@ const SI5324_SETTINGS: board::si5324::FrequencySettings
     n32    : 7139
 };
 
+fn drtio_link_is_up() -> bool {
+    unsafe {
+        board::csr::drtio::link_status_read() == 1
+    }
+}
+
 fn startup() {
     board::clock::init();
     info!("ARTIQ satellite manager starting...");
@@ -41,10 +47,16 @@ fn startup() {
     #[cfg(has_ad9516)]
     board::ad9516::init().expect("cannot initialize ad9516");
     board::i2c::init();
-    board::si5324::setup_hitless_clock_switching(&SI5324_SETTINGS)
-                  .expect("cannot initialize si5324");
+    board::si5324::setup(&SI5324_SETTINGS).expect("cannot initialize si5324");
 
-    loop {}
+    loop {
+        while !drtio_link_is_up() {}
+        info!("link is up, switching to recovered clock");
+        board::si5324::select_ext_input(true).expect("failed to switch clocks");
+        while drtio_link_is_up() {}
+        info!("link is down, switching to local crystal clock");
+        board::si5324::select_ext_input(false).expect("failed to switch clocks");
+    }
 }
 
 #[no_mangle]