From 53142ae9f57306fb44870c8ea156892d15cb31a7 Mon Sep 17 00:00:00 2001
From: Solomon Peachy <pizza@shaftnet.org>
Date: Sat, 5 Sep 2020 20:16:17 -0400
Subject: jz4760:  Fix and re-enable the hardware udelay() timer

Change-Id: I591b4f023776b3501fce03e08bfc87a355f4c69b
---
 .../target/mips/ingenic_jz47xx/system-jz4760.c     | 31 +++++++++++++---------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/firmware/target/mips/ingenic_jz47xx/system-jz4760.c b/firmware/target/mips/ingenic_jz47xx/system-jz4760.c
index 19fe0ba661..10973f3e2b 100644
--- a/firmware/target/mips/ingenic_jz47xx/system-jz4760.c
+++ b/firmware/target/mips/ingenic_jz47xx/system-jz4760.c
@@ -28,7 +28,7 @@
 #include "kernel.h"
 #include "power.h"
 
-//#define USE_HW_UDELAY  // This is BROKEN.
+#define HW_UDELAY_TIMER 3
 #ifdef BOOTLOADER
 #define WITH_SERIAL
 #endif
@@ -341,28 +341,35 @@ void tlb_refill_handler(void)
     panicf("TLB refill handler at 0x%08lx! [0x%x]", read_c0_epc(), read_c0_badvaddr());
 }
 
-#ifdef USE_HW_UDELAY
+#ifdef HW_UDELAY_TIMER
 /* This enables the HW timer, set to EXT_XTAL / 4 (so @ 12/4 = 3MHz, 1 us = 3 ticks) */
 static void init_delaytimer(void)
 {
-    __tcu_disable_ost();
-    REG_OST_OSTCSR = OSTCSR_EXT_EN | OSTCSR_PRESCALE4 |  OSTCSR_CNT_MD;
-    REG_OST_OSTCNT = 0;
-    REG_OST_OSTDR = 0;
-    __tcu_enable_ost();
+    __tcu_stop_counter(HW_UDELAY_TIMER);
+    __tcu_disable_pwm_output(HW_UDELAY_TIMER);
+    __tcu_select_extalclk(HW_UDELAY_TIMER);
+    __tcu_clear_half_match_flag(HW_UDELAY_TIMER);
+    __tcu_clear_full_match_flag(HW_UDELAY_TIMER);
+    __tcu_mask_half_match_irq(HW_UDELAY_TIMER);
+    __tcu_mask_full_match_irq(HW_UDELAY_TIMER);
+    __tcu_select_clk_div4(HW_UDELAY_TIMER);
+    REG_TCU_TCNT(HW_UDELAY_TIMER) = 0;
+    REG_TCU_TDFR(HW_UDELAY_TIMER) = 0xffff;  /* wraps at 21.845ms */
+    __tcu_start_counter(HW_UDELAY_TIMER);
 }
 
-void udelay(unsigned int usec)
+void udelay(unsigned int usec) /* Must be under 21845 us! */
 {
-    if (!__tcu_ost_enabled())
+    if (!__tcu_counter_enabled(HW_UDELAY_TIMER))
 	init_delaytimer();
 
-    unsigned int now = REG_OST_OSTCNT;
+    unsigned short start = REG_TCU_TCNT(HW_UDELAY_TIMER);
 
     /* Figure out how many ticks we need */
     usec = (CFG_EXTAL / (4 * 1000 * 1000)) * (usec + 1);
 
-    while (REG_OST_OSTCNT - now < usec) {  }
+    while (((REG_TCU_TCNT(HW_UDELAY_TIMER) - start) & 0xffff) < usec) { }
+    // while (start + usec < REG_TCU_TCNT(HW_UDELAY_TIMER)) { };
 }
 #else
 void udelay(unsigned int usec)
@@ -681,7 +688,7 @@ void ICODE_ATTR system_main(void)
     for(i=0; i<IRQ_INTC_MAX; i++)
         dis_irq(i);
 
-#ifdef USE_HW_UDELAY
+#ifdef HW_UDELAY_TIMER
     init_delaytimer();
 #endif
 
-- 
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