arch: m68k: Introduce trivial PIT based timer

The QEMU emulation of m68k does not support DMA timer, the only
timer that is supported is the PIT timer. Implement trivial PIT
timer support for m68k.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

2 files changed, 58 insertions, 2 deletions

diff --git a/arch/m68k/include/asm/immap.h b/arch/m68k/include/asm/immap.h
index 3b515fe2c65..aafa4f40cb3 100644
--- a/arch/m68k/include/asm/immap.h
+++ b/arch/m68k/include/asm/immap.h
@@ -25,6 +25,8 @@
 #define CFG_SYS_TMRINTR_PEND		(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(6)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 
 #define CFG_SYS_INTR_BASE		(MMAP_INTC0)
@@ -47,6 +49,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(0x1E)		/* Level must include inorder to work */
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 
 #define CFG_SYS_INTR_BASE		(MMAP_INTC0)
@@ -72,6 +76,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL7 | MCFSIM_ICR_PRI3)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 2000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 #endif				/* CONFIG_M5249 */
 
@@ -95,6 +101,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL3 | MCFSIM_ICR_PRI3)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 2000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 #endif				/* CONFIG_M5253 */
 
@@ -114,6 +122,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(0x1E) /* Interrupt level 3, priority 6 */
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 
 #define CFG_SYS_INTR_BASE		(MMAP_INTC0)
@@ -139,6 +149,8 @@
 #define CFG_SYS_TMRINTR_PEND	(0)
 #define CFG_SYS_TMRINTR_PRI		(INT_ICR1_TMR3PI | INT_ICR1_TMR3IPL(5))
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 #endif				/* CONFIG_M5272 */
 
@@ -161,6 +173,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(0x1E)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 #endif				/* CONFIG_M5275 */
 
@@ -183,6 +197,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(0x1E)		/* Level must include inorder to work */
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 #endif				/* CONFIG_M5282 */
 
@@ -207,6 +223,8 @@
 #define CFG_SYS_TMRINTR_PRI          (MCFSIM_ICR_AUTOVEC | \
 					MCFSIM_ICR_LEVEL7 | MCFSIM_ICR_PRI3)
 #define CFG_SYS_TIMER_PRESCALER      (((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 #endif                          /* CONFIG_M5307 */
 
@@ -226,6 +244,8 @@
 #define CFG_SYS_TMRINTR_PEND		(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(6)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 
 #define CFG_SYS_INTR_BASE		(MMAP_INTC0)
@@ -248,6 +268,8 @@
 #define CFG_SYS_TMRINTR_PEND	(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(6)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 
 #define CFG_SYS_INTR_BASE		(MMAP_INTC0)
@@ -278,6 +300,8 @@
 #define CFG_SYS_TMRINTR_PEND		(CFG_SYS_TMRINTR_MASK)
 #define CFG_SYS_TMRINTR_PRI		(6)
 #define CFG_SYS_TIMER_PRESCALER	(((gd->bus_clk / 1000000) - 1) << 8)
+#else
+#define CFG_SYS_UDELAY_BASE		(MMAP_PIT0)
 #endif
 
 #define CFG_SYS_INTR_BASE		(MMAP_INTC0)
diff --git a/arch/m68k/lib/time.c b/arch/m68k/lib/time.c
index 500e4dbbba2..61db1e6c500 100644
--- a/arch/m68k/lib/time.c
+++ b/arch/m68k/lib/time.c
@@ -111,8 +111,6 @@ ulong get_timer(ulong base)
 	return (timestamp - base);
 }
 
-#endif				/* CONFIG_MCFTMR */
-
 /*
  * This function is derived from PowerPC code (read timebase as long long).
  * On M68K it just returns the timer value.
@@ -121,6 +119,40 @@ unsigned long long get_ticks(void)
 {
 	return get_timer(0);
 }
+#else
+static u64 timer64 __section(".data");
+static u16 timer16 __section(".data");
+
+uint64_t __weak get_ticks(void)
+{
+	volatile pit_t *timerp = (pit_t *) (CFG_SYS_UDELAY_BASE);
+	u16 val = ~timerp->pcntr;
+
+	if (timer16 > val)
+		timer64 += 0xffff - timer16 + val;
+	else
+		timer64 += val - timer16;
+
+	timer16 = val;
+
+	return timer64;
+}
+
+/* PIT timer */
+int timer_init(void)
+{
+	volatile pit_t *timerp = (pit_t *) (CFG_SYS_UDELAY_BASE);
+
+	timer16 = 0;
+	timer64 = 0;
+
+	/* Set up PIT as timebase clock */
+	timerp->pmr = 0xffff;
+	timerp->pcsr = PIT_PCSR_EN | PIT_PCSR_OVW;
+
+	return 0;
+}
+#endif				/* CONFIG_MCFTMR */
 
 unsigned long usec2ticks(unsigned long usec)
 {