openwrt/target/linux/ramips/patches-4.14/101-mt7621-timer.patch

--- a/arch/mips/ralink/mt7621.c
+++ b/arch/mips/ralink/mt7621.c
@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/jiffies.h>
 
 #include <asm/mipsregs.h>
 #include <asm/smp-ops.h>
@@ -16,6 +17,7 @@
 #include <asm/mach-ralink/ralink_regs.h>
 #include <asm/mach-ralink/mt7621.h>
 #include <asm/mips-boards/launch.h>
+#include <asm/delay.h>
 
 #include <pinmux.h>
 
@@ -177,6 +179,58 @@ bool plat_cpu_core_present(int core)
 	return true;
 }
 
+#define LPS_PREC 8
+/*
+*  Re-calibration lpj(loop-per-jiffy).
+*  (derived from kernel/calibrate.c)
+*/
+static int udelay_recal(void)
+{
+	unsigned int i, lpj = 0;
+	unsigned long ticks, loopbit;
+	int lps_precision = LPS_PREC;
+
+	lpj = (1<<12);
+
+	while ((lpj <<= 1) != 0) {
+		/* wait for "start of" clock tick */
+		ticks = jiffies;
+		while (ticks == jiffies)
+			/* nothing */;
+
+		/* Go .. */
+		ticks = jiffies;
+		__delay(lpj);
+		ticks = jiffies - ticks;
+		if (ticks)
+			break;
+	}
+
+	/*
+	 * Do a binary approximation to get lpj set to
+	 * equal one clock (up to lps_precision bits)
+	 */
+	lpj >>= 1;
+	loopbit = lpj;
+	while (lps_precision-- && (loopbit >>= 1)) {
+		lpj |= loopbit;
+		ticks = jiffies;
+		while (ticks == jiffies)
+			/* nothing */;
+		ticks = jiffies;
+		__delay(lpj);
+		if (jiffies != ticks)   /* longer than 1 tick */
+			lpj &= ~loopbit;
+	}
+	printk(KERN_INFO "%d CPUs re-calibrate udelay(lpj = %d)\n", NR_CPUS, lpj);
+
+	for(i=0; i< NR_CPUS; i++)
+		cpu_data[i].udelay_val = lpj;
+
+	return 0;
+}
+device_initcall(udelay_recal);
+
 void prom_soc_init(struct ralink_soc_info *soc_info)
 {
 	void __iomem *sysc = (void __iomem *) KSEG1ADDR(MT7621_SYSC_BASE);
--- a/arch/mips/ralink/Kconfig
+++ b/arch/mips/ralink/Kconfig
@@ -59,6 +59,7 @@ choice
 		select CLKSRC_MIPS_GIC
 		select HW_HAS_PCI
 		select WEAK_REORDERING_BEYOND_LLSC
+		select GENERIC_CLOCKEVENTS_BROADCAST
 endchoice
 
 choice