From: Pavel Tatashin <pasha.tatashin@oracle.com>
Date: Thu, 15 Jun 2017 14:40:59 +0000 (-0400)
Subject: sparc64: broken %tick frequency on spitfire cpus
X-Git-Tag: v4.13-rc1~93^2~5^2
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=eea9833453bd39e2f35325abb985d00486c8aa69;p=linux.git

sparc64: broken %tick frequency on spitfire cpus

After early boot time stamps project the %tick frequency is detected
incorrectly on spittfire cpus.

We must use cpuid of boot cpu to find corresponding cpu node in OpenBoot,
and extract clock-frequency property from there.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/arch/sparc/kernel/time_64.c b/arch/sparc/kernel/time_64.c
index a62758ce9e19..f584c53e769a 100644
--- a/arch/sparc/kernel/time_64.c
+++ b/arch/sparc/kernel/time_64.c
@@ -162,9 +162,34 @@ static unsigned long tick_add_tick(unsigned long adj)
 	return new_tick;
 }
 
+/* Searches for cpu clock frequency with given cpuid in OpenBoot tree */
+static unsigned long cpuid_to_freq(phandle node, int cpuid)
+{
+	bool is_cpu_node = false;
+	unsigned long freq = 0;
+	char type[128];
+
+	if (!node)
+		return freq;
+
+	if (prom_getproperty(node, "device_type", type, sizeof(type)) != -1)
+		is_cpu_node = (strcmp(type, "cpu") == 0);
+
+	/* try upa-portis then cpuid to get cpuid, see prom_64.c */
+	if (is_cpu_node && (prom_getint(node, "upa-portis") == cpuid ||
+			    prom_getint(node, "cpuid") == cpuid))
+		freq = prom_getintdefault(node, "clock-frequency", 0);
+	if (!freq)
+		freq = cpuid_to_freq(prom_getchild(node), cpuid);
+	if (!freq)
+		freq = cpuid_to_freq(prom_getsibling(node), cpuid);
+
+	return freq;
+}
+
 static unsigned long tick_get_frequency(void)
 {
-	return local_cpu_data().clock_tick;
+	return cpuid_to_freq(prom_root_node, hard_smp_processor_id());
 }
 
 static struct sparc64_tick_ops tick_operations __cacheline_aligned = {