From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com>
Currently, the code in setup-common.c for powerpc assumes that all
clock rates are same in a smp system. This value is cached in the
variable named ppc_proc_freq and is the value that is reported in
/proc/cpuinfo.
However on the PowerNV platform, the clock rate is same only across
the threads of the same core. Hence the value that is reported in
/proc/cpuinfo is incorrect on PowerNV platforms. We need a better way
to query and report the correct value of the processor clock in
/proc/cpuinfo.
The patch achieves this by creating a machdep_call named
get_proc_freq() which is expected to returns the frequency in Hz. The
code in show_cpuinfo() can invoke this method to display the correct
clock rate on platforms that have implemented this method. On the
other powerpc platforms it can use the value cached in ppc_proc_freq.
Signed-off-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/machdep.h | 2 ++
arch/powerpc/kernel/setup-common.c | 16 ++++++++++++----
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/machdep.h
b/arch/powerpc/include/asm/machdep.h
index ad3025d..eb1c6d4 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -113,6 +113,8 @@ struct machdep_calls {
/* Optional, may be NULL. */
void (*show_cpuinfo)(struct seq_file *m);
void (*show_percpuinfo)(struct seq_file *m, int i);
+ /* Returns the current operating frequency of "cpu" in Hz */
+ unsigned long (*get_proc_freq)(unsigned int cpu);
void (*init_IRQ)(void);
diff --git a/arch/powerpc/kernel/setup-common.c
b/arch/powerpc/kernel/setup-common.c
index bc76cc6..bdd3045 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -209,6 +209,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
{
unsigned long cpu_id = (unsigned long)v - 1;
unsigned int pvr;
+ unsigned long proc_freq;
unsigned short maj;
unsigned short min;
@@ -260,12 +261,19 @@ static int show_cpuinfo(struct seq_file *m, void *v)
#endif /* CONFIG_TAU */
/*
- * Assume here that all clock rates are the same in a
- * smp system. -- Cort
+ * Platforms that have variable clock rates, should implement
+ * the method ppc_md.get_proc_freq() that reports the clock
+ * rate of a given cpu. The rest can use ppc_proc_freq to
+ * report the clock rate that is same across all cpus.
*/
- if (ppc_proc_freq)
+ if (ppc_md.get_proc_freq)
+ proc_freq = ppc_md.get_proc_freq(cpu_id);
+ else
+ proc_freq = ppc_proc_freq;
+
+ if (proc_freq)
seq_printf(m, "clock\t\t: %lu.%06luMHz\n",
- ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
+ proc_freq / 1000000, proc_freq % 1000000);
if (ppc_md.show_percpuinfo != NULL)
ppc_md.show_percpuinfo(m, cpu_id);
--
1.8.3.1
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