Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2299d03a authored by Gautham R. Shenoy's avatar Gautham R. Shenoy Committed by Benjamin Herrenschmidt
Browse files

powerpc: powernv: Framework to show the correct clock in /proc/cpuinfo 



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: default avatarGautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 2196c6f1

arch/powerpc/include/asm/machdep.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/setup-common.c

+12 −4
Original line number Diff line number Diff line
@@ -212,6 +212,7 @@ 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;
@@ -263,12 +264,19 @@ 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);