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ARM: mvebu: synchronize secondary CPU clocks on resume

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The Armada XP has multiple cores clocked by independent clocks. The
SMP startup code contains a function called set_secondary_cpus_clock()
called in armada_xp_smp_prepare_cpus() to ensure the clocks of the
secondary CPUs match the clock of the boot CPU.

With the introduction of suspend/resume, this operation is no longer
needed when booting the system, but also when existing the suspend to
RAM state. Therefore this commit reworks a bit the logic: instead of
configuring the clock of all secondary CPUs in
armada_xp_smp_prepare_cpus(), we do it on a per-secondary CPU basis in
armada_xp_boot_secondary(), as this function gets called when existing
suspend to RAM for each secondary CPU.

Since the function now only takes care of one CPU, we rename it from
set_secondary_cpus_clock() to set_secondary_cpu_clock(), and it looses
its __init marker, as it is now used beyond the system initialization.

Note that we can't use smp_processor_id() directly, because when
exiting from suspend to RAM, the code is apparently executed with
preemption enabled, so smp_processor_id() is not happy (prints a
warning). We therefore switch to using get_cpu()/put_cpu(), even
though we pretty much have the guarantee that the code starting the
secondary CPUs is going to run on the boot CPU and will not be
migrated.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1416585613-2113-14-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
This commit is contained in:
Thomas Petazzoni 2014-11-21 17:00:10 +01:00 committed by Jason Cooper
parent 77ea46d133
commit b9b1de0f4d
1 changed files with 15 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
arch/arm/mach-mvebu/platsmp.c
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@ -33,7 +33,7 @@
#define AXP_BOOTROM_BASE 0xfff00000 #define AXP_BOOTROM_BASE 0xfff00000
#define AXP_BOOTROM_SIZE 0x100000 #define AXP_BOOTROM_SIZE 0x100000
static struct clk *__init get_cpu_clk(int cpu) static struct clk *get_cpu_clk(int cpu)
{ {
struct clk *cpu_clk; struct clk *cpu_clk;
struct device_node *np = of_get_cpu_node(cpu, NULL); struct device_node *np = of_get_cpu_node(cpu, NULL);
@ -46,29 +46,28 @@ static struct clk *__init get_cpu_clk(int cpu)
return cpu_clk; return cpu_clk;
} }
static void __init set_secondary_cpus_clock(void) static void set_secondary_cpu_clock(unsigned int cpu)
{ {
int thiscpu, cpu; int thiscpu;
unsigned long rate; unsigned long rate;
struct clk *cpu_clk; struct clk *cpu_clk;
thiscpu = smp_processor_id(); thiscpu = get_cpu();
cpu_clk = get_cpu_clk(thiscpu); cpu_clk = get_cpu_clk(thiscpu);
if (!cpu_clk) if (!cpu_clk)
return; goto out;
clk_prepare_enable(cpu_clk); clk_prepare_enable(cpu_clk);
rate = clk_get_rate(cpu_clk); rate = clk_get_rate(cpu_clk);
/* set all the other CPU clk to the same rate than the boot CPU */ cpu_clk = get_cpu_clk(cpu);
for_each_possible_cpu(cpu) { if (!cpu_clk)
if (cpu == thiscpu) goto out;
continue; clk_set_rate(cpu_clk, rate);
cpu_clk = get_cpu_clk(cpu); clk_prepare_enable(cpu_clk);
if (!cpu_clk)
return; out:
clk_set_rate(cpu_clk, rate); put_cpu();
clk_prepare_enable(cpu_clk);
}
} }
static int armada_xp_boot_secondary(unsigned int cpu, struct task_struct *idle) static int armada_xp_boot_secondary(unsigned int cpu, struct task_struct *idle)
@ -78,6 +77,7 @@ static int armada_xp_boot_secondary(unsigned int cpu, struct task_struct *idle)
pr_info("Booting CPU %d\n", cpu); pr_info("Booting CPU %d\n", cpu);
hw_cpu = cpu_logical_map(cpu); hw_cpu = cpu_logical_map(cpu);
set_secondary_cpu_clock(hw_cpu);
mvebu_pmsu_set_cpu_boot_addr(hw_cpu, armada_xp_secondary_startup); mvebu_pmsu_set_cpu_boot_addr(hw_cpu, armada_xp_secondary_startup);
/* /*
@ -126,7 +126,6 @@ static void __init armada_xp_smp_prepare_cpus(unsigned int max_cpus)
struct resource res; struct resource res;
int err; int err;
set_secondary_cpus_clock();
flush_cache_all(); flush_cache_all();
set_cpu_coherent(); set_cpu_coherent();