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arm: mvebu: remove dependency of SMP init on static I/O mapping

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The ->smp_init_cpus() function is called very early during boot, at a
point where dynamic I/O mappings are not yet possible. However, in the
Armada 370/XP implementation of this function, we have to get the
number of CPUs. We used to do that by accessing a hardware register,
which requires relying on a static I/O mapping set up by
->map_io(). Not only this requires hardcoding a virtual address, but
it also prevents us from removing the static I/O mapping.

So this commit changes the way used to get the number of CPUs: we now
use the Device Tree, which is a representation of the hardware, and
provides us the number of available CPUs. This is also more accurate,
because it potentially allows to boot the Linux kernel on only a
number of CPUs given by the Device Tree, instead of unconditionally on
all CPUs.

As a consequence, the coherency_get_cpu_count() function becomes no
longer used, so we remove it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
This commit is contained in:
Thomas Petazzoni 2013-06-05 09:04:54 +02:00 committed by Jason Cooper
parent fdc0b43fbb
commit b21dcafea3
4 changed files with 11 additions and 17 deletions
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12
arch/arm/mach-mvebu/coherency.c
View File

@ -47,18 +47,6 @@ static struct of_device_id of_coherency_table[] = {
{ /* end of list */ },
};
#ifdef CONFIG_SMP
int coherency_get_cpu_count(void)
{
int reg, cnt;
reg = readl(coherency_base + COHERENCY_FABRIC_CFG_OFFSET);
cnt = (reg & 0xF) + 1;
return cnt;
}
#endif
/* Function defined in coherency_ll.S */
int ll_set_cpu_coherent(void __iomem *base_addr, unsigned int hw_cpu_id);

4
arch/arm/mach-mvebu/coherency.h
View File

@ -14,10 +14,6 @@
#ifndef __MACH_370_XP_COHERENCY_H
#define __MACH_370_XP_COHERENCY_H
#ifdef CONFIG_SMP
int coherency_get_cpu_count(void);
#endif
int set_cpu_coherent(int cpu_id, int smp_group_id);
int coherency_init(void);

2
arch/arm/mach-mvebu/common.h
View File

@ -15,6 +15,8 @@
#ifndef __ARCH_MVEBU_COMMON_H
#define __ARCH_MVEBU_COMMON_H
#define ARMADA_XP_MAX_CPUS 4
void mvebu_restart(char mode, const char *cmd);
void armada_370_xp_init_irq(void);

10
arch/arm/mach-mvebu/platsmp.c
View File

@ -88,8 +88,16 @@ static int __cpuinit armada_xp_boot_secondary(unsigned int cpu,
static void __init armada_xp_smp_init_cpus(void)
{
struct device_node *np;
unsigned int i, ncores;
ncores = coherency_get_cpu_count();
np = of_find_node_by_name(NULL, "cpus");
if (!np)
panic("No 'cpus' node found\n");
ncores = of_get_child_count(np);
if (ncores == 0 || ncores > ARMADA_XP_MAX_CPUS)
panic("Invalid number of CPUs in DT\n");
/* Limit possible CPUs to defconfig */
if (ncores > nr_cpu_ids) {