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of: move of_get_cpu_node implementation to DT core library

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This patch moves the generalized implementation of of_get_cpu_node from
PowerPC to DT core library, thereby adding support for retrieving cpu
node for a given logical cpu index on any architecture.

The CPU subsystem can now use this function to assign of_node in the
cpu device while registering CPUs.

It is recommended to use these helper function only in pre-SMP/early
initialisation stages to retrieve CPU device node pointers in logical
ordering. Once the cpu devices are registered, it can be retrieved easily
from cpu device of_node which avoids unnecessary parsing and matching.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
This commit is contained in:
Sudeep KarkadaNagesha
2013-08-15 14:01:40 +01:00
parent 819d596568
commit 183912d352
5 changed files with 103 additions and 60 deletions
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57
arch/powerpc/kernel/prom.c
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@@ -870,63 +870,6 @@ bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
return (int)phys_id == get_hard_smp_processor_id(cpu);
}
static bool __of_find_n_match_cpu_property(struct device_node *cpun,
const char *prop_name, int cpu, unsigned int *thread)
{
const __be32 *cell;
int ac, prop_len, tid;
u64 hwid;
ac = of_n_addr_cells(cpun);
cell = of_get_property(cpun, prop_name, &prop_len);
if (!cell)
return false;
prop_len /= sizeof(*cell);
for (tid = 0; tid < prop_len; tid++) {
hwid = of_read_number(cell, ac);
if (arch_match_cpu_phys_id(cpu, hwid)) {
if (thread)
*thread = tid;
return true;
}
cell += ac;
}
return false;
}
/* Find the device node for a given logical cpu number, also returns the cpu
* local thread number (index in ibm,interrupt-server#s) if relevant and
* asked for (non NULL)
*/
struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
{
struct device_node *cpun, *cpus;
cpus = of_find_node_by_path("/cpus");
if (!cpus) {
pr_warn("Missing cpus node, bailing out\n");
return NULL;
}
for_each_child_of_node(cpus, cpun) {
if (of_node_cmp(cpun->type, "cpu"))
continue;
/* Check for non-standard "ibm,ppc-interrupt-server#s" property
* for thread ids on PowerPC. If it doesn't exist fallback to
* standard "reg" property.
*/
if (__of_find_n_match_cpu_property(cpun,
"ibm,ppc-interrupt-server#s", cpu, thread))
return cpun;
if (__of_find_n_match_cpu_property(cpun, "reg", cpu, thread))
return cpun;
}
return NULL;
}
EXPORT_SYMBOL(of_get_cpu_node);
#if defined(CONFIG_DEBUG_FS) && defined(DEBUG)
static struct debugfs_blob_wrapper flat_dt_blob;