[RFC PATCH 4/4] of: move of_get_cpu_node implementation to DT core library
Sudeep KarkadaNagesha
Sudeep.KarkadaNagesha at arm.com
Fri Aug 16 03:09:40 EST 2013
From: Sudeep KarkadaNagesha <sudeep.karkadanagesha at arm.com>
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: Rob Herring <rob.herring at calxeda.com>
Cc: Grant Likely <grant.likely at linaro.org>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha at arm.com>
---
arch/powerpc/include/asm/prom.h | 3 --
arch/powerpc/kernel/prom.c | 55 ------------------------
drivers/of/base.c | 94 +++++++++++++++++++++++++++++++++++++++++
include/linux/cpu.h | 1 +
include/linux/of.h | 7 +++
5 files changed, 102 insertions(+), 58 deletions(-)
diff --git a/arch/powerpc/include/asm/prom.h b/arch/powerpc/include/asm/prom.h
index bc2da15..ac204e0 100644
--- a/arch/powerpc/include/asm/prom.h
+++ b/arch/powerpc/include/asm/prom.h
@@ -43,9 +43,6 @@ void of_parse_dma_window(struct device_node *dn, const void *dma_window_prop,
extern void kdump_move_device_tree(void);
-/* CPU OF node matching */
-struct device_node *of_get_cpu_node(int cpu, unsigned int *thread);
-
/* cache lookup */
struct device_node *of_find_next_cache_node(struct device_node *np);
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 594c9f9..1c14cd4 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -870,61 +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;
- }
- }
- 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 ibm,ppc-interrupt-server#s. If it doesn't exist
- * fallback to "reg" property and assume no threads
- */
- 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;
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 5c54279..d088e45 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -18,6 +18,7 @@
* 2 of the License, or (at your option) any later version.
*/
#include <linux/ctype.h>
+#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/spinlock.h>
@@ -230,6 +231,99 @@ const void *of_get_property(const struct device_node *np, const char *name,
}
EXPORT_SYMBOL(of_get_property);
+/*
+ * arch_match_cpu_phys_id - Match the given logical CPU and physical id
+ *
+ * @cpu: logical index of a cpu
+ * @phys_id: physical identifier of a cpu
+ *
+ * CPU logical to physical index mapping is architecture specific.
+ * However this __weak function provides a default match of physical
+ * id to logical cpu index.
+ *
+ * Returns true if the physical identifier and the logical index correspond
+ * to the same cpu, false otherwise.
+ */
+bool __weak arch_match_cpu_phys_id(int cpu, u64 phys_id)
+{
+ return (u32)phys_id == cpu;
+}
+
+/**
+ * Checks if the given "prop_name" property holds the physical id of the
+ * core/thread corresponding to the logical cpu 'cpu'. If 'thread' is not
+ * NULL, local thread number within the core is returned in it.
+ */
+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;
+ }
+ }
+ return false;
+}
+
+/**
+ * of_get_cpu_node - Get device node associated with the given logical CPU
+ *
+ * @cpu: CPU number(logical index) for which device node is required
+ * @thread: if not NULL, local thread number within the physical core is
+ * returned
+ *
+ * The main purpose of this function is to retrieve the device node for the
+ * given logical CPU index. It should be used to initialize the of_node in
+ * cpu device. Once of_node in cpu device is populated, all the further
+ * references can use that instead.
+ *
+ * CPU logical to physical index mapping is architecture specific and is built
+ * before booting secondary cores. This function uses arch_match_cpu_phys_id
+ * which can be overridden by architecture specific implementation.
+ *
+ * Returns a node pointer for the logical cpu if found, else 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;
+#ifdef CONFIG_PPC
+ /* Check for historical "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;
+#endif
+ if (__of_find_n_match_cpu_property(cpun, "reg", cpu, thread))
+ return cpun;
+ }
+ return NULL;
+}
+EXPORT_SYMBOL(of_get_cpu_node);
+
/** Checks if the given "compat" string matches one of the strings in
* the device's "compatible" property
*/
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index ab0eade..3dfed2b 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -28,6 +28,7 @@ struct cpu {
extern int register_cpu(struct cpu *cpu, int num);
extern struct device *get_cpu_device(unsigned cpu);
extern bool cpu_is_hotpluggable(unsigned cpu);
+extern bool arch_match_cpu_phys_id(int cpu, u64 phys_id);
extern int cpu_add_dev_attr(struct device_attribute *attr);
extern void cpu_remove_dev_attr(struct device_attribute *attr);
diff --git a/include/linux/of.h b/include/linux/of.h
index 1fd08ca..c0bb2f1 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -266,6 +266,7 @@ extern int of_device_is_available(const struct device_node *device);
extern const void *of_get_property(const struct device_node *node,
const char *name,
int *lenp);
+extern struct device_node *of_get_cpu_node(int cpu, unsigned int *thread);
#define for_each_property_of_node(dn, pp) \
for (pp = dn->properties; pp != NULL; pp = pp->next)
@@ -459,6 +460,12 @@ static inline const void *of_get_property(const struct device_node *node,
return NULL;
}
+static inline struct device_node *of_get_cpu_node(int cpu,
+ unsigned int *thread)
+{
+ return NULL;
+}
+
static inline int of_property_read_u64(const struct device_node *np,
const char *propname, u64 *out_value)
{
--
1.8.1.2
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