Commit 183912d3 authored by Sudeep KarkadaNagesha's avatar Sudeep KarkadaNagesha
Browse files

of: move of_get_cpu_node implementation to DT core library 



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: default avatarRob Herring <rob.herring@calxeda.com>
Signed-off-by: default avatarSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
parent 819d5965

arch/powerpc/include/asm/prom.h

+0 −3
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/prom.c

+0 −57
Original line number Diff line number Diff line
@@ -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;

drivers/of/base.c

+95 −0
Original line number Diff line number Diff line
@@ -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 +231,100 @@ 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 cpu index of a core/thread

 * @phys_id: physical identifier of a core/thread

 *

 * CPU logical to physical index mapping is architecture specific.

 * However this __weak function provides a default match of physical

 * id to logical cpu index. phys_id provided here is usually values read

 * from the device tree which must match the hardware internal registers.

 *

 * Returns true if the physical identifier and the logical cpu index

 * correspond to the same core/thread, 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;

		}

		cell += ac;

	}

	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;

		/* 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 (IS_ENABLED(CONFIG_PPC) &&

			__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);



/** Checks if the given "compat" string matches one of the strings in

 * the device's "compatible" property

 */

include/linux/cpu.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/of.h

+7 −0
Original line number Diff line number Diff line
@@ -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)

{

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