| Message ID | 1374069984-20567-2-git-send-email-Sudeep.KarkadaNagesha@arm.com (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
On Wed, 17 Jul 2013, Sudeep.KarkadaNagesha@arm.com wrote: > From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> > > Currently different drivers requiring to access cpu device node are > parsing the device tree themselves. Since the ordering in the DT need > not match the logical cpu ordering, the parsing logic needs to consider > that. However, this has resulted in lots of code duplication and in some > cases even incorrect logic. > > It's better to consolidate them by adding support for getting cpu > device node for a given logical cpu index in DT core library. However > logical to physical index mapping can be architecture specific. > > This patch adds of_get_cpu_node to retrieve a cpu device node for a > given logical cpu index. The default matching of the physical id to the > logical cpu index can be overridden by architecture specific code. > > 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@calxeda.com> > Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> > --- > drivers/of/base.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/of.h | 5 +++++ > 2 files changed, 71 insertions(+) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 5c54279..363b8f9 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -230,6 +230,72 @@ 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 architecure specific. Typo. > + * However this __weak function provides a default match of physical > + * id to logical cpu index. > + * > + * Returns 1 if the physical identifier and the logical index correspond > + * to the same cpu, 0 otherwise. > + */ > +int __weak arch_match_cpu_phys_id(int cpu, u64 phys_id) Please use a bool return type, and use true/false rather than 1/0 in the comment. > +{ > + return (u32)phys_id == cpu; > +} > + > +/** > + * of_get_cpu_node - Get device node associated with the given logical CPU > + * > + * @cpu: CPU number(logical index) for which device node is required > + * > + * The main purpose of this function is to retrieve the device node for the > + * given logical CPU index. It should be used to intialise the of_node in Typo. > + * 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 architecure specific and is built Typo. > + * 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) > +{ > + struct device_node *cpun, *cpus; > + const u32 *cell; > + u64 hwid; > + int ac, prop_len; > + > + cpus = of_find_node_by_path("/cpus"); > + if (WARN(!cpus, "Missing cpus node, bailing out\n")) > + return NULL; > + > + if (WARN_ON(of_property_read_u32(cpus, "#address-cells", &ac))) > + ac = of_n_addr_cells(cpus); > + > + for_each_child_of_node(cpus, cpun) { > + if (of_node_cmp(cpun->type, "cpu")) > + continue; > + cell = of_get_property(cpun, "reg", &prop_len); > + if (WARN(!cell, "%s: missing reg property\n", cpun->full_name)) > + continue; > + > + while (prop_len) { > + hwid = of_read_number(cell, ac); > + prop_len -= ac; > + if (arch_match_cpu_phys_id(cpu, hwid)) > + return cpun; > + } > + } > + > + return NULL; > +} > + > /** Checks if the given "compat" string matches one of the strings in > * the device's "compatible" property > */ > diff --git a/include/linux/of.h b/include/linux/of.h > index 1fd08ca..150b48e 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); > #define for_each_property_of_node(dn, pp) \ > for (pp = dn->properties; pp != NULL; pp = pp->next) > > @@ -458,6 +459,10 @@ 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) > +{ > + return NULL; > +} > > static inline int of_property_read_u64(const struct device_node *np, > const char *propname, u64 *out_value) > -- > 1.8.1.2 > > > _______________________________________________ > devicetree-discuss mailing list > devicetree-discuss@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/devicetree-discuss > -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/17/2013 09:06 AM, Sudeep.KarkadaNagesha@arm.com wrote: > From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> > > Currently different drivers requiring to access cpu device node are > parsing the device tree themselves. Since the ordering in the DT need > not match the logical cpu ordering, the parsing logic needs to consider > that. However, this has resulted in lots of code duplication and in some > cases even incorrect logic. > > It's better to consolidate them by adding support for getting cpu > device node for a given logical cpu index in DT core library. However > logical to physical index mapping can be architecture specific. > > This patch adds of_get_cpu_node to retrieve a cpu device node for a > given logical cpu index. The default matching of the physical id to the > logical cpu index can be overridden by architecture specific code. > > 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@calxeda.com> > Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> One comment below, but otherwise for patches 1-4, 8 and 9: Acked-by: Rob Herring <rob.herring@calxeda.com> Also, patch 3 needs to come before patch 2 or the matching will be wrong if patch 3 is not applied. > --- > drivers/of/base.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/of.h | 5 +++++ > 2 files changed, 71 insertions(+) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 5c54279..363b8f9 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -230,6 +230,72 @@ 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 architecure specific. > + * However this __weak function provides a default match of physical > + * id to logical cpu index. > + * > + * Returns 1 if the physical identifier and the logical index correspond > + * to the same cpu, 0 otherwise. > + */ > +int __weak arch_match_cpu_phys_id(int cpu, u64 phys_id) > +{ > + return (u32)phys_id == cpu; > +} > + > +/** > + * of_get_cpu_node - Get device node associated with the given logical CPU > + * > + * @cpu: CPU number(logical index) for which device node is required > + * > + * The main purpose of this function is to retrieve the device node for the > + * given logical CPU index. It should be used to intialise 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 architecure 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) > +{ > + struct device_node *cpun, *cpus; > + const u32 *cell; > + u64 hwid; > + int ac, prop_len; > + > + cpus = of_find_node_by_path("/cpus"); > + if (WARN(!cpus, "Missing cpus node, bailing out\n")) What happens on a system with no /cpus nodes? Seems like this is another case of adding new warnings to existing working systems. I'd replace all the WARN's with a single pr_warn on any errors below. For missing /cpus, I would just silently return. Rob > + return NULL; > + > + if (WARN_ON(of_property_read_u32(cpus, "#address-cells", &ac))) > + ac = of_n_addr_cells(cpus); > + > + for_each_child_of_node(cpus, cpun) { > + if (of_node_cmp(cpun->type, "cpu")) > + continue; > + cell = of_get_property(cpun, "reg", &prop_len); > + if (WARN(!cell, "%s: missing reg property\n", cpun->full_name)) > + continue; > + > + while (prop_len) { > + hwid = of_read_number(cell, ac); > + prop_len -= ac; > + if (arch_match_cpu_phys_id(cpu, hwid)) > + return cpun; > + } > + } > + > + return NULL; > +} -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 17/07/13 15:50, Rob Herring wrote: > On 07/17/2013 09:06 AM, Sudeep.KarkadaNagesha@arm.com wrote: >> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> >> >> Currently different drivers requiring to access cpu device node are >> parsing the device tree themselves. Since the ordering in the DT need >> not match the logical cpu ordering, the parsing logic needs to consider >> that. However, this has resulted in lots of code duplication and in some >> cases even incorrect logic. >> >> It's better to consolidate them by adding support for getting cpu >> device node for a given logical cpu index in DT core library. However >> logical to physical index mapping can be architecture specific. >> >> This patch adds of_get_cpu_node to retrieve a cpu device node for a >> given logical cpu index. The default matching of the physical id to the >> logical cpu index can be overridden by architecture specific code. >> >> 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@calxeda.com> >> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> > > One comment below, but otherwise for patches 1-4, 8 and 9: > > Acked-by: Rob Herring <rob.herring@calxeda.com> > > Also, patch 3 needs to come before patch 2 or the matching will be wrong > if patch 3 is not applied. Ah, correct will fix it in next version. > >> --- >> drivers/of/base.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> include/linux/of.h | 5 +++++ >> 2 files changed, 71 insertions(+) >> >> diff --git a/drivers/of/base.c b/drivers/of/base.c >> index 5c54279..363b8f9 100644 >> --- a/drivers/of/base.c >> +++ b/drivers/of/base.c >> @@ -230,6 +230,72 @@ 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 architecure specific. >> + * However this __weak function provides a default match of physical >> + * id to logical cpu index. >> + * >> + * Returns 1 if the physical identifier and the logical index correspond >> + * to the same cpu, 0 otherwise. >> + */ >> +int __weak arch_match_cpu_phys_id(int cpu, u64 phys_id) >> +{ >> + return (u32)phys_id == cpu; >> +} >> + >> +/** >> + * of_get_cpu_node - Get device node associated with the given logical CPU >> + * >> + * @cpu: CPU number(logical index) for which device node is required >> + * >> + * The main purpose of this function is to retrieve the device node for the >> + * given logical CPU index. It should be used to intialise 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 architecure 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) >> +{ >> + struct device_node *cpun, *cpus; >> + const u32 *cell; >> + u64 hwid; >> + int ac, prop_len; >> + >> + cpus = of_find_node_by_path("/cpus"); >> + if (WARN(!cpus, "Missing cpus node, bailing out\n")) > > What happens on a system with no /cpus nodes? Seems like this is another > case of adding new warnings to existing working systems. > > I'd replace all the WARN's with a single pr_warn on any errors below. > For missing /cpus, I would just silently return. Ah, forgot recent discussions on this, will fix it. Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/of/base.c b/drivers/of/base.c index 5c54279..363b8f9 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -230,6 +230,72 @@ 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 architecure specific. + * However this __weak function provides a default match of physical + * id to logical cpu index. + * + * Returns 1 if the physical identifier and the logical index correspond + * to the same cpu, 0 otherwise. + */ +int __weak arch_match_cpu_phys_id(int cpu, u64 phys_id) +{ + return (u32)phys_id == cpu; +} + +/** + * of_get_cpu_node - Get device node associated with the given logical CPU + * + * @cpu: CPU number(logical index) for which device node is required + * + * The main purpose of this function is to retrieve the device node for the + * given logical CPU index. It should be used to intialise 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 architecure 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) +{ + struct device_node *cpun, *cpus; + const u32 *cell; + u64 hwid; + int ac, prop_len; + + cpus = of_find_node_by_path("/cpus"); + if (WARN(!cpus, "Missing cpus node, bailing out\n")) + return NULL; + + if (WARN_ON(of_property_read_u32(cpus, "#address-cells", &ac))) + ac = of_n_addr_cells(cpus); + + for_each_child_of_node(cpus, cpun) { + if (of_node_cmp(cpun->type, "cpu")) + continue; + cell = of_get_property(cpun, "reg", &prop_len); + if (WARN(!cell, "%s: missing reg property\n", cpun->full_name)) + continue; + + while (prop_len) { + hwid = of_read_number(cell, ac); + prop_len -= ac; + if (arch_match_cpu_phys_id(cpu, hwid)) + return cpun; + } + } + + return NULL; +} + /** Checks if the given "compat" string matches one of the strings in * the device's "compatible" property */ diff --git a/include/linux/of.h b/include/linux/of.h index 1fd08ca..150b48e 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); #define for_each_property_of_node(dn, pp) \ for (pp = dn->properties; pp != NULL; pp = pp->next) @@ -458,6 +459,10 @@ 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) +{ + return NULL; +} static inline int of_property_read_u64(const struct device_node *np, const char *propname, u64 *out_value)