From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenzo Pieralisi Subject: Re: [RFC PATCH 1/4] ARM: kernel: add device tree init map function Date: Wed, 17 Oct 2012 11:48:41 +0100 Message-ID: <20121017104841.GB13189@e102568-lin.cambridge.arm.com> References: <1350393709-23546-1-git-send-email-lorenzo.pieralisi@arm.com> <1350393709-23546-2-git-send-email-lorenzo.pieralisi@arm.com> <507DC6C3.6090403@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <507DC6C3.6090403@gmail.com> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Rob Herring Cc: Mark Rutland , Nicolas Pitre , Dave Martin , Kukjin Kim , Russell King , Pawel Moll , Stephen Warren , Tony Lindgren , Catalin Marinas , "devicetree-discuss@lists.ozlabs.org" , Will Deacon , Amit Kucheria , Grant Likely , Benjamin Herrenschmidt , David Brown , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org Hi Rob, thanks for having a look. On Tue, Oct 16, 2012 at 09:42:43PM +0100, Rob Herring wrote: > On 10/16/2012 08:21 AM, Lorenzo Pieralisi wrote: > > When booting through a device tree, the kernel cpu logical id map can be > > initialized using device tree data passed by FW or through an embedded blob. > > > > This patch adds a function that parses device tree "cpu" nodes and > > retrieves the corresponding CPUs hardware identifiers (MPIDR). > > It sets the possible cpus and the cpu logical map values according to > > the number of CPUs defined in the device tree and respective properties. > > > > The primary CPU is assigned cpu logical number 0 to keep the current > > convention valid. > > > > Current bindings documentation is included in the patch: > > > > Documentation/devicetree/bindings/arm/cpus.txt > > > > Signed-off-by: Lorenzo Pieralisi > > --- > > Documentation/devicetree/bindings/arm/cpus.txt | 42 +++++++++++++++++++++++ > > arch/arm/include/asm/prom.h | 2 ++ > > arch/arm/kernel/devtree.c | 47 ++++++++++++++++++++++++++ > > 3 files changed, 91 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/arm/cpus.txt > > > > diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt > > new file mode 100644 > > index 0000000..897f3b4 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/arm/cpus.txt > > @@ -0,0 +1,42 @@ > > +* ARM CPUs binding description > > + > > +The device tree allows to describe the layout of CPUs in a system through > > +the "cpus" node, which in turn contains a number of subnodes (ie "cpu") > > +defining properties for every cpu. > > + > > +Bindings for CPU nodes follow the ePAPR standard, available from: > > + > > +http://devicetree.org > > + > > +For the ARM architecture every CPU node must contain the following property: > > + > > +- reg : property defining the CPU MPIDR[23:0] register bits > > defining or matching the MPIDR? I would say matching, otherwise it reads as if the MPIDR were writable. > > + > > +Every cpu node is required to set its device_type to "cpu". > > This is a bit questionable as device_type is deprecated for FDT. > However, since the ePAPR defines using it > > You should add a compatible property for the cpu model. Ok, I will. > > + > > +Example: > > + > > + cpus { > > + #size-cells = <0>; > > + #address-cells = <1>; > > + > > + CPU0: cpu@0 { > > + device_type = "cpu"; > > + reg = <0x0>; > > + }; > > + > > + CPU1: cpu@1 { > > + device_type = "cpu"; > > + reg = <0x1>; > > + }; > > + > > + CPU2: cpu@100 { > > + device_type = "cpu"; > > + reg = <0x100>; > > + }; > > + > > + CPU3: cpu@101 { > > + device_type = "cpu"; > > + reg = <0x101>; > > + }; > > + }; > > diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h > > index aeae9c6..8dd51dc 100644 > > --- a/arch/arm/include/asm/prom.h > > +++ b/arch/arm/include/asm/prom.h > > @@ -15,6 +15,7 @@ > > > > extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys); > > extern void arm_dt_memblock_reserve(void); > > +extern void __init arm_dt_init_cpu_maps(void); > > > > #else /* CONFIG_OF */ > > > > @@ -24,6 +25,7 @@ static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys) > > } > > > > static inline void arm_dt_memblock_reserve(void) { } > > +static inline void arm_dt_init_cpu_maps(void) { } > > > > #endif /* CONFIG_OF */ > > #endif /* ASMARM_PROM_H */ > > diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c > > index bee7f9d..c86e414 100644 > > --- a/arch/arm/kernel/devtree.c > > +++ b/arch/arm/kernel/devtree.c > > @@ -19,8 +19,10 @@ > > #include > > #include > > > > +#include > > #include > > #include > > +#include > > #include > > #include > > > > @@ -61,6 +63,51 @@ void __init arm_dt_memblock_reserve(void) > > } > > } > > > > +/* > > + * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree > > + * and builds the cpu logical map array containing MPIDR values related to > > + * logical cpus > > + * > > + * Updates the cpu possible mask with the number of parsed cpu nodes > > + */ > > +void __init arm_dt_init_cpu_maps(void) > > +{ > > + struct device_node *dn = NULL; > > + int i, cpu = 1; > > + > > + while ((dn = of_find_node_by_type(dn, "cpu")) && cpu <= nr_cpu_ids) { > > I think all /cpu nodes would have the right type. You could use > for_each_child_of_node here. Starting from /cpus, looked-up by path, right ? > > + const u32 *hwid; > > + int len; > > + > > + pr_debug(" * %s...\n", dn->full_name); > > + > > + hwid = of_get_property(dn, "reg", &len); > > + > > Use of_property_read_u32. Ok. Thanks, Lorenzo