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Message-ID: <3703987.W8AZjrDbn0@vostro.rjw.lan>
Date: Tue, 20 Aug 2013 14:27:28 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org,
Viresh Kumar <viresh.kumar@...aro.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Jonas Bonn <jonas@...thpole.se>,
Michal Simek <monstr@...str.eu>,
Grant Likely <grant.likely@...aro.org>,
Rob Herring <rob.herring@...xeda.com>,
Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
Subject: Re: [PATCH v4 03/19] powerpc: refactor of_get_cpu_node to support other architectures
On Tuesday, August 20, 2013 10:30:05 AM Sudeep KarkadaNagesha wrote:
> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....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.
>
> PowerPC has it's own implementation to get the cpu node for a given
> logical index.
>
> This patch refactors the current implementation of of_get_cpu_node.
> This in preparation to move the implementation to DT core library.
> It separates out the logical to physical mapping so that a default
> matching of the physical id to the logical cpu index can be added
> when moved to common code. Architecture specific code can override it.
>
> Cc: Rob Herring <rob.herring@...xeda.com>
> Cc: Grant Likely <grant.likely@...aro.org>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
This needs an ACK from Ben to go anywhere.
Thanks,
Rafael
> ---
> arch/powerpc/kernel/prom.c | 76 ++++++++++++++++++++++++++++------------------
> 1 file changed, 47 insertions(+), 29 deletions(-)
>
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index eb23ac9..f7b8c0b 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -865,45 +865,63 @@ static int __init prom_reconfig_setup(void)
> __initcall(prom_reconfig_setup);
> #endif
>
> +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)
> {
> - int hardid;
> - struct device_node *np;
> + struct device_node *cpun, *cpus;
>
> - hardid = get_hard_smp_processor_id(cpu);
> + cpus = of_find_node_by_path("/cpus");
> + if (!cpus) {
> + pr_warn("Missing cpus node, bailing out\n");
> + return NULL;
> + }
>
> - for_each_node_by_type(np, "cpu") {
> - const u32 *intserv;
> - unsigned int plen, t;
> + 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
> + /* 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.
> */
> - intserv = of_get_property(np, "ibm,ppc-interrupt-server#s",
> - &plen);
> - if (intserv == NULL) {
> - const u32 *reg = of_get_property(np, "reg", NULL);
> - if (reg == NULL)
> - continue;
> - if (*reg == hardid) {
> - if (thread)
> - *thread = 0;
> - return np;
> - }
> - } else {
> - plen /= sizeof(u32);
> - for (t = 0; t < plen; t++) {
> - if (hardid == intserv[t]) {
> - if (thread)
> - *thread = t;
> - return np;
> - }
> - }
> - }
> + 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;
> }
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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