From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH RFC 2/3] ARM: kernel: add support for cpu cache information Date: Wed, 8 Jan 2014 20:57:54 +0000 Message-ID: <20140108205754.GN27432@n2100.arm.linux.org.uk> References: <1389209168-17189-1-git-send-email-sudeep.holla@arm.com> <1389209168-17189-3-git-send-email-sudeep.holla@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1389209168-17189-3-git-send-email-sudeep.holla-5wv7dgnIgG8@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sudeep Holla Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Rob Herring , Benjamin Herrenschmidt , Greg Kroah-Hartman , Ashok Raj List-Id: devicetree@vger.kernel.org On Wed, Jan 08, 2014 at 07:26:07PM +0000, Sudeep Holla wrote: > +#if __LINUX_ARM_ARCH__ < 7 /* pre ARMv7 */ > + > +#define MAX_CACHE_LEVEL 1 /* Only 1 level supported */ > +#define CTR_CTYPE_SHIFT 24 > +#define CTR_CTYPE_MASK (1 << CTR_CTYPE_SHIFT) > + > +static inline unsigned int get_ctr(void) > +{ > + unsigned int ctr; > + asm volatile ("mrc p15, 0, %0, c0, c0, 1" : "=r" (ctr)); > + return ctr; > +} > + > +static enum cache_type get_cache_type(int level) > +{ > + if (level > MAX_CACHE_LEVEL) > + return CACHE_TYPE_NOCACHE; > + return get_ctr() & CTR_CTYPE_MASK ? > + CACHE_TYPE_SEPARATE : CACHE_TYPE_UNIFIED; So, what do we do for CPUs that don't implement the CTR? Just return random rubbish based on decoding the CPU Identity register as if it were the cache type register? -- FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up. Estimation in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad. Estimate before purchase was "up to 13.2Mbit". -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html