Re: [PATCH RFC 2/3] ARM: kernel: add support for cpu cache information
From: Russell King - ARM Linux <hidden>
Date: 2014-01-08 20:58:15
Also in:
linux-arm-kernel, linuxppc-dev, lkml
From: Russell King - ARM Linux <hidden>
Date: 2014-01-08 20:58:15
Also in:
linux-arm-kernel, linuxppc-dev, lkml
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