Thread (16 messages) 16 messages, 3 authors, 2014-01-09

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

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?

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