[PATCH] powerpc: Use the ibm,pa-features property if available (d205819e) · Commits · 戴 / test

arch/powerpc/kernel/prom.c

+70 −0

Original line number	Diff line number	Diff line
		@@ -885,6 +885,74 @@ void __init unflatten_device_tree(void)
		DBG(" <- unflatten_device_tree()\n");
		}

		/*
		* ibm,pa-features is a per-cpu property that contains a string of
		* attribute descriptors, each of which has a 2 byte header plus up
		* to 254 bytes worth of processor attribute bits. First header
		* byte specifies the number of bytes following the header.
		* Second header byte is an "attribute-specifier" type, of which
		* zero is the only currently-defined value.
		* Implementation: Pass in the byte and bit offset for the feature
		* that we are interested in. The function will return -1 if the
		* pa-features property is missing, or a 1/0 to indicate if the feature
		* is supported/not supported. Note that the bit numbers are
		* big-endian to match the definition in PAPR.
		*/
		static struct ibm_pa_feature {
		unsigned long cpu_features; /* CPU_FTR_xxx bit */
		unsigned int cpu_user_ftrs; /* PPC_FEATURE_xxx bit */
		unsigned char pabyte; /* byte number in ibm,pa-features */
		unsigned char pabit; /* bit number (big-endian) */
		unsigned char invert; /* if 1, pa bit set => clear feature */
		} ibm_pa_features[] __initdata = {
		{0, PPC_FEATURE_HAS_MMU, 0, 0, 0},
		{0, PPC_FEATURE_HAS_FPU, 0, 1, 0},
		{CPU_FTR_SLB, 0, 0, 2, 0},
		{CPU_FTR_CTRL, 0, 0, 3, 0},
		{CPU_FTR_NOEXECUTE, 0, 0, 6, 0},
		{CPU_FTR_NODSISRALIGN, 0, 1, 1, 1},
		{CPU_FTR_CI_LARGE_PAGE, 0, 1, 2, 0},
		};

		static void __init check_cpu_pa_features(unsigned long node)
		{
		unsigned char *pa_ftrs;
		unsigned long len, tablelen, i, bit;

		pa_ftrs = of_get_flat_dt_prop(node, "ibm,pa-features", &tablelen);
		if (pa_ftrs == NULL)
		return;

		/* find descriptor with type == 0 */
		for (;;) {
		if (tablelen < 3)
		return;
		len = 2 + pa_ftrs[0];
		if (tablelen < len)
		return; /* descriptor 0 not found */
		if (pa_ftrs[1] == 0)
		break;
		tablelen -= len;
		pa_ftrs += len;
		}

		/* loop over bits we know about */
		for (i = 0; i < ARRAY_SIZE(ibm_pa_features); ++i) {
		struct ibm_pa_feature *fp = &ibm_pa_features[i];

		if (fp->pabyte >= pa_ftrs[0])
		continue;
		bit = (pa_ftrs[2 + fp->pabyte] >> (7 - fp->pabit)) & 1;
		if (bit ^ fp->invert) {
		cur_cpu_spec->cpu_features \|= fp->cpu_features;
		cur_cpu_spec->cpu_user_features \|= fp->cpu_user_ftrs;
		} else {
		cur_cpu_spec->cpu_features &= ~fp->cpu_features;
		cur_cpu_spec->cpu_user_features &= ~fp->cpu_user_ftrs;
		}
		}
		}

		static int __init early_init_dt_scan_cpus(unsigned long node,
		const char *uname, int depth,
		void *data)
		@@ -969,6 +1037,8 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
		}
		#endif /* CONFIG_ALTIVEC */

		check_cpu_pa_features(node);

		#ifdef CONFIG_PPC_PSERIES
		if (nthreads > 1)
		cur_cpu_spec->cpu_features \|= CPU_FTR_SMT;

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