ARM64 / ACPI: Parse MADT for SMP initialization

MADT contains the information for MPIDR which is essential for
SMP initialization, parse the GIC cpu interface structures to
get the MPIDR value and map it to cpu_logical_map(), and add
enabled cpu with valid MPIDR into cpu_possible_map.

ACPI 5.1 only has two explicit methods to boot up SMP, PSCI and
Parking protocol, but the Parking protocol is only specified for
ARMv7 now, so make PSCI as the only way for the SMP boot protocol
before some updates for the ACPI spec or the Parking protocol spec.

Parking protocol patches for SMP boot will be sent to upstream when
the new version of Parking protocol is ready.

CC: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Mark Rutland <mark.rutland@arm.com>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: Yijing Wang <wangyijing@huawei.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
Tested-by: Timur Tabi <timur@codeaurora.org>
Tested-by: Robert Richter <rrichter@cavium.com>
Acked-by: Robert Richter <rrichter@cavium.com>
Acked-by: Olof Johansson <olof@lixom.net>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/acpi.h

@@ -71,10 +71,12 @@ static inline bool acpi_has_cpu_in_madt(void)
 }
 
 static inline void arch_fix_phys_package_id(int num, u32 slot) { }
+void __init acpi_init_cpus(void);
 
 #else
 static inline bool acpi_psci_present(void) { return false; }
 static inline bool acpi_psci_use_hvc(void) { return false; }
+static inline void acpi_init_cpus(void) { }
 #endif /* CONFIG_ACPI */
 
 #endif /*_ASM_ACPI_H*/

arch/arm64/include/asm/cpu_ops.h

@@ -66,5 +66,6 @@ struct cpu_operations {
 extern const struct cpu_operations *cpu_ops[NR_CPUS];
 int __init cpu_read_ops(struct device_node *dn, int cpu);
 void __init cpu_read_bootcpu_ops(void);
+const struct cpu_operations *cpu_get_ops(const char *name);
 
 #endif /* ifndef __ASM_CPU_OPS_H */

arch/arm64/include/asm/smp.h

@@ -39,9 +39,10 @@ extern void show_ipi_list(struct seq_file *p, int prec);
 extern void handle_IPI(int ipinr, struct pt_regs *regs);
 
 /*
- * Setup the set of possible CPUs (via set_cpu_possible)
+ * Discover the set of possible CPUs and determine their
+ * SMP operations.
  */
-extern void smp_init_cpus(void);
+extern void of_smp_init_cpus(void);
 
 /*
  * Provide a function to raise an IPI cross call on CPUs in callmap.

arch/arm64/kernel/acpi.c

@@ -25,6 +25,10 @@
 #include <linux/of_fdt.h>
 #include <linux/smp.h>
 
+#include <asm/cputype.h>
+#include <asm/cpu_ops.h>
+#include <asm/smp_plat.h>
+
 int acpi_noirq = 1;		/* skip ACPI IRQ initialization */
 int acpi_disabled = 1;
 EXPORT_SYMBOL(acpi_disabled);
@@ -32,6 +36,12 @@ EXPORT_SYMBOL(acpi_disabled);
 int acpi_pci_disabled = 1;	/* skip ACPI PCI scan and IRQ initialization */
 EXPORT_SYMBOL(acpi_pci_disabled);
 
+/* Processors with enabled flag and sane MPIDR */
+static int enabled_cpus;
+
+/* Boot CPU is valid or not in MADT */
+static bool bootcpu_valid  __initdata;
+
 static bool param_acpi_off __initdata;
 static bool param_acpi_force __initdata;
 
@@ -85,6 +95,129 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
 	early_memunmap(map, size);
 }
 
+/**
+ * acpi_map_gic_cpu_interface - generates a logical cpu number
+ * and map to MPIDR represented by GICC structure
+ * @mpidr: CPU's hardware id to register, MPIDR represented in MADT
+ * @enabled: this cpu is enabled or not
+ *
+ * Returns the logical cpu number which maps to MPIDR
+ */
+static int __init acpi_map_gic_cpu_interface(u64 mpidr, u8 enabled)
+{
+	int i;
+
+	if (mpidr == INVALID_HWID) {
+		pr_info("Skip MADT cpu entry with invalid MPIDR\n");
+		return -EINVAL;
+	}
+
+	total_cpus++;
+	if (!enabled)
+		return -EINVAL;
+
+	if (enabled_cpus >=  NR_CPUS) {
+		pr_warn("NR_CPUS limit of %d reached, Processor %d/0x%llx ignored.\n",
+			NR_CPUS, total_cpus, mpidr);
+		return -EINVAL;
+	}
+
+	/* Check if GICC structure of boot CPU is available in the MADT */
+	if (cpu_logical_map(0) == mpidr) {
+		if (bootcpu_valid) {
+			pr_err("Firmware bug, duplicate CPU MPIDR: 0x%llx in MADT\n",
+			       mpidr);
+			return -EINVAL;
+		}
+
+		bootcpu_valid = true;
+	}
+
+	/*
+	 * Duplicate MPIDRs are a recipe for disaster. Scan
+	 * all initialized entries and check for
+	 * duplicates. If any is found just ignore the CPU.
+	 */
+	for (i = 1; i < enabled_cpus; i++) {
+		if (cpu_logical_map(i) == mpidr) {
+			pr_err("Firmware bug, duplicate CPU MPIDR: 0x%llx in MADT\n",
+			       mpidr);
+			return -EINVAL;
+		}
+	}
+
+	if (!acpi_psci_present())
+		return -EOPNOTSUPP;
+
+	cpu_ops[enabled_cpus] = cpu_get_ops("psci");
+	/* CPU 0 was already initialized */
+	if (enabled_cpus) {
+		if (!cpu_ops[enabled_cpus])
+			return -EINVAL;
+
+		if (cpu_ops[enabled_cpus]->cpu_init(NULL, enabled_cpus))
+			return -EOPNOTSUPP;
+
+		/* map the logical cpu id to cpu MPIDR */
+		cpu_logical_map(enabled_cpus) = mpidr;
+	}
+
+	enabled_cpus++;
+	return enabled_cpus;
+}
+
+static int __init
+acpi_parse_gic_cpu_interface(struct acpi_subtable_header *header,
+				const unsigned long end)
+{
+	struct acpi_madt_generic_interrupt *processor;
+
+	processor = (struct acpi_madt_generic_interrupt *)header;
+
+	if (BAD_MADT_ENTRY(processor, end))
+		return -EINVAL;
+
+	acpi_table_print_madt_entry(header);
+
+	acpi_map_gic_cpu_interface(processor->arm_mpidr & MPIDR_HWID_BITMASK,
+		processor->flags & ACPI_MADT_ENABLED);
+
+	return 0;
+}
+
+/* Parse GIC cpu interface entries in MADT for SMP init */
+void __init acpi_init_cpus(void)
+{
+	int count, i;
+
+	/*
+	 * do a partial walk of MADT to determine how many CPUs
+	 * we have including disabled CPUs, and get information
+	 * we need for SMP init
+	 */
+	count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
+			acpi_parse_gic_cpu_interface, 0);
+
+	if (!count) {
+		pr_err("No GIC CPU interface entries present\n");
+		return;
+	} else if (count < 0) {
+		pr_err("Error parsing GIC CPU interface entry\n");
+		return;
+	}
+
+	if (!bootcpu_valid) {
+		pr_err("MADT missing boot CPU MPIDR, not enabling secondaries\n");
+		return;
+	}
+
+	for (i = 0; i < enabled_cpus; i++)
+		set_cpu_possible(i, true);
+
+	/* Make boot-up look pretty */
+	pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
+}
+
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
 	struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
@@ -96,8 +229,20 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
 	 * boot protocol configuration data, or we will disable ACPI.
 	 */
 	if (table->revision > 5 ||
-	    (table->revision == 5 && fadt->minor_revision >= 1))
-		return 0;
+	    (table->revision == 5 && fadt->minor_revision >= 1)) {
+		/*
+		 * ACPI 5.1 only has two explicit methods to boot up SMP,
+		 * PSCI and Parking protocol, but the Parking protocol is
+		 * only specified for ARMv7 now, so make PSCI as the only
+		 * way for the SMP boot protocol before some updates for
+		 * the Parking protocol spec.
+		 */
+		if (acpi_psci_present())
+			return 0;
+
+		pr_warn("No PSCI support, will not bring up secondary CPUs\n");
+		return -EOPNOTSUPP;
+	}
 
 	pr_warn("Unsupported FADT revision %d.%d, should be 5.1+, will disable ACPI\n",
 		table->revision, fadt->minor_revision);

arch/arm64/kernel/cpu_ops.c

@@ -35,7 +35,7 @@ static const struct cpu_operations *supported_cpu_ops[] __initconst = {
 	NULL,
 };
 
-static const struct cpu_operations * __init cpu_get_ops(const char *name)
+const struct cpu_operations * __init cpu_get_ops(const char *name)
 {
 	const struct cpu_operations **ops = supported_cpu_ops;
 

arch/arm64/kernel/setup.c

@@ -393,13 +393,16 @@ void __init setup_arch(char **cmdline_p)
 	if (acpi_disabled) {
 		unflatten_device_tree();
 		psci_dt_init();
+		cpu_read_bootcpu_ops();
+#ifdef CONFIG_SMP
+		of_smp_init_cpus();
+#endif
 	} else {
 		psci_acpi_init();
+		acpi_init_cpus();
 	}
 
-	cpu_read_bootcpu_ops();
 #ifdef CONFIG_SMP
-	smp_init_cpus();
 	smp_build_mpidr_hash();
 #endif
 

arch/arm64/kernel/smp.c

@@ -322,7 +322,7 @@ void __init smp_prepare_boot_cpu(void)
  * cpu logical map array containing MPIDR values related to logical
  * cpus. Assumes that cpu_logical_map(0) has already been initialized.
  */
-void __init smp_init_cpus(void)
+void __init of_smp_init_cpus(void)
 {
 	struct device_node *dn = NULL;
 	unsigned int i, cpu = 1;