[PATCH v2 06/18] ARM64 / ACPI: Parse MADT to map logical cpu to MPIDR and get cpu_possible/present_map

[Hanjun Guo]

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 and
cpu_present_map.

Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
---
 arch/arm64/include/asm/acpi.h |    2 +
 arch/arm64/kernel/acpi.c      |  129 ++++++++++++++++++++++++++++++++++++++++-
 arch/arm64/kernel/smp.c       |   10 +++-
 3 files changed, 138 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 6e04868..e877967 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -64,6 +64,8 @@ static inline void arch_fix_phys_package_id(int num, u32 slot) { }
 extern int (*acpi_suspend_lowlevel)(void);
 #define acpi_wakeup_address 0
 
+#define MAX_GIC_CPU_INTERFACE 65535
+
 #endif /* CONFIG_ACPI */
 
 #endif /*_ASM_ACPI_H*/
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 69a315d..9e07d99 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -22,6 +22,9 @@
 #include <linux/bootmem.h>
 #include <linux/smp.h>
 
+#include <asm/smp_plat.h>
+#include <asm/cputype.h>
+
 int acpi_noirq;			/* skip ACPI IRQ initialization */
 int acpi_disabled;
 EXPORT_SYMBOL(acpi_disabled);
@@ -29,6 +32,8 @@ EXPORT_SYMBOL(acpi_disabled);
 int acpi_pci_disabled;		/* skip ACPI PCI scan and IRQ initialization */
 EXPORT_SYMBOL(acpi_pci_disabled);
 
+static int enabled_cpus;	/* Processors (GICC) with enabled flag in MADT */
+
 /*
  * __acpi_map_table() will be called before page_init(), so early_ioremap()
  * or early_memremap() should be called here to for ACPI table mapping.
@@ -49,6 +54,122 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
 	early_memunmap(map, size);
 }
 
+/**
+ * acpi_register_gic_cpu_interface - register a gic cpu interface and
+ * generates a logical cpu number
+ * @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 the gic cpu interface
+ */
+static int acpi_register_gic_cpu_interface(u64 mpidr, u8 enabled)
+{
+	int cpu;
+
+	if (mpidr == INVALID_HWID) {
+		pr_info("Skip invalid cpu hardware ID\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;
+	}
+
+	/* If it is the first CPU, no need to check duplicate MPIDRs */
+	if (!enabled_cpus)
+		goto skip_mpidr_check;
+
+	/*
+	 * Duplicate MPIDRs are a recipe for disaster. Scan
+	 * all initialized entries and check for
+	 * duplicates. If any is found just ignore the CPU.
+	 */
+	for_each_present_cpu(cpu) {
+		if (cpu_logical_map(cpu) == mpidr) {
+			pr_err("Firmware bug, duplicate CPU MPIDR: 0x%llx in MADT\n",
+			       mpidr);
+			return -EINVAL;
+		}
+	}
+
+skip_mpidr_check:
+	enabled_cpus++;
+
+	/* allocate a logical cpu id for the new comer */
+	if (cpu_logical_map(0) == mpidr) {
+		/*
+		 * boot_cpu_init() already hold bit 0 in cpu_present_mask
+		 * for BSP, no need to allocate again.
+		 */
+		cpu = 0;
+	} else {
+		cpu = cpumask_next_zero(-1, cpu_present_mask);
+	}
+
+	/* map the logical cpu id to cpu MPIDR */
+	cpu_logical_map(cpu) = mpidr;
+
+	set_cpu_possible(cpu, true);
+	set_cpu_present(cpu, true);
+
+	return cpu;
+}
+
+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_register_gic_cpu_interface(processor->arm_mpidr,
+		processor->flags & ACPI_MADT_ENABLED);
+
+	return 0;
+}
+
+/*
+ * Parse GIC cpu interface related entries in MADT
+ * returns 0 on success, < 0 on error
+ */
+static int __init acpi_parse_madt_gic_cpu_interface_entries(void)
+{
+	int count;
+
+	/*
+	 * 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, MAX_GIC_CPU_INTERFACE);
+
+	if (!count) {
+		pr_err("No GIC CPU interface entries present\n");
+		return -ENODEV;
+	} else if (count < 0) {
+		pr_err("Error parsing GIC CPU interface entry\n");
+		return count;
+	}
+
+	/* Make boot-up look pretty */
+	pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
+
+	return 0;
+}
+
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
 	struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
@@ -99,8 +220,12 @@ int __init acpi_boot_init(void)
 		return -ENODEV;
 
 	err = acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt);
-	if (err)
-		pr_err("Can't find FADT\n");
+	if (err) {
+		pr_err("Can't find FADT or error happened during parsing FADT\n");
+		return err;
+	}
+
+	err = acpi_parse_madt_gic_cpu_interface_entries();
 
 	return err;
 }
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 40f38f4..8f1d37c 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -36,6 +36,7 @@
 #include <linux/completion.h>
 #include <linux/of.h>
 #include <linux/irq_work.h>
+#include <linux/acpi.h>
 
 #include <asm/atomic.h>
 #include <asm/cacheflush.h>
@@ -458,7 +459,14 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 		if (err)
 			continue;
 
-		set_cpu_present(cpu, true);
+		/*
+		 * In ACPI mode, cpu_present_map was initialised when
+		 * MADT table was parsed which before this function
+		 * is called.
+		 */
+		if (acpi_disabled)
+			set_cpu_present(cpu, true);
+
 		max_cpus--;
 	}
 }
-- 
1.7.9.5

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