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Subject[PATCH 07/19] ARM64 / ACPI: Parse MADT to map logical cpu to MPIDR and get cpu_possible/present_map
Date
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@linaro.org>
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
---
arch/arm64/include/asm/acpi.h | 2 +
arch/arm64/kernel/acpi.c | 127 +++++++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/smp.c | 10 +++-
3 files changed, 138 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 67dac90..5ce85f8 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -50,6 +50,8 @@ static inline bool acpi_has_cpu_in_madt(void)
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 374926f..801e268 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>
+
/*
* We never plan to use RSDT on arm/arm64 as its deprecated in spec but this
* variable is still required by the ACPI core
@@ -42,6 +45,9 @@ int acpi_psci_present;
/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
int acpi_psci_use_hvc;

+/* Processors (GICC) with enabled flag in MADT */
+static int enabled_cpus;
+
/*
* __acpi_map_table() will be called before page_init(), so early_ioremap()
* or early_memremap() should be called here to for ACPI table mapping.
@@ -62,6 +68,122 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
early_iounmap(map, size);
}

+/**
+ * acpi_register_gic_cpu_interface - register a gic cpu interface and
+ * generates a logic cpu number
+ * @mpidr: CPU's hardware id to register, MPIDR represented in MADT
+ * @enabled: this cpu is enabled or not
+ *
+ * Returns the logic 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 logic 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 allocte again.
+ */
+ cpu = 0;
+ } else {
+ cpu = cpumask_next_zero(-1, cpu_present_mask);
+ }
+
+ /* map the logic 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->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;
@@ -122,6 +244,11 @@ int __init acpi_boot_init(void)
if (err)
pr_err("Can't find FADT\n");

+ /* Get the boot CPU's MPIDR before MADT parsing */
+ cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
+
+ 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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