ARM64: kernel: make cpu_ops hooks DT agnostic

ARM64 CPU operations such as cpu_init and cpu_init_idle take
a struct device_node pointer as a parameter, which corresponds to
the device tree node of the logical cpu on which the operation
has to be applied.

With the advent of ACPI on arm64, where MADT static table entries
are used to initialize cpus, the device tree node parameter
in cpu_ops hooks become useless when booting with ACPI, since
in that case cpu device tree nodes are not present and can not be
used for cpu initialization.

The current cpu_init hook requires a struct device_node pointer
parameter because it is called while parsing the device tree to
initialize CPUs, when the cpu_logical_map (that is used to match
a cpu node reg property to a device tree node) for a given logical
cpu id is not set up yet. This means that the cpu_init hook cannot
rely on the of_get_cpu_node function to retrieve the device tree
node corresponding to the logical cpu id passed in as parameter,
so the cpu device tree node must be passed in as a parameter to fix
this catch-22 dependency cycle.

This patch reshuffles the cpu_logical_map initialization code so
that the cpu_init cpu_ops hook can safely use the of_get_cpu_node
function to retrieve the cpu device tree node, removing the need for
the device tree node pointer parameter.

In the process, the patch removes device tree node parameters
from all cpu_ops hooks, in preparation for SMP DT/ACPI cpus
initialization consolidation.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Hanjun Guo <hanjun.guo@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Tested-by: Mark Rutland <mark.rutland@arm.com> [DT]
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 28 insertions, 11 deletions

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 2cb008177252..98eb68b5660f 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -319,6 +319,23 @@ void __init smp_prepare_boot_cpu(void)
 }
 
 /*
+ * Initialize cpu operations for a logical cpu and
+ * set it in the possible mask on success
+ */
+static int __init smp_cpu_setup(int cpu)
+{
+	if (cpu_read_ops(cpu))
+		return -ENODEV;
+
+	if (cpu_ops[cpu]->cpu_init(cpu))
+		return -ENODEV;
+
+	set_cpu_possible(cpu, true);
+
+	return 0;
+}
+
+/*
  * Enumerate the possible CPU set from the device tree and build the
  * cpu logical map array containing MPIDR values related to logical
  * cpus. Assumes that cpu_logical_map(0) has already been initialized.
@@ -395,12 +412,6 @@ void __init of_smp_init_cpus(void)
 		if (cpu >= NR_CPUS)
 			goto next;
 
-		if (cpu_read_ops(dn, cpu) != 0)
-			goto next;
-
-		if (cpu_ops[cpu]->cpu_init(dn, cpu))
-			goto next;
-
 		pr_debug("cpu logical map 0x%llx\n", hwid);
 		cpu_logical_map(cpu) = hwid;
 next:
@@ -418,12 +429,18 @@ next:
 	}
 
 	/*
-	 * All the cpus that made it to the cpu_logical_map have been
-	 * validated so set them as possible cpus.
+	 * We need to set the cpu_logical_map entries before enabling
+	 * the cpus so that cpu processor description entries (DT cpu nodes
+	 * and ACPI MADT entries) can be retrieved by matching the cpu hwid
+	 * with entries in cpu_logical_map while initializing the cpus.
+	 * If the cpu set-up fails, invalidate the cpu_logical_map entry.
 	 */
-	for (i = 0; i < NR_CPUS; i++)
-		if (cpu_logical_map(i) != INVALID_HWID)
-			set_cpu_possible(i, true);
+	for (i = 1; i < NR_CPUS; i++) {
+		if (cpu_logical_map(i) != INVALID_HWID) {
+			if (smp_cpu_setup(i))
+				cpu_logical_map(i) = INVALID_HWID;
+		}
+	}
 }
 
 void __init smp_prepare_cpus(unsigned int max_cpus)