[PATCH v3 2/7] RISC-V: split early & late of_node to hartid mapping

Conor Dooley
2023-06-07T20:29:08Z

Some back and forth with Drew [1] about riscv_fill_hwcap() resulted in
the realisation that it is not very useful to parse the DT & perform
validation of riscv,isa every time we would like to get the id for a
hart.

Although it is no longer called in riscv_fill_hwcap(),
riscv_of_processor_hartid() is called in several other places.
Notably in setup_smp() it forms part of the logic for filling the mask
of possible CPUs. Since a possible CPU must have passed this basic
validation of riscv,isa, a repeat validation is not required.

Rename riscv_of_processor_id() to riscv_early_of_processor_id(),
which will be called from setup_smp() & introduce a new
riscv_of_processor_id() which makes use of the pre-populated mask of
possible cpus.

Link: https://lore.kernel.org/linux-riscv/xvdswl3iyikwvamny7ikrxo2ncuixshtg3f6uucjahpe3xpc5c@ud4cz4fkg5dj/ [1]
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
arch/riscv/include/asm/processor.h | 1 +
arch/riscv/kernel/cpu.c | 22 +++++++++++++++++++++-
arch/riscv/kernel/smpboot.c | 2 +-
3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 94a0590c6971..3479f9fca4b0 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -75,6 +75,7 @@ static inline void wait_for_interrupt(void)

struct device_node;
int riscv_of_processor_hartid(struct device_node *node, unsigned long *hartid);
+int riscv_early_of_processor_hartid(struct device_node *node, unsigned long *hartid);
int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid);

extern void riscv_fill_hwcap(void);
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 637263f9a7b9..8025de06edb7 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -22,6 +22,26 @@
* isn't an enabled and valid RISC-V hart node.
*/
int riscv_of_processor_hartid(struct device_node *node, unsigned long *hart)
+{
+ int cpu;
+
+ *hart = (unsigned long)of_get_cpu_hwid(node, 0);
+ if (*hart == ~0UL) {
+ pr_warn("Found CPU without hart ID\n");
+ return -ENODEV;
+ }
+
+ cpu = riscv_hartid_to_cpuid(*hart);
+ if (cpu < 0)
+ return cpu;
+
+ if (!cpu_possible(cpu))
+ return -ENODEV;
+
+ return 0;
+}
+
+int riscv_early_of_processor_hartid(struct device_node *node, unsigned long *hart)
{
const char *isa;

@@ -30,7 +50,7 @@ int riscv_of_processor_hartid(struct device_node *node, unsigned long *hart)
return -ENODEV;
}

- *hart = (unsigned long) of_get_cpu_hwid(node, 0);
+ *hart = (unsigned long)of_get_cpu_hwid(node, 0);
if (*hart == ~0UL) {
pr_warn("Found CPU without hart ID\n");
return -ENODEV;
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 67bc5ef3e8b2..3f42331c8912 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -148,7 +148,7 @@ static void __init of_parse_and_init_cpus(void)
cpu_set_ops(0);

for_each_of_cpu_node(dn) {
- rc = riscv_of_processor_hartid(dn, &hart);
+ rc = riscv_early_of_processor_hartid(dn, &hart);
if (rc < 0)
continue;

--
2.39.2