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

Commit Message

Conor Dooley June 7, 2023, 8:28 p.m. UTC

From: Conor Dooley <[e-mail]>

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 <[e-mail]>
Signed-off-by: Conor Dooley <[e-mail]>
---
 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(-)

Comments

Sunil V L June 12, 2023, 7:31 a.m. UTC | #1

On Wed, Jun 07, 2023 at 09:28:26PM +0100, Conor Dooley wrote:
> From: Conor Dooley <[e-mail]>
> 
> 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 <[e-mail]>
> Signed-off-by: Conor Dooley <[e-mail]>
> ---
Reviewed-by: Sunil V L <[e-mail]>

Patch

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;