[PATCH V4 18/23] RISC-V: time.c: Add ACPI support for time_init()

Sunil V L
2023-04-04T18:22:54Z

On ACPI based platforms, timer related information is
available in RHCT. Add ACPI based probe support to the
timer initialization.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
---
arch/riscv/kernel/time.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c
index babaf3b48ba8..23641e82a9df 100644
--- a/arch/riscv/kernel/time.c
+++ b/arch/riscv/kernel/time.c
@@ -4,6 +4,7 @@
* Copyright (C) 2017 SiFive
*/

+#include <linux/acpi.h>
#include <linux/of_clk.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
@@ -18,17 +19,29 @@ EXPORT_SYMBOL_GPL(riscv_timebase);
void __init time_init(void)
{
struct device_node *cpu;
+ struct acpi_table_rhct *rhct;
+ acpi_status status;
u32 prop;

- cpu = of_find_node_by_path("/cpus");
- if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
- panic(KERN_WARNING "RISC-V system with no 'timebase-frequency' in DTS\n");
- of_node_put(cpu);
- riscv_timebase = prop;
+ if (acpi_disabled) {
+ cpu = of_find_node_by_path("/cpus");
+ if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
+ panic("RISC-V system with no 'timebase-frequency' in DTS\n");
+
+ of_node_put(cpu);
+ riscv_timebase = prop;
+ of_clk_init(NULL);
+ } else {
+ status = acpi_get_table(ACPI_SIG_RHCT, 0, (struct acpi_table_header **)&rhct);
+ if (ACPI_FAILURE(status))
+ panic("RISC-V ACPI system with no RHCT table\n");
+
+ riscv_timebase = rhct->time_base_freq;
+ acpi_put_table((struct acpi_table_header *)rhct);
+ }

lpj_fine = riscv_timebase / HZ;

- of_clk_init(NULL);
timer_probe();

tick_setup_hrtimer_broadcast();
--
2.34.1