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ACPI: RISC-V: Add LPI driver

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Enable Low Power Idle (LPI) based cpuidle driver for RISC-V platforms.
It depends on SBI HSM calls for idle state transitions.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20240118062930.245937-3-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Sunil V L 2024-01-18 11:59:29 +05:30 committed by Palmer Dabbelt
parent 6649182a38
commit 4877fc9214
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GPG Key ID: 2E1319F35FBB1889
2 changed files with 83 additions and 1 deletions
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3
drivers/acpi/riscv/Makefile
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@ -1,2 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-y += rhct.o
obj-y += rhct.o
obj-$(CONFIG_ACPI_PROCESSOR_IDLE) += cpuidle.o

81
drivers/acpi/riscv/cpuidle.c Normal file
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@ -0,0 +1,81 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2024, Ventana Micro Systems Inc
* Author: Sunil V L <sunilvl@ventanamicro.com>
*
*/
#include <linux/acpi.h>
#include <acpi/processor.h>
#include <linux/cpu_pm.h>
#include <linux/cpuidle.h>
#include <linux/suspend.h>
#include <asm/cpuidle.h>
#include <asm/sbi.h>
#include <asm/suspend.h>
#define RISCV_FFH_LPI_TYPE_MASK GENMASK_ULL(63, 60)
#define RISCV_FFH_LPI_RSVD_MASK GENMASK_ULL(59, 32)
#define RISCV_FFH_LPI_TYPE_SBI BIT_ULL(60)
static int acpi_cpu_init_idle(unsigned int cpu)
{
int i;
struct acpi_lpi_state *lpi;
struct acpi_processor *pr = per_cpu(processors, cpu);
if (unlikely(!pr || !pr->flags.has_lpi))
return -EINVAL;
if (!riscv_sbi_hsm_is_supported())
return -ENODEV;
if (pr->power.count <= 1)
return -ENODEV;
for (i = 1; i < pr->power.count; i++) {
u32 state;
lpi = &pr->power.lpi_states[i];
/*
* Validate Entry Method as per FFH spec.
* bits[63:60] should be 0x1
* bits[59:32] should be 0x0
* bits[31:0] represent a SBI power_state
*/
if (((lpi->address & RISCV_FFH_LPI_TYPE_MASK) != RISCV_FFH_LPI_TYPE_SBI) ||
(lpi->address & RISCV_FFH_LPI_RSVD_MASK)) {
pr_warn("Invalid LPI entry method %#llx\n", lpi->address);
return -EINVAL;
}
state = lpi->address;
if (!riscv_sbi_suspend_state_is_valid(state)) {
pr_warn("Invalid SBI power state %#x\n", state);
return -EINVAL;
}
}
return 0;
}
int acpi_processor_ffh_lpi_probe(unsigned int cpu)
{
return acpi_cpu_init_idle(cpu);
}
int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
{
u32 state = lpi->address;
if (state & SBI_HSM_SUSP_NON_RET_BIT)
return CPU_PM_CPU_IDLE_ENTER_PARAM(riscv_sbi_hart_suspend,
lpi->index,
state);
else
return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(riscv_sbi_hart_suspend,
lpi->index,
state);
}