Merge patch series "RISC-V: ACPI: Add LPI support"

Sunil V L <sunilvl@ventanamicro.com> says:

This series adds support for Low Power Idle (LPI) on ACPI based
platforms.

LPI is described in the ACPI spec [1]. RISC-V FFH spec required to
enable this is available at [2].

[1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#lpi-low-power-idle-states
[2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v/riscv-ffh.pdf

* b4-shazam-merge:
  ACPI: Enable ACPI_PROCESSOR for RISC-V
  ACPI: RISC-V: Add LPI driver
  cpuidle: RISC-V: Move few functions to arch/riscv

Link: https://lore.kernel.org/r/20240118062930.245937-1-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/suspend.h

@@ -55,4 +55,7 @@ int hibernate_resume_nonboot_cpu_disable(void);
 asmlinkage void hibernate_restore_image(unsigned long resume_satp, unsigned long satp_temp,
 					unsigned long cpu_resume);
 asmlinkage int hibernate_core_restore_code(void);
+bool riscv_sbi_hsm_is_supported(void);
+bool riscv_sbi_suspend_state_is_valid(u32 state);
+int riscv_sbi_hart_suspend(u32 state);
 #endif

arch/riscv/kernel/suspend.c

@@ -128,4 +128,53 @@ static int __init sbi_system_suspend_init(void)
 }
 
 arch_initcall(sbi_system_suspend_init);
+
+static int sbi_suspend_finisher(unsigned long suspend_type,
+				unsigned long resume_addr,
+				unsigned long opaque)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_SUSPEND,
+			suspend_type, resume_addr, opaque, 0, 0, 0);
+
+	return (ret.error) ? sbi_err_map_linux_errno(ret.error) : 0;
+}
+
+int riscv_sbi_hart_suspend(u32 state)
+{
+	if (state & SBI_HSM_SUSP_NON_RET_BIT)
+		return cpu_suspend(state, sbi_suspend_finisher);
+	else
+		return sbi_suspend_finisher(state, 0, 0);
+}
+
+bool riscv_sbi_suspend_state_is_valid(u32 state)
+{
+	if (state > SBI_HSM_SUSPEND_RET_DEFAULT &&
+	    state < SBI_HSM_SUSPEND_RET_PLATFORM)
+		return false;
+
+	if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT &&
+	    state < SBI_HSM_SUSPEND_NON_RET_PLATFORM)
+		return false;
+
+	return true;
+}
+
+bool riscv_sbi_hsm_is_supported(void)
+{
+	/*
+	 * The SBI HSM suspend function is only available when:
+	 * 1) SBI version is 0.3 or higher
+	 * 2) SBI HSM extension is available
+	 */
+	if (sbi_spec_version < sbi_mk_version(0, 3) ||
+	    !sbi_probe_extension(SBI_EXT_HSM)) {
+		pr_info("HSM suspend not available\n");
+		return false;
+	}
+
+	return true;
+}
 #endif /* CONFIG_RISCV_SBI */

drivers/acpi/Kconfig

@@ -286,7 +286,7 @@ config ACPI_CPPC_LIB
 
 config ACPI_PROCESSOR
 	tristate "Processor"
-	depends on X86 || ARM64 || LOONGARCH
+	depends on X86 || ARM64 || LOONGARCH || RISCV
 	select ACPI_PROCESSOR_IDLE
 	select ACPI_CPU_FREQ_PSS if X86 || LOONGARCH
 	select THERMAL

drivers/acpi/riscv/Makefile

@@ -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

drivers/acpi/riscv/cpuidle.c

@@ -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);
+}

drivers/cpuidle/cpuidle-riscv-sbi.c

@@ -73,26 +73,6 @@ static inline bool sbi_is_domain_state_available(void)
 	return data->available;
 }
 
-static int sbi_suspend_finisher(unsigned long suspend_type,
-				unsigned long resume_addr,
-				unsigned long opaque)
-{
-	struct sbiret ret;
-
-	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_SUSPEND,
-			suspend_type, resume_addr, opaque, 0, 0, 0);
-
-	return (ret.error) ? sbi_err_map_linux_errno(ret.error) : 0;
-}
-
-static int sbi_suspend(u32 state)
-{
-	if (state & SBI_HSM_SUSP_NON_RET_BIT)
-		return cpu_suspend(state, sbi_suspend_finisher);
-	else
-		return sbi_suspend_finisher(state, 0, 0);
-}
-
 static __cpuidle int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
 					     struct cpuidle_driver *drv, int idx)
 {
@@ -100,9 +80,9 @@ static __cpuidle int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
 	u32 state = states[idx];
 
 	if (state & SBI_HSM_SUSP_NON_RET_BIT)
-		return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, state);
+		return CPU_PM_CPU_IDLE_ENTER_PARAM(riscv_sbi_hart_suspend, idx, state);
 	else
-		return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(sbi_suspend,
+		return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(riscv_sbi_hart_suspend,
 							     idx, state);
 }
 
@@ -133,7 +113,7 @@ static __cpuidle int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
 	else
 		state = states[idx];
 
-	ret = sbi_suspend(state) ? -1 : idx;
+	ret = riscv_sbi_hart_suspend(state) ? -1 : idx;
 
 	ct_cpuidle_exit();
 
@@ -206,17 +186,6 @@ static const struct of_device_id sbi_cpuidle_state_match[] = {
 	{ },
 };
 
-static bool sbi_suspend_state_is_valid(u32 state)
-{
-	if (state > SBI_HSM_SUSPEND_RET_DEFAULT &&
-	    state < SBI_HSM_SUSPEND_RET_PLATFORM)
-		return false;
-	if (state > SBI_HSM_SUSPEND_NON_RET_DEFAULT &&
-	    state < SBI_HSM_SUSPEND_NON_RET_PLATFORM)
-		return false;
-	return true;
-}
-
 static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
 {
 	int err = of_property_read_u32(np, "riscv,sbi-suspend-param", state);
@@ -226,7 +195,7 @@ static int sbi_dt_parse_state_node(struct device_node *np, u32 *state)
 		return err;
 	}
 
-	if (!sbi_suspend_state_is_valid(*state)) {
+	if (!riscv_sbi_suspend_state_is_valid(*state)) {
 		pr_warn("Invalid SBI suspend state %#x\n", *state);
 		return -EINVAL;
 	}
@@ -607,16 +576,8 @@ static int __init sbi_cpuidle_init(void)
 	int ret;
 	struct platform_device *pdev;
 
-	/*
-	 * The SBI HSM suspend function is only available when:
-	 * 1) SBI version is 0.3 or higher
-	 * 2) SBI HSM extension is available
-	 */
-	if ((sbi_spec_version < sbi_mk_version(0, 3)) ||
-	    !sbi_probe_extension(SBI_EXT_HSM)) {
-		pr_info("HSM suspend not available\n");
+	if (!riscv_sbi_hsm_is_supported())
 		return 0;
-	}
 
 	ret = platform_driver_register(&sbi_cpuidle_driver);
 	if (ret)