Re: [PATCH v11 6/8] cpuidle: Add RISC-V SBI CPU idle driver

Jessica Clarke
2022-02-16T13:45:18Z

On 16 Feb 2022, at 08:09, Atish Patra <atishp@atishpatra.org> wrote:
>
> On Wed, Feb 9, 2022 at 9:51 PM Anup Patel <apatel@ventanamicro.com> wrote:
>>
>> From: Anup Patel <anup.patel@wdc.com>
>>
>> The RISC-V SBI HSM extension provides HSM suspend call which can
>> be used by Linux RISC-V to enter platform specific low-power state.
>>
>> This patch adds a CPU idle driver based on RISC-V SBI calls which
>> will populate idle states from device tree and use SBI calls to
>> entry these idle states.
>>
>> Signed-off-by: Anup Patel <anup.patel@wdc.com>
>> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
>> ---
>> MAINTAINERS | 7 +
>> drivers/cpuidle/Kconfig | 5 +
>> drivers/cpuidle/Kconfig.riscv | 15 +
>> drivers/cpuidle/Makefile | 4 +
>> drivers/cpuidle/cpuidle-riscv-sbi.c | 627 ++++++++++++++++++++++++++++
>> 5 files changed, 658 insertions(+)
>> create mode 100644 drivers/cpuidle/Kconfig.riscv
>> create mode 100644 drivers/cpuidle/cpuidle-riscv-sbi.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 39ece23e8d93..2ff0055a26a7 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -5058,6 +5058,13 @@ S: Supported
>> F: drivers/cpuidle/dt_idle_genpd.c
>> F: drivers/cpuidle/dt_idle_genpd.h
>>
>> +CPUIDLE DRIVER - RISC-V SBI
>> +M: Anup Patel <anup@brainfault.org>
>> +L: linux-pm@vger.kernel.org
>> +L: linux-riscv@lists.infradead.org
>> +S: Maintained
>> +F: drivers/cpuidle/cpuidle-riscv-sbi.c
>> +
>> CRAMFS FILESYSTEM
>> M: Nicolas Pitre <nico@fluxnic.net>
>> S: Maintained
>> diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
>> index f1afe7ab6b54..ff71dd662880 100644
>> --- a/drivers/cpuidle/Kconfig
>> +++ b/drivers/cpuidle/Kconfig
>> @@ -66,6 +66,11 @@ depends on PPC
>> source "drivers/cpuidle/Kconfig.powerpc"
>> endmenu
>>
>> +menu "RISC-V CPU Idle Drivers"
>> +depends on RISCV
>> +source "drivers/cpuidle/Kconfig.riscv"
>> +endmenu
>> +
>> config HALTPOLL_CPUIDLE
>> tristate "Halt poll cpuidle driver"
>> depends on X86 && KVM_GUEST
>> diff --git a/drivers/cpuidle/Kconfig.riscv b/drivers/cpuidle/Kconfig.riscv
>> new file mode 100644
>> index 000000000000..78518c26af74
>> --- /dev/null
>> +++ b/drivers/cpuidle/Kconfig.riscv
>> @@ -0,0 +1,15 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +#
>> +# RISC-V CPU Idle drivers
>> +#
>> +
>> +config RISCV_SBI_CPUIDLE
>> + bool "RISC-V SBI CPU idle Driver"
>> + depends on RISCV_SBI
>> + select DT_IDLE_STATES
>> + select CPU_IDLE_MULTIPLE_DRIVERS
>> + select DT_IDLE_GENPD if PM_GENERIC_DOMAINS_OF
>> + help
>> + Select this option to enable RISC-V SBI firmware based CPU idle
>> + driver for RISC-V systems. This drivers also supports hierarchical
>> + DT based layout of the idle state.
>> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
>> index 11a26cef279f..d103342b7cfc 100644
>> --- a/drivers/cpuidle/Makefile
>> +++ b/drivers/cpuidle/Makefile
>> @@ -35,3 +35,7 @@ obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o
>> # POWERPC drivers
>> obj-$(CONFIG_PSERIES_CPUIDLE) += cpuidle-pseries.o
>> obj-$(CONFIG_POWERNV_CPUIDLE) += cpuidle-powernv.o
>> +
>> +###############################################################################
>> +# RISC-V drivers
>> +obj-$(CONFIG_RISCV_SBI_CPUIDLE) += cpuidle-riscv-sbi.o
>> diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
>> new file mode 100644
>> index 000000000000..b459eda2cd37
>> --- /dev/null
>> +++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
>> @@ -0,0 +1,627 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * RISC-V SBI CPU idle driver.
>> + *
>> + * Copyright (c) 2021 Western Digital Corporation or its affiliates.
>> + * Copyright (c) 2022 Ventana Micro Systems Inc.
>> + */
>> +
>> +#define pr_fmt(fmt) "cpuidle-riscv-sbi: " fmt
>> +
>> +#include <linux/cpuidle.h>
>> +#include <linux/cpumask.h>
>> +#include <linux/cpu_pm.h>
>> +#include <linux/cpu_cooling.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/slab.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_domain.h>
>> +#include <linux/pm_runtime.h>
>> +#include <asm/cpuidle.h>
>> +#include <asm/sbi.h>
>> +#include <asm/suspend.h>
>> +
>> +#include "dt_idle_states.h"
>> +#include "dt_idle_genpd.h"
>> +
>> +struct sbi_cpuidle_data {
>> + u32 *states;
>> + struct device *dev;
>> +};
>> +
>> +struct sbi_domain_state {
>> + bool available;
>> + u32 state;
>> +};
>> +
>> +static DEFINE_PER_CPU_READ_MOSTLY(struct sbi_cpuidle_data, sbi_cpuidle_data);
>> +static DEFINE_PER_CPU(struct sbi_domain_state, domain_state);
>> +static bool sbi_cpuidle_use_osi;
>> +static bool sbi_cpuidle_use_cpuhp;
>> +static bool sbi_cpuidle_pd_allow_domain_state;
>> +
>> +static inline void sbi_set_domain_state(u32 state)
>> +{
>> + struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
>> +
>> + data->available = true;
>> + data->state = state;
>> +}
>> +
>> +static inline u32 sbi_get_domain_state(void)
>> +{
>> + struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
>> +
>> + return data->state;
>> +}
>> +
>> +static inline void sbi_clear_domain_state(void)
>> +{
>> + struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
>> +
>> + data->available = false;
>> +}
>> +
>> +static inline bool sbi_is_domain_state_available(void)
>> +{
>> + struct sbi_domain_state *data = this_cpu_ptr(&domain_state);
>> +
>> + 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 int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
>> + struct cpuidle_driver *drv, int idx)
>> +{
>> + u32 *states = __this_cpu_read(sbi_cpuidle_data.states);
>> +
>> + return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, states[idx]);
>> +}
>> +
>> +static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
>> + struct cpuidle_driver *drv, int idx,
>> + bool s2idle)
>> +{
>> + struct sbi_cpuidle_data *data = this_cpu_ptr(&sbi_cpuidle_data);
>> + u32 *states = data->states;
>> + struct device *pd_dev = data->dev;
>> + u32 state;
>> + int ret;
>> +
>> + ret = cpu_pm_enter();
>> + if (ret)
>> + return -1;
>> +
>> + /* Do runtime PM to manage a hierarchical CPU toplogy. */
>> + rcu_irq_enter_irqson();
>> + if (s2idle)
>> + dev_pm_genpd_suspend(pd_dev);
>> + else
>> + pm_runtime_put_sync_suspend(pd_dev);
>> + rcu_irq_exit_irqson();
>> +
>> + if (sbi_is_domain_state_available())
>> + state = sbi_get_domain_state();
>> + else
>> + state = states[idx];
>> +
>> + ret = sbi_suspend(state) ? -1 : idx;
>> +
>> + rcu_irq_enter_irqson();
>> + if (s2idle)
>> + dev_pm_genpd_resume(pd_dev);
>> + else
>> + pm_runtime_get_sync(pd_dev);
>> + rcu_irq_exit_irqson();
>> +
>> + cpu_pm_exit();
>> +
>> + /* Clear the domain state to start fresh when back from idle. */
>> + sbi_clear_domain_state();
>> + return ret;
>> +}
>> +
>> +static int sbi_enter_domain_idle_state(struct cpuidle_device *dev,
>> + struct cpuidle_driver *drv, int idx)
>> +{
>> + return __sbi_enter_domain_idle_state(dev, drv, idx, false);
>> +}
>> +
>> +static int sbi_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
>> + struct cpuidle_driver *drv,
>> + int idx)
>> +{
>> + return __sbi_enter_domain_idle_state(dev, drv, idx, true);
>> +}
>> +
>> +static int sbi_cpuidle_cpuhp_up(unsigned int cpu)
>> +{
>> + struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
>> +
>> + if (pd_dev)
>> + pm_runtime_get_sync(pd_dev);
>> +
>> + return 0;
>> +}
>> +
>> +static int sbi_cpuidle_cpuhp_down(unsigned int cpu)
>> +{
>> + struct device *pd_dev = __this_cpu_read(sbi_cpuidle_data.dev);
>> +
>> + if (pd_dev) {
>> + pm_runtime_put_sync(pd_dev);
>> + /* Clear domain state to start fresh at next online. */
>> + sbi_clear_domain_state();
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void sbi_idle_init_cpuhp(void)
>> +{
>> + int err;
>> +
>> + if (!sbi_cpuidle_use_cpuhp)
>> + return;
>> +
>> + err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
>> + "cpuidle/sbi:online",
>> + sbi_cpuidle_cpuhp_up,
>> + sbi_cpuidle_cpuhp_down);
>> + if (err)
>> + pr_warn("Failed %d while setup cpuhp state\n", err);
>> +}
>> +
>> +static const struct of_device_id sbi_cpuidle_state_match[] = {
>> + { .compatible = "riscv,idle-state",
>> + .data = sbi_cpuidle_enter_state },
>> + { },
>> +};
>> +
>> +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);
>> +
>> + if (err) {
>> + pr_warn("%pOF missing riscv,sbi-suspend-param property\n", np);
>> + return err;
>> + }
>> +
>> + if (!sbi_suspend_state_is_valid(*state)) {
>> + pr_warn("Invalid SBI suspend state %#x\n", *state);
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int sbi_dt_cpu_init_topology(struct cpuidle_driver *drv,
>> + struct sbi_cpuidle_data *data,
>> + unsigned int state_count, int cpu)
>> +{
>> + /* Currently limit the hierarchical topology to be used in OSI mode. */
>> + if (!sbi_cpuidle_use_osi)
>> + return 0;
>> +
>> + data->dev = dt_idle_attach_cpu(cpu, "sbi");
>> + if (IS_ERR_OR_NULL(data->dev))
>> + return PTR_ERR_OR_ZERO(data->dev);
>> +
>> + /*
>> + * Using the deepest state for the CPU to trigger a potential selection
>> + * of a shared state for the domain, assumes the domain states are all
>> + * deeper states.
>> + */
>> + drv->states[state_count - 1].enter = sbi_enter_domain_idle_state;
>> + drv->states[state_count - 1].enter_s2idle =
>> + sbi_enter_s2idle_domain_idle_state;
>> + sbi_cpuidle_use_cpuhp = true;
>> +
>> + return 0;
>> +}
>> +
>> +static int sbi_cpuidle_dt_init_states(struct device *dev,
>> + struct cpuidle_driver *drv,
>> + unsigned int cpu,
>> + unsigned int state_count)
>> +{
>> + struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
>> + struct device_node *state_node;
>> + struct device_node *cpu_node;
>> + u32 *states;
>> + int i, ret;
>> +
>> + cpu_node = of_cpu_device_node_get(cpu);
>> + if (!cpu_node)
>> + return -ENODEV;
>> +
>> + states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
>> + if (!states) {
>> + ret = -ENOMEM;
>> + goto fail;
>> + }
>> +
>> + /* Parse SBI specific details from state DT nodes */
>> + for (i = 1; i < state_count; i++) {
>> + state_node = of_get_cpu_state_node(cpu_node, i - 1);
>> + if (!state_node)
>> + break;
>> +
>> + ret = sbi_dt_parse_state_node(state_node, &states[i]);
>> + of_node_put(state_node);
>> +
>> + if (ret)
>> + return ret;
>> +
>> + pr_debug("sbi-state %#x index %d\n", states[i], i);
>> + }
>> + if (i != state_count) {
>> + ret = -ENODEV;
>> + goto fail;
>> + }
>> +
>> + /* Initialize optional data, used for the hierarchical topology. */
>> + ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /* Store states in the per-cpu struct. */
>> + data->states = states;
>> +
>> +fail:
>> + of_node_put(cpu_node);
>> +
>> + return ret;
>> +}
>> +
>> +static void sbi_cpuidle_deinit_cpu(int cpu)
>> +{
>> + struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
>> +
>> + dt_idle_detach_cpu(data->dev);
>> + sbi_cpuidle_use_cpuhp = false;
>> +}
>> +
>> +static int sbi_cpuidle_init_cpu(struct device *dev, int cpu)
>> +{
>> + struct cpuidle_driver *drv;
>> + unsigned int state_count = 0;
>> + int ret = 0;
>> +
>> + drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
>> + if (!drv)
>> + return -ENOMEM;
>> +
>> + drv->name = "sbi_cpuidle";
>> + drv->owner = THIS_MODULE;
>> + drv->cpumask = (struct cpumask *)cpumask_of(cpu);
>> +
>> + /* RISC-V architectural WFI to be represented as state index 0. */
>> + drv->states[0].enter = sbi_cpuidle_enter_state;
>> + drv->states[0].exit_latency = 1;
>> + drv->states[0].target_residency = 1;
>> + drv->states[0].power_usage = UINT_MAX;
>> + strcpy(drv->states[0].name, "WFI");
>> + strcpy(drv->states[0].desc, "RISC-V WFI");
>> +
>> + /*
>> + * If no DT idle states are detected (ret == 0) let the driver
>> + * initialization fail accordingly since there is no reason to
>> + * initialize the idle driver if only wfi is supported, the
>> + * default archictectural back-end already executes wfi
>> + * on idle entry.
>> + */
>> + ret = dt_init_idle_driver(drv, sbi_cpuidle_state_match, 1);
>> + if (ret <= 0) {
>> + pr_debug("HART%ld: failed to parse DT idle states\n",
>> + cpuid_to_hartid_map(cpu));
>> + return ret ? : -ENODEV;
>> + }
>> + state_count = ret + 1; /* Include WFI state as well */
>> +
>> + /* Initialize idle states from DT. */
>> + ret = sbi_cpuidle_dt_init_states(dev, drv, cpu, state_count);
>> + if (ret) {
>> + pr_err("HART%ld: failed to init idle states\n",
>> + cpuid_to_hartid_map(cpu));
>> + return ret;
>> + }
>> +
>> + ret = cpuidle_register(drv, NULL);
>> + if (ret)
>> + goto deinit;
>> +
>> + cpuidle_cooling_register(drv);
>> +
>> + return 0;
>> +deinit:
>> + sbi_cpuidle_deinit_cpu(cpu);
>> + return ret;
>> +}
>> +
>> +static void sbi_cpuidle_domain_sync_state(struct device *dev)
>> +{
>> + /*
>> + * All devices have now been attached/probed to the PM domain
>> + * topology, hence it's fine to allow domain states to be picked.
>> + */
>> + sbi_cpuidle_pd_allow_domain_state = true;
>> +}
>> +
>> +#ifdef CONFIG_DT_IDLE_GENPD
>> +
>> +static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)
>> +{
>> + struct genpd_power_state *state = &pd->states[pd->state_idx];
>> + u32 *pd_state;
>> +
>> + if (!state->data)
>> + return 0;
>> +
>> + if (!sbi_cpuidle_pd_allow_domain_state)
>> + return -EBUSY;
>> +
>> + /* OSI mode is enabled, set the corresponding domain state. */
>> + pd_state = state->data;
>> + sbi_set_domain_state(*pd_state);
>> +
>> + return 0;
>> +}
>> +
>> +struct sbi_pd_provider {
>> + struct list_head link;
>> + struct device_node *node;
>> +};
>> +
>> +static LIST_HEAD(sbi_pd_providers);
>> +
>> +static int sbi_pd_init(struct device_node *np)
>> +{
>> + struct generic_pm_domain *pd;
>> + struct sbi_pd_provider *pd_provider;
>> + struct dev_power_governor *pd_gov;
>> + int ret = -ENOMEM, state_count = 0;
>> +
>> + pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
>> + if (!pd)
>> + goto out;
>> +
>> + pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
>> + if (!pd_provider)
>> + goto free_pd;
>> +
>> + pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
>> +
>> + /* Allow power off when OSI is available. */
>> + if (sbi_cpuidle_use_osi)
>> + pd->power_off = sbi_cpuidle_pd_power_off;
>> + else
>> + pd->flags |= GENPD_FLAG_ALWAYS_ON;
>> +
>> + /* Use governor for CPU PM domains if it has some states to manage. */
>> + pd_gov = state_count > 0 ? &pm_domain_cpu_gov : NULL;
>> +
>> + ret = pm_genpd_init(pd, pd_gov, false);
>> + if (ret)
>> + goto free_pd_prov;
>> +
>> + ret = of_genpd_add_provider_simple(np, pd);
>> + if (ret)
>> + goto remove_pd;
>> +
>> + pd_provider->node = of_node_get(np);
>> + list_add(&pd_provider->link, &sbi_pd_providers);
>> +
>> + pr_debug("init PM domain %s\n", pd->name);
>> + return 0;
>> +
>> +remove_pd:
>> + pm_genpd_remove(pd);
>> +free_pd_prov:
>> + kfree(pd_provider);
>> +free_pd:
>> + dt_idle_pd_free(pd);
>> +out:
>> + pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
>> + return ret;
>> +}
>> +
>> +static void sbi_pd_remove(void)
>> +{
>> + struct sbi_pd_provider *pd_provider, *it;
>> + struct generic_pm_domain *genpd;
>> +
>> + list_for_each_entry_safe(pd_provider, it, &sbi_pd_providers, link) {
>> + of_genpd_del_provider(pd_provider->node);
>> +
>> + genpd = of_genpd_remove_last(pd_provider->node);
>> + if (!IS_ERR(genpd))
>> + kfree(genpd);
>> +
>> + of_node_put(pd_provider->node);
>> + list_del(&pd_provider->link);
>> + kfree(pd_provider);
>> + }
>> +}
>> +
>> +static int sbi_genpd_probe(struct device_node *np)
>> +{
>> + struct device_node *node;
>> + int ret = 0, pd_count = 0;
>> +
>> + if (!np)
>> + return -ENODEV;
>> +
>> + /*
>> + * Parse child nodes for the "#power-domain-cells" property and
>> + * initialize a genpd/genpd-of-provider pair when it's found.
>> + */
>> + for_each_child_of_node(np, node) {
>> + if (!of_find_property(node, "#power-domain-cells", NULL))
>> + continue;
>> +
>> + ret = sbi_pd_init(node);
>> + if (ret)
>> + goto put_node;
>> +
>> + pd_count++;
>> + }
>> +
>> + /* Bail out if not using the hierarchical CPU topology. */
>> + if (!pd_count)
>> + goto no_pd;
>> +
>> + /* Link genpd masters/subdomains to model the CPU topology. */
>> + ret = dt_idle_pd_init_topology(np);
>> + if (ret)
>> + goto remove_pd;
>> +
>> + return 0;
>> +
>> +put_node:
>> + of_node_put(node);
>> +remove_pd:
>> + sbi_pd_remove();
>> + pr_err("failed to create CPU PM domains ret=%d\n", ret);
>> +no_pd:
>> + return ret;
>> +}
>> +
>> +#else
>> +
>> +static inline int sbi_genpd_probe(struct device_node *np)
>> +{
>> + return 0;
>> +}
>> +
>> +#endif
>> +
>> +static int sbi_cpuidle_probe(struct platform_device *pdev)
>> +{
>> + int cpu, ret;
>> + struct cpuidle_driver *drv;
>> + struct cpuidle_device *dev;
>> + struct device_node *np, *pds_node;
>> +
>> + /* Detect OSI support based on CPU DT nodes */
>> + sbi_cpuidle_use_osi = true;
>> + for_each_possible_cpu(cpu) {
>> + np = of_cpu_device_node_get(cpu);
>> + if (np &&
>> + of_find_property(np, "power-domains", NULL) &&
>> + of_find_property(np, "power-domain-names", NULL)) {
>> + continue;
>> + } else {
>> + sbi_cpuidle_use_osi = false;
>> + break;
>> + }
>> + }
>> +
>> + /* Populate generic power domains from DT nodes */
>> + pds_node = of_find_node_by_path("/cpus/power-domains");
>> + if (pds_node) {
>> + ret = sbi_genpd_probe(pds_node);
>> + of_node_put(pds_node);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + /* Initialize CPU idle driver for each CPU */
>> + for_each_possible_cpu(cpu) {
>> + ret = sbi_cpuidle_init_cpu(&pdev->dev, cpu);
>> + if (ret) {
>> + pr_debug("HART%ld: idle driver init failed\n",
>> + cpuid_to_hartid_map(cpu));
>> + goto out_fail;
>> + }
>> + }
>> +
>> + /* Setup CPU hotplut notifiers */
>> + sbi_idle_init_cpuhp();
>> +
>> + pr_info("idle driver registered for all CPUs\n");
>> +
>> + return 0;
>> +
>> +out_fail:
>> + while (--cpu >= 0) {
>> + dev = per_cpu(cpuidle_devices, cpu);
>> + drv = cpuidle_get_cpu_driver(dev);
>> + cpuidle_unregister(drv);
>> + sbi_cpuidle_deinit_cpu(cpu);
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static struct platform_driver sbi_cpuidle_driver = {
>> + .probe = sbi_cpuidle_probe,
>> + .driver = {
>> + .name = "sbi-cpuidle",
>> + .sync_state = sbi_cpuidle_domain_sync_state,
>> + },
>> +};
>> +
>> +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) <= 0) {
>> + pr_info("HSM suspend not available\n");
>> + return 0;
>> + }
>> +
>> + ret = platform_driver_register(&sbi_cpuidle_driver);
>> + if (ret)
>> + return ret;
>> +
>> + pdev = platform_device_register_simple("sbi-cpuidle",
>> + -1, NULL, 0);
>> + if (IS_ERR(pdev)) {
>> + platform_driver_unregister(&sbi_cpuidle_driver);
>> + return PTR_ERR(pdev);
>> + }
>> +
>> + return 0;
>> +}
>> +device_initcall(sbi_cpuidle_init);
>> --
>> 2.25.1
>>
>
> For the SBI part,
> Acked-by: Atish Patra <atishp@rivosinc.com>
>
> FYI..
> SBI HSM suspend was included in SBI v0.3. The current version of the
> SBI specification (v1.0-rc2)
> is already frozen as per the RVI guidelines. All the comments received
> during the public review period
> have been addressed as well.

Yet not all comments from *before* the public review period.

Jess