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SubjectRe: [PATCH v10 18/27] drivers: firmware: psci: Add support for PM domains using genpd
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On 29/11/2018 18:46, Ulf Hansson wrote:
> When the hierarchical CPU topology layout is used in DT, we need to setup
> the corresponding PM domain data structures, as to allow a CPU and a group
> of CPUs to be power managed accordingly. Let's enable this by deploying
> support through the genpd interface.
>
> Additionally, when the OS initiated mode is supported by the PSCI FW, let's
> also parse the domain idle states DT bindings as to make genpd responsible
> for the state selection, when the states are compatible with
> "domain-idle-state". Otherwise, when only Platform Coordinated mode is
> supported, we rely solely on the state selection to be managed through the
> regular cpuidle framework.
>
> If the initialization of the PM domain data structures succeeds and the OS
> initiated mode is supported, we try to switch to it. In case it fails,
> let's fall back into a degraded mode, rather than bailing out and returning
> an error code.
>
> Due to that the OS initiated mode may become enabled, we need to adjust to
> maintain backwards compatibility for a kernel started through a kexec call.
> Do this by explicitly switch to Platform Coordinated mode during boot.
>
> To try to initiate the PM domain data structures, the PSCI driver shall
> call the new function, psci_dt_init_pm_domains(). However, this is done
> from following changes.
>
> Cc: Lina Iyer <ilina@codeaurora.org>
> Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>
> Changes in V10:
> - Enable the PM domains to be used for both PC and OSI mode.
> - Fixup error paths.
> - Move the management of kexec started kernels into this patch.
> - Rewrite changelog.
>
> ---
> drivers/firmware/psci/Makefile | 2 +-
> drivers/firmware/psci/psci.c | 7 +-
> drivers/firmware/psci/psci.h | 6 +
> drivers/firmware/psci/psci_pm_domain.c | 262 +++++++++++++++++++++++++
> 4 files changed, 275 insertions(+), 2 deletions(-)
> create mode 100644 drivers/firmware/psci/psci_pm_domain.c
>
> diff --git a/drivers/firmware/psci/Makefile b/drivers/firmware/psci/Makefile
> index 1956b882470f..ff300f1fec86 100644
> --- a/drivers/firmware/psci/Makefile
> +++ b/drivers/firmware/psci/Makefile
> @@ -1,4 +1,4 @@
> # SPDX-License-Identifier: GPL-2.0
> #
> -obj-$(CONFIG_ARM_PSCI_FW) += psci.o
> +obj-$(CONFIG_ARM_PSCI_FW) += psci.o psci_pm_domain.o

Same comment as 17/27.

+obj-$(CONFIG_PSCI_IDLE) += psci_pm_domain.o

> obj-$(CONFIG_ARM_PSCI_CHECKER) += psci_checker.o
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index 623591b541a4..19af2093151b 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -704,9 +704,14 @@ static int __init psci_1_0_init(struct device_node *np)
> if (err)
> return err;
>
> - if (psci_has_osi_support())
> + if (psci_has_osi_support()) {
> pr_info("OSI mode supported.\n");
>
> + /* Make sure we default to PC mode. */
> + invoke_psci_fn(PSCI_1_0_FN_SET_SUSPEND_MODE,
> + PSCI_1_0_SUSPEND_MODE_PC, 0, 0);
> + }
> +
> return 0;
> }
>
> diff --git a/drivers/firmware/psci/psci.h b/drivers/firmware/psci/psci.h
> index 7d9d38fd57e1..8cf6d7206fab 100644
> --- a/drivers/firmware/psci/psci.h
> +++ b/drivers/firmware/psci/psci.h
> @@ -11,4 +11,10 @@ void psci_set_domain_state(u32 state);
> bool psci_has_osi_support(void);
> int psci_dt_parse_state_node(struct device_node *np, u32 *state);
>
> +#ifdef CONFIG_CPU_IDLE

Same comment as 17/27 for the config option.

> +int psci_dt_init_pm_domains(struct device_node *np);
> +#else
> +static inline int psci_dt_init_pm_domains(struct device_node *np) { return 0; }
> +#endif
> +
> #endif /* __PSCI_H */
> diff --git a/drivers/firmware/psci/psci_pm_domain.c b/drivers/firmware/psci/psci_pm_domain.c
> new file mode 100644
> index 000000000000..d0dc38e96f85
> --- /dev/null
> +++ b/drivers/firmware/psci/psci_pm_domain.c
> @@ -0,0 +1,262 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * PM domains for CPUs via genpd - managed by PSCI.
> + *
> + * Copyright (C) 2018 Linaro Ltd.
> + * Author: Ulf Hansson <ulf.hansson@linaro.org>
> + *
> + */
> +
> +#define pr_fmt(fmt) "psci: " fmt
> +
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/pm_domain.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +
> +#include "psci.h"
> +
> +#ifdef CONFIG_CPU_IDLE

Same comment as 17/27 for the config option. This condition should go away.

> +struct psci_pd_provider {
> + struct list_head link;
> + struct device_node *node;
> +};
> +
> +static LIST_HEAD(psci_pd_providers);
> +static bool osi_mode_enabled;
> +
> +static int psci_pd_power_off(struct generic_pm_domain *pd)
> +{
> + struct genpd_power_state *state = &pd->states[pd->state_idx];
> + u32 *pd_state;
> + u32 composite_pd_state;
> +
> + /* If we have failed to enable OSI mode, then abort power off. */
> + if (psci_has_osi_support() && !osi_mode_enabled)
> + return -EBUSY;

I'm not sure EBUSY is the best error code to describe this situation.
May be ENOTSUP ?

However, how possible is it to pass in this function if the OSI mode was
not enabled ?

> + if (!state->data)
> + return 0;
> +
> + /* When OSI mode is enabled, set the corresponding domain state. */
> + pd_state = state->data;
> + composite_pd_state = *pd_state | psci_get_domain_state();
> + psci_set_domain_state(composite_pd_state);
> +
> + return 0;
> +}
> +
> +static int psci_pd_parse_state_nodes(struct genpd_power_state *states,
> + int state_count)

__init ?

> +{
> + int i, ret;
> + u32 psci_state, *psci_state_buf;
> +
> + for (i = 0; i < state_count; i++) {
> + ret = psci_dt_parse_state_node(to_of_node(states[i].fwnode),
> + &psci_state);
> + if (ret)
> + goto free_state;
> +
> + psci_state_buf = kmalloc(sizeof(u32), GFP_KERNEL);
> + if (!psci_state_buf) {
> + ret = -ENOMEM;
> + goto free_state;
> + }
> + *psci_state_buf = psci_state;
> + states[i].data = psci_state_buf;
> + }
> +
> + return 0;
> +
> +free_state:
> + while (i >= 0) {
> + kfree(states[i].data);
> + i--;
> + }

for (; i >= 0; i--)

> + return ret;
> +}
> +
> +static int psci_pd_parse_states(struct device_node *np,
> + struct genpd_power_state **states, int *state_count)

__init ?

> +{
> + int ret;
> +
> + /* Parse the domain idle states. */
> + ret = of_genpd_parse_idle_states(np, states, state_count);
> + if (ret)
> + return ret;
> +
> + /* Fill out the PSCI specifics for each found state. */
> + ret = psci_pd_parse_state_nodes(*states, *state_count);
> + if (ret)
> + kfree(*states);
> +
> + return ret;
> +}
> +
> +static int psci_pd_init(struct device_node *np)

__init ?

> +{
> + struct generic_pm_domain *pd;
> + struct psci_pd_provider *pd_provider;
> + struct dev_power_governor *pd_gov;
> + struct genpd_power_state *states = NULL;
> + int i, ret = -ENOMEM, state_count = 0;
> +
> + pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> + if (!pd)
> + goto out;
> +
> + pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
> + if (!pd_provider)
> + goto free_pd;
> +
> + pd->name = kasprintf(GFP_KERNEL, "%pOF", np);
> + if (!pd->name)
> + goto free_pd_prov;
> +
> + /*
> + * For OSI mode, parse the domain idle states and let genpd manage the
> + * state selection for those being compatible with "domain-idle-state".
> + */
> + if (psci_has_osi_support()) {
> + ret = psci_pd_parse_states(np, &states, &state_count);
> + if (ret)
> + goto free_name;
> + }
> +
> + pd->name = kbasename(pd->name);
> + pd->power_off = psci_pd_power_off;
> + pd->states = states;
> + pd->state_count = state_count;
> + pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
> +
> + /* 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_state;
> +
> + 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, &psci_pd_providers);
> +
> + pr_debug("init PM domain %s\n", pd->name);
> + return 0;
> +
> +remove_pd:
> + pm_genpd_remove(pd);
> +free_state:
> + for (i = 0; i < state_count; i++)
> + kfree(states[i].data);
> + kfree(states);
> +free_name:
> + kfree(pd->name);
> +free_pd_prov:
> + kfree(pd_provider);
> +free_pd:
> + kfree(pd);
> +out:
> + pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
> + return ret;
> +}
> +
> +static void psci_pd_remove(void)
> +{
> + struct psci_pd_provider *pd_provider, *it;
> + struct generic_pm_domain *genpd;
> + int i;
> +
> + list_for_each_entry_safe(pd_provider, it, &psci_pd_providers, link) {
> + of_genpd_del_provider(pd_provider->node);
> +
> + genpd = of_genpd_remove_last(pd_provider->node);
> + if (!IS_ERR(genpd)) {
> + for (i = 0; i < genpd->state_count; i++)
> + kfree(genpd->states[i].data);
> + kfree(genpd->states);
> + kfree(genpd);
> + }
> +
> + of_node_put(pd_provider->node);
> + list_del(&pd_provider->link);
> + kfree(pd_provider);
> + }
> +}
> +
> +static int psci_pd_init_topology(struct device_node *np)

__init ?

> +{
> + struct device_node *node;
> + struct of_phandle_args child, parent;
> + int ret;
> +
> + for_each_child_of_node(np, node) {
> + if (of_parse_phandle_with_args(node, "power-domains",
> + "#power-domain-cells", 0, &parent))
> + continue;
> +
> + child.np = node;
> + child.args_count = 0;
> +
> + ret = of_genpd_add_subdomain(&parent, &child);
> + of_node_put(parent.np);
> + if (ret) {
> + of_node_put(node);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +int psci_dt_init_pm_domains(struct device_node *np)

__init ?

> +{
> + struct device_node *node;
> + int ret, pd_count = 0;
> +
> + /*
> + * 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 = psci_pd_init(node);
> + if (ret)
> + goto put_node;
> +
> + pd_count++;
> + }
> +
> + /* Bail out if not using the hierarchical CPU topology. */
> + if (!pd_count)
> + return 0;
> +
> + /* Link genpd masters/subdomains to model the CPU topology. */
> + ret = psci_pd_init_topology(np);
> + if (ret)
> + goto remove_pd;
> +
> + /* Try to enable OSI mode if supported. */
> + if (psci_has_osi_support())
> + osi_mode_enabled = psci_set_osi_mode();
> +
> + pr_info("Initialized CPU PM domain topology\n");
> + return pd_count;
> +
> +put_node:
> + of_node_put(node);
> +remove_pd:
> + if (pd_count)
> + psci_pd_remove();
> + pr_err("failed to create CPU PM domains ret=%d\n", ret);
> + return ret;
> +}
> +#endif
>


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