[v6,20/25] drivers: firmware: psci: Introduce psci_dt_topology_init()

Message ID 1521046715-30683-21-git-send-email-ulf.hansson@linaro.org
State New
Headers show
Series
  • PM / Domains: Support hierarchical CPU arrangement (PSCI/ARM)
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Commit Message

Ulf Hansson March 14, 2018, 4:58 p.m.
In case the hierarchical layout is used in DT, we want to initialize the
corresponding PM domain topology for the CPUs, by using the generic PM
domain (aka genpd) infrastructure.

At first glance, it may seem feasible to hook into the existing
psci_dt_init() function, although because it's called quite early in the
boot sequence, allocating the dynamic data structure for a genpd doesn't
work.

Therefore, let's export a new init function for PSCI,
psci_dt_topology_init(), which the ARM machine code should call from a
suitable initcall.

Succeeding to initialize the PM domain topology, which means at least one
instance of a genpd becomes created, allows us to continue to enable the
PSCI OS initiated mode for the platform. If everything turns out fine,
let's print a message in log to inform the user about the changed mode.

In case of any failures, we stick to the default PSCI Platform Coordinated
mode.

Cc: Lina Iyer <ilina@codeaurora.org>
Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

---
 drivers/firmware/psci.c | 31 +++++++++++++++++++++++++++++++
 include/linux/psci.h    |  2 ++
 2 files changed, 33 insertions(+)

-- 
2.7.4

Comments

Ulf Hansson April 10, 2018, 7:19 a.m. | #1
On 14 March 2018 at 18:38, Mark Rutland <mark.rutland@arm.com> wrote:
> On Wed, Mar 14, 2018 at 05:58:30PM +0100, Ulf Hansson wrote:

>> In case the hierarchical layout is used in DT, we want to initialize the

>> corresponding PM domain topology for the CPUs, by using the generic PM

>> domain (aka genpd) infrastructure.

>>

>> At first glance, it may seem feasible to hook into the existing

>> psci_dt_init() function, although because it's called quite early in the

>> boot sequence, allocating the dynamic data structure for a genpd doesn't

>> work.

>>

>> Therefore, let's export a new init function for PSCI,

>> psci_dt_topology_init(), which the ARM machine code should call from a

>> suitable initcall.

>>

>> Succeeding to initialize the PM domain topology, which means at least one

>> instance of a genpd becomes created, allows us to continue to enable the

>> PSCI OS initiated mode for the platform. If everything turns out fine,

>> let's print a message in log to inform the user about the changed mode.

>>

>> In case of any failures, we stick to the default PSCI Platform Coordinated

>> mode.

>

> For kexec/kdump we'll need to explicitly set the suspend mode to

> platform coordinated if for whatever reason we choose not to use OSI.


Could you please elaborate on this? I am not really understanding what
you are suggesting me to do and why.

>

>>

>> Cc: Lina Iyer <ilina@codeaurora.org>

>> Co-developed-by: Lina Iyer <lina.iyer@linaro.org>

>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

>> ---

>>  drivers/firmware/psci.c | 31 +++++++++++++++++++++++++++++++

>>  include/linux/psci.h    |  2 ++

>>  2 files changed, 33 insertions(+)

>>

>> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c

>> index 463f78c..45d55fc 100644

>> --- a/drivers/firmware/psci.c

>> +++ b/drivers/firmware/psci.c

>> @@ -723,6 +723,37 @@ int __init psci_dt_init(void)

>>       return ret;

>>  }

>>

>> +int __init psci_dt_topology_init(void)

>> +{

>> +     struct device_node *np;

>> +     int ret;

>> +

>> +     if (!psci_has_osi_support())

>> +             return 0;

>> +

>> +     np = of_find_matching_node_and_match(NULL, psci_of_match, NULL);

>> +     if (!np)

>> +             return -ENODEV;

>> +

>> +     /* Initialize the CPU PM domains based on topology described in DT. */

>> +     ret = psci_dt_init_pm_domains(np);

>> +     if (ret <= 0)

>> +             goto out;

>> +

>> +     /* Enable OSI mode. */

>> +     ret = invoke_psci_fn(PSCI_1_0_FN_SET_SUSPEND_MODE,

>> +                          PSCI_1_0_SUSPEND_MODE_OSI, 0, 0);

>

> IIUC, this patch will need to be moved after the subsequent two patches

> to ensure that this series bisects cleanly.


Actually not.

$subject patch adds a new init function, which purpose is to
initialize the PSCI PM domains. At this point none is calling it.

The following changes, builds on top, making it possible to add CPU
devices to the PSCI PM domains (if the PM domains has been created and
OSI mode successfully enabled) and also to properly deal CPU hotplug
when OSI mode is enabled.

The purpose doing it this way is to keep changes small and
review-able, but in principle I can squash 20, 21 and 22 - if you
prefer.

Again, thanks for reviewing!

Kind regards
Uffe

Patch

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 463f78c..45d55fc 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -723,6 +723,37 @@  int __init psci_dt_init(void)
 	return ret;
 }
 
+int __init psci_dt_topology_init(void)
+{
+	struct device_node *np;
+	int ret;
+
+	if (!psci_has_osi_support())
+		return 0;
+
+	np = of_find_matching_node_and_match(NULL, psci_of_match, NULL);
+	if (!np)
+		return -ENODEV;
+
+	/* Initialize the CPU PM domains based on topology described in DT. */
+	ret = psci_dt_init_pm_domains(np);
+	if (ret <= 0)
+		goto out;
+
+	/* Enable OSI mode. */
+	ret = invoke_psci_fn(PSCI_1_0_FN_SET_SUSPEND_MODE,
+			     PSCI_1_0_SUSPEND_MODE_OSI, 0, 0);
+	if (ret) {
+		pr_info("failed to enable OSI mode: %d\n", ret);
+		goto out;
+	}
+
+	pr_info("OSI mode enabled.\n");
+out:
+	of_node_put(np);
+	return ret;
+}
+
 #ifdef CONFIG_ACPI
 /*
  * We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 8b1b3b5..298a044 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -53,8 +53,10 @@  extern struct psci_operations psci_ops;
 
 #if defined(CONFIG_ARM_PSCI_FW)
 int __init psci_dt_init(void);
+int __init psci_dt_topology_init(void);
 #else
 static inline int psci_dt_init(void) { return 0; }
+static inline int psci_dt_topology_init(void) { return 0; }
 #endif
 
 #if defined(CONFIG_ARM_PSCI_FW) && defined(CONFIG_ACPI)