[PATCH v2 10/11] firmware: arm_scmi: Add the SCMI performance domain

Ulf Hansson
2023-07-13T14:19:31Z

To enable support for performance scaling (DVFS) for generic devices with
the SCMI performance protocol, let's add an SCMI performance domain. This
is being modelled as a genpd provider, with support for performance scaling
through genpd's ->set_performance_state() callback.

Note that, this adds the initial support that allows consumer drivers for
attached devices, to vote for a new performance state via calling the
dev_pm_genpd_set_performance_state(). However, this should be avoided as
it's in most cases preferred to use the OPP library to vote for a new OPP
instead. The support using the OPP library isn't part of this change, but
needs to be implemented from subsequent changes.

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

Changes in v2:
- Converted to use the new ->domain_info_get() callback.

---
drivers/firmware/arm_scmi/Kconfig | 12 ++
drivers/firmware/arm_scmi/Makefile | 1 +
drivers/firmware/arm_scmi/scmi_perf_domain.c | 155 +++++++++++++++++++
3 files changed, 168 insertions(+)
create mode 100644 drivers/firmware/arm_scmi/scmi_perf_domain.c

diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
index ea0f5083ac47..706d1264d038 100644
--- a/drivers/firmware/arm_scmi/Kconfig
+++ b/drivers/firmware/arm_scmi/Kconfig
@@ -181,6 +181,18 @@ config ARM_SCMI_POWER_DOMAIN
will be called scmi_pm_domain. Note this may needed early in boot
before rootfs may be available.

+config ARM_SCMI_PERF_DOMAIN
+ tristate "SCMI performance domain driver"
+ depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
+ default y
+ select PM_GENERIC_DOMAINS if PM
+ help
+ This enables support for the SCMI performance domains which can be
+ enabled or disabled via the SCP firmware.
+
+ This driver can also be built as a module. If so, the module will be
+ called scmi_perf_domain.
+
config ARM_SCMI_POWER_CONTROL
tristate "SCMI system power control driver"
depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
index b31d78fa66cc..afee66a65dcb 100644
--- a/drivers/firmware/arm_scmi/Makefile
+++ b/drivers/firmware/arm_scmi/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-core.o
obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-module.o

obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o
+obj-$(CONFIG_ARM_SCMI_PERF_DOMAIN) += scmi_perf_domain.o
obj-$(CONFIG_ARM_SCMI_POWER_CONTROL) += scmi_power_control.o

ifeq ($(CONFIG_THUMB2_KERNEL)$(CONFIG_CC_IS_CLANG),yy)
diff --git a/drivers/firmware/arm_scmi/scmi_perf_domain.c b/drivers/firmware/arm_scmi/scmi_perf_domain.c
new file mode 100644
index 000000000000..4ed2401995be
--- /dev/null
+++ b/drivers/firmware/arm_scmi/scmi_perf_domain.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCMI performance domain support.
+ *
+ * Copyright (C) 2023 Linaro Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pm_domain.h>
+#include <linux/scmi_protocol.h>
+#include <linux/slab.h>
+
+struct scmi_perf_domain {
+ struct generic_pm_domain genpd;
+ const struct scmi_perf_proto_ops *perf_ops;
+ const struct scmi_protocol_handle *ph;
+ const struct scmi_perf_domain_info *info;
+ u32 domain_id;
+};
+
+#define to_scmi_pd(pd) container_of(pd, struct scmi_perf_domain, genpd)
+
+static int
+scmi_pd_set_perf_state(struct generic_pm_domain *genpd, unsigned int state)
+{
+ struct scmi_perf_domain *pd = to_scmi_pd(genpd);
+ int ret;
+
+ if (!pd->info->set_perf)
+ return 0;
+
+ ret = pd->perf_ops->level_set(pd->ph, pd->domain_id, state, true);
+ if (ret)
+ dev_warn(&genpd->dev, "Failed with %d when trying to set %d perf level",
+ ret, state);
+
+ return ret;
+}
+
+static int scmi_perf_domain_probe(struct scmi_device *sdev)
+{
+ struct device *dev = &sdev->dev;
+ const struct scmi_handle *handle = sdev->handle;
+ const struct scmi_perf_proto_ops *perf_ops;
+ struct scmi_protocol_handle *ph;
+ struct scmi_perf_domain *scmi_pd;
+ struct genpd_onecell_data *scmi_pd_data;
+ struct generic_pm_domain **domains;
+ int num_domains, i, ret = 0;
+ u32 perf_level;
+
+ if (!handle)
+ return -ENODEV;
+
+ /* The OF node must specify us as a power-domain provider. */
+ if (!of_find_property(dev->of_node, "#power-domain-cells", NULL))
+ return 0;
+
+ perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
+ if (IS_ERR(perf_ops))
+ return PTR_ERR(perf_ops);
+
+ num_domains = perf_ops->num_domains_get(ph);
+ if (num_domains < 0) {
+ dev_warn(dev, "Failed with %d when getting num perf domains\n",
+ num_domains);
+ return num_domains;
+ } else if (!num_domains) {
+ return 0;
+ }
+
+ scmi_pd = devm_kcalloc(dev, num_domains, sizeof(*scmi_pd), GFP_KERNEL);
+ if (!scmi_pd)
+ return -ENOMEM;
+
+ scmi_pd_data = devm_kzalloc(dev, sizeof(*scmi_pd_data), GFP_KERNEL);
+ if (!scmi_pd_data)
+ return -ENOMEM;
+
+ domains = devm_kcalloc(dev, num_domains, sizeof(*domains), GFP_KERNEL);
+ if (!domains)
+ return -ENOMEM;
+
+ for (i = 0; i < num_domains; i++, scmi_pd++) {
+ scmi_pd->info = perf_ops->domain_info_get(ph, i);
+
+ scmi_pd->domain_id = i;
+ scmi_pd->perf_ops = perf_ops;
+ scmi_pd->ph = ph;
+ scmi_pd->genpd.name = scmi_pd->info->name;
+ scmi_pd->genpd.flags = GENPD_FLAG_OPP_TABLE_FW;
+ scmi_pd->genpd.set_performance_state = scmi_pd_set_perf_state;
+
+ ret = perf_ops->level_get(ph, i, &perf_level, false);
+ if (ret) {
+ dev_dbg(dev, "Failed to get perf level for %s",
+ scmi_pd->genpd.name);
+ perf_level = 0;
+ }
+
+ /* Let the perf level indicate the power-state too. */
+ ret = pm_genpd_init(&scmi_pd->genpd, NULL, perf_level == 0);
+ if (ret)
+ goto err;
+
+ domains[i] = &scmi_pd->genpd;
+ }
+
+ scmi_pd_data->domains = domains;
+ scmi_pd_data->num_domains = num_domains;
+
+ ret = of_genpd_add_provider_onecell(dev->of_node, scmi_pd_data);
+ if (ret)
+ goto err;
+
+ dev_set_drvdata(dev, scmi_pd_data);
+ dev_info(dev, "Initialized %d performance domains", num_domains);
+ return 0;
+err:
+ for (i--; i >= 0; i--)
+ pm_genpd_remove(domains[i]);
+ return ret;
+}
+
+static void scmi_perf_domain_remove(struct scmi_device *sdev)
+{
+ struct device *dev = &sdev->dev;
+ struct genpd_onecell_data *scmi_pd_data = dev_get_drvdata(dev);
+ int i;
+
+ of_genpd_del_provider(dev->of_node);
+
+ for (i = 0; i < scmi_pd_data->num_domains; i++)
+ pm_genpd_remove(scmi_pd_data->domains[i]);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+ { SCMI_PROTOCOL_PERF, "perf" },
+ { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_perf_domain_driver = {
+ .name = "scmi-perf-domain",
+ .probe = scmi_perf_domain_probe,
+ .remove = scmi_perf_domain_remove,
+ .id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_perf_domain_driver);
+
+MODULE_AUTHOR("Ulf Hansson <ulf.hansson@linaro.org>");
+MODULE_DESCRIPTION("ARM SCMI perf domain driver");
+MODULE_LICENSE("GPL v2");
--
2.34.1