[PATCH 16/16] firmware: arm_scmi: Add generic OPP support to the SCMI performance domain

[Ulf Hansson <ulf.hansson@linaro.org>]

To allow a consumer driver to use the generic OPP library to scale the
performance for its device, let's dynamically add the OPP table when the
device gets attached to the SCMI performance domain.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/firmware/arm_scmi/scmi_perf_domain.c | 34 ++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/firmware/arm_scmi/scmi_perf_domain.c b/drivers/firmware/arm_scmi/scmi_perf_domain.c
index 9be90a7d94de..e9767ca1d34f 100644
--- a/drivers/firmware/arm_scmi/scmi_perf_domain.c
+++ b/drivers/firmware/arm_scmi/scmi_perf_domain.c
@@ -9,6 +9,7 @@
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_opp.h>
 #include <linux/scmi_protocol.h>
 #include <linux/slab.h>
 
@@ -39,6 +40,37 @@ scmi_pd_set_perf_state(struct generic_pm_domain *genpd, unsigned int state)
 	return ret;
 }
 
+static int
+scmi_pd_attach_dev(struct generic_pm_domain *genpd, struct device *dev)
+{
+	struct scmi_perf_domain *pd = to_scmi_pd(genpd);
+	int ret;
+
+	/*
+	 * Allow the device to be attached, but don't add the OPP table unless
+	 * the performance level can be changed.
+	 */
+	if (!pd->can_level_set)
+		return 0;
+
+	ret = pd->perf_ops->device_opps_add(pd->ph, dev, pd->domain_id, true);
+	if (ret)
+		dev_warn(dev, "failed to add OPPs for the device\n");
+
+	return ret;
+}
+
+static void
+scmi_pd_detach_dev(struct generic_pm_domain *genpd, struct device *dev)
+{
+	struct scmi_perf_domain *pd = to_scmi_pd(genpd);
+
+	if (!pd->can_level_set)
+		return;
+
+	dev_pm_opp_remove_all_dynamic(dev);
+}
+
 static int scmi_perf_domain_probe(struct scmi_device *sdev)
 {
 	struct device *dev = &sdev->dev;
@@ -92,6 +124,8 @@ static int scmi_perf_domain_probe(struct scmi_device *sdev)
 		scmi_pd->genpd.name = perf_ops->name_get(ph, i);
 		scmi_pd->genpd.flags = GENPD_FLAG_OPP_TABLE_FW;
 		scmi_pd->genpd.set_performance_state = scmi_pd_set_perf_state;
+		scmi_pd->genpd.attach_dev = scmi_pd_attach_dev;
+		scmi_pd->genpd.detach_dev = scmi_pd_detach_dev;
 
 		ret = perf_ops->level_get(ph, i, &perf_level, false);
 		if (ret) {
-- 
2.34.1