drm/panthor: record current and maximum device clock frequencies

In order to support UM in calculating rates of GPU utilisation, the current
operating and maximum GPU clock frequencies must be recorded during device
initialisation, and also during OPP state transitions.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240923230912.2207320-3-adrian.larumbe@collabora.com

drivers/gpu/drm/panthor/panthor_devfreq.c

@@ -62,14 +62,20 @@ static void panthor_devfreq_update_utilization(struct panthor_devfreq *pdevfreq)
 static int panthor_devfreq_target(struct device *dev, unsigned long *freq,
 				  u32 flags)
 {
+	struct panthor_device *ptdev = dev_get_drvdata(dev);
 	struct dev_pm_opp *opp;
+	int err;
 
 	opp = devfreq_recommended_opp(dev, freq, flags);
 	if (IS_ERR(opp))
 		return PTR_ERR(opp);
 	dev_pm_opp_put(opp);
 
-	return dev_pm_opp_set_rate(dev, *freq);
+	err = dev_pm_opp_set_rate(dev, *freq);
+	if (!err)
+		ptdev->current_frequency = *freq;
+
+	return err;
 }
 
 static void panthor_devfreq_reset(struct panthor_devfreq *pdevfreq)
@@ -130,6 +136,7 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
 	struct panthor_devfreq *pdevfreq;
 	struct dev_pm_opp *opp;
 	unsigned long cur_freq;
+	unsigned long freq = ULONG_MAX;
 	int ret;
 
 	pdevfreq = drmm_kzalloc(&ptdev->base, sizeof(*ptdev->devfreq), GFP_KERNEL);
@@ -161,6 +168,7 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
 		return PTR_ERR(opp);
 
 	panthor_devfreq_profile.initial_freq = cur_freq;
+	ptdev->current_frequency = cur_freq;
 
 	/* Regulator coupling only takes care of synchronizing/balancing voltage
 	 * updates, but the coupled regulator needs to be enabled manually.
@@ -204,6 +212,14 @@ int panthor_devfreq_init(struct panthor_device *ptdev)
 
 	dev_pm_opp_put(opp);
 
+	/* Find the fastest defined rate  */
+	opp = dev_pm_opp_find_freq_floor(dev, &freq);
+	if (IS_ERR(opp))
+		return PTR_ERR(opp);
+	ptdev->fast_rate = freq;
+
+	dev_pm_opp_put(opp);
+
 	/*
 	 * Setup default thresholds for the simple_ondemand governor.
 	 * The values are chosen based on experiments.

drivers/gpu/drm/panthor/panthor_device.h

@@ -184,6 +184,12 @@ struct panthor_device {
 
 	/** @profile_mask: User-set profiling flags for job accounting. */
 	u32 profile_mask;
+
+	/** @current_frequency: Device clock frequency at present. Set by DVFS*/
+	unsigned long current_frequency;
+
+	/** @fast_rate: Maximum device clock frequency. Set by DVFS */
+	unsigned long fast_rate;
 };
 
 /**