scsi: ufs: core: Add OPP support for scaling clocks and regulators

UFS core is only scaling the clocks during devfreq scaling and
initialization. But for an optimum power saving, regulators should also be
scaled along with the clocks.

So let's use the OPP framework which supports scaling clocks, regulators,
and performance state using OPP table defined in devicetree. For
accomodating the OPP support, the existing APIs (ufshcd_scale_clks,
ufshcd_is_devfreq_scaling_required and ufshcd_devfreq_scale) are modified
to accept "freq" as an argument which in turn used by the OPP helpers.

The OPP support is added along with the old freq-table based clock scaling
so that the existing platforms work as expected.

Co-developed-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Manivannan Sadhasivam <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/ufs/core/ufshcd.c

···
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/pm_opp.h>
 #include <linux/regulator/consumer.h>
 #include <linux/sched/clock.h>
 #include <linux/iopoll.h>
···
 static int ufshcd_host_reset_and_restore(struct ufs_hba *hba);
 static void ufshcd_resume_clkscaling(struct ufs_hba *hba);
 static void ufshcd_suspend_clkscaling(struct ufs_hba *hba);
-static int ufshcd_scale_clks(struct ufs_hba *hba, bool scale_up);
+static int ufshcd_scale_clks(struct ufs_hba *hba, unsigned long freq,
+			     bool scale_up);
 static irqreturn_t ufshcd_intr(int irq, void *__hba);
 static int ufshcd_change_power_mode(struct ufs_hba *hba,
 			     struct ufs_pa_layer_attr *pwr_mode);
···
 	return ret;
 }
 
+static int ufshcd_opp_set_rate(struct ufs_hba *hba, unsigned long freq)
+{
+	struct dev_pm_opp *opp;
+	int ret;
+
+	opp = dev_pm_opp_find_freq_floor_indexed(hba->dev,
+						 &freq, 0);
+	if (IS_ERR(opp))
+		return PTR_ERR(opp);
+
+	ret = dev_pm_opp_set_opp(hba->dev, opp);
+	dev_pm_opp_put(opp);
+
+	return ret;
+}
+
 /**
  * ufshcd_scale_clks - scale up or scale down UFS controller clocks
  * @hba: per adapter instance
+ * @freq: frequency to scale
  * @scale_up: True if scaling up and false if scaling down
  *
  * Return: 0 if successful; < 0 upon failure.
  */
-static int ufshcd_scale_clks(struct ufs_hba *hba, bool scale_up)
+static int ufshcd_scale_clks(struct ufs_hba *hba, unsigned long freq,
+			     bool scale_up)
 {
 	int ret = 0;
 	ktime_t start = ktime_get();
···
 	if (ret)
 		goto out;
 
-	ret = ufshcd_set_clk_freq(hba, scale_up);
+	if (hba->use_pm_opp)
+		ret = ufshcd_opp_set_rate(hba, freq);
+	else
+		ret = ufshcd_set_clk_freq(hba, scale_up);
 	if (ret)
 		goto out;
 
 	ret = ufshcd_vops_clk_scale_notify(hba, scale_up, POST_CHANGE);
-	if (ret)
-		ufshcd_set_clk_freq(hba, !scale_up);
+	if (ret) {
+		if (hba->use_pm_opp)
+			ufshcd_opp_set_rate(hba,
+					    hba->devfreq->previous_freq);
+		else
+			ufshcd_set_clk_freq(hba, !scale_up);
+	}
 
 out:
 	trace_ufshcd_profile_clk_scaling(dev_name(hba->dev),
···
 /**
  * ufshcd_is_devfreq_scaling_required - check if scaling is required or not
  * @hba: per adapter instance
+ * @freq: frequency to scale
  * @scale_up: True if scaling up and false if scaling down
  *
  * Return: true if scaling is required, false otherwise.
  */
 static bool ufshcd_is_devfreq_scaling_required(struct ufs_hba *hba,
-					       bool scale_up)
+					       unsigned long freq, bool scale_up)
 {
 	struct ufs_clk_info *clki;
 	struct list_head *head = &hba->clk_list_head;
 
 	if (list_empty(head))
 		return false;
+
+	if (hba->use_pm_opp)
+		return freq != hba->clk_scaling.target_freq;
 
 	list_for_each_entry(clki, head, list) {
 		if (!IS_ERR_OR_NULL(clki->clk)) {
···
 /**
  * ufshcd_devfreq_scale - scale up/down UFS clocks and gear
  * @hba: per adapter instance
+ * @freq: frequency to scale
  * @scale_up: True for scaling up and false for scalin down
  *
  * Return: 0 for success; -EBUSY if scaling can't happen at this time; non-zero
  * for any other errors.
  */
-static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
+static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
+				bool scale_up)
 {
 	int ret = 0;
 
···
 			goto out_unprepare;
 	}
 
-	ret = ufshcd_scale_clks(hba, scale_up);
+	ret = ufshcd_scale_clks(hba, freq, scale_up);
 	if (ret) {
 		if (!scale_up)
 			ufshcd_scale_gear(hba, true);
···
 	if (scale_up) {
 		ret = ufshcd_scale_gear(hba, true);
 		if (ret) {
-			ufshcd_scale_clks(hba, false);
+			ufshcd_scale_clks(hba, hba->devfreq->previous_freq,
+					  false);
 			goto out_unprepare;
 		}
 	}
···
 	if (!ufshcd_is_clkscaling_supported(hba))
 		return -EINVAL;
 
-	clki = list_first_entry(&hba->clk_list_head, struct ufs_clk_info, list);
-	/* Override with the closest supported frequency */
-	*freq = (unsigned long) clk_round_rate(clki->clk, *freq);
+	if (hba->use_pm_opp) {
+		struct dev_pm_opp *opp;
+
+		/* Get the recommended frequency from OPP framework */
+		opp = devfreq_recommended_opp(dev, freq, flags);
+		if (IS_ERR(opp))
+			return PTR_ERR(opp);
+
+		dev_pm_opp_put(opp);
+	} else {
+		/* Override with the closest supported frequency */
+		clki = list_first_entry(&hba->clk_list_head, struct ufs_clk_info,
+					list);
+		*freq =	(unsigned long) clk_round_rate(clki->clk, *freq);
+	}
+
 	spin_lock_irqsave(hba->host->host_lock, irq_flags);
 	if (ufshcd_eh_in_progress(hba)) {
 		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
···
 		goto out;
 	}
 
-	/* Decide based on the rounded-off frequency and update */
-	scale_up = *freq == clki->max_freq;
-	if (!scale_up)
+	/* Decide based on the target or rounded-off frequency and update */
+	if (hba->use_pm_opp)
+		scale_up = *freq > hba->clk_scaling.target_freq;
+	else
+		scale_up = *freq == clki->max_freq;
+
+	if (!hba->use_pm_opp && !scale_up)
 		*freq = clki->min_freq;
+
 	/* Update the frequency */
-	if (!ufshcd_is_devfreq_scaling_required(hba, scale_up)) {
+	if (!ufshcd_is_devfreq_scaling_required(hba, *freq, scale_up)) {
 		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
 		ret = 0;
 		goto out; /* no state change required */
···
 	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
 
 	start = ktime_get();
-	ret = ufshcd_devfreq_scale(hba, scale_up);
+	ret = ufshcd_devfreq_scale(hba, *freq, scale_up);
+	if (!ret)
+		hba->clk_scaling.target_freq = *freq;
 
 	trace_ufshcd_profile_clk_scaling(dev_name(hba->dev),
 		(scale_up ? "up" : "down"),
···
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 	struct ufs_clk_scaling *scaling = &hba->clk_scaling;
 	unsigned long flags;
-	struct list_head *clk_list = &hba->clk_list_head;
-	struct ufs_clk_info *clki;
 	ktime_t curr_t;
 
 	if (!ufshcd_is_clkscaling_supported(hba))
···
 	if (!scaling->window_start_t)
 		goto start_window;
 
-	clki = list_first_entry(clk_list, struct ufs_clk_info, list);
 	/*
 	 * If current frequency is 0, then the ondemand governor considers
 	 * there's no initial frequency set. And it always requests to set
 	 * to max. frequency.
 	 */
-	stat->current_frequency = clki->curr_freq;
+	if (hba->use_pm_opp) {
+		stat->current_frequency = hba->clk_scaling.target_freq;
+	} else {
+		struct list_head *clk_list = &hba->clk_list_head;
+		struct ufs_clk_info *clki;
+
+		clki = list_first_entry(clk_list, struct ufs_clk_info, list);
+		stat->current_frequency = clki->curr_freq;
+	}
+
 	if (scaling->is_busy_started)
 		scaling->tot_busy_t += ktime_us_delta(curr_t,
 				scaling->busy_start_t);
-
 	stat->total_time = ktime_us_delta(curr_t, scaling->window_start_t);
 	stat->busy_time = scaling->tot_busy_t;
 start_window:
···
 	if (list_empty(clk_list))
 		return 0;
 
-	clki = list_first_entry(clk_list, struct ufs_clk_info, list);
-	dev_pm_opp_add(hba->dev, clki->min_freq, 0);
-	dev_pm_opp_add(hba->dev, clki->max_freq, 0);
+	if (!hba->use_pm_opp) {
+		clki = list_first_entry(clk_list, struct ufs_clk_info, list);
+		dev_pm_opp_add(hba->dev, clki->min_freq, 0);
+		dev_pm_opp_add(hba->dev, clki->max_freq, 0);
+	}
 
 	ufshcd_vops_config_scaling_param(hba, &hba->vps->devfreq_profile,
 					 &hba->vps->ondemand_data);
···
 		ret = PTR_ERR(devfreq);
 		dev_err(hba->dev, "Unable to register with devfreq %d\n", ret);
 
-		dev_pm_opp_remove(hba->dev, clki->min_freq);
-		dev_pm_opp_remove(hba->dev, clki->max_freq);
+		if (!hba->use_pm_opp) {
+			dev_pm_opp_remove(hba->dev, clki->min_freq);
+			dev_pm_opp_remove(hba->dev, clki->max_freq);
+		}
 		return ret;
 	}
 
···
 static void ufshcd_devfreq_remove(struct ufs_hba *hba)
 {
 	struct list_head *clk_list = &hba->clk_list_head;
-	struct ufs_clk_info *clki;
 
 	if (!hba->devfreq)
 		return;
···
 	devfreq_remove_device(hba->devfreq);
 	hba->devfreq = NULL;
 
-	clki = list_first_entry(clk_list, struct ufs_clk_info, list);
-	dev_pm_opp_remove(hba->dev, clki->min_freq);
-	dev_pm_opp_remove(hba->dev, clki->max_freq);
+	if (!hba->use_pm_opp) {
+		struct ufs_clk_info *clki;
+
+		clki = list_first_entry(clk_list, struct ufs_clk_info, list);
+		dev_pm_opp_remove(hba->dev, clki->min_freq);
+		dev_pm_opp_remove(hba->dev, clki->max_freq);
+	}
 }
 
 static void ufshcd_suspend_clkscaling(struct ufs_hba *hba)
···
 		ufshcd_resume_clkscaling(hba);
 	} else {
 		ufshcd_suspend_clkscaling(hba);
-		err = ufshcd_devfreq_scale(hba, true);
+		err = ufshcd_devfreq_scale(hba, ULONG_MAX, true);
 		if (err)
 			dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
 					__func__, err);
···
 	hba->silence_err_logs = false;
 
 	/* scale up clocks to max frequency before full reinitialization */
-	ufshcd_scale_clks(hba, true);
+	ufshcd_scale_clks(hba, ULONG_MAX, true);
 
 	err = ufshcd_hba_enable(hba);
 
···
 		dev_dbg(dev, "%s: clk: %s, rate: %lu\n", __func__,
 				clki->name, clk_get_rate(clki->clk));
 	}
+
+	/* Set Max. frequency for all clocks */
+	if (hba->use_pm_opp) {
+		ret = ufshcd_opp_set_rate(hba, ULONG_MAX);
+		if (ret) {
+			dev_err(hba->dev, "%s: failed to set OPP: %d", __func__,
+				ret);
+			goto out;
+		}
+	}
+
 out:
 	return ret;
 }

include/ufs/ufshcd.h

···
  * @workq: workqueue to schedule devfreq suspend/resume work
  * @suspend_work: worker to suspend devfreq
  * @resume_work: worker to resume devfreq
+ * @target_freq: frequency requested by devfreq framework
  * @min_gear: lowest HS gear to scale down to
  * @is_enabled: tracks if scaling is currently enabled or not, controlled by
  *		clkscale_enable sysfs node
···
 	struct workqueue_struct *workq;
 	struct work_struct suspend_work;
 	struct work_struct resume_work;
+	unsigned long target_freq;
 	u32 min_gear;
 	bool is_enabled;
 	bool is_allowed;
···
  * @auto_bkops_enabled: to track whether bkops is enabled in device
  * @vreg_info: UFS device voltage regulator information
  * @clk_list_head: UFS host controller clocks list node head
+ * @use_pm_opp: Indicates whether OPP based scaling is used or not
  * @req_abort_count: number of times ufshcd_abort() has been called
  * @lanes_per_direction: number of lanes per data direction between the UFS
  *	controller and the UFS device.
···
 	bool auto_bkops_enabled;
 	struct ufs_vreg_info vreg_info;
 	struct list_head clk_list_head;
+	bool use_pm_opp;
 
 	/* Number of requests aborts */
 	int req_abort_count;