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 <krzysztof.kozlowski@linaro.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20231012172129.65172-3-manivannan.sadhasivam@linaro.orgSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>

include/ufs/ufshcd.h

@@ -429,6 +429,7 @@ struct ufs_clk_gating {
  * @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
@@ -448,6 +449,7 @@ struct ufs_clk_scaling {
 	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;
@@ -862,6 +864,7 @@ enum ufshcd_mcq_opr {
  * @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.
@@ -1012,6 +1015,7 @@ struct ufs_hba {
 	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;