scsi: ufs: core: Add support for parsing OPP

OPP framework can be used to scale the clocks along with other entities
such as regulators, performance state etc... So let's add support for
parsing OPP from devicetree. OPP support in devicetree is added through the
"operating-points-v2" property which accepts the OPP table defining clock
frequency, regulator voltage, power domain performance state etc...

Since the UFS controller requires multiple clocks to be controlled for
proper working, devm_pm_opp_set_config() has been used which supports
scaling multiple clocks through custom ufshcd_opp_config_clks() callback.

It should be noted that the OPP support is not compatible with the old
"freq-table-hz" property. So only one can be used at a time even though
the UFS core supports both.

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

···
 	return ret;
 }
 
+int ufshcd_opp_config_clks(struct device *dev, struct opp_table *opp_table,
+			   struct dev_pm_opp *opp, void *data,
+			   bool scaling_down)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+	struct list_head *head = &hba->clk_list_head;
+	struct ufs_clk_info *clki;
+	unsigned long freq;
+	u8 idx = 0;
+	int ret;
+
+	list_for_each_entry(clki, head, list) {
+		if (!IS_ERR_OR_NULL(clki->clk)) {
+			freq = dev_pm_opp_get_freq_indexed(opp, idx++);
+
+			/* Do not set rate for clocks having frequency as 0 */
+			if (!freq)
+				continue;
+
+			ret = clk_set_rate(clki->clk, freq);
+			if (ret) {
+				dev_err(dev, "%s: %s clk set rate(%ldHz) failed, %d\n",
+					__func__, clki->name, freq, ret);
+				return ret;
+			}
+
+			trace_ufshcd_clk_scaling(dev_name(dev),
+				(scaling_down ? "scaled down" : "scaled up"),
+				clki->name, hba->clk_scaling.target_freq, freq);
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ufshcd_opp_config_clks);
+
 static int ufshcd_opp_set_rate(struct ufs_hba *hba, unsigned long freq)
 {
 	struct dev_pm_opp *opp;

drivers/ufs/host/ufshcd-pltfrm.c

···
 
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
 
···
 	}
 }
 
+static int ufshcd_parse_operating_points(struct ufs_hba *hba)
+{
+	struct device *dev = hba->dev;
+	struct device_node *np = dev->of_node;
+	struct dev_pm_opp_config config = {};
+	struct ufs_clk_info *clki;
+	const char **clk_names;
+	int cnt, i, ret;
+
+	if (!of_find_property(np, "operating-points-v2", NULL))
+		return 0;
+
+	if (of_find_property(np, "freq-table-hz", NULL)) {
+		dev_err(dev, "%s: operating-points and freq-table-hz are incompatible\n",
+			 __func__);
+		return -EINVAL;
+	}
+
+	cnt = of_property_count_strings(np, "clock-names");
+	if (cnt <= 0) {
+		dev_err(dev, "%s: Missing clock-names\n",  __func__);
+		return -ENODEV;
+	}
+
+	/* OPP expects clk_names to be NULL terminated */
+	clk_names = devm_kcalloc(dev, cnt + 1, sizeof(*clk_names), GFP_KERNEL);
+	if (!clk_names)
+		return -ENOMEM;
+
+	/*
+	 * We still need to get reference to all clocks as the UFS core uses
+	 * them separately.
+	 */
+	for (i = 0; i < cnt; i++) {
+		ret = of_property_read_string_index(np, "clock-names", i,
+						    &clk_names[i]);
+		if (ret)
+			return ret;
+
+		clki = devm_kzalloc(dev, sizeof(*clki), GFP_KERNEL);
+		if (!clki)
+			return -ENOMEM;
+
+		clki->name = devm_kstrdup(dev, clk_names[i], GFP_KERNEL);
+		if (!clki->name)
+			return -ENOMEM;
+
+		if (!strcmp(clk_names[i], "ref_clk"))
+			clki->keep_link_active = true;
+
+		list_add_tail(&clki->list, &hba->clk_list_head);
+	}
+
+	config.clk_names = clk_names,
+	config.config_clks = ufshcd_opp_config_clks;
+
+	ret = devm_pm_opp_set_config(dev, &config);
+	if (ret)
+		return ret;
+
+	ret = devm_pm_opp_of_add_table(dev);
+	if (ret) {
+		dev_err(dev, "Failed to add OPP table: %d\n", ret);
+		return ret;
+	}
+
+	hba->use_pm_opp = true;
+
+	return 0;
+}
+
 /**
  * ufshcd_get_pwr_dev_param - get finally agreed attributes for
  *                            power mode change
···
 	}
 
 	ufshcd_init_lanes_per_dir(hba);
+
+	err = ufshcd_parse_operating_points(hba);
+	if (err) {
+		dev_err(dev, "%s: OPP parse failed %d\n", __func__, err);
+		goto dealloc_host;
+	}
 
 	err = ufshcd_init(hba, mmio_base, irq);
 	if (err) {

include/ufs/ufshcd.h

···
 void ufshcd_mcq_enable_esi(struct ufs_hba *hba);
 void ufshcd_mcq_config_esi(struct ufs_hba *hba, struct msi_msg *msg);
 
+int ufshcd_opp_config_clks(struct device *dev, struct opp_table *opp_table,
+			   struct dev_pm_opp *opp, void *data,
+			   bool scaling_down);
 /**
  * ufshcd_set_variant - set variant specific data to the hba
  * @hba: per adapter instance