[PATCH v12 1/6] soc: qcom: ice: Add OPP-based clock scaling support for ICE

[Abhinaba Rakshit <abhinaba.rakshit@oss.qualcomm.com>]

Register optional operation-points-v2 table for ICE device
during device probe. Attach the OPP-table with only the ICE
core clock. Since, dtbinding is on a transition phase to include
iface clock and clock-names, attaching the opp-table to core clock
remains optional such that it does not cause probe failures.

Introduce clock scaling API qcom_ice_scale_clk which scale ICE
core clock based on the target frequency provided and if a valid
OPP-table is registered. Use round_ceil passed to decide on the
rounding of the clock freq against OPP-table. Clock scaling is
disabled when a valid OPP-table is not registered.

This ensures when an ICE-device specific OPP table is available,
use the PM OPP framework to manage frequency scaling and maintain
proper power-domain constraints.

Reviewed-by: Harshal Dev <harshal.dev@oss.qualcomm.com>
Signed-off-by: Abhinaba Rakshit <abhinaba.rakshit@oss.qualcomm.com>
---
 drivers/soc/qcom/ice.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++
 include/soc/qcom/ice.h |  2 ++
 2 files changed, 77 insertions(+)

diff --git a/drivers/soc/qcom/ice.c b/drivers/soc/qcom/ice.c
index 5f20108aa03ebe9a47a10fba9afde420add0f34a..a7112b4ebab0c76ccb3faf9415dc22b28b73bdcc 100644
--- a/drivers/soc/qcom/ice.c
+++ b/drivers/soc/qcom/ice.c
@@ -17,6 +17,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/xarray.h>
+#include <linux/pm_opp.h>
 
 #include <linux/firmware/qcom/qcom_scm.h>
 
@@ -113,6 +114,7 @@ struct qcom_ice {
 	bool use_hwkm;
 	bool hwkm_init_complete;
 	u8 hwkm_version;
+	bool has_opp;
 };
 
 static DEFINE_XARRAY(ice_handles);
@@ -560,6 +562,50 @@ int qcom_ice_import_key(struct qcom_ice *ice,
 }
 EXPORT_SYMBOL_GPL(qcom_ice_import_key);
 
+/**
+ * qcom_ice_scale_clk() - Scale ICE clock for DVFS-aware operations
+ * @ice: ICE driver data
+ * @target_freq: requested frequency in Hz
+ * @round_ceil: when true, selects nearest freq >= @target_freq;
+ *              otherwise, selects nearest freq <= @target_freq
+ *
+ * Selects an OPP frequency based on @target_freq and the rounding direction
+ * specified by @round_ceil, then programs it using dev_pm_opp_set_rate(),
+ * including any voltage or power-domain transitions handled by the OPP
+ * framework.
+ *
+ * Return: 0 on success; -EOPNOTSUPP if no OPP table; or errno from
+ *         dev_pm_opp_set_rate()/OPP lookup.
+ */
+int qcom_ice_scale_clk(struct qcom_ice *ice, unsigned long target_freq,
+		       bool round_ceil)
+{
+	unsigned long ice_freq = target_freq;
+	struct dev_pm_opp *opp;
+	int ret;
+
+	if (!ice->has_opp)
+		return -EOPNOTSUPP;
+
+	if (round_ceil)
+		opp = dev_pm_opp_find_freq_ceil(ice->dev, &ice_freq);
+	else
+		opp = dev_pm_opp_find_freq_floor(ice->dev, &ice_freq);
+
+	if (IS_ERR(opp))
+		return PTR_ERR(opp);
+	dev_pm_opp_put(opp);
+
+	ret = dev_pm_opp_set_rate(ice->dev, ice_freq);
+	if (ret) {
+		dev_err(ice->dev, "Unable to scale ICE clock rate\n");
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(qcom_ice_scale_clk);
+
 static struct qcom_ice *qcom_ice_create(struct device *dev,
 					void __iomem *base)
 {
@@ -738,6 +784,7 @@ static int qcom_ice_probe(struct platform_device *pdev)
 	unsigned long phandle = pdev->dev.of_node->phandle;
 	struct qcom_ice *engine;
 	void __iomem *base;
+	int err;
 
 	guard(mutex)(&ice_mutex);
 
@@ -756,6 +803,34 @@ static int qcom_ice_probe(struct platform_device *pdev)
 		return PTR_ERR(engine);
 	}
 
+	err = devm_pm_opp_set_clkname(&pdev->dev, "core");
+	if (err && err != -ENOENT) {
+		dev_err(&pdev->dev, "Unable to set core clkname to OPP-table\n");
+		/* Store the error pointer for devm_of_qcom_ice_get() */
+		xa_store(&ice_handles, phandle, ERR_PTR(err), GFP_KERNEL);
+		return err;
+	}
+
+	/* OPP table is optional */
+	err = devm_pm_opp_of_add_table(&pdev->dev);
+	if (err && err != -ENODEV) {
+		dev_err(&pdev->dev, "Invalid OPP table in Device tree\n");
+		/* Store the error pointer for devm_of_qcom_ice_get() */
+		xa_store(&ice_handles, phandle, ERR_PTR(err), GFP_KERNEL);
+		return err;
+	}
+
+	/*
+	 * The OPP table is optional. devm_pm_opp_of_add_table() returns
+	 * -ENODEV when no OPP table is present in DT, which is not treated
+	 * as an error. Therefore, track successful OPP registration only
+	 * when err is not -ENODEV.
+	 */
+	if (err == -ENODEV)
+		dev_dbg(&pdev->dev, "ICE OPP table is not registered, please update your DT\n");
+	else
+		engine->has_opp = true;
+
 	xa_store(&ice_handles, phandle, engine, GFP_KERNEL);
 
 	return 0;
diff --git a/include/soc/qcom/ice.h b/include/soc/qcom/ice.h
index 4bee553f0a59d86ec6ce20f7c7b4bce28a706415..4eb58a264d416e71228ed4b13e7f53c549261fdc 100644
--- a/include/soc/qcom/ice.h
+++ b/include/soc/qcom/ice.h
@@ -30,5 +30,7 @@ int qcom_ice_import_key(struct qcom_ice *ice,
 			const u8 *raw_key, size_t raw_key_size,
 			u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]);
 struct qcom_ice *devm_of_qcom_ice_get(struct device *dev);
+int qcom_ice_scale_clk(struct qcom_ice *ice, unsigned long target_freq,
+		       bool round_ceil);
 
 #endif /* __QCOM_ICE_H__ */

-- 
2.34.1