[PATCH v3 2/4] clk: qcom: Add generic clkref_en support

Qiang Yu
2026-05-06T08:44:05Z

Before XO refclk is distributed to PCIe/USB/eDP PHYs, it passes through
a QREF block. QREF is powered by dedicated LDO rails, and the clkref_en
register controls whether refclk is gated through to the PHY side.

These clkref controls are different from typical GCC branch clocks:
- only a single enable bit is present, without branch-style config bits
- regulators must be voted before enable and unvoted after disable

Model this as a dedicated clk_ref clock type with custom clk_ops instead
of reusing struct clk_branch semantics.

Also provide a common registration/probe API so the same clkref model
can be reused regardless of where clkref_en registers are placed, e.g.
TCSR on glymur and TLMM on SM8750.

Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
---
drivers/clk/qcom/Makefile | 1 +
drivers/clk/qcom/clk-ref.c | 202 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/clk/qcom.h | 69 ++++++++++++++++
3 files changed, 272 insertions(+)

diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index 89d07c35e4d9..1659e9d9afa9 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -8,6 +8,7 @@ clk-qcom-y += clk-pll.o
clk-qcom-y += clk-rcg.o
clk-qcom-y += clk-rcg2.o
clk-qcom-y += clk-branch.o
+clk-qcom-y += clk-ref.o
clk-qcom-y += clk-regmap-divider.o
clk-qcom-y += clk-regmap-mux.o
clk-qcom-y += clk-regmap-mux-div.o
diff --git a/drivers/clk/qcom/clk-ref.c b/drivers/clk/qcom/clk-ref.c
new file mode 100644
index 000000000000..ea2ed03460f2
--- /dev/null
+++ b/drivers/clk/qcom/clk-ref.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026, Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clk/qcom.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define QCOM_CLK_REF_EN_MASK BIT(0)
+
+struct qcom_clk_ref_provider {
+ struct qcom_clk_ref *refs;
+ size_t num_refs;
+};
+
+static inline struct qcom_clk_ref *to_qcom_clk_ref(struct clk_hw *hw)
+{
+ return container_of(hw, struct qcom_clk_ref, hw);
+}
+
+static const struct clk_parent_data qcom_clk_ref_parent_data = {
+ .index = 0,
+};
+
+static int qcom_clk_ref_prepare(struct clk_hw *hw)
+{
+ struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+ int ret;
+
+ if (!rclk->desc.num_regulators)
+ return 0;
+
+ ret = regulator_bulk_enable(rclk->desc.num_regulators, rclk->regulators);
+ if (ret)
+ pr_err("Failed to enable regulators for %s: %d\n",
+ clk_hw_get_name(hw), ret);
+
+ return ret;
+}
+
+static void qcom_clk_ref_unprepare(struct clk_hw *hw)
+{
+ struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+
+ if (rclk->desc.num_regulators)
+ regulator_bulk_disable(rclk->desc.num_regulators, rclk->regulators);
+}
+
+static int qcom_clk_ref_enable(struct clk_hw *hw)
+{
+ struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+ int ret;
+
+ ret = regmap_update_bits(rclk->regmap, rclk->desc.offset, QCOM_CLK_REF_EN_MASK,
+ QCOM_CLK_REF_EN_MASK);
+ if (ret)
+ return ret;
+
+ udelay(10);
+
+ return 0;
+}
+
+static void qcom_clk_ref_disable(struct clk_hw *hw)
+{
+ struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+
+ regmap_update_bits(rclk->regmap, rclk->desc.offset, QCOM_CLK_REF_EN_MASK, 0);
+ udelay(10);
+}
+
+static int qcom_clk_ref_is_enabled(struct clk_hw *hw)
+{
+ struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+ u32 val;
+ int ret;
+
+ ret = regmap_read(rclk->regmap, rclk->desc.offset, &val);
+ if (ret)
+ return ret;
+
+ return !!(val & QCOM_CLK_REF_EN_MASK);
+}
+
+static const struct clk_ops qcom_clk_ref_ops = {
+ .prepare = qcom_clk_ref_prepare,
+ .unprepare = qcom_clk_ref_unprepare,
+ .enable = qcom_clk_ref_enable,
+ .disable = qcom_clk_ref_disable,
+ .is_enabled = qcom_clk_ref_is_enabled,
+};
+
+static int qcom_clk_ref_register(struct device *dev, struct regmap *regmap,
+ struct qcom_clk_ref *clk_refs,
+ const struct qcom_clk_ref_desc *descs,
+ size_t num_clk_refs)
+{
+ const struct qcom_clk_ref_desc *desc;
+ struct qcom_clk_ref *clk_ref;
+ size_t clk_idx;
+ unsigned int i;
+ int ret;
+
+ for (clk_idx = 0; clk_idx < num_clk_refs; clk_idx++) {
+ clk_ref = &clk_refs[clk_idx];
+ desc = &descs[clk_idx];
+
+ if (!desc->name)
+ return -EINVAL;
+
+ clk_ref->regmap = regmap;
+ clk_ref->desc = *desc;
+
+ if (clk_ref->desc.num_regulators) {
+ clk_ref->regulators = devm_kcalloc(dev, clk_ref->desc.num_regulators,
+ sizeof(*clk_ref->regulators),
+ GFP_KERNEL);
+ if (!clk_ref->regulators)
+ return -ENOMEM;
+
+ for (i = 0; i < clk_ref->desc.num_regulators; i++)
+ clk_ref->regulators[i].supply =
+ clk_ref->desc.regulator_names[i];
+
+ ret = devm_regulator_bulk_get(dev, clk_ref->desc.num_regulators,
+ clk_ref->regulators);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to get regulators for %s\n",
+ clk_ref->desc.name);
+ }
+
+ clk_ref->init_data.name = clk_ref->desc.name;
+ clk_ref->init_data.parent_data = &qcom_clk_ref_parent_data;
+ clk_ref->init_data.num_parents = 1;
+ clk_ref->init_data.ops = &qcom_clk_ref_ops;
+ clk_ref->hw.init = &clk_ref->init_data;
+
+ ret = devm_clk_hw_register(dev, &clk_ref->hw);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static struct clk_hw *qcom_clk_ref_provider_get(struct of_phandle_args *clkspec, void *data)
+{
+ struct qcom_clk_ref_provider *provider = data;
+ unsigned int idx = clkspec->args[0];
+
+ if (idx >= provider->num_refs)
+ return ERR_PTR(-EINVAL);
+
+ return &provider->refs[idx].hw;
+}
+
+int qcom_clk_ref_probe(struct platform_device *pdev,
+ const struct regmap_config *config,
+ const struct qcom_clk_ref_desc *descs,
+ size_t num_clk_refs)
+{
+ struct qcom_clk_ref_provider *provider;
+ struct device *dev = &pdev->dev;
+ struct regmap *regmap;
+ void __iomem *base;
+ int ret;
+
+ base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ regmap = devm_regmap_init_mmio(dev, base, config);
+ if (IS_ERR(regmap))
+ return PTR_ERR(regmap);
+
+ provider = devm_kzalloc(dev, sizeof(*provider), GFP_KERNEL);
+ if (!provider)
+ return -ENOMEM;
+
+ provider->refs = devm_kcalloc(dev, num_clk_refs, sizeof(*provider->refs),
+ GFP_KERNEL);
+ if (!provider->refs)
+ return -ENOMEM;
+
+ provider->num_refs = num_clk_refs;
+
+ ret = qcom_clk_ref_register(dev, regmap, provider->refs, descs,
+ provider->num_refs);
+ if (ret)
+ return ret;
+
+ return devm_of_clk_add_hw_provider(dev, qcom_clk_ref_provider_get, provider);
+}
+EXPORT_SYMBOL_GPL(qcom_clk_ref_probe);
diff --git a/include/linux/clk/qcom.h b/include/linux/clk/qcom.h
new file mode 100644
index 000000000000..09e2e3178cfb
--- /dev/null
+++ b/include/linux/clk/qcom.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2026, Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#ifndef __LINUX_CLK_QCOM_H
+#define __LINUX_CLK_QCOM_H
+
+#include <linux/clk-provider.h>
+#include <linux/errno.h>
+#include <linux/kconfig.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+struct device;
+struct platform_device;
+struct regulator_bulk_data;
+
+/**
+ * struct qcom_clk_ref_desc - descriptor for a clkref_en gate clock
+ * @name: clock name exposed to the common clock framework
+ * @offset: clkref_en register offset from the block base
+ * @regulator_names: optional supply names enabled while preparing the clock
+ * @num_regulators: number of entries in @regulator_names
+ */
+struct qcom_clk_ref_desc {
+ const char *name;
+ u32 offset;
+ const char * const *regulator_names;
+ unsigned int num_regulators;
+};
+
+/**
+ * struct qcom_clk_ref - per-clock data for a clkref_en gate clock
+ * @hw: common clock framework hardware clock handle
+ * @init_data: common clock framework registration data
+ * @regmap: register map backing the clkref_en register
+ * @desc: clock descriptor copied at registration time
+ * @regulators: optional bulk regulator handles for @desc.regulator_names
+ */
+struct qcom_clk_ref {
+ struct clk_hw hw;
+ struct clk_init_data init_data;
+ struct regmap *regmap;
+ struct qcom_clk_ref_desc desc;
+ struct regulator_bulk_data *regulators;
+};
+
+#if IS_ENABLED(CONFIG_COMMON_CLK_QCOM)
+
+int qcom_clk_ref_probe(struct platform_device *pdev,
+ const struct regmap_config *config,
+ const struct qcom_clk_ref_desc *descs,
+ size_t num_clk_refs);
+
+#else
+
+static inline int
+qcom_clk_ref_probe(struct platform_device *pdev,
+ const struct regmap_config *config,
+ const struct qcom_clk_ref_desc *descs,
+ size_t num_clk_refs)
+{
+ return -EOPNOTSUPP;
+}
+
+#endif
+
+#endif

--
2.34.1