1 files changed, 485 insertions, 0 deletions

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
new file mode 100644
index 000000000..7c562559a
--- /dev/null
+++ b/drivers/clk/clk-scmi.c
@@ -0,0 +1,485 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface (SCMI) Protocol based clock driver
+ *
+ * Copyright (C) 2018-2024 ARM Ltd.
+ */
+
+#include <linux/bits.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/scmi_protocol.h>
+
+#define NOT_ATOMIC	false
+#define ATOMIC		true
+
+enum scmi_clk_feats {
+	SCMI_CLK_ATOMIC_SUPPORTED,
+	SCMI_CLK_STATE_CTRL_SUPPORTED,
+	SCMI_CLK_RATE_CTRL_SUPPORTED,
+	SCMI_CLK_PARENT_CTRL_SUPPORTED,
+	SCMI_CLK_DUTY_CYCLE_SUPPORTED,
+	SCMI_CLK_FEATS_COUNT
+};
+
+#define SCMI_MAX_CLK_OPS	BIT(SCMI_CLK_FEATS_COUNT)
+
+static const struct scmi_clk_proto_ops *scmi_proto_clk_ops;
+
+struct scmi_clk {
+	u32 id;
+	struct device *dev;
+	struct clk_hw hw;
+	const struct scmi_clock_info *info;
+	const struct scmi_protocol_handle *ph;
+	struct clk_parent_data *parent_data;
+};
+
+#define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
+
+static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
+					  unsigned long parent_rate)
+{
+	int ret;
+	u64 rate;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	ret = scmi_proto_clk_ops->rate_get(clk->ph, clk->id, &rate);
+	if (ret)
+		return 0;
+	return rate;
+}
+
+static int scmi_clk_determine_rate(struct clk_hw *hw,
+				   struct clk_rate_request *req)
+{
+	int ret;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	/*
+	 * If we could not get a better rate scmi_clk_recalc_rate() will be
+	 * called after the rate is set and we'll know what rate the clock is
+	 * running at then.
+	 */
+	ret = scmi_proto_clk_ops->determine_rate(clk->ph, clk->id, &req->rate);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+			     unsigned long parent_rate)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return scmi_proto_clk_ops->rate_set(clk->ph, clk->id, rate);
+}
+
+static int scmi_clk_set_parent(struct clk_hw *hw, u8 parent_index)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return scmi_proto_clk_ops->parent_set(clk->ph, clk->id, parent_index);
+}
+
+static u8 scmi_clk_get_parent(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+	u32 parent_id, p_idx;
+	int ret;
+
+	ret = scmi_proto_clk_ops->parent_get(clk->ph, clk->id, &parent_id);
+	if (ret)
+		return 0;
+
+	for (p_idx = 0; p_idx < clk->info->num_parents; p_idx++) {
+		if (clk->parent_data[p_idx].index == parent_id)
+			break;
+	}
+
+	if (p_idx == clk->info->num_parents)
+		return 0;
+
+	return p_idx;
+}
+
+static int scmi_clk_enable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return scmi_proto_clk_ops->enable(clk->ph, clk->id, NOT_ATOMIC);
+}
+
+static void scmi_clk_disable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	scmi_proto_clk_ops->disable(clk->ph, clk->id, NOT_ATOMIC);
+}
+
+static int scmi_clk_atomic_enable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return scmi_proto_clk_ops->enable(clk->ph, clk->id, ATOMIC);
+}
+
+static void scmi_clk_atomic_disable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	scmi_proto_clk_ops->disable(clk->ph, clk->id, ATOMIC);
+}
+
+static int __scmi_clk_is_enabled(struct clk_hw *hw, bool atomic)
+{
+	int ret;
+	bool enabled = false;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	ret = scmi_proto_clk_ops->state_get(clk->ph, clk->id, &enabled, atomic);
+	if (ret)
+		dev_warn(clk->dev,
+			 "Failed to get state for clock ID %d\n", clk->id);
+
+	return !!enabled;
+}
+
+static int scmi_clk_atomic_is_enabled(struct clk_hw *hw)
+{
+	return __scmi_clk_is_enabled(hw, ATOMIC);
+}
+
+static int scmi_clk_is_enabled(struct clk_hw *hw)
+{
+	return __scmi_clk_is_enabled(hw, NOT_ATOMIC);
+}
+
+static int scmi_clk_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
+{
+	int ret;
+	u32 val;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	ret = scmi_proto_clk_ops->config_oem_get(clk->ph, clk->id,
+						 SCMI_CLOCK_CFG_DUTY_CYCLE,
+						 &val, NULL, false);
+	if (!ret) {
+		duty->num = val;
+		duty->den = 100;
+	} else {
+		dev_warn(clk->dev,
+			 "Failed to get duty cycle for clock ID %d\n", clk->id);
+	}
+
+	return ret;
+}
+
+static int scmi_clk_set_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
+{
+	int ret;
+	u32 val;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	/* SCMI OEM Duty Cycle is expressed as a percentage */
+	val = (duty->num * 100) / duty->den;
+	ret = scmi_proto_clk_ops->config_oem_set(clk->ph, clk->id,
+						 SCMI_CLOCK_CFG_DUTY_CYCLE,
+						 val, false);
+	if (ret)
+		dev_warn(clk->dev,
+			 "Failed to set duty cycle(%u/%u) for clock ID %d\n",
+			 duty->num, duty->den, clk->id);
+
+	return ret;
+}
+
+static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk,
+			     const struct clk_ops *scmi_ops)
+{
+	int ret;
+
+	struct clk_init_data init = {
+		.flags = CLK_GET_RATE_NOCACHE,
+		.num_parents = sclk->info->num_parents,
+		.ops = scmi_ops,
+		.name = sclk->info->name,
+		.parent_data = sclk->parent_data,
+	};
+
+	sclk->hw.init = &init;
+	ret = devm_clk_hw_register(dev, &sclk->hw);
+	if (ret)
+		return ret;
+
+	clk_hw_set_rate_range(&sclk->hw, sclk->info->min_rate,
+			      sclk->info->max_rate);
+	return ret;
+}
+
+/**
+ * scmi_clk_ops_alloc() - Alloc and configure clock operations
+ * @dev: A device reference for devres
+ * @feats_key: A bitmap representing the desired clk_ops capabilities
+ *
+ * Allocate and configure a proper set of clock operations depending on the
+ * specifically required SCMI clock features.
+ *
+ * Return: A pointer to the allocated and configured clk_ops on success,
+ *	   or NULL on allocation failure.
+ */
+static const struct clk_ops *
+scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
+{
+	struct clk_ops *ops;
+
+	ops = devm_kzalloc(dev, sizeof(*ops), GFP_KERNEL);
+	if (!ops)
+		return NULL;
+	/*
+	 * We can provide enable/disable/is_enabled atomic callbacks only if the
+	 * underlying SCMI transport for an SCMI instance is configured to
+	 * handle SCMI commands in an atomic manner.
+	 *
+	 * When no SCMI atomic transport support is available we instead provide
+	 * only the prepare/unprepare API, as allowed by the clock framework
+	 * when atomic calls are not available.
+	 */
+	if (feats_key & BIT(SCMI_CLK_STATE_CTRL_SUPPORTED)) {
+		if (feats_key & BIT(SCMI_CLK_ATOMIC_SUPPORTED)) {
+			ops->enable = scmi_clk_atomic_enable;
+			ops->disable = scmi_clk_atomic_disable;
+		} else {
+			ops->prepare = scmi_clk_enable;
+			ops->unprepare = scmi_clk_disable;
+		}
+	}
+
+	if (feats_key & BIT(SCMI_CLK_ATOMIC_SUPPORTED))
+		ops->is_enabled = scmi_clk_atomic_is_enabled;
+	else
+		ops->is_prepared = scmi_clk_is_enabled;
+
+	/* Rate ops */
+	ops->recalc_rate = scmi_clk_recalc_rate;
+	ops->determine_rate = scmi_clk_determine_rate;
+	if (feats_key & BIT(SCMI_CLK_RATE_CTRL_SUPPORTED))
+		ops->set_rate = scmi_clk_set_rate;
+
+	/* Parent ops */
+	ops->get_parent = scmi_clk_get_parent;
+	if (feats_key & BIT(SCMI_CLK_PARENT_CTRL_SUPPORTED))
+		ops->set_parent = scmi_clk_set_parent;
+
+	/* Duty cycle */
+	if (feats_key & BIT(SCMI_CLK_DUTY_CYCLE_SUPPORTED)) {
+		ops->get_duty_cycle = scmi_clk_get_duty_cycle;
+		ops->set_duty_cycle = scmi_clk_set_duty_cycle;
+	}
+
+	return ops;
+}
+
+/**
+ * scmi_clk_ops_select() - Select a proper set of clock operations
+ * @sclk: A reference to an SCMI clock descriptor
+ * @atomic_capable: A flag to indicate if atomic mode is supported by the
+ *		    transport
+ * @atomic_threshold_us: Platform atomic threshold value in microseconds:
+ *			 clk_ops are atomic when clock enable latency is less
+ *			 than this threshold
+ * @clk_ops_db: A reference to the array used as a database to store all the
+ *		created clock operations combinations.
+ * @db_size: Maximum number of entries held by @clk_ops_db
+ *
+ * After having built a bitmap descriptor to represent the set of features
+ * needed by this SCMI clock, at first use it to lookup into the set of
+ * previously allocated clk_ops to check if a suitable combination of clock
+ * operations was already created; when no match is found allocate a brand new
+ * set of clk_ops satisfying the required combination of features and save it
+ * for future references.
+ *
+ * In this way only one set of clk_ops is ever created for each different
+ * combination that is effectively needed by a driver instance.
+ *
+ * Return: A pointer to the allocated and configured clk_ops on success, or
+ *	   NULL otherwise.
+ */
+static const struct clk_ops *
+scmi_clk_ops_select(struct scmi_clk *sclk, bool atomic_capable,
+		    unsigned int atomic_threshold_us,
+		    const struct clk_ops **clk_ops_db, size_t db_size)
+{
+	int ret;
+	u32 val;
+	const struct scmi_clock_info *ci = sclk->info;
+	unsigned int feats_key = 0;
+	const struct clk_ops *ops;
+
+	/*
+	 * Note that when transport is atomic but SCMI protocol did not
+	 * specify (or support) an enable_latency associated with a
+	 * clock, we default to use atomic operations mode.
+	 */
+	if (atomic_capable && ci->enable_latency <= atomic_threshold_us)
+		feats_key |= BIT(SCMI_CLK_ATOMIC_SUPPORTED);
+
+	if (!ci->state_ctrl_forbidden)
+		feats_key |= BIT(SCMI_CLK_STATE_CTRL_SUPPORTED);
+
+	if (!ci->rate_ctrl_forbidden)
+		feats_key |= BIT(SCMI_CLK_RATE_CTRL_SUPPORTED);
+
+	if (!ci->parent_ctrl_forbidden)
+		feats_key |= BIT(SCMI_CLK_PARENT_CTRL_SUPPORTED);
+
+	if (ci->extended_config) {
+		ret = scmi_proto_clk_ops->config_oem_get(sclk->ph, sclk->id,
+						 SCMI_CLOCK_CFG_DUTY_CYCLE,
+						 &val, NULL, false);
+		if (!ret)
+			feats_key |= BIT(SCMI_CLK_DUTY_CYCLE_SUPPORTED);
+	}
+
+	if (WARN_ON(feats_key >= db_size))
+		return NULL;
+
+	/* Lookup previously allocated ops */
+	ops = clk_ops_db[feats_key];
+	if (ops)
+		return ops;
+
+	/* Did not find a pre-allocated clock_ops */
+	ops = scmi_clk_ops_alloc(sclk->dev, feats_key);
+	if (!ops)
+		return NULL;
+
+	/* Store new ops combinations */
+	clk_ops_db[feats_key] = ops;
+
+	return ops;
+}
+
+static int scmi_clocks_probe(struct scmi_device *sdev)
+{
+	int idx, count, err;
+	unsigned int atomic_threshold_us;
+	bool transport_is_atomic;
+	struct clk_hw **hws;
+	struct clk_hw_onecell_data *clk_data;
+	struct device *dev = &sdev->dev;
+	struct device_node *np = dev->of_node;
+	const struct scmi_handle *handle = sdev->handle;
+	struct scmi_protocol_handle *ph;
+	const struct clk_ops *scmi_clk_ops_db[SCMI_MAX_CLK_OPS] = {};
+	struct scmi_clk *sclks;
+
+	if (!handle)
+		return -ENODEV;
+
+	scmi_proto_clk_ops =
+		handle->devm_protocol_get(sdev, SCMI_PROTOCOL_CLOCK, &ph);
+	if (IS_ERR(scmi_proto_clk_ops))
+		return PTR_ERR(scmi_proto_clk_ops);
+
+	count = scmi_proto_clk_ops->count_get(ph);
+	if (count < 0) {
+		dev_err(dev, "%pOFn: invalid clock output count\n", np);
+		return -EINVAL;
+	}
+
+	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count),
+				GFP_KERNEL);
+	if (!clk_data)
+		return -ENOMEM;
+
+	clk_data->num = count;
+	hws = clk_data->hws;
+
+	transport_is_atomic = handle->is_transport_atomic(handle,
+							  &atomic_threshold_us);
+
+	sclks = devm_kcalloc(dev, count, sizeof(*sclks), GFP_KERNEL);
+	if (!sclks)
+		return -ENOMEM;
+
+	for (idx = 0; idx < count; idx++)
+		hws[idx] = &sclks[idx].hw;
+
+	for (idx = 0; idx < count; idx++) {
+		struct scmi_clk *sclk = &sclks[idx];
+		const struct clk_ops *scmi_ops;
+
+		sclk->info = scmi_proto_clk_ops->info_get(ph, idx);
+		if (!sclk->info) {
+			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
+			hws[idx] = NULL;
+			continue;
+		}
+
+		sclk->id = idx;
+		sclk->ph = ph;
+		sclk->dev = dev;
+
+		/*
+		 * Note that the scmi_clk_ops_db is on the stack, not global,
+		 * because it cannot be shared between multiple probe-sequences
+		 * to avoid sharing the devm_ allocated clk_ops between multiple
+		 * SCMI clk driver instances.
+		 */
+		scmi_ops = scmi_clk_ops_select(sclk, transport_is_atomic,
+					       atomic_threshold_us,
+					       scmi_clk_ops_db,
+					       ARRAY_SIZE(scmi_clk_ops_db));
+		if (!scmi_ops)
+			return -ENOMEM;
+
+		/* Initialize clock parent data. */
+		if (sclk->info->num_parents > 0) {
+			sclk->parent_data = devm_kcalloc(dev, sclk->info->num_parents,
+							 sizeof(*sclk->parent_data), GFP_KERNEL);
+			if (!sclk->parent_data)
+				return -ENOMEM;
+
+			for (int i = 0; i < sclk->info->num_parents; i++) {
+				sclk->parent_data[i].index = sclk->info->parents[i];
+				sclk->parent_data[i].hw = hws[sclk->info->parents[i]];
+			}
+		}
+
+		err = scmi_clk_ops_init(dev, sclk, scmi_ops);
+		if (err) {
+			dev_err(dev, "failed to register clock %d\n", idx);
+			devm_kfree(dev, sclk->parent_data);
+			hws[idx] = NULL;
+		} else {
+			dev_dbg(dev, "Registered clock:%s%s\n",
+				sclk->info->name,
+				scmi_ops->enable ? " (atomic ops)" : "");
+		}
+	}
+
+	return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
+					   clk_data);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+	{ SCMI_PROTOCOL_CLOCK, "clocks" },
+	{ },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_clocks_driver = {
+	.name = "scmi-clocks",
+	.probe = scmi_clocks_probe,
+	.id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_clocks_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI clock driver");
+MODULE_LICENSE("GPL v2");