1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
new file mode 100644
index 000000000..fdec715c9
--- /dev/null
+++ b/drivers/clk/clk-scmi.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface (SCMI) Protocol based clock driver
+ *
+ * Copyright (C) 2018-2022 ARM Ltd.
+ */
+
+#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>
+#include <asm/div64.h>
+
+static const struct scmi_clk_proto_ops *scmi_proto_clk_ops;
+
+struct scmi_clk {
+	u32 id;
+	struct clk_hw hw;
+	const struct scmi_clock_info *info;
+	const struct scmi_protocol_handle *ph;
+};
+
+#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 long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *parent_rate)
+{
+	u64 fmin, fmax, ftmp;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	/*
+	 * We can't figure out what rate it will be, so just return the
+	 * rate back to the caller. scmi_clk_recalc_rate() will be called
+	 * after the rate is set and we'll know what rate the clock is
+	 * running at then.
+	 */
+	if (clk->info->rate_discrete)
+		return rate;
+
+	fmin = clk->info->range.min_rate;
+	fmax = clk->info->range.max_rate;
+	if (rate <= fmin)
+		return fmin;
+	else if (rate >= fmax)
+		return fmax;
+
+	ftmp = rate - fmin;
+	ftmp += clk->info->range.step_size - 1; /* to round up */
+	do_div(ftmp, clk->info->range.step_size);
+
+	return ftmp * clk->info->range.step_size + fmin;
+}
+
+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_enable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return scmi_proto_clk_ops->enable(clk->ph, clk->id);
+}
+
+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);
+}
+
+static int scmi_clk_atomic_enable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return scmi_proto_clk_ops->enable_atomic(clk->ph, clk->id);
+}
+
+static void scmi_clk_atomic_disable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	scmi_proto_clk_ops->disable_atomic(clk->ph, clk->id);
+}
+
+/*
+ * We can provide enable/disable 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.
+ *
+ * Two distinct sets of clk_ops are provided since we could have multiple SCMI
+ * instances with different underlying transport quality, so they cannot be
+ * shared.
+ */
+static const struct clk_ops scmi_clk_ops = {
+	.recalc_rate = scmi_clk_recalc_rate,
+	.round_rate = scmi_clk_round_rate,
+	.set_rate = scmi_clk_set_rate,
+	.prepare = scmi_clk_enable,
+	.unprepare = scmi_clk_disable,
+};
+
+static const struct clk_ops scmi_atomic_clk_ops = {
+	.recalc_rate = scmi_clk_recalc_rate,
+	.round_rate = scmi_clk_round_rate,
+	.set_rate = scmi_clk_set_rate,
+	.enable = scmi_clk_atomic_enable,
+	.disable = scmi_clk_atomic_disable,
+};
+
+static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk,
+			     const struct clk_ops *scmi_ops)
+{
+	int ret;
+	unsigned long min_rate, max_rate;
+
+	struct clk_init_data init = {
+		.flags = CLK_GET_RATE_NOCACHE,
+		.num_parents = 0,
+		.ops = scmi_ops,
+		.name = sclk->info->name,
+	};
+
+	sclk->hw.init = &init;
+	ret = devm_clk_hw_register(dev, &sclk->hw);
+	if (ret)
+		return ret;
+
+	if (sclk->info->rate_discrete) {
+		int num_rates = sclk->info->list.num_rates;
+
+		if (num_rates <= 0)
+			return -EINVAL;
+
+		min_rate = sclk->info->list.rates[0];
+		max_rate = sclk->info->list.rates[num_rates - 1];
+	} else {
+		min_rate = sclk->info->range.min_rate;
+		max_rate = sclk->info->range.max_rate;
+	}
+
+	clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate);
+	return ret;
+}
+
+static int scmi_clocks_probe(struct scmi_device *sdev)
+{
+	int idx, count, err;
+	unsigned int atomic_threshold;
+	bool 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;
+
+	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;
+
+	is_atomic = handle->is_transport_atomic(handle, &atomic_threshold);
+
+	for (idx = 0; idx < count; idx++) {
+		struct scmi_clk *sclk;
+		const struct clk_ops *scmi_ops;
+
+		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
+		if (!sclk)
+			return -ENOMEM;
+
+		sclk->info = scmi_proto_clk_ops->info_get(ph, idx);
+		if (!sclk->info) {
+			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
+			devm_kfree(dev, sclk);
+			continue;
+		}
+
+		sclk->id = idx;
+		sclk->ph = ph;
+
+		/*
+		 * 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 (is_atomic &&
+		    sclk->info->enable_latency <= atomic_threshold)
+			scmi_ops = &scmi_atomic_clk_ops;
+		else
+			scmi_ops = &scmi_clk_ops;
+
+		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);
+			hws[idx] = NULL;
+		} else {
+			dev_dbg(dev, "Registered clock:%s%s\n",
+				sclk->info->name,
+				scmi_ops == &scmi_atomic_clk_ops ?
+				" (atomic ops)" : "");
+			hws[idx] = &sclk->hw;
+		}
+	}
+
+	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");