interconnect: add clk-based icc provider support

For some devices it is useful to export clocks as interconnect providers,
if the clock corresponds to bus bandwidth.

For example, on MSM8996 the cluster interconnect clock should be scaled
according to the cluster frequencies. Exporting it as an interconnect
allows one to properly describe this as the cluster bandwidth
requirements.

Tested-by: Yassine Oudjana <y.oudjana@protonmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20230512001334.2983048-3-dmitry.baryshkov@linaro.org
Signed-off-by: Georgi Djakov <djakov@kernel.org>

drivers/interconnect/Kconfig

@@ -15,4 +15,10 @@ source "drivers/interconnect/imx/Kconfig"
 source "drivers/interconnect/qcom/Kconfig"
 source "drivers/interconnect/samsung/Kconfig"
 
+config INTERCONNECT_CLK
+	tristate
+	depends on COMMON_CLK
+	help
+	  Support for wrapping clocks into the interconnect nodes.
+
 endif

drivers/interconnect/Makefile

@@ -7,3 +7,5 @@ obj-$(CONFIG_INTERCONNECT)		+= icc-core.o
 obj-$(CONFIG_INTERCONNECT_IMX)		+= imx/
 obj-$(CONFIG_INTERCONNECT_QCOM)		+= qcom/
 obj-$(CONFIG_INTERCONNECT_SAMSUNG)	+= samsung/
+
+obj-$(CONFIG_INTERCONNECT_CLK)		+= icc-clk.o

drivers/interconnect/icc-clk.c

@@ -0,0 +1,168 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023, Linaro Ltd.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/interconnect-clk.h>
+#include <linux/interconnect-provider.h>
+
+struct icc_clk_node {
+	struct clk *clk;
+	bool enabled;
+};
+
+struct icc_clk_provider {
+	struct icc_provider provider;
+	int num_clocks;
+	struct icc_clk_node clocks[];
+};
+
+#define to_icc_clk_provider(_provider) \
+	container_of(_provider, struct icc_clk_provider, provider)
+
+static int icc_clk_set(struct icc_node *src, struct icc_node *dst)
+{
+	struct icc_clk_node *qn = src->data;
+	int ret;
+
+	if (!qn || !qn->clk)
+		return 0;
+
+	if (!src->peak_bw) {
+		if (qn->enabled)
+			clk_disable_unprepare(qn->clk);
+		qn->enabled = false;
+
+		return 0;
+	}
+
+	if (!qn->enabled) {
+		ret = clk_prepare_enable(qn->clk);
+		if (ret)
+			return ret;
+		qn->enabled = true;
+	}
+
+	return clk_set_rate(qn->clk, icc_units_to_bps(src->peak_bw));
+}
+
+static int icc_clk_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+	struct icc_clk_node *qn = node->data;
+
+	if (!qn || !qn->clk)
+		*peak = INT_MAX;
+	else
+		*peak = Bps_to_icc(clk_get_rate(qn->clk));
+
+	return 0;
+}
+
+/**
+ * icc_clk_register() - register a new clk-based interconnect provider
+ * @dev: device supporting this provider
+ * @first_id: an ID of the first provider's node
+ * @num_clocks: number of instances of struct icc_clk_data
+ * @data: data for the provider
+ *
+ * Registers and returns a clk-based interconnect provider. It is a simple
+ * wrapper around COMMON_CLK framework, allowing other devices to vote on the
+ * clock rate.
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+struct icc_provider *icc_clk_register(struct device *dev,
+				      unsigned int first_id,
+				      unsigned int num_clocks,
+				      const struct icc_clk_data *data)
+{
+	struct icc_clk_provider *qp;
+	struct icc_provider *provider;
+	struct icc_onecell_data *onecell;
+	struct icc_node *node;
+	int ret, i, j;
+
+	onecell = devm_kzalloc(dev, struct_size(onecell, nodes, 2 * num_clocks), GFP_KERNEL);
+	if (!onecell)
+		return ERR_PTR(-ENOMEM);
+
+	qp = devm_kzalloc(dev, struct_size(qp, clocks, num_clocks), GFP_KERNEL);
+	if (!qp)
+		return ERR_PTR(-ENOMEM);
+
+	qp->num_clocks = num_clocks;
+
+	provider = &qp->provider;
+	provider->dev = dev;
+	provider->get_bw = icc_clk_get_bw;
+	provider->set = icc_clk_set;
+	provider->aggregate = icc_std_aggregate;
+	provider->xlate = of_icc_xlate_onecell;
+	INIT_LIST_HEAD(&provider->nodes);
+	provider->data = onecell;
+
+	icc_provider_init(provider);
+
+	for (i = 0, j = 0; i < num_clocks; i++) {
+		qp->clocks[i].clk = data[i].clk;
+
+		node = icc_node_create(first_id + j);
+		if (IS_ERR(node)) {
+			ret = PTR_ERR(node);
+			goto err;
+		}
+
+		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_master", data[i].name);
+		node->data = &qp->clocks[i];
+		icc_node_add(node, provider);
+		/* link to the next node, slave */
+		icc_link_create(node, first_id + j + 1);
+		onecell->nodes[j++] = node;
+
+		node = icc_node_create(first_id + j);
+		if (IS_ERR(node)) {
+			ret = PTR_ERR(node);
+			goto err;
+		}
+
+		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_slave", data[i].name);
+		/* no data for slave node */
+		icc_node_add(node, provider);
+		onecell->nodes[j++] = node;
+	}
+
+	onecell->num_nodes = j;
+
+	ret = icc_provider_register(provider);
+	if (ret)
+		goto err;
+
+	return provider;
+
+err:
+	icc_nodes_remove(provider);
+
+	return ERR_PTR(ret);
+}
+
+/**
+ * icc_clk_unregister() - unregister a previously registered clk interconnect provider
+ * @provider: provider returned by icc_clk_register()
+ */
+void icc_clk_unregister(struct icc_provider *provider)
+{
+	struct icc_clk_provider *qp = container_of(provider, struct icc_clk_provider, provider);
+	int i;
+
+	icc_provider_deregister(&qp->provider);
+	icc_nodes_remove(&qp->provider);
+
+	for (i = 0; i < qp->num_clocks; i++) {
+		struct icc_clk_node *qn = &qp->clocks[i];
+
+		if (qn->enabled)
+			clk_disable_unprepare(qn->clk);
+	}
+}

include/linux/interconnect-clk.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023, Linaro Ltd.
+ */
+
+#ifndef __LINUX_INTERCONNECT_CLK_H
+#define __LINUX_INTERCONNECT_CLK_H
+
+struct device;
+
+struct icc_clk_data {
+	struct clk *clk;
+	const char *name;
+};
+
+struct icc_provider *icc_clk_register(struct device *dev,
+				      unsigned int first_id,
+				      unsigned int num_clocks,
+				      const struct icc_clk_data *data);
+void icc_clk_unregister(struct icc_provider *provider);
+
+#endif