--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP
+ */
+
+#include <linux/clk.h>
+#include <linux/devfreq.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct imx_bus {
+ struct devfreq_dev_profile profile;
+ struct devfreq *devfreq;
+ struct clk *clk;
+};
+
+static int imx_bus_target(struct device *dev,
+ unsigned long *freq, u32 flags)
+{
+ struct dev_pm_opp *new_opp;
+ int ret;
+
+ new_opp = devfreq_recommended_opp(dev, freq, flags);
+ if (IS_ERR(new_opp)) {
+ ret = PTR_ERR(new_opp);
+ dev_err(dev, "failed to get recommended opp: %d\n", ret);
+ return ret;
+ }
+ dev_pm_opp_put(new_opp);
+
+ return dev_pm_opp_set_rate(dev, *freq);
+}
+
+static int imx_bus_get_cur_freq(struct device *dev, unsigned long *freq)
+{
+ struct imx_bus *priv = dev_get_drvdata(dev);
+
+ *freq = clk_get_rate(priv->clk);
+
+ return 0;
+}
+
+static int imx_bus_get_dev_status(struct device *dev,
+ struct devfreq_dev_status *stat)
+{
+ struct imx_bus *priv = dev_get_drvdata(dev);
+
+ stat->busy_time = 0;
+ stat->total_time = 0;
+ stat->current_frequency = clk_get_rate(priv->clk);
+
+ return 0;
+}
+
+static void imx_bus_exit(struct device *dev)
+{
+ dev_pm_opp_of_remove_table(dev);
+}
+
+static int imx_bus_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct imx_bus *priv;
+ const char *gov = DEVFREQ_GOV_USERSPACE;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ /*
+ * Fetch the clock to adjust but don't explicitly enable.
+ *
+ * For imx bus clock clk_set_rate is safe no matter if the clock is on
+ * or off and some peripheral side-buses might be off unless enabled by
+ * drivers for devices on those specific buses.
+ *
+ * Rate adjustment on a disabled bus clock just takes effect later.
+ */
+ priv->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk)) {
+ ret = PTR_ERR(priv->clk);
+ dev_err(dev, "failed to fetch clk: %d\n", ret);
+ return ret;
+ }
+ platform_set_drvdata(pdev, priv);
+
+ ret = dev_pm_opp_of_add_table(dev);
+ if (ret < 0) {
+ dev_err(dev, "failed to get OPP table\n");
+ return ret;
+ }
+
+ priv->profile.polling_ms = 1000;
+ priv->profile.target = imx_bus_target;
+ priv->profile.get_dev_status = imx_bus_get_dev_status;
+ priv->profile.exit = imx_bus_exit;
+ priv->profile.get_cur_freq = imx_bus_get_cur_freq;
+ priv->profile.initial_freq = clk_get_rate(priv->clk);
+
+ priv->devfreq = devm_devfreq_add_device(dev, &priv->profile,
+ gov, NULL);
+ if (IS_ERR(priv->devfreq)) {
+ ret = PTR_ERR(priv->devfreq);
+ dev_err(dev, "failed to add devfreq device: %d\n", ret);
+ goto err;
+ }
+
+ return 0;
+
+err:
+ dev_pm_opp_of_remove_table(dev);
+ return ret;
+}
+
+static const struct of_device_id imx_bus_of_match[] = {
+ { .compatible = "fsl,imx8m-noc", },
+ { .compatible = "fsl,imx8m-nic", },
+ { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, imx_bus_of_match);
+
+static struct platform_driver imx_bus_platdrv = {
+ .probe = imx_bus_probe,
+ .driver = {
+ .name = "imx-bus-devfreq",
+ .of_match_table = of_match_ptr(imx_bus_of_match),
+ },
+};
+module_platform_driver(imx_bus_platdrv);
+
+MODULE_DESCRIPTION("Generic i.MX bus frequency scaling driver");
+MODULE_AUTHOR("Leonard Crestez <leonard.crestez@nxp.com>");
+MODULE_LICENSE("GPL v2");