1// SPDX-License-Identifier: GPL-2.0
  2
  3/*
  4 * Memory Mapped IO Fixed clock driver
  5 *
  6 * Copyright (C) 2018 Cadence Design Systems, Inc.
  7 *
  8 * Authors:
  9 *	Jan Kotas <jank@cadence.com>
 10 */
 11
 12#include <linux/clk-provider.h>
 13#include <linux/io.h>
 14#include <linux/module.h>
 15#include <linux/of_address.h>
 16#include <linux/platform_device.h>
 17
 18static struct clk_hw *fixed_mmio_clk_setup(struct device_node *node)
 19{
 20	struct clk_hw *clk;
 21	const char *clk_name = node->name;
 22	void __iomem *base;
 23	u32 freq;
 24	int ret;
 25
 26	base = of_iomap(node, 0);
 27	if (!base) {
 28		pr_err("%pOFn: failed to map address\n", node);
 29		return ERR_PTR(-EIO);
 30	}
 31
 32	freq = readl(base);
 33	iounmap(base);
 34	of_property_read_string(node, "clock-output-names", &clk_name);
 35
 36	clk = clk_hw_register_fixed_rate(NULL, clk_name, NULL, 0, freq);
 37	if (IS_ERR(clk)) {
 38		pr_err("%pOFn: failed to register fixed rate clock\n", node);
 39		return clk;
 40	}
 41
 42	ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, clk);
 43	if (ret) {
 44		pr_err("%pOFn: failed to add clock provider\n", node);
 45		clk_hw_unregister(clk);
 46		clk = ERR_PTR(ret);
 47	}
 48
 49	return clk;
 50}
 51
 52static void __init of_fixed_mmio_clk_setup(struct device_node *node)
 53{
 54	fixed_mmio_clk_setup(node);
 55}
 56CLK_OF_DECLARE(fixed_mmio_clk, "fixed-mmio-clock", of_fixed_mmio_clk_setup);
 57
 58/*
 59 * This is not executed when of_fixed_mmio_clk_setup succeeded.
 60 */
 61static int of_fixed_mmio_clk_probe(struct platform_device *pdev)
 62{
 63	struct clk_hw *clk;
 64
 65	clk = fixed_mmio_clk_setup(pdev->dev.of_node);
 66	if (IS_ERR(clk))
 67		return PTR_ERR(clk);
 68
 69	platform_set_drvdata(pdev, clk);
 70
 71	return 0;
 72}
 73
 74static int of_fixed_mmio_clk_remove(struct platform_device *pdev)
 75{
 76	struct clk_hw *clk = platform_get_drvdata(pdev);
 77
 78	of_clk_del_provider(pdev->dev.of_node);
 79	clk_hw_unregister_fixed_rate(clk);
 80
 81	return 0;
 82}
 83
 84static const struct of_device_id of_fixed_mmio_clk_ids[] = {
 85	{ .compatible = "fixed-mmio-clock" },
 86	{ }
 87};
 88MODULE_DEVICE_TABLE(of, of_fixed_mmio_clk_ids);
 89
 90static struct platform_driver of_fixed_mmio_clk_driver = {
 91	.driver = {
 92		.name = "of_fixed_mmio_clk",
 93		.of_match_table = of_fixed_mmio_clk_ids,
 94	},
 95	.probe = of_fixed_mmio_clk_probe,
 96	.remove = of_fixed_mmio_clk_remove,
 97};
 98module_platform_driver(of_fixed_mmio_clk_driver);
 99
100MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
101MODULE_DESCRIPTION("Memory Mapped IO Fixed clock driver");
102MODULE_LICENSE("GPL v2");