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 void 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
82static const struct of_device_id of_fixed_mmio_clk_ids[] = {
83	{ .compatible = "fixed-mmio-clock" },
84	{ }
85};
86MODULE_DEVICE_TABLE(of, of_fixed_mmio_clk_ids);
87
88static struct platform_driver of_fixed_mmio_clk_driver = {
89	.driver = {
90		.name = "of_fixed_mmio_clk",
91		.of_match_table = of_fixed_mmio_clk_ids,
92	},
93	.probe = of_fixed_mmio_clk_probe,
94	.remove_new = of_fixed_mmio_clk_remove,
95};
96module_platform_driver(of_fixed_mmio_clk_driver);
97
98MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
99MODULE_DESCRIPTION("Memory Mapped IO Fixed clock driver");
100