xref: /openbmc/linux/drivers/clk/clk-fixed-mmio.c (revision 6f149b65)
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 
fixed_mmio_clk_setup(struct device_node * node)18 static 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 
of_fixed_mmio_clk_setup(struct device_node * node)52 static void __init of_fixed_mmio_clk_setup(struct device_node *node)
53 {
54 	fixed_mmio_clk_setup(node);
55 }
56 CLK_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  */
of_fixed_mmio_clk_probe(struct platform_device * pdev)61 static 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 
of_fixed_mmio_clk_remove(struct platform_device * pdev)74 static 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 
82 static const struct of_device_id of_fixed_mmio_clk_ids[] = {
83 	{ .compatible = "fixed-mmio-clock" },
84 	{ }
85 };
86 MODULE_DEVICE_TABLE(of, of_fixed_mmio_clk_ids);
87 
88 static 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 };
96 module_platform_driver(of_fixed_mmio_clk_driver);
97 
98 MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
99 MODULE_DESCRIPTION("Memory Mapped IO Fixed clock driver");
100