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, index: 0);
27 if (!base) {
28 pr_err("%pOFn: failed to map address\n", node);
29 return ERR_PTR(error: -EIO);
30 }
31
32 freq = readl(addr: base);
33 iounmap(addr: base);
34 of_property_read_string(np: node, propname: "clock-output-names", out_string: &clk_name);
35
36 clk = clk_hw_register_fixed_rate(NULL, clk_name, NULL, 0, freq);
37 if (IS_ERR(ptr: 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(np: node, get: of_clk_hw_simple_get, data: clk);
43 if (ret) {
44 pr_err("%pOFn: failed to add clock provider\n", node);
45 clk_hw_unregister(hw: clk);
46 clk = ERR_PTR(error: 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(node: pdev->dev.of_node);
66 if (IS_ERR(ptr: clk))
67 return PTR_ERR(ptr: clk);
68
69 platform_set_drvdata(pdev, data: 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(np: pdev->dev.of_node);
79 clk_hw_unregister_fixed_rate(hw: 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

source code of linux/drivers/clk/clk-fixed-mmio.c