drivers/clk/clk-fixed-mmio.c

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