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/io.h>
  14 #include <linux/module.h>
  15 #include <linux/of_address.h>
  16 #include <linux/platform_device.h>
  17
  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
  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  */
  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
  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 = 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");