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 int 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 return 0; 82 } 83 84 static const struct of_device_id of_fixed_mmio_clk_ids[] = { 85 { .compatible = "fixed-mmio-clock" }, 86 { } 87 }; 88 MODULE_DEVICE_TABLE(of, of_fixed_mmio_clk_ids); 89 90 static struct platform_driver of_fixed_mmio_clk_driver = { 91 .driver = { 92 .name = "of_fixed_mmio_clk", 93 .of_match_table = of_fixed_mmio_clk_ids, 94 }, 95 .probe = of_fixed_mmio_clk_probe, 96 .remove = of_fixed_mmio_clk_remove, 97 }; 98 module_platform_driver(of_fixed_mmio_clk_driver); 99 100 MODULE_AUTHOR("Jan Kotas <jank@cadence.com>"); 101 MODULE_DESCRIPTION("Memory Mapped IO Fixed clock driver"); 102 MODULE_LICENSE("GPL v2"); 103