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"); 102