1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2014 Philipp Zabel, Pengutronix 4 * 5 * PWM (mis)used as clock output 6 */ 7 #include <linux/clk-provider.h> 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/of.h> 11 #include <linux/platform_device.h> 12 #include <linux/pwm.h> 13 14 struct clk_pwm { 15 struct clk_hw hw; 16 struct pwm_device *pwm; 17 u32 fixed_rate; 18 }; 19 20 static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw) 21 { 22 return container_of(hw, struct clk_pwm, hw); 23 } 24 25 static int clk_pwm_prepare(struct clk_hw *hw) 26 { 27 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 28 29 return pwm_enable(clk_pwm->pwm); 30 } 31 32 static void clk_pwm_unprepare(struct clk_hw *hw) 33 { 34 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 35 36 pwm_disable(clk_pwm->pwm); 37 } 38 39 static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw, 40 unsigned long parent_rate) 41 { 42 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 43 44 return clk_pwm->fixed_rate; 45 } 46 47 static const struct clk_ops clk_pwm_ops = { 48 .prepare = clk_pwm_prepare, 49 .unprepare = clk_pwm_unprepare, 50 .recalc_rate = clk_pwm_recalc_rate, 51 }; 52 53 static int clk_pwm_probe(struct platform_device *pdev) 54 { 55 struct device_node *node = pdev->dev.of_node; 56 struct clk_init_data init; 57 struct clk_pwm *clk_pwm; 58 struct pwm_device *pwm; 59 struct pwm_args pargs; 60 const char *clk_name; 61 int ret; 62 63 clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL); 64 if (!clk_pwm) 65 return -ENOMEM; 66 67 pwm = devm_pwm_get(&pdev->dev, NULL); 68 if (IS_ERR(pwm)) 69 return PTR_ERR(pwm); 70 71 pwm_get_args(pwm, &pargs); 72 if (!pargs.period) { 73 dev_err(&pdev->dev, "invalid PWM period\n"); 74 return -EINVAL; 75 } 76 77 if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate)) 78 clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period; 79 80 if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate && 81 pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) { 82 dev_err(&pdev->dev, 83 "clock-frequency does not match PWM period\n"); 84 return -EINVAL; 85 } 86 87 /* 88 * FIXME: pwm_apply_args() should be removed when switching to the 89 * atomic PWM API. 90 */ 91 pwm_apply_args(pwm); 92 ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period); 93 if (ret < 0) 94 return ret; 95 96 clk_name = node->name; 97 of_property_read_string(node, "clock-output-names", &clk_name); 98 99 init.name = clk_name; 100 init.ops = &clk_pwm_ops; 101 init.flags = 0; 102 init.num_parents = 0; 103 104 clk_pwm->pwm = pwm; 105 clk_pwm->hw.init = &init; 106 ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw); 107 if (ret) 108 return ret; 109 110 return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw); 111 } 112 113 static int clk_pwm_remove(struct platform_device *pdev) 114 { 115 of_clk_del_provider(pdev->dev.of_node); 116 117 return 0; 118 } 119 120 static const struct of_device_id clk_pwm_dt_ids[] = { 121 { .compatible = "pwm-clock" }, 122 { } 123 }; 124 MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids); 125 126 static struct platform_driver clk_pwm_driver = { 127 .probe = clk_pwm_probe, 128 .remove = clk_pwm_remove, 129 .driver = { 130 .name = "pwm-clock", 131 .of_match_table = of_match_ptr(clk_pwm_dt_ids), 132 }, 133 }; 134 135 module_platform_driver(clk_pwm_driver); 136 137 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>"); 138 MODULE_DESCRIPTION("PWM clock driver"); 139 MODULE_LICENSE("GPL"); 140