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 struct pwm_state state; 18 u32 fixed_rate; 19 }; 20 21 static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw) 22 { 23 return container_of(hw, struct clk_pwm, hw); 24 } 25 26 static int clk_pwm_enable(struct clk_hw *hw) 27 { 28 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 29 30 return pwm_apply_atomic(clk_pwm->pwm, &clk_pwm->state); 31 } 32 33 static void clk_pwm_disable(struct clk_hw *hw) 34 { 35 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 36 struct pwm_state state = clk_pwm->state; 37 38 state.enabled = false; 39 40 pwm_apply_atomic(clk_pwm->pwm, &state); 41 } 42 43 static int clk_pwm_prepare(struct clk_hw *hw) 44 { 45 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 46 47 return pwm_apply_might_sleep(clk_pwm->pwm, &clk_pwm->state); 48 } 49 50 static void clk_pwm_unprepare(struct clk_hw *hw) 51 { 52 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 53 54 pwm_disable(clk_pwm->pwm); 55 } 56 57 static unsigned long clk_pwm_recalc_rate(struct clk_hw *hw, 58 unsigned long parent_rate) 59 { 60 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 61 62 return clk_pwm->fixed_rate; 63 } 64 65 static int clk_pwm_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty) 66 { 67 struct clk_pwm *clk_pwm = to_clk_pwm(hw); 68 struct pwm_state state; 69 int ret; 70 71 ret = pwm_get_state_hw(clk_pwm->pwm, &state); 72 if (ret) 73 return ret; 74 75 duty->num = state.duty_cycle; 76 duty->den = state.period; 77 78 return 0; 79 } 80 81 static const struct clk_ops clk_pwm_ops_atomic = { 82 .enable = clk_pwm_enable, 83 .disable = clk_pwm_disable, 84 .recalc_rate = clk_pwm_recalc_rate, 85 .get_duty_cycle = clk_pwm_get_duty_cycle, 86 }; 87 88 static const struct clk_ops clk_pwm_ops = { 89 .prepare = clk_pwm_prepare, 90 .unprepare = clk_pwm_unprepare, 91 .recalc_rate = clk_pwm_recalc_rate, 92 .get_duty_cycle = clk_pwm_get_duty_cycle, 93 }; 94 95 static int clk_pwm_probe(struct platform_device *pdev) 96 { 97 struct device_node *node = pdev->dev.of_node; 98 struct clk_init_data init; 99 struct clk_pwm *clk_pwm; 100 struct pwm_device *pwm; 101 struct pwm_args pargs; 102 const char *clk_name; 103 int ret; 104 105 clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL); 106 if (!clk_pwm) 107 return -ENOMEM; 108 109 pwm = devm_pwm_get(&pdev->dev, NULL); 110 if (IS_ERR(pwm)) 111 return PTR_ERR(pwm); 112 113 pwm_get_args(pwm, &pargs); 114 if (!pargs.period) { 115 dev_err(&pdev->dev, "invalid PWM period\n"); 116 return -EINVAL; 117 } 118 119 if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate)) 120 clk_pwm->fixed_rate = div64_u64(NSEC_PER_SEC, pargs.period); 121 122 if (!clk_pwm->fixed_rate) { 123 dev_err(&pdev->dev, "fixed_rate cannot be zero\n"); 124 return -EINVAL; 125 } 126 127 if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate && 128 pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) { 129 dev_err(&pdev->dev, 130 "clock-frequency does not match PWM period\n"); 131 return -EINVAL; 132 } 133 134 pwm_init_state(pwm, &clk_pwm->state); 135 pwm_set_relative_duty_cycle(&clk_pwm->state, 1, 2); 136 clk_pwm->state.enabled = true; 137 138 clk_name = node->name; 139 of_property_read_string(node, "clock-output-names", &clk_name); 140 141 init.name = clk_name; 142 if (pwm_might_sleep(pwm)) 143 init.ops = &clk_pwm_ops; 144 else 145 init.ops = &clk_pwm_ops_atomic; 146 147 init.flags = 0; 148 init.num_parents = 0; 149 150 clk_pwm->pwm = pwm; 151 clk_pwm->hw.init = &init; 152 ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw); 153 if (ret) 154 return ret; 155 156 return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw); 157 } 158 159 static void clk_pwm_remove(struct platform_device *pdev) 160 { 161 of_clk_del_provider(pdev->dev.of_node); 162 } 163 164 static const struct of_device_id clk_pwm_dt_ids[] = { 165 { .compatible = "pwm-clock" }, 166 { } 167 }; 168 MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids); 169 170 static struct platform_driver clk_pwm_driver = { 171 .probe = clk_pwm_probe, 172 .remove = clk_pwm_remove, 173 .driver = { 174 .name = "pwm-clock", 175 .of_match_table = clk_pwm_dt_ids, 176 }, 177 }; 178 179 module_platform_driver(clk_pwm_driver); 180 181 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>"); 182 MODULE_DESCRIPTION("PWM clock driver"); 183 MODULE_LICENSE("GPL"); 184