cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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clk-pwm.c (3565B)

      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
     14struct clk_pwm {
     15	struct clk_hw hw;
     16	struct pwm_device *pwm;
     17	u32 fixed_rate;
     18};
     19
     20static inline struct clk_pwm *to_clk_pwm(struct clk_hw *hw)
     21{
     22	return container_of(hw, struct clk_pwm, hw);
     23}
     24
     25static 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
     32static 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
     39static 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
     47static int clk_pwm_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
     48{
     49	struct clk_pwm *clk_pwm = to_clk_pwm(hw);
     50	struct pwm_state state;
     51
     52	pwm_get_state(clk_pwm->pwm, &state);
     53
     54	duty->num = state.duty_cycle;
     55	duty->den = state.period;
     56
     57	return 0;
     58}
     59
     60static const struct clk_ops clk_pwm_ops = {
     61	.prepare = clk_pwm_prepare,
     62	.unprepare = clk_pwm_unprepare,
     63	.recalc_rate = clk_pwm_recalc_rate,
     64	.get_duty_cycle = clk_pwm_get_duty_cycle,
     65};
     66
     67static int clk_pwm_probe(struct platform_device *pdev)
     68{
     69	struct device_node *node = pdev->dev.of_node;
     70	struct clk_init_data init;
     71	struct clk_pwm *clk_pwm;
     72	struct pwm_device *pwm;
     73	struct pwm_args pargs;
     74	const char *clk_name;
     75	int ret;
     76
     77	clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
     78	if (!clk_pwm)
     79		return -ENOMEM;
     80
     81	pwm = devm_pwm_get(&pdev->dev, NULL);
     82	if (IS_ERR(pwm))
     83		return PTR_ERR(pwm);
     84
     85	pwm_get_args(pwm, &pargs);
     86	if (!pargs.period) {
     87		dev_err(&pdev->dev, "invalid PWM period\n");
     88		return -EINVAL;
     89	}
     90
     91	if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
     92		clk_pwm->fixed_rate = div64_u64(NSEC_PER_SEC, pargs.period);
     93
     94	if (!clk_pwm->fixed_rate) {
     95		dev_err(&pdev->dev, "fixed_rate cannot be zero\n");
     96		return -EINVAL;
     97	}
     98
     99	if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
    100	    pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
    101		dev_err(&pdev->dev,
    102			"clock-frequency does not match PWM period\n");
    103		return -EINVAL;
    104	}
    105
    106	/*
    107	 * FIXME: pwm_apply_args() should be removed when switching to the
    108	 * atomic PWM API.
    109	 */
    110	pwm_apply_args(pwm);
    111	ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period);
    112	if (ret < 0)
    113		return ret;
    114
    115	clk_name = node->name;
    116	of_property_read_string(node, "clock-output-names", &clk_name);
    117
    118	init.name = clk_name;
    119	init.ops = &clk_pwm_ops;
    120	init.flags = 0;
    121	init.num_parents = 0;
    122
    123	clk_pwm->pwm = pwm;
    124	clk_pwm->hw.init = &init;
    125	ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw);
    126	if (ret)
    127		return ret;
    128
    129	return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw);
    130}
    131
    132static int clk_pwm_remove(struct platform_device *pdev)
    133{
    134	of_clk_del_provider(pdev->dev.of_node);
    135
    136	return 0;
    137}
    138
    139static const struct of_device_id clk_pwm_dt_ids[] = {
    140	{ .compatible = "pwm-clock" },
    141	{ }
    142};
    143MODULE_DEVICE_TABLE(of, clk_pwm_dt_ids);
    144
    145static struct platform_driver clk_pwm_driver = {
    146	.probe = clk_pwm_probe,
    147	.remove = clk_pwm_remove,
    148	.driver = {
    149		.name = "pwm-clock",
    150		.of_match_table = clk_pwm_dt_ids,
    151	},
    152};
    153
    154module_platform_driver(clk_pwm_driver);
    155
    156MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
    157MODULE_DESCRIPTION("PWM clock driver");
    158MODULE_LICENSE("GPL");