1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * linux/arch/unicore32/kernel/pwm.c
  4 *
  5 * Code specific to PKUnity SoC and UniCore ISA
  6 *
  7 *	Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
  8 *	Copyright (C) 2001-2010 Guan Xuetao
  9 */
 10
 11#include <linux/module.h>
 12#include <linux/kernel.h>
 13#include <linux/platform_device.h>
 14#include <linux/slab.h>
 15#include <linux/err.h>
 16#include <linux/clk.h>
 17#include <linux/io.h>
 18#include <linux/pwm.h>
 19
 20#include <asm/div64.h>
 21#include <mach/hardware.h>
 22
 23struct puv3_pwm_chip {
 24	struct pwm_chip chip;
 25	void __iomem *base;
 26	struct clk *clk;
 27};
 28
 29static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
 30{
 31	return container_of(chip, struct puv3_pwm_chip, chip);
 32}
 33
 34/*
 35 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
 36 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 37 */
 38static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 39			   int duty_ns, int period_ns)
 40{
 41	unsigned long period_cycles, prescale, pv, dc;
 42	struct puv3_pwm_chip *puv3 = to_puv3(chip);
 43	unsigned long long c;
 44
 45	c = clk_get_rate(puv3->clk);
 46	c = c * period_ns;
 47	do_div(c, 1000000000);
 48	period_cycles = c;
 49
 50	if (period_cycles < 1)
 51		period_cycles = 1;
 52
 53	prescale = (period_cycles - 1) / 1024;
 54	pv = period_cycles / (prescale + 1) - 1;
 55
 56	if (prescale > 63)
 57		return -EINVAL;
 58
 59	if (duty_ns == period_ns)
 60		dc = OST_PWMDCCR_FDCYCLE;
 61	else
 62		dc = (pv + 1) * duty_ns / period_ns;
 63
 64	/*
 65	 * NOTE: the clock to PWM has to be enabled first
 66	 * before writing to the registers
 67	 */
 68	clk_prepare_enable(puv3->clk);
 69
 70	writel(prescale, puv3->base + OST_PWM_PWCR);
 71	writel(pv - dc, puv3->base + OST_PWM_DCCR);
 72	writel(pv, puv3->base + OST_PWM_PCR);
 73
 74	clk_disable_unprepare(puv3->clk);
 75
 76	return 0;
 77}
 78
 79static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 80{
 81	struct puv3_pwm_chip *puv3 = to_puv3(chip);
 82
 83	return clk_prepare_enable(puv3->clk);
 84}
 85
 86static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 87{
 88	struct puv3_pwm_chip *puv3 = to_puv3(chip);
 89
 90	clk_disable_unprepare(puv3->clk);
 91}
 92
 93static const struct pwm_ops puv3_pwm_ops = {
 94	.config = puv3_pwm_config,
 95	.enable = puv3_pwm_enable,
 96	.disable = puv3_pwm_disable,
 97	.owner = THIS_MODULE,
 98};
 99
100static int pwm_probe(struct platform_device *pdev)
101{
102	struct puv3_pwm_chip *puv3;
103	struct resource *r;
104	int ret;
105
106	puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
107	if (!puv3)
108		return -ENOMEM;
109
110	puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
111	if (IS_ERR(puv3->clk))
112		return PTR_ERR(puv3->clk);
113
114	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
115	puv3->base = devm_ioremap_resource(&pdev->dev, r);
116	if (IS_ERR(puv3->base))
117		return PTR_ERR(puv3->base);
118
119	puv3->chip.dev = &pdev->dev;
120	puv3->chip.ops = &puv3_pwm_ops;
121	puv3->chip.base = -1;
122	puv3->chip.npwm = 1;
123
124	ret = pwmchip_add(&puv3->chip);
125	if (ret < 0) {
126		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
127		return ret;
128	}
129
130	platform_set_drvdata(pdev, puv3);
131	return 0;
132}
133
134static int pwm_remove(struct platform_device *pdev)
135{
136	struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
137
138	return pwmchip_remove(&puv3->chip);
139}
140
141static struct platform_driver puv3_pwm_driver = {
142	.driver = {
143		.name = "PKUnity-v3-PWM",
144	},
145	.probe = pwm_probe,
146	.remove = pwm_remove,
147};
148module_platform_driver(puv3_pwm_driver);
149
150MODULE_LICENSE("GPL v2");