1/*
  2 * linux/arch/unicore32/kernel/pwm.c
  3 *
  4 * Code specific to PKUnity SoC and UniCore ISA
  5 *
  6 *	Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
  7 *	Copyright (C) 2001-2010 Guan Xuetao
  8 *
  9 * This program is free software; you can redistribute it and/or modify
 10 * it under the terms of the GNU General Public License version 2 as
 11 * published by the Free Software Foundation.
 12 */
 13
 14#include <linux/module.h>
 15#include <linux/kernel.h>
 16#include <linux/platform_device.h>
 17#include <linux/slab.h>
 18#include <linux/err.h>
 19#include <linux/clk.h>
 20#include <linux/io.h>
 21#include <linux/pwm.h>
 22
 23#include <asm/div64.h>
 24#include <mach/hardware.h>
 25
 26struct puv3_pwm_chip {
 27	struct pwm_chip chip;
 28	void __iomem *base;
 29	struct clk *clk;
 30};
 31
 32static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
 33{
 34	return container_of(chip, struct puv3_pwm_chip, chip);
 35}
 36
 37/*
 38 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
 39 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 40 */
 41static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 42			   int duty_ns, int period_ns)
 43{
 44	unsigned long period_cycles, prescale, pv, dc;
 45	struct puv3_pwm_chip *puv3 = to_puv3(chip);
 46	unsigned long long c;
 47
 48	c = clk_get_rate(puv3->clk);
 49	c = c * period_ns;
 50	do_div(c, 1000000000);
 51	period_cycles = c;
 52
 53	if (period_cycles < 1)
 54		period_cycles = 1;
 55
 56	prescale = (period_cycles - 1) / 1024;
 57	pv = period_cycles / (prescale + 1) - 1;
 58
 59	if (prescale > 63)
 60		return -EINVAL;
 61
 62	if (duty_ns == period_ns)
 63		dc = OST_PWMDCCR_FDCYCLE;
 64	else
 65		dc = (pv + 1) * duty_ns / period_ns;
 66
 67	/*
 68	 * NOTE: the clock to PWM has to be enabled first
 69	 * before writing to the registers
 70	 */
 71	clk_prepare_enable(puv3->clk);
 72
 73	writel(prescale, puv3->base + OST_PWM_PWCR);
 74	writel(pv - dc, puv3->base + OST_PWM_DCCR);
 75	writel(pv, puv3->base + OST_PWM_PCR);
 76
 77	clk_disable_unprepare(puv3->clk);
 78
 79	return 0;
 80}
 81
 82static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 83{
 84	struct puv3_pwm_chip *puv3 = to_puv3(chip);
 85
 86	return clk_prepare_enable(puv3->clk);
 87}
 88
 89static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 90{
 91	struct puv3_pwm_chip *puv3 = to_puv3(chip);
 92
 93	clk_disable_unprepare(puv3->clk);
 94}
 95
 96static const struct pwm_ops puv3_pwm_ops = {
 97	.config = puv3_pwm_config,
 98	.enable = puv3_pwm_enable,
 99	.disable = puv3_pwm_disable,
100	.owner = THIS_MODULE,
101};
102
103static int pwm_probe(struct platform_device *pdev)
104{
105	struct puv3_pwm_chip *puv3;
106	struct resource *r;
107	int ret;
108
109	puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
110	if (puv3 == NULL) {
111		dev_err(&pdev->dev, "failed to allocate memory\n");
112		return -ENOMEM;
113	}
114
115	puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
116	if (IS_ERR(puv3->clk))
117		return PTR_ERR(puv3->clk);
118
119	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
120	puv3->base = devm_ioremap_resource(&pdev->dev, r);
121	if (IS_ERR(puv3->base))
122		return PTR_ERR(puv3->base);
123
124	puv3->chip.dev = &pdev->dev;
125	puv3->chip.ops = &puv3_pwm_ops;
126	puv3->chip.base = -1;
127	puv3->chip.npwm = 1;
128
129	ret = pwmchip_add(&puv3->chip);
130	if (ret < 0) {
131		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
132		return ret;
133	}
134
135	platform_set_drvdata(pdev, puv3);
136	return 0;
137}
138
139static int pwm_remove(struct platform_device *pdev)
140{
141	struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
142
143	return pwmchip_remove(&puv3->chip);
144}
145
146static struct platform_driver puv3_pwm_driver = {
147	.driver = {
148		.name = "PKUnity-v3-PWM",
149	},
150	.probe = pwm_probe,
151	.remove = pwm_remove,
152};
153module_platform_driver(puv3_pwm_driver);
154
155MODULE_LICENSE("GPL v2");