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");
156