blob: b882f6032feed55e2e9236c5264522ff6bd393bf [file] [log] [blame]
Thierry Reding79c11b62012-08-31 08:29:24 +02001/*
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 bool enabled;
31};
32
33static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
34{
35 return container_of(chip, struct puv3_pwm_chip, chip);
36}
37
38/*
39 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
40 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
41 */
42static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
43 int duty_ns, int period_ns)
44{
45 unsigned long period_cycles, prescale, pv, dc;
46 struct puv3_pwm_chip *puv3 = to_puv3(chip);
47 unsigned long long c;
48
49 c = clk_get_rate(puv3->clk);
50 c = c * period_ns;
51 do_div(c, 1000000000);
52 period_cycles = c;
53
54 if (period_cycles < 1)
55 period_cycles = 1;
56
57 prescale = (period_cycles - 1) / 1024;
58 pv = period_cycles / (prescale + 1) - 1;
59
60 if (prescale > 63)
61 return -EINVAL;
62
63 if (duty_ns == period_ns)
64 dc = OST_PWMDCCR_FDCYCLE;
65 else
66 dc = (pv + 1) * duty_ns / period_ns;
67
68 /*
69 * NOTE: the clock to PWM has to be enabled first
70 * before writing to the registers
71 */
72 clk_prepare_enable(puv3->clk);
73
74 writel(prescale, puv3->base + OST_PWM_PWCR);
75 writel(pv - dc, puv3->base + OST_PWM_DCCR);
76 writel(pv, puv3->base + OST_PWM_PCR);
77
78 clk_disable_unprepare(puv3->clk);
79
80 return 0;
81}
82
83static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
84{
85 struct puv3_pwm_chip *puv3 = to_puv3(chip);
86
87 return clk_prepare_enable(puv3->clk);
88}
89
90static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
91{
92 struct puv3_pwm_chip *puv3 = to_puv3(chip);
93
94 clk_disable_unprepare(puv3->clk);
95}
96
97static const struct pwm_ops puv3_pwm_ops = {
98 .config = puv3_pwm_config,
99 .enable = puv3_pwm_enable,
100 .disable = puv3_pwm_disable,
101 .owner = THIS_MODULE,
102};
103
Bill Pemberton3e9fe832012-11-19 13:23:14 -0500104static int pwm_probe(struct platform_device *pdev)
Thierry Reding79c11b62012-08-31 08:29:24 +0200105{
106 struct puv3_pwm_chip *puv3;
107 struct resource *r;
108 int ret;
109
110 puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
111 if (puv3 == NULL) {
112 dev_err(&pdev->dev, "failed to allocate memory\n");
113 return -ENOMEM;
114 }
115
116 puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
117 if (IS_ERR(puv3->clk))
118 return PTR_ERR(puv3->clk);
119
120 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
121 if (r == NULL) {
122 dev_err(&pdev->dev, "no memory resource defined\n");
123 return -ENODEV;
124 }
125
126 puv3->base = devm_request_and_ioremap(&pdev->dev, r);
127 if (puv3->base == NULL)
128 return -EADDRNOTAVAIL;
129
130 puv3->chip.dev = &pdev->dev;
131 puv3->chip.ops = &puv3_pwm_ops;
132 puv3->chip.base = -1;
133 puv3->chip.npwm = 1;
134
135 ret = pwmchip_add(&puv3->chip);
136 if (ret < 0) {
137 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
138 return ret;
139 }
140
141 platform_set_drvdata(pdev, puv3);
142 return 0;
143}
144
Bill Pemberton77f37912012-11-19 13:26:09 -0500145static int pwm_remove(struct platform_device *pdev)
Thierry Reding79c11b62012-08-31 08:29:24 +0200146{
147 struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
148
149 return pwmchip_remove(&puv3->chip);
150}
151
152static struct platform_driver puv3_pwm_driver = {
153 .driver = {
154 .name = "PKUnity-v3-PWM",
155 },
156 .probe = pwm_probe,
Bill Pembertonfd109112012-11-19 13:21:28 -0500157 .remove = pwm_remove,
Thierry Reding79c11b62012-08-31 08:29:24 +0200158};
159module_platform_driver(puv3_pwm_driver);
160
161MODULE_LICENSE("GPL v2");