tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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)
111 return -ENOMEM;
112
113 puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
114 if (IS_ERR(puv3->clk))
115 return PTR_ERR(puv3->clk);
116
117 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
118 puv3->base = devm_ioremap_resource(&pdev->dev, r);
119 if (IS_ERR(puv3->base))
120 return PTR_ERR(puv3->base);
121
122 puv3->chip.dev = &pdev->dev;
123 puv3->chip.ops = &puv3_pwm_ops;
124 puv3->chip.base = -1;
125 puv3->chip.npwm = 1;
126
127 ret = pwmchip_add(&puv3->chip);
128 if (ret < 0) {
129 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
130 return ret;
131 }
132
133 platform_set_drvdata(pdev, puv3);
134 return 0;
135}
136
137static int pwm_remove(struct platform_device *pdev)
138{
139 struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
140
141 return pwmchip_remove(&puv3->chip);
142}
143
144static struct platform_driver puv3_pwm_driver = {
145 .driver = {
146 .name = "PKUnity-v3-PWM",
147 },
148 .probe = pwm_probe,
149 .remove = pwm_remove,
150};
151module_platform_driver(puv3_pwm_driver);
152
153MODULE_LICENSE("GPL v2");