Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6-microblaze.git] / drivers / pwm / pwm-puv3.c
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
26 struct puv3_pwm_chip {
27         struct pwm_chip chip;
28         void __iomem *base;
29         struct clk *clk;
30 };
31
32 static 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  */
41 static 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
82 static 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
89 static 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
96 static 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
103 static 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
139 static 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
146 static struct platform_driver puv3_pwm_driver = {
147         .driver = {
148                 .name = "PKUnity-v3-PWM",
149         },
150         .probe = pwm_probe,
151         .remove = pwm_remove,
152 };
153 module_platform_driver(puv3_pwm_driver);
154
155 MODULE_LICENSE("GPL v2");