2 * linux/arch/unicore32/kernel/pwm.c
4 * Code specific to PKUnity SoC and UniCore ISA
6 * Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
7 * Copyright (C) 2001-2010 Guan Xuetao
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.
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>
21 #include <linux/pwm.h>
23 #include <asm/div64.h>
24 #include <mach/hardware.h>
27 struct list_head node;
28 struct platform_device *pdev;
34 unsigned int use_count;
39 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
40 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
42 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
45 unsigned long period_cycles, prescale, pv, dc;
47 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
50 c = clk_get_rate(pwm->clk);
52 do_div(c, 1000000000);
55 if (period_cycles < 1)
57 prescale = (period_cycles - 1) / 1024;
58 pv = period_cycles / (prescale + 1) - 1;
63 if (duty_ns == period_ns)
64 dc = OST_PWMDCCR_FDCYCLE;
66 dc = (pv + 1) * duty_ns / period_ns;
68 /* NOTE: the clock to PWM has to be enabled first
69 * before writing to the registers
72 OST_PWMPWCR = prescale;
73 OST_PWMDCCR = pv - dc;
75 clk_disable(pwm->clk);
79 EXPORT_SYMBOL(pwm_config);
81 int pwm_enable(struct pwm_device *pwm)
85 if (!pwm->clk_enabled) {
86 rc = clk_enable(pwm->clk);
92 EXPORT_SYMBOL(pwm_enable);
94 void pwm_disable(struct pwm_device *pwm)
96 if (pwm->clk_enabled) {
97 clk_disable(pwm->clk);
101 EXPORT_SYMBOL(pwm_disable);
103 static DEFINE_MUTEX(pwm_lock);
104 static LIST_HEAD(pwm_list);
106 struct pwm_device *pwm_request(int pwm_id, const char *label)
108 struct pwm_device *pwm;
111 mutex_lock(&pwm_lock);
113 list_for_each_entry(pwm, &pwm_list, node) {
114 if (pwm->pwm_id == pwm_id) {
121 if (pwm->use_count == 0) {
125 pwm = ERR_PTR(-EBUSY);
127 pwm = ERR_PTR(-ENOENT);
129 mutex_unlock(&pwm_lock);
132 EXPORT_SYMBOL(pwm_request);
134 void pwm_free(struct pwm_device *pwm)
136 mutex_lock(&pwm_lock);
138 if (pwm->use_count) {
142 pr_warning("PWM device already freed\n");
144 mutex_unlock(&pwm_lock);
146 EXPORT_SYMBOL(pwm_free);
148 static inline void __add_pwm(struct pwm_device *pwm)
150 mutex_lock(&pwm_lock);
151 list_add_tail(&pwm->node, &pwm_list);
152 mutex_unlock(&pwm_lock);
155 static struct pwm_device *pwm_probe(struct platform_device *pdev,
156 unsigned int pwm_id, struct pwm_device *parent_pwm)
158 struct pwm_device *pwm;
162 pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
164 dev_err(&pdev->dev, "failed to allocate memory\n");
165 return ERR_PTR(-ENOMEM);
168 pwm->clk = clk_get(NULL, "OST_CLK");
169 if (IS_ERR(pwm->clk)) {
170 ret = PTR_ERR(pwm->clk);
173 pwm->clk_enabled = 0;
176 pwm->pwm_id = pwm_id;
179 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
181 dev_err(&pdev->dev, "no memory resource defined\n");
186 r = request_mem_region(r->start, resource_size(r), pdev->name);
188 dev_err(&pdev->dev, "failed to request memory resource\n");
194 platform_set_drvdata(pdev, pwm);
204 static int __devinit puv3_pwm_probe(struct platform_device *pdev)
206 struct pwm_device *pwm = pwm_probe(pdev, pdev->id, NULL);
214 static int __devexit pwm_remove(struct platform_device *pdev)
216 struct pwm_device *pwm;
219 pwm = platform_get_drvdata(pdev);
223 mutex_lock(&pwm_lock);
224 list_del(&pwm->node);
225 mutex_unlock(&pwm_lock);
227 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
228 release_mem_region(r->start, resource_size(r));
235 static struct platform_driver puv3_pwm_driver = {
237 .name = "PKUnity-v3-PWM",
239 .probe = puv3_pwm_probe,
240 .remove = __devexit_p(pwm_remove),
243 static int __init pwm_init(void)
247 ret = platform_driver_register(&puv3_pwm_driver);
249 printk(KERN_ERR "failed to register puv3_pwm_driver\n");
255 arch_initcall(pwm_init);
257 static void __exit pwm_exit(void)
259 platform_driver_unregister(&puv3_pwm_driver);
261 module_exit(pwm_exit);
263 MODULE_LICENSE("GPL v2");