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16#include <linux/module.h>
17#include <linux/kernel.h>
18#include <linux/platform_device.h>
19#include <linux/slab.h>
20#include <linux/err.h>
21#include <linux/io.h>
22#include <linux/pwm.h>
23#include <linux/delay.h>
24
25#include <asm/div64.h>
26
27#define VT8500_NR_PWMS 4
28
29static DEFINE_MUTEX(pwm_lock);
30static LIST_HEAD(pwm_list);
31
32struct pwm_device {
33 struct list_head node;
34 struct platform_device *pdev;
35
36 const char *label;
37
38 void __iomem *regbase;
39
40 unsigned int use_count;
41 unsigned int pwm_id;
42};
43
44#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
45static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask)
46{
47 int loops = msecs_to_loops(10);
48 while ((readb(reg) & bitmask) && --loops)
49 cpu_relax();
50
51 if (unlikely(!loops))
52 pr_warning("Waiting for status bits 0x%x to clear timed out\n",
53 bitmask);
54}
55
56int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
57{
58 unsigned long long c;
59 unsigned long period_cycles, prescale, pv, dc;
60
61 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
62 return -EINVAL;
63
64 c = 25000000/2;
65 c = c * period_ns;
66 do_div(c, 1000000000);
67 period_cycles = c;
68
69 if (period_cycles < 1)
70 period_cycles = 1;
71 prescale = (period_cycles - 1) / 4096;
72 pv = period_cycles / (prescale + 1) - 1;
73 if (pv > 4095)
74 pv = 4095;
75
76 if (prescale > 1023)
77 return -EINVAL;
78
79 c = (unsigned long long)pv * duty_ns;
80 do_div(c, period_ns);
81 dc = c;
82
83 pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 1));
84 writel(prescale, pwm->regbase + 0x4 + (pwm->pwm_id << 4));
85
86 pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 2));
87 writel(pv, pwm->regbase + 0x8 + (pwm->pwm_id << 4));
88
89 pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 3));
90 writel(dc, pwm->regbase + 0xc + (pwm->pwm_id << 4));
91
92 return 0;
93}
94EXPORT_SYMBOL(pwm_config);
95
96int pwm_enable(struct pwm_device *pwm)
97{
98 pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0));
99 writel(5, pwm->regbase + (pwm->pwm_id << 4));
100 return 0;
101}
102EXPORT_SYMBOL(pwm_enable);
103
104void pwm_disable(struct pwm_device *pwm)
105{
106 pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0));
107 writel(0, pwm->regbase + (pwm->pwm_id << 4));
108}
109EXPORT_SYMBOL(pwm_disable);
110
111struct pwm_device *pwm_request(int pwm_id, const char *label)
112{
113 struct pwm_device *pwm;
114 int found = 0;
115
116 mutex_lock(&pwm_lock);
117
118 list_for_each_entry(pwm, &pwm_list, node) {
119 if (pwm->pwm_id == pwm_id) {
120 found = 1;
121 break;
122 }
123 }
124
125 if (found) {
126 if (pwm->use_count == 0) {
127 pwm->use_count++;
128 pwm->label = label;
129 } else {
130 pwm = ERR_PTR(-EBUSY);
131 }
132 } else {
133 pwm = ERR_PTR(-ENOENT);
134 }
135
136 mutex_unlock(&pwm_lock);
137 return pwm;
138}
139EXPORT_SYMBOL(pwm_request);
140
141void pwm_free(struct pwm_device *pwm)
142{
143 mutex_lock(&pwm_lock);
144
145 if (pwm->use_count) {
146 pwm->use_count--;
147 pwm->label = NULL;
148 } else {
149 pr_warning("PWM device already freed\n");
150 }
151
152 mutex_unlock(&pwm_lock);
153}
154EXPORT_SYMBOL(pwm_free);
155
156static inline void __add_pwm(struct pwm_device *pwm)
157{
158 mutex_lock(&pwm_lock);
159 list_add_tail(&pwm->node, &pwm_list);
160 mutex_unlock(&pwm_lock);
161}
162
163static int __devinit pwm_probe(struct platform_device *pdev)
164{
165 struct pwm_device *pwms;
166 struct resource *r;
167 int ret = 0;
168 int i;
169
170 pwms = kzalloc(sizeof(struct pwm_device) * VT8500_NR_PWMS, GFP_KERNEL);
171 if (pwms == NULL) {
172 dev_err(&pdev->dev, "failed to allocate memory\n");
173 return -ENOMEM;
174 }
175
176 for (i = 0; i < VT8500_NR_PWMS; i++) {
177 pwms[i].use_count = 0;
178 pwms[i].pwm_id = i;
179 pwms[i].pdev = pdev;
180 }
181
182 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
183 if (r == NULL) {
184 dev_err(&pdev->dev, "no memory resource defined\n");
185 ret = -ENODEV;
186 goto err_free;
187 }
188
189 r = request_mem_region(r->start, resource_size(r), pdev->name);
190 if (r == NULL) {
191 dev_err(&pdev->dev, "failed to request memory resource\n");
192 ret = -EBUSY;
193 goto err_free;
194 }
195
196 pwms[0].regbase = ioremap(r->start, resource_size(r));
197 if (pwms[0].regbase == NULL) {
198 dev_err(&pdev->dev, "failed to ioremap() registers\n");
199 ret = -ENODEV;
200 goto err_free_mem;
201 }
202
203 for (i = 1; i < VT8500_NR_PWMS; i++)
204 pwms[i].regbase = pwms[0].regbase;
205
206 for (i = 0; i < VT8500_NR_PWMS; i++)
207 __add_pwm(&pwms[i]);
208
209 platform_set_drvdata(pdev, pwms);
210 return 0;
211
212err_free_mem:
213 release_mem_region(r->start, resource_size(r));
214err_free:
215 kfree(pwms);
216 return ret;
217}
218
219static int __devexit pwm_remove(struct platform_device *pdev)
220{
221 struct pwm_device *pwms;
222 struct resource *r;
223 int i;
224
225 pwms = platform_get_drvdata(pdev);
226 if (pwms == NULL)
227 return -ENODEV;
228
229 mutex_lock(&pwm_lock);
230
231 for (i = 0; i < VT8500_NR_PWMS; i++)
232 list_del(&pwms[i].node);
233 mutex_unlock(&pwm_lock);
234
235 iounmap(pwms[0].regbase);
236
237 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
238 release_mem_region(r->start, resource_size(r));
239
240 kfree(pwms);
241 return 0;
242}
243
244static struct platform_driver pwm_driver = {
245 .driver = {
246 .name = "vt8500-pwm",
247 .owner = THIS_MODULE,
248 },
249 .probe = pwm_probe,
250 .remove = __devexit_p(pwm_remove),
251};
252
253static int __init pwm_init(void)
254{
255 return platform_driver_register(&pwm_driver);
256}
257arch_initcall(pwm_init);
258
259static void __exit pwm_exit(void)
260{
261 platform_driver_unregister(&pwm_driver);
262}
263module_exit(pwm_exit);
264
265MODULE_LICENSE("GPL");
266
