ARM:imx:fix pwm period value
[linux-2.6.git] / arch / arm / plat-mxc / pwm.c
1 /*
2  * simple driver for PWM (Pulse Width Modulator) controller
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
9  */
10
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/platform_device.h>
14 #include <linux/slab.h>
15 #include <linux/err.h>
16 #include <linux/clk.h>
17 #include <linux/io.h>
18 #include <linux/pwm.h>
19 #include <mach/hardware.h>
20
21
22 /* i.MX1 and i.MX21 share the same PWM function block: */
23
24 #define MX1_PWMC    0x00   /* PWM Control Register */
25 #define MX1_PWMS    0x04   /* PWM Sample Register */
26 #define MX1_PWMP    0x08   /* PWM Period Register */
27
28
29 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
30
31 #define MX3_PWMCR                 0x00    /* PWM Control Register */
32 #define MX3_PWMSAR                0x0C    /* PWM Sample Register */
33 #define MX3_PWMPR                 0x10    /* PWM Period Register */
34 #define MX3_PWMCR_PRESCALER(x)    (((x - 1) & 0xFFF) << 4)
35 #define MX3_PWMCR_DOZEEN                (1 << 24)
36 #define MX3_PWMCR_WAITEN                (1 << 23)
37 #define MX3_PWMCR_DBGEN                 (1 << 22)
38 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
39 #define MX3_PWMCR_CLKSRC_IPG      (1 << 16)
40 #define MX3_PWMCR_EN              (1 << 0)
41
42
43
44 struct pwm_device {
45         struct list_head        node;
46         struct platform_device *pdev;
47
48         const char      *label;
49         struct clk      *clk;
50
51         int             clk_enabled;
52         void __iomem    *mmio_base;
53
54         unsigned int    use_count;
55         unsigned int    pwm_id;
56 };
57
58 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
59 {
60         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
61                 return -EINVAL;
62
63         if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25() || cpu_is_mx51()) {
64                 unsigned long long c;
65                 unsigned long period_cycles, duty_cycles, prescale;
66                 u32 cr;
67
68                 c = clk_get_rate(pwm->clk);
69                 c = c * period_ns;
70                 do_div(c, 1000000000);
71                 period_cycles = c;
72
73                 prescale = period_cycles / 0x10000 + 1;
74
75                 period_cycles /= prescale;
76                 c = (unsigned long long)period_cycles * duty_ns;
77                 do_div(c, period_ns);
78                 duty_cycles = c;
79
80                 /*
81                  * according to imx pwm RM, the real period value should be
82                  * PERIOD value in PWMPR plus 2.
83                  */
84                 if (period_cycles > 2)
85                         period_cycles -= 2;
86                 else
87                         period_cycles = 0;
88
89                 writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
90                 writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
91
92                 cr = MX3_PWMCR_PRESCALER(prescale) |
93                         MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
94                         MX3_PWMCR_DBGEN | MX3_PWMCR_EN;
95
96                 if (cpu_is_mx25())
97                         cr |= MX3_PWMCR_CLKSRC_IPG;
98                 else
99                         cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
100
101                 writel(cr, pwm->mmio_base + MX3_PWMCR);
102         } else if (cpu_is_mx1() || cpu_is_mx21()) {
103                 /* The PWM subsystem allows for exact frequencies. However,
104                  * I cannot connect a scope on my device to the PWM line and
105                  * thus cannot provide the program the PWM controller
106                  * exactly. Instead, I'm relying on the fact that the
107                  * Bootloader (u-boot or WinCE+haret) has programmed the PWM
108                  * function group already. So I'll just modify the PWM sample
109                  * register to follow the ratio of duty_ns vs. period_ns
110                  * accordingly.
111                  *
112                  * This is good enough for programming the brightness of
113                  * the LCD backlight.
114                  *
115                  * The real implementation would divide PERCLK[0] first by
116                  * both the prescaler (/1 .. /128) and then by CLKSEL
117                  * (/2 .. /16).
118                  */
119                 u32 max = readl(pwm->mmio_base + MX1_PWMP);
120                 u32 p = max * duty_ns / period_ns;
121                 writel(max - p, pwm->mmio_base + MX1_PWMS);
122         } else {
123                 BUG();
124         }
125
126         return 0;
127 }
128 EXPORT_SYMBOL(pwm_config);
129
130 int pwm_enable(struct pwm_device *pwm)
131 {
132         int rc = 0;
133
134         if (!pwm->clk_enabled) {
135                 rc = clk_enable(pwm->clk);
136                 if (!rc)
137                         pwm->clk_enabled = 1;
138         }
139         return rc;
140 }
141 EXPORT_SYMBOL(pwm_enable);
142
143 void pwm_disable(struct pwm_device *pwm)
144 {
145         writel(0, pwm->mmio_base + MX3_PWMCR);
146
147         if (pwm->clk_enabled) {
148                 clk_disable(pwm->clk);
149                 pwm->clk_enabled = 0;
150         }
151 }
152 EXPORT_SYMBOL(pwm_disable);
153
154 static DEFINE_MUTEX(pwm_lock);
155 static LIST_HEAD(pwm_list);
156
157 struct pwm_device *pwm_request(int pwm_id, const char *label)
158 {
159         struct pwm_device *pwm;
160         int found = 0;
161
162         mutex_lock(&pwm_lock);
163
164         list_for_each_entry(pwm, &pwm_list, node) {
165                 if (pwm->pwm_id == pwm_id) {
166                         found = 1;
167                         break;
168                 }
169         }
170
171         if (found) {
172                 if (pwm->use_count == 0) {
173                         pwm->use_count++;
174                         pwm->label = label;
175                 } else
176                         pwm = ERR_PTR(-EBUSY);
177         } else
178                 pwm = ERR_PTR(-ENOENT);
179
180         mutex_unlock(&pwm_lock);
181         return pwm;
182 }
183 EXPORT_SYMBOL(pwm_request);
184
185 void pwm_free(struct pwm_device *pwm)
186 {
187         mutex_lock(&pwm_lock);
188
189         if (pwm->use_count) {
190                 pwm->use_count--;
191                 pwm->label = NULL;
192         } else
193                 pr_warning("PWM device already freed\n");
194
195         mutex_unlock(&pwm_lock);
196 }
197 EXPORT_SYMBOL(pwm_free);
198
199 static int __devinit mxc_pwm_probe(struct platform_device *pdev)
200 {
201         struct pwm_device *pwm;
202         struct resource *r;
203         int ret = 0;
204
205         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
206         if (pwm == NULL) {
207                 dev_err(&pdev->dev, "failed to allocate memory\n");
208                 return -ENOMEM;
209         }
210
211         pwm->clk = clk_get(&pdev->dev, "pwm");
212
213         if (IS_ERR(pwm->clk)) {
214                 ret = PTR_ERR(pwm->clk);
215                 goto err_free;
216         }
217
218         pwm->clk_enabled = 0;
219
220         pwm->use_count = 0;
221         pwm->pwm_id = pdev->id;
222         pwm->pdev = pdev;
223
224         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
225         if (r == NULL) {
226                 dev_err(&pdev->dev, "no memory resource defined\n");
227                 ret = -ENODEV;
228                 goto err_free_clk;
229         }
230
231         r = request_mem_region(r->start, resource_size(r), pdev->name);
232         if (r == NULL) {
233                 dev_err(&pdev->dev, "failed to request memory resource\n");
234                 ret = -EBUSY;
235                 goto err_free_clk;
236         }
237
238         pwm->mmio_base = ioremap(r->start, resource_size(r));
239         if (pwm->mmio_base == NULL) {
240                 dev_err(&pdev->dev, "failed to ioremap() registers\n");
241                 ret = -ENODEV;
242                 goto err_free_mem;
243         }
244
245         mutex_lock(&pwm_lock);
246         list_add_tail(&pwm->node, &pwm_list);
247         mutex_unlock(&pwm_lock);
248
249         platform_set_drvdata(pdev, pwm);
250         return 0;
251
252 err_free_mem:
253         release_mem_region(r->start, resource_size(r));
254 err_free_clk:
255         clk_put(pwm->clk);
256 err_free:
257         kfree(pwm);
258         return ret;
259 }
260
261 static int __devexit mxc_pwm_remove(struct platform_device *pdev)
262 {
263         struct pwm_device *pwm;
264         struct resource *r;
265
266         pwm = platform_get_drvdata(pdev);
267         if (pwm == NULL)
268                 return -ENODEV;
269
270         mutex_lock(&pwm_lock);
271         list_del(&pwm->node);
272         mutex_unlock(&pwm_lock);
273
274         iounmap(pwm->mmio_base);
275
276         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
277         release_mem_region(r->start, resource_size(r));
278
279         clk_put(pwm->clk);
280
281         kfree(pwm);
282         return 0;
283 }
284
285 static struct platform_driver mxc_pwm_driver = {
286         .driver         = {
287                 .name   = "mxc_pwm",
288         },
289         .probe          = mxc_pwm_probe,
290         .remove         = __devexit_p(mxc_pwm_remove),
291 };
292
293 static int __init mxc_pwm_init(void)
294 {
295         return platform_driver_register(&mxc_pwm_driver);
296 }
297 arch_initcall(mxc_pwm_init);
298
299 static void __exit mxc_pwm_exit(void)
300 {
301         platform_driver_unregister(&mxc_pwm_driver);
302 }
303 module_exit(mxc_pwm_exit);
304
305 MODULE_LICENSE("GPL v2");
306 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");