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