Merge branch for-rmk-devel of git://aeryn.fluff.org.uk/bjdooks/linux into devel
[linux-2.6] / 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_EN              (1 << 0)
36
37
38
39 struct pwm_device {
40         struct list_head        node;
41         struct platform_device *pdev;
42
43         const char      *label;
44         struct clk      *clk;
45
46         int             clk_enabled;
47         void __iomem    *mmio_base;
48
49         unsigned int    use_count;
50         unsigned int    pwm_id;
51 };
52
53 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
54 {
55         if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
56                 return -EINVAL;
57
58         if (cpu_is_mx27() || cpu_is_mx3()) {
59                 unsigned long long c;
60                 unsigned long period_cycles, duty_cycles, prescale;
61                 c = clk_get_rate(pwm->clk);
62                 c = c * period_ns;
63                 do_div(c, 1000000000);
64                 period_cycles = c;
65
66                 prescale = period_cycles / 0x10000 + 1;
67
68                 period_cycles /= prescale;
69                 c = (unsigned long long)period_cycles * duty_ns;
70                 do_div(c, period_ns);
71                 duty_cycles = c;
72
73                 writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
74                 writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
75                 writel(MX3_PWMCR_PRESCALER(prescale - 1) |
76                         MX3_PWMCR_CLKSRC_IPG_HIGH | MX3_PWMCR_EN,
77                         pwm->mmio_base + MX3_PWMCR);
78         } else if (cpu_is_mx1() || cpu_is_mx21()) {
79                 /* The PWM subsystem allows for exact frequencies. However,
80                  * I cannot connect a scope on my device to the PWM line and
81                  * thus cannot provide the program the PWM controller
82                  * exactly. Instead, I'm relying on the fact that the
83                  * Bootloader (u-boot or WinCE+haret) has programmed the PWM
84                  * function group already. So I'll just modify the PWM sample
85                  * register to follow the ratio of duty_ns vs. period_ns
86                  * accordingly.
87                  *
88                  * This is good enought for programming the brightness of
89                  * the LCD backlight.
90                  *
91                  * The real implementation would divide PERCLK[0] first by
92                  * both the prescaler (/1 .. /128) and then by CLKSEL
93                  * (/2 .. /16).
94                  */
95                 u32 max = readl(pwm->mmio_base + MX1_PWMP);
96                 u32 p = max * duty_ns / period_ns;
97                 writel(max - p, pwm->mmio_base + MX1_PWMS);
98         } else {
99                 BUG();
100         }
101
102         return 0;
103 }
104 EXPORT_SYMBOL(pwm_config);
105
106 int pwm_enable(struct pwm_device *pwm)
107 {
108         int rc = 0;
109
110         if (!pwm->clk_enabled) {
111                 rc = clk_enable(pwm->clk);
112                 if (!rc)
113                         pwm->clk_enabled = 1;
114         }
115         return rc;
116 }
117 EXPORT_SYMBOL(pwm_enable);
118
119 void pwm_disable(struct pwm_device *pwm)
120 {
121         if (pwm->clk_enabled) {
122                 clk_disable(pwm->clk);
123                 pwm->clk_enabled = 0;
124         }
125 }
126 EXPORT_SYMBOL(pwm_disable);
127
128 static DEFINE_MUTEX(pwm_lock);
129 static LIST_HEAD(pwm_list);
130
131 struct pwm_device *pwm_request(int pwm_id, const char *label)
132 {
133         struct pwm_device *pwm;
134         int found = 0;
135
136         mutex_lock(&pwm_lock);
137
138         list_for_each_entry(pwm, &pwm_list, node) {
139                 if (pwm->pwm_id == pwm_id) {
140                         found = 1;
141                         break;
142                 }
143         }
144
145         if (found) {
146                 if (pwm->use_count == 0) {
147                         pwm->use_count++;
148                         pwm->label = label;
149                 } else
150                         pwm = ERR_PTR(-EBUSY);
151         } else
152                 pwm = ERR_PTR(-ENOENT);
153
154         mutex_unlock(&pwm_lock);
155         return pwm;
156 }
157 EXPORT_SYMBOL(pwm_request);
158
159 void pwm_free(struct pwm_device *pwm)
160 {
161         mutex_lock(&pwm_lock);
162
163         if (pwm->use_count) {
164                 pwm->use_count--;
165                 pwm->label = NULL;
166         } else
167                 pr_warning("PWM device already freed\n");
168
169         mutex_unlock(&pwm_lock);
170 }
171 EXPORT_SYMBOL(pwm_free);
172
173 static int __devinit mxc_pwm_probe(struct platform_device *pdev)
174 {
175         struct pwm_device *pwm;
176         struct resource *r;
177         int ret = 0;
178
179         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
180         if (pwm == NULL) {
181                 dev_err(&pdev->dev, "failed to allocate memory\n");
182                 return -ENOMEM;
183         }
184
185         pwm->clk = clk_get(&pdev->dev, "pwm");
186
187         if (IS_ERR(pwm->clk)) {
188                 ret = PTR_ERR(pwm->clk);
189                 goto err_free;
190         }
191
192         pwm->clk_enabled = 0;
193
194         pwm->use_count = 0;
195         pwm->pwm_id = pdev->id;
196         pwm->pdev = pdev;
197
198         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
199         if (r == NULL) {
200                 dev_err(&pdev->dev, "no memory resource defined\n");
201                 ret = -ENODEV;
202                 goto err_free_clk;
203         }
204
205         r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
206         if (r == NULL) {
207                 dev_err(&pdev->dev, "failed to request memory resource\n");
208                 ret = -EBUSY;
209                 goto err_free_clk;
210         }
211
212         pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
213         if (pwm->mmio_base == NULL) {
214                 dev_err(&pdev->dev, "failed to ioremap() registers\n");
215                 ret = -ENODEV;
216                 goto err_free_mem;
217         }
218
219         mutex_lock(&pwm_lock);
220         list_add_tail(&pwm->node, &pwm_list);
221         mutex_unlock(&pwm_lock);
222
223         platform_set_drvdata(pdev, pwm);
224         return 0;
225
226 err_free_mem:
227         release_mem_region(r->start, r->end - r->start + 1);
228 err_free_clk:
229         clk_put(pwm->clk);
230 err_free:
231         kfree(pwm);
232         return ret;
233 }
234
235 static int __devexit mxc_pwm_remove(struct platform_device *pdev)
236 {
237         struct pwm_device *pwm;
238         struct resource *r;
239
240         pwm = platform_get_drvdata(pdev);
241         if (pwm == NULL)
242                 return -ENODEV;
243
244         mutex_lock(&pwm_lock);
245         list_del(&pwm->node);
246         mutex_unlock(&pwm_lock);
247
248         iounmap(pwm->mmio_base);
249
250         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
251         release_mem_region(r->start, r->end - r->start + 1);
252
253         clk_put(pwm->clk);
254
255         kfree(pwm);
256         return 0;
257 }
258
259 static struct platform_driver mxc_pwm_driver = {
260         .driver         = {
261                 .name   = "mxc_pwm",
262         },
263         .probe          = mxc_pwm_probe,
264         .remove         = __devexit_p(mxc_pwm_remove),
265 };
266
267 static int __init mxc_pwm_init(void)
268 {
269         return platform_driver_register(&mxc_pwm_driver);
270 }
271 arch_initcall(mxc_pwm_init);
272
273 static void __exit mxc_pwm_exit(void)
274 {
275         platform_driver_unregister(&mxc_pwm_driver);
276 }
277 module_exit(mxc_pwm_exit);
278
279 MODULE_LICENSE("GPL v2");
280 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");