1 /*
2 * linux/arch/arm/mach-pxa/pwm.c
3 *
4 * simple driver for PWM (Pulse Width Modulator) controller
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * 2008-02-13 initial version
11 * eric miao <eric.miao@marvell.com>
12 */
13
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/platform_device.h>
17 #include <linux/err.h>
18 #include <linux/clk.h>
19 #include <linux/io.h>
20 #include <linux/pwm.h>
21
22 #include <asm/div64.h>
23
24 #define HAS_SECONDARY_PWM 0x10
25 #define PWM_ID_BASE(d) ((d) & 0xf)
26
27 static const struct platform_device_id pwm_id_table[] = {
28 /* PWM has_secondary_pwm? */
29 { "pxa25x-pwm", 0 },
30 { "pxa27x-pwm", 0 | HAS_SECONDARY_PWM },
31 { "pxa168-pwm", 1 },
32 { "pxa910-pwm", 1 },
33 { },
34 };
35 MODULE_DEVICE_TABLE(platform, pwm_id_table);
36
37 /* PWM registers and bits definitions */
38 #define PWMCR (0x00)
39 #define PWMDCR (0x04)
40 #define PWMPCR (0x08)
41
42 #define PWMCR_SD (1 << 6)
43 #define PWMDCR_FD (1 << 10)
44
45 struct pwm_device {
46 struct list_head node;
47 struct pwm_device *secondary;
48 struct platform_device *pdev;
49
50 const char *label;
51 struct clk *clk;
52 int clk_enabled;
53 void __iomem *mmio_base;
54
55 unsigned int use_count;
56 unsigned int pwm_id;
57 };
58
59 /*
60 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
61 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
62 */
63 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
64 {
65 unsigned long long c;
66 unsigned long period_cycles, prescale, pv, dc;
67
68 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
69 return -EINVAL;
70
71 c = clk_get_rate(pwm->clk);
72 c = c * period_ns;
73 do_div(c, 1000000000);
74 period_cycles = c;
75
76 if (period_cycles < 1)
77 period_cycles = 1;
78 prescale = (period_cycles - 1) / 1024;
79 pv = period_cycles / (prescale + 1) - 1;
80
81 if (prescale > 63)
82 return -EINVAL;
83
84 if (duty_ns == period_ns)
85 dc = PWMDCR_FD;
86 else
87 dc = (pv + 1) * duty_ns / period_ns;
88
89 /* NOTE: the clock to PWM has to be enabled first
90 * before writing to the registers
91 */
92 clk_enable(pwm->clk);
93 __raw_writel(prescale, pwm->mmio_base + PWMCR);
94 __raw_writel(dc, pwm->mmio_base + PWMDCR);
95 __raw_writel(pv, pwm->mmio_base + PWMPCR);
96 clk_disable(pwm->clk);
97
98 return 0;
99 }
100 EXPORT_SYMBOL(pwm_config);
101
102 int pwm_enable(struct pwm_device *pwm)
103 {
104 int rc = 0;
105
106 if (!pwm->clk_enabled) {
107 rc = clk_enable(pwm->clk);
108 if (!rc)
109 pwm->clk_enabled = 1;
110 }
111 return rc;
112 }
113 EXPORT_SYMBOL(pwm_enable);
114
115 void pwm_disable(struct pwm_device *pwm)
116 {
117 if (pwm->clk_enabled) {
118 clk_disable(pwm->clk);
119 pwm->clk_enabled = 0;
120 }
121 }
122 EXPORT_SYMBOL(pwm_disable);
123
124 static DEFINE_MUTEX(pwm_lock);
125 static LIST_HEAD(pwm_list);
126
127 struct pwm_device *pwm_request(int pwm_id, const char *label)
128 {
129 struct pwm_device *pwm;
130 int found = 0;
131
132 mutex_lock(&pwm_lock);
133
134 list_for_each_entry(pwm, &pwm_list, node) {
135 if (pwm->pwm_id == pwm_id) {
136 found = 1;
137 break;
138 }
139 }
140
141 if (found) {
142 if (pwm->use_count == 0) {
143 pwm->use_count++;
144 pwm->label = label;
145 } else
146 pwm = ERR_PTR(-EBUSY);
147 } else
148 pwm = ERR_PTR(-ENOENT);
149
150 mutex_unlock(&pwm_lock);
151 return pwm;
152 }
153 EXPORT_SYMBOL(pwm_request);
154
155 void pwm_free(struct pwm_device *pwm)
156 {
157 mutex_lock(&pwm_lock);
158
159 if (pwm->use_count) {
160 pwm->use_count--;
161 pwm->label = NULL;
162 } else
163 pr_warning("PWM device already freed\n");
164
165 mutex_unlock(&pwm_lock);
166 }
167 EXPORT_SYMBOL(pwm_free);
168
169 static inline void __add_pwm(struct pwm_device *pwm)
170 {
171 mutex_lock(&pwm_lock);
172 list_add_tail(&pwm->node, &pwm_list);
173 mutex_unlock(&pwm_lock);
174 }
175
176 static int __devinit pwm_probe(struct platform_device *pdev)
177 {
178 struct platform_device_id *id = platform_get_device_id(pdev);
179 struct pwm_device *pwm, *secondary = NULL;
180 struct resource *r;
181 int ret = 0;
182
183 pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
184 if (pwm == NULL) {
185 dev_err(&pdev->dev, "failed to allocate memory\n");
186 return -ENOMEM;
187 }
188
189 pwm->clk = clk_get(&pdev->dev, NULL);
190 if (IS_ERR(pwm->clk)) {
191 ret = PTR_ERR(pwm->clk);
192 goto err_free;
193 }
194 pwm->clk_enabled = 0;
195
196 pwm->use_count = 0;
197 pwm->pwm_id = PWM_ID_BASE(id->driver_data) + pdev->id;
198 pwm->pdev = pdev;
199
200 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
201 if (r == NULL) {
202 dev_err(&pdev->dev, "no memory resource defined\n");
203 ret = -ENODEV;
204 goto err_free_clk;
205 }
206
207 r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
208 if (r == NULL) {
209 dev_err(&pdev->dev, "failed to request memory resource\n");
210 ret = -EBUSY;
211 goto err_free_clk;
212 }
213
214 pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
215 if (pwm->mmio_base == NULL) {
216 dev_err(&pdev->dev, "failed to ioremap() registers\n");
217 ret = -ENODEV;
218 goto err_free_mem;
219 }
220
221 if (id->driver_data & HAS_SECONDARY_PWM) {
222 secondary = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
223 if (secondary == NULL) {
224 ret = -ENOMEM;
225 goto err_free_mem;
226 }
227
228 *secondary = *pwm;
229 pwm->secondary = secondary;
230
231 /* registers for the second PWM has offset of 0x10 */
232 secondary->mmio_base = pwm->mmio_base + 0x10;
233 secondary->pwm_id = pdev->id + 2;
234 }
235
236 __add_pwm(pwm);
237 if (secondary)
238 __add_pwm(secondary);
239
240 platform_set_drvdata(pdev, pwm);
241 return 0;
242
243 err_free_mem:
244 release_mem_region(r->start, r->end - r->start + 1);
245 err_free_clk:
246 clk_put(pwm->clk);
247 err_free:
248 kfree(pwm);
249 return ret;
250 }
251
252 static int __devexit pwm_remove(struct platform_device *pdev)
253 {
254 struct pwm_device *pwm;
255 struct resource *r;
256
257 pwm = platform_get_drvdata(pdev);
258 if (pwm == NULL)
259 return -ENODEV;
260
261 mutex_lock(&pwm_lock);
262
263 if (pwm->secondary) {
264 list_del(&pwm->secondary->node);
265 kfree(pwm->secondary);
266 }
267
268 list_del(&pwm->node);
269 mutex_unlock(&pwm_lock);
270
271 iounmap(pwm->mmio_base);
272
273 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
274 release_mem_region(r->start, r->end - r->start + 1);
275
276 clk_put(pwm->clk);
277 kfree(pwm);
278 return 0;
279 }
280
281 static struct platform_driver pwm_driver = {
282 .driver = {
283 .name = "pxa25x-pwm",
284 .owner = THIS_MODULE,
285 },
286 .probe = pwm_probe,
287 .remove = __devexit_p(pwm_remove),
288 .id_table = pwm_id_table,
289 };
290
291 static int __init pwm_init(void)
292 {
293 return platform_driver_register(&pwm_driver);
294 }
295 arch_initcall(pwm_init);
296
297 static void __exit pwm_exit(void)
298 {
299 platform_driver_unregister(&pwm_driver);
300 }
301 module_exit(pwm_exit);
302
303 MODULE_LICENSE("GPL v2");
304
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