]>
Commit | Line | Data |
---|---|---|
166091b1 SH |
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> | |
5a0e3ad6 | 14 | #include <linux/slab.h> |
166091b1 SH |
15 | #include <linux/err.h> |
16 | #include <linux/clk.h> | |
17 | #include <linux/io.h> | |
18 | #include <linux/pwm.h> | |
c010dba8 HS |
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_CLKSRC_IPG_HIGH (2 << 16) | |
a058cbc1 | 36 | #define MX3_PWMCR_CLKSRC_IPG (1 << 16) |
c010dba8 HS |
37 | #define MX3_PWMCR_EN (1 << 0) |
38 | ||
166091b1 | 39 | |
166091b1 SH |
40 | |
41 | struct pwm_device { | |
42 | struct list_head node; | |
43 | struct platform_device *pdev; | |
44 | ||
45 | const char *label; | |
46 | struct clk *clk; | |
47 | ||
48 | int clk_enabled; | |
49 | void __iomem *mmio_base; | |
50 | ||
51 | unsigned int use_count; | |
52 | unsigned int pwm_id; | |
53 | }; | |
54 | ||
55 | int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) | |
56 | { | |
166091b1 SH |
57 | if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) |
58 | return -EINVAL; | |
59 | ||
dd027b00 | 60 | if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25() || cpu_is_mx51()) { |
c010dba8 HS |
61 | unsigned long long c; |
62 | unsigned long period_cycles, duty_cycles, prescale; | |
a058cbc1 SH |
63 | u32 cr; |
64 | ||
c010dba8 HS |
65 | c = clk_get_rate(pwm->clk); |
66 | c = c * period_ns; | |
67 | do_div(c, 1000000000); | |
68 | period_cycles = c; | |
69 | ||
70 | prescale = period_cycles / 0x10000 + 1; | |
71 | ||
72 | period_cycles /= prescale; | |
73 | c = (unsigned long long)period_cycles * duty_ns; | |
74 | do_div(c, period_ns); | |
75 | duty_cycles = c; | |
76 | ||
77 | writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR); | |
78 | writel(period_cycles, pwm->mmio_base + MX3_PWMPR); | |
a058cbc1 SH |
79 | |
80 | cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN; | |
81 | ||
82 | if (cpu_is_mx25()) | |
83 | cr |= MX3_PWMCR_CLKSRC_IPG; | |
84 | else | |
85 | cr |= MX3_PWMCR_CLKSRC_IPG_HIGH; | |
86 | ||
87 | writel(cr, pwm->mmio_base + MX3_PWMCR); | |
c010dba8 HS |
88 | } else if (cpu_is_mx1() || cpu_is_mx21()) { |
89 | /* The PWM subsystem allows for exact frequencies. However, | |
90 | * I cannot connect a scope on my device to the PWM line and | |
91 | * thus cannot provide the program the PWM controller | |
92 | * exactly. Instead, I'm relying on the fact that the | |
93 | * Bootloader (u-boot or WinCE+haret) has programmed the PWM | |
94 | * function group already. So I'll just modify the PWM sample | |
95 | * register to follow the ratio of duty_ns vs. period_ns | |
96 | * accordingly. | |
97 | * | |
af901ca1 | 98 | * This is good enough for programming the brightness of |
c010dba8 HS |
99 | * the LCD backlight. |
100 | * | |
101 | * The real implementation would divide PERCLK[0] first by | |
102 | * both the prescaler (/1 .. /128) and then by CLKSEL | |
103 | * (/2 .. /16). | |
104 | */ | |
105 | u32 max = readl(pwm->mmio_base + MX1_PWMP); | |
106 | u32 p = max * duty_ns / period_ns; | |
107 | writel(max - p, pwm->mmio_base + MX1_PWMS); | |
108 | } else { | |
109 | BUG(); | |
110 | } | |
166091b1 SH |
111 | |
112 | return 0; | |
113 | } | |
114 | EXPORT_SYMBOL(pwm_config); | |
115 | ||
116 | int pwm_enable(struct pwm_device *pwm) | |
117 | { | |
118 | int rc = 0; | |
119 | ||
120 | if (!pwm->clk_enabled) { | |
121 | rc = clk_enable(pwm->clk); | |
122 | if (!rc) | |
123 | pwm->clk_enabled = 1; | |
124 | } | |
125 | return rc; | |
126 | } | |
127 | EXPORT_SYMBOL(pwm_enable); | |
128 | ||
129 | void pwm_disable(struct pwm_device *pwm) | |
130 | { | |
5ef881bb SH |
131 | writel(0, pwm->mmio_base + MX3_PWMCR); |
132 | ||
166091b1 SH |
133 | if (pwm->clk_enabled) { |
134 | clk_disable(pwm->clk); | |
135 | pwm->clk_enabled = 0; | |
136 | } | |
137 | } | |
138 | EXPORT_SYMBOL(pwm_disable); | |
139 | ||
140 | static DEFINE_MUTEX(pwm_lock); | |
141 | static LIST_HEAD(pwm_list); | |
142 | ||
143 | struct pwm_device *pwm_request(int pwm_id, const char *label) | |
144 | { | |
145 | struct pwm_device *pwm; | |
146 | int found = 0; | |
147 | ||
148 | mutex_lock(&pwm_lock); | |
149 | ||
150 | list_for_each_entry(pwm, &pwm_list, node) { | |
151 | if (pwm->pwm_id == pwm_id) { | |
152 | found = 1; | |
153 | break; | |
154 | } | |
155 | } | |
156 | ||
157 | if (found) { | |
158 | if (pwm->use_count == 0) { | |
159 | pwm->use_count++; | |
160 | pwm->label = label; | |
161 | } else | |
162 | pwm = ERR_PTR(-EBUSY); | |
163 | } else | |
164 | pwm = ERR_PTR(-ENOENT); | |
165 | ||
166 | mutex_unlock(&pwm_lock); | |
167 | return pwm; | |
168 | } | |
169 | EXPORT_SYMBOL(pwm_request); | |
170 | ||
171 | void pwm_free(struct pwm_device *pwm) | |
172 | { | |
173 | mutex_lock(&pwm_lock); | |
174 | ||
175 | if (pwm->use_count) { | |
176 | pwm->use_count--; | |
177 | pwm->label = NULL; | |
178 | } else | |
179 | pr_warning("PWM device already freed\n"); | |
180 | ||
181 | mutex_unlock(&pwm_lock); | |
182 | } | |
183 | EXPORT_SYMBOL(pwm_free); | |
184 | ||
185 | static int __devinit mxc_pwm_probe(struct platform_device *pdev) | |
186 | { | |
187 | struct pwm_device *pwm; | |
188 | struct resource *r; | |
189 | int ret = 0; | |
190 | ||
191 | pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL); | |
192 | if (pwm == NULL) { | |
193 | dev_err(&pdev->dev, "failed to allocate memory\n"); | |
194 | return -ENOMEM; | |
195 | } | |
196 | ||
197 | pwm->clk = clk_get(&pdev->dev, "pwm"); | |
198 | ||
199 | if (IS_ERR(pwm->clk)) { | |
200 | ret = PTR_ERR(pwm->clk); | |
201 | goto err_free; | |
202 | } | |
203 | ||
204 | pwm->clk_enabled = 0; | |
205 | ||
206 | pwm->use_count = 0; | |
207 | pwm->pwm_id = pdev->id; | |
208 | pwm->pdev = pdev; | |
209 | ||
210 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
211 | if (r == NULL) { | |
212 | dev_err(&pdev->dev, "no memory resource defined\n"); | |
213 | ret = -ENODEV; | |
214 | goto err_free_clk; | |
215 | } | |
216 | ||
28f65c11 | 217 | r = request_mem_region(r->start, resource_size(r), pdev->name); |
166091b1 SH |
218 | if (r == NULL) { |
219 | dev_err(&pdev->dev, "failed to request memory resource\n"); | |
220 | ret = -EBUSY; | |
221 | goto err_free_clk; | |
222 | } | |
223 | ||
28f65c11 | 224 | pwm->mmio_base = ioremap(r->start, resource_size(r)); |
166091b1 SH |
225 | if (pwm->mmio_base == NULL) { |
226 | dev_err(&pdev->dev, "failed to ioremap() registers\n"); | |
227 | ret = -ENODEV; | |
228 | goto err_free_mem; | |
229 | } | |
230 | ||
231 | mutex_lock(&pwm_lock); | |
232 | list_add_tail(&pwm->node, &pwm_list); | |
233 | mutex_unlock(&pwm_lock); | |
234 | ||
235 | platform_set_drvdata(pdev, pwm); | |
236 | return 0; | |
237 | ||
238 | err_free_mem: | |
28f65c11 | 239 | release_mem_region(r->start, resource_size(r)); |
166091b1 SH |
240 | err_free_clk: |
241 | clk_put(pwm->clk); | |
242 | err_free: | |
243 | kfree(pwm); | |
244 | return ret; | |
245 | } | |
246 | ||
247 | static int __devexit mxc_pwm_remove(struct platform_device *pdev) | |
248 | { | |
249 | struct pwm_device *pwm; | |
250 | struct resource *r; | |
251 | ||
252 | pwm = platform_get_drvdata(pdev); | |
253 | if (pwm == NULL) | |
254 | return -ENODEV; | |
255 | ||
256 | mutex_lock(&pwm_lock); | |
257 | list_del(&pwm->node); | |
258 | mutex_unlock(&pwm_lock); | |
259 | ||
260 | iounmap(pwm->mmio_base); | |
261 | ||
262 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
28f65c11 | 263 | release_mem_region(r->start, resource_size(r)); |
166091b1 SH |
264 | |
265 | clk_put(pwm->clk); | |
266 | ||
267 | kfree(pwm); | |
268 | return 0; | |
269 | } | |
270 | ||
271 | static struct platform_driver mxc_pwm_driver = { | |
272 | .driver = { | |
273 | .name = "mxc_pwm", | |
274 | }, | |
275 | .probe = mxc_pwm_probe, | |
276 | .remove = __devexit_p(mxc_pwm_remove), | |
277 | }; | |
278 | ||
279 | static int __init mxc_pwm_init(void) | |
280 | { | |
281 | return platform_driver_register(&mxc_pwm_driver); | |
282 | } | |
283 | arch_initcall(mxc_pwm_init); | |
284 | ||
285 | static void __exit mxc_pwm_exit(void) | |
286 | { | |
287 | platform_driver_unregister(&mxc_pwm_driver); | |
288 | } | |
289 | module_exit(mxc_pwm_exit); | |
290 | ||
291 | MODULE_LICENSE("GPL v2"); | |
292 | MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); |