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21f47fbc AC |
1 | /* |
2 | * arch/arm/mach-vt8500/pwm.c | |
3 | * | |
4 | * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com> | |
5 | * | |
6 | * This software is licensed under the terms of the GNU General Public | |
7 | * License version 2, as published by the Free Software Foundation, and | |
8 | * may be copied, distributed, and modified under those terms. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | */ | |
15 | ||
16 | #include <linux/module.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/platform_device.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/err.h> | |
21 | #include <linux/io.h> | |
22 | #include <linux/pwm.h> | |
23 | #include <linux/delay.h> | |
24 | ||
25 | #include <asm/div64.h> | |
26 | ||
27 | #define VT8500_NR_PWMS 4 | |
28 | ||
a245cceb SH |
29 | struct vt8500_chip { |
30 | struct pwm_chip chip; | |
31 | void __iomem *base; | |
21f47fbc AC |
32 | }; |
33 | ||
a245cceb SH |
34 | #define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip) |
35 | ||
21f47fbc AC |
36 | #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) |
37 | static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask) | |
38 | { | |
39 | int loops = msecs_to_loops(10); | |
40 | while ((readb(reg) & bitmask) && --loops) | |
41 | cpu_relax(); | |
42 | ||
43 | if (unlikely(!loops)) | |
44 | pr_warning("Waiting for status bits 0x%x to clear timed out\n", | |
45 | bitmask); | |
46 | } | |
47 | ||
a245cceb SH |
48 | static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, |
49 | int duty_ns, int period_ns) | |
21f47fbc | 50 | { |
a245cceb | 51 | struct vt8500_chip *vt8500 = to_vt8500_chip(chip); |
21f47fbc AC |
52 | unsigned long long c; |
53 | unsigned long period_cycles, prescale, pv, dc; | |
54 | ||
21f47fbc AC |
55 | c = 25000000/2; /* wild guess --- need to implement clocks */ |
56 | c = c * period_ns; | |
57 | do_div(c, 1000000000); | |
58 | period_cycles = c; | |
59 | ||
60 | if (period_cycles < 1) | |
61 | period_cycles = 1; | |
62 | prescale = (period_cycles - 1) / 4096; | |
63 | pv = period_cycles / (prescale + 1) - 1; | |
64 | if (pv > 4095) | |
65 | pv = 4095; | |
66 | ||
67 | if (prescale > 1023) | |
68 | return -EINVAL; | |
69 | ||
70 | c = (unsigned long long)pv * duty_ns; | |
71 | do_div(c, period_ns); | |
72 | dc = c; | |
73 | ||
a245cceb SH |
74 | pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 1)); |
75 | writel(prescale, vt8500->base + 0x4 + (pwm->hwpwm << 4)); | |
21f47fbc | 76 | |
a245cceb SH |
77 | pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 2)); |
78 | writel(pv, vt8500->base + 0x8 + (pwm->hwpwm << 4)); | |
21f47fbc | 79 | |
a245cceb SH |
80 | pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 3)); |
81 | writel(dc, vt8500->base + 0xc + (pwm->hwpwm << 4)); | |
21f47fbc AC |
82 | |
83 | return 0; | |
84 | } | |
21f47fbc | 85 | |
a245cceb | 86 | static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) |
21f47fbc | 87 | { |
a245cceb | 88 | struct vt8500_chip *vt8500 = to_vt8500_chip(chip); |
21f47fbc | 89 | |
a245cceb SH |
90 | pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0)); |
91 | writel(5, vt8500->base + (pwm->hwpwm << 4)); | |
92 | return 0; | |
21f47fbc | 93 | } |
21f47fbc | 94 | |
a245cceb | 95 | static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) |
21f47fbc | 96 | { |
a245cceb | 97 | struct vt8500_chip *vt8500 = to_vt8500_chip(chip); |
21f47fbc | 98 | |
a245cceb SH |
99 | pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0)); |
100 | writel(0, vt8500->base + (pwm->hwpwm << 4)); | |
21f47fbc | 101 | } |
21f47fbc | 102 | |
a245cceb SH |
103 | static struct pwm_ops vt8500_pwm_ops = { |
104 | .enable = vt8500_pwm_enable, | |
105 | .disable = vt8500_pwm_disable, | |
106 | .config = vt8500_pwm_config, | |
107 | .owner = THIS_MODULE, | |
108 | }; | |
21f47fbc AC |
109 | |
110 | static int __devinit pwm_probe(struct platform_device *pdev) | |
111 | { | |
a245cceb | 112 | struct vt8500_chip *chip; |
21f47fbc | 113 | struct resource *r; |
a245cceb | 114 | int ret; |
21f47fbc | 115 | |
a245cceb SH |
116 | chip = kzalloc(sizeof(*chip), GFP_KERNEL); |
117 | if (chip == NULL) { | |
21f47fbc AC |
118 | dev_err(&pdev->dev, "failed to allocate memory\n"); |
119 | return -ENOMEM; | |
120 | } | |
121 | ||
a245cceb SH |
122 | chip->chip.dev = &pdev->dev; |
123 | chip->chip.ops = &vt8500_pwm_ops; | |
124 | chip->chip.base = -1; | |
125 | chip->chip.npwm = VT8500_NR_PWMS; | |
21f47fbc AC |
126 | |
127 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
128 | if (r == NULL) { | |
129 | dev_err(&pdev->dev, "no memory resource defined\n"); | |
130 | ret = -ENODEV; | |
131 | goto err_free; | |
132 | } | |
133 | ||
134 | r = request_mem_region(r->start, resource_size(r), pdev->name); | |
135 | if (r == NULL) { | |
136 | dev_err(&pdev->dev, "failed to request memory resource\n"); | |
137 | ret = -EBUSY; | |
138 | goto err_free; | |
139 | } | |
140 | ||
a245cceb SH |
141 | chip->base = ioremap(r->start, resource_size(r)); |
142 | if (chip->base == NULL) { | |
21f47fbc AC |
143 | dev_err(&pdev->dev, "failed to ioremap() registers\n"); |
144 | ret = -ENODEV; | |
145 | goto err_free_mem; | |
146 | } | |
147 | ||
a245cceb SH |
148 | ret = pwmchip_add(&chip->chip); |
149 | if (ret < 0) | |
150 | goto err_unmap; | |
21f47fbc | 151 | |
a245cceb SH |
152 | platform_set_drvdata(pdev, chip); |
153 | return ret; | |
21f47fbc | 154 | |
a245cceb SH |
155 | err_unmap: |
156 | iounmap(chip->base); | |
21f47fbc AC |
157 | err_free_mem: |
158 | release_mem_region(r->start, resource_size(r)); | |
159 | err_free: | |
a245cceb | 160 | kfree(chip); |
21f47fbc AC |
161 | return ret; |
162 | } | |
163 | ||
164 | static int __devexit pwm_remove(struct platform_device *pdev) | |
165 | { | |
a245cceb | 166 | struct vt8500_chip *chip; |
21f47fbc | 167 | struct resource *r; |
a245cceb | 168 | int err; |
21f47fbc | 169 | |
a245cceb SH |
170 | chip = platform_get_drvdata(pdev); |
171 | if (chip == NULL) | |
21f47fbc AC |
172 | return -ENODEV; |
173 | ||
a245cceb SH |
174 | err = pwmchip_remove(&chip->chip); |
175 | if (err < 0) | |
176 | return err; | |
21f47fbc | 177 | |
a245cceb | 178 | iounmap(chip->base); |
21f47fbc AC |
179 | |
180 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
181 | release_mem_region(r->start, resource_size(r)); | |
182 | ||
a245cceb | 183 | kfree(chip); |
21f47fbc AC |
184 | return 0; |
185 | } | |
186 | ||
187 | static struct platform_driver pwm_driver = { | |
188 | .driver = { | |
189 | .name = "vt8500-pwm", | |
190 | .owner = THIS_MODULE, | |
191 | }, | |
192 | .probe = pwm_probe, | |
193 | .remove = __devexit_p(pwm_remove), | |
194 | }; | |
195 | ||
196 | static int __init pwm_init(void) | |
197 | { | |
198 | return platform_driver_register(&pwm_driver); | |
199 | } | |
200 | arch_initcall(pwm_init); | |
201 | ||
202 | static void __exit pwm_exit(void) | |
203 | { | |
204 | platform_driver_unregister(&pwm_driver); | |
205 | } | |
206 | module_exit(pwm_exit); | |
207 | ||
208 | MODULE_LICENSE("GPL"); |