2 * arch/arm/mach-vt8500/pwm.c
4 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
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.
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.
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>
22 #include <linux/pwm.h>
23 #include <linux/delay.h>
25 #include <asm/div64.h>
27 #define VT8500_NR_PWMS 4
34 #define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip)
36 #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
37 static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask)
39 int loops = msecs_to_loops(10);
40 while ((readb(reg) & bitmask) && --loops)
44 pr_warning("Waiting for status bits 0x%x to clear timed out\n",
48 static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
49 int duty_ns, int period_ns)
51 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
53 unsigned long period_cycles, prescale, pv, dc;
55 c = 25000000/2; /* wild guess --- need to implement clocks */
57 do_div(c, 1000000000);
60 if (period_cycles < 1)
62 prescale = (period_cycles - 1) / 4096;
63 pv = period_cycles / (prescale + 1) - 1;
70 c = (unsigned long long)pv * duty_ns;
74 pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 1));
75 writel(prescale, vt8500->base + 0x4 + (pwm->hwpwm << 4));
77 pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 2));
78 writel(pv, vt8500->base + 0x8 + (pwm->hwpwm << 4));
80 pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 3));
81 writel(dc, vt8500->base + 0xc + (pwm->hwpwm << 4));
86 static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
88 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
90 pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
91 writel(5, vt8500->base + (pwm->hwpwm << 4));
95 static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
97 struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
99 pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
100 writel(0, vt8500->base + (pwm->hwpwm << 4));
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,
110 static int __devinit pwm_probe(struct platform_device *pdev)
112 struct vt8500_chip *chip;
116 chip = kzalloc(sizeof(*chip), GFP_KERNEL);
118 dev_err(&pdev->dev, "failed to allocate memory\n");
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;
127 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
129 dev_err(&pdev->dev, "no memory resource defined\n");
134 r = request_mem_region(r->start, resource_size(r), pdev->name);
136 dev_err(&pdev->dev, "failed to request memory resource\n");
141 chip->base = ioremap(r->start, resource_size(r));
142 if (chip->base == NULL) {
143 dev_err(&pdev->dev, "failed to ioremap() registers\n");
148 ret = pwmchip_add(&chip->chip);
152 platform_set_drvdata(pdev, chip);
158 release_mem_region(r->start, resource_size(r));
164 static int __devexit pwm_remove(struct platform_device *pdev)
166 struct vt8500_chip *chip;
170 chip = platform_get_drvdata(pdev);
174 err = pwmchip_remove(&chip->chip);
180 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
181 release_mem_region(r->start, resource_size(r));
187 static struct platform_driver pwm_driver = {
189 .name = "vt8500-pwm",
190 .owner = THIS_MODULE,
193 .remove = __devexit_p(pwm_remove),
196 static int __init pwm_init(void)
198 return platform_driver_register(&pwm_driver);
200 arch_initcall(pwm_init);
202 static void __exit pwm_exit(void)
204 platform_driver_unregister(&pwm_driver);
206 module_exit(pwm_exit);
208 MODULE_LICENSE("GPL");