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/*
* drivers/pwm/pwm-vt8500.c
*
* Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <linux/delay.h>
#include <asm/div64.h>
#define VT8500_NR_PWMS 4
struct vt8500_chip {
struct pwm_chip chip;
void __iomem *base;
};
#define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip)
#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask)
{
int loops = msecs_to_loops(10);
while ((readb(reg) & bitmask) && --loops)
cpu_relax();
if (unlikely(!loops))
pr_warning("Waiting for status bits 0x%x to clear timed out\n",
bitmask);
}
static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
unsigned long long c;
unsigned long period_cycles, prescale, pv, dc;
c = 25000000/2; /* wild guess --- need to implement clocks */
c = c * period_ns;
do_div(c, 1000000000);
period_cycles = c;
if (period_cycles < 1)
period_cycles = 1;
prescale = (period_cycles - 1) / 4096;
pv = period_cycles / (prescale + 1) - 1;
if (pv > 4095)
pv = 4095;
if (prescale > 1023)
return -EINVAL;
c = (unsigned long long)pv * duty_ns;
do_div(c, period_ns);
dc = c;
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 1));
writel(prescale, vt8500->base + 0x4 + (pwm->hwpwm << 4));
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 2));
writel(pv, vt8500->base + 0x8 + (pwm->hwpwm << 4));
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 3));
writel(dc, vt8500->base + 0xc + (pwm->hwpwm << 4));
return 0;
}
static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
writel(5, vt8500->base + (pwm->hwpwm << 4));
return 0;
}
static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
writel(0, vt8500->base + (pwm->hwpwm << 4));
}
static struct pwm_ops vt8500_pwm_ops = {
.enable = vt8500_pwm_enable,
.disable = vt8500_pwm_disable,
.config = vt8500_pwm_config,
.owner = THIS_MODULE,
};
static int __devinit pwm_probe(struct platform_device *pdev)
{
struct vt8500_chip *chip;
struct resource *r;
int ret;
chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
if (chip == NULL) {
dev_err(&pdev->dev, "failed to allocate memory\n");
return -ENOMEM;
}
chip->chip.dev = &pdev->dev;
chip->chip.ops = &vt8500_pwm_ops;
chip->chip.base = -1;
chip->chip.npwm = VT8500_NR_PWMS;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (r == NULL) {
dev_err(&pdev->dev, "no memory resource defined\n");
return -ENODEV;
}
chip->base = devm_request_and_ioremap(&pdev->dev, r);
if (chip->base == NULL)
return -EADDRNOTAVAIL;
ret = pwmchip_add(&chip->chip);
if (ret < 0)
return ret;
platform_set_drvdata(pdev, chip);
return ret;
}
static int __devexit pwm_remove(struct platform_device *pdev)
{
struct vt8500_chip *chip;
chip = platform_get_drvdata(pdev);
if (chip == NULL)
return -ENODEV;
return pwmchip_remove(&chip->chip);
}
static struct platform_driver pwm_driver = {
.driver = {
.name = "vt8500-pwm",
.owner = THIS_MODULE,
},
.probe = pwm_probe,
.remove = __devexit_p(pwm_remove),
};
static int __init pwm_init(void)
{
return platform_driver_register(&pwm_driver);
}
arch_initcall(pwm_init);
static void __exit pwm_exit(void)
{
platform_driver_unregister(&pwm_driver);
}
module_exit(pwm_exit);
MODULE_LICENSE("GPL");
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