pwm-lpc32xx.c
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/*
* Copyright 2012 Alexandre Pereira da Silva <aletes.xgr@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2.
*
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
struct lpc32xx_pwm_chip {
struct pwm_chip chip;
struct clk *clk;
void __iomem *base;
};
#define PWM_ENABLE (1 << 31)
#define PWM_RELOADV(x) (((x) & 0xFF) << 8)
#define PWM_DUTY(x) ((x) & 0xFF)
#define to_lpc32xx_pwm_chip(_chip) \
container_of(_chip, struct lpc32xx_pwm_chip, chip)
static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
unsigned long long c;
int period_cycles, duty_cycles;
u32 val;
c = clk_get_rate(lpc32xx->clk) / 256;
c = c * period_ns;
do_div(c, NSEC_PER_SEC);
/* Handle high and low extremes */
if (c == 0)
c = 1;
if (c > 255)
c = 0; /* 0 set division by 256 */
period_cycles = c;
/* The duty-cycle value is as follows:
*
* DUTY-CYCLE HIGH LEVEL
* 1 99.9%
* 25 90.0%
* 128 50.0%
* 220 10.0%
* 255 0.1%
* 0 0.0%
*
* In other words, the register value is duty-cycle % 256 with
* duty-cycle in the range 1-256.
*/
c = 256 * duty_ns;
do_div(c, period_ns);
if (c > 255)
c = 255;
duty_cycles = 256 - c;
val = readl(lpc32xx->base + (pwm->hwpwm << 2));
val &= ~0xFFFF;
val |= PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles);
writel(val, lpc32xx->base + (pwm->hwpwm << 2));
return 0;
}
static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
u32 val;
int ret;
ret = clk_enable(lpc32xx->clk);
if (ret)
return ret;
val = readl(lpc32xx->base + (pwm->hwpwm << 2));
val |= PWM_ENABLE;
writel(val, lpc32xx->base + (pwm->hwpwm << 2));
return 0;
}
static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
u32 val;
val = readl(lpc32xx->base + (pwm->hwpwm << 2));
val &= ~PWM_ENABLE;
writel(val, lpc32xx->base + (pwm->hwpwm << 2));
clk_disable(lpc32xx->clk);
}
static const struct pwm_ops lpc32xx_pwm_ops = {
.config = lpc32xx_pwm_config,
.enable = lpc32xx_pwm_enable,
.disable = lpc32xx_pwm_disable,
.owner = THIS_MODULE,
};
static int lpc32xx_pwm_probe(struct platform_device *pdev)
{
struct lpc32xx_pwm_chip *lpc32xx;
struct resource *res;
int ret;
lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
if (!lpc32xx)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
lpc32xx->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(lpc32xx->base))
return PTR_ERR(lpc32xx->base);
lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(lpc32xx->clk))
return PTR_ERR(lpc32xx->clk);
lpc32xx->chip.dev = &pdev->dev;
lpc32xx->chip.ops = &lpc32xx_pwm_ops;
lpc32xx->chip.npwm = 2;
lpc32xx->chip.base = -1;
ret = pwmchip_add(&lpc32xx->chip);
if (ret < 0) {
dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, lpc32xx);
return 0;
}
static int lpc32xx_pwm_remove(struct platform_device *pdev)
{
struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
unsigned int i;
for (i = 0; i < lpc32xx->chip.npwm; i++)
pwm_disable(&lpc32xx->chip.pwms[i]);
return pwmchip_remove(&lpc32xx->chip);
}
static const struct of_device_id lpc32xx_pwm_dt_ids[] = {
{ .compatible = "nxp,lpc3220-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
static struct platform_driver lpc32xx_pwm_driver = {
.driver = {
.name = "lpc32xx-pwm",
.owner = THIS_MODULE,
.of_match_table = lpc32xx_pwm_dt_ids,
},
.probe = lpc32xx_pwm_probe,
.remove = lpc32xx_pwm_remove,
};
module_platform_driver(lpc32xx_pwm_driver);
MODULE_ALIAS("platform:lpc32xx-pwm");
MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
MODULE_DESCRIPTION("LPC32XX PWM Driver");
MODULE_LICENSE("GPL v2");