pwm-puv3.c
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/*
* linux/arch/unicore32/kernel/pwm.c
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
* Copyright (C) 2001-2010 Guan Xuetao
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <asm/div64.h>
#include <mach/hardware.h>
struct puv3_pwm_chip {
struct pwm_chip chip;
void __iomem *base;
struct clk *clk;
};
static inline struct puv3_pwm_chip *to_puv3(struct pwm_chip *chip)
{
return container_of(chip, struct puv3_pwm_chip, chip);
}
/*
* period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
*/
static int puv3_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
unsigned long period_cycles, prescale, pv, dc;
struct puv3_pwm_chip *puv3 = to_puv3(chip);
unsigned long long c;
c = clk_get_rate(puv3->clk);
c = c * period_ns;
do_div(c, 1000000000);
period_cycles = c;
if (period_cycles < 1)
period_cycles = 1;
prescale = (period_cycles - 1) / 1024;
pv = period_cycles / (prescale + 1) - 1;
if (prescale > 63)
return -EINVAL;
if (duty_ns == period_ns)
dc = OST_PWMDCCR_FDCYCLE;
else
dc = (pv + 1) * duty_ns / period_ns;
/*
* NOTE: the clock to PWM has to be enabled first
* before writing to the registers
*/
clk_prepare_enable(puv3->clk);
writel(prescale, puv3->base + OST_PWM_PWCR);
writel(pv - dc, puv3->base + OST_PWM_DCCR);
writel(pv, puv3->base + OST_PWM_PCR);
clk_disable_unprepare(puv3->clk);
return 0;
}
static int puv3_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct puv3_pwm_chip *puv3 = to_puv3(chip);
return clk_prepare_enable(puv3->clk);
}
static void puv3_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct puv3_pwm_chip *puv3 = to_puv3(chip);
clk_disable_unprepare(puv3->clk);
}
static const struct pwm_ops puv3_pwm_ops = {
.config = puv3_pwm_config,
.enable = puv3_pwm_enable,
.disable = puv3_pwm_disable,
.owner = THIS_MODULE,
};
static int pwm_probe(struct platform_device *pdev)
{
struct puv3_pwm_chip *puv3;
struct resource *r;
int ret;
puv3 = devm_kzalloc(&pdev->dev, sizeof(*puv3), GFP_KERNEL);
if (puv3 == NULL) {
dev_err(&pdev->dev, "failed to allocate memory\n");
return -ENOMEM;
}
puv3->clk = devm_clk_get(&pdev->dev, "OST_CLK");
if (IS_ERR(puv3->clk))
return PTR_ERR(puv3->clk);
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
puv3->base = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(puv3->base))
return PTR_ERR(puv3->base);
puv3->chip.dev = &pdev->dev;
puv3->chip.ops = &puv3_pwm_ops;
puv3->chip.base = -1;
puv3->chip.npwm = 1;
ret = pwmchip_add(&puv3->chip);
if (ret < 0) {
dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, puv3);
return 0;
}
static int pwm_remove(struct platform_device *pdev)
{
struct puv3_pwm_chip *puv3 = platform_get_drvdata(pdev);
return pwmchip_remove(&puv3->chip);
}
static struct platform_driver puv3_pwm_driver = {
.driver = {
.name = "PKUnity-v3-PWM",
.owner = THIS_MODULE,
},
.probe = pwm_probe,
.remove = pwm_remove,
};
module_platform_driver(puv3_pwm_driver);
MODULE_LICENSE("GPL v2");