Release 4.7 drivers/pwm/pwm-bcm2835.c
/*
* Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
*
* 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/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#define PWM_CONTROL 0x000
#define PWM_CONTROL_SHIFT(x) ((x) * 8)
#define PWM_CONTROL_MASK 0xff
#define PWM_MODE 0x80
/* set timer in PWM mode */
#define PWM_ENABLE (1 << 0)
#define PWM_POLARITY (1 << 4)
#define PERIOD(x) (((x) * 0x10) + 0x10)
#define DUTY(x) (((x) * 0x10) + 0x14)
#define MIN_PERIOD 108
/* 9.2 MHz max. PWM clock */
struct bcm2835_pwm {
struct pwm_chip chip;
struct device *dev;
void __iomem *base;
struct clk *clk;
};
static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct bcm2835_pwm, chip);
}
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static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
writel(value, pc->base + PWM_CONTROL);
return 0;
}
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static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
writel(value, pc->base + PWM_CONTROL);
}
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static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
unsigned long rate = clk_get_rate(pc->clk);
unsigned long scaler;
if (!rate) {
dev_err(pc->dev, "failed to get clock rate\n");
return -EINVAL;
}
scaler = NSEC_PER_SEC / rate;
if (period_ns <= MIN_PERIOD) {
dev_err(pc->dev, "period %d not supported, minimum %d\n",
period_ns, MIN_PERIOD);
return -EINVAL;
}
writel(duty_ns / scaler, pc->base + DUTY(pwm->hwpwm));
writel(period_ns / scaler, pc->base + PERIOD(pwm->hwpwm));
return 0;
}
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static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
writel(value, pc->base + PWM_CONTROL);
return 0;
}
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static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
writel(value, pc->base + PWM_CONTROL);
}
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static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
enum pwm_polarity polarity)
{
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
u32 value;
value = readl(pc->base + PWM_CONTROL);
if (polarity == PWM_POLARITY_NORMAL)
value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
else
value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
writel(value, pc->base + PWM_CONTROL);
return 0;
}
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static const struct pwm_ops bcm2835_pwm_ops = {
.request = bcm2835_pwm_request,
.free = bcm2835_pwm_free,
.config = bcm2835_pwm_config,
.enable = bcm2835_pwm_enable,
.disable = bcm2835_pwm_disable,
.set_polarity = bcm2835_set_polarity,
.owner = THIS_MODULE,
};
static int bcm2835_pwm_probe(struct platform_device *pdev)
{
struct bcm2835_pwm *pc;
struct resource *res;
int ret;
pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
if (!pc)
return -ENOMEM;
pc->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pc->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(pc->base))
return PTR_ERR(pc->base);
pc->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pc->clk)) {
dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
return PTR_ERR(pc->clk);
}
ret = clk_prepare_enable(pc->clk);
if (ret)
return ret;
pc->chip.dev = &pdev->dev;
pc->chip.ops = &bcm2835_pwm_ops;
pc->chip.npwm = 2;
platform_set_drvdata(pdev, pc);
ret = pwmchip_add(&pc->chip);
if (ret < 0)
goto add_fail;
return 0;
add_fail:
clk_disable_unprepare(pc->clk);
return ret;
}
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static int bcm2835_pwm_remove(struct platform_device *pdev)
{
struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
clk_disable_unprepare(pc->clk);
return pwmchip_remove(&pc->chip);
}
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static const struct of_device_id bcm2835_pwm_of_match[] = {
{ .compatible = "brcm,bcm2835-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
static struct platform_driver bcm2835_pwm_driver = {
.driver = {
.name = "bcm2835-pwm",
.of_match_table = bcm2835_pwm_of_match,
},
.probe = bcm2835_pwm_probe,
.remove = bcm2835_pwm_remove,
};
module_platform_driver(bcm2835_pwm_driver);
MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
MODULE_LICENSE("GPL v2");
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