/*
* Marvell Berlin PWM driver
*
* Copyright (C) 2015 Marvell Technology Group Ltd.
*
* Author: Antoine Tenart <antoine.tenart@free-electrons.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#define BERLIN_PWM_EN 0x0
#define BERLIN_PWM_ENABLE BIT(0)
#define BERLIN_PWM_CONTROL 0x4
/*
* The prescaler claims to support 8 different moduli, configured using the
* low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64,
* 256, 1024, and 4096.) However, the moduli from 4 to 1024 appear to be
* implemented by internally shifting TCNT left without adding additional
* bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff;
* for 8, 0x1fff; and so on. This means that those moduli are entirely
* useless, as we could just do the shift ourselves. The 4096 modulus is
* implemented with a real prescaler, so we do use that, but we treat it
* as a flag instead of pretending the modulus is actually configurable.
*/
#define BERLIN_PWM_PRESCALE_4096 0x7
#define BERLIN_PWM_INVERT_POLARITY BIT(3)
#define BERLIN_PWM_DUTY 0x8
#define BERLIN_PWM_TCNT 0xc
#define BERLIN_PWM_MAX_TCNT 65535
struct berlin_pwm_channel {
u32 enable;
u32 ctrl;
u32 duty;
u32 tcnt;
};
struct berlin_pwm_chip {
struct pwm_chip chip;
struct clk *clk;
void __iomem *base;
};
static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct berlin_pwm_chip, chip);
}
static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc,
unsigned int channel, unsigned long offset)
{
return readl_relaxed(bpc->base + channel * 0x10 + offset);
}
static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc,
unsigned int channel, u32 value,
unsigned long offset)
{
writel_relaxed(value, bpc->base + channel * 0x10 + offset);
}
static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct berlin_pwm_channel *channel;
channel = kzalloc(sizeof(*channel), GFP_KERNEL);
if (!channel)
return -ENOMEM;
return pwm_set_chip_data(pwm, channel);
}
static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm);
kfree(channel);
}
static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
u64 duty_ns, u64 period_ns)
{
struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
bool prescale_4096 = false;
u32 value, duty, period;
u64 cycles;
cycles = clk_get_rate(bpc->clk);
cycles *= period_ns;
do_div(cycles, NSEC_PER_SEC);
if (cycles > BERLIN_PWM_MAX_TCNT) {
prescale_4096 = true;
cycles >>= 12; // Prescaled by 4096
if (cycles > BERLIN_PWM_MAX_TCNT)
return -ERANGE;
}
period = cycles;
cycles *= duty_ns;
do_div(cycles, period_ns);
duty = cycles;
value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
if (prescale_4096)
value |= BERLIN_PWM_PRESCALE_4096;
else
value &= ~BERLIN_PWM_PRESCALE_4096;
berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY);
berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT);
return 0;
}
static int berlin_pwm_set_polarity(struct pwm_chip *chip,
struct pwm_device *pwm,
enum pwm_polarity polarity)
{
struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
u32 value;
value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
if (polarity == PWM_POLARITY_NORMAL)
value &= ~BERLIN_PWM_INVERT_POLARITY;
else
value |= BERLIN_PWM_INVERT_POLARITY;
berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
return 0;
}
static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
u32 value;
value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
value |= BERLIN_PWM_ENABLE;
berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
return 0;
}
static void berlin_pwm_disable(struct pwm_chip *chip,
struct pwm_device *pwm)
{
struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
u32 value;
value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
value &= ~BERLIN_PWM_ENABLE;
berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
}
static int berlin_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
bool enabled = pwm->state.enabled;
if (state->polarity != pwm->state.polarity) {
if (enabled) {
berlin_pwm_disable(chip, pwm);
enabled = false;
}
err = berlin_pwm_set_polarity(chip, pwm, state->polarity);
if (err)
return err;
}
if (!state->enabled) {
if (enabled)
berlin_pwm_disable(chip, pwm);
return 0;
}
err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!enabled)
return berlin_pwm_enable(chip, pwm);
return 0;
}
static const struct pwm_ops berlin_pwm_ops = {
.request = berlin_pwm_request,
.free = berlin_pwm_free,
.apply = berlin_pwm_apply,
.owner = THIS_MODULE,
};
static const struct of_device_id berlin_pwm_match[] = {
{ .compatible = "marvell,berlin-pwm" },
{ },
};
MODULE_DEVICE_TABLE(of, berlin_pwm_match);
static int berlin_pwm_probe(struct platform_device *pdev)
{
struct berlin_pwm_chip *bpc;
int ret;
bpc = devm_kzalloc(&pdev->dev, sizeof(*bpc), GFP_KERNEL);
if (!bpc)
return -ENOMEM;
bpc->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(bpc->base))
return PTR_ERR(bpc->base);
bpc->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(bpc->clk))
return PTR_ERR(bpc->clk);
ret = clk_prepare_enable(bpc->clk);
if (ret)
return ret;
bpc->chip.dev = &pdev->dev;
bpc->chip.ops = &berlin_pwm_ops;
bpc->chip.npwm = 4;
ret = pwmchip_add(&bpc->chip);
if (ret < 0) {
dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
clk_disable_unprepare(bpc->clk);
return ret;
}
platform_set_drvdata(pdev, bpc);
return 0;
}
static int berlin_pwm_remove(struct platform_device *pdev)
{
struct berlin_pwm_chip *bpc = platform_get_drvdata(pdev);
pwmchip_remove(&bpc->chip);
clk_disable_unprepare(bpc->clk);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int berlin_pwm_suspend(struct device *dev)
{
struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
unsigned int i;
for (i = 0; i < bpc->chip.npwm; i++) {
struct berlin_pwm_channel *channel;
channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
if (!channel)
continue;
channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE);
channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL);
channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY);
channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT);
}
clk_disable_unprepare(bpc->clk);
return 0;
}
static int berlin_pwm_resume(struct device *dev)
{
struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
unsigned int i;
int ret;
ret = clk_prepare_enable(bpc->clk);
if (ret)
return ret;
for (i = 0; i < bpc->chip.npwm; i++) {
struct berlin_pwm_channel *channel;
channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
if (!channel)
continue;
berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL);
berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY);
berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT);
berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE);
}
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
berlin_pwm_resume);
static struct platform_driver berlin_pwm_driver = {
.probe = berlin_pwm_probe,
.remove = berlin_pwm_remove,
.driver = {
.name = "berlin-pwm",
.of_match_table = berlin_pwm_match,
.pm = &berlin_pwm_pm_ops,
},
};
module_platform_driver(berlin_pwm_driver);
MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
MODULE_DESCRIPTION("Marvell Berlin PWM driver");
MODULE_LICENSE("GPL v2");
