linux/drivers/pwm/pwm-samsung.c
Uwe Kleine-König 1d4f9972dc pwm: samsung: Convert to platform remove callback returning void
The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2023-03-30 16:26:34 +02:00

684 lines
18 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2007 Ben Dooks
* Copyright (c) 2008 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
* Copyright (c) 2013 Tomasz Figa <tomasz.figa@gmail.com>
* Copyright (c) 2017 Samsung Electronics Co., Ltd.
*
* PWM driver for Samsung SoCs
*/
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/time.h>
/* For struct samsung_timer_variant and samsung_pwm_lock. */
#include <clocksource/samsung_pwm.h>
#define REG_TCFG0 0x00
#define REG_TCFG1 0x04
#define REG_TCON 0x08
#define REG_TCNTB(chan) (0x0c + ((chan) * 0xc))
#define REG_TCMPB(chan) (0x10 + ((chan) * 0xc))
#define TCFG0_PRESCALER_MASK 0xff
#define TCFG0_PRESCALER1_SHIFT 8
#define TCFG1_MUX_MASK 0xf
#define TCFG1_SHIFT(chan) (4 * (chan))
/*
* Each channel occupies 4 bits in TCON register, but there is a gap of 4
* bits (one channel) after channel 0, so channels have different numbering
* when accessing TCON register. See to_tcon_channel() function.
*
* In addition, the location of autoreload bit for channel 4 (TCON channel 5)
* in its set of bits is 2 as opposed to 3 for other channels.
*/
#define TCON_START(chan) BIT(4 * (chan) + 0)
#define TCON_MANUALUPDATE(chan) BIT(4 * (chan) + 1)
#define TCON_INVERT(chan) BIT(4 * (chan) + 2)
#define _TCON_AUTORELOAD(chan) BIT(4 * (chan) + 3)
#define _TCON_AUTORELOAD4(chan) BIT(4 * (chan) + 2)
#define TCON_AUTORELOAD(chan) \
((chan < 5) ? _TCON_AUTORELOAD(chan) : _TCON_AUTORELOAD4(chan))
/**
* struct samsung_pwm_channel - private data of PWM channel
* @period_ns: current period in nanoseconds programmed to the hardware
* @duty_ns: current duty time in nanoseconds programmed to the hardware
* @tin_ns: time of one timer tick in nanoseconds with current timer rate
*/
struct samsung_pwm_channel {
u32 period_ns;
u32 duty_ns;
u32 tin_ns;
};
/**
* struct samsung_pwm_chip - private data of PWM chip
* @chip: generic PWM chip
* @variant: local copy of hardware variant data
* @inverter_mask: inverter status for all channels - one bit per channel
* @disabled_mask: disabled status for all channels - one bit per channel
* @base: base address of mapped PWM registers
* @base_clk: base clock used to drive the timers
* @tclk0: external clock 0 (can be ERR_PTR if not present)
* @tclk1: external clock 1 (can be ERR_PTR if not present)
*/
struct samsung_pwm_chip {
struct pwm_chip chip;
struct samsung_pwm_variant variant;
u8 inverter_mask;
u8 disabled_mask;
void __iomem *base;
struct clk *base_clk;
struct clk *tclk0;
struct clk *tclk1;
};
#ifndef CONFIG_CLKSRC_SAMSUNG_PWM
/*
* PWM block is shared between pwm-samsung and samsung_pwm_timer drivers
* and some registers need access synchronization. If both drivers are
* compiled in, the spinlock is defined in the clocksource driver,
* otherwise following definition is used.
*
* Currently we do not need any more complex synchronization method
* because all the supported SoCs contain only one instance of the PWM
* IP. Should this change, both drivers will need to be modified to
* properly synchronize accesses to particular instances.
*/
static DEFINE_SPINLOCK(samsung_pwm_lock);
#endif
static inline
struct samsung_pwm_chip *to_samsung_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct samsung_pwm_chip, chip);
}
static inline unsigned int to_tcon_channel(unsigned int channel)
{
/* TCON register has a gap of 4 bits (1 channel) after channel 0 */
return (channel == 0) ? 0 : (channel + 1);
}
static void __pwm_samsung_manual_update(struct samsung_pwm_chip *chip,
struct pwm_device *pwm)
{
unsigned int tcon_chan = to_tcon_channel(pwm->hwpwm);
u32 tcon;
tcon = readl(chip->base + REG_TCON);
tcon |= TCON_MANUALUPDATE(tcon_chan);
writel(tcon, chip->base + REG_TCON);
tcon &= ~TCON_MANUALUPDATE(tcon_chan);
writel(tcon, chip->base + REG_TCON);
}
static void pwm_samsung_set_divisor(struct samsung_pwm_chip *pwm,
unsigned int channel, u8 divisor)
{
u8 shift = TCFG1_SHIFT(channel);
unsigned long flags;
u32 reg;
u8 bits;
bits = (fls(divisor) - 1) - pwm->variant.div_base;
spin_lock_irqsave(&samsung_pwm_lock, flags);
reg = readl(pwm->base + REG_TCFG1);
reg &= ~(TCFG1_MUX_MASK << shift);
reg |= bits << shift;
writel(reg, pwm->base + REG_TCFG1);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static int pwm_samsung_is_tdiv(struct samsung_pwm_chip *chip, unsigned int chan)
{
struct samsung_pwm_variant *variant = &chip->variant;
u32 reg;
reg = readl(chip->base + REG_TCFG1);
reg >>= TCFG1_SHIFT(chan);
reg &= TCFG1_MUX_MASK;
return (BIT(reg) & variant->tclk_mask) == 0;
}
static unsigned long pwm_samsung_get_tin_rate(struct samsung_pwm_chip *chip,
unsigned int chan)
{
unsigned long rate;
u32 reg;
rate = clk_get_rate(chip->base_clk);
reg = readl(chip->base + REG_TCFG0);
if (chan >= 2)
reg >>= TCFG0_PRESCALER1_SHIFT;
reg &= TCFG0_PRESCALER_MASK;
return rate / (reg + 1);
}
static unsigned long pwm_samsung_calc_tin(struct samsung_pwm_chip *chip,
unsigned int chan, unsigned long freq)
{
struct samsung_pwm_variant *variant = &chip->variant;
unsigned long rate;
struct clk *clk;
u8 div;
if (!pwm_samsung_is_tdiv(chip, chan)) {
clk = (chan < 2) ? chip->tclk0 : chip->tclk1;
if (!IS_ERR(clk)) {
rate = clk_get_rate(clk);
if (rate)
return rate;
}
dev_warn(chip->chip.dev,
"tclk of PWM %d is inoperational, using tdiv\n", chan);
}
rate = pwm_samsung_get_tin_rate(chip, chan);
dev_dbg(chip->chip.dev, "tin parent at %lu\n", rate);
/*
* Compare minimum PWM frequency that can be achieved with possible
* divider settings and choose the lowest divisor that can generate
* frequencies lower than requested.
*/
if (variant->bits < 32) {
/* Only for s3c24xx */
for (div = variant->div_base; div < 4; ++div)
if ((rate >> (variant->bits + div)) < freq)
break;
} else {
/*
* Other variants have enough counter bits to generate any
* requested rate, so no need to check higher divisors.
*/
div = variant->div_base;
}
pwm_samsung_set_divisor(chip, chan, BIT(div));
return rate >> div;
}
static int pwm_samsung_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
struct samsung_pwm_channel *our_chan;
if (!(our_chip->variant.output_mask & BIT(pwm->hwpwm))) {
dev_warn(chip->dev,
"tried to request PWM channel %d without output\n",
pwm->hwpwm);
return -EINVAL;
}
our_chan = kzalloc(sizeof(*our_chan), GFP_KERNEL);
if (!our_chan)
return -ENOMEM;
pwm_set_chip_data(pwm, our_chan);
return 0;
}
static void pwm_samsung_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
kfree(pwm_get_chip_data(pwm));
}
static int pwm_samsung_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
unsigned int tcon_chan = to_tcon_channel(pwm->hwpwm);
unsigned long flags;
u32 tcon;
spin_lock_irqsave(&samsung_pwm_lock, flags);
tcon = readl(our_chip->base + REG_TCON);
tcon &= ~TCON_START(tcon_chan);
tcon |= TCON_MANUALUPDATE(tcon_chan);
writel(tcon, our_chip->base + REG_TCON);
tcon &= ~TCON_MANUALUPDATE(tcon_chan);
tcon |= TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan);
writel(tcon, our_chip->base + REG_TCON);
our_chip->disabled_mask &= ~BIT(pwm->hwpwm);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
return 0;
}
static void pwm_samsung_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
unsigned int tcon_chan = to_tcon_channel(pwm->hwpwm);
unsigned long flags;
u32 tcon;
spin_lock_irqsave(&samsung_pwm_lock, flags);
tcon = readl(our_chip->base + REG_TCON);
tcon &= ~TCON_AUTORELOAD(tcon_chan);
writel(tcon, our_chip->base + REG_TCON);
/*
* In case the PWM is at 100% duty cycle, force a manual
* update to prevent the signal from staying high.
*/
if (readl(our_chip->base + REG_TCMPB(pwm->hwpwm)) == (u32)-1U)
__pwm_samsung_manual_update(our_chip, pwm);
our_chip->disabled_mask |= BIT(pwm->hwpwm);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip,
struct pwm_device *pwm)
{
unsigned long flags;
spin_lock_irqsave(&samsung_pwm_lock, flags);
__pwm_samsung_manual_update(chip, pwm);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static int __pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns, bool force_period)
{
struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
u32 tin_ns = chan->tin_ns, tcnt, tcmp, oldtcmp;
tcnt = readl(our_chip->base + REG_TCNTB(pwm->hwpwm));
oldtcmp = readl(our_chip->base + REG_TCMPB(pwm->hwpwm));
/* We need tick count for calculation, not last tick. */
++tcnt;
/* Check to see if we are changing the clock rate of the PWM. */
if (chan->period_ns != period_ns || force_period) {
unsigned long tin_rate;
u32 period;
period = NSEC_PER_SEC / period_ns;
dev_dbg(our_chip->chip.dev, "duty_ns=%d, period_ns=%d (%u)\n",
duty_ns, period_ns, period);
tin_rate = pwm_samsung_calc_tin(our_chip, pwm->hwpwm, period);
dev_dbg(our_chip->chip.dev, "tin_rate=%lu\n", tin_rate);
tin_ns = NSEC_PER_SEC / tin_rate;
tcnt = period_ns / tin_ns;
}
/* Period is too short. */
if (tcnt <= 1)
return -ERANGE;
/* Note that counters count down. */
tcmp = duty_ns / tin_ns;
/* 0% duty is not available */
if (!tcmp)
++tcmp;
tcmp = tcnt - tcmp;
/* Decrement to get tick numbers, instead of tick counts. */
--tcnt;
/* -1UL will give 100% duty. */
--tcmp;
dev_dbg(our_chip->chip.dev,
"tin_ns=%u, tcmp=%u/%u\n", tin_ns, tcmp, tcnt);
/* Update PWM registers. */
writel(tcnt, our_chip->base + REG_TCNTB(pwm->hwpwm));
writel(tcmp, our_chip->base + REG_TCMPB(pwm->hwpwm));
/*
* In case the PWM is currently at 100% duty cycle, force a manual
* update to prevent the signal staying high if the PWM is disabled
* shortly afer this update (before it autoreloaded the new values).
*/
if (oldtcmp == (u32) -1) {
dev_dbg(our_chip->chip.dev, "Forcing manual update");
pwm_samsung_manual_update(our_chip, pwm);
}
chan->period_ns = period_ns;
chan->tin_ns = tin_ns;
chan->duty_ns = duty_ns;
return 0;
}
static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
return __pwm_samsung_config(chip, pwm, duty_ns, period_ns, false);
}
static void pwm_samsung_set_invert(struct samsung_pwm_chip *chip,
unsigned int channel, bool invert)
{
unsigned int tcon_chan = to_tcon_channel(channel);
unsigned long flags;
u32 tcon;
spin_lock_irqsave(&samsung_pwm_lock, flags);
tcon = readl(chip->base + REG_TCON);
if (invert) {
chip->inverter_mask |= BIT(channel);
tcon |= TCON_INVERT(tcon_chan);
} else {
chip->inverter_mask &= ~BIT(channel);
tcon &= ~TCON_INVERT(tcon_chan);
}
writel(tcon, chip->base + REG_TCON);
spin_unlock_irqrestore(&samsung_pwm_lock, flags);
}
static int pwm_samsung_set_polarity(struct pwm_chip *chip,
struct pwm_device *pwm,
enum pwm_polarity polarity)
{
struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
bool invert = (polarity == PWM_POLARITY_NORMAL);
/* Inverted means normal in the hardware. */
pwm_samsung_set_invert(our_chip, pwm->hwpwm, invert);
return 0;
}
static int pwm_samsung_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err, enabled = pwm->state.enabled;
if (state->polarity != pwm->state.polarity) {
if (enabled) {
pwm_samsung_disable(chip, pwm);
enabled = false;
}
err = pwm_samsung_set_polarity(chip, pwm, state->polarity);
if (err)
return err;
}
if (!state->enabled) {
if (enabled)
pwm_samsung_disable(chip, pwm);
return 0;
}
/*
* We currently avoid using 64bit arithmetic by using the
* fact that anything faster than 1Hz is easily representable
* by 32bits.
*/
if (state->period > NSEC_PER_SEC)
return -ERANGE;
err = pwm_samsung_config(chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!pwm->state.enabled)
err = pwm_samsung_enable(chip, pwm);
return err;
}
static const struct pwm_ops pwm_samsung_ops = {
.request = pwm_samsung_request,
.free = pwm_samsung_free,
.apply = pwm_samsung_apply,
.owner = THIS_MODULE,
};
#ifdef CONFIG_OF
static const struct samsung_pwm_variant s3c24xx_variant = {
.bits = 16,
.div_base = 1,
.has_tint_cstat = false,
.tclk_mask = BIT(4),
};
static const struct samsung_pwm_variant s3c64xx_variant = {
.bits = 32,
.div_base = 0,
.has_tint_cstat = true,
.tclk_mask = BIT(7) | BIT(6) | BIT(5),
};
static const struct samsung_pwm_variant s5p64x0_variant = {
.bits = 32,
.div_base = 0,
.has_tint_cstat = true,
.tclk_mask = 0,
};
static const struct samsung_pwm_variant s5pc100_variant = {
.bits = 32,
.div_base = 0,
.has_tint_cstat = true,
.tclk_mask = BIT(5),
};
static const struct of_device_id samsung_pwm_matches[] = {
{ .compatible = "samsung,s3c2410-pwm", .data = &s3c24xx_variant },
{ .compatible = "samsung,s3c6400-pwm", .data = &s3c64xx_variant },
{ .compatible = "samsung,s5p6440-pwm", .data = &s5p64x0_variant },
{ .compatible = "samsung,s5pc100-pwm", .data = &s5pc100_variant },
{ .compatible = "samsung,exynos4210-pwm", .data = &s5p64x0_variant },
{},
};
MODULE_DEVICE_TABLE(of, samsung_pwm_matches);
static int pwm_samsung_parse_dt(struct samsung_pwm_chip *chip)
{
struct device_node *np = chip->chip.dev->of_node;
const struct of_device_id *match;
struct property *prop;
const __be32 *cur;
u32 val;
match = of_match_node(samsung_pwm_matches, np);
if (!match)
return -ENODEV;
memcpy(&chip->variant, match->data, sizeof(chip->variant));
of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
if (val >= SAMSUNG_PWM_NUM) {
dev_err(chip->chip.dev,
"%s: invalid channel index in samsung,pwm-outputs property\n",
__func__);
continue;
}
chip->variant.output_mask |= BIT(val);
}
return 0;
}
#else
static int pwm_samsung_parse_dt(struct samsung_pwm_chip *chip)
{
return -ENODEV;
}
#endif
static int pwm_samsung_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct samsung_pwm_chip *chip;
unsigned int chan;
int ret;
chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
if (chip == NULL)
return -ENOMEM;
chip->chip.dev = &pdev->dev;
chip->chip.ops = &pwm_samsung_ops;
chip->chip.npwm = SAMSUNG_PWM_NUM;
chip->inverter_mask = BIT(SAMSUNG_PWM_NUM) - 1;
if (IS_ENABLED(CONFIG_OF) && pdev->dev.of_node) {
ret = pwm_samsung_parse_dt(chip);
if (ret)
return ret;
} else {
if (!pdev->dev.platform_data) {
dev_err(&pdev->dev, "no platform data specified\n");
return -EINVAL;
}
memcpy(&chip->variant, pdev->dev.platform_data,
sizeof(chip->variant));
}
chip->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(chip->base))
return PTR_ERR(chip->base);
chip->base_clk = devm_clk_get(&pdev->dev, "timers");
if (IS_ERR(chip->base_clk)) {
dev_err(dev, "failed to get timer base clk\n");
return PTR_ERR(chip->base_clk);
}
ret = clk_prepare_enable(chip->base_clk);
if (ret < 0) {
dev_err(dev, "failed to enable base clock\n");
return ret;
}
for (chan = 0; chan < SAMSUNG_PWM_NUM; ++chan)
if (chip->variant.output_mask & BIT(chan))
pwm_samsung_set_invert(chip, chan, true);
/* Following clocks are optional. */
chip->tclk0 = devm_clk_get(&pdev->dev, "pwm-tclk0");
chip->tclk1 = devm_clk_get(&pdev->dev, "pwm-tclk1");
platform_set_drvdata(pdev, chip);
ret = pwmchip_add(&chip->chip);
if (ret < 0) {
dev_err(dev, "failed to register PWM chip\n");
clk_disable_unprepare(chip->base_clk);
return ret;
}
dev_dbg(dev, "base_clk at %lu, tclk0 at %lu, tclk1 at %lu\n",
clk_get_rate(chip->base_clk),
!IS_ERR(chip->tclk0) ? clk_get_rate(chip->tclk0) : 0,
!IS_ERR(chip->tclk1) ? clk_get_rate(chip->tclk1) : 0);
return 0;
}
static void pwm_samsung_remove(struct platform_device *pdev)
{
struct samsung_pwm_chip *chip = platform_get_drvdata(pdev);
pwmchip_remove(&chip->chip);
clk_disable_unprepare(chip->base_clk);
}
#ifdef CONFIG_PM_SLEEP
static int pwm_samsung_resume(struct device *dev)
{
struct samsung_pwm_chip *our_chip = dev_get_drvdata(dev);
struct pwm_chip *chip = &our_chip->chip;
unsigned int i;
for (i = 0; i < SAMSUNG_PWM_NUM; i++) {
struct pwm_device *pwm = &chip->pwms[i];
struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
if (!chan)
continue;
if (our_chip->variant.output_mask & BIT(i))
pwm_samsung_set_invert(our_chip, i,
our_chip->inverter_mask & BIT(i));
if (chan->period_ns) {
__pwm_samsung_config(chip, pwm, chan->duty_ns,
chan->period_ns, true);
/* needed to make PWM disable work on Odroid-XU3 */
pwm_samsung_manual_update(our_chip, pwm);
}
if (our_chip->disabled_mask & BIT(i))
pwm_samsung_disable(chip, pwm);
else
pwm_samsung_enable(chip, pwm);
}
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(pwm_samsung_pm_ops, NULL, pwm_samsung_resume);
static struct platform_driver pwm_samsung_driver = {
.driver = {
.name = "samsung-pwm",
.pm = &pwm_samsung_pm_ops,
.of_match_table = of_match_ptr(samsung_pwm_matches),
},
.probe = pwm_samsung_probe,
.remove_new = pwm_samsung_remove,
};
module_platform_driver(pwm_samsung_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tomasz Figa <tomasz.figa@gmail.com>");
MODULE_ALIAS("platform:samsung-pwm");