linux-stable/drivers/pwm/pwm-atmel-hlcdc.c
Uwe Kleine-König 71523d1812 pwm: Ensure pwm_apply_state() doesn't modify the state argument
It is surprising for a PWM consumer when the variable holding the
requested state is modified by pwm_apply_state(). Consider for example a
driver doing:

        #define PERIOD 5000000
        #define DUTY_LITTLE 10
        ...
        struct pwm_state state = {
                .period = PERIOD,
                .duty_cycle = DUTY_LITTLE,
                .polarity = PWM_POLARITY_NORMAL,
                .enabled = true,
        };

        pwm_apply_state(mypwm, &state);
        ...
        state.duty_cycle = PERIOD / 2;
        pwm_apply_state(mypwm, &state);

For sure the second call to pwm_apply_state() should still have
state.period = PERIOD and not something the hardware driver chose for a
reason that doesn't necessarily apply to the second call.

So declare the state argument as a pointer to a const type and adapt all
drivers' .apply callbacks.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2019-09-21 03:25:10 +02:00

317 lines
7.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2014 Free Electrons
* Copyright (C) 2014 Atmel
*
* Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/mfd/atmel-hlcdc.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#define ATMEL_HLCDC_PWMCVAL_MASK GENMASK(15, 8)
#define ATMEL_HLCDC_PWMCVAL(x) (((x) << 8) & ATMEL_HLCDC_PWMCVAL_MASK)
#define ATMEL_HLCDC_PWMPOL BIT(4)
#define ATMEL_HLCDC_PWMPS_MASK GENMASK(2, 0)
#define ATMEL_HLCDC_PWMPS_MAX 0x6
#define ATMEL_HLCDC_PWMPS(x) ((x) & ATMEL_HLCDC_PWMPS_MASK)
struct atmel_hlcdc_pwm_errata {
bool slow_clk_erratum;
bool div1_clk_erratum;
};
struct atmel_hlcdc_pwm {
struct pwm_chip chip;
struct atmel_hlcdc *hlcdc;
struct clk *cur_clk;
const struct atmel_hlcdc_pwm_errata *errata;
};
static inline struct atmel_hlcdc_pwm *to_atmel_hlcdc_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct atmel_hlcdc_pwm, chip);
}
static int atmel_hlcdc_pwm_apply(struct pwm_chip *c, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
struct atmel_hlcdc *hlcdc = chip->hlcdc;
unsigned int status;
int ret;
if (state->enabled) {
struct clk *new_clk = hlcdc->slow_clk;
u64 pwmcval = state->duty_cycle * 256;
unsigned long clk_freq;
u64 clk_period_ns;
u32 pwmcfg;
int pres;
if (!chip->errata || !chip->errata->slow_clk_erratum) {
clk_freq = clk_get_rate(new_clk);
if (!clk_freq)
return -EINVAL;
clk_period_ns = (u64)NSEC_PER_SEC * 256;
do_div(clk_period_ns, clk_freq);
}
/* Errata: cannot use slow clk on some IP revisions */
if ((chip->errata && chip->errata->slow_clk_erratum) ||
clk_period_ns > state->period) {
new_clk = hlcdc->sys_clk;
clk_freq = clk_get_rate(new_clk);
if (!clk_freq)
return -EINVAL;
clk_period_ns = (u64)NSEC_PER_SEC * 256;
do_div(clk_period_ns, clk_freq);
}
for (pres = 0; pres <= ATMEL_HLCDC_PWMPS_MAX; pres++) {
/* Errata: cannot divide by 1 on some IP revisions */
if (!pres && chip->errata &&
chip->errata->div1_clk_erratum)
continue;
if ((clk_period_ns << pres) >= state->period)
break;
}
if (pres > ATMEL_HLCDC_PWMPS_MAX)
return -EINVAL;
pwmcfg = ATMEL_HLCDC_PWMPS(pres);
if (new_clk != chip->cur_clk) {
u32 gencfg = 0;
int ret;
ret = clk_prepare_enable(new_clk);
if (ret)
return ret;
clk_disable_unprepare(chip->cur_clk);
chip->cur_clk = new_clk;
if (new_clk == hlcdc->sys_clk)
gencfg = ATMEL_HLCDC_CLKPWMSEL;
ret = regmap_update_bits(hlcdc->regmap,
ATMEL_HLCDC_CFG(0),
ATMEL_HLCDC_CLKPWMSEL,
gencfg);
if (ret)
return ret;
}
do_div(pwmcval, state->period);
/*
* The PWM duty cycle is configurable from 0/256 to 255/256 of
* the period cycle. Hence we can't set a duty cycle occupying
* the whole period cycle if we're asked to.
* Set it to 255 if pwmcval is greater than 256.
*/
if (pwmcval > 255)
pwmcval = 255;
pwmcfg |= ATMEL_HLCDC_PWMCVAL(pwmcval);
if (state->polarity == PWM_POLARITY_NORMAL)
pwmcfg |= ATMEL_HLCDC_PWMPOL;
ret = regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
ATMEL_HLCDC_PWMCVAL_MASK |
ATMEL_HLCDC_PWMPS_MASK |
ATMEL_HLCDC_PWMPOL,
pwmcfg);
if (ret)
return ret;
ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_EN,
ATMEL_HLCDC_PWM);
if (ret)
return ret;
ret = regmap_read_poll_timeout(hlcdc->regmap, ATMEL_HLCDC_SR,
status,
status & ATMEL_HLCDC_PWM,
10, 0);
if (ret)
return ret;
} else {
ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_DIS,
ATMEL_HLCDC_PWM);
if (ret)
return ret;
ret = regmap_read_poll_timeout(hlcdc->regmap, ATMEL_HLCDC_SR,
status,
!(status & ATMEL_HLCDC_PWM),
10, 0);
if (ret)
return ret;
clk_disable_unprepare(chip->cur_clk);
chip->cur_clk = NULL;
}
return 0;
}
static const struct pwm_ops atmel_hlcdc_pwm_ops = {
.apply = atmel_hlcdc_pwm_apply,
.owner = THIS_MODULE,
};
static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_at91sam9x5_errata = {
.slow_clk_erratum = true,
};
static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_sama5d3_errata = {
.div1_clk_erratum = true,
};
#ifdef CONFIG_PM_SLEEP
static int atmel_hlcdc_pwm_suspend(struct device *dev)
{
struct atmel_hlcdc_pwm *chip = dev_get_drvdata(dev);
/* Keep the periph clock enabled if the PWM is still running. */
if (pwm_is_enabled(&chip->chip.pwms[0]))
clk_disable_unprepare(chip->hlcdc->periph_clk);
return 0;
}
static int atmel_hlcdc_pwm_resume(struct device *dev)
{
struct atmel_hlcdc_pwm *chip = dev_get_drvdata(dev);
struct pwm_state state;
int ret;
pwm_get_state(&chip->chip.pwms[0], &state);
/* Re-enable the periph clock it was stopped during suspend. */
if (!state.enabled) {
ret = clk_prepare_enable(chip->hlcdc->periph_clk);
if (ret)
return ret;
}
return atmel_hlcdc_pwm_apply(&chip->chip, &chip->chip.pwms[0], &state);
}
#endif
static SIMPLE_DEV_PM_OPS(atmel_hlcdc_pwm_pm_ops,
atmel_hlcdc_pwm_suspend, atmel_hlcdc_pwm_resume);
static const struct of_device_id atmel_hlcdc_dt_ids[] = {
{
.compatible = "atmel,at91sam9n12-hlcdc",
/* 9n12 has same errata as 9x5 HLCDC PWM */
.data = &atmel_hlcdc_pwm_at91sam9x5_errata,
},
{
.compatible = "atmel,at91sam9x5-hlcdc",
.data = &atmel_hlcdc_pwm_at91sam9x5_errata,
},
{
.compatible = "atmel,sama5d2-hlcdc",
},
{
.compatible = "atmel,sama5d3-hlcdc",
.data = &atmel_hlcdc_pwm_sama5d3_errata,
},
{
.compatible = "atmel,sama5d4-hlcdc",
.data = &atmel_hlcdc_pwm_sama5d3_errata,
},
{ .compatible = "microchip,sam9x60-hlcdc", },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, atmel_hlcdc_dt_ids);
static int atmel_hlcdc_pwm_probe(struct platform_device *pdev)
{
const struct of_device_id *match;
struct device *dev = &pdev->dev;
struct atmel_hlcdc_pwm *chip;
struct atmel_hlcdc *hlcdc;
int ret;
hlcdc = dev_get_drvdata(dev->parent);
chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
ret = clk_prepare_enable(hlcdc->periph_clk);
if (ret)
return ret;
match = of_match_node(atmel_hlcdc_dt_ids, dev->parent->of_node);
if (match)
chip->errata = match->data;
chip->hlcdc = hlcdc;
chip->chip.ops = &atmel_hlcdc_pwm_ops;
chip->chip.dev = dev;
chip->chip.base = -1;
chip->chip.npwm = 1;
chip->chip.of_xlate = of_pwm_xlate_with_flags;
chip->chip.of_pwm_n_cells = 3;
ret = pwmchip_add_with_polarity(&chip->chip, PWM_POLARITY_INVERSED);
if (ret) {
clk_disable_unprepare(hlcdc->periph_clk);
return ret;
}
platform_set_drvdata(pdev, chip);
return 0;
}
static int atmel_hlcdc_pwm_remove(struct platform_device *pdev)
{
struct atmel_hlcdc_pwm *chip = platform_get_drvdata(pdev);
int ret;
ret = pwmchip_remove(&chip->chip);
if (ret)
return ret;
clk_disable_unprepare(chip->hlcdc->periph_clk);
return 0;
}
static const struct of_device_id atmel_hlcdc_pwm_dt_ids[] = {
{ .compatible = "atmel,hlcdc-pwm" },
{ /* sentinel */ },
};
static struct platform_driver atmel_hlcdc_pwm_driver = {
.driver = {
.name = "atmel-hlcdc-pwm",
.of_match_table = atmel_hlcdc_pwm_dt_ids,
.pm = &atmel_hlcdc_pwm_pm_ops,
},
.probe = atmel_hlcdc_pwm_probe,
.remove = atmel_hlcdc_pwm_remove,
};
module_platform_driver(atmel_hlcdc_pwm_driver);
MODULE_ALIAS("platform:atmel-hlcdc-pwm");
MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
MODULE_DESCRIPTION("Atmel HLCDC PWM driver");
MODULE_LICENSE("GPL v2");