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linux-next/drivers/pwm/pwm-pca9685.c
Sven Van Asbroeck 9cc5f232a4 pwm: pca9685: Fix PWM/GPIO inter-operation
This driver allows pwms to be requested as gpios via gpiolib. Obviously,
it should not be allowed to request a GPIO when its corresponding PWM is
already requested (and vice versa). So it requires some exclusion code.

Given that the PWMm and GPIO cores are not synchronized with respect to
each other, this exclusion code will also require proper
synchronization.

Such a mechanism was in place, but was inadvertently removed by Uwe's
clean-up in commit e926b12c61 ("pwm: Clear chip_data in pwm_put()").

Upon revisiting the synchronization mechanism, we found that
theoretically, it could allow two threads to successfully request
conflicting PWMs/GPIOs.

Replace with a bitmap which tracks PWMs in-use, plus a mutex. As long as
PWM and GPIO's respective request/free functions modify the in-use
bitmap while holding the mutex, proper synchronization will be
guaranteed.

Reported-by: YueHaibing <yuehaibing@huawei.com>
Fixes: e926b12c61 ("pwm: Clear chip_data in pwm_put()")
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: YueHaibing <yuehaibing@huawei.com>
Link: https://lkml.org/lkml/2019/5/31/963
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[cg: Tested on an i.MX6Q board with two NXP PCA9685 chips]
Tested-by: Clemens Gruber <clemens.gruber@pqgruber.com>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com> # cg's rebase
Link: https://lore.kernel.org/lkml/20200330160238.GD2817345@ulmo/
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2020-04-03 21:41:42 +02:00

584 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for PCA9685 16-channel 12-bit PWM LED controller
*
* Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
* Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
*
* based on the pwm-twl-led.c driver
*/
#include <linux/acpi.h>
#include <linux/gpio/driver.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/pm_runtime.h>
#include <linux/bitmap.h>
/*
* Because the PCA9685 has only one prescaler per chip, changing the period of
* one channel affects the period of all 16 PWM outputs!
* However, the ratio between each configured duty cycle and the chip-wide
* period remains constant, because the OFF time is set in proportion to the
* counter range.
*/
#define PCA9685_MODE1 0x00
#define PCA9685_MODE2 0x01
#define PCA9685_SUBADDR1 0x02
#define PCA9685_SUBADDR2 0x03
#define PCA9685_SUBADDR3 0x04
#define PCA9685_ALLCALLADDR 0x05
#define PCA9685_LEDX_ON_L 0x06
#define PCA9685_LEDX_ON_H 0x07
#define PCA9685_LEDX_OFF_L 0x08
#define PCA9685_LEDX_OFF_H 0x09
#define PCA9685_ALL_LED_ON_L 0xFA
#define PCA9685_ALL_LED_ON_H 0xFB
#define PCA9685_ALL_LED_OFF_L 0xFC
#define PCA9685_ALL_LED_OFF_H 0xFD
#define PCA9685_PRESCALE 0xFE
#define PCA9685_PRESCALE_MIN 0x03 /* => max. frequency of 1526 Hz */
#define PCA9685_PRESCALE_MAX 0xFF /* => min. frequency of 24 Hz */
#define PCA9685_COUNTER_RANGE 4096
#define PCA9685_DEFAULT_PERIOD 5000000 /* Default period_ns = 1/200 Hz */
#define PCA9685_OSC_CLOCK_MHZ 25 /* Internal oscillator with 25 MHz */
#define PCA9685_NUMREGS 0xFF
#define PCA9685_MAXCHAN 0x10
#define LED_FULL (1 << 4)
#define MODE1_SLEEP (1 << 4)
#define MODE2_INVRT (1 << 4)
#define MODE2_OUTDRV (1 << 2)
#define LED_N_ON_H(N) (PCA9685_LEDX_ON_H + (4 * (N)))
#define LED_N_ON_L(N) (PCA9685_LEDX_ON_L + (4 * (N)))
#define LED_N_OFF_H(N) (PCA9685_LEDX_OFF_H + (4 * (N)))
#define LED_N_OFF_L(N) (PCA9685_LEDX_OFF_L + (4 * (N)))
struct pca9685 {
struct pwm_chip chip;
struct regmap *regmap;
int period_ns;
#if IS_ENABLED(CONFIG_GPIOLIB)
struct mutex lock;
struct gpio_chip gpio;
DECLARE_BITMAP(pwms_inuse, PCA9685_MAXCHAN + 1);
#endif
};
static inline struct pca9685 *to_pca(struct pwm_chip *chip)
{
return container_of(chip, struct pca9685, chip);
}
#if IS_ENABLED(CONFIG_GPIOLIB)
static bool pca9685_pwm_test_and_set_inuse(struct pca9685 *pca, int pwm_idx)
{
bool is_inuse;
mutex_lock(&pca->lock);
if (pwm_idx >= PCA9685_MAXCHAN) {
/*
* "all LEDs" channel:
* pretend already in use if any of the PWMs are requested
*/
if (!bitmap_empty(pca->pwms_inuse, PCA9685_MAXCHAN)) {
is_inuse = true;
goto out;
}
} else {
/*
* regular channel:
* pretend already in use if the "all LEDs" channel is requested
*/
if (test_bit(PCA9685_MAXCHAN, pca->pwms_inuse)) {
is_inuse = true;
goto out;
}
}
is_inuse = test_and_set_bit(pwm_idx, pca->pwms_inuse);
out:
mutex_unlock(&pca->lock);
return is_inuse;
}
static void pca9685_pwm_clear_inuse(struct pca9685 *pca, int pwm_idx)
{
mutex_lock(&pca->lock);
clear_bit(pwm_idx, pca->pwms_inuse);
mutex_unlock(&pca->lock);
}
static int pca9685_pwm_gpio_request(struct gpio_chip *gpio, unsigned int offset)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
if (pca9685_pwm_test_and_set_inuse(pca, offset))
return -EBUSY;
pm_runtime_get_sync(pca->chip.dev);
return 0;
}
static int pca9685_pwm_gpio_get(struct gpio_chip *gpio, unsigned int offset)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
struct pwm_device *pwm = &pca->chip.pwms[offset];
unsigned int value;
regmap_read(pca->regmap, LED_N_ON_H(pwm->hwpwm), &value);
return value & LED_FULL;
}
static void pca9685_pwm_gpio_set(struct gpio_chip *gpio, unsigned int offset,
int value)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
struct pwm_device *pwm = &pca->chip.pwms[offset];
unsigned int on = value ? LED_FULL : 0;
/* Clear both OFF registers */
regmap_write(pca->regmap, LED_N_OFF_L(pwm->hwpwm), 0);
regmap_write(pca->regmap, LED_N_OFF_H(pwm->hwpwm), 0);
/* Set the full ON bit */
regmap_write(pca->regmap, LED_N_ON_H(pwm->hwpwm), on);
}
static void pca9685_pwm_gpio_free(struct gpio_chip *gpio, unsigned int offset)
{
struct pca9685 *pca = gpiochip_get_data(gpio);
pca9685_pwm_gpio_set(gpio, offset, 0);
pm_runtime_put(pca->chip.dev);
pca9685_pwm_clear_inuse(pca, offset);
}
static int pca9685_pwm_gpio_get_direction(struct gpio_chip *chip,
unsigned int offset)
{
/* Always out */
return GPIO_LINE_DIRECTION_OUT;
}
static int pca9685_pwm_gpio_direction_input(struct gpio_chip *gpio,
unsigned int offset)
{
return -EINVAL;
}
static int pca9685_pwm_gpio_direction_output(struct gpio_chip *gpio,
unsigned int offset, int value)
{
pca9685_pwm_gpio_set(gpio, offset, value);
return 0;
}
/*
* The PCA9685 has a bit for turning the PWM output full off or on. Some
* boards like Intel Galileo actually uses these as normal GPIOs so we
* expose a GPIO chip here which can exclusively take over the underlying
* PWM channel.
*/
static int pca9685_pwm_gpio_probe(struct pca9685 *pca)
{
struct device *dev = pca->chip.dev;
mutex_init(&pca->lock);
pca->gpio.label = dev_name(dev);
pca->gpio.parent = dev;
pca->gpio.request = pca9685_pwm_gpio_request;
pca->gpio.free = pca9685_pwm_gpio_free;
pca->gpio.get_direction = pca9685_pwm_gpio_get_direction;
pca->gpio.direction_input = pca9685_pwm_gpio_direction_input;
pca->gpio.direction_output = pca9685_pwm_gpio_direction_output;
pca->gpio.get = pca9685_pwm_gpio_get;
pca->gpio.set = pca9685_pwm_gpio_set;
pca->gpio.base = -1;
pca->gpio.ngpio = PCA9685_MAXCHAN;
pca->gpio.can_sleep = true;
return devm_gpiochip_add_data(dev, &pca->gpio, pca);
}
#else
static inline bool pca9685_pwm_test_and_set_inuse(struct pca9685 *pca,
int pwm_idx)
{
return false;
}
static inline void
pca9685_pwm_clear_inuse(struct pca9685 *pca, int pwm_idx)
{
}
static inline int pca9685_pwm_gpio_probe(struct pca9685 *pca)
{
return 0;
}
#endif
static void pca9685_set_sleep_mode(struct pca9685 *pca, bool enable)
{
regmap_update_bits(pca->regmap, PCA9685_MODE1,
MODE1_SLEEP, enable ? MODE1_SLEEP : 0);
if (!enable) {
/* Wait 500us for the oscillator to be back up */
udelay(500);
}
}
static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct pca9685 *pca = to_pca(chip);
unsigned long long duty;
unsigned int reg;
int prescale;
if (period_ns != pca->period_ns) {
prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
PCA9685_COUNTER_RANGE * 1000) - 1;
if (prescale >= PCA9685_PRESCALE_MIN &&
prescale <= PCA9685_PRESCALE_MAX) {
/*
* putting the chip briefly into SLEEP mode
* at this point won't interfere with the
* pm_runtime framework, because the pm_runtime
* state is guaranteed active here.
*/
/* Put chip into sleep mode */
pca9685_set_sleep_mode(pca, true);
/* Change the chip-wide output frequency */
regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);
/* Wake the chip up */
pca9685_set_sleep_mode(pca, false);
pca->period_ns = period_ns;
} else {
dev_err(chip->dev,
"prescaler not set: period out of bounds!\n");
return -EINVAL;
}
}
if (duty_ns < 1) {
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_H;
else
reg = LED_N_OFF_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, LED_FULL);
return 0;
}
if (duty_ns == period_ns) {
/* Clear both OFF registers */
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_L;
else
reg = LED_N_OFF_L(pwm->hwpwm);
regmap_write(pca->regmap, reg, 0x0);
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_H;
else
reg = LED_N_OFF_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, 0x0);
/* Set the full ON bit */
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_ON_H;
else
reg = LED_N_ON_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, LED_FULL);
return 0;
}
duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
duty = DIV_ROUND_UP_ULL(duty, period_ns);
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_L;
else
reg = LED_N_OFF_L(pwm->hwpwm);
regmap_write(pca->regmap, reg, (int)duty & 0xff);
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_H;
else
reg = LED_N_OFF_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);
/* Clear the full ON bit, otherwise the set OFF time has no effect */
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_ON_H;
else
reg = LED_N_ON_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, 0);
return 0;
}
static int pca9685_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
unsigned int reg;
/*
* The PWM subsystem does not support a pre-delay.
* So, set the ON-timeout to 0
*/
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_ON_L;
else
reg = LED_N_ON_L(pwm->hwpwm);
regmap_write(pca->regmap, reg, 0);
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_ON_H;
else
reg = LED_N_ON_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, 0);
/*
* Clear the full-off bit.
* It has precedence over the others and must be off.
*/
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_H;
else
reg = LED_N_OFF_H(pwm->hwpwm);
regmap_update_bits(pca->regmap, reg, LED_FULL, 0x0);
return 0;
}
static void pca9685_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
unsigned int reg;
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_H;
else
reg = LED_N_OFF_H(pwm->hwpwm);
regmap_write(pca->regmap, reg, LED_FULL);
/* Clear the LED_OFF counter. */
if (pwm->hwpwm >= PCA9685_MAXCHAN)
reg = PCA9685_ALL_LED_OFF_L;
else
reg = LED_N_OFF_L(pwm->hwpwm);
regmap_write(pca->regmap, reg, 0x0);
}
static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
if (pca9685_pwm_test_and_set_inuse(pca, pwm->hwpwm))
return -EBUSY;
pm_runtime_get_sync(chip->dev);
return 0;
}
static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pca9685 *pca = to_pca(chip);
pca9685_pwm_disable(chip, pwm);
pm_runtime_put(chip->dev);
pca9685_pwm_clear_inuse(pca, pwm->hwpwm);
}
static const struct pwm_ops pca9685_pwm_ops = {
.enable = pca9685_pwm_enable,
.disable = pca9685_pwm_disable,
.config = pca9685_pwm_config,
.request = pca9685_pwm_request,
.free = pca9685_pwm_free,
.owner = THIS_MODULE,
};
static const struct regmap_config pca9685_regmap_i2c_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = PCA9685_NUMREGS,
.cache_type = REGCACHE_NONE,
};
static int pca9685_pwm_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct pca9685 *pca;
int ret;
int mode2;
pca = devm_kzalloc(&client->dev, sizeof(*pca), GFP_KERNEL);
if (!pca)
return -ENOMEM;
pca->regmap = devm_regmap_init_i2c(client, &pca9685_regmap_i2c_config);
if (IS_ERR(pca->regmap)) {
ret = PTR_ERR(pca->regmap);
dev_err(&client->dev, "Failed to initialize register map: %d\n",
ret);
return ret;
}
pca->period_ns = PCA9685_DEFAULT_PERIOD;
i2c_set_clientdata(client, pca);
regmap_read(pca->regmap, PCA9685_MODE2, &mode2);
if (device_property_read_bool(&client->dev, "invert"))
mode2 |= MODE2_INVRT;
else
mode2 &= ~MODE2_INVRT;
if (device_property_read_bool(&client->dev, "open-drain"))
mode2 &= ~MODE2_OUTDRV;
else
mode2 |= MODE2_OUTDRV;
regmap_write(pca->regmap, PCA9685_MODE2, mode2);
/* clear all "full off" bits */
regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);
pca->chip.ops = &pca9685_pwm_ops;
/* add an extra channel for ALL_LED */
pca->chip.npwm = PCA9685_MAXCHAN + 1;
pca->chip.dev = &client->dev;
pca->chip.base = -1;
ret = pwmchip_add(&pca->chip);
if (ret < 0)
return ret;
ret = pca9685_pwm_gpio_probe(pca);
if (ret < 0) {
pwmchip_remove(&pca->chip);
return ret;
}
/* the chip comes out of power-up in the active state */
pm_runtime_set_active(&client->dev);
/*
* enable will put the chip into suspend, which is what we
* want as all outputs are disabled at this point
*/
pm_runtime_enable(&client->dev);
return 0;
}
static int pca9685_pwm_remove(struct i2c_client *client)
{
struct pca9685 *pca = i2c_get_clientdata(client);
int ret;
ret = pwmchip_remove(&pca->chip);
if (ret)
return ret;
pm_runtime_disable(&client->dev);
return 0;
}
static int __maybe_unused pca9685_pwm_runtime_suspend(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct pca9685 *pca = i2c_get_clientdata(client);
pca9685_set_sleep_mode(pca, true);
return 0;
}
static int __maybe_unused pca9685_pwm_runtime_resume(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct pca9685 *pca = i2c_get_clientdata(client);
pca9685_set_sleep_mode(pca, false);
return 0;
}
static const struct i2c_device_id pca9685_id[] = {
{ "pca9685", 0 },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(i2c, pca9685_id);
#ifdef CONFIG_ACPI
static const struct acpi_device_id pca9685_acpi_ids[] = {
{ "INT3492", 0 },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(acpi, pca9685_acpi_ids);
#endif
#ifdef CONFIG_OF
static const struct of_device_id pca9685_dt_ids[] = {
{ .compatible = "nxp,pca9685-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
#endif
static const struct dev_pm_ops pca9685_pwm_pm = {
SET_RUNTIME_PM_OPS(pca9685_pwm_runtime_suspend,
pca9685_pwm_runtime_resume, NULL)
};
static struct i2c_driver pca9685_i2c_driver = {
.driver = {
.name = "pca9685-pwm",
.acpi_match_table = ACPI_PTR(pca9685_acpi_ids),
.of_match_table = of_match_ptr(pca9685_dt_ids),
.pm = &pca9685_pwm_pm,
},
.probe = pca9685_pwm_probe,
.remove = pca9685_pwm_remove,
.id_table = pca9685_id,
};
module_i2c_driver(pca9685_i2c_driver);
MODULE_AUTHOR("Steffen Trumtrar <s.trumtrar@pengutronix.de>");
MODULE_DESCRIPTION("PWM driver for PCA9685");
MODULE_LICENSE("GPL");