linux/drivers/pwm/pwm-iqs620a.c
Uwe Kleine-König f9a8ee8c8b pwm: Always allocate PWM chip base ID dynamically
Since commit 5e5da1e9fb ("pwm: ab8500: Explicitly allocate pwm chip
base dynamically") all drivers use dynamic ID allocation explicitly. New
drivers are supposed to do the same, so remove support for driver
specified base IDs and drop all assignments in the low-level drivers.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2021-03-22 11:53:00 +01:00

259 lines
6.7 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Azoteq IQS620A PWM Generator
*
* Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
*
* Limitations:
* - The period is fixed to 1 ms and is generated continuously despite changes
* to the duty cycle or enable/disable state.
* - Changes to the duty cycle or enable/disable state take effect immediately
* and may result in a glitch during the period in which the change is made.
* - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256
* ms, the output is disabled and relies upon an external pull-down resistor
* to hold the GPIO3/LTX pin low.
*/
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/mfd/iqs62x.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#define IQS620_PWR_SETTINGS 0xd2
#define IQS620_PWR_SETTINGS_PWM_OUT BIT(7)
#define IQS620_PWM_DUTY_CYCLE 0xd8
#define IQS620_PWM_PERIOD_NS 1000000
struct iqs620_pwm_private {
struct iqs62x_core *iqs62x;
struct pwm_chip chip;
struct notifier_block notifier;
struct mutex lock;
unsigned int duty_scale;
};
static int iqs620_pwm_init(struct iqs620_pwm_private *iqs620_pwm,
unsigned int duty_scale)
{
struct iqs62x_core *iqs62x = iqs620_pwm->iqs62x;
int ret;
if (!duty_scale)
return regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
IQS620_PWR_SETTINGS_PWM_OUT, 0);
ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
duty_scale - 1);
if (ret)
return ret;
return regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
IQS620_PWR_SETTINGS_PWM_OUT, 0xff);
}
static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct iqs620_pwm_private *iqs620_pwm;
unsigned int duty_cycle;
unsigned int duty_scale;
int ret;
if (state->polarity != PWM_POLARITY_NORMAL)
return -EINVAL;
if (state->period < IQS620_PWM_PERIOD_NS)
return -EINVAL;
iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
/*
* The duty cycle generated by the device is calculated as follows:
*
* duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
*
* ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
* (inclusive). Therefore the lowest duty cycle the device can generate
* while the output is enabled is 1 / 256 ms.
*
* For lower duty cycles (e.g. 0), the PWM output is simply disabled to
* allow an external pull-down resistor to hold the GPIO3/LTX pin low.
*/
duty_cycle = min_t(u64, state->duty_cycle, IQS620_PWM_PERIOD_NS);
duty_scale = duty_cycle * 256 / IQS620_PWM_PERIOD_NS;
if (!state->enabled)
duty_scale = 0;
mutex_lock(&iqs620_pwm->lock);
ret = iqs620_pwm_init(iqs620_pwm, duty_scale);
if (!ret)
iqs620_pwm->duty_scale = duty_scale;
mutex_unlock(&iqs620_pwm->lock);
return ret;
}
static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct iqs620_pwm_private *iqs620_pwm;
iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
mutex_lock(&iqs620_pwm->lock);
/*
* Since the device cannot generate a 0% duty cycle, requests to do so
* cause subsequent calls to iqs620_pwm_get_state to report the output
* as disabled. This is not ideal, but is the best compromise based on
* the capabilities of the device.
*/
state->enabled = iqs620_pwm->duty_scale > 0;
state->duty_cycle = DIV_ROUND_UP(iqs620_pwm->duty_scale *
IQS620_PWM_PERIOD_NS, 256);
mutex_unlock(&iqs620_pwm->lock);
state->period = IQS620_PWM_PERIOD_NS;
}
static int iqs620_pwm_notifier(struct notifier_block *notifier,
unsigned long event_flags, void *context)
{
struct iqs620_pwm_private *iqs620_pwm;
int ret;
if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
return NOTIFY_DONE;
iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
notifier);
mutex_lock(&iqs620_pwm->lock);
/*
* The parent MFD driver already prints an error message in the event
* of a device reset, so nothing else is printed here unless there is
* an additional failure.
*/
ret = iqs620_pwm_init(iqs620_pwm, iqs620_pwm->duty_scale);
mutex_unlock(&iqs620_pwm->lock);
if (ret) {
dev_err(iqs620_pwm->chip.dev,
"Failed to re-initialize device: %d\n", ret);
return NOTIFY_BAD;
}
return NOTIFY_OK;
}
static const struct pwm_ops iqs620_pwm_ops = {
.apply = iqs620_pwm_apply,
.get_state = iqs620_pwm_get_state,
.owner = THIS_MODULE,
};
static void iqs620_pwm_notifier_unregister(void *context)
{
struct iqs620_pwm_private *iqs620_pwm = context;
int ret;
ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
&iqs620_pwm->notifier);
if (ret)
dev_err(iqs620_pwm->chip.dev,
"Failed to unregister notifier: %d\n", ret);
}
static int iqs620_pwm_probe(struct platform_device *pdev)
{
struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
struct iqs620_pwm_private *iqs620_pwm;
unsigned int val;
int ret;
iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
if (!iqs620_pwm)
return -ENOMEM;
platform_set_drvdata(pdev, iqs620_pwm);
iqs620_pwm->iqs62x = iqs62x;
ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
if (ret)
return ret;
if (val & IQS620_PWR_SETTINGS_PWM_OUT) {
ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
if (ret)
return ret;
iqs620_pwm->duty_scale = val + 1;
}
iqs620_pwm->chip.dev = &pdev->dev;
iqs620_pwm->chip.ops = &iqs620_pwm_ops;
iqs620_pwm->chip.npwm = 1;
mutex_init(&iqs620_pwm->lock);
iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
&iqs620_pwm->notifier);
if (ret) {
dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
return ret;
}
ret = devm_add_action_or_reset(&pdev->dev,
iqs620_pwm_notifier_unregister,
iqs620_pwm);
if (ret)
return ret;
ret = pwmchip_add(&iqs620_pwm->chip);
if (ret)
dev_err(&pdev->dev, "Failed to add device: %d\n", ret);
return ret;
}
static int iqs620_pwm_remove(struct platform_device *pdev)
{
struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev);
int ret;
ret = pwmchip_remove(&iqs620_pwm->chip);
if (ret)
dev_err(&pdev->dev, "Failed to remove device: %d\n", ret);
return ret;
}
static struct platform_driver iqs620_pwm_platform_driver = {
.driver = {
.name = "iqs620a-pwm",
},
.probe = iqs620_pwm_probe,
.remove = iqs620_pwm_remove,
};
module_platform_driver(iqs620_pwm_platform_driver);
MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:iqs620a-pwm");