1
linux/drivers/pwm/core.c
Sean Young 7170d3beaf pwm: Make it possible to apply PWM changes in atomic context
Some PWM devices require sleeping, for example if the pwm device is
connected over I2C. However, many PWM devices could be used from atomic
context, e.g. memory mapped PWM. This is useful for, for example, the
pwm-ir-tx driver which requires precise timing. Sleeping causes havoc
with the generated IR signal.

Since not all PWM devices can support atomic context, we also add a
pwm_might_sleep() function to check if is not supported.

Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2023-12-20 16:07:06 +01:00

1132 lines
27 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic pwmlib implementation
*
* Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
* Copyright (C) 2011-2012 Avionic Design GmbH
*/
#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/of.h>
#include <linux/pwm.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <dt-bindings/pwm/pwm.h>
#define CREATE_TRACE_POINTS
#include <trace/events/pwm.h>
static DEFINE_MUTEX(pwm_lookup_lock);
static LIST_HEAD(pwm_lookup_list);
/* protects access to pwm_chips */
static DEFINE_MUTEX(pwm_lock);
static DEFINE_IDR(pwm_chips);
static struct pwm_chip *pwmchip_find_by_name(const char *name)
{
struct pwm_chip *chip;
unsigned long id, tmp;
if (!name)
return NULL;
mutex_lock(&pwm_lock);
idr_for_each_entry_ul(&pwm_chips, chip, tmp, id) {
const char *chip_name = dev_name(chip->dev);
if (chip_name && strcmp(chip_name, name) == 0) {
mutex_unlock(&pwm_lock);
return chip;
}
}
mutex_unlock(&pwm_lock);
return NULL;
}
static int pwm_device_request(struct pwm_device *pwm, const char *label)
{
int err;
if (test_bit(PWMF_REQUESTED, &pwm->flags))
return -EBUSY;
if (!try_module_get(pwm->chip->owner))
return -ENODEV;
if (pwm->chip->ops->request) {
err = pwm->chip->ops->request(pwm->chip, pwm);
if (err) {
module_put(pwm->chip->owner);
return err;
}
}
if (pwm->chip->ops->get_state) {
/*
* Zero-initialize state because most drivers are unaware of
* .usage_power. The other members of state are supposed to be
* set by lowlevel drivers. We still initialize the whole
* structure for simplicity even though this might paper over
* faulty implementations of .get_state().
*/
struct pwm_state state = { 0, };
err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
trace_pwm_get(pwm, &state, err);
if (!err)
pwm->state = state;
if (IS_ENABLED(CONFIG_PWM_DEBUG))
pwm->last = pwm->state;
}
set_bit(PWMF_REQUESTED, &pwm->flags);
pwm->label = label;
return 0;
}
struct pwm_device *
of_pwm_xlate_with_flags(struct pwm_chip *chip, const struct of_phandle_args *args)
{
struct pwm_device *pwm;
if (chip->of_pwm_n_cells < 2)
return ERR_PTR(-EINVAL);
/* flags in the third cell are optional */
if (args->args_count < 2)
return ERR_PTR(-EINVAL);
if (args->args[0] >= chip->npwm)
return ERR_PTR(-EINVAL);
pwm = pwm_request_from_chip(chip, args->args[0], NULL);
if (IS_ERR(pwm))
return pwm;
pwm->args.period = args->args[1];
pwm->args.polarity = PWM_POLARITY_NORMAL;
if (chip->of_pwm_n_cells >= 3) {
if (args->args_count > 2 && args->args[2] & PWM_POLARITY_INVERTED)
pwm->args.polarity = PWM_POLARITY_INVERSED;
}
return pwm;
}
EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);
struct pwm_device *
of_pwm_single_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
{
struct pwm_device *pwm;
if (chip->of_pwm_n_cells < 1)
return ERR_PTR(-EINVAL);
/* validate that one cell is specified, optionally with flags */
if (args->args_count != 1 && args->args_count != 2)
return ERR_PTR(-EINVAL);
pwm = pwm_request_from_chip(chip, 0, NULL);
if (IS_ERR(pwm))
return pwm;
pwm->args.period = args->args[0];
pwm->args.polarity = PWM_POLARITY_NORMAL;
if (args->args_count == 2 && args->args[2] & PWM_POLARITY_INVERTED)
pwm->args.polarity = PWM_POLARITY_INVERSED;
return pwm;
}
EXPORT_SYMBOL_GPL(of_pwm_single_xlate);
static void of_pwmchip_add(struct pwm_chip *chip)
{
if (!chip->dev || !chip->dev->of_node)
return;
if (!chip->of_xlate) {
u32 pwm_cells;
if (of_property_read_u32(chip->dev->of_node, "#pwm-cells",
&pwm_cells))
pwm_cells = 2;
chip->of_xlate = of_pwm_xlate_with_flags;
chip->of_pwm_n_cells = pwm_cells;
}
of_node_get(chip->dev->of_node);
}
static void of_pwmchip_remove(struct pwm_chip *chip)
{
if (chip->dev)
of_node_put(chip->dev->of_node);
}
static bool pwm_ops_check(const struct pwm_chip *chip)
{
const struct pwm_ops *ops = chip->ops;
if (!ops->apply)
return false;
if (IS_ENABLED(CONFIG_PWM_DEBUG) && !ops->get_state)
dev_warn(chip->dev,
"Please implement the .get_state() callback\n");
return true;
}
/**
* __pwmchip_add() - register a new PWM chip
* @chip: the PWM chip to add
* @owner: reference to the module providing the chip.
*
* Register a new PWM chip. @owner is supposed to be THIS_MODULE, use the
* pwmchip_add wrapper to do this right.
*
* Returns: 0 on success or a negative error code on failure.
*/
int __pwmchip_add(struct pwm_chip *chip, struct module *owner)
{
unsigned int i;
int ret;
if (!chip || !chip->dev || !chip->ops || !chip->npwm)
return -EINVAL;
if (!pwm_ops_check(chip))
return -EINVAL;
chip->owner = owner;
chip->pwms = kcalloc(chip->npwm, sizeof(*chip->pwms), GFP_KERNEL);
if (!chip->pwms)
return -ENOMEM;
mutex_lock(&pwm_lock);
ret = idr_alloc(&pwm_chips, chip, 0, 0, GFP_KERNEL);
if (ret < 0) {
mutex_unlock(&pwm_lock);
kfree(chip->pwms);
return ret;
}
chip->id = ret;
for (i = 0; i < chip->npwm; i++) {
struct pwm_device *pwm = &chip->pwms[i];
pwm->chip = chip;
pwm->hwpwm = i;
}
mutex_unlock(&pwm_lock);
if (IS_ENABLED(CONFIG_OF))
of_pwmchip_add(chip);
pwmchip_sysfs_export(chip);
return 0;
}
EXPORT_SYMBOL_GPL(__pwmchip_add);
/**
* pwmchip_remove() - remove a PWM chip
* @chip: the PWM chip to remove
*
* Removes a PWM chip.
*/
void pwmchip_remove(struct pwm_chip *chip)
{
pwmchip_sysfs_unexport(chip);
if (IS_ENABLED(CONFIG_OF))
of_pwmchip_remove(chip);
mutex_lock(&pwm_lock);
idr_remove(&pwm_chips, chip->id);
mutex_unlock(&pwm_lock);
kfree(chip->pwms);
}
EXPORT_SYMBOL_GPL(pwmchip_remove);
static void devm_pwmchip_remove(void *data)
{
struct pwm_chip *chip = data;
pwmchip_remove(chip);
}
int __devm_pwmchip_add(struct device *dev, struct pwm_chip *chip, struct module *owner)
{
int ret;
ret = __pwmchip_add(chip, owner);
if (ret)
return ret;
return devm_add_action_or_reset(dev, devm_pwmchip_remove, chip);
}
EXPORT_SYMBOL_GPL(__devm_pwmchip_add);
/**
* pwm_request_from_chip() - request a PWM device relative to a PWM chip
* @chip: PWM chip
* @index: per-chip index of the PWM to request
* @label: a literal description string of this PWM
*
* Returns: A pointer to the PWM device at the given index of the given PWM
* chip. A negative error code is returned if the index is not valid for the
* specified PWM chip or if the PWM device cannot be requested.
*/
struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
unsigned int index,
const char *label)
{
struct pwm_device *pwm;
int err;
if (!chip || index >= chip->npwm)
return ERR_PTR(-EINVAL);
mutex_lock(&pwm_lock);
pwm = &chip->pwms[index];
err = pwm_device_request(pwm, label);
if (err < 0)
pwm = ERR_PTR(err);
mutex_unlock(&pwm_lock);
return pwm;
}
EXPORT_SYMBOL_GPL(pwm_request_from_chip);
static void pwm_apply_debug(struct pwm_device *pwm,
const struct pwm_state *state)
{
struct pwm_state *last = &pwm->last;
struct pwm_chip *chip = pwm->chip;
struct pwm_state s1 = { 0 }, s2 = { 0 };
int err;
if (!IS_ENABLED(CONFIG_PWM_DEBUG))
return;
/* No reasonable diagnosis possible without .get_state() */
if (!chip->ops->get_state)
return;
/*
* *state was just applied. Read out the hardware state and do some
* checks.
*/
err = chip->ops->get_state(chip, pwm, &s1);
trace_pwm_get(pwm, &s1, err);
if (err)
/* If that failed there isn't much to debug */
return;
/*
* The lowlevel driver either ignored .polarity (which is a bug) or as
* best effort inverted .polarity and fixed .duty_cycle respectively.
* Undo this inversion and fixup for further tests.
*/
if (s1.enabled && s1.polarity != state->polarity) {
s2.polarity = state->polarity;
s2.duty_cycle = s1.period - s1.duty_cycle;
s2.period = s1.period;
s2.enabled = s1.enabled;
} else {
s2 = s1;
}
if (s2.polarity != state->polarity &&
state->duty_cycle < state->period)
dev_warn(chip->dev, ".apply ignored .polarity\n");
if (state->enabled &&
last->polarity == state->polarity &&
last->period > s2.period &&
last->period <= state->period)
dev_warn(chip->dev,
".apply didn't pick the best available period (requested: %llu, applied: %llu, possible: %llu)\n",
state->period, s2.period, last->period);
if (state->enabled && state->period < s2.period)
dev_warn(chip->dev,
".apply is supposed to round down period (requested: %llu, applied: %llu)\n",
state->period, s2.period);
if (state->enabled &&
last->polarity == state->polarity &&
last->period == s2.period &&
last->duty_cycle > s2.duty_cycle &&
last->duty_cycle <= state->duty_cycle)
dev_warn(chip->dev,
".apply didn't pick the best available duty cycle (requested: %llu/%llu, applied: %llu/%llu, possible: %llu/%llu)\n",
state->duty_cycle, state->period,
s2.duty_cycle, s2.period,
last->duty_cycle, last->period);
if (state->enabled && state->duty_cycle < s2.duty_cycle)
dev_warn(chip->dev,
".apply is supposed to round down duty_cycle (requested: %llu/%llu, applied: %llu/%llu)\n",
state->duty_cycle, state->period,
s2.duty_cycle, s2.period);
if (!state->enabled && s2.enabled && s2.duty_cycle > 0)
dev_warn(chip->dev,
"requested disabled, but yielded enabled with duty > 0\n");
/* reapply the state that the driver reported being configured. */
err = chip->ops->apply(chip, pwm, &s1);
trace_pwm_apply(pwm, &s1, err);
if (err) {
*last = s1;
dev_err(chip->dev, "failed to reapply current setting\n");
return;
}
*last = (struct pwm_state){ 0 };
err = chip->ops->get_state(chip, pwm, last);
trace_pwm_get(pwm, last, err);
if (err)
return;
/* reapplication of the current state should give an exact match */
if (s1.enabled != last->enabled ||
s1.polarity != last->polarity ||
(s1.enabled && s1.period != last->period) ||
(s1.enabled && s1.duty_cycle != last->duty_cycle)) {
dev_err(chip->dev,
".apply is not idempotent (ena=%d pol=%d %llu/%llu) -> (ena=%d pol=%d %llu/%llu)\n",
s1.enabled, s1.polarity, s1.duty_cycle, s1.period,
last->enabled, last->polarity, last->duty_cycle,
last->period);
}
}
/**
* __pwm_apply() - atomically apply a new state to a PWM device
* @pwm: PWM device
* @state: new state to apply
*/
static int __pwm_apply(struct pwm_device *pwm, const struct pwm_state *state)
{
struct pwm_chip *chip;
int err;
if (!pwm || !state || !state->period ||
state->duty_cycle > state->period)
return -EINVAL;
chip = pwm->chip;
if (state->period == pwm->state.period &&
state->duty_cycle == pwm->state.duty_cycle &&
state->polarity == pwm->state.polarity &&
state->enabled == pwm->state.enabled &&
state->usage_power == pwm->state.usage_power)
return 0;
err = chip->ops->apply(chip, pwm, state);
trace_pwm_apply(pwm, state, err);
if (err)
return err;
pwm->state = *state;
/*
* only do this after pwm->state was applied as some
* implementations of .get_state depend on this
*/
pwm_apply_debug(pwm, state);
return 0;
}
/**
* pwm_apply_might_sleep() - atomically apply a new state to a PWM device
* Cannot be used in atomic context.
* @pwm: PWM device
* @state: new state to apply
*/
int pwm_apply_might_sleep(struct pwm_device *pwm, const struct pwm_state *state)
{
int err;
/*
* Some lowlevel driver's implementations of .apply() make use of
* mutexes, also with some drivers only returning when the new
* configuration is active calling pwm_apply_might_sleep() from atomic context
* is a bad idea. So make it explicit that calling this function might
* sleep.
*/
might_sleep();
if (IS_ENABLED(CONFIG_PWM_DEBUG) && pwm->chip->atomic) {
/*
* Catch any drivers that have been marked as atomic but
* that will sleep anyway.
*/
non_block_start();
err = __pwm_apply(pwm, state);
non_block_end();
} else {
err = __pwm_apply(pwm, state);
}
return err;
}
EXPORT_SYMBOL_GPL(pwm_apply_might_sleep);
/**
* pwm_apply_atomic() - apply a new state to a PWM device from atomic context
* Not all PWM devices support this function, check with pwm_might_sleep().
* @pwm: PWM device
* @state: new state to apply
*/
int pwm_apply_atomic(struct pwm_device *pwm, const struct pwm_state *state)
{
WARN_ONCE(!pwm->chip->atomic,
"sleeping PWM driver used in atomic context\n");
return __pwm_apply(pwm, state);
}
EXPORT_SYMBOL_GPL(pwm_apply_atomic);
/**
* pwm_capture() - capture and report a PWM signal
* @pwm: PWM device
* @result: structure to fill with capture result
* @timeout: time to wait, in milliseconds, before giving up on capture
*
* Returns: 0 on success or a negative error code on failure.
*/
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
unsigned long timeout)
{
int err;
if (!pwm || !pwm->chip->ops)
return -EINVAL;
if (!pwm->chip->ops->capture)
return -ENOSYS;
mutex_lock(&pwm_lock);
err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout);
mutex_unlock(&pwm_lock);
return err;
}
EXPORT_SYMBOL_GPL(pwm_capture);
/**
* pwm_adjust_config() - adjust the current PWM config to the PWM arguments
* @pwm: PWM device
*
* This function will adjust the PWM config to the PWM arguments provided
* by the DT or PWM lookup table. This is particularly useful to adapt
* the bootloader config to the Linux one.
*/
int pwm_adjust_config(struct pwm_device *pwm)
{
struct pwm_state state;
struct pwm_args pargs;
pwm_get_args(pwm, &pargs);
pwm_get_state(pwm, &state);
/*
* If the current period is zero it means that either the PWM driver
* does not support initial state retrieval or the PWM has not yet
* been configured.
*
* In either case, we setup the new period and polarity, and assign a
* duty cycle of 0.
*/
if (!state.period) {
state.duty_cycle = 0;
state.period = pargs.period;
state.polarity = pargs.polarity;
return pwm_apply_might_sleep(pwm, &state);
}
/*
* Adjust the PWM duty cycle/period based on the period value provided
* in PWM args.
*/
if (pargs.period != state.period) {
u64 dutycycle = (u64)state.duty_cycle * pargs.period;
do_div(dutycycle, state.period);
state.duty_cycle = dutycycle;
state.period = pargs.period;
}
/*
* If the polarity changed, we should also change the duty cycle.
*/
if (pargs.polarity != state.polarity) {
state.polarity = pargs.polarity;
state.duty_cycle = state.period - state.duty_cycle;
}
return pwm_apply_might_sleep(pwm, &state);
}
EXPORT_SYMBOL_GPL(pwm_adjust_config);
static struct pwm_chip *fwnode_to_pwmchip(struct fwnode_handle *fwnode)
{
struct pwm_chip *chip;
unsigned long id, tmp;
mutex_lock(&pwm_lock);
idr_for_each_entry_ul(&pwm_chips, chip, tmp, id)
if (chip->dev && device_match_fwnode(chip->dev, fwnode)) {
mutex_unlock(&pwm_lock);
return chip;
}
mutex_unlock(&pwm_lock);
return ERR_PTR(-EPROBE_DEFER);
}
static struct device_link *pwm_device_link_add(struct device *dev,
struct pwm_device *pwm)
{
struct device_link *dl;
if (!dev) {
/*
* No device for the PWM consumer has been provided. It may
* impact the PM sequence ordering: the PWM supplier may get
* suspended before the consumer.
*/
dev_warn(pwm->chip->dev,
"No consumer device specified to create a link to\n");
return NULL;
}
dl = device_link_add(dev, pwm->chip->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
if (!dl) {
dev_err(dev, "failed to create device link to %s\n",
dev_name(pwm->chip->dev));
return ERR_PTR(-EINVAL);
}
return dl;
}
/**
* of_pwm_get() - request a PWM via the PWM framework
* @dev: device for PWM consumer
* @np: device node to get the PWM from
* @con_id: consumer name
*
* Returns the PWM device parsed from the phandle and index specified in the
* "pwms" property of a device tree node or a negative error-code on failure.
* Values parsed from the device tree are stored in the returned PWM device
* object.
*
* If con_id is NULL, the first PWM device listed in the "pwms" property will
* be requested. Otherwise the "pwm-names" property is used to do a reverse
* lookup of the PWM index. This also means that the "pwm-names" property
* becomes mandatory for devices that look up the PWM device via the con_id
* parameter.
*
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
* error code on failure.
*/
static struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np,
const char *con_id)
{
struct pwm_device *pwm = NULL;
struct of_phandle_args args;
struct device_link *dl;
struct pwm_chip *chip;
int index = 0;
int err;
if (con_id) {
index = of_property_match_string(np, "pwm-names", con_id);
if (index < 0)
return ERR_PTR(index);
}
err = of_parse_phandle_with_args(np, "pwms", "#pwm-cells", index,
&args);
if (err) {
pr_err("%s(): can't parse \"pwms\" property\n", __func__);
return ERR_PTR(err);
}
chip = fwnode_to_pwmchip(of_fwnode_handle(args.np));
if (IS_ERR(chip)) {
if (PTR_ERR(chip) != -EPROBE_DEFER)
pr_err("%s(): PWM chip not found\n", __func__);
pwm = ERR_CAST(chip);
goto put;
}
pwm = chip->of_xlate(chip, &args);
if (IS_ERR(pwm))
goto put;
dl = pwm_device_link_add(dev, pwm);
if (IS_ERR(dl)) {
/* of_xlate ended up calling pwm_request_from_chip() */
pwm_put(pwm);
pwm = ERR_CAST(dl);
goto put;
}
/*
* If a consumer name was not given, try to look it up from the
* "pwm-names" property if it exists. Otherwise use the name of
* the user device node.
*/
if (!con_id) {
err = of_property_read_string_index(np, "pwm-names", index,
&con_id);
if (err < 0)
con_id = np->name;
}
pwm->label = con_id;
put:
of_node_put(args.np);
return pwm;
}
/**
* acpi_pwm_get() - request a PWM via parsing "pwms" property in ACPI
* @fwnode: firmware node to get the "pwms" property from
*
* Returns the PWM device parsed from the fwnode and index specified in the
* "pwms" property or a negative error-code on failure.
* Values parsed from the device tree are stored in the returned PWM device
* object.
*
* This is analogous to of_pwm_get() except con_id is not yet supported.
* ACPI entries must look like
* Package () {"pwms", Package ()
* { <PWM device reference>, <PWM index>, <PWM period> [, <PWM flags>]}}
*
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
* error code on failure.
*/
static struct pwm_device *acpi_pwm_get(const struct fwnode_handle *fwnode)
{
struct pwm_device *pwm;
struct fwnode_reference_args args;
struct pwm_chip *chip;
int ret;
memset(&args, 0, sizeof(args));
ret = __acpi_node_get_property_reference(fwnode, "pwms", 0, 3, &args);
if (ret < 0)
return ERR_PTR(ret);
if (args.nargs < 2)
return ERR_PTR(-EPROTO);
chip = fwnode_to_pwmchip(args.fwnode);
if (IS_ERR(chip))
return ERR_CAST(chip);
pwm = pwm_request_from_chip(chip, args.args[0], NULL);
if (IS_ERR(pwm))
return pwm;
pwm->args.period = args.args[1];
pwm->args.polarity = PWM_POLARITY_NORMAL;
if (args.nargs > 2 && args.args[2] & PWM_POLARITY_INVERTED)
pwm->args.polarity = PWM_POLARITY_INVERSED;
return pwm;
}
/**
* pwm_add_table() - register PWM device consumers
* @table: array of consumers to register
* @num: number of consumers in table
*/
void pwm_add_table(struct pwm_lookup *table, size_t num)
{
mutex_lock(&pwm_lookup_lock);
while (num--) {
list_add_tail(&table->list, &pwm_lookup_list);
table++;
}
mutex_unlock(&pwm_lookup_lock);
}
/**
* pwm_remove_table() - unregister PWM device consumers
* @table: array of consumers to unregister
* @num: number of consumers in table
*/
void pwm_remove_table(struct pwm_lookup *table, size_t num)
{
mutex_lock(&pwm_lookup_lock);
while (num--) {
list_del(&table->list);
table++;
}
mutex_unlock(&pwm_lookup_lock);
}
/**
* pwm_get() - look up and request a PWM device
* @dev: device for PWM consumer
* @con_id: consumer name
*
* Lookup is first attempted using DT. If the device was not instantiated from
* a device tree, a PWM chip and a relative index is looked up via a table
* supplied by board setup code (see pwm_add_table()).
*
* Once a PWM chip has been found the specified PWM device will be requested
* and is ready to be used.
*
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
* error code on failure.
*/
struct pwm_device *pwm_get(struct device *dev, const char *con_id)
{
const struct fwnode_handle *fwnode = dev ? dev_fwnode(dev) : NULL;
const char *dev_id = dev ? dev_name(dev) : NULL;
struct pwm_device *pwm;
struct pwm_chip *chip;
struct device_link *dl;
unsigned int best = 0;
struct pwm_lookup *p, *chosen = NULL;
unsigned int match;
int err;
/* look up via DT first */
if (is_of_node(fwnode))
return of_pwm_get(dev, to_of_node(fwnode), con_id);
/* then lookup via ACPI */
if (is_acpi_node(fwnode)) {
pwm = acpi_pwm_get(fwnode);
if (!IS_ERR(pwm) || PTR_ERR(pwm) != -ENOENT)
return pwm;
}
/*
* We look up the provider in the static table typically provided by
* board setup code. We first try to lookup the consumer device by
* name. If the consumer device was passed in as NULL or if no match
* was found, we try to find the consumer by directly looking it up
* by name.
*
* If a match is found, the provider PWM chip is looked up by name
* and a PWM device is requested using the PWM device per-chip index.
*
* The lookup algorithm was shamelessly taken from the clock
* framework:
*
* We do slightly fuzzy matching here:
* An entry with a NULL ID is assumed to be a wildcard.
* If an entry has a device ID, it must match
* If an entry has a connection ID, it must match
* Then we take the most specific entry - with the following order
* of precedence: dev+con > dev only > con only.
*/
mutex_lock(&pwm_lookup_lock);
list_for_each_entry(p, &pwm_lookup_list, list) {
match = 0;
if (p->dev_id) {
if (!dev_id || strcmp(p->dev_id, dev_id))
continue;
match += 2;
}
if (p->con_id) {
if (!con_id || strcmp(p->con_id, con_id))
continue;
match += 1;
}
if (match > best) {
chosen = p;
if (match != 3)
best = match;
else
break;
}
}
mutex_unlock(&pwm_lookup_lock);
if (!chosen)
return ERR_PTR(-ENODEV);
chip = pwmchip_find_by_name(chosen->provider);
/*
* If the lookup entry specifies a module, load the module and retry
* the PWM chip lookup. This can be used to work around driver load
* ordering issues if driver's can't be made to properly support the
* deferred probe mechanism.
*/
if (!chip && chosen->module) {
err = request_module(chosen->module);
if (err == 0)
chip = pwmchip_find_by_name(chosen->provider);
}
if (!chip)
return ERR_PTR(-EPROBE_DEFER);
pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
if (IS_ERR(pwm))
return pwm;
dl = pwm_device_link_add(dev, pwm);
if (IS_ERR(dl)) {
pwm_put(pwm);
return ERR_CAST(dl);
}
pwm->args.period = chosen->period;
pwm->args.polarity = chosen->polarity;
return pwm;
}
EXPORT_SYMBOL_GPL(pwm_get);
/**
* pwm_put() - release a PWM device
* @pwm: PWM device
*/
void pwm_put(struct pwm_device *pwm)
{
if (!pwm)
return;
mutex_lock(&pwm_lock);
if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
pr_warn("PWM device already freed\n");
goto out;
}
if (pwm->chip->ops->free)
pwm->chip->ops->free(pwm->chip, pwm);
pwm->label = NULL;
module_put(pwm->chip->owner);
out:
mutex_unlock(&pwm_lock);
}
EXPORT_SYMBOL_GPL(pwm_put);
static void devm_pwm_release(void *pwm)
{
pwm_put(pwm);
}
/**
* devm_pwm_get() - resource managed pwm_get()
* @dev: device for PWM consumer
* @con_id: consumer name
*
* This function performs like pwm_get() but the acquired PWM device will
* automatically be released on driver detach.
*
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
* error code on failure.
*/
struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id)
{
struct pwm_device *pwm;
int ret;
pwm = pwm_get(dev, con_id);
if (IS_ERR(pwm))
return pwm;
ret = devm_add_action_or_reset(dev, devm_pwm_release, pwm);
if (ret)
return ERR_PTR(ret);
return pwm;
}
EXPORT_SYMBOL_GPL(devm_pwm_get);
/**
* devm_fwnode_pwm_get() - request a resource managed PWM from firmware node
* @dev: device for PWM consumer
* @fwnode: firmware node to get the PWM from
* @con_id: consumer name
*
* Returns the PWM device parsed from the firmware node. See of_pwm_get() and
* acpi_pwm_get() for a detailed description.
*
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
* error code on failure.
*/
struct pwm_device *devm_fwnode_pwm_get(struct device *dev,
struct fwnode_handle *fwnode,
const char *con_id)
{
struct pwm_device *pwm = ERR_PTR(-ENODEV);
int ret;
if (is_of_node(fwnode))
pwm = of_pwm_get(dev, to_of_node(fwnode), con_id);
else if (is_acpi_node(fwnode))
pwm = acpi_pwm_get(fwnode);
if (IS_ERR(pwm))
return pwm;
ret = devm_add_action_or_reset(dev, devm_pwm_release, pwm);
if (ret)
return ERR_PTR(ret);
return pwm;
}
EXPORT_SYMBOL_GPL(devm_fwnode_pwm_get);
#ifdef CONFIG_DEBUG_FS
static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
{
unsigned int i;
for (i = 0; i < chip->npwm; i++) {
struct pwm_device *pwm = &chip->pwms[i];
struct pwm_state state;
pwm_get_state(pwm, &state);
seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
if (test_bit(PWMF_REQUESTED, &pwm->flags))
seq_puts(s, " requested");
if (state.enabled)
seq_puts(s, " enabled");
seq_printf(s, " period: %llu ns", state.period);
seq_printf(s, " duty: %llu ns", state.duty_cycle);
seq_printf(s, " polarity: %s",
state.polarity ? "inverse" : "normal");
if (state.usage_power)
seq_puts(s, " usage_power");
seq_puts(s, "\n");
}
}
static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
{
unsigned long id = *pos;
void *ret;
mutex_lock(&pwm_lock);
s->private = "";
ret = idr_get_next_ul(&pwm_chips, &id);
*pos = id;
return ret;
}
static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
unsigned long id = *pos + 1;
void *ret;
s->private = "\n";
ret = idr_get_next_ul(&pwm_chips, &id);
*pos = id;
return ret;
}
static void pwm_seq_stop(struct seq_file *s, void *v)
{
mutex_unlock(&pwm_lock);
}
static int pwm_seq_show(struct seq_file *s, void *v)
{
struct pwm_chip *chip = v;
seq_printf(s, "%s%d: %s/%s, %d PWM device%s\n",
(char *)s->private, chip->id,
chip->dev->bus ? chip->dev->bus->name : "no-bus",
dev_name(chip->dev), chip->npwm,
(chip->npwm != 1) ? "s" : "");
pwm_dbg_show(chip, s);
return 0;
}
static const struct seq_operations pwm_debugfs_sops = {
.start = pwm_seq_start,
.next = pwm_seq_next,
.stop = pwm_seq_stop,
.show = pwm_seq_show,
};
DEFINE_SEQ_ATTRIBUTE(pwm_debugfs);
static int __init pwm_debugfs_init(void)
{
debugfs_create_file("pwm", 0444, NULL, NULL, &pwm_debugfs_fops);
return 0;
}
subsys_initcall(pwm_debugfs_init);
#endif /* CONFIG_DEBUG_FS */