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core.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic pwmlib implementation
*
* Copyright (C) 2011 Sascha Hauer <[email protected]>
* Copyright (C) 2011-2012 Avionic Design GmbH
*/
#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/radix-tree.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>
#define MAX_PWMS 1024
static DEFINE_MUTEX(pwm_lookup_lock);
static LIST_HEAD(pwm_lookup_list);
static DEFINE_MUTEX(pwm_lock);
static LIST_HEAD(pwm_chips);
static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
static RADIX_TREE(pwm_tree, GFP_KERNEL);
static struct pwm_device *pwm_to_device(unsigned int pwm)
{
return radix_tree_lookup(&pwm_tree, pwm);
}
static int alloc_pwms(unsigned int count)
{
unsigned int start;
start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, 0,
count, 0);
if (start + count > MAX_PWMS)
return -ENOSPC;
return start;
}
static void free_pwms(struct pwm_chip *chip)
{
unsigned int i;
for (i = 0; i < chip->npwm; i++) {
struct pwm_device *pwm = &chip->pwms[i];
radix_tree_delete(&pwm_tree, pwm->pwm);
}
bitmap_clear(allocated_pwms, chip->base, chip->npwm);
kfree(chip->pwms);
chip->pwms = NULL;
}
static struct pwm_chip *pwmchip_find_by_name(const char *name)
{
struct pwm_chip *chip;
if (!name)
return NULL;
mutex_lock(&pwm_lock);
list_for_each_entry(chip, &pwm_chips, list) {
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->ops->owner))
return -ENODEV;
if (pwm->chip->ops->request) {
err = pwm->chip->ops->request(pwm->chip, pwm);
if (err) {
module_put(pwm->chip->ops->owner);
return err;
}
}
if (pwm->chip->ops->get_state) {
pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
trace_pwm_get(pwm, &pwm->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 *pc, const struct of_phandle_args *args)
{
struct pwm_device *pwm;
if (pc->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] >= pc->npwm)
return ERR_PTR(-EINVAL);
pwm = pwm_request_from_chip(pc, args->args[0], NULL);
if (IS_ERR(pwm))
return pwm;
pwm->args.period = args->args[1];
pwm->args.polarity = PWM_POLARITY_NORMAL;
if (pc->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 *pc, const struct of_phandle_args *args)
{
struct pwm_device *pwm;
if (pc->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(pc, 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);
}
/**
* pwm_set_chip_data() - set private chip data for a PWM
* @pwm: PWM device
* @data: pointer to chip-specific data
*
* Returns: 0 on success or a negative error code on failure.
*/
int pwm_set_chip_data(struct pwm_device *pwm, void *data)
{
if (!pwm)
return -EINVAL;
pwm->chip_data = data;
return 0;
}
EXPORT_SYMBOL_GPL(pwm_set_chip_data);
/**
* pwm_get_chip_data() - get private chip data for a PWM
* @pwm: PWM device
*
* Returns: A pointer to the chip-private data for the PWM device.
*/
void *pwm_get_chip_data(struct pwm_device *pwm)
{
return pwm ? pwm->chip_data : NULL;
}
EXPORT_SYMBOL_GPL(pwm_get_chip_data);
static bool pwm_ops_check(const struct pwm_chip *chip)
{
const struct pwm_ops *ops = chip->ops;
/* driver supports legacy, non-atomic operation */
if (ops->config && ops->enable && ops->disable) {
if (IS_ENABLED(CONFIG_PWM_DEBUG))
dev_warn(chip->dev,
"Driver needs updating to atomic API\n");
return true;
}
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
*
* Register a new PWM chip.
*
* Returns: 0 on success or a negative error code on failure.
*/
int pwmchip_add(struct pwm_chip *chip)
{
struct pwm_device *pwm;
unsigned int i;
int ret;
if (!chip || !chip->dev || !chip->ops || !chip->npwm)
return -EINVAL;
if (!pwm_ops_check(chip))
return -EINVAL;
mutex_lock(&pwm_lock);
ret = alloc_pwms(chip->npwm);
if (ret < 0)
goto out;
chip->base = ret;
chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
if (!chip->pwms) {
ret = -ENOMEM;
goto out;
}
for (i = 0; i < chip->npwm; i++) {
pwm = &chip->pwms[i];
pwm->chip = chip;
pwm->pwm = chip->base + i;
pwm->hwpwm = i;
radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
}
bitmap_set(allocated_pwms, chip->base, chip->npwm);
INIT_LIST_HEAD(&chip->list);
list_add(&chip->list, &pwm_chips);
ret = 0;
if (IS_ENABLED(CONFIG_OF))
of_pwmchip_add(chip);
out:
mutex_unlock(&pwm_lock);
if (!ret)
pwmchip_sysfs_export(chip);
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_add);
/**
* pwmchip_remove() - remove a PWM chip
* @chip: the PWM chip to remove
*
* Removes a PWM chip. This function may return busy if the PWM chip provides
* a PWM device that is still requested.
*
* Returns: 0 on success or a negative error code on failure.
*/
void pwmchip_remove(struct pwm_chip *chip)
{
pwmchip_sysfs_unexport(chip);
mutex_lock(&pwm_lock);
list_del_init(&chip->list);
if (IS_ENABLED(CONFIG_OF))
of_pwmchip_remove(chip);
free_pwms(chip);
mutex_unlock(&pwm_lock);
}
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)
{
int ret;
ret = pwmchip_add(chip);
if (ret)
return ret;
return devm_add_action_or_reset(dev, devm_pwmchip_remove, chip);
}
EXPORT_SYMBOL_GPL(devm_pwmchip_add);
/**
* pwm_request() - request a PWM device
* @pwm: global PWM device index
* @label: PWM device label
*
* This function is deprecated, use pwm_get() instead.
*
* Returns: A pointer to a PWM device or an ERR_PTR()-encoded error code on
* failure.
*/
struct pwm_device *pwm_request(int pwm, const char *label)
{
struct pwm_device *dev;
int err;
if (pwm < 0 || pwm >= MAX_PWMS)
return ERR_PTR(-EINVAL);
mutex_lock(&pwm_lock);
dev = pwm_to_device(pwm);
if (!dev) {
dev = ERR_PTR(-EPROBE_DEFER);
goto out;
}
err = pwm_device_request(dev, label);
if (err < 0)
dev = ERR_PTR(err);
out:
mutex_unlock(&pwm_lock);
return dev;
}
EXPORT_SYMBOL_GPL(pwm_request);
/**
* 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);
/**
* pwm_free() - free a PWM device
* @pwm: PWM device
*
* This function is deprecated, use pwm_put() instead.
*/
void pwm_free(struct pwm_device *pwm)
{
pwm_put(pwm);
}
EXPORT_SYMBOL_GPL(pwm_free);
static void pwm_apply_state_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, s2;
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.
*/
chip->ops->get_state(chip, pwm, &s1);
trace_pwm_get(pwm, &s1);
/*
* 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);
if (err) {
*last = s1;
dev_err(chip->dev, "failed to reapply current setting\n");
return;
}
trace_pwm_apply(pwm, &s1);
chip->ops->get_state(chip, pwm, last);
trace_pwm_get(pwm, last);
/* 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);
}
}
static int pwm_apply_legacy(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
struct pwm_state initial_state = pwm->state;
if (state->polarity != pwm->state.polarity) {
if (!chip->ops->set_polarity)
return -EINVAL;
/*
* Changing the polarity of a running PWM is only allowed when
* the PWM driver implements ->apply().
*/
if (pwm->state.enabled) {
chip->ops->disable(chip, pwm);
/*
* Update pwm->state already here in case
* .set_polarity() or another callback depend on that.
*/
pwm->state.enabled = false;
}
err = chip->ops->set_polarity(chip, pwm, state->polarity);
if (err)
goto rollback;
pwm->state.polarity = state->polarity;
}
if (!state->enabled) {
if (pwm->state.enabled)
chip->ops->disable(chip, pwm);
return 0;
}
/*
* We cannot skip calling ->config even if state->period ==
* pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
* because we might have exited early in the last call to
* pwm_apply_state because of !state->enabled and so the two values in
* pwm->state might not be configured in hardware.
*/
err = chip->ops->config(pwm->chip, pwm,
state->duty_cycle,
state->period);
if (err)
goto rollback;
pwm->state.period = state->period;
pwm->state.duty_cycle = state->duty_cycle;
if (!pwm->state.enabled) {
err = chip->ops->enable(chip, pwm);
if (err)
goto rollback;
}
return 0;
rollback:
pwm->state = initial_state;
return err;
}
/**
* pwm_apply_state() - atomically apply a new state to a PWM device
* @pwm: PWM device
* @state: new state to apply
*/
int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
{
struct pwm_chip *chip;
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_state() from atomic context
* is a bad idea. So make it explicit that calling this function might
* sleep.
*/
might_sleep();
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;
if (chip->ops->apply)
err = chip->ops->apply(chip, pwm, state);
else
err = pwm_apply_legacy(chip, pwm, state);
if (err)
return err;
trace_pwm_apply(pwm, state);
pwm->state = *state;
/*
* only do this after pwm->state was applied as some
* implementations of .get_state depend on this
*/
pwm_apply_state_debug(pwm, state);
return 0;
}
EXPORT_SYMBOL_GPL(pwm_apply_state);
/**
* 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_state(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_state(pwm, &state);
}
EXPORT_SYMBOL_GPL(pwm_adjust_config);
static struct pwm_chip *fwnode_to_pwmchip(struct fwnode_handle *fwnode)
{
struct pwm_chip *chip;
mutex_lock(&pwm_lock);
list_for_each_entry(chip, &pwm_chips, list)
if (chip->dev && dev_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.
*/
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 *pc;
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);
}
pc = fwnode_to_pwmchip(of_fwnode_handle(args.np));
if (IS_ERR(pc)) {
if (PTR_ERR(pc) != -EPROBE_DEFER)
pr_err("%s(): PWM chip not found\n", __func__);
pwm = ERR_CAST(pc);
goto put;
}
pwm = pc->of_xlate(pc, &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_free(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;
}
EXPORT_SYMBOL_GPL(of_pwm_get);
/**
* 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)