[PATCH v5 2/6] mfd: Add Rockchip mfpwm driver
Nicolas Frattaroli
nicolas.frattaroli at collabora.com
Wed May 20 08:38:41 PDT 2026
Hi Lee,
I'll respond to some points raised in-line. If I don't respond to
something, you can assume that I agree with the point with no further
comments, and will rectify in the next revision.
On Thursday, 14 May 2026 13:41:04 Central European Summer Time Lee Jones wrote:
> On Mon, 20 Apr 2026, Nicolas Frattaroli wrote:
>
> > With the Rockchip RK3576, the PWM IP used by Rockchip has changed
> > substantially. Looking at both the downstream pwm-rockchip driver as
> > well as the mainline pwm-rockchip driver made it clear that with all its
> > additional features and its differences from previous IP revisions, it
> > is best supported in a new driver.
> >
> > This brings us to the question as to what such a new driver should be.
> > To me, it soon became clear that it should actually be several new
> > drivers, most prominently when Uwe Kleine-König let me know that I
> > should not implement the pwm subsystem's capture callback, but instead
> > write a counter driver for this functionality.
> >
> > Combined with the other as-of-yet unimplemented functionality of this
> > new IP, it became apparent that it needs to be spread across several
> > subsystems.
> >
> > For this reason, we add a new MFD core driver, called mfpwm (short for
> > "Multi-function PWM"). This "parent" driver makes sure that only one
> > device function driver is using the device at a time, and is in charge
> > of registering the MFD cell devices for the individual device functions
> > offered by the device.
> >
> > An acquire/release pattern is used to guarantee that device function
> > drivers don't step on each other's toes.
>
> The whys, whos and wherefors should not be included in the commit
> message. We want to know what you're trying to achieve, why you're
> trying to achieve it and how you're going about it. This should be
> purely technical. Leave all of the conversation history out of it.
>
> I'll be honest. All of this bespoke acquisition handling is freaking me
> out. It's almost certainly not going to accepted like this, but in
> order to help suggest an alternative I need to understand exactly what
> the specifications are.
The hardware documentation is available in chapter 31 of
https://opensource.rock-chips.com/images/3/36/Rockchip_RK3506_TRM_Part_1_V1.2-20250811.pdf
which is also linked to in the PWM output driver.
The hardware itself shares a few resources among device functions
that require us to guarantee mutual exclusivity for several operations.
The resources in questions are the current operating mode (including the
enable register), and the PWM clock's rate. Additionally, an
mfpwm_acquire/release will also take care of the bus clock, which needs
to be on for register access, and have its enables/disables balanced.
The acquire/release pattern guarantees mutual exclusivity for these
resources with reentrancy. This means an individual PWM function driver
instance may re-acquire mfpwm even while it's already holding it, but
it has to release it the same number of times. This prevents any racey
"am I already holding this?" checks, because every entry point can just
acquire without worrying about whether the resource is already held by
another part of the same driver instance, as long as it balances the
calls.
I'm not sure which already existing kernel concurrency mechanism would
be suitable for replacing this. Semaphores don't track the owner,
mutexes are non-reentrant and also don't track the owner, and while the
ww_mutex could potentially be used for this, the backoff mechanism seems
a bit overblown for what we're trying to achieve here.
>
> > Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli at collabora.com>
> > ---
> > MAINTAINERS | 2 +
> > drivers/mfd/Kconfig | 16 ++
> > drivers/mfd/Makefile | 1 +
> > drivers/mfd/rockchip-mfpwm.c | 357 ++++++++++++++++++++++++++++
> > include/linux/mfd/rockchip-mfpwm.h | 470 +++++++++++++++++++++++++++++++++++++
> > 5 files changed, 846 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 86f20cb563c6..d52731242a33 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -23178,6 +23178,8 @@ L: linux-rockchip at lists.infradead.org
> > L: linux-pwm at vger.kernel.org
> > S: Maintained
> > F: Documentation/devicetree/bindings/pwm/rockchip,rk3576-pwm.yaml
> > +F: drivers/mfd/rockchip-mfpwm.c
> > +F: include/linux/mfd/rockchip-mfpwm.h
> >
> > ROCKCHIP RK3568 RANDOM NUMBER GENERATOR SUPPORT
> > M: Daniel Golle <daniel at makrotopia.org>
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index 7192c9d1d268..80b4e82c4937 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -1378,6 +1378,22 @@ config MFD_RC5T583
> > Additional drivers must be enabled in order to use the
> > different functionality of the device.
> >
> > +config MFD_ROCKCHIP_MFPWM
> > + tristate "Rockchip multi-function PWM controller"
> > + depends on ARCH_ROCKCHIP || COMPILE_TEST
> > + depends on OF
> > + depends on HAS_IOMEM
> > + depends on COMMON_CLK
> > + select MFD_CORE
> > + help
> > + Some Rockchip SoCs, such as the RK3576, use a PWM controller that has
> > + several different functions, such as generating PWM waveforms but also
> > + counting waveforms.
> > +
> > + This driver manages the overall device, and selects between different
> > + functionalities at runtime as needed. Drivers for them are implemented
> > + in their respective subsystems.
> > +
> > config MFD_RK8XX
> > tristate
> > select MFD_CORE
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index e75e8045c28a..ebadbaea9e4a 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -231,6 +231,7 @@ obj-$(CONFIG_MFD_PALMAS) += palmas.o
> > obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o
> > obj-$(CONFIG_MFD_NTXEC) += ntxec.o
> > obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o
> > +obj-$(CONFIG_MFD_ROCKCHIP_MFPWM) += rockchip-mfpwm.o
> > obj-$(CONFIG_MFD_RK8XX) += rk8xx-core.o
> > obj-$(CONFIG_MFD_RK8XX_I2C) += rk8xx-i2c.o
> > obj-$(CONFIG_MFD_RK8XX_SPI) += rk8xx-spi.o
> > diff --git a/drivers/mfd/rockchip-mfpwm.c b/drivers/mfd/rockchip-mfpwm.c
> > new file mode 100644
> > index 000000000000..72d04982b961
> > --- /dev/null
> > +++ b/drivers/mfd/rockchip-mfpwm.c
> > @@ -0,0 +1,357 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * Copyright (c) 2025 Collabora Ltd.
> > + *
> > + * A driver to manage all the different functionalities exposed by Rockchip's
> > + * PWMv4 hardware.
> > + *
> > + * This driver is chiefly focused on guaranteeing non-concurrent operation
> > + * between the different device functions, as well as setting the clocks.
> > + * It registers the device function platform devices, e.g. PWM output or
> > + * PWM capture.
> > + *
> > + * Authors:
> > + * Nicolas Frattaroli <nicolas.frattaroli at collabora.com>
> > + */
> > +
> > +#include <linux/array_size.h>
> > +#include <linux/clk.h>
> > +#include <linux/clk-provider.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/rockchip-mfpwm.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/overflow.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/spinlock.h>
> > +
> > +/**
> > + * struct rockchip_mfpwm - private mfpwm driver instance state struct
> > + * @pdev: pointer to this instance's &struct platform_device
> > + * @base: pointer to the memory mapped registers of this device
> > + * @pwm_clk: pointer to the PLL clock the PWM signal may be derived from
> > + * @osc_clk: pointer to the fixed crystal the PWM signal may be derived from
> > + * @rc_clk: pointer to the RC oscillator the PWM signal may be derived from
> > + * @chosen_clk: a clk-mux of pwm_clk, osc_clk and rc_clk
> > + * @pclk: pointer to the APB bus clock needed for mmio register access
> > + * @active_func: pointer to the currently active device function, or %NULL if no
> > + * device function is currently actively using any of the shared
> > + * resources. May only be checked/modified with @state_lock held.
> > + * @acquire_cnt: number of times @active_func has currently mfpwm_acquire()'d
> > + * it. Must only be checked or modified while holding @state_lock.
> > + * @state_lock: this lock is held while either the active device function, the
> > + * enable register, or the chosen clock is being changed.
> > + * @irq: the IRQ number of this device
> > + */
> > +struct rockchip_mfpwm {
> > + struct platform_device *pdev;
>
> It's more common to store 'struct device *'.
Yeah, I don't know what I was thinking. Looking through the places where
the pdev member is used, it pretty much always just goes for pdev->dev.
>
> > + void __iomem *base;
> > + struct clk *pwm_clk;
> > + struct clk *osc_clk;
> > + struct clk *rc_clk;
> > + struct clk *chosen_clk;
> > + struct clk *pclk;
> > + struct rockchip_mfpwm_func *active_func;
> > + unsigned int acquire_cnt;
> > + spinlock_t state_lock;
> > + int irq;
> > +};
> > +
> > +static atomic_t subdev_id = ATOMIC_INIT(0);
> > +
> > +static inline struct rockchip_mfpwm *to_rockchip_mfpwm(struct platform_device *pdev)
> > +{
> > + return platform_get_drvdata(pdev);
> > +}
>
> No pointless abstractions please. Just use the call directly.
>
> > +
> > +static int mfpwm_check_pwmf(const struct rockchip_mfpwm_func *pwmf,
> > + const char *fname)
> > +{
> > + struct device *dev = &pwmf->parent->pdev->dev;
> > +
> > + if (IS_ERR_OR_NULL(pwmf)) {
> > + dev_warn(dev, "called %s with an erroneous handle, no effect\n",
> > + fname);
>
>
>
> > + return -EINVAL;
> > + }
> > +
> > + if (IS_ERR_OR_NULL(pwmf->parent)) {
> > + dev_warn(dev, "called %s with an erroneous mfpwm_func parent, no effect\n",
> > + fname);
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +__attribute__((nonnull))
> > +static int mfpwm_do_acquire(struct rockchip_mfpwm_func *pwmf)
> > +{
> > + struct rockchip_mfpwm *mfpwm = pwmf->parent;
> > + unsigned int cnt;
> > +
> > + if (mfpwm->active_func && pwmf->id != mfpwm->active_func->id)
>
> Comments throughout please.
>
> > + return -EBUSY;
> > +
> > + if (!mfpwm->active_func)
> > + mfpwm->active_func = pwmf;
> > +
> > + if (!check_add_overflow(mfpwm->acquire_cnt, 1, &cnt)) {
> > + mfpwm->acquire_cnt = cnt;
> > + } else {
> > + dev_warn(&mfpwm->pdev->dev, "prevented acquire counter overflow in %s\n",
> > + __func__);
>
> __func__s are not user friendly. The user does not care about internals.
>
> Keep them in your local BSP if you need them.
There's no local BSP, this is a from-scratch mainline driver and I am
always running mainline.
>
> > + return -EOVERFLOW;
>
> How many are you planning to allow?
I want to ensure that even if there is a resource leakage bug, it
can't be abused in some way.
>
> > + }
> > +
> > + dev_dbg(&mfpwm->pdev->dev, "%d acquired mfpwm, acquires now at %u\n",
> > + pwmf->id, mfpwm->acquire_cnt);
>
> Drop the debug prints when upstreaming.
Again, new driver just for upstream, so it was a deliberate choice by
me to implement these to aid in debugging new drivers for the various
other functions of this hardware. I'll remove them though if this is a
requirement.
>
> > +
> > + return clk_enable(mfpwm->pclk);
> > +}
> > +
> > +int mfpwm_acquire(struct rockchip_mfpwm_func *pwmf)
> > +{
> > + struct rockchip_mfpwm *mfpwm;
> > + unsigned long flags;
> > + int ret = 0;
> > +
> > + ret = mfpwm_check_pwmf(pwmf, "mfpwm_acquire");
> > + if (ret)
> > + return ret;
> > +
> > + mfpwm = pwmf->parent;
> > + dev_dbg(&mfpwm->pdev->dev, "%d is attempting to acquire\n", pwmf->id);
> > +
> > + if (!spin_trylock_irqsave(&mfpwm->state_lock, flags))
> > + return -EBUSY;
> > +
> > + ret = mfpwm_do_acquire(pwmf);
> > +
> > + spin_unlock_irqrestore(&mfpwm->state_lock, flags);
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_NS_GPL(mfpwm_acquire, "ROCKCHIP_MFPWM");
> > +
> > +__attribute__((nonnull))
> > +static void mfpwm_do_release(const struct rockchip_mfpwm_func *pwmf)
> > +{
> > + struct rockchip_mfpwm *mfpwm = pwmf->parent;
> > +
> > + if (!mfpwm->active_func)
> > + return;
> > +
> > + if (mfpwm->active_func->id != pwmf->id)
> > + return;
> > +
> > + /*
> > + * No need to check_sub_overflow here, !mfpwm->active_func above catches
> > + * this type of problem already.
> > + */
> > + mfpwm->acquire_cnt--;
> > +
> > + if (!mfpwm->acquire_cnt)
> > + mfpwm->active_func = NULL;
> > +
> > + clk_disable(mfpwm->pclk);
> > +}
> > +
> > +void mfpwm_release(const struct rockchip_mfpwm_func *pwmf)
> > +{
> > + struct rockchip_mfpwm *mfpwm;
> > + unsigned long flags;
> > +
> > + if (mfpwm_check_pwmf(pwmf, "mfpwm_release"))
> > + return;
> > +
> > + mfpwm = pwmf->parent;
> > +
> > + spin_lock_irqsave(&mfpwm->state_lock, flags);
> > + mfpwm_do_release(pwmf);
> > + dev_dbg(&mfpwm->pdev->dev, "%d released mfpwm, acquires now at %u\n",
> > + pwmf->id, mfpwm->acquire_cnt);
> > + spin_unlock_irqrestore(&mfpwm->state_lock, flags);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(mfpwm_release, "ROCKCHIP_MFPWM");
> > +
> > +int mfpwm_get_mode(const struct rockchip_mfpwm_func *pwmf)
> > +{
> > + struct rockchip_mfpwm *mfpwm;
> > + int ret;
> > +
> > + ret = mfpwm_check_pwmf(pwmf, "mfpwm_acquire");
> > + if (ret)
> > + return ret;
> > +
> > + mfpwm = pwmf->parent;
> > +
> > + guard(spinlock_irqsave)(&mfpwm->state_lock);
> > +
> > + if (!rockchip_pwm_v4_is_enabled(mfpwm_reg_read(mfpwm->base, PWMV4_REG_ENABLE)))
>
> Don't embed function names like this.
I don't understand this review. Is the name "rockchip_pwm_v4_is_enabled"
not okay? Is chaining two functions together like this not okay?
>
> > + return -1;
>
> -1 is not a real error code.
>
> > +
> > + return mfpwm_reg_read(mfpwm->base, PWMV4_REG_CTRL) & PWMV4_MODE_MASK;
> > +}
> > +EXPORT_SYMBOL_NS_GPL(mfpwm_get_mode, "ROCKCHIP_MFPWM");
> > +
> > +/**
> > + * mfpwm_register_subdev - register a single mfpwm_func
> > + * @mfpwm: pointer to the parent &struct rockchip_mfpwm
> > + * @name: sub-device name string
> > + *
> > + * Allocate a single &struct mfpwm_func, fill its members with appropriate data,
> > + * and register a new mfd cell.
> > + *
> > + * Returns: 0 on success, negative errno on error
> > + */
> > +static int mfpwm_register_subdev(struct rockchip_mfpwm *mfpwm,
> > + const char *name)
> > +{
> > + struct rockchip_mfpwm_func *func;
> > + struct mfd_cell cell = {};
> > +
> > + func = devm_kzalloc(&mfpwm->pdev->dev, sizeof(*func), GFP_KERNEL);
> > + if (IS_ERR(func))
> > + return PTR_ERR(func);
> > + func->irq = mfpwm->irq;
> > + func->parent = mfpwm;
>
> Suggest you use the 'struct device' hierarchy instead of hand rolling
> your own.
>
> > + func->id = atomic_inc_return(&subdev_id);
>
> Why dosen't PLATFORM_DEVID_AUTO work for you?
It probably will, I just didn't know about it.
> > + func->base = mfpwm->base;
> > + func->core = mfpwm->chosen_clk;
> > + cell.name = name;
> > + cell.platform_data = func;
> > + cell.pdata_size = sizeof(*func);
> > +
> > + return devm_mfd_add_devices(&mfpwm->pdev->dev, func->id, &cell, 1, NULL,
> > + 0, NULL);
> > +}
> > +
> > +static int mfpwm_register_subdevs(struct rockchip_mfpwm *mfpwm)
> > +{
> > + int ret;
> > +
> > + ret = mfpwm_register_subdev(mfpwm, "rockchip-pwm-v4");
> > + if (ret)
> > + return ret;
> > +
> > + ret = mfpwm_register_subdev(mfpwm, "rockchip-pwm-capture");
> > + if (ret)
> > + return ret;
> > +
> > + return 0;
> > +}
>
> Place all of your devices in static (const if they are immutable)
> structs. Literally no one else does MFD registration like this - do not
> reinvent the wheel.
>
> > +static int rockchip_mfpwm_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct rockchip_mfpwm *mfpwm;
>
> Could we use 'ddata' for the variable instance name instead of 'mfpwm'
> to follow standard naming conventions for private data structures?
>
> > + char *clk_mux_name;
> > + const char *mux_p_names[3];
> > + int ret = 0;
> > +
> > + mfpwm = devm_kzalloc(&pdev->dev, sizeof(*mfpwm), GFP_KERNEL);
> > + if (IS_ERR(mfpwm))
> > + return PTR_ERR(mfpwm);
> > +
> > + mfpwm->pdev = pdev;
> > +
> > + spin_lock_init(&mfpwm->state_lock);
> > +
> > + mfpwm->base = devm_platform_ioremap_resource(pdev, 0);
> > + if (IS_ERR(mfpwm->base))
> > + return dev_err_probe(dev, PTR_ERR(mfpwm->base),
> > + "failed to ioremap address\n");
>
> Doesn't devm_platform_ioremap_resource() already have its own error messages?
>
> > +
> > + mfpwm->pclk = devm_clk_get_prepared(dev, "pclk");
> > + if (IS_ERR(mfpwm->pclk))
> > + return dev_err_probe(dev, PTR_ERR(mfpwm->pclk),
> > + "couldn't get and prepare 'pclk' clock\n");
> > +
> > + mfpwm->irq = platform_get_irq(pdev, 0);
> > + if (mfpwm->irq < 0)
> > + return dev_err_probe(dev, mfpwm->irq, "couldn't get irq 0\n");
> > +
> > + mfpwm->pwm_clk = devm_clk_get_prepared(dev, "pwm");
> > + if (IS_ERR(mfpwm->pwm_clk))
> > + return dev_err_probe(dev, PTR_ERR(mfpwm->pwm_clk),
> > + "couldn't get and prepare 'pwm' clock\n");
> > +
> > + mfpwm->osc_clk = devm_clk_get_prepared(dev, "osc");
> > + if (IS_ERR(mfpwm->osc_clk))
> > + return dev_err_probe(dev, PTR_ERR(mfpwm->osc_clk),
> > + "couldn't get and prepare 'osc' clock\n");
> > +
> > + mfpwm->rc_clk = devm_clk_get_prepared(dev, "rc");
> > + if (IS_ERR(mfpwm->rc_clk))
> > + return dev_err_probe(dev, PTR_ERR(mfpwm->rc_clk),
> > + "couldn't get and prepare 'rc' clock\n");
> > +
>
> I'd do these in a loop.
>
> > + clk_mux_name = devm_kasprintf(dev, GFP_KERNEL, "%s_chosen", dev_name(dev));
> > + if (!clk_mux_name)
> > + return -ENOMEM;
> > +
> > + mux_p_names[0] = __clk_get_name(mfpwm->pwm_clk);
> > + mux_p_names[1] = __clk_get_name(mfpwm->osc_clk);
> > + mux_p_names[2] = __clk_get_name(mfpwm->rc_clk);
>
> Didn't you already request these by name?
I requested them based on the name they have in this device's device tree
node's clock-names property, which is not the same as the common clock
framework's global name for this particular clock.
>
> > + mfpwm->chosen_clk = clk_register_mux(dev, clk_mux_name, mux_p_names,
>
> devm_clk_hw_register_mux()?
I'll need to double-check whether using a clk_hw->clk has the same
semantics here, but I agree that this should use a devres helper.
>
> > + ARRAY_SIZE(mux_p_names),
> > + CLK_SET_RATE_PARENT,
> > + mfpwm->base + PWMV4_REG_CLK_CTRL,
> > + PWMV4_CLK_SRC_SHIFT, PWMV4_CLK_SRC_WIDTH,
> > + CLK_MUX_HIWORD_MASK, NULL);
> > + ret = clk_prepare(mfpwm->chosen_clk);
> > + if (ret) {
> > + dev_err(dev, "failed to prepare PWM clock mux: %pe\n",
> > + ERR_PTR(ret));
>
> dev_err_probe()
>
> > + return ret;
> > + }
> > +
> > + platform_set_drvdata(pdev, mfpwm);
> > +
> > + ret = mfpwm_register_subdevs(mfpwm);
> > + if (ret) {
> > + dev_err(dev, "failed to register sub-devices: %pe\n",
> > + ERR_PTR(ret));
>
> * Should we use 'dev_err_probe()' for this error path as well to correctly
> handle deferred probing?
>
> > + return ret;
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static void rockchip_mfpwm_remove(struct platform_device *pdev)
> > +{
> > + struct rockchip_mfpwm *mfpwm = to_rockchip_mfpwm(pdev);
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&mfpwm->state_lock, flags);
> > +
> > + if (mfpwm->chosen_clk) {
> > + clk_unprepare(mfpwm->chosen_clk);
>
> No devm_* version available?
The common clock framework does not have devres helpers for prepare
and unprepare (or enable and disable, for that matter). But I'd like
to avoid another sidequest to implement those after I've already been
on a sidequest spawned by this series to add bitfield_hw.h.
>
> > + clk_unregister_mux(mfpwm->chosen_clk);
> > + }
> > +
> > + spin_unlock_irqrestore(&mfpwm->state_lock, flags);
> > +}
> > +
> > +static const struct of_device_id rockchip_mfpwm_of_match[] = {
> > + {
> > + .compatible = "rockchip,rk3576-pwm",
> > + },
>
> Single line.
>
> > + { /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, rockchip_mfpwm_of_match);
> > +
> > +static struct platform_driver rockchip_mfpwm_driver = {
> > + .driver = {
> > + .name = KBUILD_MODNAME,
>
> Use the raw string instead - this makes debugging challenging.
>
> > + .of_match_table = rockchip_mfpwm_of_match,
> > + },
> > + .probe = rockchip_mfpwm_probe,
> > + .remove = rockchip_mfpwm_remove,
> > +};
> > +module_platform_driver(rockchip_mfpwm_driver);
> > +
> > +MODULE_AUTHOR("Nicolas Frattaroli <nicolas.frattaroli at collabora.com>");
> > +MODULE_DESCRIPTION("Rockchip MFPWM Driver");
>
> FWIW, I don't like the name.
That's the name my parents gave me, I can't help it. :(
>
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mfd/rockchip-mfpwm.h b/include/linux/mfd/rockchip-mfpwm.h
>
> How much of this file is applicable to the core driver?
Just REG_ENABLE/REG_CTRL and rockchip_mfpwm_func. The register
definitions do need to live somewhere shared though. Is there a
problem with making it part of the rockchip-mfpwm.h header? If so,
what would a more appropriate place be, if I want to make all 3
drivers use the same header file for it?
>
> > new file mode 100644
> > index 000000000000..dbf1588a4382
> > --- /dev/null
> > +++ b/include/linux/mfd/rockchip-mfpwm.h
> > @@ -0,0 +1,470 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +/*
> > + * Copyright (c) 2025 Collabora Ltd.
> > + *
> > + * Common header file for all the Rockchip Multi-function PWM controller
> > + * drivers that are spread across subsystems.
> > + *
> > + * Authors:
> > + * Nicolas Frattaroli <nicolas.frattaroli at collabora.com>
> > + */
> > +
> > +#ifndef __SOC_ROCKCHIP_MFPWM_H__
> > +#define __SOC_ROCKCHIP_MFPWM_H__
> > +
> > +#include <linux/bits.h>
> > +#include <linux/clk.h>
> > +#include <linux/hw_bitfield.h>
> > +#include <linux/io.h>
> > +#include <linux/spinlock.h>
> > +
> > +struct rockchip_mfpwm;
> > +
> > +/**
> > + * struct rockchip_mfpwm_func - struct representing a single function driver
> > + *
> > + * @id: unique id for this function driver instance
> > + * @base: pointer to start of MMIO registers
> > + * @parent: a pointer to the parent mfpwm struct
> > + * @irq: the shared IRQ gotten from the parent mfpwm device
> > + * @core: a pointer to the clk mux that drives this channel's PWM
> > + */
> > +struct rockchip_mfpwm_func {
> > + int id;
> > + void __iomem *base;
> > + struct rockchip_mfpwm *parent;
> > + int irq;
> > + struct clk *core;
> > +};
> > +
> > +/*
> > + * PWMV4 Register Definitions
> > + * --------------------------
> > + *
> > + * Attributes:
> > + * RW - Read-Write
> > + * RO - Read-Only
> > + * WO - Write-Only
> > + * W1T - Write high, Self-clearing
> > + * W1C - Write high to clear interrupt
> > + *
> > + * Bit ranges to be understood with Verilog-like semantics,
> > + * e.g. [03:00] is 4 bits: 0, 1, 2 and 3.
> > + *
> > + * All registers must be accessed with 32-bit width accesses only
> > + */
> > +
> > +#define PWMV4_REG_VERSION 0x000
> > +/*
> > + * VERSION Register Description
> > + * [31:24] RO | Hardware Major Version
> > + * [23:16] RO | Hardware Minor Version
> > + * [15:15] RO | Reserved
> > + * [14:14] RO | Hardware supports biphasic counters
> > + * [13:13] RO | Hardware supports filters
> > + * [12:12] RO | Hardware supports waveform generation
> > + * [11:11] RO | Hardware supports counter
> > + * [10:10] RO | Hardware supports frequency metering
> > + * [09:09] RO | Hardware supports power key functionality
> > + * [08:08] RO | Hardware supports infrared transmissions
> > + * [07:04] RO | Channel index of this instance
> > + * [03:00] RO | Number of channels the base instance supports
> > + */
> > +
> > +#define PWMV4_REG_ENABLE 0x004
> > +/*
> > + * ENABLE Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:06] RO | Reserved
> > + * [05:05] RW | PWM Channel Counter Read Enable, 1 = enabled
> > + */
> > +#define PWMV4_CHN_CNT_RD_EN(v) FIELD_PREP_WM16(BIT(5), (v))
> > +/*
> > + * [04:04] W1T | PWM Globally Joined Control Enable
> > + * 1 = this PWM channel will be enabled by a global pwm enable
> > + * bit instead of the PWM Enable bit.
> > + */
> > +#define PWMV4_GLOBAL_CTRL_EN(v) FIELD_PREP_WM16(BIT(4), (v))
> > +/*
> > + * [03:03] RW | Force Clock Enable
> > + * 0 = disabled, if the PWM channel is inactive then so is the
> > + * clock prescale module
> > + */
> > +#define PWMV4_FORCE_CLK_EN(v) FIELD_PREP_WM16(BIT(3), (v))
> > +/*
> > + * [02:02] W1T | PWM Control Update Enable
> > + * 1 = enabled, commits modifications of _CTRL, _PERIOD, _DUTY and
> > + * _OFFSET registers once 1 is written to it
> > + */
> > +#define PWMV4_CTRL_UPDATE_EN FIELD_PREP_WM16_CONST(BIT(2), 1)
> > +/*
> > + * [01:01] RW | PWM Enable, 1 = enabled
> > + * If in one-shot mode, clears after end of operation
> > + */
> > +#define PWMV4_EN_MASK BIT(1)
> > +#define PWMV4_EN(v) FIELD_PREP_WM16(PWMV4_EN_MASK, \
> > + ((v) ? 1 : 0))
> > +/*
> > + * [00:00] RW | PWM Clock Enable, 1 = enabled
> > + * If in one-shot mode, clears after end of operation
> > + */
> > +#define PWMV4_CLK_EN_MASK BIT(0)
> > +#define PWMV4_CLK_EN(v) FIELD_PREP_WM16(PWMV4_CLK_EN_MASK, \
> > + ((v) ? 1 : 0))
> > +#define PWMV4_EN_BOTH_MASK (PWMV4_EN_MASK | PWMV4_CLK_EN_MASK)
> > +static inline __pure bool rockchip_pwm_v4_is_enabled(unsigned int val)
> > +{
> > + return (val & PWMV4_EN_BOTH_MASK);
> > +}
> > +
> > +#define PWMV4_REG_CLK_CTRL 0x008
> > +/*
> > + * CLK_CTRL Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:15] RW | Clock Global Selection
> > + * 0 = current channel scale clock
> > + * 1 = global channel scale clock
> > + */
> > +#define PWMV4_CLK_GLOBAL(v) FIELD_PREP_WM16(BIT(15), (v))
> > +/*
> > + * [14:13] RW | Clock Source Selection
> > + * 0 = Clock from PLL, frequency can be configured
> > + * 1 = Clock from crystal oscillator, frequency is fixed
> > + * 2 = Clock from RC oscillator, frequency is fixed
> > + * 3 = Reserved
> > + * NOTE: The purpose for this clock-mux-outside-CRU construct is
> > + * to let the SoC go into a sleep state with the PWM
> > + * hardware still having a clock signal for IR input, which
> > + * can then wake up the SoC.
> > + */
> > +#define PWMV4_CLK_SRC_PLL 0x0U
> > +#define PWMV4_CLK_SRC_CRYSTAL 0x1U
> > +#define PWMV4_CLK_SRC_RC 0x2U
> > +#define PWMV4_CLK_SRC_SHIFT 13
> > +#define PWMV4_CLK_SRC_WIDTH 2
> > +/*
> > + * [12:04] RW | Scale Factor to apply to pre-scaled clock
> > + * 1 <= v <= 256, v means clock divided by 2*v
> > + */
> > +#define PWMV4_CLK_SCALE_F(v) FIELD_PREP_WM16(GENMASK(12, 4), (v))
> > +/*
> > + * [03:03] RO | Reserved
> > + * [02:00] RW | Prescale Factor
> > + * v here means the input clock is divided by pow(2, v)
> > + */
> > +#define PWMV4_CLK_PRESCALE_F(v) FIELD_PREP_WM16(GENMASK(2, 0), (v))
> > +
> > +#define PWMV4_REG_CTRL 0x00C
> > +/*
> > + * CTRL Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:09] RO | Reserved
> > + * [08:06] RW | PWM Input Channel Selection
> > + * By default, the channel selects its own input, but writing v
> > + * here selects PWM input from channel v instead.
> > + */
> > +#define PWMV4_CTRL_IN_SEL(v) FIELD_PREP_WM16(GENMASK(8, 6), (v))
> > +/* [05:05] RW | Aligned Mode, 0 = Valid, 1 = Invalid */
> > +#define PWMV4_CTRL_UNALIGNED(v) FIELD_PREP_WM16(BIT(5), (v))
> > +/* [04:04] RW | Output Mode, 0 = Left Aligned, 1 = Centre Aligned */
> > +#define PWMV4_LEFT_ALIGNED 0x0U
> > +#define PWMV4_CENTRE_ALIGNED 0x1U
> > +#define PWMV4_CTRL_OUT_MODE(v) FIELD_PREP_WM16(BIT(4), (v))
> > +/*
> > + * [03:03] RW | Inactive Polarity for when the channel is either disabled or
> > + * has completed outputting the entire waveform in one-shot mode.
> > + * 0 = Negative, 1 = Positive
> > + */
> > +#define PWMV4_POLARITY_N 0x0U
> > +#define PWMV4_POLARITY_P 0x1U
> > +#define PWMV4_INACTIVE_POL(v) FIELD_PREP_WM16(BIT(3), (v))
> > +/*
> > + * [02:02] RW | Duty Cycle Polarity to use at the start of the waveform.
> > + * 0 = Negative, 1 = Positive
> > + */
> > +#define PWMV4_DUTY_POL_SHIFT 2
> > +#define PWMV4_DUTY_POL_MASK BIT(PWMV4_DUTY_POL_SHIFT)
> > +#define PWMV4_DUTY_POL(v) FIELD_PREP_WM16(PWMV4_DUTY_POL_MASK, \
> > + (v))
> > +/*
> > + * [01:00] RW | PWM Mode
> > + * 0 = One-shot mode, PWM generates waveform RPT times
> > + * 1 = Continuous mode
> > + * 2 = Capture mode, PWM measures cycles of input waveform
> > + * 3 = Reserved
> > + */
> > +#define PWMV4_MODE_ONESHOT 0x0U
> > +#define PWMV4_MODE_CONT 0x1U
> > +#define PWMV4_MODE_CAPTURE 0x2U
> > +#define PWMV4_MODE_MASK GENMASK(1, 0)
> > +#define PWMV4_MODE(v) FIELD_PREP_WM16(PWMV4_MODE_MASK, (v))
> > +#define PWMV4_CTRL_COM_FLAGS (PWMV4_INACTIVE_POL(PWMV4_POLARITY_N) | \
> > + PWMV4_DUTY_POL(PWMV4_POLARITY_P) | \
> > + PWMV4_CTRL_OUT_MODE(PWMV4_LEFT_ALIGNED) | \
> > + PWMV4_CTRL_UNALIGNED(true))
> > +#define PWMV4_CTRL_CONT_FLAGS (PWMV4_MODE(PWMV4_MODE_CONT) | \
> > + PWMV4_CTRL_COM_FLAGS)
> > +#define PWMV4_CTRL_CAP_FLAGS (PWMV4_MODE(PWMV4_MODE_CAPTURE) | \
> > + PWMV4_CTRL_COM_FLAGS)
> > +
> > +#define PWMV4_REG_PERIOD 0x010
> > +/*
> > + * PERIOD Register Description
> > + * [31:00] RW | Period of the output waveform
> > + * Constraints: should be even if CTRL_OUT_MODE is CENTRE_ALIGNED
> > + */
> > +
> > +#define PWMV4_REG_DUTY 0x014
> > +/*
> > + * DUTY Register Description
> > + * [31:00] RW | Duty cycle of the output waveform
> > + * Constraints: should be even if CTRL_OUT_MODE is CENTRE_ALIGNED
> > + */
> > +
> > +#define PWMV4_REG_OFFSET 0x018
> > +/*
> > + * OFFSET Register Description
> > + * [31:00] RW | Offset of the output waveform, based on the PWM clock
> > + * Constraints: 0 <= v <= (PERIOD - DUTY)
> > + */
> > +
> > +#define PWMV4_REG_RPT 0x01C
> > +/*
> > + * RPT Register Description
> > + * [31:16] RW | Second dimensional of the effective number of waveform
> > + * repetitions. Increases by one every first dimensional times.
> > + * Value `n` means `n + 1` repetitions. The final number of
> > + * repetitions of the waveform in one-shot mode is:
> > + * `(first_dimensional + 1) * (second_dimensional + 1)`
> > + * [15:00] RW | First dimensional of the effective number of waveform
> > + * repetitions. Value `n` means `n + 1` repetitions.
> > + */
> > +
> > +#define PWMV4_REG_FILTER_CTRL 0x020
> > +/*
> > + * FILTER_CTRL Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:10] RO | Reserved
> > + * [09:04] RW | Filter window number
> > + * [03:01] RO | Reserved
> > + * [00:00] RW | Filter Enable, 0 = disabled, 1 = enabled
> > + */
> > +
> > +#define PWMV4_REG_CNT 0x024
> > +/*
> > + * CNT Register Description
> > + * [31:00] RO | Current value of the PWM Channel 0 counter in pwm clock cycles,
> > + * 0 <= v <= 2^32-1
> > + */
> > +
> > +#define PWMV4_REG_ENABLE_DELAY 0x028
> > +/*
> > + * ENABLE_DELAY Register Description
> > + * [31:16] RO | Reserved
> > + * [15:00] RW | PWM enable delay, in an unknown unit but probably cycles
> > + */
> > +
> > +#define PWMV4_REG_HPC 0x02C
> > +/*
> > + * HPC Register Description
> > + * [31:00] RW | Number of effective high polarity cycles of the input waveform
> > + * in capture mode. Based on the PWM clock. 0 <= v <= 2^32-1
> > + */
> > +
> > +#define PWMV4_REG_LPC 0x030
> > +/*
> > + * LPC Register Description
> > + * [31:00] RW | Number of effective low polarity cycles of the input waveform
> > + * in capture mode. Based on the PWM clock. 0 <= v <= 2^32-1
> > + */
> > +
> > +#define PWMV4_REG_BIPHASIC_CNT_CTRL0 0x040
> > +/*
> > + * BIPHASIC_CNT_CTRL0 Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:10] RO | Reserved
> > + * [09:09] RW | Biphasic Counter Phase Edge Selection for mode 0,
> > + * 0 = rising edge (posedge), 1 = falling edge (negedge)
> > + * [08:08] RW | Biphasic Counter Clock force enable, 1 = force enable
> > + * [07:07] W1T | Synchronous Enable
> > + * [06:06] W1T | Mode Switch
> > + * 0 = Normal Mode, 1 = Switch timer clock and measured clock
> > + * Constraints: "Biphasic Counter Mode" must be 0 if this is 1
> > + * [05:03] RW | Biphasic Counter Mode
> > + * 0x0 = Mode 0, 0x1 = Mode 1, 0x2 = Mode 2, 0x3 = Mode 3,
> > + * 0x4 = Mode 4, 0x5 = Reserved
> > + * [02:02] RW | Biphasic Counter Clock Selection
> > + * 0 = clock is from PLL and frequency can be configured
> > + * 1 = clock is from crystal oscillator and frequency is fixed
> > + * [01:01] RW | Biphasic Counter Continuous Mode
> > + * [00:00] W1T | Biphasic Counter Enable
> > + */
> > +
> > +#define PWMV4_REG_BIPHASIC_CNT_CTRL1 0x044
> > +/*
> > + * BIPHASIC_CNT_CTRL1 Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:11] RO | Reserved
> > + * [10:04] RW | Biphasic Counter Filter Window Number
> > + * [03:01] RO | Reserved
> > + * [00:00] RW | Biphasic Counter Filter Enable
> > + */
> > +
> > +#define PWMV4_REG_BIPHASIC_CNT_TIMER 0x048
> > +/*
> > + * BIPHASIC_CNT_TIMER Register Description
> > + * [31:00] RW | Biphasic Counter Timer Value, in number of biphasic counter
> > + * timer clock cycles
> > + */
> > +
> > +#define PWMV4_REG_BIPHASIC_CNT_RES 0x04C
> > +/*
> > + * BIPHASIC_CNT_RES Register Description
> > + * [31:00] RO | Biphasic Counter Result Value
> > + * Constraints: Can only be read after INTSTS[9] is asserted
> > + */
> > +
> > +#define PWMV4_REG_BIPHASIC_CNT_RES_S 0x050
> > +/*
> > + * BIPHASIC_CNT_RES_S Register Description
> > + * [31:00] RO | Biphasic Counter Result Value with synchronised processing
> > + * Can be read in real-time if BIPHASIC_CNT_CTRL0[7] was set to 1
> > + */
> > +
> > +#define PWMV4_REG_INTSTS 0x070
> > +/*
> > + * INTSTS Register Description
> > + * [31:10] RO | Reserved
> > + * [09:09] W1C | Biphasic Counter Interrupt Status, 1 = interrupt asserted
> > + * [08:08] W1C | Waveform Middle Interrupt Status, 1 = interrupt asserted
> > + * [07:07] W1C | Waveform Max Interrupt Status, 1 = interrupt asserted
> > + * [06:06] W1C | IR Transmission End Interrupt Status, 1 = interrupt asserted
> > + * [05:05] W1C | Power Key Match Interrupt Status, 1 = interrupt asserted
> > + * [04:04] W1C | Frequency Meter Interrupt Status, 1 = interrupt asserted
> > + * [03:03] W1C | Reload Interrupt Status, 1 = interrupt asserted
> > + * [02:02] W1C | Oneshot End Interrupt Status, 1 = interrupt asserted
> > + * [01:01] W1C | HPC Capture Interrupt Status, 1 = interrupt asserted
> > + * [00:00] W1C | LPC Capture Interrupt Status, 1 = interrupt asserted
> > + */
> > +#define PWMV4_INT_LPC BIT(0)
> > +#define PWMV4_INT_HPC BIT(1)
> > +#define PWMV4_INT_LPC_W(v) FIELD_PREP_WM16(PWMV4_INT_LPC, \
> > + ((v) ? 1 : 0))
> > +#define PWMV4_INT_HPC_W(v) FIELD_PREP_WM16(PWMV4_INT_HPC, \
> > + ((v) ? 1 : 0))
> > +
> > +#define PWMV4_REG_INT_EN 0x074
> > +/*
> > + * INT_EN Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:10] RO | Reserved
> > + * [09:09] RW | Biphasic Counter Interrupt Enable, 1 = enabled
> > + * [08:08] W1C | Waveform Middle Interrupt Enable, 1 = enabled
> > + * [07:07] W1C | Waveform Max Interrupt Enable, 1 = enabled
> > + * [06:06] W1C | IR Transmission End Interrupt Enable, 1 = enabled
> > + * [05:05] W1C | Power Key Match Interrupt Enable, 1 = enabled
> > + * [04:04] W1C | Frequency Meter Interrupt Enable, 1 = enabled
> > + * [03:03] W1C | Reload Interrupt Enable, 1 = enabled
> > + * [02:02] W1C | Oneshot End Interrupt Enable, 1 = enabled
> > + * [01:01] W1C | HPC Capture Interrupt Enable, 1 = enabled
> > + * [00:00] W1C | LPC Capture Interrupt Enable, 1 = enabled
> > + */
> > +
> > +#define PWMV4_REG_INT_MASK 0x078
> > +/*
> > + * INT_MASK Register Description
> > + * [31:16] WO | Write Enable Mask for the lower half of the register
> > + * Set bit `n` here to 1 if you wish to modify bit `n >> 16` in
> > + * the same write operation
> > + * [15:10] RO | Reserved
> > + * [09:09] RW | Biphasic Counter Interrupt Masked, 1 = masked
> > + * [08:08] W1C | Waveform Middle Interrupt Masked, 1 = masked
> > + * [07:07] W1C | Waveform Max Interrupt Masked, 1 = masked
> > + * [06:06] W1C | IR Transmission End Interrupt Masked, 1 = masked
> > + * [05:05] W1C | Power Key Match Interrupt Masked, 1 = masked
> > + * [04:04] W1C | Frequency Meter Interrupt Masked, 1 = masked
> > + * [03:03] W1C | Reload Interrupt Masked, 1 = masked
> > + * [02:02] W1C | Oneshot End Interrupt Masked, 1 = masked
> > + * [01:01] W1C | HPC Capture Interrupt Masked, 1 = masked
> > + * [00:00] W1C | LPC Capture Interrupt Masked, 1 = masked
> > + */
> > +
> > +static inline u32 mfpwm_reg_read(void __iomem *base, u32 reg)
> > +{
> > + return readl(base + reg);
> > +}
> > +
> > +static inline void mfpwm_reg_write(void __iomem *base, u32 reg, u32 val)
> > +{
> > + writel(val, base + reg);
> > +}
>
> a) Please do not abstract for the sake of it.
> b) Please use Regmap instead.
I agree but a) is a useless abstraction, but I don't think b) is
any better in this case either. This is an mmio device, and mmio
regmaps are an abstraction that provide zero benefit for this device
in my opinion. No cache is needed here, and no register spinlock is
needed either as the registers use the WM16 mechanism. In fact, the
register spinlock would slap a more coarse-grained lock on top of
the fine-grained wait-free atomicity that the hardware gives us.
What they do necessitate though is that all reads are done into an
output pointer instead of a return value, because the return value
is used for communicating an error code. If I didn't ignore the error
return value (I'm pretty sure it's useless for mmio regmaps) then I
will also be doing unpleasant error unwinds in every function that
accesses registers. And, whenever I want to do
if (contents_of_register == foo)
I can't just do the read there, I need to read it into a local first
outside of the if statement, even if I just use it once.
I have, while developing this driver, used regmaps before, and decided
that they just make the code worse.
I do agree though that mfpwm_reg_read/mfpwm_reg_write seem pointless,
I think I wanted it to take an mfpwm once but then made mfpwm private.
I'll refactor stuff to get rid of these, but I won't use regmaps.
Kind regards,
Nicolas Frattaroli
>
> > +
> > +/**
> > + * mfpwm_acquire - try becoming the active mfpwm function device
> > + * @pwmf: pointer to the calling driver instance's &struct rockchip_mfpwm_func
> > + *
> > + * mfpwm device "function" drivers must call this function before doing anything
> > + * that either modifies or relies on the parent device's state, such as clocks,
> > + * enabling/disabling outputs, modifying shared regs etc.
> > + *
> > + * The return statues should always be checked.
> > + *
> > + * All mfpwm_acquire() calls must be balanced with corresponding mfpwm_release()
> > + * calls once the device is no longer making changes that affect other devices,
> > + * or stops producing user-visible effects that depend on the current device
> > + * state being kept as-is. (e.g. after the PWM output signal is stopped)
> > + *
> > + * The same device function may mfpwm_acquire() multiple times while it already
> > + * is active, i.e. it is re-entrant, though it needs to balance this with the
> > + * same number of mfpwm_release() calls.
> > + *
> > + * Context: This function does not sleep.
> > + *
> > + * Return:
> > + * * %0 - success
> > + * * %-EBUSY - a different device function is active
> > + * * %-EOVERFLOW - the acquire counter is at its maximum
> > + */
> > +extern int __must_check mfpwm_acquire(struct rockchip_mfpwm_func *pwmf);
> > +
> > +/**
> > + * mfpwm_release - drop usage of active mfpwm device function by 1
> > + * @pwmf: pointer to the calling driver instance's &struct rockchip_mfpwm_func
> > + *
> > + * This is the balancing call to mfpwm_acquire(). If no users of the device
> > + * function remain, set the mfpwm device to have no active device function,
> > + * allowing other device functions to claim it.
> > + */
> > +extern void mfpwm_release(const struct rockchip_mfpwm_func *pwmf);
> > +
> > +/**
> > + * mfpwm_get_mode - get the current mode the hardware is in
> > + * @pwmf: pointer to a &struct rockchip_mfpwm_func
> > + *
> > + * Check the hardware registers of the PWM hardware to determine which mode it
> > + * is currently operating in, if any.
> > + *
> > + * Returns:
> > + * - %-EINVAL if @pwmf is %NULL or an error pointer
> > + * - %-1 if the PWM hardware is off, regardless of operating mode
> > + * - %PWMV4_MODE_ONESHOT if PWM hardware is in one-shot output mode
> > + * - %PWMV4_MODE_CONT if PWM hardware is in continuous output mode
> > + * - %PWMV4_MODE_CAPTURE if PWM hardware is in capture mode
> > + */
> > +extern int mfpwm_get_mode(const struct rockchip_mfpwm_func *pwmf);
> > +
> > +#endif /* __SOC_ROCKCHIP_MFPWM_H__ */
> >
>
>
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