Message-ID: <AM6PR0402MB3911185E2D7E96FD3224BCBDF5410@AM6PR0402MB3911.eurprd04.prod.outlook.com>
Date:   Wed, 20 Mar 2019 10:17:50 +0000
From:   Anson Huang <anson.huang@....com>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
CC:     "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "otavio@...ystems.com.br" <otavio@...ystems.com.br>,
        "stefan@...er.ch" <stefan@...er.ch>,
        Leonard Crestez <leonard.crestez@....com>,
        "schnitzeltony@...il.com" <schnitzeltony@...il.com>,
        Robin Gong <yibin.gong@....com>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V7 2/5] pwm: Add i.MX TPM PWM driver support

Hi, Uwe

Best Regards!
Anson Huang

> -----Original Message-----
> From: Uwe Kleine-König [mailto:u.kleine-koenig@...gutronix.de]
> Sent: 2019年3月20日 16:19
> To: Anson Huang <anson.huang@....com>
> Cc: thierry.reding@...il.com; robh+dt@...nel.org; mark.rutland@....com;
> shawnguo@...nel.org; s.hauer@...gutronix.de; kernel@...gutronix.de;
> festevam@...il.com; linux@...linux.org.uk; otavio@...ystems.com.br;
> stefan@...er.ch; Leonard Crestez <leonard.crestez@....com>;
> schnitzeltony@...il.com; Robin Gong <yibin.gong@....com>; linux-
> pwm@...r.kernel.org; devicetree@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH V7 2/5] pwm: Add i.MX TPM PWM driver support
> 
> Hello,
> 
> On Wed, Mar 20, 2019 at 05:06:21AM +0000, Anson Huang wrote:
> > i.MX7ULP has TPM(Low Power Timer/Pulse Width Modulation Module)
> > inside, it can support multiple PWM channels, all the channels share
> > same counter and period setting, but each channel can configure its
> > duty and polarity independently.
> >
> > There are several TPM modules in i.MX7ULP, the number of channels in
> > TPM modules are different, it can be read from each TPM module's PARAM
> > register.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@....com>
> > ---
> > Changes since V6:
> > 	- merge "config" and "enable" functions into ONE function
> pwm_imx_tpm_apply_hw;
> > 	- save computation for confiuring counter, the "round_state"
> function will return
> > 	  the registers value directly;
> > 	- improve the logic in .apply;
> > 	- return error when there is still PWM active during suspend callback.
> > ---
> >  drivers/pwm/Kconfig       |  11 ++
> >  drivers/pwm/Makefile      |   1 +
> >  drivers/pwm/pwm-imx-tpm.c | 428
> > ++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 440 insertions(+)
> >  create mode 100644 drivers/pwm/pwm-imx-tpm.c
> >
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index
> > 54f8238..3ea0391 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -210,6 +210,17 @@ config PWM_IMX27
> >  	  To compile this driver as a module, choose M here: the module
> >  	  will be called pwm-imx27.
> >
> > +config PWM_IMX_TPM
> > +	tristate "i.MX TPM PWM support"
> > +	depends on ARCH_MXC || COMPILE_TEST
> > +	depends on HAVE_CLK && HAS_IOMEM
> > +	help
> > +	  Generic PWM framework driver for i.MX7ULP TPM module, TPM's
> full
> > +	  name is Low Power Timer/Pulse Width Modulation Module.
> > +
> > +	  To compile this driver as a module, choose M here: the module
> > +	  will be called pwm-imx-tpm.
> > +
> >  config PWM_JZ4740
> >  	tristate "Ingenic JZ47xx PWM support"
> >  	depends on MACH_INGENIC
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index
> > 448825e..c368599 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -19,6 +19,7 @@ obj-$(CONFIG_PWM_HIBVT)		+= pwm-
> hibvt.o
> >  obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
> >  obj-$(CONFIG_PWM_IMX1)		+= pwm-imx1.o
> >  obj-$(CONFIG_PWM_IMX27)		+= pwm-imx27.o
> > +obj-$(CONFIG_PWM_IMX_TPM)	+= pwm-imx-tpm.o
> >  obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
> >  obj-$(CONFIG_PWM_LP3943)	+= pwm-lp3943.o
> >  obj-$(CONFIG_PWM_LPC18XX_SCT)	+= pwm-lpc18xx-sct.o
> > diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
> new
> > file mode 100644 index 0000000..02403d0
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-imx-tpm.c
> > @@ -0,0 +1,428 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright 2018-2019 NXP.
> > + *
> > + * Limitations:
> > + * - The TPM counter and period counter are shared between
> > + *   multiple channels, so all channels should use same period
> > + *   settings.
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/bitops.h>
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/log2.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pwm.h>
> > +#include <linux/slab.h>
> > +
> > +#define PWM_IMX_TPM_PARAM	0x4
> > +#define PWM_IMX_TPM_GLOBAL	0x8
> > +#define PWM_IMX_TPM_SC		0x10
> > +#define PWM_IMX_TPM_CNT		0x14
> > +#define PWM_IMX_TPM_MOD		0x18
> > +#define PWM_IMX_TPM_CnSC(n)	(0x20 + (n) * 0x8)
> > +#define PWM_IMX_TPM_CnV(n)	(0x24 + (n) * 0x8)
> > +
> > +#define PWM_IMX_TPM_PARAM_CHAN			GENMASK(7,
> 0)
> > +
> > +#define PWM_IMX_TPM_SC_PS			GENMASK(2, 0)
> > +#define PWM_IMX_TPM_SC_CMOD			GENMASK(4, 3)
> > +#define PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK	BIT(3)
> 
> #define PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK
> 	FIELD_PREP(PWM_IMX_TPM_SC_CMOD, 1)
> 
> ?

Yes, it makes more sense.

> 
> > +#define PWM_IMX_TPM_SC_CPWMS			BIT(5)
> > +
> > +#define PWM_IMX_TPM_CnSC_CHF	BIT(7)
> > +#define PWM_IMX_TPM_CnSC_MSB	BIT(5)
> > +#define PWM_IMX_TPM_CnSC_MSA	BIT(4)
> > +
> > +/*
> > + * The reference manual describes this field as two separate bits.
> > +The
> > + * samantic of the two bits isn't orthogonal though, so they are
> > +treated
> > + * together as a 2-bit field here.
> > + */
> > +#define PWM_IMX_TPM_CnSC_ELS	GENMASK(3, 2)
> > +#define PWM_IMX_TPM_CnSC_ELS_POLARITY_INVERSED	0x1
> > +
> > +#define PWM_IMX_TPM_MOD_MOD	GENMASK(15, 0)
> > +
> > +struct imx_tpm_pwm_chip {
> > +	struct pwm_chip chip;
> > +	struct clk *clk;
> > +	void __iomem *base;
> > +	struct mutex lock;
> > +	u32 user_count;
> > +	u32 enable_count;
> > +	u32 real_period;
> > +};
> > +
> > +struct imx_tpm_pwm_param {
> > +	u8 prescale;
> > +	u32 mod;
> > +};
> > +
> > +static inline struct imx_tpm_pwm_chip *to_imx_tpm_pwm_chip(struct
> > +pwm_chip *chip) {
> > +	return container_of(chip, struct imx_tpm_pwm_chip, chip); }
> > +
> > +static int pwm_imx_tpm_round_state(struct pwm_chip *chip,
> > +				   struct imx_tpm_pwm_param *p,
> > +				   struct pwm_state *state,
> > +				   struct pwm_state *real_state)
> > +{
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +	u32 rate, prescale, period_count, clock_unit;
> > +	u64 tmp;
> > +
> > +	rate = clk_get_rate(tpm->clk);
> > +	tmp = (u64)state->period * rate;
> > +	clock_unit = DIV_ROUND_CLOSEST_ULL(tmp, NSEC_PER_SEC);
> > +	if (clock_unit <= PWM_IMX_TPM_MOD_MOD) {
> > +		prescale = 0;
> > +	} else {
> > +		prescale = roundup_pow_of_two(clock_unit);
> > +		prescale = ilog2(prescale) - 16;
> 
> This 16 should be a define to make it obvious where it comes from.
> 
> Maybe use:
> 
> 	#define PWM_IMX_TPM_MOD_WIDTH	16
> 	#define PWM_IMX_TPM_MOD_MOD
> 	GENMASK(PWM_IMX_TPM_MOD_WIDTH - 1, 0)
> 
> ?
> 
> If clock_unit happens to be 0x10000, we end up with prescale = 0 which is
> wrong. I think we need:
> 
> 	} else {
> 		prescale = ilog2(clock_unit) + 1 -
> PWM_IMX_TPM_MOD_WIDTH;
> 
> without the roundup.


OK.

> 
> > +	}
> > +
> > +	if ((!FIELD_FIT(PWM_IMX_TPM_SC_PS, prescale)))
> > +		return -ERANGE;
> > +	p->prescale = prescale;
> > +
> > +	period_count = (clock_unit + ((1 << prescale) >> 1)) >> prescale;
> > +	if (period_count > PWM_IMX_TPM_MOD_MOD)
> > +		return -ERANGE;
> 
> This check (together with the right way to calculate prescale) is theoretically
> superflous. period_count cannot be bigger than
> PWM_IMX_TPM_MOD_MOD. I'd either drop that check or add a scary
> warning to make people hitting this report the respective parameters.

Yeah, the check for the prescale is enough, I will drop this check.

> 
> > +	p->mod = period_count;
> > +
> > +	/* calculate real period HW can support */
> > +	tmp = (u64)period_count << prescale;
> > +	tmp *= NSEC_PER_SEC;
> > +	real_state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate);
> > +
> > +	/*
> > +	 * if eventually the PWM output is LOW, either
> > +	 * duty cycle is 0 or status is disabled, need
> > +	 * to make sure the output pin is LOW.
> 
> s/LOW/inactive/, then it's also true for inversed polarity.

OK.

> 
> > +	 */
> > +	if (!state->enabled)
> > +		real_state->duty_cycle = 0;
> > +	else
> > +		real_state->duty_cycle = state->duty_cycle;
> > +
> > +	real_state->polarity = state->polarity;
> > +	real_state->enabled = state->enabled;
> > +
> > +	return 0;
> > +}
> > +
> > +static void pwm_imx_tpm_config_counter(struct pwm_chip *chip,
> > +				       struct imx_tpm_pwm_param p)
> 
> Please pass p as a pointer. I think pwm_imx_tpm_setup_period is a better
> name here.

OK.


> 
> > +{
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +	u32 val, saved_cmod;
> > +
> > +	/* make sure counter is disabled for programming prescale */
> > +	val = readl(tpm->base + PWM_IMX_TPM_SC);
> > +	saved_cmod = FIELD_GET(PWM_IMX_TPM_SC_CMOD, val);
> > +	if (saved_cmod) {
> > +		val &= ~PWM_IMX_TPM_SC_CMOD;
> > +		writel(val, tpm->base + PWM_IMX_TPM_SC);
> 
> I thought we agreed on not stopping the counter if the PS field isn't changed?

If the PS field no need to change, the round state should already return the period
equal to current period settings, so this function will NOT be called, right?

         if (real_state.period != tpm->real_period) {
                 if (tpm->user_count > 1) {
                         ret = -EBUSY;
                         goto exit;
                 }

	pwm_imx_tpm_setup_period(chip, param);
                 tpm->real_period = real_state.period;
        } 

> 
> > +	}
> > +
> > +	/* set TPM counter prescale */
> > +	val = readl(tpm->base + PWM_IMX_TPM_SC);
> 
> val already holds this register value, no need to reread.

OK.

> 
> > +	val &= ~PWM_IMX_TPM_SC_PS;
> > +	val |= FIELD_PREP(PWM_IMX_TPM_SC_PS, p.prescale);
> > +	writel(val, tpm->base + PWM_IMX_TPM_SC);
> > +
> > +	/*
> > +	 * set period count: according to RM, the MOD register is
> > +	 * updated immediately after CMOD[1:0] = 2b'00 above
> > +	 */
> 
> So the current period isn't completed? That's wrong.

So you mean we have to wait for the current period to finish here?
I did NOT know this, so we have to compare the counter value with
the MOD value until they match then proceed the period change?

> 
> > +	writel(p.mod, tpm->base + PWM_IMX_TPM_MOD);
> > +
> > +	/* restore the clock mode if necessary */
> > +	if (saved_cmod) {
> > +		val = readl(tpm->base + PWM_IMX_TPM_SC);
> > +		val |= FIELD_PREP(PWM_IMX_TPM_SC_CMOD, saved_cmod);
> > +		writel(val, tpm->base + PWM_IMX_TPM_SC);
> > +	}
> > +}
> > +
> > +static void pwm_imx_tpm_get_state(struct pwm_chip *chip,
> > +				  struct pwm_device *pwm,
> > +				  struct pwm_state *state)
> > +{
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +	u32 rate, val;
> > +	u64 tmp;
> > +
> > +	/* get period */
> > +	state->period = tpm->real_period;
> > +
> > +	/* get duty cycle */
> > +	rate = clk_get_rate(tpm->clk);
> > +	val = readl(tpm->base + PWM_IMX_TPM_SC);
> > +	val = FIELD_GET(PWM_IMX_TPM_SC_PS, val);
> > +	tmp = readl(tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm));
> > +	tmp *= (1 << val) * NSEC_PER_SEC;
> 
> "prescale" would be a better name here than "val". As in the previous review
> round: Don't multiply by (1 << something).

OK, I missed it here. Will use below:

	prescale = FIELD_GET(PWM_IMX_TPM_SC_PS, val);
	tmp = readl(tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm));
	tmp = (tmp << prescale) * NSEC_PER_SEC;

> 
> > +	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate);
> > +
> > +	/* get polarity */
> > +	val = readl(tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm));
> > +	if (FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val) ==
> > +	    PWM_IMX_TPM_CnSC_ELS_POLARITY_INVERSED)
> > +		state->polarity = PWM_POLARITY_INVERSED;
> > +	else
> > +		/*
> > +		 * Assume reserved values (2b00 and 2b11) to yield
> > +		 * normal polarity.
> > +		 */
> > +		state->polarity = PWM_POLARITY_NORMAL;
> > +
> > +	/* get channel status */
> > +	state->enabled = FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val) ? true :
> > +false; }
> > +
> > +static void pwm_imx_tpm_apply_hw(struct pwm_chip *chip,
> > +				 struct pwm_device *pwm,
> > +				 struct pwm_state state)
> 
> Please pass a the struct pwm_state as a pointer, not as a value.

OK.

> 
> > +{
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +	struct pwm_state c;
> > +	u32 val, sc_val;
> > +	u64 tmp;
> > +
> > +	pwm_imx_tpm_get_state(chip, pwm, &c);
> > +
> > +	if (state.duty_cycle != c.duty_cycle) {
> > +		/* set duty counter */
> > +		tmp = readl(tpm->base + PWM_IMX_TPM_MOD) &
> PWM_IMX_TPM_MOD_MOD;
> > +		tmp *= state.duty_cycle;
> > +		val = DIV_ROUND_CLOSEST_ULL(tmp, state.period);
> > +		writel(val, tpm->base + PWM_IMX_TPM_CnV(pwm-
> >hwpwm));
> > +	}
> > +
> > +	if (state.enabled != c.enabled) {
> 
> This is wrong. If the PWM was running (c.enabled == true) and you are
> supposed to disable (state.enabled == false) you enable the hardware once
> more.

A little confused here, as the case you assume, inside this block, there is another
check for state.enabled, if it is false, the polarity will be set to channel disabled mode,
the polarity setting is combined together with the enable status here, am I wrong?  


> 
> > +		/*
> > +		 * set polarity (for edge-aligned PWM modes)
> > +		 *
> > +		 * ELS[1:0] = 2b10 yields normal polarity behaviour,
> > +		 * ELS[1:0] = 2b01 yields inversed polarity.
> > +		 * The other values are reserved.
> > +		 *
> > +		 * polarity settings will enabled/disable output status
> > +		 * immediately, so if the channel is disabled, need to
> > +		 * make sure MSA/MSB/ELS are set to 0 which means channel
> > +		 * disabled.
> > +		 */
> > +		val = readl(tpm->base + PWM_IMX_TPM_CnSC(pwm-
> >hwpwm));
> > +		val &= ~(PWM_IMX_TPM_CnSC_ELS |
> PWM_IMX_TPM_CnSC_MSA |
> > +			 PWM_IMX_TPM_CnSC_MSB);
> > +		sc_val = readl(tpm->base + PWM_IMX_TPM_SC);
> > +		if (state.enabled) {
> > +			val |= PWM_IMX_TPM_CnSC_MSB;
> > +			val |= (state.polarity == PWM_POLARITY_NORMAL) ?
> > +				FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 0x2) :
> > +				FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 0x1);
> 
> Introduce PWM_IMX_TPM_CnSC_ELS_POLARITY_NORMAL and use it
> together with PWM_IMX_TPM_CnSC_ELS_POLARITY_INVERSED here. If you
> put the FIELD_PREP into the definition the line doesn't get excessively long.
> 

I put the FIELD_PREP into definition, the line still long, but I agree using definition is better.

#define PWM_IMX_TPM_CnSC_ELS_INVERSED   FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 1)
#define PWM_IMX_TPM_CnSC_ELS_NORMAL     FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 2)

                         val |= (state->polarity == PWM_POLARITY_NORMAL) ?
                                 PWM_IMX_TPM_CnSC_ELS_NORMAL :
                                 PWM_IMX_TPM_CnSC_ELS_INVERSED;

> Maybe also add
> 
> 	#define PWM_IMX_TPM_CnSC_ELS_INACTIVE
> FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 0)
> 

I did NOT use the FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 0) at all, so why add it?
I don't quite understand.

> ?
> 
> > +			if (++tpm->enable_count == 1) {
> > +				/* start TPM counter */
> > +				sc_val |=
> PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK;
> > +				writel(sc_val, tpm->base +
> PWM_IMX_TPM_SC);
> > +			}
> > +		} else {
> > +			if (--tpm->enable_count == 0) {
> > +				/* stop TPM counter */
> > +				sc_val &= ~PWM_IMX_TPM_SC_CMOD;
> > +				writel(sc_val, tpm->base +
> PWM_IMX_TPM_SC);
> > +			}
> > +		}
> > +		writel(val, tpm->base + PWM_IMX_TPM_CnSC(pwm-
> >hwpwm));
> > +	}
> > +}
> > +
> > +static int pwm_imx_tpm_apply(struct pwm_chip *chip,
> > +			      struct pwm_device *pwm,
> > +			     struct pwm_state *state)
> > +{
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +	struct imx_tpm_pwm_param param;
> > +	struct pwm_state real_state;
> > +	int ret;
> > +
> > +	ret = pwm_imx_tpm_round_state(chip, &param, state, &real_state);
> > +	if (ret)
> > +		return -EINVAL;
> > +
> > +	mutex_lock(&tpm->lock);
> > +
> > +	/*
> > +	 * TPM counter is shared by multiple channels, so
> > +	 * prescale and period can NOT be modified when
> > +	 * there are multiple channels in use with different
> > +	 * period settings.
> > +	 */
> > +	if (real_state.period != tpm->real_period) {
> > +		if (tpm->user_count > 1) {
> > +			ret = -EBUSY;
> > +			goto exit;
> > +		}
> > +
> > +		pwm_imx_tpm_config_counter(chip, param);
> > +		tpm->real_period = real_state.period;
> > +	}
> 
> Maybe add a comment that this could still be optimized. For example if
> pwm_imx_tpm_round_state returned prescale = 5 but prescale is currently 6,
> you might still be able to configure

You meant for multiple users request different period case? In this block, if there is
ONLY one user and the requested period can be met by HW, it will anyway re-configure
the HW for the prescale and period I think, or I did NOT get your point?

> 
> > +
> > +	pwm_imx_tpm_apply_hw(chip, pwm, real_state);
> > +
> > +exit:
> > +	mutex_unlock(&tpm->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +static int pwm_imx_tpm_request(struct pwm_chip *chip, struct
> > +pwm_device *pwm) {
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +
> > +	mutex_lock(&tpm->lock);
> > +	tpm->user_count++;
> > +	mutex_unlock(&tpm->lock);
> > +
> > +	return 0;
> > +}
> > +
> > +static void pwm_imx_tpm_free(struct pwm_chip *chip, struct
> pwm_device
> > +*pwm) {
> > +	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
> > +
> > +	mutex_lock(&tpm->lock);
> > +	tpm->user_count--;
> > +	mutex_unlock(&tpm->lock);
> > +}
> > +
> > +static const struct pwm_ops imx_tpm_pwm_ops = {
> > +	.request = pwm_imx_tpm_request,
> > +	.free = pwm_imx_tpm_free,
> > +	.get_state = pwm_imx_tpm_get_state,
> > +	.apply = pwm_imx_tpm_apply,
> > +	.owner = THIS_MODULE,
> > +};
> > +
> > +static int pwm_imx_tpm_probe(struct platform_device *pdev) {
> > +	struct imx_tpm_pwm_chip *tpm;
> > +	int ret;
> > +	u32 val;
> > +
> > +	tpm = devm_kzalloc(&pdev->dev, sizeof(*tpm), GFP_KERNEL);
> > +	if (!tpm)
> > +		return -ENOMEM;
> > +
> > +	platform_set_drvdata(pdev, tpm);
> > +
> > +	tpm->base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(tpm->base))
> > +		return PTR_ERR(tpm->base);
> > +
> > +	tpm->clk = devm_clk_get(&pdev->dev, NULL);
> > +	if (IS_ERR(tpm->clk)) {
> > +		ret = PTR_ERR(tpm->clk);
> > +		if (ret != -EPROBE_DEFER)
> > +			dev_err(&pdev->dev,
> > +				"failed to get PWM clock: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = clk_prepare_enable(tpm->clk);
> > +	if (ret) {
> > +		dev_err(&pdev->dev,
> > +			"failed to prepare or enable clock: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	tpm->chip.dev = &pdev->dev;
> > +	tpm->chip.ops = &imx_tpm_pwm_ops;
> > +	tpm->chip.base = -1;
> > +	tpm->chip.of_xlate = of_pwm_xlate_with_flags;
> > +	tpm->chip.of_pwm_n_cells = 3;
> > +
> > +	/* get number of channels */
> > +	val = readl(tpm->base + PWM_IMX_TPM_PARAM);
> > +	tpm->chip.npwm = FIELD_GET(PWM_IMX_TPM_PARAM_CHAN, val);
> > +
> > +	mutex_init(&tpm->lock);
> > +
> > +	ret = pwmchip_add(&tpm->chip);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
> > +		clk_disable_unprepare(tpm->clk);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int pwm_imx_tpm_remove(struct platform_device *pdev) {
> > +	struct imx_tpm_pwm_chip *tpm = platform_get_drvdata(pdev);
> > +	int ret = pwmchip_remove(&tpm->chip);
> > +
> > +	clk_disable_unprepare(tpm->clk);
> > +
> > +	return ret;
> > +}
> > +
> > +static int __maybe_unused pwm_imx_tpm_suspend(struct device *dev) {
> > +	struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev);
> > +
> > +	if (tpm->enable_count > 0)
> > +		return -EBUSY;
> > +
> > +	clk_disable_unprepare(tpm->clk);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __maybe_unused pwm_imx_tpm_resume(struct device *dev) {
> > +	struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev);
> > +	int ret = 0;
> > +
> > +	if (tpm->enable_count == 0) {
> 
> tpm->enable_count cannot be different from 0 here.

OK, I will remove the check.

> 
> > +		ret = clk_prepare_enable(tpm->clk);
> > +		if (ret)
> > +			dev_err(dev,
> > +				"failed to prepare or enable clock: %d\n",
> > +				ret);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(imx_tpm_pwm_pm,
> > +			 pwm_imx_tpm_suspend, pwm_imx_tpm_resume);
> > +
> > +static const struct of_device_id imx_tpm_pwm_dt_ids[] = {
> > +	{ .compatible = "fsl,imx-tpm", },
> > +	{ /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, imx_tpm_pwm_dt_ids);
> > +
> > +static struct platform_driver imx_tpm_pwm_driver = {
> > +	.driver = {
> > +		.name = "imx-tpm-pwm",
> > +		.of_match_table = imx_tpm_pwm_dt_ids,
> > +		.pm = &imx_tpm_pwm_pm,
> > +	},
> > +	.probe	= pwm_imx_tpm_probe,
> > +	.remove = pwm_imx_tpm_remove,
> > +};
> > +module_platform_driver(imx_tpm_pwm_driver);
> > +
> > +MODULE_AUTHOR("Anson Huang <Anson.Huang@....com>");
> > +MODULE_DESCRIPTION("i.MX TPM PWM Driver"); MODULE_LICENSE("GPL
> v2");
> 
> Best regards
> Uwe
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 |
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