linux-kernel - Re: [PATCH 1/7] pwm: jz4740: Obtain regmap from parent node

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Message-ID: <20190812061802.oj45hhlooizge7dy@pengutronix.de>
Date:   Mon, 12 Aug 2019 08:18:02 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Thierry Reding <thierry.reding@...il.com>, od@...c.me,
        linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mathieu Malaterre <malat@...ian.org>,
        Artur Rojek <contact@...ur-rojek.eu>
Subject: Re: [PATCH 1/7] pwm: jz4740: Obtain regmap from parent node

Hello Paul,

On Fri, Aug 09, 2019 at 07:04:56PM +0200, Paul Cercueil wrote:
> Le ven. 9 août 2019 à 18:51, Uwe =?iso-8859-1?q?Kleine-K=F6nig?=
> <u.kleine-koenig@...gutronix.de> a écrit :
> > On Fri, Aug 09, 2019 at 02:30:25PM +0200, Paul Cercueil wrote:
> > >  The TCU registers are shared between a handful of drivers, accessing
> > >  them through the same regmap.
> > > 
> > >  While this driver is devicetree-compatible, it is never (as of now)
> > >  probed from devicetree, so this change does not introduce a ABI
> > > problem
> > >  with current devicetree files.
> > 
> > If you adapt the binding also update the binding doc please.
> 
> It's already updated, in mips-next, so it'll be in the next -rc1.

This is a useful information for the commit log.

> > >  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> > >  Tested-by: Mathieu Malaterre <malat@...ian.org>
> > >  Tested-by: Artur Rojek <contact@...ur-rojek.eu>
> > 
> > nitpick: put your S-o-b line after the other tags you added.
> > 
> > >  ---
> > >   drivers/pwm/Kconfig      |  1 +
> > >   drivers/pwm/pwm-jz4740.c | 80 ++++++++++++++++++++++++++--------------
> > >   2 files changed, 53 insertions(+), 28 deletions(-)
> > > 
> > >  diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > >  index a7e57516959e..cc4df0ec978a 100644
> > >  --- a/drivers/pwm/Kconfig
> > >  +++ b/drivers/pwm/Kconfig
> > >  @@ -225,6 +225,7 @@ config PWM_IMX_TPM
> > >   config PWM_JZ4740
> > >   	tristate "Ingenic JZ47xx PWM support"
> > >   	depends on MACH_INGENIC
> > >  +	select MFD_SYSCON
> > >   	help
> > >   	  Generic PWM framework driver for Ingenic JZ47xx based
> > >   	  machines.
> > >  diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
> > >  index f901e8a0d33d..7aea5e0c6e18 100644
> > >  --- a/drivers/pwm/pwm-jz4740.c
> > >  +++ b/drivers/pwm/pwm-jz4740.c
> > >  @@ -8,18 +8,20 @@
> > >   #include <linux/err.h>
> > >   #include <linux/gpio.h>
> > >   #include <linux/kernel.h>
> > >  +#include <linux/mfd/ingenic-tcu.h>
> > >  +#include <linux/mfd/syscon.h>
> > >   #include <linux/module.h>
> > >   #include <linux/of_device.h>
> > >   #include <linux/platform_device.h>
> > >   #include <linux/pwm.h>
> > >  -
> > >  -#include <asm/mach-jz4740/timer.h>
> > >  +#include <linux/regmap.h>
> > > 
> > >   #define NUM_PWM 8
> > > 
> > >   struct jz4740_pwm_chip {
> > >   	struct pwm_chip chip;
> > >   	struct clk *clk;
> > >  +	struct regmap *map;
> > >   };
> > > 
> > >   static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
> > >  @@ -29,6 +31,8 @@ static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
> > > 
> > >   static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> > >   {
> > >  +	struct jz4740_pwm_chip *jz = to_jz4740(chip);
> > >  +
> > >   	/*
> > >   	 * Timers 0 and 1 are used for system tasks, so they are unavailable
> > >   	 * for use as PWMs.
> > >  @@ -36,50 +40,53 @@ static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> > >   	if (pwm->hwpwm < 2)
> > >   		return -EBUSY;
> > > 
> > >  -	jz4740_timer_start(pwm->hwpwm);
> > >  +	regmap_write(jz->map, TCU_REG_TSCR, BIT(pwm->hwpwm));
> > 
> > jz4740_timer_start does
> > 
> > 	writel(BIT(timer), jz4740_timer_base + JZ_REG_TIMER_STOP_CLEAR);
> > 
> > with
> > 
> > #define JZ_REG_TIMER_STOP_CLEAR         0x2C
> > 
> > and
> > 
> > #define TCU_REG_TSCR            0x3c
> > 
> > I wonder why the offsets are different.
> 
> The offset are different because the base is different.

This is a useful information for the commit log.
 
> > > 
> > >   	return 0;
> > >   }
> > > 
> > >   static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> > >   {
> > >  -	jz4740_timer_set_ctrl(pwm->hwpwm, 0);
> > >  +	struct jz4740_pwm_chip *jz = to_jz4740(chip);
> > > 
> > >  -	jz4740_timer_stop(pwm->hwpwm);
> > >  +	regmap_write(jz->map, TCU_REG_TSCR, BIT(pwm->hwpwm));
> > 
> > jz4740_timer_set_ctrl writes to offset (((pwm->hwpwm) * 0x10) + 0x3C)
> > and jz4740_timer_stop to offset 0x1c. The regmap_write doesn't do both
> > of them but instead writes to offset 0x3c.
> 
> I guess it should have been TCU_REG_TSSR ("Timer Stop Set Register") and
> I didn't notice because the next patch drops this write anyway.
> 
> I'll do as you suggested in your other reply and swap the two patches if
> it makes things easier, it'll get rid of this write.

ok.

Best regards
Uwe

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Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |