linux-kernel - Re: [RFC v4 07/10] pwm: dwc: make timer clock configurable

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Message-ID: <20220914161749.uqdjtsr57dydu4jm@pengutronix.de>
Date:   Wed, 14 Sep 2022 18:17:49 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Ben Dooks <ben.dooks@...ive.com>
Cc:     linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Greentime Hu <greentime.hu@...ive.com>,
        jarkko.nikula@...ux.intel.com,
        William Salmon <william.salmon@...ive.com>,
        Jude Onyenegecha <jude.onyenegecha@...ive.com>
Subject: Re: [RFC v4 07/10] pwm: dwc: make timer clock configurable

Hello Ben,

On Tue, Aug 16, 2022 at 10:14:51PM +0100, Ben Dooks wrote:
> Add a configurable clock base rate for the pwm as when being built
> for non-PCI the block may be sourced from an internal clock.
> 
> Signed-off-by: Ben Dooks <ben.dooks@...ive.com>
> ---
> v4:
>  - moved earlier before the of changes to make the of changes one patch
> v2:
>   - removed the ifdef and merged the other clock patch in here
> ---
>  drivers/pwm/pwm-dwc-pci.c |  1 +
>  drivers/pwm/pwm-dwc.c     | 10 ++++++----
>  drivers/pwm/pwm-dwc.h     |  2 ++
>  3 files changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-dwc-pci.c b/drivers/pwm/pwm-dwc-pci.c
> index 2213d0e7f3c8..949423e368f9 100644
> --- a/drivers/pwm/pwm-dwc-pci.c
> +++ b/drivers/pwm/pwm-dwc-pci.c
> @@ -20,6 +20,7 @@
>  #include <linux/pci.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pwm.h>
> +#include <linux/clk.h>
>  
>  #include "pwm-dwc.h"
>  

This hunk is strange. Why do you add a header but no user of a symbol
declared in that header? Maybe it should go to pwm-dwc.h?

> diff --git a/drivers/pwm/pwm-dwc.c b/drivers/pwm/pwm-dwc.c
> index 90a8ae1252a1..1251620ab771 100644
> --- a/drivers/pwm/pwm-dwc.c
> +++ b/drivers/pwm/pwm-dwc.c
> @@ -14,6 +14,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
> +#include <linux/clk.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pwm.h>
>  
> @@ -47,13 +48,13 @@ static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
>  	 * periods and check are the result within HW limits between 1 and
>  	 * 2^32 periods.
>  	 */
> -	tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, DWC_CLK_PERIOD_NS);
> +	tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, dwc->clk_ns);
>  	if (tmp < 1 || tmp > (1ULL << 32))
>  		return -ERANGE;
>  	low = tmp - 1;
>  
>  	tmp = DIV_ROUND_CLOSEST_ULL(state->period - state->duty_cycle,
> -				    DWC_CLK_PERIOD_NS);
> +				    dwc->clk_ns);
>  	if (tmp < 1 || tmp > (1ULL << 32))
>  		return -ERANGE;
>  	high = tmp - 1;
> @@ -128,12 +129,12 @@ static void dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  
>  	duty = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
>  	duty += 1;
> -	duty *= DWC_CLK_PERIOD_NS;
> +	duty *= dwc->clk_ns;
>  	state->duty_cycle = duty;
>  
>  	period = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm));
>  	period += 1;
> -	period *= DWC_CLK_PERIOD_NS;
> +	period *= dwc->clk_ns;
>  	period += duty;
>  	state->period = period;
>  
> @@ -156,6 +157,7 @@ struct dwc_pwm *dwc_pwm_alloc(struct device *dev)
>  	if (!dwc)
>  		return NULL;
>  
> +	dwc->clk_ns = 10;
>  	dwc->chip.dev = dev;
>  	dwc->chip.ops = &dwc_pwm_ops;
>  	dwc->chip.npwm = DWC_TIMERS_TOTAL;

After this conversion all usage of DWC_CLK_PERIOD_NS is done so the
#define can go away?

> diff --git a/drivers/pwm/pwm-dwc.h b/drivers/pwm/pwm-dwc.h
> index 68f98eb76152..e5a1f7be7bc8 100644
> --- a/drivers/pwm/pwm-dwc.h
> +++ b/drivers/pwm/pwm-dwc.h
> @@ -41,6 +41,8 @@ struct dwc_pwm_ctx {
>  struct dwc_pwm {
>  	struct pwm_chip chip;
>  	void __iomem *base;
> +	struct clk *clk;
> +	unsigned int clk_ns;
>  	struct dwc_pwm_ctx ctx[DWC_TIMERS_TOTAL];
>  };
>  #define to_dwc_pwm(p)	(container_of((p), struct dwc_pwm, chip))
> -- 
> 2.35.1
> 
> 

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

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