Re: [PATCH v3 1/5] pwms: pwm-ti*: Remove support for local clock gating

[Sekhar Nori <nsekhar@ti.com>]

+ Thierry, PWM subsystem maintainer.

On Friday 26 February 2016 04:06 AM, Franklin S Cooper Jr wrote:
> The PWMSS local clock gating registers have no real purpose on OMAP ARM
> devices. These registers were left over registers from DSP IP where the
> PRCM doesn't exist. There is a silicon bug where gating and ungating clocks
> don't function properly. TRMs will be update to indicate that these
> registers shouldn't be touched.
> 
> Therefore, all code that accesses the PWMSS_CLKCONFIG or PWMSS_CLKSTATUS
> will be removed by this patch with zero loss of functionality by the ECAP
> and EPWM drivers.
> 
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> ---
> Version 3 changes:
> New patch
> 
>  drivers/pwm/pwm-tiecap.c   | 28 --------------------------
>  drivers/pwm/pwm-tiehrpwm.c | 29 ---------------------------
>  drivers/pwm/pwm-tipwmss.c  | 49 ----------------------------------------------
>  drivers/pwm/pwm-tipwmss.h  | 39 ------------------------------------
>  4 files changed, 145 deletions(-)
>  delete mode 100644 drivers/pwm/pwm-tipwmss.h
> 
> diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c
> index 616af76..9e0865d7 100644
> --- a/drivers/pwm/pwm-tiecap.c
> +++ b/drivers/pwm/pwm-tiecap.c
> @@ -27,8 +27,6 @@
>  #include <linux/pwm.h>
>  #include <linux/of_device.h>
>  
> -#include "pwm-tipwmss.h"
> -
>  /* ECAP registers and bits definitions */
>  #define CAP1			0x08
>  #define CAP2			0x0C
> @@ -206,7 +204,6 @@ static int ecap_pwm_probe(struct platform_device *pdev)
>  	struct resource *r;
>  	struct clk *clk;
>  	struct ecap_pwm_chip *pc;
> -	u16 status;
>  
>  	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
>  	if (!pc)
> @@ -243,40 +240,15 @@ static int ecap_pwm_probe(struct platform_device *pdev)
>  	}
>  
>  	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_get_sync(&pdev->dev);
> -
> -	status = pwmss_submodule_state_change(pdev->dev.parent,
> -			PWMSS_ECAPCLK_EN);
> -	if (!(status & PWMSS_ECAPCLK_EN_ACK)) {
> -		dev_err(&pdev->dev, "PWMSS config space clock enable failed\n");
> -		ret = -EINVAL;
> -		goto pwmss_clk_failure;
> -	}
> -
> -	pm_runtime_put_sync(&pdev->dev);
>  
>  	platform_set_drvdata(pdev, pc);
>  	return 0;
> -
> -pwmss_clk_failure:
> -	pm_runtime_put_sync(&pdev->dev);
> -	pm_runtime_disable(&pdev->dev);
> -	pwmchip_remove(&pc->chip);
> -	return ret;
>  }
>  
>  static int ecap_pwm_remove(struct platform_device *pdev)
>  {
>  	struct ecap_pwm_chip *pc = platform_get_drvdata(pdev);
>  
> -	pm_runtime_get_sync(&pdev->dev);
> -	/*
> -	 * Due to hardware misbehaviour, acknowledge of the stop_req
> -	 * is missing. Hence checking of the status bit skipped.
> -	 */
> -	pwmss_submodule_state_change(pdev->dev.parent, PWMSS_ECAPCLK_STOP_REQ);
> -	pm_runtime_put_sync(&pdev->dev);
> -
>  	pm_runtime_disable(&pdev->dev);
>  	return pwmchip_remove(&pc->chip);
>  }
> diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c
> index 6a41e66..e09b1f0 100644
> --- a/drivers/pwm/pwm-tiehrpwm.c
> +++ b/drivers/pwm/pwm-tiehrpwm.c
> @@ -27,8 +27,6 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/of_device.h>
>  
> -#include "pwm-tipwmss.h"
> -
>  /* EHRPWM registers and bits definitions */
>  
>  /* Time base module registers */
> @@ -437,7 +435,6 @@ static int ehrpwm_pwm_probe(struct platform_device *pdev)
>  	struct resource *r;
>  	struct clk *clk;
>  	struct ehrpwm_pwm_chip *pc;
> -	u16 status;
>  
>  	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
>  	if (!pc)
> @@ -487,27 +484,9 @@ static int ehrpwm_pwm_probe(struct platform_device *pdev)
>  	}
>  
>  	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_get_sync(&pdev->dev);
> -
> -	status = pwmss_submodule_state_change(pdev->dev.parent,
> -			PWMSS_EPWMCLK_EN);
> -	if (!(status & PWMSS_EPWMCLK_EN_ACK)) {
> -		dev_err(&pdev->dev, "PWMSS config space clock enable failed\n");
> -		ret = -EINVAL;
> -		goto pwmss_clk_failure;
> -	}
> -
> -	pm_runtime_put_sync(&pdev->dev);
>  
>  	platform_set_drvdata(pdev, pc);
>  	return 0;
> -
> -pwmss_clk_failure:
> -	pm_runtime_put_sync(&pdev->dev);
> -	pm_runtime_disable(&pdev->dev);
> -	pwmchip_remove(&pc->chip);
> -	clk_unprepare(pc->tbclk);
> -	return ret;
>  }
>  
>  static int ehrpwm_pwm_remove(struct platform_device *pdev)
> @@ -516,14 +495,6 @@ static int ehrpwm_pwm_remove(struct platform_device *pdev)
>  
>  	clk_unprepare(pc->tbclk);
>  
> -	pm_runtime_get_sync(&pdev->dev);
> -	/*
> -	 * Due to hardware misbehaviour, acknowledge of the stop_req
> -	 * is missing. Hence checking of the status bit skipped.
> -	 */
> -	pwmss_submodule_state_change(pdev->dev.parent, PWMSS_EPWMCLK_STOP_REQ);
> -	pm_runtime_put_sync(&pdev->dev);
> -
>  	pm_runtime_put_sync(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  	return pwmchip_remove(&pc->chip);
> diff --git a/drivers/pwm/pwm-tipwmss.c b/drivers/pwm/pwm-tipwmss.c
> index 5cf65a1..829f499 100644
> --- a/drivers/pwm/pwm-tipwmss.c
> +++ b/drivers/pwm/pwm-tipwmss.c
> @@ -22,32 +22,6 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/of_device.h>
>  
> -#include "pwm-tipwmss.h"
> -
> -#define PWMSS_CLKCONFIG		0x8	/* Clock gating reg */
> -#define PWMSS_CLKSTATUS		0xc	/* Clock gating status reg */
> -
> -struct pwmss_info {
> -	void __iomem	*mmio_base;
> -	struct mutex	pwmss_lock;
> -	u16		pwmss_clkconfig;
> -};
> -
> -u16 pwmss_submodule_state_change(struct device *dev, int set)
> -{
> -	struct pwmss_info *info = dev_get_drvdata(dev);
> -	u16 val;
> -
> -	mutex_lock(&info->pwmss_lock);
> -	val = readw(info->mmio_base + PWMSS_CLKCONFIG);
> -	val |= set;
> -	writew(val , info->mmio_base + PWMSS_CLKCONFIG);
> -	mutex_unlock(&info->pwmss_lock);
> -
> -	return readw(info->mmio_base + PWMSS_CLKSTATUS);
> -}
> -EXPORT_SYMBOL(pwmss_submodule_state_change);
> -
>  static const struct of_device_id pwmss_of_match[] = {
>  	{ .compatible	= "ti,am33xx-pwmss" },
>  	{},
> @@ -57,24 +31,10 @@ MODULE_DEVICE_TABLE(of, pwmss_of_match);
>  static int pwmss_probe(struct platform_device *pdev)
>  {
>  	int ret;
> -	struct resource *r;
> -	struct pwmss_info *info;
>  	struct device_node *node = pdev->dev.of_node;
>  
> -	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
> -	if (!info)
> -		return -ENOMEM;
> -
> -	mutex_init(&info->pwmss_lock);
> -
> -	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	info->mmio_base = devm_ioremap_resource(&pdev->dev, r);
> -	if (IS_ERR(info->mmio_base))
> -		return PTR_ERR(info->mmio_base);
> -
>  	pm_runtime_enable(&pdev->dev);
>  	pm_runtime_get_sync(&pdev->dev);
> -	platform_set_drvdata(pdev, info);
>  
>  	/* Populate all the child nodes here... */
>  	ret = of_platform_populate(node, NULL, NULL, &pdev->dev);
> @@ -86,30 +46,21 @@ static int pwmss_probe(struct platform_device *pdev)
>  
>  static int pwmss_remove(struct platform_device *pdev)
>  {
> -	struct pwmss_info *info = platform_get_drvdata(pdev);
> -
>  	pm_runtime_put_sync(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
> -	mutex_destroy(&info->pwmss_lock);
>  	return 0;
>  }
>  
>  #ifdef CONFIG_PM_SLEEP
>  static int pwmss_suspend(struct device *dev)
>  {
> -	struct pwmss_info *info = dev_get_drvdata(dev);
> -
> -	info->pwmss_clkconfig = readw(info->mmio_base + PWMSS_CLKCONFIG);
>  	pm_runtime_put_sync(dev);
>  	return 0;
>  }
>  
>  static int pwmss_resume(struct device *dev)
>  {
> -	struct pwmss_info *info = dev_get_drvdata(dev);
> -
>  	pm_runtime_get_sync(dev);
> -	writew(info->pwmss_clkconfig, info->mmio_base + PWMSS_CLKCONFIG);
>  	return 0;
>  }
>  #endif
> diff --git a/drivers/pwm/pwm-tipwmss.h b/drivers/pwm/pwm-tipwmss.h
> deleted file mode 100644
> index 10ad804..0000000
> --- a/drivers/pwm/pwm-tipwmss.h
> +++ /dev/null
> @@ -1,39 +0,0 @@
> -/*
> - * TI PWM Subsystem driver
> - *
> - * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License as published by
> - * the Free Software Foundation; either version 2 of the License, or
> - * (at your option) any later version.
> - *
> - * This program is distributed in the hope that it will be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> - * GNU General Public License for more details.
> - *
> - */
> -
> -#ifndef __TIPWMSS_H
> -#define __TIPWMSS_H
> -
> -/* PWM substem clock gating */
> -#define PWMSS_ECAPCLK_EN	BIT(0)
> -#define PWMSS_ECAPCLK_STOP_REQ	BIT(1)
> -#define PWMSS_EPWMCLK_EN	BIT(8)
> -#define PWMSS_EPWMCLK_STOP_REQ	BIT(9)
> -
> -#define PWMSS_ECAPCLK_EN_ACK	BIT(0)
> -#define PWMSS_EPWMCLK_EN_ACK	BIT(8)
> -
> -#ifdef CONFIG_PWM_TIPWMSS
> -extern u16 pwmss_submodule_state_change(struct device *dev, int set);
> -#else
> -static inline u16 pwmss_submodule_state_change(struct device *dev, int set)
> -{
> -	/* return success status value */
> -	return 0xFFFF;
> -}
> -#endif
> -#endif	/* __TIPWMSS_H */
>