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Date: Fri, 26 Feb 2016 15:57:28 +0530
From: Sekhar Nori <nsekhar@...com>
To: Franklin S Cooper Jr <fcooper@...com>, <paul@...an.com>,
<t-kristo@...com>, <tony@...mide.com>, <vigneshr@...com>,
<linux-pwm@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-clk@...r.kernel.org>,
Thierry Reding <thierry.reding@...il.com>
Subject: Re: [PATCH v3 1/5] pwms: pwm-ti*: Remove support for local clock
gating
+ 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@...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 */
>
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