Re: [PATCH/RFC] ARM: mach-shmobile: sh7372 power domain prototype

["Rafael J. Wysocki" <rjw@sisk.pl>]

Hi,

To start with, I think we'll need to do that a bit differently, because
apparently some clock management code may be shared with OMAP.

Most imprtantly, the PM core is going to be changed so that power domain
callbacks will be executed instead of and not in addition to the bus type
callbacks, so platform_pm_runtime_suspend() and platform_pm_runtime_resume()
will have to be replaced by the power domain callbacks entirely.

I'm working on those changes right now, but I'd like to make the core
changes first and get everybody involved to agree with them.

Some more comments below.

On Monday, April 11, 2011, Magnus Damm wrote:
> From: Magnus Damm <damm@opensource.se>
> 
> This experimental sh7372-specific Runtime PM prototype
> adds support for the A4LC and A4MP power domains.
> 
> Tested on the Mackerel board together with the LCDC:
> 
> # blank HDMI fbdev
> echo 3 > /sys/devices/platform/sh_mobile_lcdc_fb.1/graphics/fb1/blank
> 
> # blank LCD panel fbdev
> echo 3 > /sys/devices/platform/sh_mobile_lcdc_fb.0/graphics/fb0/blank
> # unblank LCD panel fbdev
> echo 0 > /sys/devices/platform/sh_mobile_lcdc_fb.0/graphics/fb0/blank
> 
> Not-yet-signed-off-by: Magnus Damm <damm@opensource.se>
> ---
> 
>  arch/arm/mach-shmobile/pm_runtime.c |  227 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 222 insertions(+), 5 deletions(-)
> 
> --- 0001/arch/arm/mach-shmobile/pm_runtime.c
> +++ work/arch/arm/mach-shmobile/pm_runtime.c	2011-04-12 04:37:17.000000000 +0900
> @@ -3,7 +3,7 @@
>   *
>   * Runtime PM support code for SuperH Mobile ARM
>   *
> - *  Copyright (C) 2009-2010 Magnus Damm
> + *  Copyright (C) 2009-2011 Magnus Damm
>   *
>   * This file is subject to the terms and conditions of the GNU General Public
>   * License.  See the file "COPYING" in the main directory of this archive
> @@ -20,13 +20,71 @@
>  #include <linux/bitmap.h>
>  
>  #ifdef CONFIG_PM_RUNTIME
> +
> +struct pm_runtime_power_domain {
> +	spinlock_t lock;

I'm not sure if that has to be a spinlock.

> +	struct list_head idle_list;
> +	unsigned int use_cnt;
> +	unsigned int powered_off;
> +	unsigned int power_domain_bit;
> +};

My idea is that at least in some cases the power domain structure will look
the same, or very similarly, on other platforms, so perhaps it makes sense
to define it in the core rather than platform-specific.

> +
> +/* sh7372 specific stuff in common file, FIXME this should be broken out */
> +
> +static struct pm_runtime_power_domain sh7372_a4lc = {
> +	.power_domain_bit = 1,
> +};
> +
> +static struct pm_runtime_power_domain sh7372_a4mp = {
> +	.power_domain_bit = 2,
> +};
> +
> +#define SPDCR 0xe6180008
> +#define SWUCR 0xe6180014
> +#define PSTR 0xe6180080
> +
> +static void power_down(struct pm_runtime_power_domain *domain_data)
> +{
> +	unsigned int mask = 1 << domain_data->power_domain_bit;
> +
> +	if (__raw_readl(PSTR) & mask) {
> +		__raw_writel(mask, SPDCR);
> +
> +		while (__raw_readl(SPDCR) & mask)
> +			;
> +
> +		pr_info("sh7372 power domain down 0x%08x -> PSTR = 0x%08x\n",
> +		       mask, __raw_readl(PSTR));
> +	}
> +}
> +
> +static void power_up(struct pm_runtime_power_domain *domain_data)
> +{
> +	unsigned int mask = 1 << domain_data->power_domain_bit;
> +
> +	if (!(__raw_readl(PSTR) & mask)) {
> +		__raw_writel(mask, SWUCR);
> +
> +		while (__raw_readl(SWUCR) & mask)
> +			;
> +
> +		pr_info("sh7372 power domain up 0x%08x -> PSTR = 0x%08x\n",
> +			mask, __raw_readl(PSTR));
> +	}
> +}
> +
>  #define BIT_ONCE 0
>  #define BIT_ACTIVE 1
>  #define BIT_CLK_ENABLED 2
> +#define BIT_SUSPENDED 3
>  
>  struct pm_runtime_data {
>  	unsigned long flags;
>  	struct clk *clk;
> +
> +	struct device *dev;
> +	struct list_head entry; /* for pm_runtime_power_domain idle_list */
> +	struct pm_runtime_power_domain *domain_data;
>  };
>  
>  static void __devres_release(struct device *dev, void *res)
> @@ -47,6 +105,159 @@ static struct pm_runtime_data *__to_prd(
>  	return devres_find(dev, __devres_release, NULL, NULL);
>  }
>  
> +static int __power_domain_runtime_suspend(struct device *d)
> +{
> +	struct pm_runtime_data *prd = __to_prd(d);
> +	int ret = 0;
> +
> +	dev_dbg(d, "__power_domain_runtime_suspend()\n");
> +
> +	BUG_ON(!prd);
> +
> +	if (!test_bit(BIT_SUSPENDED, &prd->flags)) {

Those things need not be handled with the help of test_bit() and friends I think.

The PM core guarantees that runtime PM callbacks will never be executed
concurrently with one another for the same device, so all things that are
only accessed by those callbacks may be simple bit fields.

> +		if (d->driver && d->driver->pm &&
> +		    d->driver->pm->runtime_suspend) {
> +			if (!test_bit(BIT_CLK_ENABLED, &prd->flags))
> +				clk_enable(prd->clk);
> +			ret = d->driver->pm->runtime_suspend(d);
> +			clk_disable(prd->clk);
> +			clear_bit(BIT_CLK_ENABLED, &prd->flags);
> +
> +			if (ret = 0)
> +				set_bit(BIT_SUSPENDED, &prd->flags);
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static int power_domain_runtime_suspend(struct device *dev)
> +{
> +	struct pm_runtime_data *prd = __to_prd(dev);
> +	struct pm_runtime_power_domain *domain_data = prd->domain_data;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	dev_dbg(dev, "power_domain_runtime_suspend() %d\n",
> +		domain_data->use_cnt);
> +
> +	spin_lock_irqsave(&domain_data->lock, flags);
> +
> +	list_add_tail(&prd->entry, &domain_data->idle_list);
> +	domain_data->use_cnt--;
> +
> +	if (domain_data->use_cnt = 0) {
> +		struct pm_runtime_data *p;
> +
> +		list_for_each_entry(p, &domain_data->idle_list, entry) {
> +			ret = __power_domain_runtime_suspend(p->dev);
> +			if (ret)
> +				break;
> +		}
> +
> +		if (ret = 0)
> +			power_down(domain_data);
> +	}
> +
> +	spin_unlock_irqrestore(&domain_data->lock, flags);
> +
> +	return ret;
> +}
> +
> +static int __power_domain_runtime_resume(struct device *d)
> +{
> +	struct pm_runtime_data *prd = __to_prd(d);
> +	int ret = 0;
> +
> +	dev_dbg(d, "__power_domain_runtime_resume()\n");
> +
> +	BUG_ON(!prd);
> +
> +	if (test_bit(BIT_SUSPENDED, &prd->flags)) {
> +		if (!test_bit(BIT_CLK_ENABLED, &prd->flags)) {
> +			clk_enable(prd->clk);
> +			set_bit(BIT_CLK_ENABLED, &prd->flags);
> +		}
> +
> +		if (d->driver && d->driver->pm &&
> +		    d->driver->pm->runtime_resume)
> +			ret = d->driver->pm->runtime_resume(d);
> +
> +		if (ret = 0)
> +			clear_bit(BIT_SUSPENDED, &prd->flags);
> +		else {
> +			clk_disable(prd->clk);
> +			clear_bit(BIT_CLK_ENABLED, &prd->flags);
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static int power_domain_runtime_resume(struct device *dev)
> +{
> +	struct pm_runtime_data *prd = __to_prd(dev);
> +	struct pm_runtime_power_domain *domain_data = prd->domain_data;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	dev_dbg(dev, "power_domain_runtime_resume() %d\n",
> +		domain_data->use_cnt);
> +
> +	spin_lock_irqsave(&domain_data->lock, flags);
> +
> +	if (domain_data->use_cnt = 0)
> +		power_up(domain_data);
> +
> +	ret = __power_domain_runtime_resume(dev);
> +
> +	if (ret = 0) {
> +		domain_data->use_cnt++;
> +		list_del(&prd->entry);
> +	} else {
> +		if (domain_data->use_cnt = 0)
> +			power_down(domain_data);
> +	}
> +
> +	spin_unlock_irqrestore(&domain_data->lock, flags);
> +
> +	return ret;
> +}

The majority of the code above doesn't look like shmobile-specific or even
ARM-specific, so I think it will make sense to put it into drivers/base/power.
Of course, power_up() and power_down() are mackerel-specific, but they may
be provided as function pointers in the power domain structure.

> +
> +static struct dev_power_domain power_domain = {
> +	.ops.runtime_suspend = power_domain_runtime_suspend,
> +	.ops.runtime_resume = power_domain_runtime_resume,
> +};
> +
> +static void power_domain_init(struct device *dev, struct pm_runtime_data *prd)
> +{
> +	struct pm_runtime_power_domain *domain_data = NULL;
> +
> +	if (strcmp(dev_name(dev), "sh_mobile_lcdc_fb.0") = 0)
> +		domain_data = &sh7372_a4lc;
> +
> +	if (strcmp(dev_name(dev), "sh_mobile_lcdc_fb.1") = 0)
> +		domain_data = &sh7372_a4lc;
> +
> +	if (strcmp(dev_name(dev), "sh_fsi2") = 0)
> +		domain_data = &sh7372_a4mp;

The above things don't look quite right.  I think the connections between
device objects and power domain objects should be set up in the board file.

> +
> +	if (domain_data) {
> +		dev->pwr_domain = &power_domain;
> +		prd->dev = dev;
> +		INIT_LIST_HEAD(&prd->entry);
> +		prd->domain_data = domain_data;
> +		domain_data->use_cnt++;
> +		if (domain_data->use_cnt = 1) {

This doesn't look nice to me.

> +			INIT_LIST_HEAD(&domain_data->idle_list);
> +			spin_lock_init(&domain_data->lock);
> +		}
> +
> +		dev_dbg(dev, "domain data available use cnt = %d\n",
> +			domain_data->use_cnt);
> +	}
> +}
> +
>  static void platform_pm_runtime_init(struct device *dev,
>  				     struct pm_runtime_data *prd)
>  {
> @@ -55,6 +266,7 @@ static void platform_pm_runtime_init(str
>  		if (!IS_ERR(prd->clk)) {
>  			set_bit(BIT_ACTIVE, &prd->flags);
>  			dev_info(dev, "clocks managed by runtime pm\n");
> +			power_domain_init(dev, prd);
>  		}
>  	}
>  }
> @@ -75,8 +287,11 @@ int platform_pm_runtime_suspend(struct d
>  	platform_pm_runtime_bug(dev, prd);
>  
>  	if (prd && test_bit(BIT_ACTIVE, &prd->flags)) {
> -		clk_disable(prd->clk);
> -		clear_bit(BIT_CLK_ENABLED, &prd->flags);
> +		if (test_bit(BIT_CLK_ENABLED, &prd->flags)) {
> +			clk_disable(prd->clk);
> +			clear_bit(BIT_CLK_ENABLED, &prd->flags);
> +		}
> +
>  	}
>  
>  	return 0;
> @@ -91,8 +306,10 @@ int platform_pm_runtime_resume(struct de
>  	platform_pm_runtime_init(dev, prd);
>  
>  	if (prd && test_bit(BIT_ACTIVE, &prd->flags)) {
> -		clk_enable(prd->clk);
> -		set_bit(BIT_CLK_ENABLED, &prd->flags);
> +		if (!test_bit(BIT_CLK_ENABLED, &prd->flags)) {
> +			clk_enable(prd->clk);
> +			set_bit(BIT_CLK_ENABLED, &prd->flags);
> +		}
>  	}
>  
>  	return 0;

Thanks,
Rafael