Re: [PATCH 1/2] PM: add runtime PM support to core Primecell driver

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On Tuesday, August 23, 2011, Russell King - ARM Linux wrote:
> Add runtime PM support to the core Primecell driver, following the PCI
> model of how this is done.
> 
> Rather than having every driver fiddle about with enabling runtime PM,
> that's dealt with in the core and instead, drivers just do a put() in
> their probe and a balancing get() in their remove function to activate
> runtime PM for the device.
> 
> As we're dealing with enabling runtime PM in the core, fix up spi-pl022
> as it must not enable and disable runtime PM itself anymore.
> 
> Tested-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>

Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>

> ---
>  drivers/amba/bus.c      |   57 +++++++++++++++++++++++++++++++--
>  drivers/spi/spi-pl022.c |   80 ++++++++++++++++++++++++++++-------------------
>  2 files changed, 102 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index d74926e..84bdaac 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -365,6 +365,40 @@ static int amba_pm_restore_noirq(struct device *dev)
>  
>  #endif /* !CONFIG_HIBERNATE_CALLBACKS */
>  
> +#ifdef CONFIG_PM_RUNTIME
> +/*
> + * Hooks to provide runtime PM of the pclk (bus clock).  It is safe to
> + * enable/disable the bus clock at runtime PM suspend/resume as this
> + * does not result in loss of context.  However, disabling vcore power
> + * would do, so we leave that to the driver.
> + */
> +static int amba_pm_runtime_suspend(struct device *dev)
> +{
> +	struct amba_device *pcdev = to_amba_device(dev);
> +	int ret = pm_generic_runtime_suspend(dev);
> +
> +	if (ret == 0 && dev->driver)
> +		clk_disable(pcdev->pclk);
> +
> +	return ret;
> +}
> +
> +static int amba_pm_runtime_resume(struct device *dev)
> +{
> +	struct amba_device *pcdev = to_amba_device(dev);
> +	int ret;
> +
> +	if (dev->driver) {
> +		ret = clk_enable(pcdev->pclk);
> +		/* Failure is probably fatal to the system, but... */
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return pm_generic_runtime_resume(dev);
> +}
> +#endif
> +
>  #ifdef CONFIG_PM
>  
>  static const struct dev_pm_ops amba_pm = {
> @@ -383,8 +417,8 @@ static const struct dev_pm_ops amba_pm = {
>  	.poweroff_noirq	= amba_pm_poweroff_noirq,
>  	.restore_noirq	= amba_pm_restore_noirq,
>  	SET_RUNTIME_PM_OPS(
> -		pm_generic_runtime_suspend,
> -		pm_generic_runtime_resume,
> +		amba_pm_runtime_suspend,
> +		amba_pm_runtime_resume,
>  		pm_generic_runtime_idle
>  	)
>  };
> @@ -494,10 +528,18 @@ static int amba_probe(struct device *dev)
>  		if (ret)
>  			break;
>  
> +		pm_runtime_get_noresume(dev);
> +		pm_runtime_set_active(dev);
> +		pm_runtime_enable(dev);
> +
>  		ret = pcdrv->probe(pcdev, id);
>  		if (ret == 0)
>  			break;
>  
> +		pm_runtime_disable(dev);
> +		pm_runtime_set_suspended(dev);
> +		pm_runtime_put_noidle(dev);
> +
>  		amba_put_disable_pclk(pcdev);
>  		amba_put_disable_vcore(pcdev);
>  	} while (0);
> @@ -509,7 +551,16 @@ static int amba_remove(struct device *dev)
>  {
>  	struct amba_device *pcdev = to_amba_device(dev);
>  	struct amba_driver *drv = to_amba_driver(dev->driver);
> -	int ret = drv->remove(pcdev);
> +	int ret;
> +
> +	pm_runtime_get_sync(dev);
> +	ret = drv->remove(pcdev);
> +	pm_runtime_put_noidle(dev);
> +
> +	/* Undo the runtime PM settings in amba_probe() */
> +	pm_runtime_disable(dev);
> +	pm_runtime_set_suspended(dev);
> +	pm_runtime_put_noidle(dev);
>  
>  	amba_put_disable_pclk(pcdev);
>  	amba_put_disable_vcore(pcdev);
> diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
> index 730b4a3..078338f 100644
> --- a/drivers/spi/spi-pl022.c
> +++ b/drivers/spi/spi-pl022.c
> @@ -515,9 +515,6 @@ static void giveback(struct pl022 *pl022)
>  	if (msg->complete)
>  		msg->complete(msg->context);
>  	/* This message is completed, so let's turn off the clocks & power */
> -	clk_disable(pl022->clk);
> -	amba_pclk_disable(pl022->adev);
> -	amba_vcore_disable(pl022->adev);
>  	pm_runtime_put(&pl022->adev->dev);
>  }
>  
> @@ -1545,9 +1542,6 @@ static void pump_messages(struct work_struct *work)
>  	 * (poll/interrupt/DMA)
>  	 */
>  	pm_runtime_get_sync(&pl022->adev->dev);
> -	amba_vcore_enable(pl022->adev);
> -	amba_pclk_enable(pl022->adev);
> -	clk_enable(pl022->clk);
>  	restore_state(pl022);
>  	flush(pl022);
>  
> @@ -2186,8 +2180,6 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
>  	}
>  	printk(KERN_INFO "pl022: mapped registers from 0x%08x to %p\n",
>  	       adev->res.start, pl022->virtbase);
> -	pm_runtime_enable(dev);
> -	pm_runtime_resume(dev);
>  
>  	pl022->clk = clk_get(&adev->dev, NULL);
>  	if (IS_ERR(pl022->clk)) {
> @@ -2195,7 +2187,6 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
>  		dev_err(&adev->dev, "could not retrieve SSP/SPI bus clock\n");
>  		goto err_no_clk;
>  	}
> -
>  	/* Disable SSP */
>  	writew((readw(SSP_CR1(pl022->virtbase)) & (~SSP_CR1_MASK_SSE)),
>  	       SSP_CR1(pl022->virtbase));
> @@ -2235,12 +2226,9 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
>  		goto err_spi_register;
>  	}
>  	dev_dbg(dev, "probe succeeded\n");
> -	/*
> -	 * Disable the silicon block pclk and any voltage domain and just
> -	 * power it up and clock it when it's needed
> -	 */
> -	amba_pclk_disable(adev);
> -	amba_vcore_disable(adev);
> +
> +	/* let runtime pm put suspend */
> +	pm_runtime_put(dev);
>  	return 0;
>  
>   err_spi_register:
> @@ -2249,7 +2237,6 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id)
>  	destroy_queue(pl022);
>  	pl022_dma_remove(pl022);
>  	free_irq(adev->irq[0], pl022);
> -	pm_runtime_disable(&adev->dev);
>   err_no_irq:
>  	clk_put(pl022->clk);
>   err_no_clk:
> @@ -2271,6 +2258,12 @@ pl022_remove(struct amba_device *adev)
>  	if (!pl022)
>  		return 0;
>  
> +	/*
> +	 * undo pm_runtime_put() in probe.  I assume that we're not
> +	 * accessing the primecell here.
> +	 */
> +	pm_runtime_get_noresume(&adev->dev);
> +
>  	/* Remove the queue */
>  	if (destroy_queue(pl022) != 0)
>  		dev_err(&adev->dev, "queue remove failed\n");
> @@ -2288,10 +2281,10 @@ pl022_remove(struct amba_device *adev)
>  	return 0;
>  }
>  
> -#ifdef CONFIG_PM
> -static int pl022_suspend(struct amba_device *adev, pm_message_t state)
> +#ifdef CONFIG_SUSPEND
> +static int pl011_suspend(struct device *dev)
>  {
> -	struct pl022 *pl022 = amba_get_drvdata(adev);
> +	struct pl022 *pl022 = dev_get_drvdata(dev);
>  	int status = 0;
>  
>  	status = stop_queue(pl022);
> @@ -2300,34 +2293,58 @@ static int pl022_suspend(struct amba_device *adev, pm_message_t state)
>  		return status;
>  	}
>  
> -	amba_vcore_enable(adev);
> -	amba_pclk_enable(adev);
> +	amba_vcore_enable(pl022->adev);
> +	amba_pclk_enable(pl022->adev);
>  	load_ssp_default_config(pl022);
> -	amba_pclk_disable(adev);
> -	amba_vcore_disable(adev);
> +	amba_pclk_disable(pl022->adev);
> +	amba_vcore_disable(pl022->adev);
>  	dev_dbg(&adev->dev, "suspended\n");
>  	return 0;
>  }
>  
> -static int pl022_resume(struct amba_device *adev)
> +static int pl022_resume(struct device *dev)
>  {
> -	struct pl022 *pl022 = amba_get_drvdata(adev);
> +	struct pl022 *pl022 = dev_get_drvdata(dev);
>  	int status = 0;
>  
>  	/* Start the queue running */
>  	status = start_queue(pl022);
>  	if (status)
> -		dev_err(&adev->dev, "problem starting queue (%d)\n", status);
> +		dev_err(dev, "problem starting queue (%d)\n", status);
>  	else
> -		dev_dbg(&adev->dev, "resumed\n");
> +		dev_dbg(dev, "resumed\n");
>  
>  	return status;
>  }
> -#else
> -#define pl022_suspend NULL
> -#define pl022_resume NULL
>  #endif	/* CONFIG_PM */
>  
> +#ifdef CONFIG_PM_RUNTIME
> +static int pl022_runtime_suspend(struct device *dev)
> +{
> +	struct pl022 *pl022 = dev_get_drvdata(dev);
> +
> +	clk_disable(pl022->clk);
> +	amba_vcore_disable(pl022->adev);
> +
> +	return 0;
> +}
> +
> +static int pl022_runtime_resume(struct device *dev)
> +{
> +	struct pl022 *pl022 = dev_get_drvdata(dev);
> +
> +	amba_vcore_enable(pl022->adev);
> +	clk_enable(pl022->clk);
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops pl022_dev_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(pl022_suspend, pl022_resume)
> +	SET_RUNTIME_PM_OPS(pl022_runtime_suspend, pl022_runtime_resume, NULL)
> +};
> +
>  static struct vendor_data vendor_arm = {
>  	.fifodepth = 8,
>  	.max_bpw = 16,
> @@ -2407,12 +2424,11 @@ static struct amba_id pl022_ids[] = {
>  static struct amba_driver pl022_driver = {
>  	.drv = {
>  		.name	= "ssp-pl022",
> +		.pm	= &pl022_dev_pm_ops,
>  	},
>  	.id_table	= pl022_ids,
>  	.probe		= pl022_probe,
>  	.remove		= __devexit_p(pl022_remove),
> -	.suspend        = pl022_suspend,
> -	.resume         = pl022_resume,
>  };
>  
>  
> 

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