Subject: [PATCH] spi/atmel: add support for runtime PM

From: [email-masked] (Kevin Hilman)
Date: Fri, 17 Oct 2014 06:02:35 -0700

Wenyou Yang <[email-masked]> writes:

> Drivers should put the device into low power states proactively whenever the
> device is not in use. Thus implement support for runtime PM and use the
> autosuspend feature to make sure that we can still perform well in case we see
> lots of SPI traffic within short period of time.
>
> Signed-off-by: Wenyou Yang <[email-masked]>
> ---
>  drivers/spi/spi-atmel.c |   62 +++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 55 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index 649dcb5..aca285e 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -26,6 +26,7 @@
>  #include <linux/io.h>
>  #include <linux/gpio.h>
>  #include <linux/pinctrl/consumer.h>
> +#include <linux/pm_runtime.h>
>  
>  /* SPI register offsets */
>  #define SPI_CR					0x0000
> @@ -191,6 +192,8 @@
>  
>  #define SPI_DMA_TIMEOUT		(msecs_to_jiffies(1000))
>  
> +#define AUTOSUSPEND_TIMEOUT	2000
> +
>  struct atmel_spi_dma {
>  	struct dma_chan			*chan_rx;
>  	struct dma_chan			*chan_tx;
> @@ -1313,6 +1316,7 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	master->setup = atmel_spi_setup;
>  	master->transfer_one_message = atmel_spi_transfer_one_message;
>  	master->cleanup = atmel_spi_cleanup;
> +	master->auto_runtime_pm = true;
>  	platform_set_drvdata(pdev, master);
>  
>  	as = spi_master_get_devdata(master);
> @@ -1385,6 +1389,11 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
>  			(unsigned long)regs->start, irq);
>  
> +	pm_runtime_set_autosuspend_delay(&pdev->dev, AUTOSUSPEND_TIMEOUT);
> +	pm_runtime_use_autosuspend(&pdev->dev);
> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +
>  	ret = devm_spi_register_master(&pdev->dev, master);
>  	if (ret)
>  		goto out_free_dma;
> @@ -1392,6 +1401,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	return 0;
>  
>  out_free_dma:
> +	pm_runtime_disable(&pdev->dev);
> +	pm_runtime_set_suspended(&pdev->dev);
> +
>  	if (as->use_dma)
>  		atmel_spi_release_dma(as);
>  
> @@ -1413,6 +1425,8 @@ static int atmel_spi_remove(struct platform_device *pdev)
>  	struct spi_master	*master = platform_get_drvdata(pdev);
>  	struct atmel_spi	*as = spi_master_get_devdata(master);
>  
> +	pm_runtime_get_sync(&pdev->dev);
> +
>  	/* reset the hardware and block queue progress */
>  	spin_lock_irq(&as->lock);
>  	if (as->use_dma) {
> @@ -1430,9 +1444,13 @@ static int atmel_spi_remove(struct platform_device *pdev)
>  
>  	clk_disable_unprepare(as->clk);
>  
> +	pm_runtime_put_noidle(&pdev->dev);

Why the _noidle version?

> +	pm_runtime_disable(&pdev->dev);
> +
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PM

Why CONFIG_PM?  CONFIG_PM_SLEEP  causes CONFIG_PM=y, so this seems
redundant.

>  #ifdef CONFIG_PM_SLEEP
>  static int atmel_spi_suspend(struct device *dev)
>  {
> @@ -1447,9 +1465,10 @@ static int atmel_spi_suspend(struct device *dev)
>  		return ret;
>  	}
>  
> -	clk_disable_unprepare(as->clk);
> -
> -	pinctrl_pm_select_sleep_state(dev);
> +	if (!pm_runtime_suspended(dev)) {
> +		clk_disable_unprepare(as->clk);
> +		pinctrl_pm_select_sleep_state(dev);
> +	}

a.k.a. pm_runtime_put_sync() since the ->runtime_suspend() callback does
the same thing.

>  	return 0;
>  }
> @@ -1460,9 +1479,10 @@ static int atmel_spi_resume(struct device *dev)
>  	struct atmel_spi	*as = spi_master_get_devdata(master);
>  	int ret;
>  
> -	pinctrl_pm_select_default_state(dev);
> -
> -	clk_prepare_enable(as->clk);
> +	if (!pm_runtime_suspended(dev)) {
> +		pinctrl_pm_select_default_state(dev);
> +		clk_prepare_enable(as->clk);
> +	}

a.k.a. pm_runtime_get_sync()

Kevin

>  	/* Start the queue running */
>  	ret = spi_master_resume(master);
> @@ -1471,9 +1491,37 @@ static int atmel_spi_resume(struct device *dev)
>  
>  	return ret;
>  }
> +#endif
>  
> -static SIMPLE_DEV_PM_OPS(atmel_spi_pm_ops, atmel_spi_suspend, atmel_spi_resume);
> +#ifdef CONFIG_PM_RUNTIME
> +static int atmel_spi_runtime_suspend(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct atmel_spi *as = spi_master_get_devdata(master);
>  
> +	clk_disable_unprepare(as->clk);
> +	pinctrl_pm_select_sleep_state(dev);
> +
> +	return 0;
> +}
> +
> +static int atmel_spi_runtime_resume(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct atmel_spi *as = spi_master_get_devdata(master);
> +
> +	pinctrl_pm_select_default_state(dev);
> +	clk_prepare_enable(as->clk);
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops atmel_spi_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(atmel_spi_suspend, atmel_spi_resume)
> +	SET_RUNTIME_PM_OPS(atmel_spi_runtime_suspend,
> +			   atmel_spi_runtime_resume, NULL)
> +};
>  #define ATMEL_SPI_PM_OPS	(&atmel_spi_pm_ops)
>  #else
>  #define ATMEL_SPI_PM_OPS	NULL