[PATCH v2 2/3] i2c: davinci: Add PM Runtime Support

[Wolfram Sang]

On Wed, Aug 16, 2017 at 05:17:14PM -0500, Franklin S Cooper Jr wrote:
> 66AK2G has I2C instances that are not apart of the ALWAYS_ON power domain
> like other Keystone 2 SoCs and OMAPL138. Therefore, pm_runtime
> is required to insure the power domain used by the specific I2C instance is
> properly turned on along with its functional clock.
> 
> Signed-off-by: Franklin S Cooper Jr <fcooper at ti.com>

I'd need a review from the driver maintainers here. Which are Sekhar
Nori and Kevin Hilman(?) according to MAINTAINERS. Is that still
correct?

> ---
> Version 2 changes:
> Move initial calls to pm runtime autosuspend before pm_runtime_enable
> 
>  drivers/i2c/busses/i2c-davinci.c | 62 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 54 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> index b8c4353..6b1930d 100644
> --- a/drivers/i2c/busses/i2c-davinci.c
> +++ b/drivers/i2c/busses/i2c-davinci.c
> @@ -36,6 +36,7 @@
>  #include <linux/gpio.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_data/i2c-davinci.h>
> +#include <linux/pm_runtime.h>
>  
>  /* ----- global defines ----------------------------------------------- */
>  
> @@ -122,6 +123,9 @@
>  /* set the SDA GPIO low */
>  #define DAVINCI_I2C_DCLR_PDCLR1	BIT(1)
>  
> +/* timeout for pm runtime autosuspend */
> +#define DAVINCI_I2C_PM_TIMEOUT	1000	/* ms */
> +
>  struct davinci_i2c_dev {
>  	struct device           *dev;
>  	void __iomem		*base;
> @@ -541,10 +545,17 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  
>  	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
>  
> +	ret = pm_runtime_get_sync(dev->dev);
> +	if (ret < 0) {
> +		dev_err(dev->dev, "Failed to runtime_get device: %d\n", ret);
> +		pm_runtime_put_noidle(dev->dev);
> +		return ret;
> +	}
> +
>  	ret = i2c_davinci_wait_bus_not_busy(dev);
>  	if (ret < 0) {
>  		dev_warn(dev->dev, "timeout waiting for bus ready\n");
> -		return ret;
> +		goto out;
>  	}
>  
>  	for (i = 0; i < num; i++) {
> @@ -552,14 +563,19 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  		dev_dbg(dev->dev, "%s [%d/%d] ret: %d\n", __func__, i + 1, num,
>  			ret);
>  		if (ret < 0)
> -			return ret;
> +			goto out;
>  	}
>  
> +	ret = num;
>  #ifdef CONFIG_CPU_FREQ
>  	complete(&dev->xfr_complete);
>  #endif
>  
> -	return num;
> +out:
> +	pm_runtime_mark_last_busy(dev->dev);
> +	pm_runtime_put_autosuspend(dev->dev);
> +
> +	return ret;
>  }
>  
>  static u32 i2c_davinci_func(struct i2c_adapter *adap)
> @@ -599,6 +615,9 @@ static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id)
>  	int count = 0;
>  	u16 w;
>  
> +	if (pm_runtime_suspended(dev->dev))
> +		return IRQ_NONE;
> +
>  	while ((stat = davinci_i2c_read_reg(dev, DAVINCI_I2C_IVR_REG))) {
>  		dev_dbg(dev->dev, "%s: stat=0x%x\n", __func__, stat);
>  		if (count++ == 100) {
> @@ -802,7 +821,6 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  	dev->clk = devm_clk_get(&pdev->dev, NULL);
>  	if (IS_ERR(dev->clk))
>  		return PTR_ERR(dev->clk);
> -	clk_prepare_enable(dev->clk);
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	dev->base = devm_ioremap_resource(&pdev->dev, mem);
> @@ -811,6 +829,18 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  		goto err_unuse_clocks;
>  	}
>  
> +	pm_runtime_set_autosuspend_delay(dev->dev,
> +					 DAVINCI_I2C_PM_TIMEOUT);
> +	pm_runtime_use_autosuspend(dev->dev);
> +
> +	pm_runtime_enable(dev->dev);
> +
> +	r = pm_runtime_get_sync(dev->dev);
> +	if (r < 0) {
> +		dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
> +		goto err_unuse_clocks;
> +	}
> +
>  	i2c_davinci_init(dev);
>  
>  	r = devm_request_irq(&pdev->dev, dev->irq, i2c_davinci_isr, 0,
> @@ -849,10 +879,16 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  	if (r)
>  		goto err_unuse_clocks;
>  
> +	pm_runtime_mark_last_busy(dev->dev);
> +	pm_runtime_put_autosuspend(dev->dev);
> +
>  	return 0;
>  
>  err_unuse_clocks:
> -	clk_disable_unprepare(dev->clk);
> +	pm_runtime_dont_use_autosuspend(dev->dev);
> +	pm_runtime_put_sync(dev->dev);
> +	pm_runtime_disable(dev->dev);
> +
>  	dev->clk = NULL;
>  	return r;
>  }
> @@ -860,16 +896,26 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>  static int davinci_i2c_remove(struct platform_device *pdev)
>  {
>  	struct davinci_i2c_dev *dev = platform_get_drvdata(pdev);
> +	int ret;
>  
>  	i2c_davinci_cpufreq_deregister(dev);
>  
>  	i2c_del_adapter(&dev->adapter);
>  
> -	clk_disable_unprepare(dev->clk);
> +	ret = pm_runtime_get_sync(&pdev->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(&pdev->dev);
> +		return ret;
> +	}
> +
>  	dev->clk = NULL;
>  
>  	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, 0);
>  
> +	pm_runtime_dont_use_autosuspend(dev->dev);
> +	pm_runtime_put_sync(dev->dev);
> +	pm_runtime_disable(dev->dev);
> +
>  	return 0;
>  }
>  
> @@ -880,7 +926,6 @@ static int davinci_i2c_suspend(struct device *dev)
>  
>  	/* put I2C into reset */
>  	davinci_i2c_reset_ctrl(i2c_dev, 0);
> -	clk_disable_unprepare(i2c_dev->clk);
>  
>  	return 0;
>  }
> @@ -889,7 +934,6 @@ static int davinci_i2c_resume(struct device *dev)
>  {
>  	struct davinci_i2c_dev *i2c_dev = dev_get_drvdata(dev);
>  
> -	clk_prepare_enable(i2c_dev->clk);
>  	/* take I2C out of reset */
>  	davinci_i2c_reset_ctrl(i2c_dev, 1);
>  
> @@ -899,6 +943,8 @@ static int davinci_i2c_resume(struct device *dev)
>  static const struct dev_pm_ops davinci_i2c_pm = {
>  	.suspend        = davinci_i2c_suspend,
>  	.resume         = davinci_i2c_resume,
> +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +				      pm_runtime_force_resume)
>  };
>  
>  #define davinci_i2c_pm_ops (&davinci_i2c_pm)
> -- 
> 2.9.4.dirty
> 
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