[PATCH 2/4] i2c: davinci: Add PM Runtime Support

This patch adds PM runtime support to the I2C Davinci driver.

Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Franklin S Cooper Jr <redacted>
Signed-off-by: Sekhar Nori <redacted>
---
  drivers/i2c/busses/i2c-davinci.c | 61 ++++++++++++++++++++++++++++++++++------
  1 file changed, 53 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index 5749aac..62ff869 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 +829,17 @@ static int davinci_i2c_probe(struct platform_device *pdev)
  		goto err_unuse_clocks;
  	}
  
+	pm_runtime_enable(dev->dev);
+	pm_runtime_set_autosuspend_delay(dev->dev,
+					 DAVINCI_I2C_PM_TIMEOUT);
+	pm_runtime_use_autosuspend(dev->dev);