[PATCH v2 0/3] i2c/at91: add support PM functions

[PATCH v2 0/3] i2c/at91: add support PM functions

[Wenyou Yang]

Hi Wolfram,

The patches is to add the PM functions support for the at91 i2c controller.

It is based on the i2c/for-next branch of 
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git.

Best Regards,
Wenyou Yang

------
Change log:
v2.0

According to the advice from Kevin Hilman, 
1./ Wrap the runtime suspend/resume functions in CONFIG_PM instead of CONFIG_PM_RUNTIME.
2./ Call the runtime suspend/resume functions directly in the system suspend/resume.

Wenyou Yang (3):
  i2c/at91: add support for runtime PM
  i2c/at91: add support for system PM
  i2c/at91: adopt pinctrl support

 drivers/i2c/busses/i2c-at91.c |   74 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 66 insertions(+), 8 deletions(-)

-- 
1.7.9.5

[PATCH v2 1/3] i2c/at91: add support for runtime PM

[Wenyou Yang]

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 i2c traffic within short period of time.

Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/i2c-at91.c |   42 +++++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 917d545..1b43b08 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -31,10 +31,12 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/platform_data/dma-atmel.h>
+#include <linux/pm_runtime.h>
 
 #define DEFAULT_TWI_CLK_HZ		100000		/* max 400 Kbits/s */
 #define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
 #define AT91_I2C_DMA_THRESHOLD	8			/* enable DMA if transfer size is bigger than this threshold */
+#define AUTOSUSPEND_TIMEOUT		2000
 
 /* AT91 TWI register definitions */
 #define	AT91_TWI_CR		0x0000	/* Control Register */
@@ -481,6 +483,10 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 
 	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
 
+	ret = pm_runtime_get_sync(dev->dev);
+	if (ret < 0)
+		goto out;
+
 	/*
 	 * The hardware can handle at most two messages concatenated by a
 	 * repeated start via it's internal address feature.
@@ -488,18 +494,21 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 	if (num > 2) {
 		dev_err(dev->dev,
 			"cannot handle more than two concatenated messages.\n");
-		return 0;
+		ret = 0;
+		goto out;
 	} else if (num == 2) {
 		int internal_address = 0;
 		int i;
 
 		if (msg->flags & I2C_M_RD) {
 			dev_err(dev->dev, "first transfer must be write.\n");
-			return -EINVAL;
+			ret = -EINVAL;
+			goto out;
 		}
 		if (msg->len > 3) {
 			dev_err(dev->dev, "first message size must be <= 3.\n");
-			return -EINVAL;
+			ret = -EINVAL;
+			goto out;
 		}
 
 		/* 1st msg is put into the internal address, start with 2nd */
@@ -523,7 +532,12 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 
 	ret = at91_do_twi_transfer(dev);
 
-	return (ret < 0) ? ret : num;
+	ret = (ret < 0) ? ret : num;
+out:
+	pm_runtime_mark_last_busy(dev->dev);
+	pm_runtime_put_autosuspend(dev->dev);
+
+	return ret;
 }
 
 static u32 at91_twi_func(struct i2c_adapter *adapter)
@@ -795,11 +809,20 @@ static int at91_twi_probe(struct platform_device *pdev)
 	dev->adapter.timeout = AT91_I2C_TIMEOUT;
 	dev->adapter.dev.of_node = pdev->dev.of_node;
 
+	pm_runtime_set_autosuspend_delay(dev->dev, AUTOSUSPEND_TIMEOUT);
+	pm_runtime_use_autosuspend(dev->dev);
+	pm_runtime_set_active(dev->dev);
+	pm_runtime_enable(dev->dev);
+
 	rc = i2c_add_numbered_adapter(&dev->adapter);
 	if (rc) {
 		dev_err(dev->dev, "Adapter %s registration failed\n",
 			dev->adapter.name);
 		clk_disable_unprepare(dev->clk);
+
+		pm_runtime_disable(dev->dev);
+		pm_runtime_set_suspended(dev->dev);
+
 		return rc;
 	}
 
@@ -814,6 +837,9 @@ static int at91_twi_remove(struct platform_device *pdev)
 	i2c_del_adapter(&dev->adapter);
 	clk_disable_unprepare(dev->clk);
 
+	pm_runtime_disable(dev->dev);
+	pm_runtime_set_suspended(dev->dev);
+
 	return 0;
 }
 
@@ -823,7 +849,7 @@ static int at91_twi_runtime_suspend(struct device *dev)
 {
 	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
 
-	clk_disable(twi_dev->clk);
+	clk_disable_unprepare(twi_dev->clk);
 
 	return 0;
 }
@@ -832,12 +858,12 @@ static int at91_twi_runtime_resume(struct device *dev)
 {
 	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
 
-	return clk_enable(twi_dev->clk);
+	return clk_prepare_enable(twi_dev->clk);
 }
 
 static const struct dev_pm_ops at91_twi_pm = {
-	.runtime_suspend	= at91_twi_runtime_suspend,
-	.runtime_resume		= at91_twi_runtime_resume,
+	SET_RUNTIME_PM_OPS(at91_twi_runtime_suspend,
+				at91_twi_runtime_resume, NULL)
 };
 
 #define at91_twi_pm_ops (&at91_twi_pm)
-- 
1.7.9.5

[PATCH v2 3/3] i2c/at91: adopt pinctrl support

[Wenyou Yang]

Amend the i2c at91 pin controller to optionally take a pin control
handle and set the state of the pins to:

- "default" on boot, resume and before performing an transfer
- "sleep" on suspend()

This should make it possible to optimize energy usage for the pins
both for the suspend/resume cycle

Signed-off-by: Wenyou Yang <wenyou.yang-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
Acked-by: Ludovic Desroches <ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/i2c-at91.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 8f8fd2a..7075834 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -32,6 +32,7 @@
 #include <linux/slab.h>
 #include <linux/platform_data/dma-atmel.h>
 #include <linux/pm_runtime.h>
+#include <linux/pinctrl/consumer.h>
 
 #define DEFAULT_TWI_CLK_HZ		100000		/* max 400 Kbits/s */
 #define AT91_I2C_TIMEOUT	msecs_to_jiffies(100)	/* transfer timeout */
@@ -747,6 +748,8 @@ static int at91_twi_probe(struct platform_device *pdev)
 	u32 phy_addr;
 	u32 bus_clk_rate;
 
+	pinctrl_pm_select_default_state(&pdev->dev);
+
 	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
@@ -851,6 +854,8 @@ static int at91_twi_runtime_suspend(struct device *dev)
 
 	clk_disable_unprepare(twi_dev->clk);
 
+	pinctrl_pm_select_sleep_state(dev);
+
 	return 0;
 }
 
@@ -858,6 +863,8 @@ static int at91_twi_runtime_resume(struct device *dev)
 {
 	struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
 
+	pinctrl_pm_select_default_state(dev);
+
 	return clk_prepare_enable(twi_dev->clk);
 }
 
-- 
1.7.9.5

[PATCH v2 2/3] i2c/at91: add support for system PM

[Wenyou Yang]

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
---
 drivers/i2c/busses/i2c-at91.c |   25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 1b43b08..8f8fd2a 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -861,7 +861,32 @@ static int at91_twi_runtime_resume(struct device *dev)
 	return clk_prepare_enable(twi_dev->clk);
 }
 
+static int at91_twi_suspend(struct device *dev)
+{
+	if (!pm_runtime_suspended(dev))
+		at91_twi_runtime_suspend(dev);
+
+	return 0;
+}
+
+static int at91_twi_resume(struct device *dev)
+{
+	int ret;
+
+	if (!pm_runtime_suspended(dev)) {
+		ret = at91_twi_runtime_resume(dev);
+		if (ret)
+			return ret;
+	}
+
+	pm_runtime_mark_last_busy(dev);
+	pm_request_autosuspend(dev);
+
+	return 0;
+}
+
 static const struct dev_pm_ops at91_twi_pm = {
+	SET_SYSTEM_SLEEP_PM_OPS(at91_twi_suspend, at91_twi_resume)
 	SET_RUNTIME_PM_OPS(at91_twi_runtime_suspend,
 				at91_twi_runtime_resume, NULL)
 };
-- 
1.7.9.5