Re: [PATCH 11/11] i2c: omap: enhance pinctrl support

From: Grygorii Strashko
Date: Fri May 31 2013 - 10:59:40 EST

On 05/31/2013 01:13 PM, Hebbar Gururaja wrote:
Amend the I2C omap 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 i2c transfer
- "idle" after initial default, after resume default, and after each
i2c xfer
- "sleep" on suspend()

By optionally putting the pins into sleep state in the suspend callback
we can accomplish two things.
- One is to minimize current leakage from pins and thus save power,
- second, we can prevent the IP from driving pins output in an
uncontrolled manner, which may happen if the power domain drops the
domain regulator.

Note:
A .suspend & .resume callback is added which simply puts the pins to sleep
state upon suspend & are moved to default & idle state upon resume.

If any of the above pin states are missing in dt, a warning message
about the missing state is displayed.
If certain pin-states are not available, to remove this warning message
pass respective state name with null phandler.

(Changes based on i2c-nomadik.c)

Signed-off-by: Hebbar Gururaja <gururaja.hebbar@xxxxxx>
Cc: Tony Lindgren <tony@xxxxxxxxxxx>
Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Cc: linux-omap@xxxxxxxxxxxxxxx
Cc: linux-i2c@xxxxxxxxxxxxxxx
---
:100644 100644 e02f9e3... 588ba28... M drivers/i2c/busses/i2c-omap.c
drivers/i2c/busses/i2c-omap.c | 112 ++++++++++++++++++++++++++++++++++++++---
1 file changed, 105 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index e02f9e3..588ba28 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -214,7 +214,11 @@ struct omap_i2c_dev {
u16 westate;
u16 errata;
- struct pinctrl *pins;
+ /* Three pin states - default, idle & sleep */
+ struct pinctrl *pinctrl;
+ struct pinctrl_state *pins_default;
+ struct pinctrl_state *pins_idle;
+ struct pinctrl_state *pins_sleep;
};
static const u8 reg_map_ip_v1[] = {
@@ -641,6 +645,11 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
if (IS_ERR_VALUE(r))
goto out;
The current HWMOD framework configures PINs to enable state before enabling the device and
switch PINs to idle state after disabling the device. Why here its done in different order?
+ /* Optionaly enable pins to be muxed in and configured */
+ if (!IS_ERR(dev->pins_default))
+ if (pinctrl_select_state(dev->pinctrl, dev->pins_default))
+ dev_err(dev->dev, "could not set default pins\n");
+
r = omap_i2c_wait_for_bb(dev);
if (r < 0)
goto out;
@@ -664,7 +673,13 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
out:
pm_runtime_mark_last_busy(dev->dev);
+
pm_runtime_put_autosuspend(dev->dev);
+ /* Optionally let pins go into idle state */
+ if (!IS_ERR(dev->pins_idle))
+ if (pinctrl_select_state(dev->pinctrl, dev->pins_idle))
+ dev_err(dev->dev, "could not set pins to idle state\n");
+
return r;
}
@@ -1123,14 +1138,47 @@ omap_i2c_probe(struct platform_device *pdev)
dev->set_mpu_wkup_lat = pdata->set_mpu_wkup_lat;
}
- dev->pins = devm_pinctrl_get_select_default(&pdev->dev);
- if (IS_ERR(dev->pins)) {
- if (PTR_ERR(dev->pins) == -EPROBE_DEFER)
+ dev->pinctrl = devm_pinctrl_get(&pdev->dev);
May be struct device ->pins->p can be used instead of dev->pinctrl?
+ if (!IS_ERR(dev->pinctrl)) {
+ dev->pins_default = pinctrl_lookup_state(dev->pinctrl,
+ PINCTRL_STATE_DEFAULT);
+ if (IS_ERR(dev->pins_default))
+ dev_dbg(&pdev->dev, "could not get default pinstate\n");
+ else
+ if (pinctrl_select_state(dev->pinctrl,
+ dev->pins_default))
+ dev_err(&pdev->dev,
+ "could not set default pinstate\n");
Don't need to set Default pin state
Default pins state is applied by DD framework automatically before device probing
and stored in struct device ->pins->default_state
+
+ dev->pins_idle = pinctrl_lookup_state(dev->pinctrl,
+ PINCTRL_STATE_IDLE);
+ if (IS_ERR(dev->pins_idle))
+ dev_dbg(&pdev->dev, "could not get idle pinstate\n");
+ else
+ /* If possible, let's idle until the first transfer */
+ if (pinctrl_select_state(dev->pinctrl, dev->pins_idle))
+ dev_err(&pdev->dev,
+ "could not set idle pinstate\n");
+
+ dev->pins_sleep = pinctrl_lookup_state(dev->pinctrl,
+ PINCTRL_STATE_SLEEP);
+ if (IS_ERR(dev->pins_sleep))
+ dev_dbg(&pdev->dev, "could not get sleep pinstate\n");
+ } else {
+ if (PTR_ERR(dev->pinctrl) == -EPROBE_DEFER)
return -EPROBE_DEFER;
- dev_warn(&pdev->dev, "did not get pins for i2c error: %li\n",
- PTR_ERR(dev->pins));
- dev->pins = NULL;
+ /*
+ * Since we continue even when pinctrl node is not found,
+ * Invalidate pins as not available. This is to make sure that
+ * IS_ERR(pins_xxx) results in failure when used.
+ */
+ dev->pins_default = ERR_PTR(-ENODATA);
+ dev->pins_idle = ERR_PTR(-ENODATA);
+ dev->pins_sleep = ERR_PTR(-ENODATA);
+
+ dev_dbg(&pdev->dev, "did not get pins for i2c error: %li\n",
+ PTR_ERR(dev->pinctrl));
}
dev->dev = &pdev->dev;
@@ -1300,6 +1348,10 @@ static int omap_i2c_runtime_suspend(struct device *dev)
omap_i2c_read_reg(_dev, OMAP_I2C_STAT_REG);
}
+ if (!IS_ERR(_dev->pins_idle))
+ if (pinctrl_select_state(_dev->pinctrl, _dev->pins_idle))
+ dev_err(dev, "could not set pins to idle state\n");
+
It's done in omap_i2c_xfer
return 0;
}
@@ -1311,13 +1363,59 @@ static int omap_i2c_runtime_resume(struct device *dev)
if (!_dev->regs)
return 0;
+ /* Optionally place the pins to the default state */
+ if (!IS_ERR(_dev->pins_default))
+ if (pinctrl_select_state(_dev->pinctrl, _dev->pins_default))
+ dev_err(dev, "could not set pins to default state\n");
+
It's done in omap_i2c_xfer
__omap_i2c_init(_dev);
return 0;
}
#endif /* CONFIG_PM_RUNTIME */
+#ifdef CONFIG_PM_SLEEP
+static int omap_i2c_suspend(struct device *dev)
Please, use .suspend_noirq() - it's possible that I2C will be used
even after "device suspend" stage especially on SMP platforms((( ),
but its prohibited to use it after "suspend_noirq" stage (
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
+
+ pm_runtime_get_sync(dev);
Here is the better way to detect late I2C activities during suspending:
i2c_lock_adapter(&_dev->adapter);

/* Check for active I2C transaction */
if (atomic_read(&dev->power.usage_count) > 1) {
dev_info(dev,
"active I2C transaction detected - suspend aborted\n");
return -EBUSY;
}

i2c_unlock_adapter(&_dev->adapter);
+ if (omap_i2c_wait_for_bb(_dev) < 0) {
+ pm_runtime_put_sync(dev);
+ return -EBUSY;
+ }
+ pm_runtime_put_sync(dev);
+
+ if (!IS_ERR(_dev->pins_sleep))
+ if (pinctrl_select_state(_dev->pinctrl, _dev->pins_sleep))
+ dev_err(dev, "could not set pins to sleep state\n");
+
+ return 0;
+}
Not sure it's right - Lest assume suspend_noirq() is used here.
Then, at this point, OMAP device framework will disable device (_od_suspend_noirq()).
But PINs will be switched to IDLE state before that. Is it ok?
Possibly Kevin could clarify this point?
+
+static int omap_i2c_resume(struct device *dev)
Please, use .resume_noirq()
+{
The same is here - OMAP device framework will enable device (_od_suspend_noirq()) here.
But PINs are still in IDLE state???
+ struct platform_device *pdev = to_platform_device(dev);
+ struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
+
+ /* First go to the default state */
+ if (!IS_ERR(_dev->pins_default))
+ if (pinctrl_select_state(_dev->pinctrl, _dev->pins_default))
+ dev_err(dev, "could not set pins to default state\n");
+
+ /* Then let's idle the pins until the next transfer happens */
+ if (!IS_ERR(_dev->pins_idle))
+ if (pinctrl_select_state(_dev->pinctrl, _dev->pins_idle))
+ dev_err(dev, "could not set pins to idle state\n");
+
This is wrong - at this moment I2C device can be as in Enabled state
as in Disabled
+ return 0;
+}
+#endif
+
+
static struct dev_pm_ops omap_i2c_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(omap_i2c_suspend, omap_i2c_resume)
SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
omap_i2c_runtime_resume, NULL)
};

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