[PATCH] net: smsc911x: add power management functions

[PATCH] net: smsc911x: add power management functions

[Daniel Mack]

This adds a power management implementation for smsc911x.c which assumes
the chips remains powered during suspend. The device is put in its D1
power saving mode.

Cc: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: Daniel Mack <daniel@caiaq.de>
---
 drivers/net/smsc911x.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 46 insertions(+), 0 deletions(-)

diff --git a/drivers/net/smsc911x.c b/drivers/net/smsc911x.c
index eb7db03..77d164e 100644
--- a/drivers/net/smsc911x.c
+++ b/drivers/net/smsc911x.c
@@ -2096,12 +2096,58 @@ out_0:
 	return retval;
 }
 
+#ifdef CONFIG_PM
+/* This implementation assumes the devices remains powered on its VDDVARIO
+ * pins during suspend. */
+
+static int smsc911x_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct net_device *dev = platform_get_drvdata(pdev);
+	struct smsc911x_data *pdata = netdev_priv(dev);
+
+	/* enable wake on LAN, energy detection and the external PME
+	 * signal. */
+	smsc911x_reg_write(pdata, PMT_CTRL,
+		PMT_CTRL_PM_MODE_D1_ | PMT_CTRL_WOL_EN_ |
+		PMT_CTRL_ED_EN_ | PMT_CTRL_PME_EN_);
+
+	return 0;
+}
+
+static int smsc911x_resume(struct platform_device *pdev)
+{
+	struct net_device *dev = platform_get_drvdata(pdev);
+	struct smsc911x_data *pdata = netdev_priv(dev);
+	unsigned int to = 100;
+
+	/* Note 3.11 from the datasheet:
+	 * 	"When the LAN9220 is in a power saving state, a write of any
+	 * 	 data to the BYTE_TEST register will wake-up the device."
+	 */
+	smsc911x_reg_write(pdata, BYTE_TEST, 0);
+
+	/* poll the READY bit in PMT_CTRL. Any other access to the device is
+	 * forbidden while this bit isn't set. Try for 100ms and return -EIO
+	 * if it failed. */
+	while (!(smsc911x_reg_read(pdata, PMT_CTRL) & PMT_CTRL_READY_) && to--)
+		udelay(1000);
+
+	return (to == 0) ? -EIO : 0;
+}
+
+#else
+#define smsc911x_suspend	NULL
+#define smsc911x_resume		NULL
+#endif
+
 static struct platform_driver smsc911x_driver = {
 	.probe = smsc911x_drv_probe,
 	.remove = smsc911x_drv_remove,
 	.driver = {
 		.name = SMSC_CHIPNAME,
 	},
+	.suspend = smsc911x_suspend,
+	.resume = smsc911x_resume,
 };
 
 /* Entry point for loading the module */
-- 
1.6.2.1

Re: [PATCH] net: smsc911x: add power management functions

[David Miller]

From: Daniel Mack <daniel@caiaq.de>
Date: Mon,  4 May 2009 19:12:02 +0200

> This adds a power management implementation for smsc911x.c which assumes
> the chips remains powered during suspend. The device is put in its D1
> power saving mode.
> 
> Cc: Steve Glendinning <steve.glendinning@smsc.com>
> Signed-off-by: Daniel Mack <daniel@caiaq.de>

Steve, is this OK?

Re: [PATCH] net: smsc911x: add power management functions

[Steve.Glendinning]

Daniel Mack <daniel@caiaq.de> wrote on 04/05/2009 18:12:02:

> This adds a power management implementation for smsc911x.c which assumes
> the chips remains powered during suspend. The device is put in its D1
> power saving mode.

[....]

> +static int smsc911x_resume(struct platform_device *pdev)
> +{
> +   struct net_device *dev = platform_get_drvdata(pdev);
> +   struct smsc911x_data *pdata = netdev_priv(dev);
> +   unsigned int to = 100;
> +
> +   /* Note 3.11 from the datasheet:
> +    *    "When the LAN9220 is in a power saving state, a write of any
> +    *     data to the BYTE_TEST register will wake-up the device."
> +    */
> +   smsc911x_reg_write(pdata, BYTE_TEST, 0);
> +
> +   /* poll the READY bit in PMT_CTRL. Any other access to the device is
> +    * forbidden while this bit isn't set. Try for 100ms and return -EIO
> +    * if it failed. */
> +   while (!(smsc911x_reg_read(pdata, PMT_CTRL) & PMT_CTRL_READY_) && 
to--)
> +      udelay(1000);
> +
> +   return (to == 0) ? -EIO : 0;
> +}

to-- should be --to, otherwise it'll end up as -1 when the loop times out
(and the error code return below won't work).  Roel Kluin recently fixed
many instances of this.

Other than that, the power saving logic looks fine.

Steve

Re: [PATCH] net: smsc911x: add power management functions

[Daniel Mack]

On Tue, May 05, 2009 at 09:37:42AM +0100, Steve.Glendinning@smsc.com wrote:
> > This adds a power management implementation for smsc911x.c which assumes
> > the chips remains powered during suspend. The device is put in its D1
> > power saving mode.
> 
> [....]
> 
> > +static int smsc911x_resume(struct platform_device *pdev)
> > +{
> > +   struct net_device *dev = platform_get_drvdata(pdev);
> > +   struct smsc911x_data *pdata = netdev_priv(dev);
> > +   unsigned int to = 100;
> > +
> > +   /* Note 3.11 from the datasheet:
> > +    *    "When the LAN9220 is in a power saving state, a write of any
> > +    *     data to the BYTE_TEST register will wake-up the device."
> > +    */
> > +   smsc911x_reg_write(pdata, BYTE_TEST, 0);
> > +
> > +   /* poll the READY bit in PMT_CTRL. Any other access to the device is
> > +    * forbidden while this bit isn't set. Try for 100ms and return -EIO
> > +    * if it failed. */
> > +   while (!(smsc911x_reg_read(pdata, PMT_CTRL) & PMT_CTRL_READY_) && 
> to--)
> > +      udelay(1000);
> > +
> > +   return (to == 0) ? -EIO : 0;
> > +}
> 
> to-- should be --to, otherwise it'll end up as -1 when the loop times out
> (and the error code return below won't work).  Roel Kluin recently fixed
> many instances of this.

Yep, that's been pointed out by Enrik Berkhan already. David Miller
offered to fix that on the fly when commiting.

> Other than that, the power saving logic looks fine.

Thanks for your review :)

Daniel