Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753988AbbFAVhx (ORCPT ); Mon, 1 Jun 2015 17:37:53 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53307 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbbFAVhn (ORCPT ); Mon, 1 Jun 2015 17:37:43 -0400 Date: Tue, 2 Jun 2015 07:37:31 +1000 From: NeilBrown To: Kishon Vijay Abraham I Cc: NeilBrown , , GTA04 owners , Tony Lindgren , Pavel Machek , Subject: Re: [PATCH 5/6] phy: twl4030-usb: add support for reading resistor on ID pin. Message-ID: <20150602073731.26edbd3b@notabene.brown> In-Reply-To: <556C5FF4.3050603@ti.com> References: <20150416075945.23307.24424.stgit@notabene.brown> <20150416080304.23307.41913.stgit@notabene.brown> <556C5FF4.3050603@ti.com> X-Mailer: Claws Mail 3.10.1-162-g4d0ed6 (GTK+ 2.24.25; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/c5FbS..w+1RzbuxIwx8jZb0"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6982 Lines: 217 --Sig_/c5FbS..w+1RzbuxIwx8jZb0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 1 Jun 2015 19:06:52 +0530 Kishon Vijay Abraham I wrote: > Hi, >=20 > On Thursday 16 April 2015 01:33 PM, NeilBrown wrote: > > From: NeilBrown > > > > The twl4030 phy can measure, with low precision, the > > resistance-to-ground of the ID pin. > > > > Add a function to read the value, and export the result > > via sysfs. >=20 > Little sceptical about adding new sysfs entries. Do you have a good reaso= n to=20 > add this? The hardware can report the value, so why not present it to user-space? I originally used this with a udev rule which would configure the maximum current based on the resistance measure - to work with the particular charg= er hardware I have. More recent patches try to do all of the max-current configuration in the kernel, so I could live without exporting the value via sysfs if that is a show-stopper. I can't see where the scepticism comes from though. It is a well defined and cleary documented feature of the hardware. Why not expose it? Thanks, NeilBrown >=20 > Thanks > Kishon > > > > If the read fails, which it does sometimes, try again in 50msec. > > > > Acked-by: Pavel Machek > > Signed-off-by: NeilBrown > > --- > > .../ABI/testing/sysfs-platform-twl4030-usb | 22 +++++++ > > drivers/phy/phy-twl4030-usb.c | 63 +++++++++++= +++++++++ > > 2 files changed, 85 insertions(+) > > > > diff --git a/Documentation/ABI/testing/sysfs-platform-twl4030-usb b/Doc= umentation/ABI/testing/sysfs-platform-twl4030-usb > > index 512c51be64ae..425d23676f8a 100644 > > --- a/Documentation/ABI/testing/sysfs-platform-twl4030-usb > > +++ b/Documentation/ABI/testing/sysfs-platform-twl4030-usb > > @@ -6,3 +6,25 @@ Description: > > Possible values: "on", "off". > > > > Changes are notified via select/poll. > > + > > +What: /sys/bus/platform/devices/*twl4030-usb/id > > +Description: > > + Read-only report on measurement of USB-OTG ID pin. > > + > > + The ID pin may be floating, grounded, or pulled to > > + ground by a resistor. > > + > > + A very course grained reading of the resistance is > > + available. The numbers given in kilo-ohms are roughly > > + the center-point of the detected range. > > + > > + Possible values are: > > + ground > > + 102k > > + 200k > > + 440k > > + floating > > + unknown > > + > > + "unknown" indicates a problem with trying to detect > > + the resistance. > > diff --git a/drivers/phy/phy-twl4030-usb.c b/drivers/phy/phy-twl4030-us= b.c > > index 3a707dd14238..1d6f3e70193e 100644 > > --- a/drivers/phy/phy-twl4030-usb.c > > +++ b/drivers/phy/phy-twl4030-usb.c > > @@ -379,6 +379,56 @@ static void twl4030_i2c_access(struct twl4030_usb = *twl, int on) > > } > > } > > > > +enum twl4030_id_status { > > + TWL4030_GROUND, > > + TWL4030_102K, > > + TWL4030_200K, > > + TWL4030_440K, > > + TWL4030_FLOATING, > > + TWL4030_ID_UNKNOWN, > > +}; > > +static char *twl4030_id_names[] =3D { > > + "ground", > > + "102k", > > + "200k", > > + "440k", > > + "floating", > > + "unknown" > > +}; > > + > > +enum twl4030_id_status twl4030_get_id(struct twl4030_usb *twl) > > +{ > > + int ret; > > + > > + pm_runtime_get_sync(twl->dev); > > + if (twl->usb_mode =3D=3D T2_USB_MODE_ULPI) > > + twl4030_i2c_access(twl, 1); > > + ret =3D twl4030_usb_read(twl, ULPI_OTG_CTRL); > > + if (ret < 0 || !(ret & ULPI_OTG_ID_PULLUP)) { > > + /* Need pull-up to read ID */ > > + twl4030_usb_set_bits(twl, ULPI_OTG_CTRL, > > + ULPI_OTG_ID_PULLUP); > > + mdelay(50); > > + } > > + ret =3D twl4030_usb_read(twl, ID_STATUS); > > + if (ret < 0 || (ret & 0x1f) =3D=3D 0) { > > + mdelay(50); > > + ret =3D twl4030_usb_read(twl, ID_STATUS); > > + } > > + > > + if (twl->usb_mode =3D=3D T2_USB_MODE_ULPI) > > + twl4030_i2c_access(twl, 0); > > + pm_runtime_put_autosuspend(twl->dev); > > + > > + if (ret < 0) > > + return TWL4030_ID_UNKNOWN; > > + ret =3D ffs(ret) - 1; > > + if (ret < TWL4030_GROUND || ret > TWL4030_FLOATING) > > + return TWL4030_ID_UNKNOWN; > > + > > + return ret; > > +} > > + > > static void __twl4030_phy_power(struct twl4030_usb *twl, int on) > > { > > u8 pwr =3D twl4030_usb_read(twl, PHY_PWR_CTRL); > > @@ -532,6 +582,16 @@ static ssize_t twl4030_usb_vbus_show(struct device= *dev, > > } > > static DEVICE_ATTR(vbus, 0444, twl4030_usb_vbus_show, NULL); > > > > +static ssize_t twl4030_usb_id_show(struct device *dev, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + struct twl4030_usb *twl =3D dev_get_drvdata(dev); > > + return scnprintf(buf, PAGE_SIZE, "%s\n", > > + twl4030_id_names[twl4030_get_id(twl)]); > > +} > > +static DEVICE_ATTR(id, 0444, twl4030_usb_id_show, NULL); > > + > > static irqreturn_t twl4030_usb_irq(int irq, void *_twl) > > { > > struct twl4030_usb *twl =3D _twl; > > @@ -709,6 +769,8 @@ static int twl4030_usb_probe(struct platform_device= *pdev) > > platform_set_drvdata(pdev, twl); > > if (device_create_file(&pdev->dev, &dev_attr_vbus)) > > dev_warn(&pdev->dev, "could not create sysfs file\n"); > > + if (device_create_file(&pdev->dev, &dev_attr_id)) > > + dev_warn(&pdev->dev, "could not create sysfs file\n"); > > > > ATOMIC_INIT_NOTIFIER_HEAD(&twl->phy.notifier); > > > > @@ -753,6 +815,7 @@ static int twl4030_usb_remove(struct platform_devic= e *pdev) > > pm_runtime_get_sync(twl->dev); > > cancel_delayed_work(&twl->id_workaround_work); > > device_remove_file(twl->dev, &dev_attr_vbus); > > + device_remove_file(twl->dev, &dev_attr_id); > > > > /* set transceiver mode to power on defaults */ > > twl4030_usb_set_mode(twl, -1); > > > > --Sig_/c5FbS..w+1RzbuxIwx8jZb0 Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIVAwUBVWzQmznsnt1WYoG5AQJvFxAArDgCT9yg3XjnYUqgnstFg7DiFcHZ/ye2 nxecgd7eRE0uBtcieLIy+EjiP7aj2GMrjocx0gcTXwNcmLhP63nvSm/L2yF+6WGi OsFrkTzVnDJtrWvudDRhcHHt54Og0C72jlR/ToObbERP2QOr8hHb0a3TiUezjG0U LlgKjH5HLFy0nws1s88ITRMMyeVyd/ZrfS7vZKZu4n1XU9gvu1JtIzBzuj0GLjjL u9bCa0MBIOOIYmgs4wDeExRx64zardsn+i88yUKK1tOFyg7B6x4gfS+1IHlNv6Kr v41IiWZ7TGIMzW5gCdJgSVP0pdJM5k+/Pr2GgmyQ4UF9yJ7QfcPryFzlfWg53NB7 t5Zr2i2EQtdOpCEk1EBVQLgLoA5//PQ5HHk6L5pFRDm9Pu2hZQSV9B13Kk77Faii knQhhC0eobCtQJZImKjhuO1JG9z0TNeipyIAKKEXqpc6amyaP+RB63J++6hg7ZKJ LM37oghZZqrg9B5lHGanBxWo41H267sDYEr+DpfCVzaTfsr/HyDUgwLgesnEs/mB 3UnaOG0u4THK4nyX/zjvcpdVyGhI1ZHcsIKEeWA7Ui5W7AcVE5xWQdUwIZItZdSJ X8nD6EYlMHUC5lxJMRcVmSzIpjvNPEJy8XoEwbdglInWyAM+uyu3N9r/KesKoYV0 KBqiXsHsp50= =0TYz -----END PGP SIGNATURE----- --Sig_/c5FbS..w+1RzbuxIwx8jZb0-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/