Hi Neil, Am 01.06.2015 um 23:37 schrieb NeilBrown <neilb@xxxxxxx>: > On Mon, 1 Jun 2015 19:06:52 +0530 Kishon Vijay Abraham I <kishon@xxxxxx> > wrote: > >> Hi, >> >> On Thursday 16 April 2015 01:33 PM, NeilBrown wrote: >>> From: NeilBrown <neilb@xxxxxxx> >>> >>> 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. >> >> Little sceptical about adding new sysfs entries. Do you have a good reason to >> add this? > > The hardware can report the value, so why not present it to user-space? I just had another idea how to present the value to user space. The TWL6030 has connected the USB ID pin to one of the GPADC channels: http://lxr.free-electrons.com/source/drivers/iio/adc/twl6030-gpadc.c#L235 And therefore automatically presents the ID pin voltage through iio. Would it be possible and useful to provide an iio interface for the resistance-to-ground of the tw4030 ID pin as well? This would resemble a 6 or 7 level ADC with non-linear scale, but better than nothing. And to avoid the “floating” issue, it could also present some voltage value (assuming a defined current). So that “floating” is reported as some maximum voltage (e.g. 3.3V) and “ground” as 0V. What do you think? BR, Nikolaus > > I originally used this with a udev rule which would configure the maximum > current based on the resistance measure - to work with the particular charger > 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 > > >> >> Thanks >> Kishon >>> >>> If the read fails, which it does sometimes, try again in 50msec. >>> >>> Acked-by: Pavel Machek <pavel@xxxxxx> >>> Signed-off-by: NeilBrown <neilb@xxxxxxx> >>> --- >>> .../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/Documentation/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-usb.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[] = { >>> + "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 == T2_USB_MODE_ULPI) >>> + twl4030_i2c_access(twl, 1); >>> + ret = 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 = twl4030_usb_read(twl, ID_STATUS); >>> + if (ret < 0 || (ret & 0x1f) == 0) { >>> + mdelay(50); >>> + ret = twl4030_usb_read(twl, ID_STATUS); >>> + } >>> + >>> + if (twl->usb_mode == T2_USB_MODE_ULPI) >>> + twl4030_i2c_access(twl, 0); >>> + pm_runtime_put_autosuspend(twl->dev); >>> + >>> + if (ret < 0) >>> + return TWL4030_ID_UNKNOWN; >>> + ret = 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 = 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 = 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 = _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_device *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); >>> >>> > > _______________________________________________ > Gta04-owner mailing list > Gta04-owner@xxxxxxxxxxxxx > http://lists.goldelico.com/mailman/listinfo.cgi/gta04-owner -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
