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Subject[PATCH 5/6] phy: twl4030-usb: add support for reading resistor on ID pin.
From: NeilBrown <neilb@suse.de>

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.

If the read fails, which it does sometimes, try again in 50msec.

Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: NeilBrown <neilb@suse.de>
---
.../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);



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