phy: mapphone-mdm6600: Add USB PHY driver for MDM6600 on Droid 4

Let's add support for the GPIO controlled USB PHY on the MDM6600 modem. It is used on some Motorola Mapphone series of phones and tablets such as Droid 4.

The MDM6600 is hardwired to the first OHCI port in the Droid 4 case, and is controlled by several GPIOs. The USB PHY is integrated into the MDM6600 device it seems. We know this as we get L3 errors from omap-usb-host if trying to use the PHY before MDM6600 is configured.

Hi Tony,

Quoted 3 lines · Tony Lindgren

Let's add support for the GPIO controlled USB PHY on the MDM6600 modem. It is used on some Motorola Mapphone series of phones and tablets such as Droid 4.

Generally PHY configuration is done for the PHYs that is connected to the USB controllers in the SoC. In that sense it differs from the usual case by programming the PHY in the device.

Quoted 4 lines

The MDM6600 is hardwired to the first OHCI port in the Droid 4 case, and is controlled by several GPIOs. The USB PHY is integrated into the MDM6600 device it seems. We know this as we get L3 errors from omap-usb-host if trying to use the PHY before MDM6600 is configured.

Do you know what phy is connected to the OHCI port. Previously we've seen for having USB devices on the board itself, phy less configurations was used.

drivers/phy/motorola/phy-mapphone-mdm6600.c

Quoted 2 lines

drivers/phy/motorola/phy-mapphone-mdm6600.c new file +0 -0

.
.
<snip>
.
.

drivers/phy/motorola/phy-mapphone-mdm6600.c line 459

Quoted 5 lines

drivers/phy/motorola/phy-mapphone-mdm6600.c new file +5 -0

+
+static int phy_mdm6600_probe(struct platform_device *pdev)
+{
+	struct phy_mdm6600 *ddata;
+	struct usb_otg *otg;

Since it is connected to a OHCI, not sure if we really need to add usb_otg here.

Let's add support for the GPIO controlled USB PHY on the MDM6600 modem. It is used on some Motorola Mapphone series of phones and tablets such as Droid 4.

The MDM6600 is hardwired to the first OHCI port in the Droid 4 case, and is controlled by several GPIOs. The USB PHY is integrated into the MDM6600 device it seems. We know this as we get L3 errors from omap-usb-host if trying to use the PHY before MDM6600 is configured.

The GPIOs controlling MDM6600 are used to power device on and off, to configure the USB start-up mode (normal mode versus USB flashing), and they also tell the state of the MDM6600 device.

The two start-up mode GPIOs are dual-purposed and used for out of band (OOB) wake-up for USB and TS 27.010 serial mux. But we need to configure the USB start-up mode first to get MDM6600 booted in the right mode to be usable in the first place.

Note that the Motorola Mapphone Linux kernel tree has a "radio-ctrl" driver for modems. But it really does not control the radio at all, it just controls the modem power and start-up mode for USB. So I came to the conclusion that we're better off having this done in the USB PHY driver. For adding support for USB flashing mode, we can later on add a kernel module option for flash_mode=1 or something similar.

Also note that currently there is no PM runtime support for the OHCI on omap variant SoCs. So for low(er) power idle states, currenty both ohci-platform and phy-mapphone-mdm6600 must be unloaded or unbound.

For reference here is what I measured for total power consumption on an idle Droid 4 with and without USB related MDM6600 modules:

idle lcd off phy-mapphone-mdm6600 ohci-platform
153mW 284mW 344mW

So it seems that MDM6600 is currently not yet idling even with it's radio turned off, but that's something that is beyond the control of this USB PHY driver. This patch does get us to the point where modem data and GPS are usable with libqmi and ModemManager for example. Voice calls need more audio driver work.

Cc [email protected]

Cc Mark Rutland <[email protected]>

Cc Marcel Partap <[email protected]>

Cc Michael Scott <[email protected]>

Cc Rob Herring <[email protected]>

Cc Sebastian Reichel <[email protected]>

Signed-off-by Tony Lindgren <[email protected]>

---

Changes since v1:
- Fixed up issues noticed by Rob and Sebastian
- Implemented wake irq handler (for debug use only for now)
- Improved error handling based on more testing

---
 .../bindings/phy/phy-mapphone-mdm6600.txt          |  30 ++

 drivers/phy/motorola/Kconfig                       |   9 +
 drivers/phy/motorola/Makefile                      |   1 +
 drivers/phy/motorola/phy-mapphone-mdm6600.c        | 556 +++++++++++++++++++++
 4 files changed, 596 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/phy/phy-mapphone-mdm6600.txt
 create mode 100644 drivers/phy/motorola/phy-mapphone-mdm6600.c