Hello.
On 11/10/2015 2:52 AM, Chanwoo Choi wrote:
I received the reply from you after too long time (17~18day).
You better to reply it more a little more quickly
if you have the question or new patches.
I've replied as soon as I had my new idea.
MAX3355E chip integrates a charge pump and comparators to enable a system with
an integrated USB OTG dual-role transceiver to function as a USB OTG dual-role
device. In addition to sensing/controlling Vbus, the chip also passes thru the
ID signal from the USB OTG connector. On some Renesas boards, this signal is
just fed into the SoC thru a GPIO pin -- there's no real OTG controller, only
host and gadget USB controllers sharing the same USB bus; however, we'd like
to allow host or gadget drivers to be loaded depending on the cable type,
hence
the need for the MAX3355 extcon driver. The Vbus status signals are also wired
to GPIOs (however, we're not currently intested in them), the OFFVBUS# signal
is controlled by the host controllers, there's also the SHDN# signal wired to
GPIO, which should be high for normal operation.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
---
The patch is against the 'extcon-next' branch of the 'extcon.git' repo.
Documentation/devicetree/bindings/extcon/extcon-max3355.txt | 21 ++
drivers/extcon/Kconfig | 6
drivers/extcon/Makefile | 1
drivers/extcon/extcon-max3355.c | 122
++++++++++++
4 files changed, 150 insertions(+)
Index: extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
===================================================================
--- /dev/null
+++ extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
@@ -0,0 +1,21 @@
+MAX3355 USB OTG chip
Need manufactor information as following :
-> Maxim MAX3355
Would be Maxim enough? Or perhaps I should use Maxim Integrated [Products]?
You haven't replied to my questions.
+--------------------
+
+MAX3355 integrates a charge pump and comparators to enable a system with an
+integrated USB OTG dual-role transceiver to function as a USB OTG dual-role
+device.
+
+Required properties:
+- compatible: should be "maxim,max3355";
+- maxim,shdn-gpio: should contain a phandle and GPIO specifier for the
GPIO pin
+ connected to the MAX3355's SHDN# pin;
+- maxim,id-gpio: should contain a phandle and GPIO specifier for the GPIO pin
+ connected to the MAX3355's ID_OUT pin.
+
+Example (Koelsch board):
+
+ usb-otg {
+ compatible = "maxim,max3355";
+ maxim,shdn-gpio = <&gpio2 4 GPIO_ACTIVE_LOW>;
+ maxim,id-gpio = <&gpio5 31 GPIO_ACTIVE_HIGH>;
Kernel already supported the gpio helper function to get gpio from devicetree.
I prefer use follwoing style by using of_get_gpio()/of_get_gpio_flags() in
include/linux/of_gpio.h.
gpios = <&gpio2 4 GPIO_ACTIVE_LOW>, <&gpio5 31 GPIO_ACTIVE_HIGH>;
OK, though Documentation/devicetree/bindings/gpio/gpio.txt does not seem
to insist on using this one...
Moreover, it now says "gpios" isn't allowed for the new bindings. So I have to strongly disagree here...
OK. But, I recommend you use the 'gpiod' with devm_gpiod_get
instead of using devm_gpio_request_one() directly as following:
You can refer drivers/extcon/extcon-usb-gpio.c about using gpiod.
For example,
data->shdn_gpiod = devm_gpiod_get(dev, "maxim,shdn", GPIOD_IN);
data->id_gpiod = devm_gpiod_get(dev, "maxim,id", GPIOD_IN);
Thanks, done now. I just had another idea: how about I add an optional "enable-gpio" property to the 'extcon-usb-gpio' driver? I wouldn't need my own driver then at all... :-)
What is meaning of 'enable-gpio' property?
You better to explain your goal about 'enable-gpio' property
This optional property would serve for enabling the valid signal on the ID
GPIO, the same way I'm using the SHDN# GPIO in the MAX3355 driver.
Also, If you think that it is generic way about
adding 'enable-gpio' property to extcon-usb-gpio.c,
you can try it.
Yes, I think it would be generic enough.
Thanks,
Chanwoo Choi
MBR, Sergei
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