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Message-ID: <562685EF.7010504@cogentembedded.com> Date: Tue, 20 Oct 2015 21:20:31 +0300 From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com> To: Chanwoo Choi <cw00.choi@...sung.com> Cc: robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com, ijc+devicetree@...lion.org.uk, galak@...eaurora.org, myungjoo.ham@...sung.com, grant.likely@...aro.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org, linux-usb@...r.kernel.org Subject: Re: [PATCH] extcon: add MAX3355 driver Hello. On 12/18/2014 12:58 AM, Sergei Shtylyov wrote: >>> 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@...entembedded.com> > >>> --- >>> 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... [...] >>> +static irqreturn_t max3355_id_irq(int irq, void *dev_id) >>> +{ >>> + struct max3355_data *data = dev_id; >>> + int id = gpio_get_value(data->id_gpio); >>> + >>> + extcon_set_cable_state(data->edev, "USB-HOST", !id); > >> You have to get the gpio flag in the devicetree by using of_get_gpio_flags() >> function >> and then you would set the cable state according to gpio state and flag. > > I'm sorry but I just don't see why I have to do it. This is not a generic > GPIO driver, and the polarities of the GPIOs are determined solely by the > MAX3355 specs. Again, got not reply... > [...] >>> +static int max3355_probe(struct platform_device *pdev) >>> +{ >>> + struct device_node *np = pdev->dev.of_node; >>> + struct max3355_data *data; >>> + int gpio, irq, ret; >>> + >>> + data = devm_kzalloc(&pdev->dev, sizeof(struct max3355_data), >>> + GFP_KERNEL); >>> + if (!data) >>> + return -ENOMEM; >>> + >>> + data->edev = devm_extcon_dev_allocate(&pdev->dev, max3355_cable); >>> + if (IS_ERR(data->edev)) { >>> + dev_err(&pdev->dev, "failed to allocate extcon device\n"); >>> + return PTR_ERR(data->edev); >>> + } >>> + data->edev->name = kstrdup(np->name, GFP_KERNEL); >>> + >>> + gpio = of_get_named_gpio(np, "maxim,id-gpio", 0); > >> Use of_get_gpio() or of_get_gpio_flags(). > > OK, I'll use the first one. No, I won't due to not being able to use "gpios" anymore. [...] >>> + >>> + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, max3355_id_irq, >>> + IRQF_TRIGGER_RISING | >>> + IRQF_TRIGGER_FALLING | IRQF_ONESHOT, > >> Is it right to add both RISING and FALLING trigger? > > How else I'm supposed to know when the OTG ID signal goes low and high? > >> and need to add IRQF_NO_SUSPEND to wakeup from suspend state when interrupt >> happen. > > Hm, are you sure we want to wake up on plugging another kind of USB cable? No reply to that as well... [...] >>> +static struct platform_driver max3355_driver = { >>> + .probe = max3355_probe, >>> + .driver = { >>> + .name = "extcon-max3355", >>> + .of_match_table = max3355_match_table, >>> + .owner = THIS_MODULE, >>> + }, >>> +}; >>> + >>> +module_platform_driver(max3355_driver); >>> + > >> Don't need un-used blank line. > > I don't understand. There's empty line in such case in extcon-gpio.c... No reply... [...] >> Thanks, >> Chanwoo Choi MBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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