Messages in this thread | | | Date | Thu, 18 Dec 2014 00:58:01 +0300 | From | Sergei Shtylyov <> | Subject | Re: [PATCH] extcon: add MAX3355 driver |
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Hello.
On 12/17/2014 03:31 AM, Chanwoo Choi 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@cogentembedded.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]?
>> +-------------------- >> + >> +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...
[...]
>> Index: extcon/drivers/extcon/extcon-max3355.c >> =================================================================== >> --- /dev/null >> +++ extcon/drivers/extcon/extcon-max3355.c >> @@ -0,0 +1,122 @@ >> +/* >> + * MAX3355 USB OTG chip extcon driver
> ditto.
OK, though the other Maxim extcon drivers don't serve as a good example 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.
[...] >> +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.
> "maxim,id-gpio" property has strong dependency on this driver and it is not standard.
I indented it to be Maxim specific. Not sure what using the standard property buys...
>> + if (gpio < 0) >> + return gpio;
> Need to add error message.
OK for all cases; extcon-gpio.c was probably a bad example...
[...]
>> + >> + ret = devm_gpio_request_one(&pdev->dev, gpio, GPIOF_DIR_OUT | >> + GPIOF_INIT_HIGH, pdev->name); >> + if (ret < 0) >> + return ret;
> Need to add error message.
>> + >> + ret = devm_gpio_request_one(&pdev->dev, data->id_gpio, GPIOF_DIR_IN, >> + pdev->name);
> Why do you use same name for two gpio when devm_gpio_request_one? > I prefer to use other name because two gpio is different.
And you're absolutely right here. Mindlessly copy-pasted the code from extcon-gpio.c...
[...]
>> + >> + 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?
[...] >> +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...
>> +MODULE_AUTHOR("Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>"); >> +MODULE_DESCRIPTION("MAX3355 extcon driver");
> Maxim MAX3355.
OK, seeing it in the other Maxim drivers.
>> +MODULE_LICENSE("GPL v2");
> Thanks, > Chanwoo Choi
WBR, Sergei
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