On Sat, Sep 24, 2016 at 12:50 AM, Martyn Welch
<martyn.welch@xxxxxxxxxxxxxxx> wrote:
> This patch adds support for the GPIO found on the CP2105.
> This device supports either push-pull or open-drain modes, it doesn't
> provide an explicit input mode, though the state of the GPIO can be read
> when used in open-drain mode. Like with pin use, the mode is configured in
> the one-time programable PROM and can't be changed at runtime.
I see.
So implement .direction_input() and .direction_output()
anyways.
Return failure on .direction_input() if it is in push-pull mode.
Return success on all .direction_output() calls.
Then implement .set_single_ended() and return success for open drain
if the is in open drain, success for push-pull if the line is in push-pull
mode, and failure in all other cases. Simple, but correct.
Add some comments to these functions so it is clear what is going on.
(...)
> +#ifdef CONFIG_GPIOLIB
> +static int cp210x_gpio_request(struct gpio_chip *gc, unsigned int offset)
> +{
> + struct cp210x_serial_private *priv =
> + container_of(gc, struct cp210x_serial_private, gc);
Just:
struct cp210x_serial_private *priv = gpiochip_get_data(gc);
> +static int cp210x_gpio_direction_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> + return 0;
> +}
Aha no explicit input mode...
> +static int cp210x_gpio_get(struct gpio_chip *gc, unsigned int gpio)
> +{
> + struct cp210x_serial_private *priv =
> + container_of(gc, struct cp210x_serial_private, gc);
gpiochip_get_data
> + struct usb_serial *serial = priv->serial;
> + int result;
> + u8 buf;
> +
> + result = cp210x_read_vendor_block(serial, REQTYPE_INTERFACE_TO_HOST,
> + CP210X_READ_LATCH, &buf, sizeof(buf));
> + if (result < 0)
> + return 0;
No just return the error code. We handle this nowadays.
> +
> + return (buf >> gpio) & 0x1;
Do it like this:
return !!(buf & BIT(gpio));
> +static void cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
> +{
> + struct cp210x_serial_private *priv =
> + container_of(gc, struct cp210x_serial_private, gc);
gpiochip_get_data()
(...)
+ result = gpiochip_add(&priv->gc);
Use devm_gpiochip_add_data(&serial->interface->dev, &priv->gc, gc);
And you get the pointer you need.
+void cp210x_shared_gpio_remove(struct usb_serial *serial)
+{
+ struct cp210x_serial_private *priv = usb_get_serial_data(serial);
+
+ if (priv->gc.label)
+ gpiochip_remove(&priv->gc);
+}
Should not be needed with the devm_* call above doing garbage collection.
Yours,
Linus Walleij
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