Messages in this thread | | | Date | Wed, 15 Jul 2015 09:42:02 +0200 | Subject | Re: [PATCH 2/2] gpio: gpio-ftdi-cbus: add driver for FTDI CBUS GPIOs | From | Linus Walleij <> |
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On Sun, Jun 21, 2015 at 12:12 AM, Stefan Agner <stefan@agner.ch> wrote:
> This driver allows to use the CBUS pins, e.g. CBUS 0-3 on FT232R > type of devices. Note that the pins need to be configured first > by using I/O mode signal option in the EEPROM. This is _not_ the > factory default configuration of any of the four pins. > > See also FTDI's Application Note AN_232R-01. > > Signed-off-by: Stefan Agner <stefan@agner.ch>
I see no big problems with this driver but I guess the serial portions are the controversial parts.
> +++ b/drivers/gpio/gpio-ftdi-cbus.c > @@ -0,0 +1,167 @@ > +/* > + * gpiolib support for FTDI SIO chips supporting CBUS GPIO's (FT232R class) > + * > + * Copyright 2015 Stefan Agner > + * > + * Author: Stefan Agner <stefan@agner.ch> > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms of the GNU General Public License as published by the > + * Free Software Foundation; either version 2 of the License, or (at your > + * option) any later version. > + * > + * Note: To use the GPIOs on CBUS the signal option need to be set to > + * I/O mode in EEPROM! > + */ > + > +#include <linux/kernel.h> > +#include <linux/slab.h> > +#include <linux/module.h> > +#include <linux/gpio.h>
#include <linux/gpio/driver.h>
should be enough.
> +static int ftdi_cbus_gpio_direction_input(struct gpio_chip *chip, > + unsigned offset) > +{ > + struct ftdi_cbus_gpio *fcg = to_ftdi_cbus_gpio(chip); > + > + fcg->cbus_mask &= ~((1 << offset) << 4);
I usually replace:
(1 << offset)
with
#include <linux/bitops.h>
BIT(offset)
so it's clear what is happening.
Yours, Linus Walleij
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