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| author | Jan Kundrát <jan.kundrat@cesnet.cz> | 2017-12-22 21:29:44 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-09 19:36:51 +0100 |
| commit | e397824bf0953344000101dc8994e92a98add0fe (patch) | |
| tree | 325fa58249fc09ab3ee5cc1b8456801f65c2ce39 /drivers/tty | |
| parent | 7d09995dcb0577b4a56aad7f2bb56f28604e8f1a (diff) | |
| download | linux-e397824bf0953344000101dc8994e92a98add0fe.tar.gz linux-e397824bf0953344000101dc8994e92a98add0fe.tar.bz2 linux-e397824bf0953344000101dc8994e92a98add0fe.zip | |
gpio: serial: max310x: Support open-drain configuration for GPIOs
The push-pull vs. open-drain are the only supported output modes. The
inputs are always unconditionally equipped with weak pull-downs. That's
the only mode, so there's probably no point in exporting that. I wonder
if it's worthwhile to provide a custom dbg_show method to indicate the
current status of the outputs, though.
This patch and [1] for i2c-gpio together make it possible to bit-bang an
I2C bus over GPIOs of an UART which is connected via SPI :). Yes, this
is crazy, but it's fast enough (while on a 26Mhz SPI HW bus with a
dual-core 1.6GHz CPU) to drive an I2C bus at 200kHz, according to my
scope.
[1] https://patchwork.ozlabs.org/patch/852591/
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/max310x.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index 97576ff791db..39f635812077 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -1159,6 +1159,27 @@ static int max310x_gpio_direction_output(struct gpio_chip *chip, return 0; } + +static int max310x_gpio_set_config(struct gpio_chip *chip, unsigned int offset, + unsigned long config) +{ + struct max310x_port *s = gpiochip_get_data(chip); + struct uart_port *port = &s->p[offset / 4].port; + + switch (pinconf_to_config_param(config)) { + case PIN_CONFIG_DRIVE_OPEN_DRAIN: + max310x_port_update(port, MAX310X_GPIOCFG_REG, + 1 << ((offset % 4) + 4), + 1 << ((offset % 4) + 4)); + return 0; + case PIN_CONFIG_DRIVE_PUSH_PULL: + max310x_port_update(port, MAX310X_GPIOCFG_REG, + 1 << ((offset % 4) + 4), 0); + return 0; + default: + return -ENOTSUPP; + } +} #endif static int max310x_probe(struct device *dev, struct max310x_devtype *devtype, @@ -1302,6 +1323,7 @@ static int max310x_probe(struct device *dev, struct max310x_devtype *devtype, s->gpio.get = max310x_gpio_get; s->gpio.direction_output= max310x_gpio_direction_output; s->gpio.set = max310x_gpio_set; + s->gpio.set_config = max310x_gpio_set_config; s->gpio.base = -1; s->gpio.ngpio = devtype->nr * 4; s->gpio.can_sleep = 1; |