| Message ID | 18c9e927d2b75b3325ee3eae7e78319129faa779.1513983040.git.jan.kundrat@cesnet.cz |
|---|---|
| State | New |
| Headers | show |
| Series | gpio: serial: max310x: Support open-drain configuration for GPIOs | expand |
On Fri, Dec 22, 2017 at 9:29 PM, Jan Kundrát <jan.kundrat@cesnet.cz> wrote: > 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> > --- > My suggestion is for this patch to go in via the tty/serial tree; I plan > to send more patches to this driver (and some of them are alreay in > tty-next). --jkt OK Greg can pick this. Reviewed-by: Linus Walleij <linus.walleij@linaro.org> (Looks very useful for hardware hacking, by the way.) Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Dec 22, 2017 at 09:29:44PM +0100, Jan Kundrát wrote: > 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> > --- > My suggestion is for this patch to go in via the tty/serial tree; I plan > to send more patches to this driver (and some of them are alreay in > tty-next). --jkt Doesn't apply to my tty-next branch, so I can't apply it, please rebase and resend. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c index d0e55f8456a5..c44387d0625a 100644 --- a/drivers/tty/serial/max310x.c +++ b/drivers/tty/serial/max310x.c @@ -1187,6 +1187,27 @@ 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; + } +} + static void max310x_gpio_irq_mask(struct irq_data *d) { struct gpio_chip *gc = irq_data_get_irq_chip_data(d); @@ -1426,6 +1447,7 @@ 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;
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> --- My suggestion is for this patch to go in via the tty/serial tree; I plan to send more patches to this driver (and some of them are alreay in tty-next). --jkt --- drivers/tty/serial/max310x.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)