Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753362Ab1DQVi1 (ORCPT ); Sun, 17 Apr 2011 17:38:27 -0400 Received: from eu1sys200aog108.obsmtp.com ([207.126.144.125]:52322 "EHLO eu1sys200aog108.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751588Ab1DQViW (ORCPT ); Sun, 17 Apr 2011 17:38:22 -0400 From: Linus Walleij To: Grant Likely , , Cc: Lee Jones , Linus Walleij Subject: [PATCH 1/2] gpio: add pin biasing and drive mode to gpiolib Date: Sun, 17 Apr 2011 23:37:53 +0200 Message-ID: <1303076273-8093-1-git-send-email-linus.walleij@stericsson.com> X-Mailer: git-send-email 1.7.3.2 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6384 Lines: 187 From: Linus Walleij This adds two functions for struct gpio_chip chips to provide pin bias and drive mode settings for individual pins. Implementers does this a bit differently and usually there are a few possible modes you can select, I'm providing a few common modes for biasing and driving pins. Since we have no previous hacked-up arch-specific drivers for this we can avoid any __override_functions and we just allow this to be properly implemented using gpiolib. Further the function is made non-mandatory, if it is not defined for the chip it will be silently ignored. Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib.c | 43 ++++++++++++++++++++++++++++++++++++++ include/asm-generic/gpio.h | 12 ++++++++++ include/linux/gpio.h | 49 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 104 insertions(+), 0 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 36a2974..f79f4a3 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1573,6 +1573,49 @@ void __gpio_set_value(unsigned gpio, int value) EXPORT_SYMBOL_GPL(__gpio_set_value); /** + * gpio_set_bias() - set a gpio's bias + * @gpio: gpio whose bias will be set + * @bias: bias mode to set + * Context: process + * + * This is used to directly or indirectly to implement gpio_set_bias(). + * It invokes the associated gpio_chip.set_bias() method. Usually this + * applies to input pins. + */ +void gpio_set_bias(unsigned gpio, enum gpio_bias bias) +{ + struct gpio_chip *chip; + + chip = gpio_to_chip(gpio); + /* Implementing this is not mandatory */ + if (chip->set_bias) + chip->set_bias(chip, gpio - chip->base, bias); +} +EXPORT_SYMBOL_GPL(gpio_set_bias); + +/** + * gpio_set_drive() - set a gpio's drive mode + * @gpio: gpio whose drive mode will be set + * @drive: drive mode to set + * Context: process + * + * This is used to directly or indirectly to implement gpio_set_drive(). + * It invokes the associated gpio_chip.set_drive() method. Call this + * before the __gpio_set_output() function to enable special drive modes. + */ +void gpio_set_drive(unsigned gpio, enum gpio_drive drive) +{ + struct gpio_chip *chip; + + chip = gpio_to_chip(gpio); + /* Implementing this is not mandatory */ + if (chip->set_drive) + chip->set_drive(chip, gpio - chip->base, drive); +} +EXPORT_SYMBOL_GPL(gpio_set_drive); + + +/** * __gpio_cansleep() - report whether gpio value access will sleep * @gpio: gpio in question * Context: any diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index ff5c660..b4971b1 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -59,6 +59,8 @@ struct device_node; * returns either the value actually sensed, or zero * @direction_output: configures signal "offset" as output, or returns error * @set: assigns output value for signal "offset" + * @set_bias: set a certain bias for the GPIO + * @set_drive: set a certain drive mode for the GPIO * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; * implementation may not sleep * @dbg_show: optional routine to show contents in debugfs; default code @@ -109,6 +111,14 @@ struct gpio_chip { void (*set)(struct gpio_chip *chip, unsigned offset, int value); + void (*set_bias)(struct gpio_chip *chip, + unsigned offset, + enum gpio_bias bias); + + void (*set_drive)(struct gpio_chip *chip, + unsigned offset, + enum gpio_drive drive); + int (*to_irq)(struct gpio_chip *chip, unsigned offset); @@ -158,6 +168,8 @@ extern int gpio_set_debounce(unsigned gpio, unsigned debounce); extern int gpio_get_value_cansleep(unsigned gpio); extern void gpio_set_value_cansleep(unsigned gpio, int value); +extern void gpio_set_bias(unsigned gpio, enum gpio_bias bias); +extern void gpio_set_drive(unsigned gpio, enum gpio_drive drive); /* A platform's code may want to inline the I/O calls when * the GPIO is constant and refers to some always-present controller, diff --git a/include/linux/gpio.h b/include/linux/gpio.h index 32720ba..6b48c15 100644 --- a/include/linux/gpio.h +++ b/include/linux/gpio.h @@ -3,6 +3,43 @@ /* see Documentation/gpio.txt */ +/** + * enum gpio_bias - bias modes for GPIOs + * @GPIO_BIAS_FLOAT: no specific bias, the GPIO will float or state is no + * controlled by software + * @GPIO_BIAS_PULL_UP: the GPIO will be pulled up (usually with high impedance + * to VDD) + * @GPIO_BIAS_PULL_DOWN: the GPIO will be pulled down (usually with high + * impedance to GROUND) + * @GPIO_BIAS_HIGH: the GPIO will be wired high, connected to VDD + * @GPIO_BIAS_GROUND: the GPIO will be grounded, connected to GROUND + */ +enum gpio_bias { + GPIO_BIAS_FLOAT, + GPIO_BIAS_PULL_UP, + GPIO_BIAS_PULL_DOWN, + GPIO_BIAS_HIGH, + GPIO_BIAS_GROUND, +}; + +/** + * enum gpio_drive - drive modes for GPIOs (output) + * @GPIO_DRIVE_PUSH_PULL: the GPIO will be driven actively high and low, this + * is the most typical case and is typically achieved with two active + * transistors on the output + * @GPIO_DRIVE_OPEN_DRAIN: the GPIO will be driven with open drain (open + * collector) which means it is usually wired with other output ports + * which are then pulled up with an external resistor + * @GPIO_DRIVE_OPEN_SOURCE: the GPIO will be driven with open drain + * (open emitter) which is the same as open drain mutatis mutandis but + * pulled to ground + */ +enum gpio_drive { + GPIO_DRIVE_PUSH_PULL, + GPIO_DRIVE_OPEN_DRAIN, + GPIO_DRIVE_OPEN_SOURCE, +}; + #ifdef CONFIG_GENERIC_GPIO #include @@ -90,6 +127,18 @@ static inline void gpio_set_value(unsigned gpio, int value) WARN_ON(1); } +static inline void gpio_set_bias(unsigned gpio, enum gpio_bias bias) +{ + /* GPIO can never have been requested */ + WARN_ON(1); +} + +static inline void gpio_set_drive(unsigned gpio, enum gpio_drive drive) +{ + /* GPIO can never have been requested */ + WARN_ON(1); +} + static inline int gpio_cansleep(unsigned gpio) { /* GPIO can never have been requested or set as {in,out}put */ -- 1.7.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/