diff options
Diffstat (limited to 'Documentation/driver-api/gpio')
| -rw-r--r-- | Documentation/driver-api/gpio/board.rst | 23 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/consumer.rst | 8 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/driver.rst | 187 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/intro.rst | 6 | ||||
| -rw-r--r-- | Documentation/driver-api/gpio/using-gpio.rst | 2 |
5 files changed, 169 insertions, 57 deletions
diff --git a/Documentation/driver-api/gpio/board.rst b/Documentation/driver-api/gpio/board.rst index 191fa867826a..b33aa04f213f 100644 --- a/Documentation/driver-api/gpio/board.rst +++ b/Documentation/driver-api/gpio/board.rst @@ -6,7 +6,7 @@ This document explains how GPIOs can be assigned to given devices and functions. Note that it only applies to the new descriptor-based interface. For a description of the deprecated integer-based GPIO interface please refer to -gpio-legacy.txt (actually, there is no real mapping possible with the old +legacy.rst (actually, there is no real mapping possible with the old interface; you just fetch an integer from somewhere and request the corresponding GPIO). @@ -71,14 +71,14 @@ with the help of _DSD (Device Specific Data), introduced in ACPI 5.1:: Device (FOO) { Name (_CRS, ResourceTemplate () { - GpioIo (Exclusive, ..., IoRestrictionOutputOnly, - "\\_SB.GPI0") {15} // red - GpioIo (Exclusive, ..., IoRestrictionOutputOnly, - "\\_SB.GPI0") {16} // green - GpioIo (Exclusive, ..., IoRestrictionOutputOnly, - "\\_SB.GPI0") {17} // blue - GpioIo (Exclusive, ..., IoRestrictionOutputOnly, - "\\_SB.GPI0") {1} // power + GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionOutputOnly, + "\\_SB.GPI0", 0, ResourceConsumer) { 15 } // red + GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionOutputOnly, + "\\_SB.GPI0", 0, ResourceConsumer) { 16 } // green + GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionOutputOnly, + "\\_SB.GPI0", 0, ResourceConsumer) { 17 } // blue + GpioIo (Exclusive, PullNone, 0, 0, IoRestrictionOutputOnly, + "\\_SB.GPI0", 0, ResourceConsumer) { 1 } // power }) Name (_DSD, Package () { @@ -92,10 +92,7 @@ with the help of _DSD (Device Specific Data), introduced in ACPI 5.1:: ^FOO, 2, 0, 1, } }, - Package () { - "power-gpios", - Package () {^FOO, 3, 0, 0}, - }, + Package () { "power-gpios", Package () { ^FOO, 3, 0, 0 } }, } }) } diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst index 47869ca8ccf0..de6fc79ad6f0 100644 --- a/Documentation/driver-api/gpio/consumer.rst +++ b/Documentation/driver-api/gpio/consumer.rst @@ -4,7 +4,7 @@ GPIO Descriptor Consumer Interface This document describes the consumer interface of the GPIO framework. Note that it describes the new descriptor-based interface. For a description of the -deprecated integer-based GPIO interface please refer to gpio-legacy.txt. +deprecated integer-based GPIO interface please refer to legacy.rst. Guidelines for GPIOs consumers @@ -78,7 +78,7 @@ whether the line is configured active high or active low (see The two last flags are used for use cases where open drain is mandatory, such as I2C: if the line is not already configured as open drain in the mappings -(see board.txt), then open drain will be enforced anyway and a warning will be +(see board.rst), then open drain will be enforced anyway and a warning will be printed that the board configuration needs to be updated to match the use case. Both functions return either a valid GPIO descriptor, or an error code checkable @@ -114,7 +114,7 @@ For a function using multiple GPIOs all of those can be obtained with one call:: This function returns a struct gpio_descs which contains an array of descriptors. It also contains a pointer to a gpiolib private structure which, -if passed back to get/set array functions, may speed up I/O proocessing:: +if passed back to get/set array functions, may speed up I/O processing:: struct gpio_descs { struct gpio_array *info; @@ -270,7 +270,7 @@ driven. The same is applicable for open drain or open source output lines: those do not actively drive their output high (open drain) or low (open source), they just switch their output to a high impedance value. The consumer should not need to -care. (For details read about open drain in driver.txt.) +care. (For details read about open drain in driver.rst.) With this, all the gpiod_set_(array)_value_xxx() functions interpret the parameter "value" as "asserted" ("1") or "de-asserted" ("0"). The physical line diff --git a/Documentation/driver-api/gpio/driver.rst b/Documentation/driver-api/gpio/driver.rst index bbc53920d4dd..6baaeab79534 100644 --- a/Documentation/driver-api/gpio/driver.rst +++ b/Documentation/driver-api/gpio/driver.rst @@ -119,7 +119,7 @@ GPIO lines with debounce support Debouncing is a configuration set to a pin indicating that it is connected to a mechanical switch or button, or similar that may bounce. Bouncing means the line is pulled high/low quickly at very short intervals for mechanical -reasons. This can result in the value being unstable or irqs fireing repeatedly +reasons. This can result in the value being unstable or irqs firing repeatedly unless the line is debounced. Debouncing in practice involves setting up a timer when something happens on @@ -219,7 +219,7 @@ use a trick: when a line is set as output, if the line is flagged as open drain, and the IN output value is low, it will be driven low as usual. But if the IN output value is set to high, it will instead *NOT* be driven high, instead it will be switched to input, as input mode is high impedance, thus -achieveing an "open drain emulation" of sorts: electrically the behaviour will +achieving an "open drain emulation" of sorts: electrically the behaviour will be identical, with the exception of possible hardware glitches when switching the mode of the line. @@ -417,30 +417,68 @@ struct gpio_irq_chip inside struct gpio_chip before adding the gpio_chip. If you do this, the additional irq_chip will be set up by gpiolib at the same time as setting up the rest of the GPIO functionality. The following is a typical example of a chained cascaded interrupt handler using -the gpio_irq_chip: +the gpio_irq_chip. Note how the mask/unmask (or disable/enable) functions +call into the core gpiolib code: .. code-block:: c - /* Typical state container with dynamic irqchip */ + /* Typical state container */ struct my_gpio { struct gpio_chip gc; - struct irq_chip irq; + }; + + static void my_gpio_mask_irq(struct irq_data *d) + { + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); + irq_hw_number_t hwirq = irqd_to_hwirq(d); + + /* + * Perform any necessary action to mask the interrupt, + * and then call into the core code to synchronise the + * state. + */ + + gpiochip_disable_irq(gc, hwirq); + } + + static void my_gpio_unmask_irq(struct irq_data *d) + { + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); + irq_hw_number_t hwirq = irqd_to_hwirq(d); + + gpiochip_enable_irq(gc, hwirq); + + /* + * Perform any necessary action to unmask the interrupt, + * after having called into the core code to synchronise + * the state. + */ + } + + /* + * Statically populate the irqchip. Note that it is made const + * (further indicated by the IRQCHIP_IMMUTABLE flag), and that + * the GPIOCHIP_IRQ_RESOURCE_HELPER macro adds some extra + * callbacks to the structure. + */ + static const struct irq_chip my_gpio_irq_chip = { + .name = "my_gpio_irq", + .irq_ack = my_gpio_ack_irq, + .irq_mask = my_gpio_mask_irq, + .irq_unmask = my_gpio_unmask_irq, + .irq_set_type = my_gpio_set_irq_type, + .flags = IRQCHIP_IMMUTABLE, + /* Provide the gpio resource callbacks */ + GPIOCHIP_IRQ_RESOURCE_HELPERS, }; int irq; /* from platform etc */ struct my_gpio *g; struct gpio_irq_chip *girq; - /* Set up the irqchip dynamically */ - g->irq.name = "my_gpio_irq"; - g->irq.irq_ack = my_gpio_ack_irq; - g->irq.irq_mask = my_gpio_mask_irq; - g->irq.irq_unmask = my_gpio_unmask_irq; - g->irq.irq_set_type = my_gpio_set_irq_type; - /* Get a pointer to the gpio_irq_chip */ girq = &g->gc.irq; - girq->chip = &g->irq; + gpio_irq_chip_set_chip(girq, &my_gpio_irq_chip); girq->parent_handler = ftgpio_gpio_irq_handler; girq->num_parents = 1; girq->parents = devm_kcalloc(dev, 1, sizeof(*girq->parents), @@ -458,23 +496,60 @@ the interrupt separately and go with it: .. code-block:: c - /* Typical state container with dynamic irqchip */ + /* Typical state container */ struct my_gpio { struct gpio_chip gc; - struct irq_chip irq; + }; + + static void my_gpio_mask_irq(struct irq_data *d) + { + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); + irq_hw_number_t hwirq = irqd_to_hwirq(d); + + /* + * Perform any necessary action to mask the interrupt, + * and then call into the core code to synchronise the + * state. + */ + + gpiochip_disable_irq(gc, hwirq); + } + + static void my_gpio_unmask_irq(struct irq_data *d) + { + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); + irq_hw_number_t hwirq = irqd_to_hwirq(d); + + gpiochip_enable_irq(gc, hwirq); + + /* + * Perform any necessary action to unmask the interrupt, + * after having called into the core code to synchronise + * the state. + */ + } + + /* + * Statically populate the irqchip. Note that it is made const + * (further indicated by the IRQCHIP_IMMUTABLE flag), and that + * the GPIOCHIP_IRQ_RESOURCE_HELPER macro adds some extra + * callbacks to the structure. + */ + static const struct irq_chip my_gpio_irq_chip = { + .name = "my_gpio_irq", + .irq_ack = my_gpio_ack_irq, + .irq_mask = my_gpio_mask_irq, + .irq_unmask = my_gpio_unmask_irq, + .irq_set_type = my_gpio_set_irq_type, + .flags = IRQCHIP_IMMUTABLE, + /* Provide the gpio resource callbacks */ + GPIOCHIP_IRQ_RESOURCE_HELPERS, }; int irq; /* from platform etc */ struct my_gpio *g; struct gpio_irq_chip *girq; - /* Set up the irqchip dynamically */ - g->irq.name = "my_gpio_irq"; - g->irq.irq_ack = my_gpio_ack_irq; - g->irq.irq_mask = my_gpio_mask_irq; - g->irq.irq_unmask = my_gpio_unmask_irq; - g->irq.irq_set_type = my_gpio_set_irq_type; - ret = devm_request_threaded_irq(dev, irq, NULL, irq_thread_fn, IRQF_ONESHOT, "my-chip", g); if (ret < 0) @@ -482,7 +557,7 @@ the interrupt separately and go with it: /* Get a pointer to the gpio_irq_chip */ girq = &g->gc.irq; - girq->chip = &g->irq; + gpio_irq_chip_set_chip(girq, &my_gpio_irq_chip); /* This will let us handle the parent IRQ in the driver */ girq->parent_handler = NULL; girq->num_parents = 0; @@ -500,24 +575,63 @@ In this case the typical set-up will look like this: /* Typical state container with dynamic irqchip */ struct my_gpio { struct gpio_chip gc; - struct irq_chip irq; struct fwnode_handle *fwnode; }; - int irq; /* from platform etc */ + static void my_gpio_mask_irq(struct irq_data *d) + { + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); + irq_hw_number_t hwirq = irqd_to_hwirq(d); + + /* + * Perform any necessary action to mask the interrupt, + * and then call into the core code to synchronise the + * state. + */ + + gpiochip_disable_irq(gc, hwirq); + irq_mask_mask_parent(d); + } + + static void my_gpio_unmask_irq(struct irq_data *d) + { + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); + irq_hw_number_t hwirq = irqd_to_hwirq(d); + + gpiochip_enable_irq(gc, hwirq); + + /* + * Perform any necessary action to unmask the interrupt, + * after having called into the core code to synchronise + * the state. + */ + + irq_mask_unmask_parent(d); + } + + /* + * Statically populate the irqchip. Note that it is made const + * (further indicated by the IRQCHIP_IMMUTABLE flag), and that + * the GPIOCHIP_IRQ_RESOURCE_HELPER macro adds some extra + * callbacks to the structure. + */ + static const struct irq_chip my_gpio_irq_chip = { + .name = "my_gpio_irq", + .irq_ack = my_gpio_ack_irq, + .irq_mask = my_gpio_mask_irq, + .irq_unmask = my_gpio_unmask_irq, + .irq_set_type = my_gpio_set_irq_type, + .flags = IRQCHIP_IMMUTABLE, + /* Provide the gpio resource callbacks */ + GPIOCHIP_IRQ_RESOURCE_HELPERS, + }; + struct my_gpio *g; struct gpio_irq_chip *girq; - /* Set up the irqchip dynamically */ - g->irq.name = "my_gpio_irq"; - g->irq.irq_ack = my_gpio_ack_irq; - g->irq.irq_mask = my_gpio_mask_irq; - g->irq.irq_unmask = my_gpio_unmask_irq; - g->irq.irq_set_type = my_gpio_set_irq_type; - /* Get a pointer to the gpio_irq_chip */ girq = &g->gc.irq; - girq->chip = &g->irq; + gpio_irq_chip_set_chip(girq, &my_gpio_irq_chip); girq->default_type = IRQ_TYPE_NONE; girq->handler = handle_bad_irq; girq->fwnode = g->fwnode; @@ -528,7 +642,7 @@ In this case the typical set-up will look like this: As you can see pretty similar, but you do not supply a parent handler for the IRQ, instead a parent irqdomain, an fwnode for the hardware and -a funcion .child_to_parent_hwirq() that has the purpose of looking up +a function .child_to_parent_hwirq() that has the purpose of looking up the parent hardware irq from a child (i.e. this gpio chip) hardware irq. As always it is good to look at examples in the kernel tree for advice on how to find the required pieces. @@ -605,8 +719,9 @@ When implementing an irqchip inside a GPIO driver, these two functions should typically be called in the .irq_disable() and .irq_enable() callbacks from the irqchip. -When using the gpiolib irqchip helpers, these callbacks are automatically -assigned. +When IRQCHIP_IMMUTABLE is not advertised by the irqchip, these callbacks +are automatically assigned. This behaviour is deprecated and on its way +to be removed from the kernel. Real-Time compliance for GPIO IRQ chips diff --git a/Documentation/driver-api/gpio/intro.rst b/Documentation/driver-api/gpio/intro.rst index 2e924fb5b3d5..c9c19243b97f 100644 --- a/Documentation/driver-api/gpio/intro.rst +++ b/Documentation/driver-api/gpio/intro.rst @@ -14,12 +14,12 @@ Due to the history of GPIO interfaces in the kernel, there are two different ways to obtain and use GPIOs: - The descriptor-based interface is the preferred way to manipulate GPIOs, - and is described by all the files in this directory excepted gpio-legacy.txt. + and is described by all the files in this directory excepted legacy.rst. - The legacy integer-based interface which is considered deprecated (but still - usable for compatibility reasons) is documented in gpio-legacy.txt. + usable for compatibility reasons) is documented in legacy.rst. The remainder of this document applies to the new descriptor-based interface. -gpio-legacy.txt contains the same information applied to the legacy +legacy.rst contains the same information applied to the legacy integer-based interface. diff --git a/Documentation/driver-api/gpio/using-gpio.rst b/Documentation/driver-api/gpio/using-gpio.rst index 64c8d3f76c3a..894d88855d73 100644 --- a/Documentation/driver-api/gpio/using-gpio.rst +++ b/Documentation/driver-api/gpio/using-gpio.rst @@ -44,7 +44,7 @@ These devices will appear on the system as ``/dev/gpiochip0`` thru found in the kernel tree ``tools/gpio`` subdirectory. For structured and managed applications, we recommend that you make use of the -libgpiod_ library. This provides helper abstractions, command line utlities +libgpiod_ library. This provides helper abstractions, command line utilities and arbitration for multiple simultaneous consumers on the same GPIO chip. .. _libgpiod: https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/ |