Lines Matching +full:p +full:- +full:mos
26 between 0 and n-1, n being the number of GPIOs managed by the chip.
29 example if a system uses a memory-mapped set of I/O-registers where 32 GPIO
30 lines are handled by one bit per line in a 32-bit register, it makes sense to
44 So for example one platform could use global numbers 32-159 for GPIOs, with a
46 global numbers 0..63 with one set of GPIO controllers, 64-79 with another type
47 of GPIO controller, and on one particular board 80-95 with an FPGA. The legacy
49 2000-2063 to identify GPIO lines in a bank of I2C GPIO expanders.
60 - methods to establish GPIO line direction
61 - methods used to access GPIO line values
62 - method to set electrical configuration for a given GPIO line
63 - method to return the IRQ number associated to a given GPIO line
64 - flag saying whether calls to its methods may sleep
65 - optional line names array to identify lines
66 - optional debugfs dump method (showing extra state information)
67 - optional base number (will be automatically assigned if omitted)
68 - optional label for diagnostics and GPIO chip mapping using platform data
75 Often a gpio_chip is part of an instance-specific structure with states not
77 Chips such as audio codecs will have complex non-GPIO states.
91 -----------------------------
96 - Debouncing
97 - Single-ended modes (open drain/open source)
98 - Pull up and pull down resistor enablement
106 ending up in the pin control back-end "behind" the GPIO controller, usually
110 If a pin controller back-end is used, the GPIO controller or hardware
112 numbers on the pin controller so they can properly cross-reference each other.
116 --------------------------------
133 -----------------------------------------
137 is not open, it will present a high-impedance (tristate) to the external rail::
142 ||--- out +--- out
143 in ----|| |/
144 ||--+ in ----|
150 - Level-shifting: to reach a logical level higher than that of the silicon
153 - Inverse wire-OR on an I/O line, for example a GPIO line, making it possible
157 wire-OR bus.
159 Both use cases require that the line be equipped with a pull-up resistor. This
163 The level on the line will go as high as the VDD on the pull-up resistor, which
165 level-shift to the higher VDD.
168 "totem-pole" with one N-MOS and one P-MOS transistor where one of them drives
169 the line high and one of them drives the line low. This is called a push-pull
170 output. The "totem-pole" looks like so::
174 OD ||--+
175 +--/ ---o|| P-MOS-FET
176 | ||--+
177 IN --+ +----- out
178 | ||--+
179 +--/ ----|| N-MOS-FET
180 OS ||--+
186 a push-pull circuit.
189 P-MOS or N-MOS transistor right after the split of the input. As you can see,
190 either transistor will go totally numb if this switch is open. The totem-pole
192 high or low respectively. That is usually how software-controlled open
196 hard-wired lines that will only support open drain or open source no matter
197 what: there is only one transistor there. Some are software-configurable:
202 By disabling the P-MOS transistor, the output can be driven between GND and
203 high impedance (open drain), and by disabling the N-MOS transistor, the output
205 a pull-up resistor is needed on the outgoing rail to complete the circuit, and
206 in the second case, a pull-down resistor is needed on the rail.
211 open source or push-pull. This will happen in response to the
230 ---------------------------------------------
232 A GPIO line can support pull-up/down using the .set_config() callback. This
233 means that a pull up or pull-down resistor is available on the output of the
236 In discrete designs, a pull-up or pull-down resistor is simply soldered on
243 switch a bit in a register enabling or disabling pull-up or pull-down.
246 pull-up or pull-down resistor, the GPIO chip callback .set_config() will not
250 different pull-up or pull-down resistance values.
261 the header <linux/irq.h>. So this combined driver is utilizing two sub-
279 - CASCADED INTERRUPT CHIPS: this means that the GPIO chip has one common
292 - HIERARCHICAL INTERRUPT CHIPS: this means that each GPIO line has a dedicated
302 - spinlock_t should be replaced with raw_spinlock_t.[1]
303 - If sleepable APIs have to be used, these can be done from the .irq_bus_lock()
309 ----------------------
313 - CHAINED CASCADED GPIO IRQCHIPS: these are usually the type that is embedded on
331 threaded on -RT. As a result, spinlock_t or any sleepable APIs (like PM
336 this way it will become a threaded IRQ handler on -RT and a hard IRQ handler
337 on non-RT (for example, see [3]).
347 raw_spin_lock_irqsave(&bank->wa_lock, wa_lock_flags);
348 generic_handle_irq(irq_find_mapping(bank->chip.irq.domain, bit));
349 raw_spin_unlock_irqrestore(&bank->wa_lock, wa_lock_flags);
351 - GENERIC CHAINED GPIO IRQCHIPS: these are the same as "CHAINED GPIO irqchips",
361 Realtime considerations: this kind of handlers will be forced threaded on -RT,
363 with IRQ enabled and the same work-around as for "CHAINED GPIO irqchips" can
366 - NESTED THREADED GPIO IRQCHIPS: these are off-chip GPIO expanders and any
390 ----------------------------------------
392 To help out in handling the set-up and management of GPIO irqchips and the
397 under the assumption that your interrupts are 1-to-1-mapped to the
400 .. csv-table::
407 ngpio-1, ngpio-1
422 .. code-block:: c
479 girq = &g->gc.irq;
481 girq->parent_handler = ftgpio_gpio_irq_handler;
482 girq->num_parents = 1;
483 girq->parents = devm_kcalloc(dev, 1, sizeof(*girq->parents),
485 if (!girq->parents)
486 return -ENOMEM;
487 girq->default_type = IRQ_TYPE_NONE;
488 girq->handler = handle_bad_irq;
489 girq->parents[0] = irq;
491 return devm_gpiochip_add_data(dev, &g->gc, g);
496 .. code-block:: c
553 IRQF_ONESHOT, "my-chip", g);
558 girq = &g->gc.irq;
561 girq->parent_handler = NULL;
562 girq->num_parents = 0;
563 girq->parents = NULL;
564 girq->default_type = IRQ_TYPE_NONE;
565 girq->handler = handle_bad_irq;
567 return devm_gpiochip_add_data(dev, &g->gc, g);
570 In this case the typical set-up will look like this:
572 .. code-block:: c
632 girq = &g->gc.irq;
634 girq->default_type = IRQ_TYPE_NONE;
635 girq->handler = handle_bad_irq;
636 girq->fwnode = g->fwnode;
637 girq->parent_domain = parent;
638 girq->child_to_parent_hwirq = my_gpio_child_to_parent_hwirq;
640 return devm_gpiochip_add_data(dev, &g->gc, g);
653 bit representing line 0..n-1. Drivers can exclude GPIO lines by clearing bits
659 - Make sure to assign all relevant members of the struct gpio_chip so that
663 - Nominally set gpio_irq_chip.handler to handle_bad_irq. Then, if your irqchip
670 -----------------
685 This will prevent the use of non-irq related GPIO APIs until the GPIO IRQ lock
699 ---------------------------
726 Real-Time compliance for GPIO IRQ chips
727 ---------------------------------------
729 Any provider of irqchips needs to be carefully tailored to support Real-Time
731 in mind and do the proper testing to assure they are real time-enabled.
735 The following is a checklist to follow when preparing a driver for real-time
738 - ensure spinlock_t is not used as part irq_chip implementation
739 - ensure that sleepable APIs are not used as part irq_chip implementation
742 - Chained GPIO irqchips: ensure spinlock_t or any sleepable APIs are not used
744 - Generic chained GPIO irqchips: take care about generic_handle_irq() calls and
745 apply corresponding work-around
746 - Chained GPIO irqchips: get rid of the chained IRQ handler and use generic irq
748 - regmap_mmio: it is possible to disable internal locking in regmap by setting
750 - Test your driver with the appropriate in-kernel real-time test cases for both
753 * [1] http://www.spinics.net/lists/linux-omap/msg120425.html
754 * [2] https://lore.kernel.org/r/1443209283-20781-2-git-send-email-grygorii.strashko@ti.com
755 * [3] https://lore.kernel.org/r/1443209283-20781-3-git-send-email-grygorii.strashko@ti.com
758 Requesting self-owned GPIO pins