[RFC] gpio: new driver for a gpio simulator

Message ID	20181008101356.5672-1-uwe@kleine-koenig.org
State	New
Headers	show Return-Path: <linux-gpio-owner@vger.kernel.org> From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= <uwe@kleine-koenig.org> To: Linus Walleij <linus.walleij@linaro.org> Cc: Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, kernel@pengutronix.de Subject: [PATCH RFC] gpio: new driver for a gpio simulator Date: Mon, 8 Oct 2018 12:13:56 +0200 Message-Id: <20181008101356.5672-1-uwe@kleine-koenig.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk
Series	[RFC] gpio: new driver for a gpio simulator \| expand [RFC] gpio: new driver for a gpio simulator

diff --git a/Documentation/devicetree/bindings/gpio/gpio-simulator.txt b/Documentation/devicetree/bindings/gpio/gpio-simulator.txt new file mode 100644 index 000000000000..4540b656f7c6 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-simulator.txt @@ -0,0 +1,49 @@ +GPIO simulator +============== + +This is a completely simulated device that connects the 32 GPIOs of one side +pairwise to the 32 GPIOs on the other side such that controlling a GPIO changes +the level for the matching GPIO on the other side. In hardware such a pair +would look as follows: + + ,-------. ,-------. + portA GPIO i ] ---| 100 Ω |----+----| 100 Ω |---[ portB GPIO i + `-------' | `-------' + ,---. + | 1 | + | 0 | + | k | + | Ω | + `---' + | + ⏚ + +Required properties +------------------- + +- compatible: "gpio-simulator" + +The node is expected to have two sub-nodes called "sidea" and "sideb" that +implement a gpio-controller and an interrupt-controller with 2 cells each. + + +Example: + gpiosim { + compatible = "gpio-simulator"; + + gpiosima: sidea { + gpio-controller; + #gpio-cells = <2>; + + interrupt-controller; + #interrupt-cells = <2>; + }; + + gpiosimb: sideb { + gpio-controller; + #gpio-cells = <2>; + + interrupt-controller; + #interrupt-cells = <2>; + }; + }; diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 4f52c3a8ec99..1db13cc4bedb 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -1387,4 +1387,16 @@ config GPIO_VIPERBOARD endmenu +config GPIO_SIMULATOR + tristate "GPIO simulator" + help + This provides a driver for a virtual device that exposes two banks + with 32 GPIOs each. + The virtual lines are pairwise connected, so setting the first GPIO + on the first bank as output and toggling its value makes the first GPIO + on the second bank (configured as input) change the level + accordingly. This way you can attach (say) a GPIO button device to + one of the GPIOs and "press" it by using /dev/gpioctl on the + companion GPIO. + endif diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index c256aff66a65..3560c656a984 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -111,6 +111,7 @@ obj-$(CONFIG_GPIO_REG) += gpio-reg.o obj-$(CONFIG_ARCH_SA1100) += gpio-sa1100.o obj-$(CONFIG_GPIO_SCH) += gpio-sch.o obj-$(CONFIG_GPIO_SCH311X) += gpio-sch311x.o +obj-$(CONFIG_GPIO_SIMULATOR) += gpio-simulator.o obj-$(CONFIG_GPIO_SODAVILLE) += gpio-sodaville.o obj-$(CONFIG_GPIO_SPEAR_SPICS) += gpio-spear-spics.o obj-$(CONFIG_GPIO_SPRD) += gpio-sprd.o diff --git a/drivers/gpio/gpio-simulator.c b/drivers/gpio/gpio-simulator.c new file mode 100644 index 000000000000..e8ad5539bd4a --- /dev/null +++ b/drivers/gpio/gpio-simulator.c @@ -0,0 +1,456 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/module.h> +#include <linux/gpio.h> +#include <linux/gpio/driver.h> +#include <linux/kthread.h> +#include <linux/platform_device.h> + +struct gpio_simulator_ddata; + +struct gpio_simulator_port { + struct gpio_simulator_port *other; + struct gpio_simulator_ddata *ddata; + + /* + * Each bit specifies the direction of a gpio. 1=output; 0=input + */ + u32 output; + + /* + * Each bit specifies the output value of a gpio (if the matching bit in + * .output is 1). + */ + u32 output_value; + + /* + * A one in .xxx_enable enables setting the respective bit in + * .xxx_status if the matching event happens. + */ + u32 irq_level_low_enable; + u32 irq_level_high_enable; + u32 irq_edge_falling_enable; + u32 irq_edge_raising_enable; + + /* + * .xxx_status triggers the respective irq if the matching bit in + * .irq_enable is one + */ + u32 irq_level_low_status; + u32 irq_level_high_status; + u32 irq_edge_falling_status; + u32 irq_edge_raising_status; + + u32 irq_enable; + + struct gpio_chip gchip; + struct irq_chip ichip; + + u32 level_cache; +}; + +struct gpio_simulator_ddata { + struct gpio_simulator_port port[2]; + spinlock_t lock; + struct task_struct *irqtrigger_thread; +}; + +static u32 gpio_simulator_get_pending_irq(struct gpio_simulator_port *port) +{ + u32 ret; + + ret = port->irq_enable & (port->irq_level_low_status | + port->irq_level_high_status | + port->irq_edge_falling_status | + port->irq_edge_raising_status); + + return ret; +} + +static void gpio_simulator_update_port(struct gpio_simulator_port *port) +{ + struct gpio_simulator_port *otherport = port->other; + u32 level; + + level = (port->output & port->output_value) | + (otherport->output & otherport->output_value & ~port->output); + + port->irq_level_low_status = ~level & port->irq_level_low_enable; + port->irq_level_high_status = level & port->irq_level_high_enable; + + port->irq_edge_falling_status |= + port->level_cache & ~level & port->irq_edge_falling_enable; + port->irq_edge_raising_status |= + ~port->level_cache & level & port->irq_edge_raising_enable; + + port->level_cache = level; + + if (gpio_simulator_get_pending_irq(port)) + wake_up_process(port->ddata->irqtrigger_thread); +} + +static void gpio_simulator_update(struct gpio_simulator_ddata *ddata) +{ + gpio_simulator_update_port(&ddata->port[0]); + gpio_simulator_update_port(&ddata->port[1]); +} + +static int gpio_simulator_get_direction(struct gpio_chip *chip, + unsigned int offset) +{ + struct gpio_simulator_port *port = + container_of(chip, struct gpio_simulator_port, gchip); + + if (port->output & (1 << offset)) + return GPIOF_DIR_OUT; + else + return GPIOF_DIR_IN; +} + +static int gpio_simulator_direction_input(struct gpio_chip *chip, + unsigned int offset) +{ + struct gpio_simulator_port *port = + container_of(chip, struct gpio_simulator_port, gchip); + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + port->output &= ~(1 << offset); + + gpio_simulator_update(port->ddata); + + spin_unlock_irqrestore(&port->ddata->lock, flags); + + return 0; +} + +static int gpio_simulator_direction_output(struct gpio_chip *chip, + unsigned int offset, int value) +{ + struct gpio_simulator_port *port = + container_of(chip, struct gpio_simulator_port, gchip); + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + if (value) + port->output_value |= 1 << offset; + else + port->output_value &= ~(1 << offset); + + port->output |= 1 << offset; + + gpio_simulator_update(port->ddata); + + spin_unlock_irqrestore(&port->ddata->lock, flags); + + return 0; +} + +static int gpio_simulator_get(struct gpio_chip *chip, + unsigned int offset) +{ + struct gpio_simulator_port *port = + container_of(chip, struct gpio_simulator_port, gchip); + int ret; + + ret = port->level_cache & (1 << offset); + + return ret; +} + +static void gpio_simulator_set(struct gpio_chip *chip, + unsigned int offset, int value) +{ + struct gpio_simulator_port *port = + container_of(chip, struct gpio_simulator_port, gchip); + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + if (value) + port->output_value |= 1 << offset; + else + port->output_value &= ~(1 << offset); + + gpio_simulator_update(port->ddata); + + spin_unlock_irqrestore(&port->ddata->lock, flags); +} + +static void gpio_simulator_irq_ack(struct irq_data *d) +{ + struct irq_chip *ic = irq_data_get_irq_chip(d); + struct gpio_simulator_port *port = + container_of(ic, struct gpio_simulator_port, ichip); + int level; + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + level = port->level_cache & d->mask; + if (level) + port->irq_level_low_status &= ~d->mask; + else + port->irq_level_high_status &= ~d->mask; + + port->irq_edge_raising_status &= ~d->mask; + port->irq_edge_falling_status &= ~d->mask; + + spin_unlock_irqrestore(&port->ddata->lock, flags); +} + +static void gpio_simulator_irq_mask(struct irq_data *d) +{ + struct irq_chip *ic = irq_data_get_irq_chip(d); + struct gpio_simulator_port *port = + container_of(ic, struct gpio_simulator_port, ichip); + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + port->irq_enable &= ~d->mask; + + spin_unlock_irqrestore(&port->ddata->lock, flags); +} + +static void gpio_simulator_irq_unmask(struct irq_data *d) +{ + struct irq_chip *ic = irq_data_get_irq_chip(d); + struct gpio_simulator_port *port = + container_of(ic, struct gpio_simulator_port, ichip); + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + port->irq_enable |= d->mask; + + spin_unlock_irqrestore(&port->ddata->lock, flags); +} + +static int gpio_simulator_irq_set_type(struct irq_data *d, u32 type) +{ + struct irq_chip *ic = irq_data_get_irq_chip(d); + struct gpio_simulator_port *port = + container_of(ic, struct gpio_simulator_port, ichip); + unsigned long flags; + + spin_lock_irqsave(&port->ddata->lock, flags); + + if (d->mask == 0) + d->mask = 1 << d->hwirq; + + if (type & IRQ_TYPE_EDGE_RISING) { + port->irq_edge_raising_enable |= d->mask; + } else { + port->irq_edge_raising_enable &= ~d->mask; + port->irq_edge_raising_status &= ~d->mask; + } + + if (type & IRQ_TYPE_EDGE_FALLING) { + port->irq_edge_falling_enable |= d->mask; + } else { + port->irq_edge_falling_enable &= ~d->mask; + port->irq_edge_falling_status &= ~d->mask; + } + + if (type & IRQ_TYPE_LEVEL_LOW) { + port->irq_level_low_enable |= d->mask; + } else { + port->irq_level_low_enable &= ~d->mask; + port->irq_level_low_status &= ~d->mask; + } + + if (type & IRQ_TYPE_LEVEL_HIGH) { + port->irq_level_high_enable |= d->mask; + } else { + port->irq_level_high_enable &= ~d->mask; + port->irq_level_high_status &= ~d->mask; + } + + gpio_simulator_update(port->ddata); + + spin_unlock_irqrestore(&port->ddata->lock, flags); + + return 0; +} + +static int gpio_simulator_init_port(struct platform_device *pdev, + struct gpio_simulator_ddata *ddata, + unsigned int portno, + struct device_node *of_node) +{ + struct gpio_simulator_port *here = &ddata->port[portno]; + struct gpio_simulator_port *there = &ddata->port[1 - portno]; + struct gpio_chip *gc = &here->gchip; + struct irq_chip *ic = &here->ichip; + int ret; + + here->other = there; + here->ddata = ddata; + + gc->parent = &pdev->dev; + gc->label = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s-%u", + dev_name(&pdev->dev), portno); + if (!gc->label) + return -ENOMEM; + + gc->of_node = of_node; + gc->of_gpio_n_cells = 2; + + gc->base = -1; + gc->ngpio = 32; + + gc->get_direction = gpio_simulator_get_direction; + gc->direction_input = gpio_simulator_direction_input; + gc->direction_output = gpio_simulator_direction_output; + gc->get = gpio_simulator_get; + gc->set = gpio_simulator_set; + + ic->name = gc->label; + ic->irq_ack = gpio_simulator_irq_ack; + ic->irq_mask = gpio_simulator_irq_mask; + ic->irq_unmask = gpio_simulator_irq_unmask; + ic->irq_set_type = gpio_simulator_irq_set_type; + + ret = devm_gpiochip_add_data(&pdev->dev, gc, here); + if (ret) + return ret; + + ret = gpiochip_irqchip_add(gc, ic, 0, handle_level_irq, IRQ_TYPE_NONE); + + return ret; +} + +static int gpio_simulator_irqtrigger(void *data) +{ + struct platform_device *pdev = data; + struct gpio_simulator_ddata *ddata = platform_get_drvdata(pdev); + + get_device(&pdev->dev); + + for (;;) { + u32 pending0, pending1; + int offset; + + if (kthread_should_stop()) { + put_device(&pdev->dev); + return 0; + } + + spin_lock_irq(&ddata->lock); + + pending0 = gpio_simulator_get_pending_irq(&ddata->port[0]); + pending1 = gpio_simulator_get_pending_irq(&ddata->port[1]); + + spin_unlock(&ddata->lock); + + for (offset = 0; offset < 32; ++offset) { + if (pending0 & (1 << offset)) { + struct irq_domain *irqdomain; + unsigned int irq; + + irqdomain = ddata->port[0].gchip.irq.domain; + irq = irq_find_mapping(irqdomain, offset); + + generic_handle_irq(irq); + } + + if (pending1 & (1 << offset)) { + struct irq_domain *irqdomain; + unsigned int irq; + + irq_domain = ddata->port[1].gchip.irq.domain; + irq = irq_find_mapping(irqdomain, offset); + + generic_handle_irq(irq); + } + } + + spin_lock(&ddata->lock); + + pending0 = gpio_simulator_get_pending_irq(&ddata->port[0]); + pending1 = gpio_simulator_get_pending_irq(&ddata->port[1]); + + if (!pending0 && !pending1) + set_current_state(TASK_IDLE); + + spin_unlock_irq(&ddata->lock); + + schedule(); + + set_current_state(TASK_RUNNING); + } +} + +static int gpio_simulator_probe(struct platform_device *pdev) +{ + struct gpio_simulator_ddata *ddata; + int ret; + struct device_node *of_nodea, *of_nodeb; + + ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); + if (!ddata) + return -ENOMEM; + + platform_set_drvdata(pdev, ddata); + + spin_lock_init(&ddata->lock); + + of_nodea = of_get_child_by_name(pdev->dev.of_node, "sidea"); + ret = gpio_simulator_init_port(pdev, ddata, 0, of_nodea); + if (ret) + return ret; + + of_nodeb = of_get_child_by_name(pdev->dev.of_node, "sideb"); + ret = gpio_simulator_init_port(pdev, ddata, 1, of_nodeb); + if (ret) + return ret; + + ddata->irqtrigger_thread = kthread_run(gpio_simulator_irqtrigger, pdev, + "gpiosim"); + if (IS_ERR(ddata->irqtrigger_thread)) { + dev_err(&pdev->dev, "Failed to create thread\n"); + return PTR_ERR(ddata->irqtrigger_thread); + } + + return 0; +} + +static int gpio_simulator_remove(struct platform_device *pdev) +{ + struct gpio_simulator_ddata *ddata = platform_get_drvdata(pdev); + + kthread_stop(ddata->irqtrigger_thread); + + /* + * XXX: Do I need to remove the irqchip? If yes, then .probe also needs + * an error path. + */ + + return 0; +} + +static const struct of_device_id gpio_simulator_dt_ids[] = { + { + .compatible = "gpio-simulator", + }, { + /* sentinel */ + } +}; +MODULE_DEVICE_TABLE(of, gpio_simulator_dt_ids); + +static struct platform_driver gpio_simulator_driver = { + .driver = { + .name = "gpio-simulator", + .of_match_table = gpio_simulator_dt_ids, + }, + .probe = gpio_simulator_probe, + .remove = gpio_simulator_remove, +}; +module_platform_driver(gpio_simulator_driver); + +MODULE_AUTHOR("Uwe Kleine-Koenig <uwe@kleine-koenig.org>"); +MODULE_DESCRIPTION("gpio simulator driver"); +MODULE_LICENSE("GPL v2");

[RFC] gpio: new driver for a gpio simulator

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