diff options
Diffstat (limited to 'nixos/modules/kernel-patches/0077-gpio-gpio-cascade-add-generic-GPIO-cascade.patch')
| -rw-r--r-- | nixos/modules/kernel-patches/0077-gpio-gpio-cascade-add-generic-GPIO-cascade.patch | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/nixos/modules/kernel-patches/0077-gpio-gpio-cascade-add-generic-GPIO-cascade.patch b/nixos/modules/kernel-patches/0077-gpio-gpio-cascade-add-generic-GPIO-cascade.patch new file mode 100644 index 0000000..98dfc24 --- /dev/null +++ b/nixos/modules/kernel-patches/0077-gpio-gpio-cascade-add-generic-GPIO-cascade.patch @@ -0,0 +1,189 @@ +From f5105edd6729159f332579da5416aa3a26c84ad6 Mon Sep 17 00:00:00 2001 +From: Mauri Sandberg <maukka@ext.kapsi.fi> +Date: Thu, 25 Mar 2021 11:48:05 +0200 +Subject: [PATCH 77/96] gpio: gpio-cascade: add generic GPIO cascade + +Adds support for building cascades of GPIO lines. That is, it allows +setups when there is one upstream line and multiple cascaded lines, out +of which one can be chosen at a time. The status of the upstream line +can be conveyed to the selected cascaded line or, vice versa, the status +of the cascaded line can be conveyed to the upstream line. + +A multiplexer is being used to select, which cascaded GPIO line is being +used at any given time. + +At the moment only input direction is supported. In future it should be +possible to add support for output direction, too. + +Signed-off-by: Mauri Sandberg <maukka@ext.kapsi.fi> +Reviewed-by: Linus Walleij <linus.walleij@linaro.org> +Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> +--- + drivers/gpio/Kconfig | 15 +++++ + drivers/gpio/Makefile | 1 + + drivers/gpio/gpio-cascade.c | 117 ++++++++++++++++++++++++++++++++++++ + 3 files changed, 133 insertions(+) + create mode 100644 drivers/gpio/gpio-cascade.c + +diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig +index b01961999ced..b88980948950 100644 +--- a/drivers/gpio/Kconfig ++++ b/drivers/gpio/Kconfig +@@ -1710,4 +1710,19 @@ config GPIO_SIM + + endmenu + ++comment "Other GPIO expanders" ++ ++config GPIO_CASCADE ++ tristate "General GPIO cascade" ++ select MULTIPLEXER ++ help ++ Say yes here to enable support for generic GPIO cascade. ++ ++ This allows building one-to-many cascades of GPIO lines using ++ different types of multiplexers readily available. At the ++ moment only input lines are supported. ++ ++ To build the driver as a module choose 'm' and the resulting module ++ will be called 'gpio-cascade'. ++ + endif +diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile +index 14352f6dfe8e..561c060b0d9f 100644 +--- a/drivers/gpio/Makefile ++++ b/drivers/gpio/Makefile +@@ -44,6 +44,7 @@ obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd9571mwv.o + obj-$(CONFIG_GPIO_BRCMSTB) += gpio-brcmstb.o + obj-$(CONFIG_GPIO_BT8XX) += gpio-bt8xx.o + obj-$(CONFIG_GPIO_CADENCE) += gpio-cadence.o ++obj-$(CONFIG_GPIO_CASCADE) += gpio-cascade.o + obj-$(CONFIG_GPIO_CLPS711X) += gpio-clps711x.o + obj-$(CONFIG_GPIO_SNPS_CREG) += gpio-creg-snps.o + obj-$(CONFIG_GPIO_CRYSTAL_COVE) += gpio-crystalcove.o +diff --git a/drivers/gpio/gpio-cascade.c b/drivers/gpio/gpio-cascade.c +new file mode 100644 +index 000000000000..5cbda882d79a +--- /dev/null ++++ b/drivers/gpio/gpio-cascade.c +@@ -0,0 +1,117 @@ ++// SPDX-License-Identifier: GPL-2.0-only ++/* ++ * A generic GPIO cascade driver ++ * ++ * Copyright (C) 2021 Mauri Sandberg <maukka@ext.kapsi.fi> ++ * ++ * This allows building cascades of GPIO lines in a manner illustrated ++ * below: ++ * ++ * /|---- Cascaded GPIO line 0 ++ * Upstream | |---- Cascaded GPIO line 1 ++ * GPIO line ----+ | . ++ * | | . ++ * \|---- Cascaded GPIO line n ++ * ++ * A multiplexer is being used to select, which cascaded line is being ++ * addressed at any given time. ++ * ++ * At the moment only input mode is supported due to lack of means for ++ * testing output functionality. At least theoretically output should be ++ * possible with open drain constructions. ++ */ ++ ++#include <linux/module.h> ++#include <linux/slab.h> ++#include <linux/platform_device.h> ++#include <linux/mux/consumer.h> ++ ++#include <linux/gpio/consumer.h> ++#include <linux/gpio/driver.h> ++ ++struct gpio_cascade { ++ struct gpio_chip gpio_chip; ++ struct device *parent; ++ struct mux_control *mux_control; ++ struct gpio_desc *upstream_line; ++}; ++ ++static struct gpio_cascade *chip_to_cascade(struct gpio_chip *gc) ++{ ++ return container_of(gc, struct gpio_cascade, gpio_chip); ++} ++ ++static int gpio_cascade_get_direction(struct gpio_chip *gc, unsigned int offset) ++{ ++ return GPIO_LINE_DIRECTION_IN; ++} ++ ++static int gpio_cascade_get_value(struct gpio_chip *gc, unsigned int offset) ++{ ++ struct gpio_cascade *cas = chip_to_cascade(gc); ++ int ret; ++ ++ ret = mux_control_select(cas->mux_control, offset); ++ if (ret) ++ return ret; ++ ++ ret = gpiod_get_value(cas->upstream_line); ++ mux_control_deselect(cas->mux_control); ++ return ret; ++} ++ ++static int gpio_cascade_probe(struct platform_device *pdev) ++{ ++ struct device *dev = &pdev->dev; ++ struct gpio_cascade *cas; ++ struct mux_control *mc; ++ struct gpio_desc *upstream; ++ struct gpio_chip *gc; ++ ++ cas = devm_kzalloc(dev, sizeof(*cas), GFP_KERNEL); ++ if (!cas) ++ return -ENOMEM; ++ ++ mc = devm_mux_control_get(dev, NULL); ++ if (IS_ERR(mc)) ++ return dev_err_probe(dev, PTR_ERR(mc), "unable to get mux-control\n"); ++ ++ cas->mux_control = mc; ++ upstream = devm_gpiod_get(dev, "upstream", GPIOD_IN); ++ if (IS_ERR(upstream)) ++ return dev_err_probe(dev, PTR_ERR(upstream), "unable to claim upstream GPIO line\n"); ++ ++ cas->upstream_line = upstream; ++ cas->parent = dev; ++ ++ gc = &cas->gpio_chip; ++ gc->get = gpio_cascade_get_value; ++ gc->get_direction = gpio_cascade_get_direction; ++ gc->base = -1; ++ gc->ngpio = mux_control_states(mc); ++ gc->label = dev_name(cas->parent); ++ gc->parent = cas->parent; ++ gc->owner = THIS_MODULE; ++ ++ platform_set_drvdata(pdev, cas); ++ return devm_gpiochip_add_data(dev, &cas->gpio_chip, NULL); ++} ++ ++static const struct of_device_id gpio_cascade_id[] = { ++ { .compatible = "gpio-cascade" }, ++ { /* sentinel */ } ++}; ++MODULE_DEVICE_TABLE(of, gpio_cascade_id); ++ ++static struct platform_driver gpio_cascade_driver = { ++ .driver = { ++ .name = "gpio-cascade", ++ .of_match_table = gpio_cascade_id, ++ }, ++ .probe = gpio_cascade_probe, ++}; ++module_platform_driver(gpio_cascade_driver); ++ ++MODULE_AUTHOR("Mauri Sandberg <maukka@ext.kapsi.fi>"); ++MODULE_DESCRIPTION("Generic GPIO cascade"); ++MODULE_LICENSE("GPL"); +-- +2.37.2 + |