+++ /dev/null
-From fc23ea48ba52c24f201fe5ca0132ee1a3de5a70a 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 2/2] 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>
----
-v7 -> v8:
- - rearrange members in struct gpio_cascade
- - cosmetic changes in file header and in one function declaration
- - added Reviewed-by tags by Linus and Andy
-v6 -> v7:
- - In Kconfig add info about module name
- - adhere to new convention that allows lines longer than 80 chars
- - use dev_probe_err with upstream gpio line too
- - refactor for cleaner exit of probe function.
-v5 -> v6:
- - In Kconfig, remove dependency to OF_GPIO and select only MULTIPLEXER
- - refactor code preferring one-liners
- - clean up prints, removing them from success-path.
- - don't explicitly set gpio_chip.of_node as it's done in the GPIO library
- - use devm_gpiochip_add_data instead of gpiochip_add
-v4 -> v5:
- - renamed gpio-mux-input -> gpio-cascade. refactored code accordingly
- here and there and changed to use new bindings and compatible string
- - ambigious and vague 'pin' was rename to 'upstream_line'
- - dropped Tested-by and Reviewed-by due to changes in bindings
- - dropped Reported-by suggested by an automatic bot as it was not really
- appropriate to begin with
- - functionally it's the same as v4
-v3 -> v4:
- - Changed author email
- - Included Tested-by and Reviewed-by from Drew
-v2 -> v3:
- - use managed device resources
- - update Kconfig description
-v1 -> v2:
- - removed .owner from platform_driver as per test bot's instruction
- - added MODULE_AUTHOR, MODULE_DESCRIPTION, MODULE_LICENSE
- - added gpio_mux_input_get_direction as it's recommended for all chips
- - removed because this is input only chip: gpio_mux_input_set_value
- - removed because they are not needed for input/output only chips:
- gpio_mux_input_direction_input
- gpio_mux_input_direction_output
- - fixed typo in an error message
- - added info message about successful registration
- - removed can_sleep flag as this does not sleep while getting GPIO value
- like I2C or SPI do
- - Updated description in Kconfig
----
- 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
-
---- a/drivers/gpio/Kconfig
-+++ b/drivers/gpio/Kconfig
-@@ -1617,4 +1617,19 @@ config GPIO_MOCKUP
- tools/testing/selftests/gpio/gpio-mockup.sh. Reference the usage in
- it.
-
-+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
---- a/drivers/gpio/Makefile
-+++ b/drivers/gpio/Makefile
-@@ -44,6 +44,7 @@ obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd
- obj-$(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
---- /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");
projects / openwrt / openwrt.git / blobdiff