linux-kernel - [PATCH v7 0/2] gpio: gpio-cascade: add generic GPIO cascade

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Message-Id: <20211019200831.3817-1-maukka@ext.kapsi.fi>
Date:   Tue, 19 Oct 2021 23:08:29 +0300
From:   Mauri Sandberg <maukka@....kapsi.fi>
To:     sandberg@...lfence.com
Cc:     andy.shevchenko@...il.com, bgolaszewski@...libre.com,
        geert+renesas@...der.be, linus.walleij@...aro.org,
        linux-gpio@...r.kernel.org, robh+dt@...nel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        drew@...gleboard.org, Mauri Sandberg <maukka@....kapsi.fi>
Subject: [PATCH v7 0/2] gpio: gpio-cascade: add generic GPIO cascade

Thanks for you prompt feedback Andy. Here are the highlights on this round:
 - no changes in the bindings file.
 - added better help text in Kconfig
 - refactored the return code handling for claiming upstream gpio line
 - refactored the return and exit at the end of the function
 
Thanks,
Mauri

rangediff v6 -> v7:
1:  1283751fadd4 = 1:  434637e7188e dt-bindings: gpio-cascade: add documentation
2:  46541776733a ! 2:  a72e186f8e3b gpio: gpio-cascade: add generic GPIO cascade
    @@ Commit message
     
         Signed-off-by: Mauri Sandberg <maukka@....kapsi.fi>
         ---
    +    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
    @@ drivers/gpio/Kconfig: config GPIO_VIRTIO
     +	  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
     
    @@ drivers/gpio/gpio-cascade.c (new)
     + */
     +
     +#include <linux/module.h>
    -+#include <linux/gpio/consumer.h>
    -+#include <linux/gpio/driver.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 device		*parent;
     +	struct gpio_chip	gpio_chip;
    @@ drivers/gpio/gpio-cascade.c (new)
     +	struct mux_control *mc;
     +	struct gpio_desc *upstream;
     +	struct gpio_chip *gc;
    -+	int err;
     +
     +	cas = devm_kzalloc(dev, sizeof(*cas), GFP_KERNEL);
     +	if (!cas)
    @@ drivers/gpio/gpio-cascade.c (new)
     +
     +	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");
    ++		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)) {
    -+		dev_err(dev, "unable to claim upstream GPIO line\n");
    -+		return -ENODEV;
    -+	}
    ++	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;
    @@ drivers/gpio/gpio-cascade.c (new)
     +	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;
     +
    -+	err = devm_gpiochip_add_data(dev, &cas->gpio_chip, NULL);
    -+	if (err) {
    -+		dev_err(dev, "unable to add gpio chip\n");
    -+		return err;
    -+	}
    -+
     +	platform_set_drvdata(pdev, cas);
    -+	return 0;
    ++	return devm_gpiochip_add_data(dev, &cas->gpio_chip, NULL);
     +}
     +
     +static const struct of_device_id gpio_cascade_id[] = {

Mauri Sandberg (2):
  dt-bindings: gpio-cascade: add documentation
  gpio: gpio-cascade: add generic GPIO cascade

 .../bindings/gpio/gpio-cascade.yaml           | 103 +++++++++++++++
 drivers/gpio/Kconfig                          |  15 +++
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-cascade.c                   | 118 ++++++++++++++++++
 4 files changed, 237 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-cascade.yaml
 create mode 100644 drivers/gpio/gpio-cascade.c


base-commit: f4a20dfac88c06c9b529a41ff4cf9acba8f3fdff
-- 
2.25.1