[PATCH 3.9 1/3] misc: new driver for GPIO-connected 7-segment displays
Grant Likely
grant.likely at secretlab.ca
Fri Feb 8 17:35:35 EST 2013
On Mon, 7 Jan 2013 17:42:06 +0100, Thomas Petazzoni <thomas.petazzoni at free-electrons.com> wrote:
> This patch adds a driver to control 7-segment displays connected over
> GPIOs through a BCD encoder. Typically, up to four GPIOs go into a BCD
> encoder, that drives the 7-segment display to display a numeric value
> between 0 and 2^ngpios-1.
>
> Once this driver is enabled, it creates a 'value' field in the sysfs
> directory of the device, which allows to set the current value
> displayed by the 7-segment.
>
> It has been successfully tested on the Marvell Armada 370 and Marvell
> Armada XP evaluation boards. Both of them have a 7-segment display
> that can be controlled using 3 GPIOs.
>
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> ---
> .../devicetree/bindings/misc/gpio-7seg.txt | 18 +++
> drivers/misc/Kconfig | 13 ++
> drivers/misc/Makefile | 1 +
> drivers/misc/gpio-7seg.c | 168 ++++++++++++++++++++
> 4 files changed, 200 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/gpio-7seg.txt
> create mode 100644 drivers/misc/gpio-7seg.c
>
> diff --git a/Documentation/devicetree/bindings/misc/gpio-7seg.txt b/Documentation/devicetree/bindings/misc/gpio-7seg.txt
> new file mode 100644
> index 0000000..107d178
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/gpio-7seg.txt
> @@ -0,0 +1,18 @@
> +* 7-segment driver connected over GPIO through a BCD decoder
> +
> +Required properties:
> +- compatible: "generic,gpio-7seg"
> +- gpios: list of GPIOs to use to control the 7-segment display
> +
> +Optional properties:
> +- default-value: default value shown by the 7-segment display at boot
> + time. If not defined, defaults to 0.
> +
> +Example:
> +
> +gpio-7seg at 0 {
> + compatible = "generic,gpio-7seg";
> + status = "okay";
> + gpios = <&gpio1 27 0 &gpio1 28 0 &gpio1 29 0>;
> + default-value = <5>;
> +};
Nice, I would use this. As an extension, I could also see wanting to
support directly attached LED displays; one GPIO per segment (but I'm
not suggesting you do that; I'm just thinking out loud).
However, rather than a completely seperate driver, can you piggyback on
the existing gpio-leds driver? It would The binding document should also be in
bindings/leds, and the driver in drivers/leds.
g.
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index b151b7c..19f9d22 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -93,6 +93,19 @@ config ATMEL_TCB_CLKSRC_BLOCK
> TC can be used for other purposes, such as PWM generation and
> interval timing.
>
> +config GPIO_7SEG
> + tristate "GPIO-connected 7-segment display driver"
> + help
> + This option enables a driver to control 7-segment displays
> + connected over GPIOs through a BCD encoder. Typically, up to
> + four GPIOs go into a BCD encoder, that drives the 7-segment
> + display to display a numeric value between 0 and
> + 2^ngpios-1.
> +
> + Once this driver is enabled, it creates a 'value' field in
> + the sysfs directory of the device, which allows to set the
> + current value displayed by the 7-segment.
> +
> config IBM_ASM
> tristate "Device driver for IBM RSA service processor"
> depends on X86 && PCI && INPUT
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index 2129377..b789358 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_INTEL_MID_PTI) += pti.o
> obj-$(CONFIG_ATMEL_PWM) += atmel_pwm.o
> obj-$(CONFIG_ATMEL_SSC) += atmel-ssc.o
> obj-$(CONFIG_ATMEL_TCLIB) += atmel_tclib.o
> +obj-$(CONFIG_GPIO_7SEG) += gpio-7seg.o
> obj-$(CONFIG_BMP085) += bmp085.o
> obj-$(CONFIG_BMP085_I2C) += bmp085-i2c.o
> obj-$(CONFIG_BMP085_SPI) += bmp085-spi.o
> diff --git a/drivers/misc/gpio-7seg.c b/drivers/misc/gpio-7seg.c
> new file mode 100644
> index 0000000..8cc5113
> --- /dev/null
> +++ b/drivers/misc/gpio-7seg.c
> @@ -0,0 +1,168 @@
> +/*
> + * Simple driver to control a 7 segment display connected through a
> + * BCD decoder using GPIOs.
> + *
> + * Copyright (C) 2012 Marvell
> + *
> + * Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/gpio.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +
> +struct gpio_7seg_dev {
> + struct device_attribute dev_attr;
> + int *gpios;
> + int ngpios;
> + int value;
> + int maxvalue;
> +};
> +
> +static void gpio_7seg_display_val(struct gpio_7seg_dev *sdev,
> + int value)
> +{
> + int i;
> +
> + for (i = 0; i < sdev->ngpios; i++) {
> + int bitval = (value & BIT(i)) ? 1 : 0;
> + gpio_set_value_cansleep(sdev->gpios[i], bitval);
> + }
> +}
> +
> +static ssize_t gpio_7seg_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct gpio_7seg_dev *sdev = dev_get_drvdata(dev);
> + return snprintf(buf, PAGE_SIZE, "%d\n", sdev->value);
> +}
> +
> +static ssize_t gpio_7seg_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct gpio_7seg_dev *sdev = dev_get_drvdata(dev);
> + unsigned long value;
> + char *end;
> +
> + value = simple_strtoul(buf, &end, 0);
> + if (end == buf)
> + return -EINVAL;
> +
> + if (value >= sdev->maxvalue)
> + return -EINVAL;
> +
> + gpio_7seg_display_val(sdev, value);
> + sdev->value = value;
> +
> + return count;
> +}
> +
> +static int gpio_7seg_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + struct gpio_7seg_dev *sdev;
> + int ret, i;
> +
> + /*
> + * We only support being probed through the device tree, for
> + * now
> + */
> + if (!np)
> + return -EINVAL;
> +
> + sdev = devm_kzalloc(&pdev->dev, sizeof(struct gpio_7seg_dev),
> + GFP_KERNEL);
> + if (!sdev)
> + return -ENOMEM;
> +
> + sdev->ngpios = of_gpio_count(np);
> + if (!sdev->ngpios)
> + return -EINVAL;
> +
> + sdev->gpios = devm_kzalloc(&pdev->dev, sizeof(int) * sdev->ngpios,
> + GFP_KERNEL);
> + if (!sdev->gpios)
> + return -ENOMEM;
> +
> + for (i = 0; i < sdev->ngpios; i++) {
> + sdev->gpios[i] = of_get_gpio(np, i);
> + ret = gpio_request_one(sdev->gpios[i], GPIOF_DIR_OUT, NULL);
> + if (ret) {
> + /*
> + * Mark this GPIO as non-requested for the
> + * error handling code
> + */
> + sdev->gpios[i] = ret;
> + goto gpio_cleanup;
> + }
> + }
> +
> + ret = of_property_read_u32(np, "default-value", &sdev->value);
> + if (ret)
> + sdev->value = 0;
> +
> + sdev->maxvalue = 1 << sdev->ngpios;
> +
> + sdev->dev_attr.attr.name = "value";
> + sdev->dev_attr.attr.mode = S_IRUGO | S_IWUGO;
> + sdev->dev_attr.show = gpio_7seg_show;
> + sdev->dev_attr.store = gpio_7seg_store;
> +
> + ret = device_create_file(&pdev->dev, &sdev->dev_attr);
> + if (ret)
> + goto gpio_cleanup;
> +
> + gpio_7seg_display_val(sdev, sdev->value);
> +
> + platform_set_drvdata(pdev, sdev);
> + return 0;
> +
> +gpio_cleanup:
> + for (i = 0; i < sdev->ngpios; i++)
> + if (gpio_is_valid(sdev->gpios[i]))
> + gpio_free(sdev->gpios[i]);
> + return ret;
> +}
> +
> +static int gpio_7seg_remove(struct platform_device *pdev)
> +{
> + struct gpio_7seg_dev *sdev;
> + int i;
> +
> + sdev = platform_get_drvdata(pdev);
> +
> + device_remove_file(&pdev->dev, &sdev->dev_attr);
> +
> + for (i = 0; i < sdev->ngpios; i++)
> + if (gpio_is_valid(sdev->gpios[i]))
> + gpio_free(sdev->gpios[i]);
> + return 0;
> +}
> +
> +static const struct of_device_id gpio_7seg_of_match_table[] = {
> + { .compatible = "generic,gpio-7seg" },
> + {},
> +};
> +
> +static struct platform_driver gpio_7seg_driver = {
> + .probe = gpio_7seg_probe,
> + .remove = gpio_7seg_remove,
> + .driver = {
> + .owner = THIS_MODULE,
> + .name = "gpio-7seg",
> + .of_match_table = of_match_ptr(gpio_7seg_of_match_table),
> + },
> +};
> +
> +module_platform_driver(gpio_7seg_driver);
> +
> +MODULE_AUTHOR("Thomas Petazzoni <thomas.petazzoni at free-electrons.com>");
> +MODULE_DESCRIPTION("Simple GPIO-connected 7-segment display driver");
> +MODULE_LICENSE("GPL");
> --
> 1.7.9.5
>
>
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--
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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