[PATCH 3.9 1/3] misc: new driver for GPIO-connected 7-segment displays
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Tue Jan 8 03:42:06 EST 2013
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>;
+};
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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