[PATCH linux v2 2/3] drivers: misc: Platform driver for seven segment display
Jaghathiswari Rankappagounder Natarajan
jaghu at google.com
Tue Oct 18 04:10:47 AEDT 2016
Platform driver provides an API for displaying on a 7-segment display,
and implements the required bit-banging.
Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu at google.com>
---
.../bindings/misc/seven_segment_disp.txt | 23 +++
drivers/misc/Kconfig | 7 +
drivers/misc/Makefile | 1 +
drivers/misc/seven_seg_gpio.c | 202 +++++++++++++++++++++
4 files changed, 233 insertions(+)
create mode 100644 Documentation/devicetree/bindings/misc/seven_segment_disp.txt
create mode 100644 drivers/misc/seven_seg_gpio.c
diff --git a/Documentation/devicetree/bindings/misc/seven_segment_disp.txt b/Documentation/devicetree/bindings/misc/seven_segment_disp.txt
new file mode 100644
index 0000000..9c01b97
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/seven_segment_disp.txt
@@ -0,0 +1,23 @@
+Seven segment display support connected to GPIO lines
+
+Required properties:
+- compatible : should be "seven-seg-gpio-dev".
+- clock-gpios : Should specify the GPIO pin connected to the Clock line on the hardware.
+- data-gpios : Should specify the GPIO pin connected to Data line on the hardware.
+- clear-gpios : Should specify the GPIO pin connected to Clear line on the hardware.
+
+Optional properties:
+- refresh-interval-ms : The interval at which to refresh the display.
+ If this property is not present, the default value is 1000.
+
+Examples:
+
+#include <dt-bindings/gpio/gpio.h>
+
+seven-seg-disp {
+ compatible = "seven-seg-gpio-dev";
+ refresh-interval-ms = "1000";
+ clock-gpios = <&gpio 0 GPIO_ACTIVE_LOW>;
+ data-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>;
+ clear-gpios = <&gpio 2 GPIO_ACTIVE_HIGH>;
+};
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index cf07817..7adb9e3 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -814,6 +814,13 @@ config ASPEED_BT_IPMI_HOST
help
Support for the Aspeed BT ipmi host.
+config SEVEN_SEGMENT_GPIO
+ tristate "Platform driver to update seven segment display"
+ depends on SEVEN_SEGMENT_DISPLAY
+ help
+ Support to periodically update display on two seven segment displays.
+ The hardware assumed is 74HC164 wired to two seven segment displays.
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 718dc2b..71e364d 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -59,3 +59,4 @@ obj-$(CONFIG_CXL_BASE) += cxl/
obj-$(CONFIG_PANEL) += panel.o
obj-$(CONFIG_SEVEN_SEGMENT_DISPLAY) += seven_seg_disp.o
obj-$(CONFIG_ASPEED_BT_IPMI_HOST) += bt-host.o
+obj-$(CONFIG_SEVEN_SEGMENT_GPIO) += seven_seg_gpio.o
diff --git a/drivers/misc/seven_seg_gpio.c b/drivers/misc/seven_seg_gpio.c
new file mode 100644
index 0000000..f64f280
--- /dev/null
+++ b/drivers/misc/seven_seg_gpio.c
@@ -0,0 +1,202 @@
+/*
+ * Platform driver to periodically update two 7-segment LED
+ * * displays. Hardware assumed is 74HC164 shift register wired to two
+ * * 7-segment LED displays.
+ * *
+ * * Copyright (C) 2016 Google, Inc
+ * *
+ * * This program is free software; you can redistribute it and/or modify
+ * * it under the terms of the GNU General Public License version 2 as
+ * * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+#include <linux/sizes.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/uaccess.h>
+#include <linux/mutex.h>
+#include <linux/of_platform.h>
+#include <linux/gpio/consumer.h>
+
+#include "seven_seg_gen.h"
+
+#define DELAY_INTVL_US 1
+
+#define CLOCK_GPIO_NAME "clock"
+#define DATA_GPIO_NAME "data"
+#define CLEAR_GPIO_NAME "clear"
+
+struct seven_seg_gpio_info {
+ u8 disp_data_valid;
+ u16 curr_disp_value;
+ u16 refresh_interval;
+ struct mutex mutex;
+ struct timer_list update_timer;
+ struct gpio_desc *clock_gpio;
+ struct gpio_desc *data_gpio;
+ struct gpio_desc *clear_gpio;
+};
+
+static void update_seven_seg_gpio_data(struct device *dev, u16 data)
+{
+ struct platform_device *pdev;
+ struct seven_seg_gpio_info *gpio_info;
+
+ pdev = container_of(dev, struct platform_device, dev);
+ if (pdev == NULL) {
+ pr_err("invalid NULL platform_device\n");
+ return;
+ }
+
+ gpio_info = platform_get_drvdata(pdev);
+ if (gpio_info == NULL) {
+ pr_err("invalid NULL vpu_subdev_data\n");
+ return;
+ }
+
+ mutex_lock(&gpio_info->mutex);
+ gpio_info->curr_disp_value = data;
+ gpio_info->disp_data_valid = 1;
+ mutex_unlock(&gpio_info->mutex);
+
+}
+
+static void send_seven_seg_gpio_data(u16 disp_data,
+ struct seven_seg_gpio_info *gpio_info)
+{
+ int i;
+
+ gpiod_set_value(gpio_info->clear_gpio, 0);
+ udelay(DELAY_INTVL_US);
+ gpiod_set_value(gpio_info->clear_gpio, 1);
+ udelay(DELAY_INTVL_US);
+
+ for (i = 0; i < 16; i++) {
+ if (disp_data & 0x01) {
+ gpiod_set_value(gpio_info->data_gpio, 1);
+ } else {
+ gpiod_set_value(gpio_info->data_gpio, 0);
+ }
+ udelay(DELAY_INTVL_US);
+
+ gpiod_set_value(gpio_info->clock_gpio, 0);
+ udelay(DELAY_INTVL_US);
+ gpiod_set_value(gpio_info->clock_gpio, 1);
+ udelay(DELAY_INTVL_US);
+
+ disp_data >>= 1;
+ }
+}
+
+static void disp_refresh_timer_handler(unsigned long data)
+{
+ u8 valid = 0;
+ u16 disp_data;
+ struct seven_seg_gpio_info *gpio_info =
+ (struct seven_seg_gpio_info *)data;
+ mutex_lock(&gpio_info->mutex);
+ if (gpio_info->disp_data_valid) {
+ valid = 1;
+ disp_data = gpio_info->curr_disp_value;
+ }
+ mutex_unlock(&gpio_info->mutex);
+
+ if (valid)
+ send_seven_seg_gpio_data(disp_data, gpio_info);
+ mod_timer(&gpio_info->update_timer,
+ jiffies + msecs_to_jiffies(gpio_info->refresh_interval);
+}
+
+static const struct of_device_id of_seven_seg_gpio_match[] = {
+ { .compatible = "seven-seg-gpio-dev" },
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, of_seven_seg_gpio_match);
+
+static int seven_seg_gpio_probe(struct platform_device *pdev)
+{
+ u16 interval;
+ int result;
+ struct seven_seg_gpio_info *gpio_info;
+ struct device *dev = &pdev->dev;
+ struct seven_seg_disp_dev *disp_dev;
+
+ gpio_info = devm_kzalloc(dev,
+ sizeof(struct seven_seg_gpio_info),
+ GFP_KERNEL);
+ if (gpio_info == NULL)
+ return -ENOMEM;
+
+ /* Requesting the clock gpio */
+ gpio_info->clock_gpio = devm_gpiod_get(dev, CLOCK_GPIO_NAME,
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(gpio_info->clock_gpio))
+ return PTR_ERR(gpio_info->clock_gpio);
+
+ /* Requesting the data gpio */
+ gpio_info->data_gpio = devm_gpiod_get(dev, DATA_GPIO_NAME,
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(gpio_info->data_gpio))
+ return PTR_ERR(gpio_info->data_gpio);
+
+ /* Requesting the clear gpio */
+ gpio_info->clear_gpio = devm_gpiod_get(dev, CLEAR_GPIO_NAME,
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(gpio_info->clear_gpio))
+ return PTR_ERR(gpio_info->clear_gpio);
+
+ result = of_property_read_u16(pdev->dev.of_node,
+ "refresh-interval-ms", &interval);
+ gpio_info->refresh_interval = result ? DEFAULT_REFRESH_INTERVAL :
+ interval;
+
+ /* Start timer to update seven segment display every second */
+ setup_timer(&gpio_info->update_timer, disp_refresh_timer_handler,
+ (unsigned long)gpio_info);
+ result = mod_timer(&gpio_info->update_timer,
+ jiffies +
+ msecs_to_jiffies(gpio_info->refresh_interval));
+ if (result)
+ return result;
+
+ mutex_init(&gpio_info->mutex);
+
+ platform_set_drvdata(pdev, gpio_info);
+
+ disp_dev = devm_kzalloc(dev, sizeof(struct seven_seg_disp_dev),
+ GFP_KERNEL);
+ setup_cdev(*dev, disp_dev, &update_seven_seg_gpio_data);
+
+ return 0;
+}
+
+static int seven_seg_gpio_remove(struct platform_device *pdev)
+{
+ struct seven_seg_gpio_info *gpio_info = platform_get_drvdata(pdev);
+ struct seven_seg_disp_dev *disp_dev =
+ container_of(&pdev->dev, struct seven_seg_disp_dev, parent);
+ rem_cdev(disp_dev);
+ del_timer_sync(&gpio_info->update_timer);
+ platform_set_drvdata(pdev, NULL);
+ return 0;
+}
+
+static struct platform_driver seven_seg_gpio_driver = {
+ .probe = seven_seg_gpio_probe,
+ .remove = seven_seg_gpio_remove,
+ .driver = {
+ .name = "seven-seg-gpio",
+ .of_match_table = of_seven_seg_gpio_match,
+ },
+};
+
+module_platform_driver(seven_seg_gpio_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jaghathiswari Rankappagounder Natarajan <jaghu at google.com>");
+MODULE_DESCRIPTION("Seven segment display driver using GPIO config");
--
2.8.0.rc3.226.g39d4020
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