[PATCH linux v1 3/4] drivers: misc: Platform driver for seven segment display support

[Jaghathiswari Rankappagounder Natarajan]

Platform device driver which provides an API for displaying on two
7-segment displays, and implements the required bit-banging.
The hardware assumed is 74HC164 wired to two 7-segment displays.

Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@xxxxxxxxxx>
---
 drivers/misc/Kconfig          |   8 ++
 drivers/misc/Makefile         |   1 +
 drivers/misc/seven_seg_gpio.c | 206 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 215 insertions(+)
 create mode 100644 drivers/misc/seven_seg_gpio.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index a21aec1..6508108 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -812,6 +812,14 @@ config PANEL_BOOT_MESSAGE
 	  An empty message will only clear the display at driver init time. Any other
 	  printf()-formatted message is valid with newline and escape codes.

+config SEVEN_SEGMENT_GPIO
+	tristate "Platform driver to update seven segment display"
+	depends on SEVEN_SEGMENT_DISPLAY
+	help
+	  Platform device driver which provides an API for displaying on two
+	  7-segment displays, and implements the required bit-banging.
+	  The hardware assumed is 74HC164 wired to two 7-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 c2defbd..d9c0d20 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -58,3 +58,4 @@ obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_SEVEN_SEGMENT_DISPLAY)	+= seven_seg_disp.o
 obj-$(CONFIG_PANEL)             += panel.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..3dcb903
--- /dev/null
+++ b/drivers/misc/seven_seg_gpio.c
@@ -0,0 +1,206 @@
+/*
+ * 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 or later 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_disp.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 {
+	u16 curr_disp_value;
+	u16 refresh_interval;
+	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 gpio_info\n");
+		return;
+	}
+
+	gpio_info->curr_disp_value = data;
+}
+
+static void clear_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 gpio_info\n");
+		return;
+	}
+
+	gpio_info->curr_disp_value = 0;
+}
+
+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)
+{
+	u16 disp_data;
+	struct seven_seg_gpio_info *gpio_info =
+		(struct seven_seg_gpio_info *)data;
+	disp_data = gpio_info->curr_disp_value;
+
+	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_MS :
+		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;
+
+	gpio_info->curr_disp_value = 0;
+
+	platform_set_drvdata(pdev, gpio_info);
+
+	disp_dev = devm_kzalloc(dev, sizeof(struct seven_seg_disp_dev),
+				GFP_KERNEL);
+	disp_dev->parent = *dev;
+	seven_seg_setup_cdev(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);
+	seven_seg_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@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Seven segment display driver using GPIO config");
--
2.8.0.rc3.226.g39d4020