Hello all, I understood that the device-tree is for describing hardware and should not contain driver specific information. I have problems drawing this line right now. I made a driver for watchdogs which are pinged by toggling a gpio. Currently the device-tree entry looks like this:
[EMAIL PROTECTED] {
compatible = "gpio-watchdog";
gpios = <&gpio_simple 19 0>;
};
Then, there are two module parameters. One to define the initial state of
the gpio (0 or 1), one to define the length of the pulse when serving
the watchdog (default 1 us). Now my question is:
Is it plausible to say that the module parameters would also fit to the
device-tree as properties? Recently, I tend to say so as otherwise the
description of the watchdog is incomplete. Then again, one might argue
to develop a specific watchdog driver instead of a generic one, and use
something like compatible = "<myvendor>, <mywatchdog>" which would
result in lots of duplicated code per watchdog. So, which way to go? I
am really undecided and would be happy to hear opinions.
For completeness, I'll append the current version of my driver.
All the best,
Wolfram
===
From; Wolfram Sang <[EMAIL PROTECTED]>
Subject; of-driver for external gpio-triggered watchdogs
Still needs tests and review before it can go mainline.
Signed-off-by: Wolfram Sang <[EMAIL PROTECTED]>
---
drivers/watchdog/Kconfig | 8 +
drivers/watchdog/Makefile | 1
drivers/watchdog/of_gpio_wdt.c | 188 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 197 insertions(+)
Index: drivers/watchdog/Kconfig
===================================================================
--- drivers/watchdog/Kconfig.orig
+++ drivers/watchdog/Kconfig
@@ -55,6 +55,14 @@
To compile this driver as a module, choose M here: the
module will be called softdog.
+config OF_GPIO_WDT
+ tristate "OF GPIO watchdog"
+ help
+ This driver handles external watchdogs which are triggered by a gpio.
+
+ To compile this driver as a module, choose M here: the
+ module will be called of_gpio_wdt.
+
# ALPHA Architecture
# ARM Architecture
Index: drivers/watchdog/Makefile
===================================================================
--- drivers/watchdog/Makefile.orig
+++ drivers/watchdog/Makefile
@@ -124,4 +124,5 @@
# XTENSA Architecture
# Architecture Independant
+obj-$(CONFIG_OF_GPIO_WDT) += of_gpio_wdt.o
obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
Index: drivers/watchdog/of_gpio_wdt.c
===================================================================
--- /dev/null
+++ drivers/watchdog/of_gpio_wdt.c
@@ -0,0 +1,188 @@
+/*
+ * of_gpio_wdt.c - driver for gpio-driven watchdogs
+ *
+ * Copyright (C) 2008 Pengutronix e.K.
+ *
+ * Author: Wolfram Sang <[EMAIL PROTECTED]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#define DRIVER_NAME "of-gpio-wdt"
+
+
+static int wdt_gpio;
+
+static int wdt_init_state;
+module_param(wdt_init_state, bool, 0);
+MODULE_PARM_DESC(wdt_init_state,
+ "Initial state of the gpio pin (0/1), default = 0");
+
+static int wdt_toggle_delay = 1;
+module_param(wdt_toggle_delay, int, 0);
+MODULE_PARM_DESC(wdt_toggle_delay,
+ "Delay in us to keep the gpio triggered, default = 1");
+
+static void of_gpio_wdt_ping(void)
+{
+ gpio_set_value(wdt_gpio, wdt_init_state ^ 1);
+ udelay(wdt_toggle_delay);
+ gpio_set_value(wdt_gpio, wdt_init_state);
+}
+
+static ssize_t of_gpio_wdt_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ if (count)
+ of_gpio_wdt_ping();
+ return count;
+}
+
+static int of_gpio_wdt_open(struct inode *inode, struct file *file)
+{
+ of_gpio_wdt_ping();
+ return nonseekable_open(inode, file);
+}
+
+static int of_gpio_wdt_release(struct inode *inode, struct file *file)
+{
+ printk(KERN_CRIT "Unexpected close on watchdog device. "
+ "File is closed, but watchdog is still running!\n");
+ return 0;
+}
+
+static int of_gpio_wdt_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ void __user *argp = (void __user *)arg;
+ static struct watchdog_info ident = {
+ .options = WDIOF_KEEPALIVEPING,
+ .firmware_version = 0,
+ .identity = DRIVER_NAME,
+ };
+
+ switch (cmd) {
+
+ case WDIOC_GETSUPPORT:
+ if (copy_to_user(argp, &ident, sizeof(ident)))
+ return -EFAULT;
+ break;
+
+ case WDIOC_KEEPALIVE:
+ of_gpio_wdt_ping();
+ break;
+
+ case WDIOC_GETTEMP:
+ case WDIOC_GETTIMEOUT:
+ case WDIOC_SETOPTIONS:
+ case WDIOC_SETTIMEOUT:
+ return -EOPNOTSUPP;
+
+ default:
+ return -ENOTTY;
+ }
+
+ return 0;
+}
+
+static const struct file_operations of_gpio_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = of_gpio_wdt_write,
+ .ioctl = of_gpio_wdt_ioctl,
+ .open = of_gpio_wdt_open,
+ .release = of_gpio_wdt_release,
+};
+
+static struct miscdevice of_gpio_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &of_gpio_wdt_fops,
+};
+
+static int __devinit of_gpio_wdt_probe(struct of_device *op,
+ const struct of_device_id *match)
+{
+ int ret;
+
+ wdt_gpio = of_get_gpio(op->node, 0);
+ if (wdt_gpio < 0) {
+ dev_err(&op->dev, "could not determine gpio! (err=%d)\n",
+ wdt_gpio);
+ return wdt_gpio;
+ }
+
+ ret = gpio_request(wdt_gpio, DRIVER_NAME);
+ if (ret) {
+ dev_err(&op->dev, "could not get gpio! (err=%d)\n", ret);
+ return ret;
+ }
+
+ gpio_direction_output(wdt_gpio, wdt_init_state);
+
+ ret = misc_register(&of_gpio_wdt_miscdev);
+ if (ret) {
+ dev_err(&op->dev, "cannot register miscdev on minor=%d "
+ "(err=%d)\n", WATCHDOG_MINOR, ret);
+ gpio_free(wdt_gpio);
+ return -ENODEV;
+ }
+
+ dev_info(&op->dev, "gpio-watchdog driver started using gpio %d.\n",
+ wdt_gpio);
+ return 0;
+}
+
+static int __devexit of_gpio_wdt_remove(struct of_device *op)
+{
+ misc_deregister(&of_gpio_wdt_miscdev);
+ gpio_free(wdt_gpio);
+ return 0;
+}
+
+static struct of_device_id of_gpio_wdt_match[] = {
+ { .compatible = "gpio-watchdog", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, of_gpio_wdt_match);
+
+static struct of_platform_driver of_gpio_wdt_driver = {
+ .owner = THIS_MODULE,
+ .name = DRIVER_NAME,
+ .match_table = of_gpio_wdt_match,
+ .probe = of_gpio_wdt_probe,
+ .remove = __devexit_p(of_gpio_wdt_remove),
+};
+
+static int __init of_gpio_wdt_init(void)
+{
+ return of_register_platform_driver(&of_gpio_wdt_driver);
+}
+
+static void __exit of_gpio_wdt_exit(void)
+{
+ of_unregister_platform_driver(&of_gpio_wdt_driver);
+}
+
+module_init(of_gpio_wdt_init);
+module_exit(of_gpio_wdt_exit);
+
+MODULE_AUTHOR("Wolfram Sang <[EMAIL PROTECTED]>");
+MODULE_DESCRIPTION("Driver for gpio-triggered watchdogs");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--
Dipl.-Ing. Wolfram Sang | http://www.pengutronix.de
Pengutronix - Linux Solutions for Science and Industry
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