--- /dev/null
+/*
+ * GE watchdog userspace interface
+ *
+ * Author: Martyn Welch <martyn.welch@ge.com>
+ *
+ * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
+ *
+ * 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; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
+ * Author: James Chapman <jchapman@katalix.com>
+ */
+
+/* TODO:
+ * This driver does not provide support for the hardwares capability of sending
+ * an interrupt at a programmable threshold.
+ *
+ * This driver currently can only support 1 watchdog - there are 2 in the
+ * hardware that this driver supports. Thus one could be configured as a
+ * process-based watchdog (via /dev/watchdog), the second (using the interrupt
+ * capabilities) a kernel-based watchdog.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/compiler.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#include <sysdev/fsl_soc.h>
+
+/*
+ * The watchdog configuration register contains a pair of 2-bit fields,
+ * 1. a reload field, bits 27-26, which triggers a reload of
+ * the countdown register, and
+ * 2. an enable field, bits 25-24, which toggles between
+ * enabling and disabling the watchdog timer.
+ * Bit 31 is a read-only field which indicates whether the
+ * watchdog timer is currently enabled.
+ *
+ * The low 24 bits contain the timer reload value.
+ */
+#define GEF_WDC_ENABLE_SHIFT 24
+#define GEF_WDC_SERVICE_SHIFT 26
+#define GEF_WDC_ENABLED_SHIFT 31
+
+#define GEF_WDC_ENABLED_TRUE 1
+#define GEF_WDC_ENABLED_FALSE 0
+
+/* Flags bits */
+#define GEF_WDOG_FLAG_OPENED 0
+
+static unsigned long wdt_flags;
+static int wdt_status;
+static void __iomem *gef_wdt_regs;
+static int gef_wdt_timeout;
+static int gef_wdt_count;
+static unsigned int bus_clk;
+static char expect_close;
+static DEFINE_SPINLOCK(gef_wdt_spinlock);
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+
+static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
+{
+ u32 data;
+ u32 enabled;
+ int ret = 0;
+
+ spin_lock(&gef_wdt_spinlock);
+ data = ioread32be(gef_wdt_regs);
+ enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
+
+ /* only toggle the requested field if enabled state matches predicate */
+ if ((enabled ^ enabled_predicate) == 0) {
+ /* We write a 1, then a 2 -- to the appropriate field */
+ data = (1 << field_shift) | gef_wdt_count;
+ iowrite32be(data, gef_wdt_regs);
+
+ data = (2 << field_shift) | gef_wdt_count;
+ iowrite32be(data, gef_wdt_regs);
+ ret = 1;
+ }
+ spin_unlock(&gef_wdt_spinlock);
+
+ return ret;
+}
+
+static void gef_wdt_service(void)
+{
+ gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
+ GEF_WDC_SERVICE_SHIFT);
+}
+
+static void gef_wdt_handler_enable(void)
+{
+ if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
+ GEF_WDC_ENABLE_SHIFT)) {
+ gef_wdt_service();
+ pr_notice("watchdog activated\n");
+ }
+}
+
+static void gef_wdt_handler_disable(void)
+{
+ if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
+ GEF_WDC_ENABLE_SHIFT))
+ pr_notice("watchdog deactivated\n");
+}
+
+static void gef_wdt_set_timeout(unsigned int timeout)
+{
+ /* maximum bus cycle count is 0xFFFFFFFF */
+ if (timeout > 0xFFFFFFFF / bus_clk)
+ timeout = 0xFFFFFFFF / bus_clk;
+
+ /* Register only holds upper 24 bits, bit shifted into lower 24 */
+ gef_wdt_count = (timeout * bus_clk) >> 8;
+ gef_wdt_timeout = timeout;
+}
+
+
+static ssize_t gef_wdt_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ if (len) {
+ if (!nowayout) {
+ size_t i;
+
+ expect_close = 0;
+
+ for (i = 0; i != len; i++) {
+ char c;
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V')
+ expect_close = 42;
+ }
+ }
+ gef_wdt_service();
+ }
+
+ return len;
+}
+
+static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ int timeout;
+ int options;
+ void __user *argp = (void __user *)arg;
+ static const struct watchdog_info info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
+ WDIOF_KEEPALIVEPING,
+ .firmware_version = 0,
+ .identity = "GE watchdog",
+ };
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ if (copy_to_user(argp, &info, sizeof(info)))
+ return -EFAULT;
+ break;
+
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ if (put_user(wdt_status, (int __user *)argp))
+ return -EFAULT;
+ wdt_status &= ~WDIOF_KEEPALIVEPING;
+ break;
+
+ case WDIOC_SETOPTIONS:
+ if (get_user(options, (int __user *)argp))
+ return -EFAULT;
+
+ if (options & WDIOS_DISABLECARD)
+ gef_wdt_handler_disable();
+
+ if (options & WDIOS_ENABLECARD)
+ gef_wdt_handler_enable();
+ break;
+
+ case WDIOC_KEEPALIVE:
+ gef_wdt_service();
+ wdt_status |= WDIOF_KEEPALIVEPING;
+ break;
+
+ case WDIOC_SETTIMEOUT:
+ if (get_user(timeout, (int __user *)argp))
+ return -EFAULT;
+ gef_wdt_set_timeout(timeout);
+ /* Fall through */
+
+ case WDIOC_GETTIMEOUT:
+ if (put_user(gef_wdt_timeout, (int __user *)argp))
+ return -EFAULT;
+ break;
+
+ default:
+ return -ENOTTY;
+ }
+
+ return 0;
+}
+
+static int gef_wdt_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
+ return -EBUSY;
+
+ if (nowayout)
+ __module_get(THIS_MODULE);
+
+ gef_wdt_handler_enable();
+
+ return nonseekable_open(inode, file);
+}
+
+static int gef_wdt_release(struct inode *inode, struct file *file)
+{
+ if (expect_close == 42)
+ gef_wdt_handler_disable();
+ else {
+ pr_crit("unexpected close, not stopping timer!\n");
+ gef_wdt_service();
+ }
+ expect_close = 0;
+
+ clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
+
+ return 0;
+}
+
+static const struct file_operations gef_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = gef_wdt_write,
+ .unlocked_ioctl = gef_wdt_ioctl,
+ .open = gef_wdt_open,
+ .release = gef_wdt_release,
+};
+
+static struct miscdevice gef_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &gef_wdt_fops,
+};
+
+
+static int gef_wdt_probe(struct platform_device *dev)
+{
+ int timeout = 10;
+ u32 freq;
+
+ bus_clk = 133; /* in MHz */
+
+ freq = fsl_get_sys_freq();
+ if (freq != -1)
+ bus_clk = freq;
+
+ /* Map devices registers into memory */
+ gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
+ if (gef_wdt_regs == NULL)
+ return -ENOMEM;
+
+ gef_wdt_set_timeout(timeout);
+
+ gef_wdt_handler_disable(); /* in case timer was already running */
+
+ return misc_register(&gef_wdt_miscdev);
+}
+
+static int gef_wdt_remove(struct platform_device *dev)
+{
+ misc_deregister(&gef_wdt_miscdev);
+
+ gef_wdt_handler_disable();
+
+ iounmap(gef_wdt_regs);
+
+ return 0;
+}
+
+static const struct of_device_id gef_wdt_ids[] = {
+ {
+ .compatible = "gef,fpga-wdt",
+ },
+ {},
+};
+
+static struct platform_driver gef_wdt_driver = {
+ .driver = {
+ .name = "gef_wdt",
+ .of_match_table = gef_wdt_ids,
+ },
+ .probe = gef_wdt_probe,
+ .remove = gef_wdt_remove,
+};
+
+static int __init gef_wdt_init(void)
+{
+ pr_info("GE watchdog driver\n");
+ return platform_driver_register(&gef_wdt_driver);
+}
+
+static void __exit gef_wdt_exit(void)
+{
+ platform_driver_unregister(&gef_wdt_driver);
+}
+
+module_init(gef_wdt_init);
+module_exit(gef_wdt_exit);
+
+MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
+MODULE_DESCRIPTION("GE watchdog driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gef_wdt");
Code Review / kvmfornfv.git / blobdiff