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![Jean Delvare](/assets/img/avatar_default.png)
I just can't find any value in MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) and MODULE_ALIAS_MISCDEV(TEMP_MINOR) statements. Either the device is enumerated and the driver already has a module alias (e.g. PCI, USB etc.) that will get the right driver loaded automatically. Or the device is not enumerated and loading its driver will lead to more or less intrusive hardware poking. Such hardware poking should be limited to a bare minimum, so the user should really decide which drivers should be tried and in what order. Trying them all in arbitrary order can't do any good. On top of that, loading that many drivers at once bloats the kernel log. Also many drivers will stay loaded afterward, bloating the output of "lsmod" and wasting memory. Some modules (cs5535_mfgpt which gets loaded as a dependency) can't even be unloaded! If defining char-major-10-130 is needed then it should happen in user-space. Signed-off-by: Jean Delvare <jdelvare@suse.de> Acked-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Mike Frysinger <vapier.adi@gmail.com> Cc: Wan ZongShun <mcuos.com@gmail.com> Cc: Ben Dooks <ben-linux@fluff.org> Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk> Cc: Jim Cromie <jim.cromie@gmail.com>
334 lines
7.5 KiB
C
334 lines
7.5 KiB
C
/*
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* GE watchdog userspace interface
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*
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* Author: Martyn Welch <martyn.welch@ge.com>
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*
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* Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
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* Author: James Chapman <jchapman@katalix.com>
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*/
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/* TODO:
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* This driver does not provide support for the hardwares capability of sending
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* an interrupt at a programmable threshold.
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*
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* This driver currently can only support 1 watchdog - there are 2 in the
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* hardware that this driver supports. Thus one could be configured as a
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* process-based watchdog (via /dev/watchdog), the second (using the interrupt
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* capabilities) a kernel-based watchdog.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/compiler.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/fs.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_platform.h>
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#include <linux/io.h>
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#include <linux/uaccess.h>
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#include <sysdev/fsl_soc.h>
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/*
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* The watchdog configuration register contains a pair of 2-bit fields,
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* 1. a reload field, bits 27-26, which triggers a reload of
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* the countdown register, and
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* 2. an enable field, bits 25-24, which toggles between
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* enabling and disabling the watchdog timer.
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* Bit 31 is a read-only field which indicates whether the
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* watchdog timer is currently enabled.
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*
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* The low 24 bits contain the timer reload value.
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*/
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#define GEF_WDC_ENABLE_SHIFT 24
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#define GEF_WDC_SERVICE_SHIFT 26
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#define GEF_WDC_ENABLED_SHIFT 31
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#define GEF_WDC_ENABLED_TRUE 1
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#define GEF_WDC_ENABLED_FALSE 0
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/* Flags bits */
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#define GEF_WDOG_FLAG_OPENED 0
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static unsigned long wdt_flags;
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static int wdt_status;
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static void __iomem *gef_wdt_regs;
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static int gef_wdt_timeout;
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static int gef_wdt_count;
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static unsigned int bus_clk;
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static char expect_close;
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static DEFINE_SPINLOCK(gef_wdt_spinlock);
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
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{
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u32 data;
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u32 enabled;
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int ret = 0;
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spin_lock(&gef_wdt_spinlock);
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data = ioread32be(gef_wdt_regs);
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enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
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/* only toggle the requested field if enabled state matches predicate */
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if ((enabled ^ enabled_predicate) == 0) {
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/* We write a 1, then a 2 -- to the appropriate field */
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data = (1 << field_shift) | gef_wdt_count;
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iowrite32be(data, gef_wdt_regs);
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data = (2 << field_shift) | gef_wdt_count;
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iowrite32be(data, gef_wdt_regs);
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ret = 1;
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}
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spin_unlock(&gef_wdt_spinlock);
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return ret;
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}
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static void gef_wdt_service(void)
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{
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gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
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GEF_WDC_SERVICE_SHIFT);
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}
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static void gef_wdt_handler_enable(void)
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{
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if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
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GEF_WDC_ENABLE_SHIFT)) {
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gef_wdt_service();
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pr_notice("watchdog activated\n");
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}
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}
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static void gef_wdt_handler_disable(void)
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{
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if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
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GEF_WDC_ENABLE_SHIFT))
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pr_notice("watchdog deactivated\n");
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}
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static void gef_wdt_set_timeout(unsigned int timeout)
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{
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/* maximum bus cycle count is 0xFFFFFFFF */
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if (timeout > 0xFFFFFFFF / bus_clk)
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timeout = 0xFFFFFFFF / bus_clk;
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/* Register only holds upper 24 bits, bit shifted into lower 24 */
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gef_wdt_count = (timeout * bus_clk) >> 8;
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gef_wdt_timeout = timeout;
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}
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static ssize_t gef_wdt_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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if (len) {
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if (!nowayout) {
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size_t i;
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expect_close = 0;
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for (i = 0; i != len; i++) {
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char c;
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if (get_user(c, data + i))
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return -EFAULT;
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if (c == 'V')
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expect_close = 42;
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}
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}
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gef_wdt_service();
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}
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return len;
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}
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static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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int timeout;
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int options;
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void __user *argp = (void __user *)arg;
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static const struct watchdog_info info = {
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.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
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WDIOF_KEEPALIVEPING,
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.firmware_version = 0,
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.identity = "GE watchdog",
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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if (copy_to_user(argp, &info, sizeof(info)))
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return -EFAULT;
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break;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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if (put_user(wdt_status, (int __user *)argp))
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return -EFAULT;
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wdt_status &= ~WDIOF_KEEPALIVEPING;
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break;
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case WDIOC_SETOPTIONS:
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if (get_user(options, (int __user *)argp))
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return -EFAULT;
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if (options & WDIOS_DISABLECARD)
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gef_wdt_handler_disable();
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if (options & WDIOS_ENABLECARD)
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gef_wdt_handler_enable();
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break;
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case WDIOC_KEEPALIVE:
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gef_wdt_service();
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wdt_status |= WDIOF_KEEPALIVEPING;
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break;
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case WDIOC_SETTIMEOUT:
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if (get_user(timeout, (int __user *)argp))
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return -EFAULT;
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gef_wdt_set_timeout(timeout);
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/* Fall through */
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case WDIOC_GETTIMEOUT:
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if (put_user(gef_wdt_timeout, (int __user *)argp))
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return -EFAULT;
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break;
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default:
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return -ENOTTY;
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}
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return 0;
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}
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static int gef_wdt_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
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return -EBUSY;
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if (nowayout)
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__module_get(THIS_MODULE);
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gef_wdt_handler_enable();
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return nonseekable_open(inode, file);
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}
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static int gef_wdt_release(struct inode *inode, struct file *file)
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{
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if (expect_close == 42)
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gef_wdt_handler_disable();
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else {
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pr_crit("unexpected close, not stopping timer!\n");
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gef_wdt_service();
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}
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expect_close = 0;
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clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
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return 0;
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}
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static const struct file_operations gef_wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = gef_wdt_write,
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.unlocked_ioctl = gef_wdt_ioctl,
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.open = gef_wdt_open,
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.release = gef_wdt_release,
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};
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static struct miscdevice gef_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &gef_wdt_fops,
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};
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static int gef_wdt_probe(struct platform_device *dev)
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{
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int timeout = 10;
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u32 freq;
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bus_clk = 133; /* in MHz */
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freq = fsl_get_sys_freq();
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if (freq != -1)
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bus_clk = freq;
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/* Map devices registers into memory */
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gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
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if (gef_wdt_regs == NULL)
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return -ENOMEM;
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gef_wdt_set_timeout(timeout);
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gef_wdt_handler_disable(); /* in case timer was already running */
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return misc_register(&gef_wdt_miscdev);
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}
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static int gef_wdt_remove(struct platform_device *dev)
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{
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misc_deregister(&gef_wdt_miscdev);
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gef_wdt_handler_disable();
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iounmap(gef_wdt_regs);
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return 0;
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}
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static const struct of_device_id gef_wdt_ids[] = {
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{
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.compatible = "gef,fpga-wdt",
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},
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{},
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};
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static struct platform_driver gef_wdt_driver = {
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.driver = {
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.name = "gef_wdt",
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.owner = THIS_MODULE,
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.of_match_table = gef_wdt_ids,
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},
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.probe = gef_wdt_probe,
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.remove = gef_wdt_remove,
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};
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static int __init gef_wdt_init(void)
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{
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pr_info("GE watchdog driver\n");
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return platform_driver_register(&gef_wdt_driver);
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}
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static void __exit gef_wdt_exit(void)
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{
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platform_driver_unregister(&gef_wdt_driver);
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}
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module_init(gef_wdt_init);
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module_exit(gef_wdt_exit);
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MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
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MODULE_DESCRIPTION("GE watchdog driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:gef_wdt");
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