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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>
326 lines
7.7 KiB
C
326 lines
7.7 KiB
C
/*
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* mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
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*
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* Author: James Chapman <jchapman@katalix.com>
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*
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* Platform-specific setup code should configure the dog to generate
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* interrupt or reset as required. This code only enables/disables
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* and services the watchdog.
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*
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* Derived from mpc8xx_wdt.c, with the following copyright.
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*
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* 2002 (c) Florian Schirmer <jolt@tuxbox.org> This file is licensed under
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* the terms of the GNU General Public License version 2. This program
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* is licensed "as is" without any warranty of any kind, whether express
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* or implied.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/watchdog.h>
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#include <linux/platform_device.h>
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#include <linux/mv643xx.h>
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#define MV64x60_WDT_WDC_OFFSET 0
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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 MV64x60_WDC_ENABLE_SHIFT 24
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#define MV64x60_WDC_SERVICE_SHIFT 26
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#define MV64x60_WDC_ENABLED_SHIFT 31
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#define MV64x60_WDC_ENABLED_TRUE 1
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#define MV64x60_WDC_ENABLED_FALSE 0
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/* Flags bits */
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#define MV64x60_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 *mv64x60_wdt_regs;
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static int mv64x60_wdt_timeout;
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static int mv64x60_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(mv64x60_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,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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static int mv64x60_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(&mv64x60_wdt_spinlock);
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data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
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enabled = (data >> MV64x60_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) | mv64x60_wdt_count;
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writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
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data = (2 << field_shift) | mv64x60_wdt_count;
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writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
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ret = 1;
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}
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spin_unlock(&mv64x60_wdt_spinlock);
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return ret;
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}
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static void mv64x60_wdt_service(void)
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{
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mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
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MV64x60_WDC_SERVICE_SHIFT);
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}
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static void mv64x60_wdt_handler_enable(void)
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{
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if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
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MV64x60_WDC_ENABLE_SHIFT)) {
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mv64x60_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 mv64x60_wdt_handler_disable(void)
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{
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if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
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MV64x60_WDC_ENABLE_SHIFT))
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pr_notice("watchdog deactivated\n");
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}
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static void mv64x60_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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mv64x60_wdt_count = timeout * bus_clk >> 8;
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mv64x60_wdt_timeout = timeout;
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}
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static int mv64x60_wdt_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(MV64x60_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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mv64x60_wdt_handler_enable();
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return nonseekable_open(inode, file);
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}
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static int mv64x60_wdt_release(struct inode *inode, struct file *file)
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{
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if (expect_close == 42)
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mv64x60_wdt_handler_disable();
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else {
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pr_crit("unexpected close, not stopping timer!\n");
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mv64x60_wdt_service();
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}
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expect_close = 0;
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clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
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return 0;
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}
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static ssize_t mv64x60_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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mv64x60_wdt_service();
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}
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return len;
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}
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static long mv64x60_wdt_ioctl(struct file *file,
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unsigned int cmd, 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 |
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WDIOF_MAGICCLOSE |
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WDIOF_KEEPALIVEPING,
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.firmware_version = 0,
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.identity = "MV64x60 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_GETTEMP:
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return -EOPNOTSUPP;
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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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mv64x60_wdt_handler_disable();
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if (options & WDIOS_ENABLECARD)
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mv64x60_wdt_handler_enable();
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break;
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case WDIOC_KEEPALIVE:
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mv64x60_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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mv64x60_wdt_set_timeout(timeout);
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/* Fall through */
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case WDIOC_GETTIMEOUT:
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if (put_user(mv64x60_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 const struct file_operations mv64x60_wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = mv64x60_wdt_write,
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.unlocked_ioctl = mv64x60_wdt_ioctl,
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.open = mv64x60_wdt_open,
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.release = mv64x60_wdt_release,
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};
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static struct miscdevice mv64x60_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &mv64x60_wdt_fops,
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};
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static int mv64x60_wdt_probe(struct platform_device *dev)
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{
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struct mv64x60_wdt_pdata *pdata = dev_get_platdata(&dev->dev);
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struct resource *r;
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int timeout = 10;
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bus_clk = 133; /* in MHz */
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if (pdata) {
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timeout = pdata->timeout;
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bus_clk = pdata->bus_clk;
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}
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/* Since bus_clk is truncated MHz, actual frequency could be
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* up to 1MHz higher. Round up, since it's better to time out
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* too late than too soon.
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*/
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bus_clk++;
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bus_clk *= 1000000; /* convert to Hz */
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r = platform_get_resource(dev, IORESOURCE_MEM, 0);
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if (!r)
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return -ENODEV;
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mv64x60_wdt_regs = devm_ioremap(&dev->dev, r->start, resource_size(r));
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if (mv64x60_wdt_regs == NULL)
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return -ENOMEM;
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mv64x60_wdt_set_timeout(timeout);
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mv64x60_wdt_handler_disable(); /* in case timer was already running */
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return misc_register(&mv64x60_wdt_miscdev);
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}
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static int mv64x60_wdt_remove(struct platform_device *dev)
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{
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misc_deregister(&mv64x60_wdt_miscdev);
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mv64x60_wdt_handler_disable();
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return 0;
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}
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static struct platform_driver mv64x60_wdt_driver = {
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.probe = mv64x60_wdt_probe,
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.remove = mv64x60_wdt_remove,
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.driver = {
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.owner = THIS_MODULE,
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.name = MV64x60_WDT_NAME,
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},
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};
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static int __init mv64x60_wdt_init(void)
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{
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pr_info("MV64x60 watchdog driver\n");
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return platform_driver_register(&mv64x60_wdt_driver);
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}
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static void __exit mv64x60_wdt_exit(void)
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{
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platform_driver_unregister(&mv64x60_wdt_driver);
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}
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module_init(mv64x60_wdt_init);
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module_exit(mv64x60_wdt_exit);
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MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
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MODULE_DESCRIPTION("MV64x60 watchdog driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:" MV64x60_WDT_NAME);
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