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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>
436 lines
9.7 KiB
C
436 lines
9.7 KiB
C
/*
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* Watchdog driver for Atmel AT32AP700X devices
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*
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* Copyright (C) 2005-2006 Atmel Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*
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* Errata: WDT Clear is blocked after WDT Reset
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*
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* A watchdog timer event will, after reset, block writes to the WDT_CLEAR
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* register, preventing the program to clear the next Watchdog Timer Reset.
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*
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* If you still want to use the WDT after a WDT reset a small code can be
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* insterted at the startup checking the AVR32_PM.rcause register for WDT reset
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* and use a GPIO pin to reset the system. This method requires that one of the
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* GPIO pins are available and connected externally to the RESET_N pin. After
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* the GPIO pin has pulled down the reset line the GPIO will be reset and leave
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* the pin tristated with pullup.
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/miscdevice.h>
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#include <linux/fs.h>
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#include <linux/platform_device.h>
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#include <linux/watchdog.h>
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#define TIMEOUT_MIN 1
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#define TIMEOUT_MAX 2
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#define TIMEOUT_DEFAULT TIMEOUT_MAX
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/* module parameters */
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static int timeout = TIMEOUT_DEFAULT;
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module_param(timeout, int, 0);
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MODULE_PARM_DESC(timeout,
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"Timeout value. Limited to be 1 or 2 seconds. (default="
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__MODULE_STRING(TIMEOUT_DEFAULT) ")");
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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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/* Watchdog registers and write/read macro */
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#define WDT_CTRL 0x00
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#define WDT_CTRL_EN 0
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#define WDT_CTRL_PSEL 8
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#define WDT_CTRL_KEY 24
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#define WDT_CLR 0x04
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#define WDT_RCAUSE 0x10
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#define WDT_RCAUSE_POR 0
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#define WDT_RCAUSE_EXT 2
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#define WDT_RCAUSE_WDT 3
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#define WDT_RCAUSE_JTAG 4
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#define WDT_RCAUSE_SERP 5
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#define WDT_BIT(name) (1 << WDT_##name)
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#define WDT_BF(name, value) ((value) << WDT_##name)
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#define wdt_readl(dev, reg) \
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__raw_readl((dev)->regs + WDT_##reg)
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#define wdt_writel(dev, reg, value) \
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__raw_writel((value), (dev)->regs + WDT_##reg)
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struct wdt_at32ap700x {
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void __iomem *regs;
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spinlock_t io_lock;
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int timeout;
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int boot_status;
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unsigned long users;
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struct miscdevice miscdev;
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};
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static struct wdt_at32ap700x *wdt;
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static char expect_release;
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/*
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* Disable the watchdog.
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*/
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static inline void at32_wdt_stop(void)
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{
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unsigned long psel;
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spin_lock(&wdt->io_lock);
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psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
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wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
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wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
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spin_unlock(&wdt->io_lock);
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}
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/*
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* Enable and reset the watchdog.
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*/
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static inline void at32_wdt_start(void)
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{
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/* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
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unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
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spin_lock(&wdt->io_lock);
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wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
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| WDT_BF(CTRL_PSEL, psel)
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| WDT_BF(CTRL_KEY, 0x55));
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wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
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| WDT_BF(CTRL_PSEL, psel)
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| WDT_BF(CTRL_KEY, 0xaa));
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spin_unlock(&wdt->io_lock);
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}
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/*
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* Pat the watchdog timer.
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*/
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static inline void at32_wdt_pat(void)
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{
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spin_lock(&wdt->io_lock);
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wdt_writel(wdt, CLR, 0x42);
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spin_unlock(&wdt->io_lock);
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}
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/*
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* Watchdog device is opened, and watchdog starts running.
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*/
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static int at32_wdt_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(1, &wdt->users))
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return -EBUSY;
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at32_wdt_start();
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return nonseekable_open(inode, file);
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}
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/*
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* Close the watchdog device.
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*/
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static int at32_wdt_close(struct inode *inode, struct file *file)
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{
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if (expect_release == 42) {
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at32_wdt_stop();
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} else {
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dev_dbg(wdt->miscdev.parent,
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"unexpected close, not stopping watchdog!\n");
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at32_wdt_pat();
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}
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clear_bit(1, &wdt->users);
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expect_release = 0;
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return 0;
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}
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/*
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* Change the watchdog time interval.
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*/
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static int at32_wdt_settimeout(int time)
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{
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/*
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* All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
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* 2 ^ 16 allowing up to 2 seconds timeout.
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*/
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if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
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return -EINVAL;
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/*
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* Set new watchdog time. It will be used when at32_wdt_start() is
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* called.
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*/
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wdt->timeout = time;
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return 0;
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}
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/*
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* Get the watchdog status.
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*/
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static int at32_wdt_get_status(void)
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{
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int rcause;
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int status = 0;
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rcause = wdt_readl(wdt, RCAUSE);
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switch (rcause) {
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case WDT_BIT(RCAUSE_EXT):
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status = WDIOF_EXTERN1;
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break;
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case WDT_BIT(RCAUSE_WDT):
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status = WDIOF_CARDRESET;
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break;
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case WDT_BIT(RCAUSE_POR): /* fall through */
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case WDT_BIT(RCAUSE_JTAG): /* fall through */
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case WDT_BIT(RCAUSE_SERP): /* fall through */
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default:
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break;
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}
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return status;
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}
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static const struct watchdog_info at32_wdt_info = {
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.identity = "at32ap700x watchdog",
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.options = WDIOF_SETTIMEOUT |
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WDIOF_KEEPALIVEPING |
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WDIOF_MAGICCLOSE,
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};
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/*
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* Handle commands from user-space.
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*/
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static long at32_wdt_ioctl(struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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int ret = -ENOTTY;
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int time;
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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ret = copy_to_user(argp, &at32_wdt_info,
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sizeof(at32_wdt_info)) ? -EFAULT : 0;
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break;
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case WDIOC_GETSTATUS:
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ret = put_user(0, p);
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break;
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case WDIOC_GETBOOTSTATUS:
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ret = put_user(wdt->boot_status, p);
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break;
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case WDIOC_SETOPTIONS:
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ret = get_user(time, p);
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if (ret)
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break;
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if (time & WDIOS_DISABLECARD)
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at32_wdt_stop();
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if (time & WDIOS_ENABLECARD)
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at32_wdt_start();
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ret = 0;
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break;
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case WDIOC_KEEPALIVE:
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at32_wdt_pat();
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ret = 0;
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break;
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case WDIOC_SETTIMEOUT:
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ret = get_user(time, p);
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if (ret)
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break;
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ret = at32_wdt_settimeout(time);
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if (ret)
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break;
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/* Enable new time value */
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at32_wdt_start();
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/* fall through */
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case WDIOC_GETTIMEOUT:
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ret = put_user(wdt->timeout, p);
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break;
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}
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return ret;
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}
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static ssize_t at32_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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/* See if we got the magic character 'V' and reload the timer */
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if (len) {
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if (!nowayout) {
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size_t i;
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/*
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* note: just in case someone wrote the magic
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* character five months ago...
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*/
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expect_release = 0;
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/*
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* scan to see whether or not we got the magic
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* character
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*/
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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_release = 42;
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}
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}
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/* someone wrote to us, we should pat the watchdog */
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at32_wdt_pat();
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}
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return len;
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}
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static const struct file_operations at32_wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.unlocked_ioctl = at32_wdt_ioctl,
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.open = at32_wdt_open,
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.release = at32_wdt_close,
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.write = at32_wdt_write,
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};
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static int __init at32_wdt_probe(struct platform_device *pdev)
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{
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struct resource *regs;
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int ret;
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if (wdt) {
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dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
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return -EBUSY;
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}
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regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!regs) {
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dev_dbg(&pdev->dev, "missing mmio resource\n");
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return -ENXIO;
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}
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wdt = devm_kzalloc(&pdev->dev, sizeof(struct wdt_at32ap700x),
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GFP_KERNEL);
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if (!wdt) {
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dev_dbg(&pdev->dev, "no memory for wdt structure\n");
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return -ENOMEM;
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}
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wdt->regs = devm_ioremap(&pdev->dev, regs->start, resource_size(regs));
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if (!wdt->regs) {
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ret = -ENOMEM;
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dev_dbg(&pdev->dev, "could not map I/O memory\n");
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goto err_free;
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}
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spin_lock_init(&wdt->io_lock);
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wdt->boot_status = at32_wdt_get_status();
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/* Work-around for watchdog silicon errata. */
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if (wdt->boot_status & WDIOF_CARDRESET) {
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dev_info(&pdev->dev, "CPU must be reset with external "
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"reset or POR due to silicon errata.\n");
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ret = -EIO;
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goto err_free;
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} else {
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wdt->users = 0;
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}
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wdt->miscdev.minor = WATCHDOG_MINOR;
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wdt->miscdev.name = "watchdog";
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wdt->miscdev.fops = &at32_wdt_fops;
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wdt->miscdev.parent = &pdev->dev;
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platform_set_drvdata(pdev, wdt);
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if (at32_wdt_settimeout(timeout)) {
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at32_wdt_settimeout(TIMEOUT_DEFAULT);
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dev_dbg(&pdev->dev,
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"default timeout invalid, set to %d sec.\n",
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TIMEOUT_DEFAULT);
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}
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ret = misc_register(&wdt->miscdev);
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if (ret) {
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dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
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goto err_free;
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}
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dev_info(&pdev->dev,
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"AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
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wdt->regs, wdt->timeout, nowayout);
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return 0;
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err_free:
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wdt = NULL;
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return ret;
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}
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static int __exit at32_wdt_remove(struct platform_device *pdev)
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{
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if (wdt && platform_get_drvdata(pdev) == wdt) {
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/* Stop the timer before we leave */
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if (!nowayout)
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at32_wdt_stop();
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misc_deregister(&wdt->miscdev);
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wdt = NULL;
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}
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return 0;
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}
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static void at32_wdt_shutdown(struct platform_device *pdev)
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{
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at32_wdt_stop();
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}
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#ifdef CONFIG_PM
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static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
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{
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at32_wdt_stop();
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return 0;
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}
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static int at32_wdt_resume(struct platform_device *pdev)
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{
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if (wdt->users)
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at32_wdt_start();
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return 0;
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}
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#else
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#define at32_wdt_suspend NULL
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#define at32_wdt_resume NULL
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#endif
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/* work with hotplug and coldplug */
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MODULE_ALIAS("platform:at32_wdt");
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static struct platform_driver at32_wdt_driver = {
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.remove = __exit_p(at32_wdt_remove),
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.suspend = at32_wdt_suspend,
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.resume = at32_wdt_resume,
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.driver = {
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.name = "at32_wdt",
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.owner = THIS_MODULE,
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},
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.shutdown = at32_wdt_shutdown,
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};
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module_platform_driver_probe(at32_wdt_driver, at32_wdt_probe);
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MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
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MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
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MODULE_LICENSE("GPL");
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