diff options
Diffstat (limited to 'drivers/watchdog/lantiq_wdt.c')
| -rw-r--r-- | drivers/watchdog/lantiq_wdt.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/drivers/watchdog/lantiq_wdt.c b/drivers/watchdog/lantiq_wdt.c new file mode 100644 index 000000000..582f2fa1b --- /dev/null +++ b/drivers/watchdog/lantiq_wdt.c @@ -0,0 +1,245 @@ +/* + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + * + * Copyright (C) 2010 John Crispin <blogic@openwrt.org> + * Based on EP93xx wdt driver + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/miscdevice.h> +#include <linux/watchdog.h> +#include <linux/of_platform.h> +#include <linux/uaccess.h> +#include <linux/clk.h> +#include <linux/io.h> + +#include <lantiq_soc.h> + +/* + * Section 3.4 of the datasheet + * The password sequence protects the WDT control register from unintended + * write actions, which might cause malfunction of the WDT. + * + * essentially the following two magic passwords need to be written to allow + * IO access to the WDT core + */ +#define LTQ_WDT_PW1 0x00BE0000 +#define LTQ_WDT_PW2 0x00DC0000 + +#define LTQ_WDT_CR 0x0 /* watchdog control register */ +#define LTQ_WDT_SR 0x8 /* watchdog status register */ + +#define LTQ_WDT_SR_EN (0x1 << 31) /* enable bit */ +#define LTQ_WDT_SR_PWD (0x3 << 26) /* turn on power */ +#define LTQ_WDT_SR_CLKDIV (0x3 << 24) /* turn on clock and set */ + /* divider to 0x40000 */ +#define LTQ_WDT_DIVIDER 0x40000 +#define LTQ_MAX_TIMEOUT ((1 << 16) - 1) /* the reload field is 16 bit */ + +static bool nowayout = WATCHDOG_NOWAYOUT; + +static void __iomem *ltq_wdt_membase; +static unsigned long ltq_io_region_clk_rate; + +static unsigned long ltq_wdt_bootstatus; +static unsigned long ltq_wdt_in_use; +static int ltq_wdt_timeout = 30; +static int ltq_wdt_ok_to_close; + +static void +ltq_wdt_enable(void) +{ + unsigned long int timeout = ltq_wdt_timeout * + (ltq_io_region_clk_rate / LTQ_WDT_DIVIDER) + 0x1000; + if (timeout > LTQ_MAX_TIMEOUT) + timeout = LTQ_MAX_TIMEOUT; + + /* write the first password magic */ + ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR); + /* write the second magic plus the configuration and new timeout */ + ltq_w32(LTQ_WDT_SR_EN | LTQ_WDT_SR_PWD | LTQ_WDT_SR_CLKDIV | + LTQ_WDT_PW2 | timeout, ltq_wdt_membase + LTQ_WDT_CR); +} + +static void +ltq_wdt_disable(void) +{ + /* write the first password magic */ + ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR); + /* + * write the second password magic with no config + * this turns the watchdog off + */ + ltq_w32(LTQ_WDT_PW2, ltq_wdt_membase + LTQ_WDT_CR); +} + +static ssize_t +ltq_wdt_write(struct file *file, const char __user *data, + size_t len, loff_t *ppos) +{ + if (len) { + if (!nowayout) { + size_t i; + + ltq_wdt_ok_to_close = 0; + for (i = 0; i != len; i++) { + char c; + + if (get_user(c, data + i)) + return -EFAULT; + if (c == 'V') + ltq_wdt_ok_to_close = 1; + else + ltq_wdt_ok_to_close = 0; + } + } + ltq_wdt_enable(); + } + + return len; +} + +static struct watchdog_info ident = { + .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | + WDIOF_CARDRESET, + .identity = "ltq_wdt", +}; + +static long +ltq_wdt_ioctl(struct file *file, + unsigned int cmd, unsigned long arg) +{ + int ret = -ENOTTY; + + switch (cmd) { + case WDIOC_GETSUPPORT: + ret = copy_to_user((struct watchdog_info __user *)arg, &ident, + sizeof(ident)) ? -EFAULT : 0; + break; + + case WDIOC_GETBOOTSTATUS: + ret = put_user(ltq_wdt_bootstatus, (int __user *)arg); + break; + + case WDIOC_GETSTATUS: + ret = put_user(0, (int __user *)arg); + break; + + case WDIOC_SETTIMEOUT: + ret = get_user(ltq_wdt_timeout, (int __user *)arg); + if (!ret) + ltq_wdt_enable(); + /* intentional drop through */ + case WDIOC_GETTIMEOUT: + ret = put_user(ltq_wdt_timeout, (int __user *)arg); + break; + + case WDIOC_KEEPALIVE: + ltq_wdt_enable(); + ret = 0; + break; + } + return ret; +} + +static int +ltq_wdt_open(struct inode *inode, struct file *file) +{ + if (test_and_set_bit(0, <q_wdt_in_use)) + return -EBUSY; + ltq_wdt_in_use = 1; + ltq_wdt_enable(); + + return nonseekable_open(inode, file); +} + +static int +ltq_wdt_release(struct inode *inode, struct file *file) +{ + if (ltq_wdt_ok_to_close) + ltq_wdt_disable(); + else + pr_err("watchdog closed without warning\n"); + ltq_wdt_ok_to_close = 0; + clear_bit(0, <q_wdt_in_use); + + return 0; +} + +static const struct file_operations ltq_wdt_fops = { + .owner = THIS_MODULE, + .write = ltq_wdt_write, + .unlocked_ioctl = ltq_wdt_ioctl, + .open = ltq_wdt_open, + .release = ltq_wdt_release, + .llseek = no_llseek, +}; + +static struct miscdevice ltq_wdt_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "watchdog", + .fops = <q_wdt_fops, +}; + +static int +ltq_wdt_probe(struct platform_device *pdev) +{ + struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + struct clk *clk; + + ltq_wdt_membase = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(ltq_wdt_membase)) + return PTR_ERR(ltq_wdt_membase); + + /* we do not need to enable the clock as it is always running */ + clk = clk_get_io(); + if (IS_ERR(clk)) { + dev_err(&pdev->dev, "Failed to get clock\n"); + return -ENOENT; + } + ltq_io_region_clk_rate = clk_get_rate(clk); + clk_put(clk); + + /* find out if the watchdog caused the last reboot */ + if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST) + ltq_wdt_bootstatus = WDIOF_CARDRESET; + + dev_info(&pdev->dev, "Init done\n"); + return misc_register(<q_wdt_miscdev); +} + +static int +ltq_wdt_remove(struct platform_device *pdev) +{ + misc_deregister(<q_wdt_miscdev); + + return 0; +} + +static const struct of_device_id ltq_wdt_match[] = { + { .compatible = "lantiq,wdt" }, + {}, +}; +MODULE_DEVICE_TABLE(of, ltq_wdt_match); + +static struct platform_driver ltq_wdt_driver = { + .probe = ltq_wdt_probe, + .remove = ltq_wdt_remove, + .driver = { + .name = "wdt", + .of_match_table = ltq_wdt_match, + }, +}; + +module_platform_driver(ltq_wdt_driver); + +module_param(nowayout, bool, 0); +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"); +MODULE_AUTHOR("John Crispin <blogic@openwrt.org>"); +MODULE_DESCRIPTION("Lantiq SoC Watchdog"); +MODULE_LICENSE("GPL"); |