| /* |
| * drivers/char/watchdog/sp805-wdt.c |
| * |
| * Watchdog driver for ARM SP805 watchdog module |
| * |
| * Copyright (C) 2010 ST Microelectronics |
| * Viresh Kumar<viresh.kumar@st.com> |
| * |
| * This file is licensed under the terms of the GNU General Public |
| * License version 2 or later. This program is licensed "as is" without any |
| * warranty of any kind, whether express or implied. |
| */ |
| |
| #include <linux/device.h> |
| #include <linux/resource.h> |
| #include <linux/amba/bus.h> |
| #include <linux/bitops.h> |
| #include <linux/clk.h> |
| #include <linux/fs.h> |
| #include <linux/init.h> |
| #include <linux/io.h> |
| #include <linux/ioport.h> |
| #include <linux/kernel.h> |
| #include <linux/math64.h> |
| #include <linux/miscdevice.h> |
| #include <linux/module.h> |
| #include <linux/moduleparam.h> |
| #include <linux/pm.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/types.h> |
| #include <linux/uaccess.h> |
| #include <linux/watchdog.h> |
| |
| /* default timeout in seconds */ |
| #define DEFAULT_TIMEOUT 60 |
| |
| #define MODULE_NAME "sp805-wdt" |
| |
| /* watchdog register offsets and masks */ |
| #define WDTLOAD 0x000 |
| #define LOAD_MIN 0x00000001 |
| #define LOAD_MAX 0xFFFFFFFF |
| #define WDTVALUE 0x004 |
| #define WDTCONTROL 0x008 |
| /* control register masks */ |
| #define INT_ENABLE (1 << 0) |
| #define RESET_ENABLE (1 << 1) |
| #define WDTINTCLR 0x00C |
| #define WDTRIS 0x010 |
| #define WDTMIS 0x014 |
| #define INT_MASK (1 << 0) |
| #define WDTLOCK 0xC00 |
| #define UNLOCK 0x1ACCE551 |
| #define LOCK 0x00000001 |
| |
| /** |
| * struct sp805_wdt: sp805 wdt device structure |
| * |
| * lock: spin lock protecting dev structure and io access |
| * base: base address of wdt |
| * clk: clock structure of wdt |
| * dev: amba device structure of wdt |
| * status: current status of wdt |
| * load_val: load value to be set for current timeout |
| * timeout: current programmed timeout |
| */ |
| struct sp805_wdt { |
| spinlock_t lock; |
| void __iomem *base; |
| struct clk *clk; |
| struct amba_device *adev; |
| unsigned long status; |
| #define WDT_BUSY 0 |
| #define WDT_CAN_BE_CLOSED 1 |
| unsigned int load_val; |
| unsigned int timeout; |
| }; |
| |
| /* local variables */ |
| static struct sp805_wdt *wdt; |
| static bool nowayout = WATCHDOG_NOWAYOUT; |
| |
| /* This routine finds load value that will reset system in required timout */ |
| static void wdt_setload(unsigned int timeout) |
| { |
| u64 load, rate; |
| |
| rate = clk_get_rate(wdt->clk); |
| |
| /* |
| * sp805 runs counter with given value twice, after the end of first |
| * counter it gives an interrupt and then starts counter again. If |
| * interrupt already occurred then it resets the system. This is why |
| * load is half of what should be required. |
| */ |
| load = div_u64(rate, 2) * timeout - 1; |
| |
| load = (load > LOAD_MAX) ? LOAD_MAX : load; |
| load = (load < LOAD_MIN) ? LOAD_MIN : load; |
| |
| spin_lock(&wdt->lock); |
| wdt->load_val = load; |
| /* roundup timeout to closest positive integer value */ |
| wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate); |
| spin_unlock(&wdt->lock); |
| } |
| |
| /* returns number of seconds left for reset to occur */ |
| static u32 wdt_timeleft(void) |
| { |
| u64 load, rate; |
| |
| rate = clk_get_rate(wdt->clk); |
| |
| spin_lock(&wdt->lock); |
| load = readl(wdt->base + WDTVALUE); |
| |
| /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */ |
| if (!(readl(wdt->base + WDTRIS) & INT_MASK)) |
| load += wdt->load_val + 1; |
| spin_unlock(&wdt->lock); |
| |
| return div_u64(load, rate); |
| } |
| |
| /* enables watchdog timers reset */ |
| static void wdt_enable(void) |
| { |
| spin_lock(&wdt->lock); |
| |
| writel(UNLOCK, wdt->base + WDTLOCK); |
| writel(wdt->load_val, wdt->base + WDTLOAD); |
| writel(INT_MASK, wdt->base + WDTINTCLR); |
| writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL); |
| writel(LOCK, wdt->base + WDTLOCK); |
| |
| /* Flush posted writes. */ |
| readl(wdt->base + WDTLOCK); |
| spin_unlock(&wdt->lock); |
| } |
| |
| /* disables watchdog timers reset */ |
| static void wdt_disable(void) |
| { |
| spin_lock(&wdt->lock); |
| |
| writel(UNLOCK, wdt->base + WDTLOCK); |
| writel(0, wdt->base + WDTCONTROL); |
| writel(LOCK, wdt->base + WDTLOCK); |
| |
| /* Flush posted writes. */ |
| readl(wdt->base + WDTLOCK); |
| spin_unlock(&wdt->lock); |
| } |
| |
| static ssize_t sp805_wdt_write(struct file *file, const char *data, |
| size_t len, loff_t *ppos) |
| { |
| if (len) { |
| if (!nowayout) { |
| size_t i; |
| |
| clear_bit(WDT_CAN_BE_CLOSED, &wdt->status); |
| |
| for (i = 0; i != len; i++) { |
| char c; |
| |
| if (get_user(c, data + i)) |
| return -EFAULT; |
| /* Check for Magic Close character */ |
| if (c == 'V') { |
| set_bit(WDT_CAN_BE_CLOSED, |
| &wdt->status); |
| break; |
| } |
| } |
| } |
| wdt_enable(); |
| } |
| return len; |
| } |
| |
| static const struct watchdog_info ident = { |
| .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, |
| .identity = MODULE_NAME, |
| }; |
| |
| static long sp805_wdt_ioctl(struct file *file, unsigned int cmd, |
| unsigned long arg) |
| { |
| int ret = -ENOTTY; |
| unsigned int timeout; |
| |
| switch (cmd) { |
| case WDIOC_GETSUPPORT: |
| ret = copy_to_user((struct watchdog_info *)arg, &ident, |
| sizeof(ident)) ? -EFAULT : 0; |
| break; |
| |
| case WDIOC_GETSTATUS: |
| ret = put_user(0, (int *)arg); |
| break; |
| |
| case WDIOC_KEEPALIVE: |
| wdt_enable(); |
| ret = 0; |
| break; |
| |
| case WDIOC_SETTIMEOUT: |
| ret = get_user(timeout, (unsigned int *)arg); |
| if (ret) |
| break; |
| |
| wdt_setload(timeout); |
| |
| wdt_enable(); |
| /* Fall through */ |
| |
| case WDIOC_GETTIMEOUT: |
| ret = put_user(wdt->timeout, (unsigned int *)arg); |
| break; |
| case WDIOC_GETTIMELEFT: |
| ret = put_user(wdt_timeleft(), (unsigned int *)arg); |
| break; |
| } |
| return ret; |
| } |
| |
| static int sp805_wdt_open(struct inode *inode, struct file *file) |
| { |
| int ret = 0; |
| |
| if (test_and_set_bit(WDT_BUSY, &wdt->status)) |
| return -EBUSY; |
| |
| ret = clk_enable(wdt->clk); |
| if (ret) { |
| dev_err(&wdt->adev->dev, "clock enable fail"); |
| goto err; |
| } |
| |
| wdt_enable(); |
| |
| /* can not be closed, once enabled */ |
| clear_bit(WDT_CAN_BE_CLOSED, &wdt->status); |
| return nonseekable_open(inode, file); |
| |
| err: |
| clear_bit(WDT_BUSY, &wdt->status); |
| return ret; |
| } |
| |
| static int sp805_wdt_release(struct inode *inode, struct file *file) |
| { |
| if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) { |
| clear_bit(WDT_BUSY, &wdt->status); |
| dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n"); |
| return 0; |
| } |
| |
| wdt_disable(); |
| clk_disable(wdt->clk); |
| clear_bit(WDT_BUSY, &wdt->status); |
| |
| return 0; |
| } |
| |
| static const struct file_operations sp805_wdt_fops = { |
| .owner = THIS_MODULE, |
| .llseek = no_llseek, |
| .write = sp805_wdt_write, |
| .unlocked_ioctl = sp805_wdt_ioctl, |
| .open = sp805_wdt_open, |
| .release = sp805_wdt_release, |
| }; |
| |
| static struct miscdevice sp805_wdt_miscdev = { |
| .minor = WATCHDOG_MINOR, |
| .name = "watchdog", |
| .fops = &sp805_wdt_fops, |
| }; |
| |
| static int __devinit |
| sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id) |
| { |
| int ret = 0; |
| |
| if (!request_mem_region(adev->res.start, resource_size(&adev->res), |
| "sp805_wdt")) { |
| dev_warn(&adev->dev, "Failed to get memory region resource\n"); |
| ret = -ENOENT; |
| goto err; |
| } |
| |
| wdt = kzalloc(sizeof(*wdt), GFP_KERNEL); |
| if (!wdt) { |
| dev_warn(&adev->dev, "Kzalloc failed\n"); |
| ret = -ENOMEM; |
| goto err_kzalloc; |
| } |
| |
| wdt->clk = clk_get(&adev->dev, NULL); |
| if (IS_ERR(wdt->clk)) { |
| dev_warn(&adev->dev, "Clock not found\n"); |
| ret = PTR_ERR(wdt->clk); |
| goto err_clk_get; |
| } |
| |
| wdt->base = ioremap(adev->res.start, resource_size(&adev->res)); |
| if (!wdt->base) { |
| ret = -ENOMEM; |
| dev_warn(&adev->dev, "ioremap fail\n"); |
| goto err_ioremap; |
| } |
| |
| wdt->adev = adev; |
| spin_lock_init(&wdt->lock); |
| wdt_setload(DEFAULT_TIMEOUT); |
| |
| ret = misc_register(&sp805_wdt_miscdev); |
| if (ret < 0) { |
| dev_warn(&adev->dev, "cannot register misc device\n"); |
| goto err_misc_register; |
| } |
| |
| dev_info(&adev->dev, "registration successful\n"); |
| return 0; |
| |
| err_misc_register: |
| iounmap(wdt->base); |
| err_ioremap: |
| clk_put(wdt->clk); |
| err_clk_get: |
| kfree(wdt); |
| wdt = NULL; |
| err_kzalloc: |
| release_mem_region(adev->res.start, resource_size(&adev->res)); |
| err: |
| dev_err(&adev->dev, "Probe Failed!!!\n"); |
| return ret; |
| } |
| |
| static int __devexit sp805_wdt_remove(struct amba_device *adev) |
| { |
| misc_deregister(&sp805_wdt_miscdev); |
| iounmap(wdt->base); |
| clk_put(wdt->clk); |
| kfree(wdt); |
| release_mem_region(adev->res.start, resource_size(&adev->res)); |
| |
| return 0; |
| } |
| |
| #ifdef CONFIG_PM |
| static int sp805_wdt_suspend(struct device *dev) |
| { |
| if (test_bit(WDT_BUSY, &wdt->status)) { |
| wdt_disable(); |
| clk_disable(wdt->clk); |
| } |
| |
| return 0; |
| } |
| |
| static int sp805_wdt_resume(struct device *dev) |
| { |
| int ret = 0; |
| |
| if (test_bit(WDT_BUSY, &wdt->status)) { |
| ret = clk_enable(wdt->clk); |
| if (ret) { |
| dev_err(dev, "clock enable fail"); |
| return ret; |
| } |
| wdt_enable(); |
| } |
| |
| return ret; |
| } |
| #endif /* CONFIG_PM */ |
| |
| static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend, |
| sp805_wdt_resume); |
| |
| static struct amba_id sp805_wdt_ids[] = { |
| { |
| .id = 0x00141805, |
| .mask = 0x00ffffff, |
| }, |
| { 0, 0 }, |
| }; |
| |
| MODULE_DEVICE_TABLE(amba, sp805_wdt_ids); |
| |
| static struct amba_driver sp805_wdt_driver = { |
| .drv = { |
| .name = MODULE_NAME, |
| .pm = &sp805_wdt_dev_pm_ops, |
| }, |
| .id_table = sp805_wdt_ids, |
| .probe = sp805_wdt_probe, |
| .remove = __devexit_p(sp805_wdt_remove), |
| }; |
| |
| module_amba_driver(sp805_wdt_driver); |
| |
| module_param(nowayout, bool, 0); |
| MODULE_PARM_DESC(nowayout, |
| "Set to 1 to keep watchdog running after device release"); |
| |
| MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>"); |
| MODULE_DESCRIPTION("ARM SP805 Watchdog Driver"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |