| /* |
| * Watchdog Device Driver for Xilinx axi/xps_timebase_wdt |
| * |
| * (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/kernel.h> |
| #include <linux/fs.h> |
| #include <linux/miscdevice.h> |
| #include <linux/init.h> |
| #include <linux/ioport.h> |
| #include <linux/watchdog.h> |
| #include <linux/io.h> |
| #include <linux/uaccess.h> |
| #include <linux/of.h> |
| #include <linux/of_device.h> |
| #include <linux/of_address.h> |
| |
| /* Register offsets for the Wdt device */ |
| #define XWT_TWCSR0_OFFSET 0x0 /* Control/Status Register0 */ |
| #define XWT_TWCSR1_OFFSET 0x4 /* Control/Status Register1 */ |
| #define XWT_TBR_OFFSET 0x8 /* Timebase Register Offset */ |
| |
| /* Control/Status Register Masks */ |
| #define XWT_CSR0_WRS_MASK 0x00000008 /* Reset status */ |
| #define XWT_CSR0_WDS_MASK 0x00000004 /* Timer state */ |
| #define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */ |
| |
| /* Control/Status Register 0/1 bits */ |
| #define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */ |
| |
| /* SelfTest constants */ |
| #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000 |
| #define XWT_TIMER_FAILED 0xFFFFFFFF |
| |
| #define WATCHDOG_NAME "Xilinx Watchdog" |
| #define PFX WATCHDOG_NAME ": " |
| |
| struct xwdt_device { |
| struct resource res; |
| void __iomem *base; |
| u32 nowayout; |
| u32 wdt_interval; |
| u32 boot_status; |
| }; |
| |
| static struct xwdt_device xdev; |
| |
| static u32 timeout; |
| static u32 control_status_reg; |
| static u8 expect_close; |
| static u8 no_timeout; |
| static unsigned long driver_open; |
| |
| static DEFINE_SPINLOCK(spinlock); |
| |
| static void xwdt_start(void) |
| { |
| spin_lock(&spinlock); |
| |
| /* Clean previous status and enable the watchdog timer */ |
| control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET); |
| control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK); |
| |
| iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK), |
| xdev.base + XWT_TWCSR0_OFFSET); |
| |
| iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET); |
| |
| spin_unlock(&spinlock); |
| } |
| |
| static void xwdt_stop(void) |
| { |
| spin_lock(&spinlock); |
| |
| control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET); |
| |
| iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK), |
| xdev.base + XWT_TWCSR0_OFFSET); |
| |
| iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET); |
| |
| spin_unlock(&spinlock); |
| pr_info("Stopped!\n"); |
| } |
| |
| static void xwdt_keepalive(void) |
| { |
| spin_lock(&spinlock); |
| |
| control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET); |
| control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK); |
| iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET); |
| |
| spin_unlock(&spinlock); |
| } |
| |
| static void xwdt_get_status(int *status) |
| { |
| int new_status; |
| |
| spin_lock(&spinlock); |
| |
| control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET); |
| new_status = ((control_status_reg & |
| (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK)) != 0); |
| spin_unlock(&spinlock); |
| |
| *status = 0; |
| if (new_status & 1) |
| *status |= WDIOF_CARDRESET; |
| } |
| |
| static u32 xwdt_selftest(void) |
| { |
| int i; |
| u32 timer_value1; |
| u32 timer_value2; |
| |
| spin_lock(&spinlock); |
| |
| timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET); |
| timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET); |
| |
| for (i = 0; |
| ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) && |
| (timer_value2 == timer_value1)); i++) { |
| timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET); |
| } |
| |
| spin_unlock(&spinlock); |
| |
| if (timer_value2 != timer_value1) |
| return ~XWT_TIMER_FAILED; |
| else |
| return XWT_TIMER_FAILED; |
| } |
| |
| static int xwdt_open(struct inode *inode, struct file *file) |
| { |
| /* Only one process can handle the wdt at a time */ |
| if (test_and_set_bit(0, &driver_open)) |
| return -EBUSY; |
| |
| /* Make sure that the module are always loaded...*/ |
| if (xdev.nowayout) |
| __module_get(THIS_MODULE); |
| |
| xwdt_start(); |
| pr_info("Started...\n"); |
| |
| return nonseekable_open(inode, file); |
| } |
| |
| static int xwdt_release(struct inode *inode, struct file *file) |
| { |
| if (expect_close == 42) { |
| xwdt_stop(); |
| } else { |
| pr_crit("Unexpected close, not stopping watchdog!\n"); |
| xwdt_keepalive(); |
| } |
| |
| clear_bit(0, &driver_open); |
| expect_close = 0; |
| return 0; |
| } |
| |
| /* |
| * xwdt_write: |
| * @file: file handle to the watchdog |
| * @buf: buffer to write (unused as data does not matter here |
| * @count: count of bytes |
| * @ppos: pointer to the position to write. No seeks allowed |
| * |
| * A write to a watchdog device is defined as a keepalive signal. Any |
| * write of data will do, as we don't define content meaning. |
| */ |
| static ssize_t xwdt_write(struct file *file, const char __user *buf, |
| size_t len, loff_t *ppos) |
| { |
| if (len) { |
| if (!xdev.nowayout) { |
| size_t i; |
| |
| /* In case it was set long ago */ |
| expect_close = 0; |
| |
| for (i = 0; i != len; i++) { |
| char c; |
| |
| if (get_user(c, buf + i)) |
| return -EFAULT; |
| if (c == 'V') |
| expect_close = 42; |
| } |
| } |
| xwdt_keepalive(); |
| } |
| return len; |
| } |
| |
| static const struct watchdog_info ident = { |
| .options = WDIOF_MAGICCLOSE | |
| WDIOF_KEEPALIVEPING, |
| .firmware_version = 1, |
| .identity = WATCHDOG_NAME, |
| }; |
| |
| /* |
| * xwdt_ioctl: |
| * @file: file handle to the device |
| * @cmd: watchdog command |
| * @arg: argument pointer |
| * |
| * The watchdog API defines a common set of functions for all watchdogs |
| * according to their available features. |
| */ |
| static long xwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
| { |
| int status; |
| |
| union { |
| struct watchdog_info __user *ident; |
| int __user *i; |
| } uarg; |
| |
| uarg.i = (int __user *)arg; |
| |
| switch (cmd) { |
| case WDIOC_GETSUPPORT: |
| return copy_to_user(uarg.ident, &ident, |
| sizeof(ident)) ? -EFAULT : 0; |
| |
| case WDIOC_GETBOOTSTATUS: |
| return put_user(xdev.boot_status, uarg.i); |
| |
| case WDIOC_GETSTATUS: |
| xwdt_get_status(&status); |
| return put_user(status, uarg.i); |
| |
| case WDIOC_KEEPALIVE: |
| xwdt_keepalive(); |
| return 0; |
| |
| case WDIOC_GETTIMEOUT: |
| if (no_timeout) |
| return -ENOTTY; |
| else |
| return put_user(timeout, uarg.i); |
| |
| default: |
| return -ENOTTY; |
| } |
| } |
| |
| static const struct file_operations xwdt_fops = { |
| .owner = THIS_MODULE, |
| .llseek = no_llseek, |
| .write = xwdt_write, |
| .open = xwdt_open, |
| .release = xwdt_release, |
| .unlocked_ioctl = xwdt_ioctl, |
| }; |
| |
| static struct miscdevice xwdt_miscdev = { |
| .minor = WATCHDOG_MINOR, |
| .name = "watchdog", |
| .fops = &xwdt_fops, |
| }; |
| |
| static int xwdt_probe(struct platform_device *pdev) |
| { |
| int rc; |
| u32 *tmptr; |
| u32 *pfreq; |
| |
| no_timeout = 0; |
| |
| pfreq = (u32 *)of_get_property(pdev->dev.of_node, |
| "clock-frequency", NULL); |
| |
| if (pfreq == NULL) { |
| pr_warn("The watchdog clock frequency cannot be obtained!\n"); |
| no_timeout = 1; |
| } |
| |
| rc = of_address_to_resource(pdev->dev.of_node, 0, &xdev.res); |
| if (rc) { |
| pr_warn("invalid address!\n"); |
| return rc; |
| } |
| |
| tmptr = (u32 *)of_get_property(pdev->dev.of_node, |
| "xlnx,wdt-interval", NULL); |
| if (tmptr == NULL) { |
| pr_warn("Parameter \"xlnx,wdt-interval\" not found in device tree!\n"); |
| no_timeout = 1; |
| } else { |
| xdev.wdt_interval = *tmptr; |
| } |
| |
| tmptr = (u32 *)of_get_property(pdev->dev.of_node, |
| "xlnx,wdt-enable-once", NULL); |
| if (tmptr == NULL) { |
| pr_warn("Parameter \"xlnx,wdt-enable-once\" not found in device tree!\n"); |
| xdev.nowayout = WATCHDOG_NOWAYOUT; |
| } |
| |
| /* |
| * Twice of the 2^wdt_interval / freq because the first wdt overflow is |
| * ignored (interrupt), reset is only generated at second wdt overflow |
| */ |
| if (!no_timeout) |
| timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq); |
| |
| if (!request_mem_region(xdev.res.start, |
| xdev.res.end - xdev.res.start + 1, WATCHDOG_NAME)) { |
| rc = -ENXIO; |
| pr_err("memory request failure!\n"); |
| goto err_out; |
| } |
| |
| xdev.base = ioremap(xdev.res.start, xdev.res.end - xdev.res.start + 1); |
| if (xdev.base == NULL) { |
| rc = -ENOMEM; |
| pr_err("ioremap failure!\n"); |
| goto release_mem; |
| } |
| |
| rc = xwdt_selftest(); |
| if (rc == XWT_TIMER_FAILED) { |
| pr_err("SelfTest routine error!\n"); |
| goto unmap_io; |
| } |
| |
| xwdt_get_status(&xdev.boot_status); |
| |
| rc = misc_register(&xwdt_miscdev); |
| if (rc) { |
| pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
| xwdt_miscdev.minor, rc); |
| goto unmap_io; |
| } |
| |
| if (no_timeout) |
| pr_info("driver loaded (timeout=? sec, nowayout=%d)\n", |
| xdev.nowayout); |
| else |
| pr_info("driver loaded (timeout=%d sec, nowayout=%d)\n", |
| timeout, xdev.nowayout); |
| |
| expect_close = 0; |
| clear_bit(0, &driver_open); |
| |
| return 0; |
| |
| unmap_io: |
| iounmap(xdev.base); |
| release_mem: |
| release_mem_region(xdev.res.start, resource_size(&xdev.res)); |
| err_out: |
| return rc; |
| } |
| |
| static int xwdt_remove(struct platform_device *dev) |
| { |
| misc_deregister(&xwdt_miscdev); |
| iounmap(xdev.base); |
| release_mem_region(xdev.res.start, resource_size(&xdev.res)); |
| |
| return 0; |
| } |
| |
| /* Match table for of_platform binding */ |
| static struct of_device_id xwdt_of_match[] = { |
| { .compatible = "xlnx,xps-timebase-wdt-1.00.a", }, |
| { .compatible = "xlnx,xps-timebase-wdt-1.01.a", }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, xwdt_of_match); |
| |
| static struct platform_driver xwdt_driver = { |
| .probe = xwdt_probe, |
| .remove = xwdt_remove, |
| .driver = { |
| .owner = THIS_MODULE, |
| .name = WATCHDOG_NAME, |
| .of_match_table = xwdt_of_match, |
| }, |
| }; |
| |
| module_platform_driver(xwdt_driver); |
| |
| MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>"); |
| MODULE_DESCRIPTION("Xilinx Watchdog driver"); |
| MODULE_LICENSE("GPL v2"); |
| MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |