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331 lines
7.3 KiB
331 lines
7.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* GE watchdog userspace interface |
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* |
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* Author: Martyn Welch <[email protected]> |
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* |
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* Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. |
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* |
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* Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface) |
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* Author: James Chapman <[email protected]> |
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*/ |
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/* TODO: |
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* This driver does not provide support for the hardwares capability of sending |
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* an interrupt at a programmable threshold. |
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* |
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* This driver currently can only support 1 watchdog - there are 2 in the |
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* hardware that this driver supports. Thus one could be configured as a |
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* process-based watchdog (via /dev/watchdog), the second (using the interrupt |
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* capabilities) a kernel-based watchdog. |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/kernel.h> |
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#include <linux/compiler.h> |
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#include <linux/init.h> |
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#include <linux/module.h> |
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#include <linux/miscdevice.h> |
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#include <linux/watchdog.h> |
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#include <linux/fs.h> |
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#include <linux/of.h> |
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#include <linux/of_address.h> |
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#include <linux/of_platform.h> |
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#include <linux/io.h> |
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#include <linux/uaccess.h> |
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#include <sysdev/fsl_soc.h> |
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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 GEF_WDC_ENABLE_SHIFT 24 |
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#define GEF_WDC_SERVICE_SHIFT 26 |
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#define GEF_WDC_ENABLED_SHIFT 31 |
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#define GEF_WDC_ENABLED_TRUE 1 |
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#define GEF_WDC_ENABLED_FALSE 0 |
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/* Flags bits */ |
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#define GEF_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 *gef_wdt_regs; |
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static int gef_wdt_timeout; |
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static int gef_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(gef_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, "Watchdog cannot be stopped once started (default=" |
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
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static int gef_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(&gef_wdt_spinlock); |
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data = ioread32be(gef_wdt_regs); |
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enabled = (data >> GEF_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) | gef_wdt_count; |
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iowrite32be(data, gef_wdt_regs); |
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data = (2 << field_shift) | gef_wdt_count; |
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iowrite32be(data, gef_wdt_regs); |
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ret = 1; |
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} |
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spin_unlock(&gef_wdt_spinlock); |
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return ret; |
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} |
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static void gef_wdt_service(void) |
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{ |
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gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, |
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GEF_WDC_SERVICE_SHIFT); |
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} |
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static void gef_wdt_handler_enable(void) |
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{ |
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if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE, |
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GEF_WDC_ENABLE_SHIFT)) { |
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gef_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 gef_wdt_handler_disable(void) |
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{ |
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if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE, |
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GEF_WDC_ENABLE_SHIFT)) |
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pr_notice("watchdog deactivated\n"); |
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} |
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static void gef_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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/* Register only holds upper 24 bits, bit shifted into lower 24 */ |
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gef_wdt_count = (timeout * bus_clk) >> 8; |
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gef_wdt_timeout = timeout; |
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} |
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static ssize_t gef_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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gef_wdt_service(); |
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} |
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return len; |
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} |
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static long gef_wdt_ioctl(struct file *file, unsigned int cmd, |
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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 | WDIOF_MAGICCLOSE | |
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WDIOF_KEEPALIVEPING, |
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.firmware_version = 0, |
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.identity = "GE 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_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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gef_wdt_handler_disable(); |
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if (options & WDIOS_ENABLECARD) |
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gef_wdt_handler_enable(); |
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break; |
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case WDIOC_KEEPALIVE: |
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gef_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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gef_wdt_set_timeout(timeout); |
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fallthrough; |
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case WDIOC_GETTIMEOUT: |
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if (put_user(gef_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 int gef_wdt_open(struct inode *inode, struct file *file) |
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{ |
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if (test_and_set_bit(GEF_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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gef_wdt_handler_enable(); |
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return stream_open(inode, file); |
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} |
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static int gef_wdt_release(struct inode *inode, struct file *file) |
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{ |
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if (expect_close == 42) |
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gef_wdt_handler_disable(); |
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else { |
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pr_crit("unexpected close, not stopping timer!\n"); |
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gef_wdt_service(); |
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} |
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expect_close = 0; |
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clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags); |
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return 0; |
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} |
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static const struct file_operations gef_wdt_fops = { |
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.owner = THIS_MODULE, |
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.llseek = no_llseek, |
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.write = gef_wdt_write, |
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.unlocked_ioctl = gef_wdt_ioctl, |
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.compat_ioctl = compat_ptr_ioctl, |
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.open = gef_wdt_open, |
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.release = gef_wdt_release, |
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}; |
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static struct miscdevice gef_wdt_miscdev = { |
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.minor = WATCHDOG_MINOR, |
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.name = "watchdog", |
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.fops = &gef_wdt_fops, |
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}; |
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static int gef_wdt_probe(struct platform_device *dev) |
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{ |
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int timeout = 10; |
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u32 freq; |
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bus_clk = 133; /* in MHz */ |
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freq = fsl_get_sys_freq(); |
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if (freq != -1) |
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bus_clk = freq; |
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/* Map devices registers into memory */ |
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gef_wdt_regs = of_iomap(dev->dev.of_node, 0); |
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if (gef_wdt_regs == NULL) |
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return -ENOMEM; |
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gef_wdt_set_timeout(timeout); |
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gef_wdt_handler_disable(); /* in case timer was already running */ |
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return misc_register(&gef_wdt_miscdev); |
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} |
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static int gef_wdt_remove(struct platform_device *dev) |
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{ |
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misc_deregister(&gef_wdt_miscdev); |
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gef_wdt_handler_disable(); |
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iounmap(gef_wdt_regs); |
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return 0; |
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} |
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static const struct of_device_id gef_wdt_ids[] = { |
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{ |
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.compatible = "gef,fpga-wdt", |
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}, |
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{}, |
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}; |
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MODULE_DEVICE_TABLE(of, gef_wdt_ids); |
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static struct platform_driver gef_wdt_driver = { |
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.driver = { |
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.name = "gef_wdt", |
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.of_match_table = gef_wdt_ids, |
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}, |
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.probe = gef_wdt_probe, |
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.remove = gef_wdt_remove, |
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}; |
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static int __init gef_wdt_init(void) |
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{ |
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pr_info("GE watchdog driver\n"); |
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return platform_driver_register(&gef_wdt_driver); |
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} |
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static void __exit gef_wdt_exit(void) |
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{ |
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platform_driver_unregister(&gef_wdt_driver); |
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} |
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module_init(gef_wdt_init); |
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module_exit(gef_wdt_exit); |
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MODULE_AUTHOR("Martyn Welch <[email protected]>"); |
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MODULE_DESCRIPTION("GE watchdog driver"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:gef_wdt");
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