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324 lines
7.5 KiB
324 lines
7.5 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface |
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* |
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* Author: James Chapman <[email protected]> |
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* |
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* Platform-specific setup code should configure the dog to generate |
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* interrupt or reset as required. This code only enables/disables |
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* and services the watchdog. |
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* |
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* Derived from mpc8xx_wdt.c, with the following copyright. |
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* |
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* 2002 (c) Florian Schirmer <[email protected]> |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/fs.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/miscdevice.h> |
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#include <linux/module.h> |
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#include <linux/watchdog.h> |
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#include <linux/platform_device.h> |
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#include <linux/mv643xx.h> |
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#include <linux/uaccess.h> |
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#include <linux/io.h> |
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#define MV64x60_WDT_WDC_OFFSET 0 |
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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 MV64x60_WDC_ENABLE_SHIFT 24 |
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#define MV64x60_WDC_SERVICE_SHIFT 26 |
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#define MV64x60_WDC_ENABLED_SHIFT 31 |
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#define MV64x60_WDC_ENABLED_TRUE 1 |
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#define MV64x60_WDC_ENABLED_FALSE 0 |
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/* Flags bits */ |
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#define MV64x60_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 *mv64x60_wdt_regs; |
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static int mv64x60_wdt_timeout; |
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static int mv64x60_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(mv64x60_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, |
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"Watchdog cannot be stopped once started (default=" |
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
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static int mv64x60_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(&mv64x60_wdt_spinlock); |
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data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET); |
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enabled = (data >> MV64x60_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) | mv64x60_wdt_count; |
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writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET); |
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data = (2 << field_shift) | mv64x60_wdt_count; |
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writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET); |
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ret = 1; |
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} |
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spin_unlock(&mv64x60_wdt_spinlock); |
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return ret; |
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} |
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static void mv64x60_wdt_service(void) |
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{ |
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mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE, |
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MV64x60_WDC_SERVICE_SHIFT); |
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} |
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static void mv64x60_wdt_handler_enable(void) |
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{ |
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if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE, |
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MV64x60_WDC_ENABLE_SHIFT)) { |
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mv64x60_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 mv64x60_wdt_handler_disable(void) |
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{ |
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if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE, |
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MV64x60_WDC_ENABLE_SHIFT)) |
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pr_notice("watchdog deactivated\n"); |
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} |
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static void mv64x60_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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mv64x60_wdt_count = timeout * bus_clk >> 8; |
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mv64x60_wdt_timeout = timeout; |
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} |
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static int mv64x60_wdt_open(struct inode *inode, struct file *file) |
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{ |
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if (test_and_set_bit(MV64x60_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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mv64x60_wdt_handler_enable(); |
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return stream_open(inode, file); |
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} |
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static int mv64x60_wdt_release(struct inode *inode, struct file *file) |
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{ |
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if (expect_close == 42) |
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mv64x60_wdt_handler_disable(); |
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else { |
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pr_crit("unexpected close, not stopping timer!\n"); |
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mv64x60_wdt_service(); |
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} |
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expect_close = 0; |
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clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags); |
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return 0; |
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} |
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static ssize_t mv64x60_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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mv64x60_wdt_service(); |
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} |
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return len; |
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} |
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static long mv64x60_wdt_ioctl(struct file *file, |
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unsigned int cmd, 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 | |
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WDIOF_MAGICCLOSE | |
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WDIOF_KEEPALIVEPING, |
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.firmware_version = 0, |
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.identity = "MV64x60 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_GETTEMP: |
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return -EOPNOTSUPP; |
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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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mv64x60_wdt_handler_disable(); |
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if (options & WDIOS_ENABLECARD) |
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mv64x60_wdt_handler_enable(); |
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break; |
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case WDIOC_KEEPALIVE: |
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mv64x60_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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mv64x60_wdt_set_timeout(timeout); |
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fallthrough; |
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case WDIOC_GETTIMEOUT: |
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if (put_user(mv64x60_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 const struct file_operations mv64x60_wdt_fops = { |
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.owner = THIS_MODULE, |
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.llseek = no_llseek, |
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.write = mv64x60_wdt_write, |
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.unlocked_ioctl = mv64x60_wdt_ioctl, |
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.compat_ioctl = compat_ptr_ioctl, |
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.open = mv64x60_wdt_open, |
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.release = mv64x60_wdt_release, |
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}; |
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static struct miscdevice mv64x60_wdt_miscdev = { |
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.minor = WATCHDOG_MINOR, |
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.name = "watchdog", |
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.fops = &mv64x60_wdt_fops, |
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}; |
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static int mv64x60_wdt_probe(struct platform_device *dev) |
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{ |
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struct mv64x60_wdt_pdata *pdata = dev_get_platdata(&dev->dev); |
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struct resource *r; |
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int timeout = 10; |
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bus_clk = 133; /* in MHz */ |
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if (pdata) { |
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timeout = pdata->timeout; |
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bus_clk = pdata->bus_clk; |
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} |
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/* Since bus_clk is truncated MHz, actual frequency could be |
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* up to 1MHz higher. Round up, since it's better to time out |
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* too late than too soon. |
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*/ |
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bus_clk++; |
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bus_clk *= 1000000; /* convert to Hz */ |
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r = platform_get_resource(dev, IORESOURCE_MEM, 0); |
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if (!r) |
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return -ENODEV; |
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mv64x60_wdt_regs = devm_ioremap(&dev->dev, r->start, resource_size(r)); |
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if (mv64x60_wdt_regs == NULL) |
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return -ENOMEM; |
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mv64x60_wdt_set_timeout(timeout); |
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mv64x60_wdt_handler_disable(); /* in case timer was already running */ |
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return misc_register(&mv64x60_wdt_miscdev); |
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} |
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static int mv64x60_wdt_remove(struct platform_device *dev) |
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{ |
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misc_deregister(&mv64x60_wdt_miscdev); |
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mv64x60_wdt_handler_disable(); |
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return 0; |
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} |
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static struct platform_driver mv64x60_wdt_driver = { |
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.probe = mv64x60_wdt_probe, |
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.remove = mv64x60_wdt_remove, |
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.driver = { |
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.name = MV64x60_WDT_NAME, |
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}, |
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}; |
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static int __init mv64x60_wdt_init(void) |
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{ |
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pr_info("MV64x60 watchdog driver\n"); |
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return platform_driver_register(&mv64x60_wdt_driver); |
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} |
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static void __exit mv64x60_wdt_exit(void) |
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{ |
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platform_driver_unregister(&mv64x60_wdt_driver); |
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} |
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module_init(mv64x60_wdt_init); |
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module_exit(mv64x60_wdt_exit); |
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MODULE_AUTHOR("James Chapman <[email protected]>"); |
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MODULE_DESCRIPTION("MV64x60 watchdog driver"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:" MV64x60_WDT_NAME);
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