diff options
Diffstat (limited to 'drivers/watchdog/booke_wdt.c')
| -rw-r--r-- | drivers/watchdog/booke_wdt.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/drivers/watchdog/booke_wdt.c b/drivers/watchdog/booke_wdt.c new file mode 100644 index 000000000..932a03f44 --- /dev/null +++ b/drivers/watchdog/booke_wdt.c @@ -0,0 +1,243 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Watchdog timer for PowerPC Book-E systems + * + * Author: Matthew McClintock + * Maintainer: Kumar Gala <galak@kernel.crashing.org> + * + * Copyright 2005, 2008, 2010-2011 Freescale Semiconductor Inc. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/smp.h> +#include <linux/watchdog.h> + +#include <asm/reg_booke.h> +#include <asm/time.h> +#include <asm/div64.h> + +/* If the kernel parameter wdt=1, the watchdog will be enabled at boot. + * Also, the wdt_period sets the watchdog timer period timeout. + * For E500 cpus the wdt_period sets which bit changing from 0->1 will + * trigger a watchdog timeout. This watchdog timeout will occur 3 times, the + * first time nothing will happen, the second time a watchdog exception will + * occur, and the final time the board will reset. + */ + + +#ifdef CONFIG_PPC_E500 +#define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) +#define WDTP_MASK (WDTP(0x3f)) +#else +#define WDTP(x) (TCR_WP(x)) +#define WDTP_MASK (TCR_WP_MASK) +#endif + +static bool booke_wdt_enabled; +module_param(booke_wdt_enabled, bool, 0); +static int booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; +module_param(booke_wdt_period, int, 0); +static bool nowayout = WATCHDOG_NOWAYOUT; +module_param(nowayout, bool, 0); +MODULE_PARM_DESC(nowayout, + "Watchdog cannot be stopped once started (default=" + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); + +#ifdef CONFIG_PPC_E500 + +/* For the specified period, determine the number of seconds + * corresponding to the reset time. There will be a watchdog + * exception at approximately 3/5 of this time. + * + * The formula to calculate this is given by: + * 2.5 * (2^(63-period+1)) / timebase_freq + * + * In order to simplify things, we assume that period is + * at least 1. This will still result in a very long timeout. + */ +static unsigned long long period_to_sec(unsigned int period) +{ + unsigned long long tmp = 1ULL << (64 - period); + unsigned long tmp2 = ppc_tb_freq; + + /* tmp may be a very large number and we don't want to overflow, + * so divide the timebase freq instead of multiplying tmp + */ + tmp2 = tmp2 / 5 * 2; + + do_div(tmp, tmp2); + return tmp; +} + +/* + * This procedure will find the highest period which will give a timeout + * greater than the one required. e.g. for a bus speed of 66666666 and + * a parameter of 2 secs, then this procedure will return a value of 38. + */ +static unsigned int sec_to_period(unsigned int secs) +{ + unsigned int period; + for (period = 63; period > 0; period--) { + if (period_to_sec(period) >= secs) + return period; + } + return 0; +} + +#define MAX_WDT_TIMEOUT period_to_sec(1) + +#else /* CONFIG_PPC_E500 */ + +static unsigned long long period_to_sec(unsigned int period) +{ + return period; +} + +static unsigned int sec_to_period(unsigned int secs) +{ + return secs; +} + +#define MAX_WDT_TIMEOUT 3 /* from Kconfig */ + +#endif /* !CONFIG_PPC_E500 */ + +static void __booke_wdt_set(void *data) +{ + u32 val; + struct watchdog_device *wdog = data; + + val = mfspr(SPRN_TCR); + val &= ~WDTP_MASK; + val |= WDTP(sec_to_period(wdog->timeout)); + + mtspr(SPRN_TCR, val); +} + +static void booke_wdt_set(void *data) +{ + on_each_cpu(__booke_wdt_set, data, 0); +} + +static void __booke_wdt_ping(void *data) +{ + mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); +} + +static int booke_wdt_ping(struct watchdog_device *wdog) +{ + on_each_cpu(__booke_wdt_ping, NULL, 0); + + return 0; +} + +static void __booke_wdt_enable(void *data) +{ + u32 val; + struct watchdog_device *wdog = data; + + /* clear status before enabling watchdog */ + __booke_wdt_ping(NULL); + val = mfspr(SPRN_TCR); + val &= ~WDTP_MASK; + val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(sec_to_period(wdog->timeout))); + + mtspr(SPRN_TCR, val); +} + +/** + * __booke_wdt_disable - disable the watchdog on the given CPU + * + * This function is called on each CPU. It disables the watchdog on that CPU. + * + * TCR[WRC] cannot be changed once it has been set to non-zero, but we can + * effectively disable the watchdog by setting its period to the maximum value. + */ +static void __booke_wdt_disable(void *data) +{ + u32 val; + + val = mfspr(SPRN_TCR); + val &= ~(TCR_WIE | WDTP_MASK); + mtspr(SPRN_TCR, val); + + /* clear status to make sure nothing is pending */ + __booke_wdt_ping(NULL); + +} + +static int booke_wdt_start(struct watchdog_device *wdog) +{ + on_each_cpu(__booke_wdt_enable, wdog, 0); + pr_debug("watchdog enabled (timeout = %u sec)\n", wdog->timeout); + + return 0; +} + +static int booke_wdt_stop(struct watchdog_device *wdog) +{ + on_each_cpu(__booke_wdt_disable, NULL, 0); + pr_debug("watchdog disabled\n"); + + return 0; +} + +static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev, + unsigned int timeout) +{ + wdt_dev->timeout = timeout; + booke_wdt_set(wdt_dev); + + return 0; +} + +static struct watchdog_info booke_wdt_info __ro_after_init = { + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, + .identity = "PowerPC Book-E Watchdog", +}; + +static const struct watchdog_ops booke_wdt_ops = { + .owner = THIS_MODULE, + .start = booke_wdt_start, + .stop = booke_wdt_stop, + .ping = booke_wdt_ping, + .set_timeout = booke_wdt_set_timeout, +}; + +static struct watchdog_device booke_wdt_dev = { + .info = &booke_wdt_info, + .ops = &booke_wdt_ops, + .min_timeout = 1, +}; + +static void __exit booke_wdt_exit(void) +{ + watchdog_unregister_device(&booke_wdt_dev); +} + +static int __init booke_wdt_init(void) +{ + int ret = 0; + + pr_info("powerpc book-e watchdog driver loaded\n"); + booke_wdt_info.firmware_version = cur_cpu_spec->pvr_value; + booke_wdt_set_timeout(&booke_wdt_dev, + period_to_sec(booke_wdt_period)); + watchdog_set_nowayout(&booke_wdt_dev, nowayout); + booke_wdt_dev.max_timeout = MAX_WDT_TIMEOUT; + if (booke_wdt_enabled) + booke_wdt_start(&booke_wdt_dev); + + ret = watchdog_register_device(&booke_wdt_dev); + + return ret; +} + +module_init(booke_wdt_init); +module_exit(booke_wdt_exit); + +MODULE_ALIAS("booke_wdt"); +MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); +MODULE_LICENSE("GPL"); |