--- /dev/null
+/*
+ * 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.
+ *
+ * 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/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 watchog 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_FSL_BOOK3E
+#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);
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
+
+/* 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
+ * 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_FSL_BOOK3E */
+
+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_FSL_BOOK3E */
+
+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)
+{
+ if (timeout > MAX_WDT_TIMEOUT)
+ return -EINVAL;
+ wdt_dev->timeout = timeout;
+ booke_wdt_set(wdt_dev);
+
+ return 0;
+}
+
+static struct watchdog_info booke_wdt_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+ .identity = "PowerPC Book-E Watchdog",
+};
+
+static 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,
+ .max_timeout = 0xFFFF
+};
+
+static void __exit booke_wdt_exit(void)
+{
+ watchdog_unregister_device(&booke_wdt_dev);
+}
+
+static int __init booke_wdt_init(void)
+{
+ int ret = 0;
+ bool nowayout = WATCHDOG_NOWAYOUT;
+
+ 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);
+ 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");
Code Review / kvmfornfv.git / blobdiff