[PATCHv2 2/3] mpc52xx/wdt: merge WDT code into the GPT driver
Albrecht Dreß
albrecht.dress at arcor.de
Fri Nov 13 05:44:47 EST 2009
Merge the WDT code into the GPT interface.
Signed-off-by: Albrecht Dreß <albrecht.dress at arcor.de>
---
Change against v1: fully merge the wdt api into this file.
Note: The patch does also include the tiny GPT api changes from
<http://lists.ozlabs.org/pipermail/linuxppc-dev/2009-November/077647.html>.
arch/powerpc/include/asm/mpc52xx.h | 5 +-
arch/powerpc/platforms/52xx/mpc52xx_gpt.c | 328 +++++++++++++++++++++++++++--
2 files changed, 312 insertions(+), 21 deletions(-)
diff --git a/arch/powerpc/include/asm/mpc52xx.h b/arch/powerpc/include/asm/mpc52xx.h
index 707ab75..b664ce7 100644
--- a/arch/powerpc/include/asm/mpc52xx.h
+++ b/arch/powerpc/include/asm/mpc52xx.h
@@ -279,9 +279,10 @@ extern void mpc52xx_restart(char *cmd);
/* mpc52xx_gpt.c */
struct mpc52xx_gpt_priv;
extern struct mpc52xx_gpt_priv *mpc52xx_gpt_from_irq(int irq);
-extern int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, int period,
+extern int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, u64 period,
int continuous);
-extern void mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt);
+extern u64 mpc52xx_gpt_timer_period(struct mpc52xx_gpt_priv *gpt);
+extern int mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt);
/* mpc52xx_lpbfifo.c */
#define MPC52XX_LPBFIFO_FLAG_READ (0)
diff --git a/arch/powerpc/platforms/52xx/mpc52xx_gpt.c b/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
index 2c3fa13..42caecf 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_gpt.c
@@ -16,8 +16,14 @@
* output signals or measure input signals.
*
* This driver supports the GPIO and IRQ controller functions of the GPT
- * device. Timer functions are not yet supported, nor is the watchdog
- * timer.
+ * device. Timer functions are not yet supported.
+ *
+ * The timer gpt0 can be used as watchdog (wdt). If the wdt mode is used,
+ * this prevents the use of any gpt0 gpt function (i.e. they will fail with
+ * -EBUSY). Thus, the safety wdt function always has precedence over the gpt
+ * function. If the kernel has been compiled with CONFIG_WATCHDOG_NOWAYOUT,
+ * this means that gpt0 is locked in wdt mode until the next reboot - this
+ * may be a requirement in safety applications.
*
* To use the GPIO function, the following two properties must be added
* to the device tree node for the gpt device (typically in the .dts file
@@ -56,11 +62,14 @@
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/kernel.h>
+#include <linux/watchdog.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
#include <asm/div64.h>
#include <asm/mpc52xx.h>
MODULE_DESCRIPTION("Freescale MPC52xx gpt driver");
-MODULE_AUTHOR("Sascha Hauer, Grant Likely");
+MODULE_AUTHOR("Sascha Hauer, Grant Likely, Albrecht Dreß");
MODULE_LICENSE("GPL");
/**
@@ -70,6 +79,9 @@ MODULE_LICENSE("GPL");
* @lock: spinlock to coordinate between different functions.
* @of_gc: of_gpio_chip instance structure; used when GPIO is enabled
* @irqhost: Pointer to irq_host instance; used when IRQ mode is supported
+ * @wdt_mode: only relevant for gpt0: bit 0 (MPC52xx_GPT_CAN_WDT) indicates
+ * if the gpt may be used as wdt, bit 1 (MPC52xx_GPT_IS_WDT) indicates
+ * if the timer is actively used as wdt which blocks gpt functions
*/
struct mpc52xx_gpt_priv {
struct list_head list; /* List of all GPT devices */
@@ -78,6 +90,7 @@ struct mpc52xx_gpt_priv {
spinlock_t lock;
struct irq_host *irqhost;
u32 ipb_freq;
+ u8 wdt_mode;
#if defined(CONFIG_GPIOLIB)
struct of_gpio_chip of_gc;
@@ -101,14 +114,21 @@ DEFINE_MUTEX(mpc52xx_gpt_list_mutex);
#define MPC52xx_GPT_MODE_CONTINUOUS (0x0400)
#define MPC52xx_GPT_MODE_OPEN_DRAIN (0x0200)
#define MPC52xx_GPT_MODE_IRQ_EN (0x0100)
+#define MPC52xx_GPT_MODE_WDT_EN (0x8000)
#define MPC52xx_GPT_MODE_ICT_MASK (0x030000)
#define MPC52xx_GPT_MODE_ICT_RISING (0x010000)
#define MPC52xx_GPT_MODE_ICT_FALLING (0x020000)
#define MPC52xx_GPT_MODE_ICT_TOGGLE (0x030000)
+#define MPC52xx_GPT_MODE_WDT_PING (0xa5)
+
#define MPC52xx_GPT_STATUS_IRQMASK (0x000f)
+#define MPC52xx_GPT_CAN_WDT (1 << 0)
+#define MPC52xx_GPT_IS_WDT (1 << 1)
+
+
/* ---------------------------------------------------------------------
* Cascaded interrupt controller hooks
*/
@@ -375,16 +395,8 @@ struct mpc52xx_gpt_priv *mpc52xx_gpt_from_irq(int irq)
}
EXPORT_SYMBOL(mpc52xx_gpt_from_irq);
-/**
- * mpc52xx_gpt_start_timer - Set and enable the GPT timer
- * @gpt: Pointer to gpt private data structure
- * @period: period of timer
- * @continuous: set to 1 to make timer continuous free running
- *
- * An interrupt will be generated every time the timer fires
- */
-int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, int period,
- int continuous)
+static int mpc52xx_gpt_do_start(struct mpc52xx_gpt_priv *gpt, u64 period,
+ int continuous, int as_wdt)
{
u32 clear, set;
u64 clocks;
@@ -393,15 +405,19 @@ int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, int period,
clear = MPC52xx_GPT_MODE_MS_MASK | MPC52xx_GPT_MODE_CONTINUOUS;
set = MPC52xx_GPT_MODE_MS_GPIO | MPC52xx_GPT_MODE_COUNTER_ENABLE;
- if (continuous)
+ if (as_wdt) {
+ clear |= MPC52xx_GPT_MODE_IRQ_EN;
+ set |= MPC52xx_GPT_MODE_WDT_EN;
+ } else if (continuous)
set |= MPC52xx_GPT_MODE_CONTINUOUS;
/* Determine the number of clocks in the requested period. 64 bit
* arithmatic is done here to preserve the precision until the value
* is scaled back down into the u32 range. Period is in 'ns', bus
- * frequency is in Hz. */
- clocks = (u64)period * (u64)gpt->ipb_freq;
- do_div(clocks, 1000000000); /* Scale it down to ns range */
+ * frequency is in Hz. The maximum timeout @33MHz IPB clock is ~130
+ * seconds*/
+ clocks = period * (u64)gpt->ipb_freq;
+ do_div(clocks, 1000000000ULL); /* Scale it down to ns range */
/* This device cannot handle a clock count greater than 32 bits */
if (clocks > 0xffffffff)
@@ -427,22 +443,279 @@ int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, int period,
return -EINVAL;
}
- /* Set and enable the timer */
+ /* Set and enable the timer, reject an attempt to use a wdt as gpt */
spin_lock_irqsave(&gpt->lock, flags);
+ if (as_wdt)
+ gpt->wdt_mode |= MPC52xx_GPT_IS_WDT;
+ else if ((gpt->wdt_mode & MPC52xx_GPT_IS_WDT) != 0) {
+ spin_unlock_irqrestore(&gpt->lock, flags);
+ return -EBUSY;
+ }
out_be32(&gpt->regs->count, prescale << 16 | clocks);
clrsetbits_be32(&gpt->regs->mode, clear, set);
spin_unlock_irqrestore(&gpt->lock, flags);
return 0;
}
+
+/**
+ * mpc52xx_gpt_start_timer - Set and enable the GPT timer
+ * @gpt: Pointer to gpt private data structure
+ * @period: period of timer in ns
+ * @continuous: set to 1 to make timer continuous free running
+ *
+ * An interrupt will be generated every time the timer fires
+ */
+int mpc52xx_gpt_start_timer(struct mpc52xx_gpt_priv *gpt, u64 period,
+ int continuous)
+{
+ return mpc52xx_gpt_do_start(gpt, period, continuous, 0);
+}
EXPORT_SYMBOL(mpc52xx_gpt_start_timer);
-void mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt)
+/**
+ * mpc52xx_gpt_stop_timer - Stop a gpt
+ * @gpt: Pointer to gpt private data structure
+ *
+ * Returns an error if attempting to stop a wdt
+ */
+int mpc52xx_gpt_stop_timer(struct mpc52xx_gpt_priv *gpt)
{
+ unsigned long flags;
+
+ /* reject the operation if the timer is used as watchdog (gpt 0 only) */
+ spin_lock_irqsave(&gpt->lock, flags);
+ if ((gpt->wdt_mode & MPC52xx_GPT_IS_WDT) != 0) {
+ spin_unlock_irqrestore(&gpt->lock, flags);
+ return -EBUSY;
+ }
+
clrbits32(&gpt->regs->mode, MPC52xx_GPT_MODE_COUNTER_ENABLE);
+ spin_unlock_irqrestore(&gpt->lock, flags);
+ return 0;
}
EXPORT_SYMBOL(mpc52xx_gpt_stop_timer);
+/**
+ * mpc52xx_gpt_timer_period - Read the timer period
+ * @gpt: Pointer to gpt private data structure
+ *
+ * Returns the timer period in ns
+ */
+u64 mpc52xx_gpt_timer_period(struct mpc52xx_gpt_priv *gpt)
+{
+ u64 period;
+ u64 prescale;
+ unsigned long flags;
+
+ spin_lock_irqsave(&gpt->lock, flags);
+ period = in_be32(&gpt->regs->count);
+ spin_unlock_irqrestore(&gpt->lock, flags);
+
+ prescale = period >> 16;
+ period &= 0xffff;
+ if (prescale == 0)
+ prescale = 0x10000;
+ period = period * prescale * 1000000000ULL;
+ do_div(period, (u64)gpt->ipb_freq);
+ return period;
+}
+EXPORT_SYMBOL(mpc52xx_gpt_timer_period);
+
+#if defined(CONFIG_MPC5200_WDT)
+/***********************************************************************
+ * Watchdog API for gpt0
+ */
+
+#define WDT_IDENTITY "mpc52xx watchdog on GPT0"
+
+/* wdt_is_active stores wether or not the /dev/watchdog device is opened */
+static unsigned long wdt_is_active;
+
+/* wdt-capable gpt */
+static struct mpc52xx_gpt_priv *mpc52xx_gpt_wdt;
+
+/* low-level wdt functions */
+static inline void mpc52xx_gpt_wdt_ping(struct mpc52xx_gpt_priv *gpt_wdt)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&gpt_wdt->lock, flags);
+ out_8((u8 *) &gpt_wdt->regs->mode, MPC52xx_GPT_MODE_WDT_PING);
+ spin_unlock_irqrestore(&gpt_wdt->lock, flags);
+}
+
+/* wdt misc device api */
+static ssize_t mpc52xx_wdt_write(struct file *file, const char __user *data,
+ size_t len, loff_t *ppos)
+{
+ struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
+ mpc52xx_gpt_wdt_ping(gpt_wdt);
+ return 0;
+}
+
+static struct watchdog_info mpc5200_wdt_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+ .identity = WDT_IDENTITY,
+};
+
+static long mpc52xx_wdt_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
+ int __user *data = (int __user *)arg;
+ int timeout;
+ u64 real_timeout;
+ int ret = 0;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ ret = copy_to_user(data, &mpc5200_wdt_info,
+ sizeof(mpc5200_wdt_info));
+ if (ret)
+ ret = -EFAULT;
+ break;
+
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ ret = put_user(0, data);
+ break;
+
+ case WDIOC_KEEPALIVE:
+ mpc52xx_gpt_wdt_ping(gpt_wdt);
+ break;
+
+ case WDIOC_SETTIMEOUT:
+ ret = get_user(timeout, data);
+ if (ret)
+ break;
+ real_timeout = (u64) timeout * 1000000000ULL;
+ ret = mpc52xx_gpt_do_start(gpt_wdt, real_timeout, 0, 1);
+ if (ret)
+ break;
+ /* fall through and return the timeout */
+
+ case WDIOC_GETTIMEOUT:
+ /* we need to round here as to avoid e.g. the following
+ * situation:
+ * - timeout requested is 1 second;
+ * - real timeout @33MHz is 999997090ns
+ * - the int divide by 10^9 will return 0.
+ */
+ real_timeout =
+ mpc52xx_gpt_timer_period(gpt_wdt) + 500000000ULL;
+ do_div(real_timeout, 1000000000ULL);
+ timeout = (int) real_timeout;
+ ret = put_user(timeout, data);
+ break;
+
+ default:
+ ret = -ENOTTY;
+ }
+ return ret;
+}
+
+static int mpc52xx_wdt_open(struct inode *inode, struct file *file)
+{
+ int ret;
+
+ /* sanity check */
+ if (!mpc52xx_gpt_wdt)
+ return -ENODEV;
+
+ /* /dev/watchdog can only be opened once */
+ if (test_and_set_bit(0, &wdt_is_active))
+ return -EBUSY;
+
+ /* Set and activate the watchdog with 30 seconds timeout */
+ ret = mpc52xx_gpt_do_start(mpc52xx_gpt_wdt, 30ULL * 1000000000ULL,
+ 0, 1);
+ if (ret) {
+ clear_bit(0, &wdt_is_active);
+ return ret;
+ }
+
+ file->private_data = mpc52xx_gpt_wdt;
+ return nonseekable_open(inode, file);
+}
+
+static int mpc52xx_wdt_release(struct inode *inode, struct file *file)
+{
+ /* note: releasing the wdt in NOWAYOUT-mode does not stop it */
+#if !defined(CONFIG_WATCHDOG_NOWAYOUT)
+ struct mpc52xx_gpt_priv *gpt_wdt = file->private_data;
+ unsigned long flags;
+
+ spin_lock_irqsave(&gpt_wdt->lock, flags);
+ clrbits32(&gpt_wdt->regs->mode,
+ MPC52xx_GPT_MODE_COUNTER_ENABLE | MPC52xx_GPT_MODE_WDT_EN);
+ gpt_wdt->wdt_mode &= ~MPC52xx_GPT_IS_WDT;
+ spin_unlock_irqrestore(&gpt_wdt->lock, flags);
+#endif
+ clear_bit(0, &wdt_is_active);
+ return 0;
+}
+
+
+static const struct file_operations mpc52xx_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = mpc52xx_wdt_write,
+ .unlocked_ioctl = mpc52xx_wdt_ioctl,
+ .open = mpc52xx_wdt_open,
+ .release = mpc52xx_wdt_release,
+};
+
+static struct miscdevice mpc52xx_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &mpc52xx_wdt_fops,
+};
+
+static int __devinit mpc52xx_gpt_wdt_init(void)
+{
+ int err;
+
+ /* try to register the watchdog misc device */
+ err = misc_register(&mpc52xx_wdt_miscdev);
+ if (err)
+ pr_err("%s: cannot register watchdog device\n", WDT_IDENTITY);
+ else
+ pr_info("%s: watchdog device registered\n", WDT_IDENTITY);
+ return err;
+}
+
+static int mpc52xx_gpt_wdt_setup(struct mpc52xx_gpt_priv *gpt,
+ const u32 *period)
+{
+ u64 real_timeout;
+
+ /* remember the gpt for the wdt operation */
+ mpc52xx_gpt_wdt = gpt;
+
+ /* configure the wdt if the device tree contained a timeout */
+ if (!period || *period == 0)
+ return 0;
+
+ real_timeout = (u64) *period * 1000000000ULL;
+ if (mpc52xx_gpt_do_start(gpt, real_timeout, 0, 1))
+ dev_warn(gpt->dev, "starting as wdt failed\n");
+ else
+ dev_info(gpt->dev, "watchdog set to %us timeout\n", *period);
+ return 0;
+}
+
+#else
+
+static int __devinit mpc52xx_gpt_wdt_init(void)
+{
+ return 0;
+}
+
+#define mpc52xx_gpt_wdt_setup(x, y) (0)
+
+#endif /* CONFIG_MPC5200_WDT */
+
/* ---------------------------------------------------------------------
* of_platform bus binding code
*/
@@ -473,6 +746,22 @@ static int __devinit mpc52xx_gpt_probe(struct of_device *ofdev,
list_add(&gpt->list, &mpc52xx_gpt_list);
mutex_unlock(&mpc52xx_gpt_list_mutex);
+ /* check if this device could be a watchdog */
+ if (of_get_property(ofdev->node, "fsl,has-wdt", NULL) ||
+ of_get_property(ofdev->node, "has-wdt", NULL)) {
+ const u32 *on_boot_wdt;
+
+ gpt->wdt_mode = MPC52xx_GPT_CAN_WDT;
+ on_boot_wdt = of_get_property(ofdev->node, "fsl,wdt-on-boot",
+ NULL);
+ if (on_boot_wdt) {
+ dev_info(gpt->dev, "used as watchdog\n");
+ gpt->wdt_mode |= MPC52xx_GPT_IS_WDT;
+ } else
+ dev_info(gpt->dev, "can function as watchdog\n");
+ mpc52xx_gpt_wdt_setup(gpt, on_boot_wdt);
+ }
+
return 0;
}
@@ -507,3 +796,4 @@ static int __init mpc52xx_gpt_init(void)
/* Make sure GPIOs and IRQs get set up before anyone tries to use them */
subsys_initcall(mpc52xx_gpt_init);
+device_initcall(mpc52xx_gpt_wdt_init);
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