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[WATCHDOG] mv64x60_wdt: Rework the timeout register manipulation 

Consolidate the timeout config register modification into a single
function.  Also, use the enabled flag in the config register to
determine whether the timer is enabled instead of a separately
maintained flag, MV64x60_WDOG_FLAG_ENABLED.

Add spinlock protection around enabling/disabling the watchdog timer.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Dale Farnsworth 2007-07-24 11:31:25 -07:00 committed by Wim Van Sebroeck
parent 2422df5e26
commit f18699940c
1 changed files with 55 additions and 37 deletions
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92
drivers/char/watchdog/mv64x60_wdt.c
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@ -29,75 +29,95 @@
#define MV64x60_WDT_WDC_OFFSET 0
/* MV64x60 WDC (config) register access definitions */
#define MV64x60_WDC_CTL1_MASK (3 << 24)
#define MV64x60_WDC_CTL1(val) ((val & 3) << 24)
#define MV64x60_WDC_CTL2_MASK (3 << 26)
#define MV64x60_WDC_CTL2(val) ((val & 3) << 26)
/*
* The watchdog configuration register contains a pair of 2-bit fields,
* 1. a reload field, bits 27-26, which triggers a reload of
* the countdown register, and
* 2. an enable field, bits 25-24, which toggles between
* enabling and disabling the watchdog timer.
* Bit 31 is a read-only field which indicates whether the
* watchdog timer is currently enabled.
*
* The low 24 bits contain the timer reload value.
*/
#define MV64x60_WDC_ENABLE_SHIFT 24
#define MV64x60_WDC_SERVICE_SHIFT 26
#define MV64x60_WDC_ENABLED_SHIFT 31
#define MV64x60_WDC_ENABLED_TRUE 1
#define MV64x60_WDC_ENABLED_FALSE 0
/* Flags bits */
#define MV64x60_WDOG_FLAG_OPENED 0
#define MV64x60_WDOG_FLAG_ENABLED 1
static unsigned long wdt_flags;
static int wdt_status;
static void __iomem *mv64x60_wdt_regs;
static int mv64x60_wdt_timeout;
static int mv64x60_wdt_count;
static unsigned int bus_clk;
static char expect_close;
static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static void mv64x60_wdt_reg_write(u32 val)
static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
{
/* Allow write only to CTL1 / CTL2 fields, retaining values in
* other fields.
*/
u32 data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
data &= ~(MV64x60_WDC_CTL1_MASK | MV64x60_WDC_CTL2_MASK);
data |= val;
writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
u32 data;
u32 enabled;
int ret = 0;
spin_lock(&mv64x60_wdt_spinlock);
data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
/* only toggle the requested field if enabled state matches predicate */
if ((enabled ^ enabled_predicate) == 0) {
/* We write a 1, then a 2 -- to the appropriate field */
data = (1 << field_shift) | mv64x60_wdt_count;
writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
data = (2 << field_shift) | mv64x60_wdt_count;
writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
ret = 1;
}
spin_unlock(&mv64x60_wdt_spinlock);
return ret;
}
static void mv64x60_wdt_service(void)
{
/* Write 01 followed by 10 to CTL2 */
mv64x60_wdt_reg_write(MV64x60_WDC_CTL2(0x01));
mv64x60_wdt_reg_write(MV64x60_WDC_CTL2(0x02));
}
static void mv64x60_wdt_handler_disable(void)
{
if (test_and_clear_bit(MV64x60_WDOG_FLAG_ENABLED, &wdt_flags)) {
/* Write 01 followed by 10 to CTL1 */
mv64x60_wdt_reg_write(MV64x60_WDC_CTL1(0x01));
mv64x60_wdt_reg_write(MV64x60_WDC_CTL1(0x02));
printk(KERN_NOTICE "mv64x60_wdt: watchdog deactivated\n");
}
mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
MV64x60_WDC_SERVICE_SHIFT);
}
static void mv64x60_wdt_handler_enable(void)
{
if (!test_and_set_bit(MV64x60_WDOG_FLAG_ENABLED, &wdt_flags)) {
/* Write 01 followed by 10 to CTL1 */
mv64x60_wdt_reg_write(MV64x60_WDC_CTL1(0x01));
mv64x60_wdt_reg_write(MV64x60_WDC_CTL1(0x02));
if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
MV64x60_WDC_ENABLE_SHIFT)) {
mv64x60_wdt_service();
printk(KERN_NOTICE "mv64x60_wdt: watchdog activated\n");
}
}
static void mv64x60_wdt_set_timeout(int timeout)
static void mv64x60_wdt_handler_disable(void)
{
if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
MV64x60_WDC_ENABLE_SHIFT))
printk(KERN_NOTICE "mv64x60_wdt: watchdog deactivated\n");
}
static void mv64x60_wdt_set_timeout(unsigned int timeout)
{
/* maximum bus cycle count is 0xFFFFFFFF */
if (timeout > 0xFFFFFFFF / bus_clk)
timeout = 0xFFFFFFFF / bus_clk;
mv64x60_wdt_count = timeout * bus_clk >> 8;
mv64x60_wdt_timeout = timeout;
writel((timeout * bus_clk) >> 8,
mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
mv64x60_wdt_service();
}
static int mv64x60_wdt_open(struct inode *inode, struct file *file)
@ -108,7 +128,6 @@ static int mv64x60_wdt_open(struct inode *inode, struct file *file)
if (nowayout)
__module_get(THIS_MODULE);
mv64x60_wdt_service();
mv64x60_wdt_handler_enable();
return nonseekable_open(inode, file);
@ -270,7 +289,6 @@ static int __devexit mv64x60_wdt_remove(struct platform_device *dev)
{
misc_deregister(&mv64x60_wdt_miscdev);
mv64x60_wdt_service();
mv64x60_wdt_handler_disable();
iounmap(mv64x60_wdt_regs);