diff options
Diffstat (limited to 'src/arch/x86/interface/pcbios/rtc_entropy.c')
| -rw-r--r-- | src/arch/x86/interface/pcbios/rtc_entropy.c | 33 |
1 files changed, 25 insertions, 8 deletions
diff --git a/src/arch/x86/interface/pcbios/rtc_entropy.c b/src/arch/x86/interface/pcbios/rtc_entropy.c index 8f47ff6b8..7c98019b6 100644 --- a/src/arch/x86/interface/pcbios/rtc_entropy.c +++ b/src/arch/x86/interface/pcbios/rtc_entropy.c @@ -53,6 +53,12 @@ extern void rtc_isr ( void ); /** Previous RTC interrupt handler */ static struct segoff rtc_old_handler; +/** Previous RTC interrupt enabled state */ +static uint8_t rtc_irq_enabled; + +/** Previous RTC periodic interrupt enabled state */ +static uint8_t rtc_int_enabled; + /** Flag set by RTC interrupt handler */ extern volatile uint8_t __text16 ( rtc_flag ); #define rtc_flag __use_text16 ( rtc_flag ) @@ -107,8 +113,9 @@ static void rtc_unhook_isr ( void ) { /** * Enable RTC interrupts * + * @ret enabled Periodic interrupt was previously enabled */ -static void rtc_enable_int ( void ) { +static int rtc_enable_int ( void ) { uint8_t status_b; /* Clear any stale pending interrupts via status register C */ @@ -124,6 +131,9 @@ static void rtc_enable_int ( void ) { /* Re-enable NMI and reset to default address */ outb ( CMOS_DEFAULT_ADDRESS, CMOS_ADDRESS ); inb ( CMOS_DATA ); /* Discard; may be needed on some platforms */ + + /* Return previous state */ + return ( status_b & RTC_STATUS_B_PIE ); } /** @@ -198,8 +208,11 @@ static int rtc_entropy_enable ( void ) { /* Hook ISR and enable RTC interrupts */ rtc_hook_isr(); - enable_irq ( RTC_IRQ ); - rtc_enable_int(); + rtc_irq_enabled = enable_irq ( RTC_IRQ ); + rtc_int_enabled = rtc_enable_int(); + DBGC ( &rtc_flag, "RTC had IRQ%d %sabled, interrupt %sabled\n", + RTC_IRQ, ( rtc_irq_enabled ? "en" : "dis" ), + ( rtc_int_enabled ? "en" : "dis" ) ); /* Check that RTC interrupts are working */ if ( ( rc = rtc_entropy_check() ) != 0 ) @@ -223,8 +236,10 @@ static int rtc_entropy_enable ( void ) { return 0; err_check: - rtc_disable_int(); - disable_irq ( RTC_IRQ ); + if ( ! rtc_int_enabled ) + rtc_disable_int(); + if ( ! rtc_irq_enabled ) + disable_irq ( RTC_IRQ ); rtc_unhook_isr(); err_no_tsc: return rc; @@ -236,9 +251,11 @@ static int rtc_entropy_enable ( void ) { */ static void rtc_entropy_disable ( void ) { - /* Disable RTC interrupts and unhook ISR */ - rtc_disable_int(); - disable_irq ( RTC_IRQ ); + /* Restore RTC interrupt state and unhook ISR */ + if ( ! rtc_int_enabled ) + rtc_disable_int(); + if ( ! rtc_irq_enabled ) + disable_irq ( RTC_IRQ ); rtc_unhook_isr(); } |