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authorFinn Thain <fthain@telegraphics.com.au>2018-12-01 11:53:10 +1100
committerGeert Uytterhoeven <geert@linux-m68k.org>2019-03-25 10:22:25 +0100
commit19999a8b8782d7f887353753c3c7cb5fca2f3784 (patch)
treebd52382ef3503e75a2875918185073aada40335b /arch/m68k
parent3d744eee38f11cafb0fc332c3081ab1cd07a89f7 (diff)
downloadlinux-19999a8b8782d7f887353753c3c7cb5fca2f3784.tar.bz2
m68k: mvme16x: Handle timer counter overflow
Reading the timer counter races with timer overflow (and the corresponding interrupt). This is resolved by reading the overflow register and taking this value into account. The interrupt handler must clear the overflow register when it eventually executes. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Diffstat (limited to 'arch/m68k')
-rw-r--r--arch/m68k/mvme16x/config.c45
1 files changed, 32 insertions, 13 deletions
diff --git a/arch/m68k/mvme16x/config.c b/arch/m68k/mvme16x/config.c
index 2c109ee2a1a5..9bc2da69f80c 100644
--- a/arch/m68k/mvme16x/config.c
+++ b/arch/m68k/mvme16x/config.c
@@ -115,11 +115,11 @@ static void __init mvme16x_init_IRQ (void)
m68k_setup_user_interrupt(VEC_USER, 192);
}
-#define pcc2chip ((volatile u_char *)0xfff42000)
-#define PccSCCMICR 0x1d
-#define PccSCCTICR 0x1e
-#define PccSCCRICR 0x1f
-#define PccTPIACKR 0x25
+#define PCC2CHIP (0xfff42000)
+#define PCCSCCMICR (PCC2CHIP + 0x1d)
+#define PCCSCCTICR (PCC2CHIP + 0x1e)
+#define PCCSCCRICR (PCC2CHIP + 0x1f)
+#define PCCTPIACKR (PCC2CHIP + 0x25)
#ifdef CONFIG_EARLY_PRINTK
@@ -227,10 +227,10 @@ void mvme16x_cons_write(struct console *co, const char *str, unsigned count)
base_addr[CyIER] = CyTxMpty;
while (1) {
- if (pcc2chip[PccSCCTICR] & 0x20)
+ if (in_8(PCCSCCTICR) & 0x20)
{
/* We have a Tx int. Acknowledge it */
- sink = pcc2chip[PccTPIACKR];
+ sink = in_8(PCCTPIACKR);
if ((base_addr[CyLICR] >> 2) == port) {
if (i == count) {
/* Last char of string is now output */
@@ -359,13 +359,26 @@ static u32 clk_total;
#define PCC_TIMER_CLOCK_FREQ 1000000
#define PCC_TIMER_CYCLES (PCC_TIMER_CLOCK_FREQ / HZ)
+#define PCCTCMP1 (PCC2CHIP + 0x04)
+#define PCCTCNT1 (PCC2CHIP + 0x08)
+#define PCCTOVR1 (PCC2CHIP + 0x17)
+#define PCCTIC1 (PCC2CHIP + 0x1b)
+
+#define PCCTOVR1_TIC_EN 0x01
+#define PCCTOVR1_COC_EN 0x02
+#define PCCTOVR1_OVR_CLR 0x04
+
+#define PCCTIC1_INT_CLR 0x08
+#define PCCTIC1_INT_EN 0x10
+
static irqreturn_t mvme16x_timer_int (int irq, void *dev_id)
{
irq_handler_t timer_routine = dev_id;
unsigned long flags;
local_irq_save(flags);
- *(volatile unsigned char *)0xfff4201b |= 8;
+ out_8(PCCTIC1, in_8(PCCTIC1) | PCCTIC1_INT_CLR);
+ out_8(PCCTOVR1, PCCTOVR1_OVR_CLR);
clk_total += PCC_TIMER_CYCLES;
timer_routine(0, NULL);
local_irq_restore(flags);
@@ -379,10 +392,10 @@ void mvme16x_sched_init (irq_handler_t timer_routine)
int irq;
/* Using PCCchip2 or MC2 chip tick timer 1 */
- *(volatile unsigned long *)0xfff42008 = 0;
- *(volatile unsigned long *)0xfff42004 = PCC_TIMER_CYCLES;
- *(volatile unsigned char *)0xfff42017 |= 3;
- *(volatile unsigned char *)0xfff4201b = 0x16;
+ out_be32(PCCTCNT1, 0);
+ out_be32(PCCTCMP1, PCC_TIMER_CYCLES);
+ out_8(PCCTOVR1, in_8(PCCTOVR1) | PCCTOVR1_TIC_EN | PCCTOVR1_COC_EN);
+ out_8(PCCTIC1, PCCTIC1_INT_EN | 6);
if (request_irq(MVME16x_IRQ_TIMER, mvme16x_timer_int, IRQF_TIMER, "timer",
timer_routine))
panic ("Couldn't register timer int");
@@ -401,10 +414,16 @@ void mvme16x_sched_init (irq_handler_t timer_routine)
static u64 mvme16x_read_clk(struct clocksource *cs)
{
unsigned long flags;
+ u8 overflow, tmp;
u32 ticks;
local_irq_save(flags);
- ticks = *(volatile u32 *)0xfff42008;
+ tmp = in_8(PCCTOVR1) >> 4;
+ ticks = in_be32(PCCTCNT1);
+ overflow = in_8(PCCTOVR1) >> 4;
+ if (overflow != tmp)
+ ticks = in_be32(PCCTCNT1);
+ ticks += overflow * PCC_TIMER_CYCLES;
ticks += clk_total;
local_irq_restore(flags);