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Subject[PATCH 4.19 150/321] clocksource/drivers/fttmr010: Fix invalid interrupt register access
Date
From: Tao Ren <taoren@fb.com>

[ Upstream commit 86fe57fc47b17b3528fa5497fc57e158d846c4ea ]

TIMER_INTR_MASK register (Base Address of Timer + 0x38) is not designed
for masking interrupts on ast2500 chips, and it's not even listed in
ast2400 datasheet, so it's not safe to access TIMER_INTR_MASK on aspeed
chips.

Similarly, TIMER_INTR_STATE register (Base Address of Timer + 0x34) is
not interrupt status register on ast2400 and ast2500 chips. Although
there is no side effect to reset the register in fttmr010_common_init(),
it's just misleading to do so.

Besides, "count_down" is renamed to "is_aspeed" in "fttmr010" structure,
and more comments are added so the code is more readble.

Signed-off-by: Tao Ren <taoren@fb.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/clocksource/timer-fttmr010.c | 73 ++++++++++++++++------------
1 file changed, 42 insertions(+), 31 deletions(-)

diff --git a/drivers/clocksource/timer-fttmr010.c b/drivers/clocksource/timer-fttmr010.c
index cf93f6419b514..fadff7915dd9c 100644
--- a/drivers/clocksource/timer-fttmr010.c
+++ b/drivers/clocksource/timer-fttmr010.c
@@ -21,7 +21,7 @@
#include <linux/delay.h>

/*
- * Register definitions for the timers
+ * Register definitions common for all the timer variants.
*/
#define TIMER1_COUNT (0x00)
#define TIMER1_LOAD (0x04)
@@ -36,9 +36,10 @@
#define TIMER3_MATCH1 (0x28)
#define TIMER3_MATCH2 (0x2c)
#define TIMER_CR (0x30)
-#define TIMER_INTR_STATE (0x34)
-#define TIMER_INTR_MASK (0x38)

+/*
+ * Control register (TMC30) bit fields for fttmr010/gemini/moxart timers.
+ */
#define TIMER_1_CR_ENABLE BIT(0)
#define TIMER_1_CR_CLOCK BIT(1)
#define TIMER_1_CR_INT BIT(2)
@@ -53,8 +54,9 @@
#define TIMER_3_CR_UPDOWN BIT(11)

/*
- * The Aspeed AST2400 moves bits around in the control register
- * and lacks bits for setting the timer to count upwards.
+ * Control register (TMC30) bit fields for aspeed ast2400/ast2500 timers.
+ * The aspeed timers move bits around in the control register and lacks
+ * bits for setting the timer to count upwards.
*/
#define TIMER_1_CR_ASPEED_ENABLE BIT(0)
#define TIMER_1_CR_ASPEED_CLOCK BIT(1)
@@ -66,6 +68,18 @@
#define TIMER_3_CR_ASPEED_CLOCK BIT(9)
#define TIMER_3_CR_ASPEED_INT BIT(10)

+/*
+ * Interrupt status/mask register definitions for fttmr010/gemini/moxart
+ * timers.
+ * The registers don't exist and they are not needed on aspeed timers
+ * because:
+ * - aspeed timer overflow interrupt is controlled by bits in Control
+ * Register (TMC30).
+ * - aspeed timers always generate interrupt when either one of the
+ * Match registers equals to Status register.
+ */
+#define TIMER_INTR_STATE (0x34)
+#define TIMER_INTR_MASK (0x38)
#define TIMER_1_INT_MATCH1 BIT(0)
#define TIMER_1_INT_MATCH2 BIT(1)
#define TIMER_1_INT_OVERFLOW BIT(2)
@@ -80,7 +94,7 @@
struct fttmr010 {
void __iomem *base;
unsigned int tick_rate;
- bool count_down;
+ bool is_aspeed;
u32 t1_enable_val;
struct clock_event_device clkevt;
#ifdef CONFIG_ARM
@@ -130,7 +144,7 @@ static int fttmr010_timer_set_next_event(unsigned long cycles,
cr &= ~fttmr010->t1_enable_val;
writel(cr, fttmr010->base + TIMER_CR);

- if (fttmr010->count_down) {
+ if (fttmr010->is_aspeed) {
/*
* ASPEED Timer Controller will load TIMER1_LOAD register
* into TIMER1_COUNT register when the timer is re-enabled.
@@ -175,16 +189,17 @@ static int fttmr010_timer_set_oneshot(struct clock_event_device *evt)

/* Setup counter start from 0 or ~0 */
writel(0, fttmr010->base + TIMER1_COUNT);
- if (fttmr010->count_down)
+ if (fttmr010->is_aspeed) {
writel(~0, fttmr010->base + TIMER1_LOAD);
- else
+ } else {
writel(0, fttmr010->base + TIMER1_LOAD);

- /* Enable interrupt */
- cr = readl(fttmr010->base + TIMER_INTR_MASK);
- cr &= ~(TIMER_1_INT_OVERFLOW | TIMER_1_INT_MATCH2);
- cr |= TIMER_1_INT_MATCH1;
- writel(cr, fttmr010->base + TIMER_INTR_MASK);
+ /* Enable interrupt */
+ cr = readl(fttmr010->base + TIMER_INTR_MASK);
+ cr &= ~(TIMER_1_INT_OVERFLOW | TIMER_1_INT_MATCH2);
+ cr |= TIMER_1_INT_MATCH1;
+ writel(cr, fttmr010->base + TIMER_INTR_MASK);
+ }

return 0;
}
@@ -201,9 +216,8 @@ static int fttmr010_timer_set_periodic(struct clock_event_device *evt)
writel(cr, fttmr010->base + TIMER_CR);

/* Setup timer to fire at 1/HZ intervals. */
- if (fttmr010->count_down) {
+ if (fttmr010->is_aspeed) {
writel(period, fttmr010->base + TIMER1_LOAD);
- writel(0, fttmr010->base + TIMER1_MATCH1);
} else {
cr = 0xffffffff - (period - 1);
writel(cr, fttmr010->base + TIMER1_COUNT);
@@ -281,23 +295,21 @@ static int __init fttmr010_common_init(struct device_node *np, bool is_aspeed)
}

/*
- * The Aspeed AST2400 moves bits around in the control register,
- * otherwise it works the same.
+ * The Aspeed timers move bits around in the control register.
*/
if (is_aspeed) {
fttmr010->t1_enable_val = TIMER_1_CR_ASPEED_ENABLE |
TIMER_1_CR_ASPEED_INT;
- /* Downward not available */
- fttmr010->count_down = true;
+ fttmr010->is_aspeed = true;
} else {
fttmr010->t1_enable_val = TIMER_1_CR_ENABLE | TIMER_1_CR_INT;
- }

- /*
- * Reset the interrupt mask and status
- */
- writel(TIMER_INT_ALL_MASK, fttmr010->base + TIMER_INTR_MASK);
- writel(0, fttmr010->base + TIMER_INTR_STATE);
+ /*
+ * Reset the interrupt mask and status
+ */
+ writel(TIMER_INT_ALL_MASK, fttmr010->base + TIMER_INTR_MASK);
+ writel(0, fttmr010->base + TIMER_INTR_STATE);
+ }

/*
* Enable timer 1 count up, timer 2 count up, except on Aspeed,
@@ -306,9 +318,8 @@ static int __init fttmr010_common_init(struct device_node *np, bool is_aspeed)
if (is_aspeed)
val = TIMER_2_CR_ASPEED_ENABLE;
else {
- val = TIMER_2_CR_ENABLE;
- if (!fttmr010->count_down)
- val |= TIMER_1_CR_UPDOWN | TIMER_2_CR_UPDOWN;
+ val = TIMER_2_CR_ENABLE | TIMER_1_CR_UPDOWN |
+ TIMER_2_CR_UPDOWN;
}
writel(val, fttmr010->base + TIMER_CR);

@@ -321,7 +332,7 @@ static int __init fttmr010_common_init(struct device_node *np, bool is_aspeed)
writel(0, fttmr010->base + TIMER2_MATCH1);
writel(0, fttmr010->base + TIMER2_MATCH2);

- if (fttmr010->count_down) {
+ if (fttmr010->is_aspeed) {
writel(~0, fttmr010->base + TIMER2_LOAD);
clocksource_mmio_init(fttmr010->base + TIMER2_COUNT,
"FTTMR010-TIMER2",
@@ -371,7 +382,7 @@ static int __init fttmr010_common_init(struct device_node *np, bool is_aspeed)

#ifdef CONFIG_ARM
/* Also use this timer for delays */
- if (fttmr010->count_down)
+ if (fttmr010->is_aspeed)
fttmr010->delay_timer.read_current_timer =
fttmr010_read_current_timer_down;
else
--
2.20.1


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