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clocksource/drivers/fttmr010: Fix invalid interrupt register access
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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>
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Tao Ren authored and Daniel Lezcano committed Dec 18, 2018
1 parent 5eb73c8 commit 86fe57f
Showing 1 changed file with 42 additions and 31 deletions.
73 changes: 42 additions & 31 deletions drivers/clocksource/timer-fttmr010.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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)
Expand All @@ -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)
Expand All @@ -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)
Expand All @@ -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
Expand Down Expand Up @@ -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.
Expand Down Expand Up @@ -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;
}
Expand All @@ -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);
Expand Down Expand Up @@ -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,
Expand All @@ -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);

Expand All @@ -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",
Expand Down Expand Up @@ -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
Expand Down

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