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clocksource/drivers/dw_apb: Add reset control 

Add code to retrieve the reset property from the dw-apb timers and if
the property is available, the safe operation is to assert the timer
into reset, and followed by a deassert of the timer reset (brings the
timer out of reset).

This patch is needed for systems where the bootloader has left the timer
not used in reset.

 - Trivial conflict with commit a74bd1ad7a:
    "Convert to using %pOFn instead of device_node.name"

Reported-by: Marek Vasut <marex@denx.de>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Dinh Nguyen 2018-09-17 09:52:14 -05:00 committed by Daniel Lezcano
parent 9414229c9c
commit 1f174a1a2c
1 changed files with 12 additions and 0 deletions
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12
drivers/clocksource/dw_apb_timer_of.c
View File

@ -22,6 +22,7 @@
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/clk.h>
#include <linux/reset.h>
#include <linux/sched_clock.h>
static void __init timer_get_base_and_rate(struct device_node *np,
@ -29,12 +30,23 @@ static void __init timer_get_base_and_rate(struct device_node *np,
{
struct clk *timer_clk;
struct clk *pclk;
struct reset_control *rstc;
*base = of_iomap(np, 0);
if (!*base)
panic("Unable to map regs for %pOFn", np);
/*
* Reset the timer if the reset control is available, wiping
* out the state the firmware may have left it
*/
rstc = of_reset_control_get(np, NULL);
if (!IS_ERR(rstc)) {
reset_control_assert(rstc);
reset_control_deassert(rstc);
}
/*
* Not all implementations use a periphal clock, so don't panic
* if it's not present