[PATCH v2 3/9] clocksource/drivers/tcb_clksrc: Use tcb as sched_clock

Alexandre Belloni
2019-04-15T15:09:58Z

Now that the driver is registered early enough, use the TCB as the
sched_clock which is much more accurate than the jiffies implementation.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
drivers/clocksource/tcb_clksrc.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index bf68504da94a..9de8c10ab546 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -11,6 +11,7 @@
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
#include <linux/syscore_ops.h>
#include <soc/at91/atmel_tcb.h>

@@ -114,6 +115,16 @@ static struct clocksource clksrc = {
.resume = tc_clksrc_resume,
};

+static u64 notrace tc_sched_clock_read(void)
+{
+ return tc_get_cycles(&clksrc);
+}
+
+static u64 notrace tc_sched_clock_read32(void)
+{
+ return tc_get_cycles32(&clksrc);
+}
+
#ifdef CONFIG_GENERIC_CLOCKEVENTS

struct tc_clkevt_device {
@@ -335,6 +346,7 @@ static int __init tcb_clksrc_init(struct device_node *node)
struct atmel_tc tc;
struct clk *t0_clk;
const struct of_device_id *match;
+ u64 (*tc_sched_clock)(void);
u32 rate, divided_rate = 0;
int best_divisor_idx = -1;
int clk32k_divisor_idx = -1;
@@ -419,6 +431,7 @@ static int __init tcb_clksrc_init(struct device_node *node)
clksrc.read = tc_get_cycles32;
/* setup ony channel 0 */
tcb_setup_single_chan(&tc, best_divisor_idx);
+ tc_sched_clock = tc_sched_clock_read32;
} else {
/* we have three clocks no matter what the
* underlying platform supports.
@@ -430,6 +443,7 @@ static int __init tcb_clksrc_init(struct device_node *node)
}
/* setup both channel 0 & 1 */
tcb_setup_dual_chan(&tc, best_divisor_idx);
+ tc_sched_clock = tc_sched_clock_read;
}

/* and away we go! */
@@ -442,6 +456,8 @@ static int __init tcb_clksrc_init(struct device_node *node)
if (ret)
goto err_unregister_clksrc;

+ sched_clock_register(tc_sched_clock, 32, divided_rate);
+
return 0;