linux-kernel - [PATCH 2/5] clocksource: msc313e: Add support for ssd20xd-based platforms

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Date:   Fri, 26 Nov 2021 21:21:41 +0100
From:   Romain Perier <romain.perier@...il.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Palmer <daniel@...f.com>,
        Romain Perier <romain.perier@...il.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] clocksource: msc313e: Add support for ssd20xd-based platforms

SSD20X family SoCs have an oscillator running at ~432Mhz for timer1 and
timer2, while timer0 is running at 12Mhz. There are no ways to reduce or
divide these clocks in the clktree. However, SSD20X SoCs provide an
internal "timer_divide" register that can act on this input oscillator.
This commit adds support for this register, as timer1 and timer2 are
used as clockevents these will run at 48Mhz.

Signed-off-by: Romain Perier <romain.perier@...il.com>
---
 drivers/clocksource/timer-msc313e.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/clocksource/timer-msc313e.c b/drivers/clocksource/timer-msc313e.c
index 81f161744349..6e7a0ece6601 100644
--- a/drivers/clocksource/timer-msc313e.c
+++ b/drivers/clocksource/timer-msc313e.c
@@ -30,7 +30,9 @@
 #define MSC313E_REG_TIMER_MAX_HIGH	0x0c
 #define MSC313E_REG_COUNTER_LOW		0x10
 #define MSC313E_REG_COUNTER_HIGH	0x14
+#define MSC313E_REG_TIMER_DIVIDE	0x18
 
+#define MSC313E_CLK_DIVIDER		9
 #define TIMER_SYNC_TICKS		3
 
 struct msc313e_delay {
@@ -165,6 +167,12 @@ static int __init msc313e_clkevt_init(struct device_node *np)
 	if (ret)
 		return ret;
 
+	if (of_device_is_compatible(np, "mstar,ssd20xd-timer")) {
+		to->of_clk.rate = clk_get_rate(to->of_clk.clk) / MSC313E_CLK_DIVIDER;
+		to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ);
+		writew(MSC313E_CLK_DIVIDER - 1, timer_of_base(to) + MSC313E_REG_TIMER_DIVIDE);
+	}
+
 	msc313e_clkevt.cpumask = cpu_possible_mask;
 	msc313e_clkevt.irq = to->of_irq.irq;
 	to->clkevt = msc313e_clkevt;
@@ -226,3 +234,4 @@ static int __init msc313e_timer_init(struct device_node *np)
 }
 
 TIMER_OF_DECLARE(msc313, "mstar,msc313e-timer", msc313e_timer_init);
+TIMER_OF_DECLARE(ssd20xd, "mstar,ssd20xd-timer", msc313e_timer_init);
-- 
2.33.0