linux-kernel - [tip: timers/core] clocksource/drivers/msc313e: Add support for ssd20xd-based platforms

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Date:   Mon, 10 Jan 2022 12:59:51 -0000
From:   "tip-bot2 for Romain Perier" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Romain Perier <romain.perier@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: timers/core] clocksource/drivers/msc313e: Add support for
 ssd20xd-based platforms

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     e64da64f410cf4f9697e25ab76cdfc679f4fb6db
Gitweb:        https://git.kernel.org/tip/e64da64f410cf4f9697e25ab76cdfc679f4fb6db
Author:        Romain Perier <romain.perier@...il.com>
AuthorDate:    Fri, 17 Dec 2021 20:57:23 +01:00
Committer:     Daniel Lezcano <daniel.lezcano@...aro.org>
CommitterDate: Mon, 20 Dec 2021 13:28:39 +01:00

clocksource/drivers/msc313e: Add support for ssd20xd-based platforms

On SSD20X family SoCs the timers are connected to a 432MHz clock instead
of 12MHz that all the previous chips used. There is no way to reduce or
divide these clocks in the clktree yet as we do not know exactly where
the 432MHz clock comes from but it is enabled at boot.

The SSD20X timers have an input clock divider within the timer itself
to configure the frequency. timer0 is preconfigured at power up to run
at 12MHz so it is backwards compatible and doesn't need special handling
right now. timer1 and timer2 run at 432Mhz at power up so are not
backward compatible.

This commit adds support for the input clock divider register and sets
timer1 and timer2 to run at 48Mhz for clockevents.

Signed-off-by: Romain Perier <romain.perier@...il.com>
Link: https://lore.kernel.org/r/20211217195727.8955-3-romain.perier@gmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 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 154e734..54c54ca 100644
--- a/drivers/clocksource/timer-msc313e.c
+++ b/drivers/clocksource/timer-msc313e.c
@@ -33,7 +33,9 @@
 #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
 
 #ifdef CONFIG_ARM
@@ -179,6 +181,12 @@ static int __init msc313e_clkevt_init(struct device_node *np)
 	if (ret)
 		return ret;
 
+	if (of_device_is_compatible(np, "sstar,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;
@@ -242,3 +250,4 @@ static int __init msc313e_timer_init(struct device_node *np)
 }
 
 TIMER_OF_DECLARE(msc313, "mstar,msc313e-timer", msc313e_timer_init);
+TIMER_OF_DECLARE(ssd20xd, "sstar,ssd20xd-timer", msc313e_timer_init);