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Message-Id: <20170530215139.9983-49-alexandre.belloni@free-electrons.com>
Date: Tue, 30 May 2017 23:51:29 +0200
From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To: Nicolas Ferre <nicolas.ferre@...rochip.com>
Cc: Boris Brezillon <boris.brezillon@...e-electrons.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 48/58] clocksource/drivers: timer-atmel-tcbclksrc: add clockevent device on separate channel
Add an other clockevent device that uses a separate TCB channel when
available.
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
---
drivers/clocksource/timer-atmel-tcbclksrc.c | 177 +++++++++++++++++++++++++++-
1 file changed, 173 insertions(+), 4 deletions(-)
diff --git a/drivers/clocksource/timer-atmel-tcbclksrc.c b/drivers/clocksource/timer-atmel-tcbclksrc.c
index 462b04e9fed8..e117c11b4d1c 100644
--- a/drivers/clocksource/timer-atmel-tcbclksrc.c
+++ b/drivers/clocksource/timer-atmel-tcbclksrc.c
@@ -32,6 +32,167 @@ static struct atmel_tcb_clksrc {
},
};
+static struct tc_clkevt_device {
+ char name[20];
+ struct clock_event_device clkevt;
+ struct regmap *regmap;
+ struct clk *slow_clk;
+ struct clk *clk;
+ int channel;
+ int irq;
+ bool registered;
+} tce = {
+ .clkevt = {
+ .features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT,
+ /*
+ * Should be lower than at91rm9200's system timer
+ * but higher than tc.clkevt.rating
+ */
+ .rating = 140,
+ },
+};
+
+static int tc_clkevt2_shutdown(struct clock_event_device *d)
+{
+ regmap_write(tce.regmap, ATMEL_TC_IDR(tce.channel), 0xff);
+ regmap_write(tce.regmap, ATMEL_TC_CCR(tce.channel),
+ ATMEL_TC_CCR_CLKDIS);
+ if (!clockevent_state_detached(d))
+ clk_disable(tce.clk);
+
+ return 0;
+}
+
+/* For now, we always use the 32K clock ... this optimizes for NO_HZ,
+ * because using one of the divided clocks would usually mean the
+ * tick rate can never be less than several dozen Hz (vs 0.5 Hz).
+ *
+ * A divided clock could be good for high resolution timers, since
+ * 30.5 usec resolution can seem "low".
+ */
+static int tc_clkevt2_set_oneshot(struct clock_event_device *d)
+{
+ if (clockevent_state_oneshot(d) || clockevent_state_periodic(d))
+ tc_clkevt2_shutdown(d);
+
+ clk_enable(tce.clk);
+
+ /* slow clock, count up to RC, then irq and stop */
+ regmap_write(tce.regmap, ATMEL_TC_CMR(tce.channel),
+ ATMEL_TC_CMR_TCLK(4) | ATMEL_TC_CMR_CPCSTOP |
+ ATMEL_TC_CMR_WAVE | ATMEL_TC_CMR_WAVESEL_UPRC);
+ regmap_write(tce.regmap, ATMEL_TC_IER(tce.channel),
+ ATMEL_TC_CPCS);
+
+ return 0;
+}
+
+static int tc_clkevt2_set_periodic(struct clock_event_device *d)
+{
+ if (clockevent_state_oneshot(d) || clockevent_state_periodic(d))
+ tc_clkevt2_shutdown(d);
+
+ /* By not making the gentime core emulate periodic mode on top
+ * of oneshot, we get lower overhead and improved accuracy.
+ */
+ clk_enable(tce.clk);
+
+ /* slow clock, count up to RC, then irq and restart */
+ regmap_write(tce.regmap, ATMEL_TC_CMR(tce.channel),
+ ATMEL_TC_CMR_TCLK(4) | ATMEL_TC_CMR_WAVE |
+ ATMEL_TC_CMR_WAVESEL_UPRC);
+ regmap_write(tce.regmap, ATMEL_TC_RC(tce.channel),
+ (32768 + HZ / 2) / HZ);
+
+ /* Enable clock and interrupts on RC compare */
+ regmap_write(tce.regmap, ATMEL_TC_IER(tce.channel), ATMEL_TC_CPCS);
+ regmap_write(tce.regmap, ATMEL_TC_CCR(tce.channel),
+ ATMEL_TC_CCR_CLKEN | ATMEL_TC_CCR_SWTRG);
+
+ return 0;
+}
+
+static int tc_clkevt2_next_event(unsigned long delta, struct clock_event_device *d)
+{
+ regmap_write(tce.regmap, ATMEL_TC_RC(tce.channel), delta);
+ regmap_write(tce.regmap, ATMEL_TC_CCR(tce.channel),
+ ATMEL_TC_CCR_CLKEN | ATMEL_TC_CCR_SWTRG);
+
+ return 0;
+}
+
+static irqreturn_t tc_clkevt2_irq(int irq, void *handle)
+{
+ unsigned int sr;
+
+ regmap_read(tce.regmap, ATMEL_TC_SR(tce.channel), &sr);
+ if (sr & ATMEL_TC_CPCS) {
+ tce.clkevt.event_handler(&tce.clkevt);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static int __init tc_clkevt_register(struct device_node *node,
+ struct regmap *regmap, int channel,
+ int irq, int bits)
+{
+ int ret;
+
+ tce.regmap = regmap;
+ tce.channel = channel;
+ tce.irq = irq;
+
+ tce.slow_clk = of_clk_get_by_name(node->parent, "slow_clk");
+ if (IS_ERR(tce.slow_clk))
+ return PTR_ERR(tce.slow_clk);
+
+ ret = clk_prepare_enable(tce.slow_clk);
+ if (ret)
+ return ret;
+
+ tce.clk = tcb_clk_get(node, tce.channel);
+ if (IS_ERR(tce.clk)) {
+ ret = PTR_ERR(tce.clk);
+ goto err_slow;
+ }
+
+ snprintf(tce.name, sizeof(tce.name), "%s:%d",
+ kbasename(node->parent->full_name), channel);
+ tce.clkevt.cpumask = cpumask_of(0);
+ tce.clkevt.name = tce.name;
+ tce.clkevt.set_next_event = tc_clkevt2_next_event,
+ tce.clkevt.set_state_shutdown = tc_clkevt2_shutdown,
+ tce.clkevt.set_state_periodic = tc_clkevt2_set_periodic,
+ tce.clkevt.set_state_oneshot = tc_clkevt2_set_oneshot,
+
+ /* try to enable clk to avoid future errors in mode change */
+ ret = clk_prepare_enable(tce.clk);
+ if (ret)
+ goto err_slow;
+ clk_disable(tce.clk);
+
+ clockevents_config_and_register(&tce.clkevt, 32768, 1, bits - 1);
+
+ ret = request_irq(tce.irq, tc_clkevt2_irq, IRQF_TIMER | IRQF_SHARED,
+ tce.clkevt.name, &tce);
+ if (ret)
+ goto err_clk;
+
+ tce.registered = true;
+
+ return 0;
+
+err_clk:
+ clk_unprepare(tce.clk);
+err_slow:
+ clk_disable_unprepare(tce.slow_clk);
+
+ return ret;
+}
+
static u64 tc_get_cycles(struct clocksource *cs)
{
u32 lower, upper, tmp;
@@ -299,7 +460,7 @@ static int __init tcb_clksrc_init(struct device_node *node)
u32 channel;
int bits, irq, err, chan1 = -1;
- if (tc.registered)
+ if (tc.registered && tce.registered)
return -ENODEV;
regmap = syscon_node_to_regmap(node->parent);
@@ -318,12 +479,20 @@ static int __init tcb_clksrc_init(struct device_node *node)
if (irq < 0)
return irq;
+ if (tc.registered)
+ return tc_clkevt_register(node, regmap, channel, irq, bits);
+
if (bits == 16) {
of_property_read_u32_index(node, "reg", 1, &chan1);
if (chan1 == -1) {
- pr_err("%s: clocksource needs two channels\n",
- node->parent->full_name);
- return -EINVAL;
+ if (tce.registered) {
+ pr_err("%s: clocksource needs two channels\n",
+ node->parent->full_name);
+ return -EINVAL;
+ } else {
+ return tc_clkevt_register(node, regmap, channel,
+ irq, bits);
+ }
}
}
--
2.11.0
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