[PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[Alexandre Belloni]

Hi,

This series gets back on the TCB drivers rework. It introduces a new driver to
handle the clocksource and clockevent devices.

As a reminder, this is necessary because:
 - the current tcb_clksrc driver is probed too late to be able to be used at
   boot and we now have SoCs that don't have a PIT. They currently are not able
   to boot a mainline kernel.
 - using the PIT doesn't work well with preempt-rt because its interrupt is
   shared (in particular with the UART and their interrupt flags are
   incompatible)
 - the current solution is wasting some TCB channels

The plan is to get this driver upstream, then convert the TCB PWM driver to be
able to get rid of the tcb_clksrc driver along with atmel_tclib.

Changes in v4:
 - rebased on top of v4.17-rc1
 - fixed an issue when setting max_delta for clockevents_config_and_register

Alexandre Belloni (6):
  ARM: at91: add TCB registers definitions
  clocksource/drivers: Add a new driver for the Atmel ARM TC blocks
  clocksource/drivers: atmel-pit: make option silent
  ARM: at91: Implement clocksource selection
  ARM: configs: at91: use new TCB timer driver
  ARM: configs: at91: unselect PIT

 arch/arm/configs/at91_dt_defconfig    |   2 +-
 arch/arm/configs/sama5_defconfig      |   2 +-
 arch/arm/mach-at91/Kconfig            |  25 ++
 drivers/clocksource/Kconfig           |  13 +-
 drivers/clocksource/Makefile          |   3 +-
 drivers/clocksource/timer-atmel-tcb.c | 608 ++++++++++++++++++++++++++
 include/soc/at91/atmel_tcb.h          | 216 +++++++++
 7 files changed, 865 insertions(+), 4 deletions(-)
 create mode 100644 drivers/clocksource/timer-atmel-tcb.c
 create mode 100644 include/soc/at91/atmel_tcb.h

-- 
2.17.0

[PATCH v4 1/6] ARM: at91: add TCB registers definitions

[Alexandre Belloni]

Add registers and bits definitions for the timer counter blocks found on
Atmel ARM SoCs.

Tested-by: Alexander Dahl <ada@thorsis.com>
Tested-by: Andras Szemzo <szemzo.andras@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 include/soc/at91/atmel_tcb.h | 216 +++++++++++++++++++++++++++++++++++
 1 file changed, 216 insertions(+)
 create mode 100644 include/soc/at91/atmel_tcb.h

diff --git a/include/soc/at91/atmel_tcb.h b/include/soc/at91/atmel_tcb.h
new file mode 100644
index 000000000000..d263ea677225
--- /dev/null
+++ b/include/soc/at91/atmel_tcb.h
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2018 Microchip */
+
+#ifndef __SOC_ATMEL_TCB_H
+#define __SOC_ATMEL_TCB_H
+
+/* Channel registers */
+#define ATMEL_TC_COFFS(c)		((c) * 0x40)
+#define ATMEL_TC_CCR(c)			ATMEL_TC_COFFS(c)
+#define ATMEL_TC_CMR(c)			(ATMEL_TC_COFFS(c) + 0x4)
+#define ATMEL_TC_SMMR(c)		(ATMEL_TC_COFFS(c) + 0x8)
+#define ATMEL_TC_RAB(c)			(ATMEL_TC_COFFS(c) + 0xc)
+#define ATMEL_TC_CV(c)			(ATMEL_TC_COFFS(c) + 0x10)
+#define ATMEL_TC_RA(c)			(ATMEL_TC_COFFS(c) + 0x14)
+#define ATMEL_TC_RB(c)			(ATMEL_TC_COFFS(c) + 0x18)
+#define ATMEL_TC_RC(c)			(ATMEL_TC_COFFS(c) + 0x1c)
+#define ATMEL_TC_SR(c)			(ATMEL_TC_COFFS(c) + 0x20)
+#define ATMEL_TC_IER(c)			(ATMEL_TC_COFFS(c) + 0x24)
+#define ATMEL_TC_IDR(c)			(ATMEL_TC_COFFS(c) + 0x28)
+#define ATMEL_TC_IMR(c)			(ATMEL_TC_COFFS(c) + 0x2c)
+#define ATMEL_TC_EMR(c)			(ATMEL_TC_COFFS(c) + 0x30)
+
+/* Block registers */
+#define ATMEL_TC_BCR			0xc0
+#define ATMEL_TC_BMR			0xc4
+#define ATMEL_TC_QIER			0xc8
+#define ATMEL_TC_QIDR			0xcc
+#define ATMEL_TC_QIMR			0xd0
+#define ATMEL_TC_QISR			0xd4
+#define ATMEL_TC_FMR			0xd8
+#define ATMEL_TC_WPMR			0xe4
+
+/* CCR fields */
+#define ATMEL_TC_CCR_CLKEN		BIT(0)
+#define ATMEL_TC_CCR_CLKDIS		BIT(1)
+#define ATMEL_TC_CCR_SWTRG		BIT(2)
+
+/* Common CMR fields */
+#define ATMEL_TC_CMR_TCLKS_MSK		GENMASK(2, 0)
+#define ATMEL_TC_CMR_TCLK(x)		(x)
+#define ATMEL_TC_CMR_XC(x)		((x) + 5)
+#define ATMEL_TC_CMR_CLKI		BIT(3)
+#define ATMEL_TC_CMR_BURST_MSK		GENMASK(5, 4)
+#define ATMEL_TC_CMR_BURST_XC(x)	(((x) + 1) << 4)
+#define ATMEL_TC_CMR_WAVE		BIT(15)
+
+/* Capture mode CMR fields */
+#define ATMEL_TC_CMR_LDBSTOP		BIT(6)
+#define ATMEL_TC_CMR_LDBDIS		BIT(7)
+#define ATMEL_TC_CMR_ETRGEDG_MSK	GENMASK(9, 8)
+#define ATMEL_TC_CMR_ETRGEDG_NONE	(0 << 8)
+#define ATMEL_TC_CMR_ETRGEDG_RISING	(1 << 8)
+#define ATMEL_TC_CMR_ETRGEDG_FALLING	(2 << 8)
+#define ATMEL_TC_CMR_ETRGEDG_BOTH	(3 << 8)
+#define ATMEL_TC_CMR_ABETRG		BIT(10)
+#define ATMEL_TC_CMR_CPCTRG		BIT(14)
+#define ATMEL_TC_CMR_LDRA_MSK		GENMASK(17, 16)
+#define ATMEL_TC_CMR_LDRA_NONE		(0 << 16)
+#define ATMEL_TC_CMR_LDRA_RISING	(1 << 16)
+#define ATMEL_TC_CMR_LDRA_FALLING	(2 << 16)
+#define ATMEL_TC_CMR_LDRA_BOTH		(3 << 16)
+#define ATMEL_TC_CMR_LDRB_MSK		GENMASK(19, 18)
+#define ATMEL_TC_CMR_LDRB_NONE		(0 << 18)
+#define ATMEL_TC_CMR_LDRB_RISING	(1 << 18)
+#define ATMEL_TC_CMR_LDRB_FALLING	(2 << 18)
+#define ATMEL_TC_CMR_LDRB_BOTH		(3 << 18)
+#define ATMEL_TC_CMR_SBSMPLR_MSK	GENMASK(22, 20)
+#define ATMEL_TC_CMR_SBSMPLR(x)		((x) << 20)
+
+/* Waveform mode CMR fields */
+#define ATMEL_TC_CMR_CPCSTOP		BIT(6)
+#define ATMEL_TC_CMR_CPCDIS		BIT(7)
+#define ATMEL_TC_CMR_EEVTEDG_MSK	GENMASK(9, 8)
+#define ATMEL_TC_CMR_EEVTEDG_NONE	(0 << 8)
+#define ATMEL_TC_CMR_EEVTEDG_RISING	(1 << 8)
+#define ATMEL_TC_CMR_EEVTEDG_FALLING	(2 << 8)
+#define ATMEL_TC_CMR_EEVTEDG_BOTH	(3 << 8)
+#define ATMEL_TC_CMR_EEVT_MSK		GENMASK(11, 10)
+#define ATMEL_TC_CMR_EEVT_XC(x)		(((x) + 1) << 10)
+#define ATMEL_TC_CMR_ENETRG		BIT(12)
+#define ATMEL_TC_CMR_WAVESEL_MSK	GENMASK(14, 13)
+#define ATMEL_TC_CMR_WAVESEL_UP		(0 << 13)
+#define ATMEL_TC_CMR_WAVESEL_UPDOWN	(1 << 13)
+#define ATMEL_TC_CMR_WAVESEL_UPRC	(2 << 13)
+#define ATMEL_TC_CMR_WAVESEL_UPDOWNRC	(3 << 13)
+#define ATMEL_TC_CMR_ACPA_MSK		GENMASK(17, 16)
+#define ATMEL_TC_CMR_ACPA(a)		(ATMEL_TC_CMR_ACTION_##a << 16)
+#define ATMEL_TC_CMR_ACPC_MSK		GENMASK(19, 18)
+#define ATMEL_TC_CMR_ACPC(a)		(ATMEL_TC_CMR_ACTION_##a << 18)
+#define ATMEL_TC_CMR_AEEVT_MSK		GENMASK(21, 20)
+#define ATMEL_TC_CMR_AEEVT(a)		(ATMEL_TC_CMR_ACTION_##a << 20)
+#define ATMEL_TC_CMR_ASWTRG_MSK		GENMASK(23, 22)
+#define ATMEL_TC_CMR_ASWTRG(a)		(ATMEL_TC_CMR_ACTION_##a << 22)
+#define ATMEL_TC_CMR_BCPB_MSK		GENMASK(25, 24)
+#define ATMEL_TC_CMR_BCPB(a)		(ATMEL_TC_CMR_ACTION_##a << 24)
+#define ATMEL_TC_CMR_BCPC_MSK		GENMASK(27, 26)
+#define ATMEL_TC_CMR_BCPC(a)		(ATMEL_TC_CMR_ACTION_##a << 26)
+#define ATMEL_TC_CMR_BEEVT_MSK		GENMASK(29, 28)
+#define ATMEL_TC_CMR_BEEVT(a)		(ATMEL_TC_CMR_ACTION_##a << 28)
+#define ATMEL_TC_CMR_BSWTRG_MSK		GENMASK(31, 30)
+#define ATMEL_TC_CMR_BSWTRG(a)		(ATMEL_TC_CMR_ACTION_##a << 30)
+#define ATMEL_TC_CMR_ACTION_NONE	0
+#define ATMEL_TC_CMR_ACTION_SET		1
+#define ATMEL_TC_CMR_ACTION_CLEAR	2
+#define ATMEL_TC_CMR_ACTION_TOGGLE	3
+
+/* SMMR fields */
+#define ATMEL_TC_SMMR_GCEN		BIT(0)
+#define ATMEL_TC_SMMR_DOWN		BIT(1)
+
+/* SR/IER/IDR/IMR fields */
+#define ATMEL_TC_COVFS			BIT(0)
+#define ATMEL_TC_LOVRS			BIT(1)
+#define ATMEL_TC_CPAS			BIT(2)
+#define ATMEL_TC_CPBS			BIT(3)
+#define ATMEL_TC_CPCS			BIT(4)
+#define ATMEL_TC_LDRAS			BIT(5)
+#define ATMEL_TC_LDRBS			BIT(6)
+#define ATMEL_TC_ETRGS			BIT(7)
+#define ATMEL_TC_CLKSTA			BIT(16)
+#define ATMEL_TC_MTIOA			BIT(17)
+#define ATMEL_TC_MTIOB			BIT(18)
+
+/* EMR fields */
+#define ATMEL_TC_EMR_TRIGSRCA_MSK	GENMASK(1, 0)
+#define ATMEL_TC_EMR_TRIGSRCA_TIOA	0
+#define ATMEL_TC_EMR_TRIGSRCA_PWMX	1
+#define ATMEL_TC_EMR_TRIGSRCB_MSK	GENMASK(5, 4)
+#define ATMEL_TC_EMR_TRIGSRCB_TIOB	(0 << 4)
+#define ATMEL_TC_EMR_TRIGSRCB_PWM	(1 << 4)
+#define ATMEL_TC_EMR_NOCLKDIV		BIT(8)
+
+/* BCR fields */
+#define ATMEL_TC_BCR_SYNC		BIT(0)
+
+/* BMR fields */
+#define ATMEL_TC_BMR_TCXC_MSK(c)	GENMASK(((c) * 2) + 1, (c) * 2)
+#define ATMEL_TC_BMR_TCXC(x, c)		((x) << (2 * (c)))
+#define ATMEL_TC_BMR_QDEN		BIT(8)
+#define ATMEL_TC_BMR_POSEN		BIT(9)
+#define ATMEL_TC_BMR_SPEEDEN		BIT(10)
+#define ATMEL_TC_BMR_QDTRANS		BIT(11)
+#define ATMEL_TC_BMR_EDGPHA		BIT(12)
+#define ATMEL_TC_BMR_INVA		BIT(13)
+#define ATMEL_TC_BMR_INVB		BIT(14)
+#define ATMEL_TC_BMR_INVIDX		BIT(15)
+#define ATMEL_TC_BMR_SWAP		BIT(16)
+#define ATMEL_TC_BMR_IDXPHB		BIT(17)
+#define ATMEL_TC_BMR_AUTOC		BIT(18)
+#define ATMEL_TC_MAXFILT_MSK		GENMASK(25, 20)
+#define ATMEL_TC_MAXFILT(x)		(((x) - 1) << 20)
+#define ATMEL_TC_MAXCMP_MSK		GENMASK(29, 26)
+#define ATMEL_TC_MAXCMP(x)		((x) << 26)
+
+/* QEDC fields */
+#define ATMEL_TC_QEDC_IDX		BIT(0)
+#define ATMEL_TC_QEDC_DIRCHG		BIT(1)
+#define ATMEL_TC_QEDC_QERR		BIT(2)
+#define ATMEL_TC_QEDC_MPE		BIT(3)
+#define ATMEL_TC_QEDC_DIR		BIT(8)
+
+/* FMR fields */
+#define ATMEL_TC_FMR_ENCF(x)		BIT(x)
+
+/* WPMR fields */
+#define ATMEL_TC_WPMR_WPKEY		(0x54494d << 8)
+#define ATMEL_TC_WPMR_WPEN		BIT(0)
+
+static inline struct clk *tcb_clk_get(struct device_node *node, int channel)
+{
+	struct clk *clk;
+	char clk_name[] = "t0_clk";
+
+	clk_name[1] += channel;
+	clk = of_clk_get_by_name(node->parent, clk_name);
+	if (!IS_ERR(clk))
+		return clk;
+
+	return of_clk_get_by_name(node->parent, "t0_clk");
+}
+
+static inline int tcb_irq_get(struct device_node *node, int channel)
+{
+	int irq;
+
+	irq = of_irq_get(node->parent, channel);
+	if (irq > 0)
+		return irq;
+
+	return of_irq_get(node->parent, 0);
+}
+
+static const u8 atmel_tc_divisors[5] = { 2, 8, 32, 128, 0, };
+
+struct atmel_tcb_info {
+	int bits;
+};
+
+static const struct atmel_tcb_info atmel_tcb_infos[] = {
+	{ .bits = 16 },
+	{ .bits = 32 },
+};
+
+static const struct of_device_id atmel_tcb_dt_ids[] = {
+	{
+		.compatible = "atmel,at91rm9200-tcb",
+		.data = &atmel_tcb_infos[0],
+	}, {
+		.compatible = "atmel,at91sam9x5-tcb",
+		.data = &atmel_tcb_infos[1],
+	}, {
+		/* sentinel */
+	}
+};
+
+#endif /* __SOC_ATMEL_TCB_H */
-- 
2.17.0

[PATCH v4 2/6] clocksource/drivers: Add a new driver for the Atmel ARM TC blocks

[Alexandre Belloni]

Add a driver for the Atmel Timer Counter Blocks. This driver provides a
clocksource and two clockevent devices.

One of the clockevent device is linked to the clocksource counter and so it
will run at the same frequency. This will be used when there is only on TCB
channel available for timers.

The other clockevent device runs on a separate TCB channel when available.

This driver uses regmap and syscon to be able to probe early in the boot
and avoid having to switch on the TCB clocksource later. Using regmap also
means that unused TCB channels may be used by other drivers (PWM for
example). read/writel are still used to access channel specific registers
to avoid the performance impact of regmap (mainly locking).

Tested-by: Alexander Dahl <ada@thorsis.com>
Tested-by: Andras Szemzo <szemzo.andras@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/clocksource/Kconfig           |   8 +
 drivers/clocksource/Makefile          |   3 +-
 drivers/clocksource/timer-atmel-tcb.c | 608 ++++++++++++++++++++++++++
 3 files changed, 618 insertions(+), 1 deletion(-)
 create mode 100644 drivers/clocksource/timer-atmel-tcb.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 9ee2888275c1..540892273a8d 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -395,6 +395,14 @@ config ATMEL_ST
 	help
 	  Support for the Atmel ST timer.
 
+config ATMEL_ARM_TCB_CLKSRC
+	bool "Microchip ARM TC Block" if COMPILE_TEST
+	select REGMAP_MMIO
+	depends on GENERIC_CLOCKEVENTS
+	help
+	  This enables build of clocksource and clockevent driver for
+	  the integrated Timer Counter Blocks in Microchip ARM SoCs.
+
 config CLKSRC_EXYNOS_MCT
 	bool "Exynos multi core timer driver" if COMPILE_TEST
 	depends on ARM || ARM64
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index e8e76dfef00b..a8e9d40c68d2 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -3,7 +3,8 @@ obj-$(CONFIG_TIMER_OF)		+= timer-of.o
 obj-$(CONFIG_TIMER_PROBE)	+= timer-probe.o
 obj-$(CONFIG_ATMEL_PIT)		+= timer-atmel-pit.o
 obj-$(CONFIG_ATMEL_ST)		+= timer-atmel-st.o
-obj-$(CONFIG_ATMEL_TCB_CLKSRC)	+= tcb_clksrc.o
+obj-$(CONFIG_ATMEL_TCB_CLKSRC) += tcb_clksrc.o
+obj-$(CONFIG_ATMEL_ARM_TCB_CLKSRC)	+= timer-atmel-tcb.o
 obj-$(CONFIG_X86_PM_TIMER)	+= acpi_pm.o
 obj-$(CONFIG_SCx200HR_TIMER)	+= scx200_hrt.o
 obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC)	+= cs5535-clockevt.o
diff --git a/drivers/clocksource/timer-atmel-tcb.c b/drivers/clocksource/timer-atmel-tcb.c
new file mode 100644
index 000000000000..bbbacf8c46b0
--- /dev/null
+++ b/drivers/clocksource/timer-atmel-tcb.c
@@ -0,0 +1,608 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/regmap.h>
+#include <linux/sched_clock.h>
+#include <soc/at91/atmel_tcb.h>
+
+static struct atmel_tcb_clksrc {
+	struct clocksource clksrc;
+	struct clock_event_device clkevt;
+	struct regmap *regmap;
+	void __iomem *base;
+	struct clk *clk[2];
+	char name[20];
+	int channels[2];
+	int bits;
+	int irq;
+	struct {
+		u32 cmr;
+		u32 imr;
+		u32 rc;
+		bool clken;
+	} cache[2];
+	u32 bmr_cache;
+	bool registered;
+} tc = {
+	.clksrc = {
+		.rating		= 200,
+		.mask		= CLOCKSOURCE_MASK(32),
+		.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+	},
+	.clkevt	= {
+		.features	= CLOCK_EVT_FEAT_ONESHOT,
+		/* Should be lower than at91rm9200's system timer */
+		.rating		= 125,
+	},
+};
+
+static struct tc_clkevt_device {
+	struct clock_event_device clkevt;
+	struct regmap *regmap;
+	void __iomem *base;
+	struct clk *slow_clk;
+	struct clk *clk;
+	char name[20];
+	int channel;
+	int irq;
+	struct {
+		u32 cmr;
+		u32 imr;
+		u32 rc;
+		bool clken;
+	} cache;
+	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,
+	},
+};
+
+/*
+ * Clockevent device using its own channel
+ */
+static int tc_clkevt2_shutdown(struct clock_event_device *d)
+{
+	writel(0xff, tce.base + ATMEL_TC_IDR(tce.channel));
+	writel(ATMEL_TC_CCR_CLKDIS, tce.base + ATMEL_TC_CCR(tce.channel));
+	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 */
+	writel(ATMEL_TC_CMR_TCLK(4) | ATMEL_TC_CMR_CPCSTOP |
+	       ATMEL_TC_CMR_WAVE | ATMEL_TC_CMR_WAVESEL_UPRC,
+	       tce.base + ATMEL_TC_CMR(tce.channel));
+	writel(ATMEL_TC_CPCS, tce.base + ATMEL_TC_IER(tce.channel));
+
+	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 */
+	writel(ATMEL_TC_CMR_TCLK(4) | ATMEL_TC_CMR_WAVE |
+	       ATMEL_TC_CMR_WAVESEL_UPRC,
+	       tce.base + ATMEL_TC_CMR(tce.channel));
+	writel((32768 + HZ / 2) / HZ, tce.base + ATMEL_TC_RC(tce.channel));
+
+	/* Enable clock and interrupts on RC compare */
+	writel(ATMEL_TC_CPCS, tce.base + ATMEL_TC_IER(tce.channel));
+	writel(ATMEL_TC_CCR_CLKEN | ATMEL_TC_CCR_SWTRG,
+	       tce.base + ATMEL_TC_CCR(tce.channel));
+
+	return 0;
+}
+
+static int tc_clkevt2_next_event(unsigned long delta,
+				 struct clock_event_device *d)
+{
+	writel(delta, tce.base + ATMEL_TC_RC(tce.channel));
+	writel(ATMEL_TC_CCR_CLKEN | ATMEL_TC_CCR_SWTRG,
+	       tce.base + ATMEL_TC_CCR(tce.channel));
+
+	return 0;
+}
+
+static irqreturn_t tc_clkevt2_irq(int irq, void *handle)
+{
+	unsigned int sr;
+
+	sr = readl(tce.base + ATMEL_TC_SR(tce.channel));
+	if (sr & ATMEL_TC_CPCS) {
+		tce.clkevt.event_handler(&tce.clkevt);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static void tc_clkevt2_suspend(struct clock_event_device *d)
+{
+	tce.cache.cmr = readl(tce.base + ATMEL_TC_CMR(tce.channel));
+	tce.cache.imr = readl(tce.base + ATMEL_TC_IMR(tce.channel));
+	tce.cache.rc = readl(tce.base + ATMEL_TC_RC(tce.channel));
+	tce.cache.clken = !!(readl(tce.base + ATMEL_TC_SR(tce.channel)) &
+				ATMEL_TC_CLKSTA);
+}
+
+static void tc_clkevt2_resume(struct clock_event_device *d)
+{
+	/* Restore registers for the channel, RA and RB are not used  */
+	writel(tce.cache.cmr, tc.base + ATMEL_TC_CMR(tce.channel));
+	writel(tce.cache.rc, tc.base + ATMEL_TC_RC(tce.channel));
+	writel(0, tc.base + ATMEL_TC_RA(tce.channel));
+	writel(0, tc.base + ATMEL_TC_RB(tce.channel));
+	/* Disable all the interrupts */
+	writel(0xff, tc.base + ATMEL_TC_IDR(tce.channel));
+	/* Reenable interrupts that were enabled before suspending */
+	writel(tce.cache.imr, tc.base + ATMEL_TC_IER(tce.channel));
+
+	/* Start the clock if it was used */
+	if (tce.cache.clken)
+		writel(ATMEL_TC_CCR_CLKEN | ATMEL_TC_CCR_SWTRG,
+		       tc.base + ATMEL_TC_CCR(tce.channel));
+}
+
+static int __init tc_clkevt_register(struct device_node *node,
+				     struct regmap *regmap, void __iomem *base,
+				     int channel, int irq, int bits)
+{
+	int ret;
+
+	tce.regmap = regmap;
+	tce.base = base;
+	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,
+	tce.clkevt.suspend = tc_clkevt2_suspend,
+	tce.clkevt.resume = tc_clkevt2_resume,
+
+	/* 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, BIT(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;
+}
+
+/*
+ * Clocksource and clockevent using the same channel(s)
+ */
+static u64 tc_get_cycles(struct clocksource *cs)
+{
+	u32 lower, upper;
+
+	do {
+		upper = readl_relaxed(tc.base + ATMEL_TC_CV(tc.channels[1]));
+		lower = readl_relaxed(tc.base + ATMEL_TC_CV(tc.channels[0]));
+	} while (upper != readl_relaxed(tc.base + ATMEL_TC_CV(tc.channels[1])));
+
+	return (upper << 16) | lower;
+}
+
+static u64 tc_get_cycles32(struct clocksource *cs)
+{
+	return readl_relaxed(tc.base + ATMEL_TC_CV(tc.channels[0]));
+}
+
+static u64 notrace tc_sched_clock_read(void)
+{
+	return tc_get_cycles(&tc.clksrc);
+}
+
+static u64 notrace tc_sched_clock_read32(void)
+{
+	return tc_get_cycles32(&tc.clksrc);
+}
+
+static int tcb_clkevt_next_event(unsigned long delta,
+				 struct clock_event_device *d)
+{
+	u32 old, next, cur;
+
+
+	old = readl(tc.base + ATMEL_TC_CV(tc.channels[0]));
+	next = old + delta;
+	writel(next, tc.base + ATMEL_TC_RC(tc.channels[0]));
+	cur = readl(tc.base + ATMEL_TC_CV(tc.channels[0]));
+
+	/* check whether the delta elapsed while setting the register */
+	if ((next < old && cur < old && cur > next) ||
+	    (next > old && (cur < old || cur > next))) {
+		/*
+		 * Clear the CPCS bit in the status register to avoid
+		 * generating a spurious interrupt next time a valid
+		 * timer event is configured.
+		 */
+		old = readl(tc.base + ATMEL_TC_SR(tc.channels[0]));
+		return -ETIME;
+	}
+
+	writel(ATMEL_TC_CPCS, tc.base + ATMEL_TC_IER(tc.channels[0]));
+
+	return 0;
+}
+
+static irqreturn_t tc_clkevt_irq(int irq, void *handle)
+{
+	unsigned int sr;
+
+	sr = readl(tc.base + ATMEL_TC_SR(tc.channels[0]));
+	if (sr & ATMEL_TC_CPCS) {
+		tc.clkevt.event_handler(&tc.clkevt);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static int tcb_clkevt_oneshot(struct clock_event_device *dev)
+{
+	if (clockevent_state_oneshot(dev))
+		return 0;
+
+	/*
+	 * Because both clockevent devices may share the same IRQ, we don't want
+	 * the less likely one to stay requested
+	 */
+	return request_irq(tc.irq, tc_clkevt_irq, IRQF_TIMER | IRQF_SHARED,
+			   tc.name, &tc);
+}
+
+static int tcb_clkevt_shutdown(struct clock_event_device *dev)
+{
+	writel(0xff, tc.base + ATMEL_TC_IDR(tc.channels[0]));
+	if (tc.bits == 16)
+		writel(0xff, tc.base + ATMEL_TC_IDR(tc.channels[1]));
+
+	if (!clockevent_state_detached(dev))
+		free_irq(tc.irq, &tc);
+
+	return 0;
+}
+
+static void __init tcb_setup_dual_chan(struct atmel_tcb_clksrc *tc,
+				       int mck_divisor_idx)
+{
+	/* first channel: waveform mode, input mclk/8, clock TIOA on overflow */
+	writel(mck_divisor_idx			/* likely divide-by-8 */
+	       | ATMEL_TC_CMR_WAVE
+	       | ATMEL_TC_CMR_WAVESEL_UP	/* free-run */
+	       | ATMEL_TC_CMR_ACPA(SET)		/* TIOA rises at 0 */
+	       | ATMEL_TC_CMR_ACPC(CLEAR),	/* (duty cycle 50%) */
+	       tc->base + ATMEL_TC_CMR(tc->channels[0]));
+	writel(0x0000, tc->base + ATMEL_TC_RA(tc->channels[0]));
+	writel(0x8000, tc->base + ATMEL_TC_RC(tc->channels[0]));
+	writel(0xff, tc->base + ATMEL_TC_IDR(tc->channels[0]));	/* no irqs */
+	writel(ATMEL_TC_CCR_CLKEN, tc->base + ATMEL_TC_CCR(tc->channels[0]));
+
+	/* second channel: waveform mode, input TIOA */
+	writel(ATMEL_TC_CMR_XC(tc->channels[1])		/* input: TIOA */
+	       | ATMEL_TC_CMR_WAVE
+	       | ATMEL_TC_CMR_WAVESEL_UP,		/* free-run */
+	       tc->base + ATMEL_TC_CMR(tc->channels[1]));
+	writel(0xff, tc->base + ATMEL_TC_IDR(tc->channels[1]));	/* no irqs */
+	writel(ATMEL_TC_CCR_CLKEN, tc->base + ATMEL_TC_CCR(tc->channels[1]));
+
+	/* chain both channel, we assume the previous channel */
+	regmap_write(tc->regmap, ATMEL_TC_BMR,
+		     ATMEL_TC_BMR_TCXC(1 + tc->channels[1], tc->channels[1]));
+	/* then reset all the timers */
+	regmap_write(tc->regmap, ATMEL_TC_BCR, ATMEL_TC_BCR_SYNC);
+}
+
+static void __init tcb_setup_single_chan(struct atmel_tcb_clksrc *tc,
+					 int mck_divisor_idx)
+{
+	/* channel 0:  waveform mode, input mclk/8 */
+	writel(mck_divisor_idx			/* likely divide-by-8 */
+	       | ATMEL_TC_CMR_WAVE
+	       | ATMEL_TC_CMR_WAVESEL_UP,	/* free-run */
+	       tc->base + ATMEL_TC_CMR(tc->channels[0]));
+	writel(0xff, tc->base + ATMEL_TC_IDR(tc->channels[0]));	/* no irqs */
+	writel(ATMEL_TC_CCR_CLKEN, tc->base + ATMEL_TC_CCR(tc->channels[0]));
+
+	/* then reset all the timers */
+	regmap_write(tc->regmap, ATMEL_TC_BCR, ATMEL_TC_BCR_SYNC);
+}
+
+static void tc_clksrc_suspend(struct clocksource *cs)
+{
+	int i;
+
+	for (i = 0; i < 1 + (tc.bits == 16); i++) {
+		tc.cache[i].cmr = readl(tc.base + ATMEL_TC_CMR(tc.channels[i]));
+		tc.cache[i].imr = readl(tc.base + ATMEL_TC_IMR(tc.channels[i]));
+		tc.cache[i].rc = readl(tc.base + ATMEL_TC_RC(tc.channels[i]));
+		tc.cache[i].clken = !!(readl(tc.base +
+					     ATMEL_TC_SR(tc.channels[i])) &
+				       ATMEL_TC_CLKSTA);
+	}
+
+	if (tc.bits == 16)
+		regmap_read(tc.regmap, ATMEL_TC_BMR, &tc.bmr_cache);
+}
+
+static void tc_clksrc_resume(struct clocksource *cs)
+{
+	int i;
+
+	for (i = 0; i < 1 + (tc.bits == 16); i++) {
+		/* Restore registers for the channel, RA and RB are not used  */
+		writel(tc.cache[i].cmr, tc.base + ATMEL_TC_CMR(tc.channels[i]));
+		writel(tc.cache[i].rc, tc.base + ATMEL_TC_RC(tc.channels[i]));
+		writel(0, tc.base + ATMEL_TC_RA(tc.channels[i]));
+		writel(0, tc.base + ATMEL_TC_RB(tc.channels[i]));
+		/* Disable all the interrupts */
+		writel(0xff, tc.base + ATMEL_TC_IDR(tc.channels[i]));
+		/* Reenable interrupts that were enabled before suspending */
+		writel(tc.cache[i].imr, tc.base + ATMEL_TC_IER(tc.channels[i]));
+
+		/* Start the clock if it was used */
+		if (tc.cache[i].clken)
+			writel(ATMEL_TC_CCR_CLKEN, tc.base +
+			       ATMEL_TC_CCR(tc.channels[i]));
+	}
+
+	/* in case of dual channel, chain channels */
+	if (tc.bits == 16)
+		regmap_write(tc.regmap, ATMEL_TC_BMR, tc.bmr_cache);
+	/* Finally, trigger all the channels*/
+	regmap_write(tc.regmap, ATMEL_TC_BCR, ATMEL_TC_BCR_SYNC);
+}
+
+static int __init tcb_clksrc_register(struct device_node *node,
+				      struct regmap *regmap, void __iomem *base,
+				      int channel, int channel1, int irq,
+				      int bits)
+{
+	u32 rate, divided_rate = 0;
+	int best_divisor_idx = -1;
+	int i, err = -1;
+	u64 (*tc_sched_clock)(void);
+
+	tc.regmap = regmap;
+	tc.base = base;
+	tc.channels[0] = channel;
+	tc.channels[1] = channel1;
+	tc.irq = irq;
+	tc.bits = bits;
+
+	tc.clk[0] = tcb_clk_get(node, tc.channels[0]);
+	if (IS_ERR(tc.clk[0]))
+		return PTR_ERR(tc.clk[0]);
+	err = clk_prepare_enable(tc.clk[0]);
+	if (err) {
+		pr_debug("can't enable T0 clk\n");
+		goto err_clk;
+	}
+
+	/* How fast will we be counting?  Pick something over 5 MHz.  */
+	rate = (u32)clk_get_rate(tc.clk[0]);
+	for (i = 0; i < 5; i++) {
+		unsigned int divisor = atmel_tc_divisors[i];
+		unsigned int tmp;
+
+		if (!divisor)
+			continue;
+
+		tmp = rate / divisor;
+		pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp);
+		if (best_divisor_idx > 0) {
+			if (tmp < 5 * 1000 * 1000)
+				continue;
+		}
+		divided_rate = tmp;
+		best_divisor_idx = i;
+	}
+
+	if (tc.bits == 32) {
+		tc.clksrc.read = tc_get_cycles32;
+		tcb_setup_single_chan(&tc, best_divisor_idx);
+		tc_sched_clock = tc_sched_clock_read32;
+		snprintf(tc.name, sizeof(tc.name), "%s:%d",
+			 kbasename(node->parent->full_name), tc.channels[0]);
+	} else {
+		tc.clk[1] = tcb_clk_get(node, tc.channels[1]);
+		if (IS_ERR(tc.clk[1]))
+			goto err_disable_t0;
+
+		err = clk_prepare_enable(tc.clk[1]);
+		if (err) {
+			pr_debug("can't enable T1 clk\n");
+			goto err_clk1;
+		}
+		tc.clksrc.read = tc_get_cycles,
+		tcb_setup_dual_chan(&tc, best_divisor_idx);
+		tc_sched_clock = tc_sched_clock_read;
+		snprintf(tc.name, sizeof(tc.name), "%s:%d,%d",
+			 kbasename(node->parent->full_name), tc.channels[0],
+			 tc.channels[1]);
+	}
+
+	pr_debug("%s at %d.%03d MHz\n", tc.name,
+		 divided_rate / 1000000,
+		 ((divided_rate + 500000) % 1000000) / 1000);
+
+	tc.clksrc.name = tc.name;
+	tc.clksrc.suspend = tc_clksrc_suspend;
+	tc.clksrc.resume = tc_clksrc_resume;
+
+	err = clocksource_register_hz(&tc.clksrc, divided_rate);
+	if (err)
+		goto err_disable_t1;
+
+	sched_clock_register(tc_sched_clock, 32, divided_rate);
+
+	tc.registered = true;
+
+	/* Set up and register clockevents */
+	tc.clkevt.name = tc.name;
+	tc.clkevt.cpumask = cpumask_of(0);
+	tc.clkevt.set_next_event = tcb_clkevt_next_event;
+	tc.clkevt.set_state_oneshot = tcb_clkevt_oneshot;
+	tc.clkevt.set_state_shutdown = tcb_clkevt_shutdown;
+	clockevents_config_and_register(&tc.clkevt, divided_rate, 1,
+					BIT(tc.bits) - 1);
+
+	return 0;
+
+err_disable_t1:
+	if (tc.bits == 16)
+		clk_disable_unprepare(tc.clk[1]);
+
+err_clk1:
+	if (tc.bits == 16)
+		clk_put(tc.clk[1]);
+
+err_disable_t0:
+	clk_disable_unprepare(tc.clk[0]);
+
+err_clk:
+	clk_put(tc.clk[0]);
+
+	pr_err("%s: unable to register clocksource/clockevent\n",
+	       tc.clksrc.name);
+
+	return err;
+}
+
+static int __init tcb_clksrc_init(struct device_node *node)
+{
+	const struct of_device_id *match;
+	const struct atmel_tcb_info *tcb_info;
+	struct regmap *regmap;
+	void __iomem *tcb_base;
+	u32 channel;
+	int bits, irq, err, chan1 = -1;
+
+	if (tc.registered && tce.registered)
+		return -ENODEV;
+
+	/*
+	 * The regmap has to be used to access registers that are shared
+	 * between channels on the same TCB but we keep direct IO access for
+	 * the counters to avoid the impact on performance
+	 */
+	regmap = syscon_node_to_regmap(node->parent);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	tcb_base = of_iomap(node->parent, 0);
+	if (!tcb_base) {
+		pr_err("%s +%d %s\n", __FILE__, __LINE__, __func__);
+		return -ENXIO;
+	}
+
+	match = of_match_node(atmel_tcb_dt_ids, node->parent);
+	tcb_info = match->data;
+	bits = tcb_info->bits;
+
+	err = of_property_read_u32_index(node, "reg", 0, &channel);
+	if (err)
+		return err;
+
+	irq = tcb_irq_get(node, channel);
+	if (irq < 0)
+		return irq;
+
+	if (tc.registered)
+		return tc_clkevt_register(node, regmap, tcb_base, channel, irq,
+					  bits);
+
+	if (bits == 16) {
+		of_property_read_u32_index(node, "reg", 1, &chan1);
+		if (chan1 == -1) {
+			if (tce.registered) {
+				pr_err("%s: clocksource needs two channels\n",
+				       node->parent->full_name);
+				return -EINVAL;
+			} else {
+				return tc_clkevt_register(node, regmap,
+							  tcb_base, channel,
+							  irq, bits);
+			}
+		}
+	}
+
+	return tcb_clksrc_register(node, regmap, tcb_base, channel, chan1, irq,
+				   bits);
+}
+CLOCKSOURCE_OF_DECLARE(atmel_tcb_clksrc, "atmel,tcb-timer",
+		       tcb_clksrc_init);
-- 
2.17.0

[PATCH v4 3/6] clocksource/drivers: atmel-pit: make option silent

[Alexandre Belloni]

To conform with the other option, make the ATMEL_PIT option silent so it
can be selected from the platform

Tested-by: Alexander Dahl <ada@thorsis.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/clocksource/Kconfig | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 540892273a8d..cb635d5d7f42 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -384,8 +384,11 @@ config ARMV7M_SYSTICK
 	  This options enables support for the ARMv7M system timer unit
 
 config ATMEL_PIT
+	bool "Microchip ARM Periodic Interval Timer (PIT)" if COMPILE_TEST
 	select TIMER_OF if OF
-	def_bool SOC_AT91SAM9 || SOC_SAMA5
+	help
+	  This enables build of clocksource and clockevent driver for
+	  the integrated PIT in Microchip ARM SoCs.
 
 config ATMEL_ST
 	bool "Atmel ST timer support" if COMPILE_TEST
-- 
2.17.0

[PATCH v4 4/6] ARM: at91: Implement clocksource selection

[Alexandre Belloni]

Allow selecting and unselecting the PIT clocksource driver so it doesn't
have to be compile when unused.

Tested-by: Alexander Dahl <ada@thorsis.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 arch/arm/mach-at91/Kconfig | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 1254bf9d91b4..64f18cd220b9 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -106,6 +106,31 @@ config SOC_AT91SAM9
 	    AT91SAM9X35
 	    AT91SAM9XE
 
+comment "Clocksource driver selection"
+
+config ATMEL_CLOCKSOURCE_PIT
+	bool "Periodic Interval Timer (PIT) support"
+	depends on SOC_AT91SAM9 || SOC_SAMA5
+	default SOC_AT91SAM9 || SOC_SAMA5
+	select ATMEL_PIT
+	help
+	  Select this to get a clocksource based on the Atmel Periodic Interval
+	  Timer. It has a relatively low resolution and the TC Block clocksource
+	  should be preferred.
+
+config ATMEL_CLOCKSOURCE_TCB
+	bool "Timer Counter Blocks (TCB) support"
+	depends on SOC_AT91RM9200 || SOC_AT91SAM9 || SOC_SAMA5 || COMPILE_TEST
+	default SOC_AT91RM9200 || SOC_AT91SAM9 || SOC_SAMA5
+	depends on !ATMEL_TCLIB
+	select ATMEL_ARM_TCB_CLKSRC
+	help
+	  Select this to get a high precision clocksource based on a
+	  TC block with a 5+ MHz base clock rate.
+	  On platforms with 16-bit counters, two timer channels are combined
+	  to make a single 32-bit timer.
+	  It can also be used as a clock event device supporting oneshot mode.
+
 config HAVE_AT91_UTMI
 	bool
 
-- 
2.17.0

[PATCH v4 5/6] ARM: configs: at91: use new TCB timer driver

[Alexandre Belloni]

Unselecting ATMEL_TCLIB switches the TCB timer driver from tcb_clksrc to
timer-atmel-tcb.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 arch/arm/configs/at91_dt_defconfig | 1 -
 arch/arm/configs/sama5_defconfig   | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/arm/configs/at91_dt_defconfig b/arch/arm/configs/at91_dt_defconfig
index e4b1be66b3f5..09f262e59fef 100644
--- a/arch/arm/configs/at91_dt_defconfig
+++ b/arch/arm/configs/at91_dt_defconfig
@@ -64,7 +64,6 @@ CONFIG_BLK_DEV_LOOP=y
 CONFIG_BLK_DEV_RAM=y
 CONFIG_BLK_DEV_RAM_COUNT=4
 CONFIG_BLK_DEV_RAM_SIZE=8192
-CONFIG_ATMEL_TCLIB=y
 CONFIG_ATMEL_SSC=y
 CONFIG_SCSI=y
 CONFIG_BLK_DEV_SD=y
diff --git a/arch/arm/configs/sama5_defconfig b/arch/arm/configs/sama5_defconfig
index 2080025556b5..f2bbc6339ca6 100644
--- a/arch/arm/configs/sama5_defconfig
+++ b/arch/arm/configs/sama5_defconfig
@@ -75,7 +75,6 @@ CONFIG_BLK_DEV_LOOP=y
 CONFIG_BLK_DEV_RAM=y
 CONFIG_BLK_DEV_RAM_COUNT=4
 CONFIG_BLK_DEV_RAM_SIZE=8192
-CONFIG_ATMEL_TCLIB=y
 CONFIG_ATMEL_SSC=y
 CONFIG_EEPROM_AT24=y
 CONFIG_SCSI=y
-- 
2.17.0

[PATCH v4 6/6] ARM: configs: at91: unselect PIT

[Alexandre Belloni]

The PIT is not required anymore to successfully boot and may actually harm
in case preempt-rt is used because the PIT interrupt is shared.
Disable it so the TCB clocksource is used.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 arch/arm/configs/at91_dt_defconfig | 1 +
 arch/arm/configs/sama5_defconfig   | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm/configs/at91_dt_defconfig b/arch/arm/configs/at91_dt_defconfig
index 09f262e59fef..f4b253bd05ed 100644
--- a/arch/arm/configs/at91_dt_defconfig
+++ b/arch/arm/configs/at91_dt_defconfig
@@ -19,6 +19,7 @@ CONFIG_ARCH_MULTI_V5=y
 CONFIG_ARCH_AT91=y
 CONFIG_SOC_AT91RM9200=y
 CONFIG_SOC_AT91SAM9=y
+# CONFIG_ATMEL_CLOCKSOURCE_PIT is not set
 CONFIG_AEABI=y
 CONFIG_UACCESS_WITH_MEMCPY=y
 CONFIG_ZBOOT_ROM_TEXT=0x0
diff --git a/arch/arm/configs/sama5_defconfig b/arch/arm/configs/sama5_defconfig
index f2bbc6339ca6..be92871ab155 100644
--- a/arch/arm/configs/sama5_defconfig
+++ b/arch/arm/configs/sama5_defconfig
@@ -20,6 +20,7 @@ CONFIG_ARCH_AT91=y
 CONFIG_SOC_SAMA5D2=y
 CONFIG_SOC_SAMA5D3=y
 CONFIG_SOC_SAMA5D4=y
+# CONFIG_ATMEL_CLOCKSOURCE_PIT is not set
 CONFIG_AEABI=y
 CONFIG_UACCESS_WITH_MEMCPY=y
 CONFIG_ZBOOT_ROM_TEXT=0x0
-- 
2.17.0

Re: [PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[Sebastian Andrzej Siewior]

On 2018-04-18 12:51:37 [+0200], Alexandre Belloni wrote:
> Hi,

Hi,

please keep on Cc if you intend to repost this.

> This series gets back on the TCB drivers rework. It introduces a new driver to
> handle the clocksource and clockevent devices.

So you don't want the old thing we have in -RT. I remember you (the
atmel folks) wanted something different the last time I posted the
patches.

> As a reminder, this is necessary because:
>  - the current tcb_clksrc driver is probed too late to be able to be used at
>    boot and we now have SoCs that don't have a PIT. They currently are not able
>    to boot a mainline kernel.
>  - using the PIT doesn't work well with preempt-rt because its interrupt is
>    shared (in particular with the UART and their interrupt flags are
>    incompatible)

If you could get rid of this:
| clocksource: Switched to clocksource timer@f0010000:0
| BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974
| in_atomic(): 1, irqs_disabled(): 128, pid: 1, name: swapper
| Preemption disabled at:
| [<c014f7ac>] __handle_domain_irq+0x40/0xdc
| Hardware name: Atmel SAMA5
| [<c010e14c>] (unwind_backtrace) from [<c010bd74>] (show_stack+0x10/0x14)
| [<c010bd74>] (show_stack) from [<c013b314>] (___might_sleep+0x16c/0x1c0)
| [<c013b314>] (___might_sleep) from [<c06696f0>] (rt_spin_lock+0x40/0x80)
| [<c06696f0>] (rt_spin_lock) from [<c046e030>] (clk_enable_lock+0x30/0xe4)
| [<c046e030>] (clk_enable_lock) from [<c046ea4c>] (clk_core_disable_lock+0xc/0x1c)
| [<c046ea4c>] (clk_core_disable_lock) from [<c059d07c>] (tc_clkevt2_shutdown+0x64/0x6c)
| [<c059d07c>] (tc_clkevt2_shutdown) from [<c059d09c>] (tc_clkevt2_set_oneshot+0x18/0x78)
| [<c059d09c>] (tc_clkevt2_set_oneshot) from [<c0172a00>] (clockevents_switch_state+0xb8/0x130)
| [<c0172a00>] (clockevents_switch_state) from [<c0173a60>] (tick_switch_to_oneshot+0x48/0xb8)
| [<c0173a60>] (tick_switch_to_oneshot) from [<c0165a0c>] (hrtimer_run_queues+0xf0/0x15c)
| [<c0165a0c>] (hrtimer_run_queues) from [<c0164010>] (run_local_timers+0x8/0x38)
| [<c0164010>] (run_local_timers) from [<c0164070>] (update_process_times+0x30/0x60)
| [<c0164070>] (update_process_times) from [<c0173008>] (tick_handle_periodic+0x1c/0x90)
| [<c0173008>] (tick_handle_periodic) from [<c059c954>] (tc_clkevt2_irq+0x38/0x48)
| [<c059c954>] (tc_clkevt2_irq) from [<c014fe6c>] (__handle_irq_event_percpu+0x7c/0x28c)

that would be so awesome.

>  - the current solution is wasting some TCB channels
> 
> The plan is to get this driver upstream, then convert the TCB PWM driver to be
> able to get rid of the tcb_clksrc driver along with atmel_tclib.

The config options are now less than optimal (for me at least). On
oldconfig it asks you for PIT and I say selected no because I wanted the
new one. So I end up with nothing.
Not sure you want do something about it…

Is the resolution more or the same compared what we have in -RT? On an
idle system this clocks goes up to 180us/ 190us while the old clock
started at 160us and moved to around 180us after one hackbench
invocation. This could be nothing, it could be a lower frequency of the
clockevents device.

If you intend to stick with this driver then I would replace the current
hack in -RT with this series.

Sebastian

Re: [PATCH v4 1/6] ARM: at91: add TCB registers definitions

[Sebastian Andrzej Siewior]

On 2018-04-18 12:51:38 [+0200], Alexandre Belloni wrote:
> diff --git a/include/soc/at91/atmel_tcb.h b/include/soc/at91/atmel_tcb.h
> new file mode 100644
> index 000000000000..d263ea677225
> --- /dev/null
> +++ b/include/soc/at91/atmel_tcb.h
…
> +static inline struct clk *tcb_clk_get(struct device_node *node, int channel)
> +{
> +	struct clk *clk;
> +	char clk_name[] = "t0_clk";
> +
> +	clk_name[1] += channel;
> +	clk = of_clk_get_by_name(node->parent, clk_name);
> +	if (!IS_ERR(clk))
> +		return clk;
> +
> +	return of_clk_get_by_name(node->parent, "t0_clk");
> +}
> +
> +static inline int tcb_irq_get(struct device_node *node, int channel)
> +{
> +	int irq;
> +
> +	irq = of_irq_get(node->parent, channel);
> +	if (irq > 0)
> +		return irq;
> +
> +	return of_irq_get(node->parent, 0);
> +}
> +
> +static const u8 atmel_tc_divisors[5] = { 2, 8, 32, 128, 0, };
> +
> +struct atmel_tcb_info {
> +	int bits;
> +};
> +
> +static const struct atmel_tcb_info atmel_tcb_infos[] = {
> +	{ .bits = 16 },
> +	{ .bits = 32 },
> +};
> +
> +static const struct of_device_id atmel_tcb_dt_ids[] = {
> +	{
> +		.compatible = "atmel,at91rm9200-tcb",
> +		.data = &atmel_tcb_infos[0],
> +	}, {
> +		.compatible = "atmel,at91sam9x5-tcb",
> +		.data = &atmel_tcb_infos[1],
> +	}, {
> +		/* sentinel */
> +	}
> +};

After the series is applied, I see only one user of that file. The data
structures don't look like they belong here. Same goes for the static
inline of the code above.

> +#endif /* __SOC_ATMEL_TCB_H */

Sebastian

Re: [PATCH v4 1/6] ARM: at91: add TCB registers definitions

[Alexandre Belloni]

On 26/04/2018 18:52:43+0200, Sebastian Andrzej Siewior wrote:
> On 2018-04-18 12:51:38 [+0200], Alexandre Belloni wrote:
> > diff --git a/include/soc/at91/atmel_tcb.h b/include/soc/at91/atmel_tcb.h
> > new file mode 100644
> > index 000000000000..d263ea677225
> > --- /dev/null
> > +++ b/include/soc/at91/atmel_tcb.h
> …
> > +static inline struct clk *tcb_clk_get(struct device_node *node, int channel)
> > +{
> > +	struct clk *clk;
> > +	char clk_name[] = "t0_clk";
> > +
> > +	clk_name[1] += channel;
> > +	clk = of_clk_get_by_name(node->parent, clk_name);
> > +	if (!IS_ERR(clk))
> > +		return clk;
> > +
> > +	return of_clk_get_by_name(node->parent, "t0_clk");
> > +}
> > +
> > +static inline int tcb_irq_get(struct device_node *node, int channel)
> > +{
> > +	int irq;
> > +
> > +	irq = of_irq_get(node->parent, channel);
> > +	if (irq > 0)
> > +		return irq;
> > +
> > +	return of_irq_get(node->parent, 0);
> > +}
> > +
> > +static const u8 atmel_tc_divisors[5] = { 2, 8, 32, 128, 0, };
> > +
> > +struct atmel_tcb_info {
> > +	int bits;
> > +};
> > +
> > +static const struct atmel_tcb_info atmel_tcb_infos[] = {
> > +	{ .bits = 16 },
> > +	{ .bits = 32 },
> > +};
> > +
> > +static const struct of_device_id atmel_tcb_dt_ids[] = {
> > +	{
> > +		.compatible = "atmel,at91rm9200-tcb",
> > +		.data = &atmel_tcb_infos[0],
> > +	}, {
> > +		.compatible = "atmel,at91sam9x5-tcb",
> > +		.data = &atmel_tcb_infos[1],
> > +	}, {
> > +		/* sentinel */
> > +	}
> > +};
> 
> After the series is applied, I see only one user of that file. The data
> structures don't look like they belong here. Same goes for the static
> inline of the code above.
> 

There is another user coming later (the pwm driver) but I didn't repost,
I'll do so after this series is applied.

> > +#endif /* __SOC_ATMEL_TCB_H */
> 
> Sebastian

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[Alexandre Belloni]

On 26/04/2018 18:46:23+0200, Sebastian Andrzej Siewior wrote:
> On 2018-04-18 12:51:37 [+0200], Alexandre Belloni wrote:
> > Hi,
> 
> Hi,
> 
> please keep on Cc if you intend to repost this.
> 

Sure, I'll do.

> > This series gets back on the TCB drivers rework. It introduces a new driver to
> > handle the clocksource and clockevent devices.
> 
> So you don't want the old thing we have in -RT. I remember you (the
> atmel folks) wanted something different the last time I posted the
> patches.
> 

I don't remember you posted anything for the TCB. Wasn't it focused on
getting rid of the PIT irq?

As said below, this is solving multiple issues, including the one for
SoCs that don't have the PIT.

> > As a reminder, this is necessary because:
> >  - the current tcb_clksrc driver is probed too late to be able to be used at
> >    boot and we now have SoCs that don't have a PIT. They currently are not able
> >    to boot a mainline kernel.
> >  - using the PIT doesn't work well with preempt-rt because its interrupt is
> >    shared (in particular with the UART and their interrupt flags are
> >    incompatible)
> 
> If you could get rid of this:
> | clocksource: Switched to clocksource timer@f0010000:0
> | BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974
> | in_atomic(): 1, irqs_disabled(): 128, pid: 1, name: swapper
> | Preemption disabled at:
> | [<c014f7ac>] __handle_domain_irq+0x40/0xdc
> | Hardware name: Atmel SAMA5
> | [<c010e14c>] (unwind_backtrace) from [<c010bd74>] (show_stack+0x10/0x14)
> | [<c010bd74>] (show_stack) from [<c013b314>] (___might_sleep+0x16c/0x1c0)
> | [<c013b314>] (___might_sleep) from [<c06696f0>] (rt_spin_lock+0x40/0x80)
> | [<c06696f0>] (rt_spin_lock) from [<c046e030>] (clk_enable_lock+0x30/0xe4)
> | [<c046e030>] (clk_enable_lock) from [<c046ea4c>] (clk_core_disable_lock+0xc/0x1c)
> | [<c046ea4c>] (clk_core_disable_lock) from [<c059d07c>] (tc_clkevt2_shutdown+0x64/0x6c)
> | [<c059d07c>] (tc_clkevt2_shutdown) from [<c059d09c>] (tc_clkevt2_set_oneshot+0x18/0x78)
> | [<c059d09c>] (tc_clkevt2_set_oneshot) from [<c0172a00>] (clockevents_switch_state+0xb8/0x130)
> | [<c0172a00>] (clockevents_switch_state) from [<c0173a60>] (tick_switch_to_oneshot+0x48/0xb8)
> | [<c0173a60>] (tick_switch_to_oneshot) from [<c0165a0c>] (hrtimer_run_queues+0xf0/0x15c)
> | [<c0165a0c>] (hrtimer_run_queues) from [<c0164010>] (run_local_timers+0x8/0x38)
> | [<c0164010>] (run_local_timers) from [<c0164070>] (update_process_times+0x30/0x60)
> | [<c0164070>] (update_process_times) from [<c0173008>] (tick_handle_periodic+0x1c/0x90)
> | [<c0173008>] (tick_handle_periodic) from [<c059c954>] (tc_clkevt2_irq+0x38/0x48)
> | [<c059c954>] (tc_clkevt2_irq) from [<c014fe6c>] (__handle_irq_event_percpu+0x7c/0x28c)
> 
> that would be so awesome.
> 

Ok, if I understand correctly tc_clkevt2_set_oneshot is called from
atomic context so it shouldn't call tc_clkevt2_shutdown.

Back in 2016, tglx said:
"There was an earlier discussion about the clk stuff. Actually the lock
protecting disable/enable should be made raw, but there was some crap going on
in some of the clk callbacks which made that impossible. We realy should
revisit this."

Anyway, I'll try to avoid disabling the clock just to reenable it
afterwards.

(Actually, I've just checked before sending and I've found your patch,
I'll do something similar)

> >  - the current solution is wasting some TCB channels
> > 
> > The plan is to get this driver upstream, then convert the TCB PWM driver to be
> > able to get rid of the tcb_clksrc driver along with atmel_tclib.
> 
> The config options are now less than optimal (for me at least). On
> oldconfig it asks you for PIT and I say selected no because I wanted the
> new one. So I end up with nothing.
> Not sure you want do something about it…
> 

I don't think you ending up with nothing but probably you removed the
PIT and kept ATMEL_TCLIB which is the combination that is really
difficult to protect from. I don't think it is worth the added Kconfig
complexity.

> Is the resolution more or the same compared what we have in -RT? On an
> idle system this clocks goes up to 180us/ 190us while the old clock
> started at 160us and moved to around 180us after one hackbench
> invocation. This could be nothing, it could be a lower frequency of the
> clockevents device.
> 

The driver shouldn't change anything on that side.

> If you intend to stick with this driver then I would replace the current
> hack in -RT with this series.
> 

That is one of the goal, yes.

The remaining one would be "clocksource: TCLIB: Allow higher clock rates
for clock events"

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[Sebastian Andrzej Siewior]

On 2018-04-26 20:52:33 [+0200], Alexandre Belloni wrote:
> 
> I don't remember you posted anything for the TCB. Wasn't it focused on
> getting rid of the PIT irq?

the PIT irq which was shared with the UART one some devices, yes this
was part of it. The other essential piece was using a higher frequency
for the device:
  https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches/clocksource-tclib-allow-higher-clockrates.patch?h=linux-4.14.y-rt-patches

> As said below, this is solving multiple issues, including the one for
> SoCs that don't have the PIT.
will the PIT be removed? Where it needs the PIT?

> Ok, if I understand correctly tc_clkevt2_set_oneshot is called from
> atomic context so it shouldn't call tc_clkevt2_shutdown.
> 
> Back in 2016, tglx said:
> "There was an earlier discussion about the clk stuff. Actually the lock
> protecting disable/enable should be made raw, but there was some crap going on
> in some of the clk callbacks which made that impossible. We realy should
> revisit this."
> 
> Anyway, I'll try to avoid disabling the clock just to reenable it
> afterwards.
> 
> (Actually, I've just checked before sending and I've found your patch,
> I'll do something similar)
thanks.

> > >  - the current solution is wasting some TCB channels
> > > 
> > > The plan is to get this driver upstream, then convert the TCB PWM driver to be
> > > able to get rid of the tcb_clksrc driver along with atmel_tclib.
> > 
> > The config options are now less than optimal (for me at least). On
> > oldconfig it asks you for PIT and I say selected no because I wanted the
> > new one. So I end up with nothing.
> > Not sure you want do something about it…
> > 
> 
> I don't think you ending up with nothing but probably you removed the
> PIT and kept ATMEL_TCLIB which is the combination that is really
> difficult to protect from. I don't think it is worth the added Kconfig
> complexity.

TCLIB was still enabled yes. It is 'oldconfig'.

> > Is the resolution more or the same compared what we have in -RT? On an
> > idle system this clocks goes up to 180us/ 190us while the old clock
> > started at 160us and moved to around 180us after one hackbench
> > invocation. This could be nothing, it could be a lower frequency of the
> > clockevents device.
> > 
> 
> The driver shouldn't change anything on that side.
> 
> > If you intend to stick with this driver then I would replace the current
> > hack in -RT with this series.
> > 
> 
> That is one of the goal, yes.
> 
> The remaining one would be "clocksource: TCLIB: Allow higher clock rates
> for clock events"

I see. So I would need to keep that patch in queue after it was
dismissed from duty…

Sebastian

Re: [PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[Alexandre Belloni]

On 02/05/2018 15:34:18+0200, Sebastian Andrzej Siewior wrote:
> On 2018-04-26 20:52:33 [+0200], Alexandre Belloni wrote:
> > 
> > I don't remember you posted anything for the TCB. Wasn't it focused on
> > getting rid of the PIT irq?
> 
> the PIT irq which was shared with the UART one some devices, yes this
> was part of it. The other essential piece was using a higher frequency
> for the device:
>   https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches/clocksource-tclib-allow-higher-clockrates.patch?h=linux-4.14.y-rt-patches
> 
> > As said below, this is solving multiple issues, including the one for
> > SoCs that don't have the PIT.
> will the PIT be removed? Where it needs the PIT?
> 

The last patch is unselecting the PIT driver so by default it is not
enabled. The PIT driver will stay just in case someone has to use it
e.g. when they are using all the TCB channels for something else.
However, recent Atmel SoC have a TCB without any output so it can ony be
used as a timer. Some other SoCs don't have a PIT at all.

> > I don't think you ending up with nothing but probably you removed the
> > PIT and kept ATMEL_TCLIB which is the combination that is really
> > difficult to protect from. I don't think it is worth the added Kconfig
> > complexity.
> 
> TCLIB was still enabled yes. It is 'oldconfig'.
> 

Hum, ok, I'll try to provide a cleaner path.

> > The remaining one would be "clocksource: TCLIB: Allow higher clock rates
> > for clock events"
> 
> I see. So I would need to keep that patch in queue after it was
> dismissed from duty…

Boris suggested a DT binding to allow changing the rate but it didn't
reach consensus at the time. this is something that will ne to be
revived at some point and I would very much like having that upstream
too.

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v4 0/6] clocksource: rework Atmel TCB timer driver

[Sebastian Andrzej Siewior]

On 2018-05-02 20:10:46 [+0200], Alexandre Belloni wrote:
> > > As said below, this is solving multiple issues, including the one for
> > > SoCs that don't have the PIT.
> > will the PIT be removed? Where it needs the PIT?
> > 
> 
> The last patch is unselecting the PIT driver so by default it is not
> enabled. The PIT driver will stay just in case someone has to use it
> e.g. when they are using all the TCB channels for something else.
> However, recent Atmel SoC have a TCB without any output so it can ony be
> used as a timer. Some other SoCs don't have a PIT at all.

The question was more "does it make sense to keep the 'old' PIT driver
around or can it be removed and the TCB driver will be used by
everyone"?

> > > The remaining one would be "clocksource: TCLIB: Allow higher clock rates
> > > for clock events"
> > 
> > I see. So I would need to keep that patch in queue after it was
> > dismissed from duty…
> 
> Boris suggested a DT binding to allow changing the rate but it didn't
> reach consensus at the time. this is something that will ne to be
> revived at some point and I would very much like having that upstream
> too.

Does make sense to have a low frequency clock here? I think from
clocksource point of view it makes sense to have it (highres) enabled
and not having to adjust the DT first (not to mention to learn about
it).

Sebastian