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Subject[PATCH v9 2/2] clocksource: Add Intel Keem Bay timer support
Date
From: Shruthi Sanil <shruthi.sanil@intel.com>

The Intel Keem Bay timer driver supports clocksource and clockevent
features for the timer IP used in Intel Keem Bay SoC.
The timer block supports 1 free running counter and 8 timers.
The free running counter can be used as a clocksource and
the timers can be used as clockevent. Each timer is capable of
generating individual interrupt.
Both the features are enabled through the timer general config register.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shruthi Sanil <shruthi.sanil@intel.com>
---
MAINTAINERS | 6 +
drivers/clocksource/Kconfig | 11 ++
drivers/clocksource/Makefile | 1 +
drivers/clocksource/timer-keembay.c | 227 ++++++++++++++++++++++++++++
4 files changed, 245 insertions(+)
create mode 100644 drivers/clocksource/timer-keembay.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 05fd080b82f3..90af9439d529 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9791,6 +9791,12 @@ F: drivers/crypto/keembay/keembay-ocs-hcu-core.c
F: drivers/crypto/keembay/ocs-hcu.c
F: drivers/crypto/keembay/ocs-hcu.h

+INTEL KEEM BAY TIMER DRIVER
+M: Shruthi Sanil <shruthi.sanil@intel.com>
+S: Maintained
+F: Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml
+F: drivers/clocksource/timer-keembay.c
+
INTEL THUNDER BAY EMMC PHY DRIVER
M: Nandhini Srikandan <nandhini.srikandan@intel.com>
M: Rashmi A <rashmi.a@intel.com>
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index cfb8ea0df3b1..65b6cf916e5a 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -721,4 +721,15 @@ config MICROCHIP_PIT64B
modes and high resolution. It is used as a clocksource
and a clockevent.

+config KEEMBAY_TIMER
+ bool "Intel Keem Bay timer"
+ depends on ARCH_KEEMBAY || COMPILE_TEST
+ select TIMER_OF
+ help
+ This option enables the support for the Intel Keem Bay
+ general purpose timer and free running counter driver.
+ Each timer can generate an individual interrupt and
+ supports oneshot and periodic modes.
+ The 64-bit counter can be used as a clock source.
+
endmenu
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index fa5f624eadb6..dff6458ef9e5 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -89,3 +89,4 @@ obj-$(CONFIG_GX6605S_TIMER) += timer-gx6605s.o
obj-$(CONFIG_HYPERV_TIMER) += hyperv_timer.o
obj-$(CONFIG_MICROCHIP_PIT64B) += timer-microchip-pit64b.o
obj-$(CONFIG_MSC313E_TIMER) += timer-msc313e.o
+obj-$(CONFIG_KEEMBAY_TIMER) += timer-keembay.o
diff --git a/drivers/clocksource/timer-keembay.c b/drivers/clocksource/timer-keembay.c
new file mode 100644
index 000000000000..385863c064cd
--- /dev/null
+++ b/drivers/clocksource/timer-keembay.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel Keem Bay Timer driver
+ *
+ * Copyright (C) 2020 Intel Corporation
+ */
+
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/regmap.h>
+
+#include "timer-of.h"
+
+/* Timer register offset */
+#define TIM_CNT_VAL_OFFSET 0x0
+#define TIM_RELOAD_VAL_OFFSET 0x4
+#define TIM_CONFIG_OFFSET 0x8
+
+/* Bit fields of timer general config register */
+#define TIM_CONFIG_PRESCALER_ENABLE BIT(2)
+#define TIM_CONFIG_COUNTER_ENABLE BIT(0)
+
+/* Bit fields of timer config register */
+#define TIM_CONFIG_INTERRUPT_PENDING BIT(4)
+#define TIM_CONFIG_INTERRUPT_ENABLE BIT(2)
+#define TIM_CONFIG_RESTART BIT(1)
+#define TIM_CONFIG_ENABLE BIT(0)
+
+#define TIM_GEN_MASK GENMASK(31, 12)
+#define TIM_RATING 200
+#define TIM_CLKSRC_MASK_BITS 64
+
+#define TIMER_NAME_SIZE 25
+
+static inline void keembay_timer_enable(void __iomem *base, u32 flags)
+{
+ writel(TIM_CONFIG_ENABLE | flags, base + TIM_CONFIG_OFFSET);
+}
+
+static inline void keembay_timer_disable(void __iomem *base)
+{
+ writel(0x0, base + TIM_CONFIG_OFFSET);
+}
+
+static inline void keembay_timer_update_counter(void __iomem *base, u32 val)
+{
+ writel(val, base + TIM_CNT_VAL_OFFSET);
+ writel(val, base + TIM_RELOAD_VAL_OFFSET);
+}
+
+static inline void keembay_timer_clear_pending_int(void __iomem *base)
+{
+ u32 val;
+
+ val = readl(base + TIM_CONFIG_OFFSET);
+ val &= ~TIM_CONFIG_INTERRUPT_PENDING;
+ writel(val, base + TIM_CONFIG_OFFSET);
+}
+
+static int keembay_timer_set_next_event(unsigned long evt, struct clock_event_device *ce)
+{
+ u32 flags = TIM_CONFIG_INTERRUPT_ENABLE;
+ struct timer_of *to = to_timer_of(ce);
+ void __iomem *tim_base = timer_of_base(to);
+
+ keembay_timer_disable(tim_base);
+ keembay_timer_update_counter(tim_base, evt);
+ keembay_timer_enable(tim_base, flags);
+
+ return 0;
+}
+
+static int keembay_timer_periodic(struct clock_event_device *ce)
+{
+ u32 flags = TIM_CONFIG_INTERRUPT_ENABLE | TIM_CONFIG_RESTART;
+ struct timer_of *to = to_timer_of(ce);
+ void __iomem *tim_base = timer_of_base(to);
+
+ keembay_timer_disable(tim_base);
+ keembay_timer_update_counter(tim_base, timer_of_period(to));
+ keembay_timer_enable(tim_base, flags);
+
+ return 0;
+}
+
+static int keembay_timer_shutdown(struct clock_event_device *ce)
+{
+ struct timer_of *to = to_timer_of(ce);
+
+ keembay_timer_disable(timer_of_base(to));
+
+ return 0;
+}
+
+static irqreturn_t keembay_timer_isr(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+ struct timer_of *to = to_timer_of(evt);
+ void __iomem *tim_base = timer_of_base(to);
+ u32 val;
+
+ val = readl(tim_base + TIM_CONFIG_OFFSET);
+
+ if (val & TIM_CONFIG_RESTART) {
+ /* Periodic Timer */
+ keembay_timer_clear_pending_int(tim_base);
+ } else {
+ /* One-Shot Timer */
+ keembay_timer_disable(tim_base);
+ }
+
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static struct timer_of keembay_ce_to = {
+ .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
+ .clkevt = {
+ .name = "keembay_sys_clkevt",
+ .cpumask = cpu_possible_mask,
+ .features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT |
+ CLOCK_EVT_FEAT_DYNIRQ,
+ .rating = TIM_RATING,
+ .set_next_event = keembay_timer_set_next_event,
+ .set_state_periodic = keembay_timer_periodic,
+ .set_state_shutdown = keembay_timer_shutdown,
+ },
+ .of_irq = {
+ .handler = keembay_timer_isr,
+ .flags = IRQF_TIMER,
+ },
+};
+
+static int __init keembay_clockevent_init(struct device_node *np)
+{
+ struct regmap *regmap;
+ int ret;
+ u32 val;
+
+ regmap = device_node_to_regmap(np->parent);
+ if (IS_ERR(regmap))
+ return PTR_ERR(regmap);
+
+ ret = regmap_read(regmap, TIM_CONFIG_OFFSET, &val);
+ if (ret)
+ return ret;
+
+ /* Prescaler bit must be enabled for the timer to function */
+ if (!(val & TIM_CONFIG_PRESCALER_ENABLE)) {
+ pr_err("%pOF: FW_BUG: Prescaler is not enabled\n", np);
+ ret = -ENODEV;
+ }
+
+
+ ret = timer_of_init(np, &keembay_ce_to);
+ if (ret)
+ return ret;
+
+ ret = regmap_read(regmap, TIM_RELOAD_VAL_OFFSET, &val);
+ if (ret)
+ return ret;
+
+ keembay_ce_to.of_clk.rate = keembay_ce_to.of_clk.rate / (val + 1);
+
+ clockevents_config_and_register(&keembay_ce_to.clkevt,
+ timer_of_rate(&keembay_ce_to),
+ 1,
+ U32_MAX);
+
+ return 0;
+}
+
+static struct timer_of keembay_cs_to = {
+ .flags = TIMER_OF_BASE | TIMER_OF_CLOCK,
+};
+
+static u64 notrace keembay_clocksource_read(struct clocksource *cs)
+{
+ return lo_hi_readq(timer_of_base(&keembay_cs_to));
+}
+
+static struct clocksource keembay_counter = {
+ .name = "keembay_sys_counter",
+ .rating = TIM_RATING,
+ .read = keembay_clocksource_read,
+ .mask = CLOCKSOURCE_MASK(TIM_CLKSRC_MASK_BITS),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS |
+ CLOCK_SOURCE_SUSPEND_NONSTOP,
+};
+
+static int __init keembay_clocksource_init(struct device_node *np)
+{
+ struct regmap *regmap;
+ u32 val;
+ int ret;
+
+ regmap = device_node_to_regmap(np->parent);
+ if (IS_ERR(regmap))
+ return PTR_ERR(regmap);
+
+ ret = regmap_read(regmap, TIM_CONFIG_OFFSET, &val);
+ if (ret)
+ return ret;
+
+ /* Free Running Counter bit must be enabled for counter to function */
+ if (!(val & TIM_CONFIG_COUNTER_ENABLE)) {
+ pr_err("%pOF: FW_BUG: free running counter is not enabled\n", np);
+ return -ENODEV;
+ }
+
+ ret = timer_of_init(np, &keembay_cs_to);
+ if (ret)
+ return ret;
+
+ return clocksource_register_hz(&keembay_counter, timer_of_rate(&keembay_cs_to));
+}
+
+TIMER_OF_DECLARE(keembay_clockevent, "intel,keembay-timer", keembay_clockevent_init);
+TIMER_OF_DECLARE(keembay_clocksource, "intel,keembay-counter", keembay_clocksource_init);
--
2.17.1
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