--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IXP4 timer driver
+ * Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * Based on arch/arm/mach-ixp4xx/common.c
+ * Copyright 2002 (C) Intel Corporation
+ * Copyright 2003-2004 (C) MontaVista, Software, Inc.
+ * Copyright (C) Deepak Saxena <dsaxena@plexity.net>
+ */
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+/* Goes away with OF conversion */
+#include <linux/platform_data/timer-ixp4xx.h>
+
+/*
+ * Constants to make it easy to access Timer Control/Status registers
+ */
+#define IXP4XX_OSTS_OFFSET 0x00 /* Continuous Timestamp */
+#define IXP4XX_OST1_OFFSET 0x04 /* Timer 1 Timestamp */
+#define IXP4XX_OSRT1_OFFSET 0x08 /* Timer 1 Reload */
+#define IXP4XX_OST2_OFFSET 0x0C /* Timer 2 Timestamp */
+#define IXP4XX_OSRT2_OFFSET 0x10 /* Timer 2 Reload */
+#define IXP4XX_OSWT_OFFSET 0x14 /* Watchdog Timer */
+#define IXP4XX_OSWE_OFFSET 0x18 /* Watchdog Enable */
+#define IXP4XX_OSWK_OFFSET 0x1C /* Watchdog Key */
+#define IXP4XX_OSST_OFFSET 0x20 /* Timer Status */
+
+/*
+ * Timer register values and bit definitions
+ */
+#define IXP4XX_OST_ENABLE 0x00000001
+#define IXP4XX_OST_ONE_SHOT 0x00000002
+/* Low order bits of reload value ignored */
+#define IXP4XX_OST_RELOAD_MASK 0x00000003
+#define IXP4XX_OST_DISABLED 0x00000000
+#define IXP4XX_OSST_TIMER_1_PEND 0x00000001
+#define IXP4XX_OSST_TIMER_2_PEND 0x00000002
+#define IXP4XX_OSST_TIMER_TS_PEND 0x00000004
+#define IXP4XX_OSST_TIMER_WDOG_PEND 0x00000008
+#define IXP4XX_OSST_TIMER_WARM_RESET 0x00000010
+
+#define IXP4XX_WDT_KEY 0x0000482E
+#define IXP4XX_WDT_RESET_ENABLE 0x00000001
+#define IXP4XX_WDT_IRQ_ENABLE 0x00000002
+#define IXP4XX_WDT_COUNT_ENABLE 0x00000004
+
+struct ixp4xx_timer {
+ void __iomem *base;
+ unsigned int tick_rate;
+ u32 latch;
+ struct clock_event_device clkevt;
+#ifdef CONFIG_ARM
+ struct delay_timer delay_timer;
+#endif
+};
+
+/*
+ * A local singleton used by sched_clock and delay timer reads, which are
+ * fast and stateless
+ */
+static struct ixp4xx_timer *local_ixp4xx_timer;
+
+static inline struct ixp4xx_timer *
+to_ixp4xx_timer(struct clock_event_device *evt)
+{
+ return container_of(evt, struct ixp4xx_timer, clkevt);
+}
+
+static u64 notrace ixp4xx_read_sched_clock(void)
+{
+ return __raw_readl(local_ixp4xx_timer->base + IXP4XX_OSTS_OFFSET);
+}
+
+static u64 ixp4xx_clocksource_read(struct clocksource *c)
+{
+ return __raw_readl(local_ixp4xx_timer->base + IXP4XX_OSTS_OFFSET);
+}
+
+static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id)
+{
+ struct ixp4xx_timer *tmr = dev_id;
+ struct clock_event_device *evt = &tmr->clkevt;
+
+ /* Clear Pending Interrupt */
+ __raw_writel(IXP4XX_OSST_TIMER_1_PEND,
+ tmr->base + IXP4XX_OSST_OFFSET);
+
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static int ixp4xx_set_next_event(unsigned long cycles,
+ struct clock_event_device *evt)
+{
+ struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+ u32 val;
+
+ val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
+ /* Keep enable/oneshot bits */
+ val &= IXP4XX_OST_RELOAD_MASK;
+ __raw_writel((cycles & ~IXP4XX_OST_RELOAD_MASK) | val,
+ tmr->base + IXP4XX_OSRT1_OFFSET);
+
+ return 0;
+}
+
+static int ixp4xx_shutdown(struct clock_event_device *evt)
+{
+ struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+ u32 val;
+
+ val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
+ val &= ~IXP4XX_OST_ENABLE;
+ __raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+ return 0;
+}
+
+static int ixp4xx_set_oneshot(struct clock_event_device *evt)
+{
+ struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+
+ __raw_writel(IXP4XX_OST_ENABLE | IXP4XX_OST_ONE_SHOT,
+ tmr->base + IXP4XX_OSRT1_OFFSET);
+
+ return 0;
+}
+
+static int ixp4xx_set_periodic(struct clock_event_device *evt)
+{
+ struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+ u32 val;
+
+ val = tmr->latch & ~IXP4XX_OST_RELOAD_MASK;
+ val |= IXP4XX_OST_ENABLE;
+ __raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+ return 0;
+}
+
+static int ixp4xx_resume(struct clock_event_device *evt)
+{
+ struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+ u32 val;
+
+ val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
+ val |= IXP4XX_OST_ENABLE;
+ __raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+ return 0;
+}
+
+/*
+ * IXP4xx timer tick
+ * We use OS timer1 on the CPU for the timer tick and the timestamp
+ * counter as a source of real clock ticks to account for missed jiffies.
+ */
+static __init int ixp4xx_timer_register(void __iomem *base,
+ int timer_irq,
+ unsigned int timer_freq)
+{
+ struct ixp4xx_timer *tmr;
+ int ret;
+
+ tmr = kzalloc(sizeof(*tmr), GFP_KERNEL);
+ if (!tmr)
+ return -ENOMEM;
+ tmr->base = base;
+ tmr->tick_rate = timer_freq;
+
+ /*
+ * The timer register doesn't allow to specify the two least
+ * significant bits of the timeout value and assumes them being zero.
+ * So make sure the latch is the best value with the two least
+ * significant bits unset.
+ */
+ tmr->latch = DIV_ROUND_CLOSEST(timer_freq,
+ (IXP4XX_OST_RELOAD_MASK + 1) * HZ)
+ * (IXP4XX_OST_RELOAD_MASK + 1);
+
+ local_ixp4xx_timer = tmr;
+
+ /* Reset/disable counter */
+ __raw_writel(0, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+ /* Clear any pending interrupt on timer 1 */
+ __raw_writel(IXP4XX_OSST_TIMER_1_PEND,
+ tmr->base + IXP4XX_OSST_OFFSET);
+
+ /* Reset time-stamp counter */
+ __raw_writel(0, tmr->base + IXP4XX_OSTS_OFFSET);
+
+ clocksource_mmio_init(NULL, "OSTS", timer_freq, 200, 32,
+ ixp4xx_clocksource_read);
+
+ tmr->clkevt.name = "ixp4xx timer1";
+ tmr->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+ tmr->clkevt.rating = 200;
+ tmr->clkevt.set_state_shutdown = ixp4xx_shutdown;
+ tmr->clkevt.set_state_periodic = ixp4xx_set_periodic;
+ tmr->clkevt.set_state_oneshot = ixp4xx_set_oneshot;
+ tmr->clkevt.tick_resume = ixp4xx_resume;
+ tmr->clkevt.set_next_event = ixp4xx_set_next_event;
+ tmr->clkevt.cpumask = cpumask_of(0);
+ tmr->clkevt.irq = timer_irq;
+ ret = request_irq(timer_irq, ixp4xx_timer_interrupt,
+ IRQF_TIMER, "IXP4XX-TIMER1", tmr);
+ if (ret) {
+ pr_crit("no timer IRQ\n");
+ return -ENODEV;
+ }
+ clockevents_config_and_register(&tmr->clkevt, timer_freq,
+ 0xf, 0xfffffffe);
+
+#ifdef CONFIG_ARM
+ sched_clock_register(ixp4xx_read_sched_clock, 32, timer_freq);
+#endif
+
+ return 0;
+}
+
+/**
+ * ixp4xx_timer_setup() - Timer setup function to be called from boardfiles
+ * @timerbase: physical base of timer block
+ * @timer_irq: Linux IRQ number for the timer
+ * @timer_freq: Fixed frequency of the timer
+ */
+void __init ixp4xx_timer_setup(resource_size_t timerbase,
+ int timer_irq,
+ unsigned int timer_freq)
+{
+ void __iomem *base;
+
+ base = ioremap(timerbase, 0x100);
+ if (!base) {
+ pr_crit("IXP4xx: can't remap timer\n");
+ return;
+ }
+ ixp4xx_timer_register(base, timer_irq, timer_freq);
+}
+EXPORT_SYMBOL_GPL(ixp4xx_timer_setup);
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