diff options
Diffstat (limited to 'drivers/clocksource/mps2-timer.c')
| -rw-r--r-- | drivers/clocksource/mps2-timer.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/drivers/clocksource/mps2-timer.c b/drivers/clocksource/mps2-timer.c new file mode 100644 index 000000000..aa4d63af8 --- /dev/null +++ b/drivers/clocksource/mps2-timer.c @@ -0,0 +1,277 @@ +/* + * Copyright (C) 2015 ARM Limited + * + * Author: Vladimir Murzin <vladimir.murzin@arm.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/clk.h> +#include <linux/clockchips.h> +#include <linux/clocksource.h> +#include <linux/err.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/irq.h> +#include <linux/of_address.h> +#include <linux/of.h> +#include <linux/of_irq.h> +#include <linux/sched_clock.h> +#include <linux/slab.h> + +#define TIMER_CTRL 0x0 +#define TIMER_CTRL_ENABLE BIT(0) +#define TIMER_CTRL_IE BIT(3) + +#define TIMER_VALUE 0x4 +#define TIMER_RELOAD 0x8 +#define TIMER_INT 0xc + +struct clockevent_mps2 { + void __iomem *reg; + u32 clock_count_per_tick; + struct clock_event_device clkevt; +}; + +static void __iomem *sched_clock_base; + +static u64 notrace mps2_sched_read(void) +{ + return ~readl_relaxed(sched_clock_base + TIMER_VALUE); +} + +static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c) +{ + return container_of(c, struct clockevent_mps2, clkevt); +} + +static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset) +{ + writel_relaxed(val, to_mps2_clkevt(c)->reg + offset); +} + +static int mps2_timer_shutdown(struct clock_event_device *ce) +{ + clockevent_mps2_writel(0, ce, TIMER_RELOAD); + clockevent_mps2_writel(0, ce, TIMER_CTRL); + + return 0; +} + +static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce) +{ + clockevent_mps2_writel(next, ce, TIMER_VALUE); + clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL); + + return 0; +} + +static int mps2_timer_set_periodic(struct clock_event_device *ce) +{ + u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick; + + clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD); + clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE); + clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL); + + return 0; +} + +static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id) +{ + struct clockevent_mps2 *ce = dev_id; + u32 status = readl_relaxed(ce->reg + TIMER_INT); + + if (!status) { + pr_warn("spurious interrupt\n"); + return IRQ_NONE; + } + + writel_relaxed(1, ce->reg + TIMER_INT); + + ce->clkevt.event_handler(&ce->clkevt); + + return IRQ_HANDLED; +} + +static int __init mps2_clockevent_init(struct device_node *np) +{ + void __iomem *base; + struct clk *clk = NULL; + struct clockevent_mps2 *ce; + u32 rate; + int irq, ret; + const char *name = "mps2-clkevt"; + + ret = of_property_read_u32(np, "clock-frequency", &rate); + if (ret) { + clk = of_clk_get(np, 0); + if (IS_ERR(clk)) { + ret = PTR_ERR(clk); + pr_err("failed to get clock for clockevent: %d\n", ret); + goto out; + } + + ret = clk_prepare_enable(clk); + if (ret) { + pr_err("failed to enable clock for clockevent: %d\n", ret); + goto out_clk_put; + } + + rate = clk_get_rate(clk); + } + + base = of_iomap(np, 0); + if (!base) { + ret = -EADDRNOTAVAIL; + pr_err("failed to map register for clockevent: %d\n", ret); + goto out_clk_disable; + } + + irq = irq_of_parse_and_map(np, 0); + if (!irq) { + ret = -ENOENT; + pr_err("failed to get irq for clockevent: %d\n", ret); + goto out_iounmap; + } + + ce = kzalloc(sizeof(*ce), GFP_KERNEL); + if (!ce) { + ret = -ENOMEM; + goto out_iounmap; + } + + ce->reg = base; + ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ); + ce->clkevt.irq = irq; + ce->clkevt.name = name; + ce->clkevt.rating = 200; + ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; + ce->clkevt.cpumask = cpu_possible_mask; + ce->clkevt.set_state_shutdown = mps2_timer_shutdown, + ce->clkevt.set_state_periodic = mps2_timer_set_periodic, + ce->clkevt.set_state_oneshot = mps2_timer_shutdown, + ce->clkevt.set_next_event = mps2_timer_set_next_event; + + /* Ensure timer is disabled */ + writel_relaxed(0, base + TIMER_CTRL); + + ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce); + if (ret) { + pr_err("failed to request irq for clockevent: %d\n", ret); + goto out_kfree; + } + + clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff); + + return 0; + +out_kfree: + kfree(ce); +out_iounmap: + iounmap(base); +out_clk_disable: + /* clk_{disable, unprepare, put}() can handle NULL as a parameter */ + clk_disable_unprepare(clk); +out_clk_put: + clk_put(clk); +out: + return ret; +} + +static int __init mps2_clocksource_init(struct device_node *np) +{ + void __iomem *base; + struct clk *clk = NULL; + u32 rate; + int ret; + const char *name = "mps2-clksrc"; + + ret = of_property_read_u32(np, "clock-frequency", &rate); + if (ret) { + clk = of_clk_get(np, 0); + if (IS_ERR(clk)) { + ret = PTR_ERR(clk); + pr_err("failed to get clock for clocksource: %d\n", ret); + goto out; + } + + ret = clk_prepare_enable(clk); + if (ret) { + pr_err("failed to enable clock for clocksource: %d\n", ret); + goto out_clk_put; + } + + rate = clk_get_rate(clk); + } + + base = of_iomap(np, 0); + if (!base) { + ret = -EADDRNOTAVAIL; + pr_err("failed to map register for clocksource: %d\n", ret); + goto out_clk_disable; + } + + /* Ensure timer is disabled */ + writel_relaxed(0, base + TIMER_CTRL); + + /* ... and set it up as free-running clocksource */ + writel_relaxed(0xffffffff, base + TIMER_VALUE); + writel_relaxed(0xffffffff, base + TIMER_RELOAD); + + writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL); + + ret = clocksource_mmio_init(base + TIMER_VALUE, name, + rate, 200, 32, + clocksource_mmio_readl_down); + if (ret) { + pr_err("failed to init clocksource: %d\n", ret); + goto out_iounmap; + } + + sched_clock_base = base; + sched_clock_register(mps2_sched_read, 32, rate); + + return 0; + +out_iounmap: + iounmap(base); +out_clk_disable: + /* clk_{disable, unprepare, put}() can handle NULL as a parameter */ + clk_disable_unprepare(clk); +out_clk_put: + clk_put(clk); +out: + return ret; +} + +static int __init mps2_timer_init(struct device_node *np) +{ + static int has_clocksource, has_clockevent; + int ret; + + if (!has_clocksource) { + ret = mps2_clocksource_init(np); + if (!ret) { + has_clocksource = 1; + return 0; + } + } + + if (!has_clockevent) { + ret = mps2_clockevent_init(np); + if (!ret) { + has_clockevent = 1; + return 0; + } + } + + return 0; +} + +TIMER_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init); |