diff options
Diffstat (limited to 'drivers/clocksource/moxart_timer.c')
| -rw-r--r-- | drivers/clocksource/moxart_timer.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/drivers/clocksource/moxart_timer.c b/drivers/clocksource/moxart_timer.c new file mode 100644 index 000000000000..5eb2c35932b1 --- /dev/null +++ b/drivers/clocksource/moxart_timer.c @@ -0,0 +1,165 @@ +/* + * MOXA ART SoCs timer handling. + * + * Copyright (C) 2013 Jonas Jensen + * + * Jonas Jensen <jonas.jensen@gmail.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/clk.h> +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/irqreturn.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/io.h> +#include <linux/clocksource.h> +#include <linux/bitops.h> + +#define TIMER1_BASE 0x00 +#define TIMER2_BASE 0x10 +#define TIMER3_BASE 0x20 + +#define REG_COUNT 0x0 /* writable */ +#define REG_LOAD 0x4 +#define REG_MATCH1 0x8 +#define REG_MATCH2 0xC + +#define TIMER_CR 0x30 +#define TIMER_INTR_STATE 0x34 +#define TIMER_INTR_MASK 0x38 + +/* + * TIMER_CR flags: + * + * TIMEREG_CR_*_CLOCK 0: PCLK, 1: EXT1CLK + * TIMEREG_CR_*_INT overflow interrupt enable bit + */ +#define TIMEREG_CR_1_ENABLE BIT(0) +#define TIMEREG_CR_1_CLOCK BIT(1) +#define TIMEREG_CR_1_INT BIT(2) +#define TIMEREG_CR_2_ENABLE BIT(3) +#define TIMEREG_CR_2_CLOCK BIT(4) +#define TIMEREG_CR_2_INT BIT(5) +#define TIMEREG_CR_3_ENABLE BIT(6) +#define TIMEREG_CR_3_CLOCK BIT(7) +#define TIMEREG_CR_3_INT BIT(8) +#define TIMEREG_CR_COUNT_UP BIT(9) + +#define TIMER1_ENABLE (TIMEREG_CR_2_ENABLE | TIMEREG_CR_1_ENABLE) +#define TIMER1_DISABLE (TIMEREG_CR_2_ENABLE) + +static void __iomem *base; +static unsigned int clock_count_per_tick; + +static void moxart_clkevt_mode(enum clock_event_mode mode, + struct clock_event_device *clk) +{ + switch (mode) { + case CLOCK_EVT_MODE_RESUME: + case CLOCK_EVT_MODE_ONESHOT: + writel(TIMER1_DISABLE, base + TIMER_CR); + writel(~0, base + TIMER1_BASE + REG_LOAD); + break; + case CLOCK_EVT_MODE_PERIODIC: + writel(clock_count_per_tick, base + TIMER1_BASE + REG_LOAD); + writel(TIMER1_ENABLE, base + TIMER_CR); + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + default: + writel(TIMER1_DISABLE, base + TIMER_CR); + break; + } +} + +static int moxart_clkevt_next_event(unsigned long cycles, + struct clock_event_device *unused) +{ + u32 u; + + writel(TIMER1_DISABLE, base + TIMER_CR); + + u = readl(base + TIMER1_BASE + REG_COUNT) - cycles; + writel(u, base + TIMER1_BASE + REG_MATCH1); + + writel(TIMER1_ENABLE, base + TIMER_CR); + + return 0; +} + +static struct clock_event_device moxart_clockevent = { + .name = "moxart_timer", + .rating = 200, + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_mode = moxart_clkevt_mode, + .set_next_event = moxart_clkevt_next_event, +}; + +static irqreturn_t moxart_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + evt->event_handler(evt); + return IRQ_HANDLED; +} + +static struct irqaction moxart_timer_irq = { + .name = "moxart-timer", + .flags = IRQF_TIMER, + .handler = moxart_timer_interrupt, + .dev_id = &moxart_clockevent, +}; + +static void __init moxart_timer_init(struct device_node *node) +{ + int ret, irq; + unsigned long pclk; + struct clk *clk; + + base = of_iomap(node, 0); + if (!base) + panic("%s: of_iomap failed\n", node->full_name); + + irq = irq_of_parse_and_map(node, 0); + if (irq <= 0) + panic("%s: irq_of_parse_and_map failed\n", node->full_name); + + ret = setup_irq(irq, &moxart_timer_irq); + if (ret) + panic("%s: setup_irq failed\n", node->full_name); + + clk = of_clk_get(node, 0); + if (IS_ERR(clk)) + panic("%s: of_clk_get failed\n", node->full_name); + + pclk = clk_get_rate(clk); + + if (clocksource_mmio_init(base + TIMER2_BASE + REG_COUNT, + "moxart_timer", pclk, 200, 32, + clocksource_mmio_readl_down)) + panic("%s: clocksource_mmio_init failed\n", node->full_name); + + clock_count_per_tick = DIV_ROUND_CLOSEST(pclk, HZ); + + writel(~0, base + TIMER2_BASE + REG_LOAD); + writel(TIMEREG_CR_2_ENABLE, base + TIMER_CR); + + moxart_clockevent.cpumask = cpumask_of(0); + moxart_clockevent.irq = irq; + + /* + * documentation is not publicly available: + * min_delta / max_delta obtained by trial-and-error, + * max_delta 0xfffffffe should be ok because count + * register size is u32 + */ + clockevents_config_and_register(&moxart_clockevent, pclk, + 0x4, 0xfffffffe); +} +CLOCKSOURCE_OF_DECLARE(moxart, "moxa,moxart-timer", moxart_timer_init); |