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Diffstat (limited to 'arch/arm/mach-spear/time.c')
| -rw-r--r-- | arch/arm/mach-spear/time.c | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/arch/arm/mach-spear/time.c b/arch/arm/mach-spear/time.c new file mode 100644 index 000000000..d1fdb6066 --- /dev/null +++ b/arch/arm/mach-spear/time.c @@ -0,0 +1,251 @@ +/* + * arch/arm/plat-spear/time.c + * + * Copyright (C) 2010 ST Microelectronics + * Shiraz Hashim<shiraz.linux.kernel@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/clocksource.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/ioport.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/of_irq.h> +#include <linux/of_address.h> +#include <linux/time.h> +#include <linux/irq.h> +#include <asm/mach/time.h> +#include "generic.h" + +/* + * We would use TIMER0 and TIMER1 as clockevent and clocksource. + * Timer0 and Timer1 both belong to same gpt block in cpu subbsystem. Further + * they share same functional clock. Any change in one's functional clock will + * also affect other timer. + */ + +#define CLKEVT 0 /* gpt0, channel0 as clockevent */ +#define CLKSRC 1 /* gpt0, channel1 as clocksource */ + +/* Register offsets, x is channel number */ +#define CR(x) ((x) * 0x80 + 0x80) +#define IR(x) ((x) * 0x80 + 0x84) +#define LOAD(x) ((x) * 0x80 + 0x88) +#define COUNT(x) ((x) * 0x80 + 0x8C) + +/* Reg bit definitions */ +#define CTRL_INT_ENABLE 0x0100 +#define CTRL_ENABLE 0x0020 +#define CTRL_ONE_SHOT 0x0010 + +#define CTRL_PRESCALER1 0x0 +#define CTRL_PRESCALER2 0x1 +#define CTRL_PRESCALER4 0x2 +#define CTRL_PRESCALER8 0x3 +#define CTRL_PRESCALER16 0x4 +#define CTRL_PRESCALER32 0x5 +#define CTRL_PRESCALER64 0x6 +#define CTRL_PRESCALER128 0x7 +#define CTRL_PRESCALER256 0x8 + +#define INT_STATUS 0x1 + +/* + * Minimum clocksource/clockevent timer range in seconds + */ +#define SPEAR_MIN_RANGE 4 + +static __iomem void *gpt_base; +static struct clk *gpt_clk; + +static int clockevent_next_event(unsigned long evt, + struct clock_event_device *clk_event_dev); + +static void __init spear_clocksource_init(void) +{ + u32 tick_rate; + u16 val; + + /* program the prescaler (/256)*/ + writew(CTRL_PRESCALER256, gpt_base + CR(CLKSRC)); + + /* find out actual clock driving Timer */ + tick_rate = clk_get_rate(gpt_clk); + tick_rate >>= CTRL_PRESCALER256; + + writew(0xFFFF, gpt_base + LOAD(CLKSRC)); + + val = readw(gpt_base + CR(CLKSRC)); + val &= ~CTRL_ONE_SHOT; /* autoreload mode */ + val |= CTRL_ENABLE ; + writew(val, gpt_base + CR(CLKSRC)); + + /* register the clocksource */ + clocksource_mmio_init(gpt_base + COUNT(CLKSRC), "tmr1", tick_rate, + 200, 16, clocksource_mmio_readw_up); +} + +static inline void timer_shutdown(struct clock_event_device *evt) +{ + u16 val = readw(gpt_base + CR(CLKEVT)); + + /* stop the timer */ + val &= ~CTRL_ENABLE; + writew(val, gpt_base + CR(CLKEVT)); +} + +static int spear_shutdown(struct clock_event_device *evt) +{ + timer_shutdown(evt); + + return 0; +} + +static int spear_set_oneshot(struct clock_event_device *evt) +{ + u16 val; + + /* stop the timer */ + timer_shutdown(evt); + + val = readw(gpt_base + CR(CLKEVT)); + val |= CTRL_ONE_SHOT; + writew(val, gpt_base + CR(CLKEVT)); + + return 0; +} + +static int spear_set_periodic(struct clock_event_device *evt) +{ + u32 period; + u16 val; + + /* stop the timer */ + timer_shutdown(evt); + + period = clk_get_rate(gpt_clk) / HZ; + period >>= CTRL_PRESCALER16; + writew(period, gpt_base + LOAD(CLKEVT)); + + val = readw(gpt_base + CR(CLKEVT)); + val &= ~CTRL_ONE_SHOT; + val |= CTRL_ENABLE | CTRL_INT_ENABLE; + writew(val, gpt_base + CR(CLKEVT)); + + return 0; +} + +static struct clock_event_device clkevt = { + .name = "tmr0", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_state_shutdown = spear_shutdown, + .set_state_periodic = spear_set_periodic, + .set_state_oneshot = spear_set_oneshot, + .tick_resume = spear_shutdown, + .set_next_event = clockevent_next_event, + .shift = 0, /* to be computed */ +}; + +static int clockevent_next_event(unsigned long cycles, + struct clock_event_device *clk_event_dev) +{ + u16 val = readw(gpt_base + CR(CLKEVT)); + + if (val & CTRL_ENABLE) + writew(val & ~CTRL_ENABLE, gpt_base + CR(CLKEVT)); + + writew(cycles, gpt_base + LOAD(CLKEVT)); + + val |= CTRL_ENABLE | CTRL_INT_ENABLE; + writew(val, gpt_base + CR(CLKEVT)); + + return 0; +} + +static irqreturn_t spear_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = &clkevt; + + writew(INT_STATUS, gpt_base + IR(CLKEVT)); + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static void __init spear_clockevent_init(int irq) +{ + u32 tick_rate; + + /* program the prescaler */ + writew(CTRL_PRESCALER16, gpt_base + CR(CLKEVT)); + + tick_rate = clk_get_rate(gpt_clk); + tick_rate >>= CTRL_PRESCALER16; + + clkevt.cpumask = cpumask_of(0); + + clockevents_config_and_register(&clkevt, tick_rate, 3, 0xfff0); + + if (request_irq(irq, spear_timer_interrupt, IRQF_TIMER, "timer", NULL)) + pr_err("Failed to request irq %d (timer)\n", irq); +} + +static const struct of_device_id timer_of_match[] __initconst = { + { .compatible = "st,spear-timer", }, + { }, +}; + +void __init spear_setup_of_timer(void) +{ + struct device_node *np; + int irq, ret; + + np = of_find_matching_node(NULL, timer_of_match); + if (!np) { + pr_err("%s: No timer passed via DT\n", __func__); + return; + } + + irq = irq_of_parse_and_map(np, 0); + if (!irq) { + pr_err("%s: No irq passed for timer via DT\n", __func__); + return; + } + + gpt_base = of_iomap(np, 0); + if (!gpt_base) { + pr_err("%s: of iomap failed\n", __func__); + return; + } + + gpt_clk = clk_get_sys("gpt0", NULL); + if (IS_ERR(gpt_clk)) { + pr_err("%s:couldn't get clk for gpt\n", __func__); + goto err_iomap; + } + + ret = clk_prepare_enable(gpt_clk); + if (ret < 0) { + pr_err("%s:couldn't prepare-enable gpt clock\n", __func__); + goto err_prepare_enable_clk; + } + + spear_clockevent_init(irq); + spear_clocksource_init(); + + return; + +err_prepare_enable_clk: + clk_put(gpt_clk); +err_iomap: + iounmap(gpt_base); +} |