diff options
Diffstat (limited to 'arch/arm/plat-spear/time.c')
| -rw-r--r-- | arch/arm/plat-spear/time.c | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/arch/arm/plat-spear/time.c b/arch/arm/plat-spear/time.c new file mode 100644 index 00000000000..ab211652e4c --- /dev/null +++ b/arch/arm/plat-spear/time.c @@ -0,0 +1,259 @@ +/* + * arch/arm/plat-spear/time.c + * + * Copyright (C) 2009 ST Microelectronics + * Shiraz Hashim<shiraz.hashim@st.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/io.h> +#include <linux/kernel.h> +#include <linux/time.h> +#include <linux/irq.h> +#include <asm/mach/time.h> +#include <mach/irqs.h> +#include <mach/hardware.h> +#include <mach/spear.h> +#include <mach/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 void clockevent_set_mode(enum clock_event_mode mode, + struct clock_event_device *clk_event_dev); +static int clockevent_next_event(unsigned long evt, + struct clock_event_device *clk_event_dev); + +static cycle_t clocksource_read_cycles(struct clocksource *cs) +{ + return (cycle_t) readw(gpt_base + COUNT(CLKSRC)); +} + +static struct clocksource clksrc = { + .name = "tmr1", + .rating = 200, /* its a pretty decent clock */ + .read = clocksource_read_cycles, + .mask = 0xFFFF, /* 16 bits */ + .mult = 0, /* to be computed */ + .shift = 0, /* to be computed */ + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static void 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)); + + clocksource_calc_mult_shift(&clksrc, tick_rate, SPEAR_MIN_RANGE); + + /* register the clocksource */ + clocksource_register(&clksrc); +} + +static struct clock_event_device clkevt = { + .name = "tmr0", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_mode = clockevent_set_mode, + .set_next_event = clockevent_next_event, + .shift = 0, /* to be computed */ +}; + +static void clockevent_set_mode(enum clock_event_mode mode, + struct clock_event_device *clk_event_dev) +{ + u32 period; + u16 val; + + /* stop the timer */ + val = readw(gpt_base + CR(CLKEVT)); + val &= ~CTRL_ENABLE; + writew(val, gpt_base + CR(CLKEVT)); + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + 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)); + + break; + case CLOCK_EVT_MODE_ONESHOT: + val = readw(gpt_base + CR(CLKEVT)); + val |= CTRL_ONE_SHOT; + writew(val, gpt_base + CR(CLKEVT)); + + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_RESUME: + + break; + default: + pr_err("Invalid mode requested\n"); + break; + } +} + +static int clockevent_next_event(unsigned long cycles, + struct clock_event_device *clk_event_dev) +{ + u16 val; + + writew(cycles, gpt_base + LOAD(CLKEVT)); + + val = readw(gpt_base + CR(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 struct irqaction spear_timer_irq = { + .name = "timer", + .flags = IRQF_DISABLED | IRQF_TIMER, + .handler = spear_timer_interrupt +}; + +static void __init spear_clockevent_init(void) +{ + u32 tick_rate; + + /* program the prescaler */ + writew(CTRL_PRESCALER16, gpt_base + CR(CLKEVT)); + + tick_rate = clk_get_rate(gpt_clk); + tick_rate >>= CTRL_PRESCALER16; + + clockevents_calc_mult_shift(&clkevt, tick_rate, SPEAR_MIN_RANGE); + + clkevt.max_delta_ns = clockevent_delta2ns(0xfff0, + &clkevt); + clkevt.min_delta_ns = clockevent_delta2ns(3, &clkevt); + + clkevt.cpumask = cpumask_of(0); + + clockevents_register_device(&clkevt); + + setup_irq(SPEAR_GPT0_CHAN0_IRQ, &spear_timer_irq); +} + +void __init spear_setup_timer(void) +{ + struct clk *pll3_clk; + + if (!request_mem_region(SPEAR_GPT0_BASE, SZ_1K, "gpt0")) { + pr_err("%s:cannot get IO addr\n", __func__); + return; + } + + gpt_base = (void __iomem *)ioremap(SPEAR_GPT0_BASE, SZ_1K); + if (!gpt_base) { + pr_err("%s:ioremap failed for gpt\n", __func__); + goto err_mem; + } + + gpt_clk = clk_get_sys("gpt0", NULL); + if (!gpt_clk) { + pr_err("%s:couldn't get clk for gpt\n", __func__); + goto err_iomap; + } + + pll3_clk = clk_get(NULL, "pll3_48m_clk"); + if (!pll3_clk) { + pr_err("%s:couldn't get PLL3 as parent for gpt\n", __func__); + goto err_iomap; + } + + clk_set_parent(gpt_clk, pll3_clk); + + spear_clockevent_init(); + spear_clocksource_init(); + + return; + +err_iomap: + iounmap(gpt_base); + +err_mem: + release_mem_region(SPEAR_GPT0_BASE, SZ_1K); +} + +struct sys_timer spear_sys_timer = { + .init = spear_setup_timer, +}; |