diff options
Diffstat (limited to 'drivers/clocksource/nomadik-mtu.c')
| -rw-r--r-- | drivers/clocksource/nomadik-mtu.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/drivers/clocksource/nomadik-mtu.c b/drivers/clocksource/nomadik-mtu.c new file mode 100644 index 000000000000..23c780ba0d35 --- /dev/null +++ b/drivers/clocksource/nomadik-mtu.c @@ -0,0 +1,224 @@ +/* + * Copyright (C) 2008 STMicroelectronics + * Copyright (C) 2010 Alessandro Rubini + * Copyright (C) 2010 Linus Walleij for ST-Ericsson + * + * 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. + */ +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/io.h> +#include <linux/clockchips.h> +#include <linux/clocksource.h> +#include <linux/clk.h> +#include <linux/jiffies.h> +#include <linux/err.h> +#include <linux/platform_data/clocksource-nomadik-mtu.h> +#include <asm/mach/time.h> +#include <asm/sched_clock.h> + +/* + * The MTU device hosts four different counters, with 4 set of + * registers. These are register names. + */ + +#define MTU_IMSC 0x00 /* Interrupt mask set/clear */ +#define MTU_RIS 0x04 /* Raw interrupt status */ +#define MTU_MIS 0x08 /* Masked interrupt status */ +#define MTU_ICR 0x0C /* Interrupt clear register */ + +/* per-timer registers take 0..3 as argument */ +#define MTU_LR(x) (0x10 + 0x10 * (x) + 0x00) /* Load value */ +#define MTU_VAL(x) (0x10 + 0x10 * (x) + 0x04) /* Current value */ +#define MTU_CR(x) (0x10 + 0x10 * (x) + 0x08) /* Control reg */ +#define MTU_BGLR(x) (0x10 + 0x10 * (x) + 0x0c) /* At next overflow */ + +/* bits for the control register */ +#define MTU_CRn_ENA 0x80 +#define MTU_CRn_PERIODIC 0x40 /* if 0 = free-running */ +#define MTU_CRn_PRESCALE_MASK 0x0c +#define MTU_CRn_PRESCALE_1 0x00 +#define MTU_CRn_PRESCALE_16 0x04 +#define MTU_CRn_PRESCALE_256 0x08 +#define MTU_CRn_32BITS 0x02 +#define MTU_CRn_ONESHOT 0x01 /* if 0 = wraps reloading from BGLR*/ + +/* Other registers are usual amba/primecell registers, currently not used */ +#define MTU_ITCR 0xff0 +#define MTU_ITOP 0xff4 + +#define MTU_PERIPH_ID0 0xfe0 +#define MTU_PERIPH_ID1 0xfe4 +#define MTU_PERIPH_ID2 0xfe8 +#define MTU_PERIPH_ID3 0xfeC + +#define MTU_PCELL0 0xff0 +#define MTU_PCELL1 0xff4 +#define MTU_PCELL2 0xff8 +#define MTU_PCELL3 0xffC + +static void __iomem *mtu_base; +static bool clkevt_periodic; +static u32 clk_prescale; +static u32 nmdk_cycle; /* write-once */ + +#ifdef CONFIG_NOMADIK_MTU_SCHED_CLOCK +/* + * Override the global weak sched_clock symbol with this + * local implementation which uses the clocksource to get some + * better resolution when scheduling the kernel. + */ +static u32 notrace nomadik_read_sched_clock(void) +{ + if (unlikely(!mtu_base)) + return 0; + + return -readl(mtu_base + MTU_VAL(0)); +} +#endif + +/* Clockevent device: use one-shot mode */ +static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev) +{ + writel(1 << 1, mtu_base + MTU_IMSC); + writel(evt, mtu_base + MTU_LR(1)); + /* Load highest value, enable device, enable interrupts */ + writel(MTU_CRn_ONESHOT | clk_prescale | + MTU_CRn_32BITS | MTU_CRn_ENA, + mtu_base + MTU_CR(1)); + + return 0; +} + +void nmdk_clkevt_reset(void) +{ + if (clkevt_periodic) { + /* Timer: configure load and background-load, and fire it up */ + writel(nmdk_cycle, mtu_base + MTU_LR(1)); + writel(nmdk_cycle, mtu_base + MTU_BGLR(1)); + + writel(MTU_CRn_PERIODIC | clk_prescale | + MTU_CRn_32BITS | MTU_CRn_ENA, + mtu_base + MTU_CR(1)); + writel(1 << 1, mtu_base + MTU_IMSC); + } else { + /* Generate an interrupt to start the clockevent again */ + (void) nmdk_clkevt_next(nmdk_cycle, NULL); + } +} + +static void nmdk_clkevt_mode(enum clock_event_mode mode, + struct clock_event_device *dev) +{ + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + clkevt_periodic = true; + nmdk_clkevt_reset(); + break; + case CLOCK_EVT_MODE_ONESHOT: + clkevt_periodic = false; + break; + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + writel(0, mtu_base + MTU_IMSC); + /* disable timer */ + writel(0, mtu_base + MTU_CR(1)); + /* load some high default value */ + writel(0xffffffff, mtu_base + MTU_LR(1)); + break; + case CLOCK_EVT_MODE_RESUME: + break; + } +} + +static struct clock_event_device nmdk_clkevt = { + .name = "mtu_1", + .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC, + .rating = 200, + .set_mode = nmdk_clkevt_mode, + .set_next_event = nmdk_clkevt_next, +}; + +/* + * IRQ Handler for timer 1 of the MTU block. + */ +static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evdev = dev_id; + + writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */ + evdev->event_handler(evdev); + return IRQ_HANDLED; +} + +static struct irqaction nmdk_timer_irq = { + .name = "Nomadik Timer Tick", + .flags = IRQF_DISABLED | IRQF_TIMER, + .handler = nmdk_timer_interrupt, + .dev_id = &nmdk_clkevt, +}; + +void nmdk_clksrc_reset(void) +{ + /* Disable */ + writel(0, mtu_base + MTU_CR(0)); + + /* ClockSource: configure load and background-load, and fire it up */ + writel(nmdk_cycle, mtu_base + MTU_LR(0)); + writel(nmdk_cycle, mtu_base + MTU_BGLR(0)); + + writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA, + mtu_base + MTU_CR(0)); +} + +void __init nmdk_timer_init(void __iomem *base, int irq) +{ + unsigned long rate; + struct clk *clk0; + + mtu_base = base; + clk0 = clk_get_sys("mtu0", NULL); + BUG_ON(IS_ERR(clk0)); + BUG_ON(clk_prepare(clk0) < 0); + BUG_ON(clk_enable(clk0) < 0); + + /* + * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz + * for ux500. + * Use a divide-by-16 counter if the tick rate is more than 32MHz. + * At 32 MHz, the timer (with 32 bit counter) can be programmed + * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer + * with 16 gives too low timer resolution. + */ + rate = clk_get_rate(clk0); + if (rate > 32000000) { + rate /= 16; + clk_prescale = MTU_CRn_PRESCALE_16; + } else { + clk_prescale = MTU_CRn_PRESCALE_1; + } + + /* Cycles for periodic mode */ + nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ); + + + /* Timer 0 is the free running clocksource */ + nmdk_clksrc_reset(); + + if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0", + rate, 200, 32, clocksource_mmio_readl_down)) + pr_err("timer: failed to initialize clock source %s\n", + "mtu_0"); + +#ifdef CONFIG_NOMADIK_MTU_SCHED_CLOCK + setup_sched_clock(nomadik_read_sched_clock, 32, rate); +#endif + + /* Timer 1 is used for events, register irq and clockevents */ + setup_irq(irq, &nmdk_timer_irq); + nmdk_clkevt.cpumask = cpumask_of(0); + clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU); +} |