diff options
Diffstat (limited to 'arch/arm/mach-ux500/pm/timer.c')
| -rw-r--r-- | arch/arm/mach-ux500/pm/timer.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/arm/mach-ux500/pm/timer.c b/arch/arm/mach-ux500/pm/timer.c new file mode 100644 index 00000000000..61f92bf73da --- /dev/null +++ b/arch/arm/mach-ux500/pm/timer.c @@ -0,0 +1,193 @@ +/* + * Copyright (C) ST-Ericsson SA 2010-2011 + * + * Author: Jonas Aaberg <jonas.aberg@stericsson.com> for ST-Ericsson + * + * License Terms: GNU General Public License v2 + * + * The RTC timer block is a ST Microelectronics variant of ARM PL031. + * Clockwatch part is the same as PL031, while the timer part is only + * present on the ST Microelectronics variant. + * Here only the timer part is used. + * + * The timer part is quite troublesome to program correctly. Lots + * of long delays must be there in order to secure that you actually get what + * you wrote. + * + * In other words, this timer is and should only used from cpuidle during + * special conditions when the surroundings are know in order to be able + * to remove the number of delays. + */ +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/ktime.h> +#include <linux/delay.h> + +#include <asm/errno.h> + +#include <mach/hardware.h> + +#define RTC_IMSC 0x10 +#define RTC_MIS 0x18 +#define RTC_ICR 0x1C +#define RTC_TDR 0x20 +#define RTC_TLR1 0x24 +#define RTC_TCR 0x28 + +#define RTC_TLR2 0x2C +#define RTC_TPR1 0x3C + +#define RTC_TCR_RTTOS (1 << 0) +#define RTC_TCR_RTTEN (1 << 1) +#define RTC_TCR_RTTSS (1 << 2) + +#define RTC_IMSC_TIMSC (1 << 1) +#define RTC_ICR_TIC (1 << 1) +#define RTC_MIS_RTCTMIS (1 << 1) + +#define RTC_TCR_RTTPS_2 (1 << 4) +#define RTC_TCR_RTTPS_3 (2 << 4) +#define RTC_TCR_RTTPS_4 (3 << 4) +#define RTC_TCR_RTTPS_5 (4 << 4) +#define RTC_TCR_RTTPS_6 (5 << 4) +#define RTC_TCR_RTTPS_7 (6 << 4) +#define RTC_TCR_RTTPS_8 (7 << 4) + +#define WRITE_DELAY 130 /* 4 cycles plus margin */ + +/* + * Count down measure point. It just have to be high to differ + * from scheduled values. + */ +#define MEASURE_VAL 0xffffffff + +/* Just a value bigger than any reason able scheduled timeout. */ +#define MEASURE_VAL_LIMIT 0xf0000000 + +#define TICKS_TO_NS(x) ((s64)x * 30518) +#define US_TO_TICKS(x) ((u32)((1000 * x) / 30518)) + +static void __iomem *rtc_base; +static bool measure_latency; + +#ifdef CONFIG_UX500_CPUIDLE_DEBUG + +/* + * The plan here is to be able to measure the ApSleep/ApDeepSleep exit latency + * by having a know timer pattern. + * The first entry in the pattern, LR1, is the value that the scheduler + * wants us to sleep. The second pattern in a high value, too large to be + * scheduled, so we can differ between a running scheduled value and a + * time measure value. + * When a RTT interrupt has occured, the block will automatically start + * to execute the measure value in LR2 and when the ARM is awake, it reads + * how far the RTT has decreased the value loaded from LR2 and from that + * calculate how long time it took to wake up. + */ +ktime_t u8500_rtc_exit_latency_get(void) +{ + u32 ticks; + + if (measure_latency) { + ticks = MEASURE_VAL - readl(rtc_base + RTC_TDR); + + /* + * Check if we are actually counting on a LR2 value. + * If not we have woken on another interrupt. + */ + if (ticks < MEASURE_VAL_LIMIT) { + /* convert 32 kHz ticks to ns */ + return ktime_set(0, TICKS_TO_NS(ticks)); + } + } + return ktime_set(0, 0); +} + +static void measure_latency_start(void) +{ + udelay(WRITE_DELAY); + /* + * Disable RTT and clean self-start due to we want to restart, + * not continue from current pattern. (See below) + */ + writel(0, rtc_base + RTC_TCR); + udelay(WRITE_DELAY); + + /* + * Program LR2 (load register two) to maximum value to ease + * identification of timer interrupt vs other. + */ + writel(MEASURE_VAL, rtc_base + RTC_TLR2); + /* + * Set Load Register execution pattern, bit clear + * means pick LR1, bit set means LR2 + * 0xfe, binary 11111110 means first do LR1 then do + * LR2 seven times + */ + writel(0xfe, rtc_base + RTC_TPR1); + + udelay(WRITE_DELAY); + + /* + * Enable self-start, plus a pattern of eight. + */ + writel(RTC_TCR_RTTSS | RTC_TCR_RTTPS_8, + rtc_base + RTC_TCR); + udelay(WRITE_DELAY); +} + +void ux500_rtcrtt_measure_latency(bool enable) +{ + if (enable) { + measure_latency_start(); + } else { + writel(RTC_TCR_RTTSS | RTC_TCR_RTTOS, rtc_base + RTC_TCR); + writel(RTC_ICR_TIC, rtc_base + RTC_ICR); + writel(RTC_IMSC_TIMSC, rtc_base + RTC_IMSC); + } + measure_latency = enable; +} +#else +static inline void measure_latency_start(void) { } +static inline void ux500_rtcrtt_measure_latency(bool enable) +{ + writel(RTC_TCR_RTTSS | RTC_TCR_RTTOS, rtc_base + RTC_TCR); + writel(RTC_ICR_TIC, rtc_base + RTC_ICR); + writel(RTC_IMSC_TIMSC, rtc_base + RTC_IMSC); +} +#endif + +void ux500_rtcrtt_off(void) +{ + if (measure_latency) { + measure_latency_start(); + } else { + /* Clear eventual interrupts */ + if (readl(rtc_base + RTC_MIS) & RTC_MIS_RTCTMIS) + writel(RTC_ICR_TIC, rtc_base + RTC_ICR); + + /* Disable, self start and oneshot mode */ + writel(RTC_TCR_RTTSS | RTC_TCR_RTTOS, rtc_base + RTC_TCR); + } +} + +void ux500_rtcrtt_next(u32 time_us) +{ + writel(US_TO_TICKS(time_us), rtc_base + RTC_TLR1); +} + +static int __init ux500_rtcrtt_init(void) +{ + if (cpu_is_u8500()) { + rtc_base = __io_address(U8500_RTC_BASE); + } else if (cpu_is_u5500()) { + rtc_base = __io_address(U5500_RTC_BASE); + } else { + pr_err("timer-rtt: Unknown DB Asic!\n"); + return -EINVAL; + } + ux500_rtcrtt_measure_latency(false); + return 0; +} +subsys_initcall(ux500_rtcrtt_init); |