projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 5732b38d SS |
2 | /* |
| 3 | * dma_timer.c -- Freescale ColdFire DMA Timer. | |
| 4 | * | |
| 5 | * Copyright (C) 2007, Benedikt Spranger <[email protected]> | |
| 6 | * Copyright (C) 2008. Sebastian Siewior, Linutronix | |
| 7 | * | |
| 8 | */ | |
| 9 | ||
| 10 | #include <linux/clocksource.h> | |
| 11 | #include <linux/io.h> | |
| 12 | ||
| 13 | #include <asm/machdep.h> | |
| 14 | #include <asm/coldfire.h> | |
| 15 | #include <asm/mcfpit.h> | |
| 16 | #include <asm/mcfsim.h> | |
| 17 | ||
| 18 | #define DMA_TIMER_0 (0x00) | |
| 19 | #define DMA_TIMER_1 (0x40) | |
| 20 | #define DMA_TIMER_2 (0x80) | |
| 21 | #define DMA_TIMER_3 (0xc0) | |
| 22 | ||
| 23 | #define DTMR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x400) | |
| 24 | #define DTXMR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x402) | |
| 25 | #define DTER0 (MCF_IPSBAR + DMA_TIMER_0 + 0x403) | |
| 26 | #define DTRR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x404) | |
| 27 | #define DTCR0 (MCF_IPSBAR + DMA_TIMER_0 + 0x408) | |
| 28 | #define DTCN0 (MCF_IPSBAR + DMA_TIMER_0 + 0x40c) | |
| 29 | ||
| 30 | #define DMA_FREQ ((MCF_CLK / 2) / 16) | |
| 31 | ||
| 32 | /* DTMR */ | |
| 33 | #define DMA_DTMR_RESTART (1 << 3) | |
| 34 | #define DMA_DTMR_CLK_DIV_1 (1 << 1) | |
| 35 | #define DMA_DTMR_CLK_DIV_16 (2 << 1) | |
| 36 | #define DMA_DTMR_ENABLE (1 << 0) | |
| 37 | ||
| a5a1d1c2 | 38 | static u64 cf_dt_get_cycles(struct clocksource *cs) |
| 5732b38d SS |
39 | { |
| 40 | return __raw_readl(DTCN0); | |
| 41 | } | |
| 42 | ||
| 43 | static struct clocksource clocksource_cf_dt = { | |
| 44 | .name = "coldfire_dma_timer", | |
| 45 | .rating = 200, | |
| 46 | .read = cf_dt_get_cycles, | |
| 47 | .mask = CLOCKSOURCE_MASK(32), | |
| 5732b38d SS |
48 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| 49 | }; | |
| 50 | ||
| 51 | static int __init init_cf_dt_clocksource(void) | |
| 52 | { | |
| 53 | /* | |
| 54 | * We setup DMA timer 0 in free run mode. This incrementing counter is | |
| 55 | * used as a highly precious clock source. With MCF_CLOCK = 150 MHz we | |
| 56 | * get a ~213 ns resolution and the 32bit register will overflow almost | |
| 57 | * every 15 minutes. | |
| 58 | */ | |
| 59 | __raw_writeb(0x00, DTXMR0); | |
| 60 | __raw_writeb(0x00, DTER0); | |
| 61 | __raw_writel(0x00000000, DTRR0); | |
| 62 | __raw_writew(DMA_DTMR_CLK_DIV_16 | DMA_DTMR_ENABLE, DTMR0); | |
| 010f3f16 | 63 | return clocksource_register_hz(&clocksource_cf_dt, DMA_FREQ); |
| 5732b38d SS |
64 | } |
| 65 | ||
| 66 | arch_initcall(init_cf_dt_clocksource); | |
| 5bed10a5 SS |
67 | |
| 68 | #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ | |
| 69 | #define CYC2NS_SCALE ((1000000 << CYC2NS_SCALE_FACTOR) / (DMA_FREQ / 1000)) | |
| 70 | ||
| 71 | static unsigned long long cycles2ns(unsigned long cycl) | |
| 72 | { | |
| 73 | return (unsigned long long) ((unsigned long long)cycl * | |
| 74 | CYC2NS_SCALE) >> CYC2NS_SCALE_FACTOR; | |
| 75 | } | |
| 76 | ||
| 77 | unsigned long long sched_clock(void) | |
| 78 | { | |
| 79 | unsigned long cycl = __raw_readl(DTCN0); | |
| 80 | ||
| 81 | return cycles2ns(cycl); | |
| 82 | } |