| 1 | /* |
| 2 | * Moschip MCS814x timer routines |
| 3 | * |
| 4 | * Copyright (C) 2012, Florian Fainelli <florian@openwrt.org> |
| 5 | * |
| 6 | * Licensed under GPLv2 |
| 7 | */ |
| 8 | #include <linux/kernel.h> |
| 9 | #include <linux/interrupt.h> |
| 10 | #include <linux/time.h> |
| 11 | #include <linux/timex.h> |
| 12 | #include <linux/irq.h> |
| 13 | #include <linux/err.h> |
| 14 | #include <linux/clk.h> |
| 15 | #include <linux/io.h> |
| 16 | #include <linux/of.h> |
| 17 | #include <linux/of_address.h> |
| 18 | |
| 19 | #include <asm/mach/time.h> |
| 20 | #include <mach/mcs814x.h> |
| 21 | |
| 22 | /* Timer block registers */ |
| 23 | #define TIMER_VAL 0x00 |
| 24 | #define TIMER_CTL 0x04 |
| 25 | #define TIMER_CTL_EN 0x01 |
| 26 | #define TIMER_CTL_DBG 0x02 |
| 27 | |
| 28 | static u32 last_reload; |
| 29 | static u32 timer_correct; |
| 30 | static u32 clock_rate; |
| 31 | static u32 timer_reload_value; |
| 32 | static void __iomem *mcs814x_timer_base; |
| 33 | |
| 34 | static inline unsigned long ticks2usecs(u32 x) |
| 35 | { |
| 36 | return x / (clock_rate / 1000000); |
| 37 | } |
| 38 | |
| 39 | /* |
| 40 | * Returns number of ms since last clock interrupt. Note that interrupts |
| 41 | * will have been disabled by do_gettimeoffset() |
| 42 | */ |
| 43 | static unsigned long mcs814x_gettimeoffset(void) |
| 44 | { |
| 45 | u32 ticks = readl_relaxed(mcs814x_timer_base + TIMER_VAL); |
| 46 | |
| 47 | if (ticks < last_reload) |
| 48 | return ticks2usecs(ticks + (u32)(0xffffffff - last_reload)); |
| 49 | else |
| 50 | return ticks2usecs(ticks - last_reload); |
| 51 | } |
| 52 | |
| 53 | |
| 54 | static irqreturn_t mcs814x_timer_interrupt(int irq, void *dev_id) |
| 55 | { |
| 56 | u32 count = readl_relaxed(mcs814x_timer_base + TIMER_VAL); |
| 57 | |
| 58 | /* take into account delay up to this moment */ |
| 59 | last_reload = count + timer_correct + timer_reload_value; |
| 60 | |
| 61 | if (last_reload < timer_reload_value) { |
| 62 | last_reload = timer_reload_value; |
| 63 | } else { |
| 64 | if (timer_correct == 0) |
| 65 | timer_correct = readl_relaxed(mcs814x_timer_base + TIMER_VAL) - count; |
| 66 | } |
| 67 | writel_relaxed(last_reload, mcs814x_timer_base + TIMER_VAL); |
| 68 | |
| 69 | timer_tick(); |
| 70 | |
| 71 | return IRQ_HANDLED; |
| 72 | } |
| 73 | |
| 74 | static struct irqaction mcs814x_timer_irq = { |
| 75 | .name = "mcs814x-timer", |
| 76 | .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, |
| 77 | .handler = mcs814x_timer_interrupt, |
| 78 | }; |
| 79 | |
| 80 | static struct of_device_id mcs814x_timer_ids[] = { |
| 81 | { .compatible = "moschip,mcs814x-timer" }, |
| 82 | { /* sentinel */ }, |
| 83 | }; |
| 84 | |
| 85 | static void __init mcs814x_of_timer_init(void) |
| 86 | { |
| 87 | struct device_node *np; |
| 88 | const unsigned int *intspec; |
| 89 | |
| 90 | np = of_find_matching_node(NULL, mcs814x_timer_ids); |
| 91 | if (!np) |
| 92 | panic("unable to find compatible timer node in dtb"); |
| 93 | |
| 94 | mcs814x_timer_base = of_iomap(np, 0); |
| 95 | if (!mcs814x_timer_base) |
| 96 | panic("unable to remap timer cpu registers"); |
| 97 | |
| 98 | intspec = of_get_property(np, "interrupts", NULL); |
| 99 | if (!intspec) |
| 100 | panic("no interrupts property for timer"); |
| 101 | |
| 102 | mcs814x_timer_irq.irq = be32_to_cpup(intspec); |
| 103 | } |
| 104 | |
| 105 | static void __init mcs814x_timer_init(void) |
| 106 | { |
| 107 | struct clk *clk; |
| 108 | |
| 109 | clk = clk_get_sys("timer0", NULL); |
| 110 | if (IS_ERR_OR_NULL(clk)) |
| 111 | panic("unable to get timer0 clock"); |
| 112 | |
| 113 | clock_rate = clk_get_rate(clk); |
| 114 | |
| 115 | mcs814x_of_timer_init(); |
| 116 | |
| 117 | pr_info("Timer frequency: %d (kHz)\n", clock_rate / 1000); |
| 118 | |
| 119 | timer_reload_value = 0xffffffff - (clock_rate / HZ); |
| 120 | |
| 121 | /* disable timer */ |
| 122 | writel_relaxed(~TIMER_CTL_EN, mcs814x_timer_base + TIMER_CTL); |
| 123 | writel_relaxed(timer_reload_value, mcs814x_timer_base + TIMER_VAL); |
| 124 | last_reload = timer_reload_value; |
| 125 | |
| 126 | setup_irq(mcs814x_timer_irq.irq, &mcs814x_timer_irq); |
| 127 | /* enable timer, stop timer in debug mode */ |
| 128 | writel_relaxed(TIMER_CTL_EN | TIMER_CTL_DBG, |
| 129 | mcs814x_timer_base + TIMER_CTL); |
| 130 | } |
| 131 | |
| 132 | struct sys_timer mcs814x_timer = { |
| 133 | .init = mcs814x_timer_init, |
| 134 | .offset = mcs814x_gettimeoffset, |
| 135 | }; |
| 136 | |
