avionic design with actual uboot and tooling

submodule of avionic design uboot bootloader and with included tools to
get you started , read readme.md and readme-tk1-loader.md

u-boot/drivers/timer/Kconfig

@@ -0,0 +1,49 @@
+menu "Timer Support"
+
+config TIMER
+	bool "Enable driver model for timer drivers"
+	depends on DM
+	help
+	  Enable driver model for timer access. It uses the same API as
+	  lib/time.c, but now implemented by the uclass. The first timer
+	  will be used. The timer is usually a 32 bits free-running up
+	  counter. There may be no real tick, and no timer interrupt.
+
+config TIMER_EARLY
+	bool "Allow timer to be used early in U-Boot"
+	depends on TIMER
+	help
+	  In some cases the timer must be accessible before driver model is
+	  active. Examples include when using CONFIG_TRACE to trace U-Boot's
+	  execution before driver model is set up. Enable this option to
+	  use an early timer. These functions must be supported by your timer
+	  driver: timer_early_get_count() and timer_early_get_rate().
+
+config ALTERA_TIMER
+	bool "Altera timer support"
+	depends on TIMER
+	help
+	  Select this to enable a timer for Altera devices. Please find
+	  details on the "Embedded Peripherals IP User Guide" of Altera.
+
+config SANDBOX_TIMER
+	bool "Sandbox timer support"
+	depends on SANDBOX && TIMER
+	help
+	  Select this to enable an emulated timer for sandbox. It gets
+	  time from host os.
+
+config X86_TSC_TIMER
+	bool "x86 Time-Stamp Counter (TSC) timer support"
+	depends on TIMER && X86
+	default y if X86
+	help
+	  Select this to enable Time-Stamp Counter (TSC) timer for x86.
+
+config OMAP_TIMER
+	bool "Omap timer support"
+	depends on TIMER
+	help
+	  Select this to enable an timer for Omap devices.
+
+endmenu

u-boot/drivers/timer/Makefile

@@ -0,0 +1,11 @@
+#
+# Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_TIMER)		+= timer-uclass.o
+obj-$(CONFIG_ALTERA_TIMER)	+= altera_timer.o
+obj-$(CONFIG_SANDBOX_TIMER)	+= sandbox_timer.o
+obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o
+obj-$(CONFIG_OMAP_TIMER)	+= omap-timer.o

u-boot/drivers/timer/altera_timer.c

@@ -0,0 +1,99 @@
+/*
+ * (C) Copyright 2000-2002
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
+ * Scott McNutt <smcnutt@psyent.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+#include <asm/io.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* control register */
+#define ALTERA_TIMER_CONT	BIT(1)	/* Continuous mode */
+#define ALTERA_TIMER_START	BIT(2)	/* Start timer */
+#define ALTERA_TIMER_STOP	BIT(3)	/* Stop timer */
+
+struct altera_timer_regs {
+	u32	status;		/* Timer status reg */
+	u32	control;	/* Timer control reg */
+	u32	periodl;	/* Timeout period low */
+	u32	periodh;	/* Timeout period high */
+	u32	snapl;		/* Snapshot low */
+	u32	snaph;		/* Snapshot high */
+};
+
+struct altera_timer_platdata {
+	struct altera_timer_regs *regs;
+};
+
+static int altera_timer_get_count(struct udevice *dev, u64 *count)
+{
+	struct altera_timer_platdata *plat = dev->platdata;
+	struct altera_timer_regs *const regs = plat->regs;
+	u32 val;
+
+	/* Trigger update */
+	writel(0x0, &regs->snapl);
+
+	/* Read timer value */
+	val = readl(&regs->snapl) & 0xffff;
+	val |= (readl(&regs->snaph) & 0xffff) << 16;
+	*count = timer_conv_64(~val);
+
+	return 0;
+}
+
+static int altera_timer_probe(struct udevice *dev)
+{
+	struct altera_timer_platdata *plat = dev->platdata;
+	struct altera_timer_regs *const regs = plat->regs;
+
+	writel(0, &regs->status);
+	writel(0, &regs->control);
+	writel(ALTERA_TIMER_STOP, &regs->control);
+
+	writel(0xffff, &regs->periodl);
+	writel(0xffff, &regs->periodh);
+	writel(ALTERA_TIMER_CONT | ALTERA_TIMER_START, &regs->control);
+
+	return 0;
+}
+
+static int altera_timer_ofdata_to_platdata(struct udevice *dev)
+{
+	struct altera_timer_platdata *plat = dev_get_platdata(dev);
+
+	plat->regs = map_physmem(dev_get_addr(dev),
+				 sizeof(struct altera_timer_regs),
+				 MAP_NOCACHE);
+
+	return 0;
+}
+
+static const struct timer_ops altera_timer_ops = {
+	.get_count = altera_timer_get_count,
+};
+
+static const struct udevice_id altera_timer_ids[] = {
+	{ .compatible = "altr,timer-1.0" },
+	{}
+};
+
+U_BOOT_DRIVER(altera_timer) = {
+	.name	= "altera_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = altera_timer_ids,
+	.ofdata_to_platdata = altera_timer_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct altera_timer_platdata),
+	.probe = altera_timer_probe,
+	.ops	= &altera_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};

u-boot/drivers/timer/omap-timer.c

@@ -0,0 +1,109 @@
+/*
+ * TI OMAP timer driver
+ *
+ * Copyright (C) 2015, Texas Instruments, Incorporated
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* Timer register bits */
+#define TCLR_START			BIT(0)	/* Start=1 */
+#define TCLR_AUTO_RELOAD		BIT(1)	/* Auto reload */
+#define TCLR_PRE_EN			BIT(5)	/* Pre-scaler enable */
+#define TCLR_PTV_SHIFT			(2)	/* Pre-scaler shift value */
+
+#define TIMER_CLOCK             (V_SCLK / (2 << CONFIG_SYS_PTV))
+
+struct omap_gptimer_regs {
+	unsigned int tidr;		/* offset 0x00 */
+	unsigned char res1[12];
+	unsigned int tiocp_cfg;		/* offset 0x10 */
+	unsigned char res2[12];
+	unsigned int tier;		/* offset 0x20 */
+	unsigned int tistatr;		/* offset 0x24 */
+	unsigned int tistat;		/* offset 0x28 */
+	unsigned int tisr;		/* offset 0x2c */
+	unsigned int tcicr;		/* offset 0x30 */
+	unsigned int twer;		/* offset 0x34 */
+	unsigned int tclr;		/* offset 0x38 */
+	unsigned int tcrr;		/* offset 0x3c */
+	unsigned int tldr;		/* offset 0x40 */
+	unsigned int ttgr;		/* offset 0x44 */
+	unsigned int twpc;		/* offset 0x48 */
+	unsigned int tmar;		/* offset 0x4c */
+	unsigned int tcar1;		/* offset 0x50 */
+	unsigned int tscir;		/* offset 0x54 */
+	unsigned int tcar2;		/* offset 0x58 */
+};
+
+/* Omap Timer Priv */
+struct omap_timer_priv {
+	struct omap_gptimer_regs *regs;
+};
+
+static int omap_timer_get_count(struct udevice *dev, u64 *count)
+{
+	struct omap_timer_priv *priv = dev_get_priv(dev);
+
+	*count = readl(&priv->regs->tcrr);
+
+	return 0;
+}
+
+static int omap_timer_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct omap_timer_priv *priv = dev_get_priv(dev);
+
+	uc_priv->clock_rate = TIMER_CLOCK;
+
+	/* start the counter ticking up, reload value on overflow */
+	writel(0, &priv->regs->tldr);
+	/* enable timer */
+	writel((CONFIG_SYS_PTV << 2) | TCLR_PRE_EN | TCLR_AUTO_RELOAD |
+	       TCLR_START, &priv->regs->tclr);
+
+	return 0;
+}
+
+static int omap_timer_ofdata_to_platdata(struct udevice *dev)
+{
+	struct omap_timer_priv *priv = dev_get_priv(dev);
+
+	priv->regs = map_physmem(dev_get_addr(dev),
+				 sizeof(struct omap_gptimer_regs), MAP_NOCACHE);
+
+	return 0;
+}
+
+
+static const struct timer_ops omap_timer_ops = {
+	.get_count = omap_timer_get_count,
+};
+
+static const struct udevice_id omap_timer_ids[] = {
+	{ .compatible = "ti,am335x-timer" },
+	{ .compatible = "ti,am4372-timer" },
+	{ .compatible = "ti,omap5430-timer" },
+	{}
+};
+
+U_BOOT_DRIVER(omap_timer) = {
+	.name	= "omap_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = omap_timer_ids,
+	.ofdata_to_platdata = omap_timer_ofdata_to_platdata,
+	.priv_auto_alloc_size = sizeof(struct omap_timer_priv),
+	.probe = omap_timer_probe,
+	.ops	= &omap_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};

u-boot/drivers/timer/sandbox_timer.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+#include <os.h>
+
+#define SANDBOX_TIMER_RATE	1000000
+
+/* system timer offset in ms */
+static unsigned long sandbox_timer_offset;
+
+void sandbox_timer_add_offset(unsigned long offset)
+{
+	sandbox_timer_offset += offset;
+}
+
+u64 notrace timer_early_get_count(void)
+{
+	return os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
+}
+
+unsigned long notrace timer_early_get_rate(void)
+{
+	return SANDBOX_TIMER_RATE;
+}
+
+static notrace int sandbox_timer_get_count(struct udevice *dev, u64 *count)
+{
+	*count = timer_early_get_count();
+
+	return 0;
+}
+
+static int sandbox_timer_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (!uc_priv->clock_rate)
+		uc_priv->clock_rate = SANDBOX_TIMER_RATE;
+
+	return 0;
+}
+
+static const struct timer_ops sandbox_timer_ops = {
+	.get_count = sandbox_timer_get_count,
+};
+
+static const struct udevice_id sandbox_timer_ids[] = {
+	{ .compatible = "sandbox,timer" },
+	{ }
+};
+
+U_BOOT_DRIVER(sandbox_timer) = {
+	.name	= "sandbox_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = sandbox_timer_ids,
+	.probe = sandbox_timer_probe,
+	.ops	= &sandbox_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};
+
+/* This is here in case we don't have a device tree */
+U_BOOT_DEVICE(sandbox_timer_non_fdt) = {
+	.name = "sandbox_timer",
+};

u-boot/drivers/timer/timer-uclass.c

@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/lists.h>
+#include <dm/device-internal.h>
+#include <errno.h>
+#include <timer.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * Implement a timer uclass to work with lib/time.c. The timer is usually
+ * a 32/64 bits free-running up counter. The get_rate() method is used to get
+ * the input clock frequency of the timer. The get_count() method is used
+ * to get the current 64 bits count value. If the hardware is counting down,
+ * the value should be inversed inside the method. There may be no real
+ * tick, and no timer interrupt.
+ */
+
+int notrace timer_get_count(struct udevice *dev, u64 *count)
+{
+	const struct timer_ops *ops = device_get_ops(dev);
+
+	if (!ops->get_count)
+		return -ENOSYS;
+
+	return ops->get_count(dev, count);
+}
+
+unsigned long notrace timer_get_rate(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev->uclass_priv;
+
+	return uc_priv->clock_rate;
+}
+
+static int timer_pre_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	uc_priv->clock_rate = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
+					     "clock-frequency", 0);
+
+	return 0;
+}
+
+static int timer_post_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (!uc_priv->clock_rate)
+		return -EINVAL;
+
+	return 0;
+}
+
+u64 timer_conv_64(u32 count)
+{
+	/* increment tbh if tbl has rolled over */
+	if (count < gd->timebase_l)
+		gd->timebase_h++;
+	gd->timebase_l = count;
+	return ((u64)gd->timebase_h << 32) | gd->timebase_l;
+}
+
+int notrace dm_timer_init(void)
+{
+	const void *blob = gd->fdt_blob;
+	struct udevice *dev = NULL;
+	int node;
+	int ret;
+
+	if (gd->timer)
+		return 0;
+
+	/* Check for a chosen timer to be used for tick */
+	node = fdtdec_get_chosen_node(blob, "tick-timer");
+	if (node < 0) {
+		/* No chosen timer, trying first available timer */
+		ret = uclass_first_device_err(UCLASS_TIMER, &dev);
+		if (ret)
+			return ret;
+	} else {
+		if (uclass_get_device_by_of_offset(UCLASS_TIMER, node, &dev)) {
+			/*
+			 * If the timer is not marked to be bound before
+			 * relocation, bind it anyway.
+			 */
+			if (node > 0 &&
+			    !lists_bind_fdt(gd->dm_root, blob, node, &dev)) {
+				ret = device_probe(dev);
+				if (ret)
+					return ret;
+			}
+		}
+	}
+
+	if (dev) {
+		gd->timer = dev;
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
+UCLASS_DRIVER(timer) = {
+	.id		= UCLASS_TIMER,
+	.name		= "timer",
+	.pre_probe	= timer_pre_probe,
+	.flags		= DM_UC_FLAG_SEQ_ALIAS,
+	.post_probe	= timer_post_probe,
+	.per_device_auto_alloc_size = sizeof(struct timer_dev_priv),
+};

u-boot/drivers/timer/tsc_timer.c

@@ -0,0 +1,379 @@
+/*
+ * Copyright (c) 2012 The Chromium OS Authors.
+ *
+ * TSC calibration codes are adapted from Linux kernel
+ * arch/x86/kernel/tsc_msr.c and arch/x86/kernel/tsc.c
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <malloc.h>
+#include <timer.h>
+#include <asm/io.h>
+#include <asm/i8254.h>
+#include <asm/ibmpc.h>
+#include <asm/msr.h>
+#include <asm/u-boot-x86.h>
+
+/* CPU reference clock frequency: in KHz */
+#define FREQ_83		83200
+#define FREQ_100	99840
+#define FREQ_133	133200
+#define FREQ_166	166400
+
+#define MAX_NUM_FREQS	8
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * According to Intel 64 and IA-32 System Programming Guide,
+ * if MSR_PERF_STAT[31] is set, the maximum resolved bus ratio can be
+ * read in MSR_PLATFORM_ID[12:8], otherwise in MSR_PERF_STAT[44:40].
+ * Unfortunately some Intel Atom SoCs aren't quite compliant to this,
+ * so we need manually differentiate SoC families. This is what the
+ * field msr_plat does.
+ */
+struct freq_desc {
+	u8 x86_family;	/* CPU family */
+	u8 x86_model;	/* model */
+	/* 2: use 100MHz, 1: use MSR_PLATFORM_INFO, 0: MSR_IA32_PERF_STATUS */
+	u8 msr_plat;
+	u32 freqs[MAX_NUM_FREQS];
+};
+
+static struct freq_desc freq_desc_tables[] = {
+	/* PNW */
+	{ 6, 0x27, 0, { 0, 0, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
+	/* CLV+ */
+	{ 6, 0x35, 0, { 0, FREQ_133, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
+	/* TNG */
+	{ 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } },
+	/* VLV2 */
+	{ 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
+	/* Ivybridge */
+	{ 6, 0x3a, 2, { 0, 0, 0, 0, 0, 0, 0, 0 } },
+	/* ANN */
+	{ 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } },
+};
+
+static int match_cpu(u8 family, u8 model)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(freq_desc_tables); i++) {
+		if ((family == freq_desc_tables[i].x86_family) &&
+		    (model == freq_desc_tables[i].x86_model))
+			return i;
+	}
+
+	return -1;
+}
+
+/* Map CPU reference clock freq ID(0-7) to CPU reference clock freq(KHz) */
+#define id_to_freq(cpu_index, freq_id) \
+	(freq_desc_tables[cpu_index].freqs[freq_id])
+
+/*
+ * Do MSR calibration only for known/supported CPUs.
+ *
+ * Returns the calibration value or 0 if MSR calibration failed.
+ */
+static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
+{
+	u32 lo, hi, ratio, freq_id, freq;
+	unsigned long res;
+	int cpu_index;
+
+	cpu_index = match_cpu(gd->arch.x86, gd->arch.x86_model);
+	if (cpu_index < 0)
+		return 0;
+
+	if (freq_desc_tables[cpu_index].msr_plat) {
+		rdmsr(MSR_PLATFORM_INFO, lo, hi);
+		ratio = (lo >> 8) & 0x1f;
+	} else {
+		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+		ratio = (hi >> 8) & 0x1f;
+	}
+	debug("Maximum core-clock to bus-clock ratio: 0x%x\n", ratio);
+
+	if (!ratio)
+		goto fail;
+
+	if (freq_desc_tables[cpu_index].msr_plat == 2) {
+		/* TODO: Figure out how best to deal with this */
+		freq = FREQ_100;
+		debug("Using frequency: %u KHz\n", freq);
+	} else {
+		/* Get FSB FREQ ID */
+		rdmsr(MSR_FSB_FREQ, lo, hi);
+		freq_id = lo & 0x7;
+		freq = id_to_freq(cpu_index, freq_id);
+		debug("Resolved frequency ID: %u, frequency: %u KHz\n",
+		      freq_id, freq);
+	}
+	if (!freq)
+		goto fail;
+
+	/* TSC frequency = maximum resolved freq * maximum resolved bus ratio */
+	res = freq * ratio / 1000;
+	debug("TSC runs at %lu MHz\n", res);
+
+	return res;
+
+fail:
+	debug("Fast TSC calibration using MSR failed\n");
+	return 0;
+}
+
+/*
+ * This reads the current MSB of the PIT counter, and
+ * checks if we are running on sufficiently fast and
+ * non-virtualized hardware.
+ *
+ * Our expectations are:
+ *
+ *  - the PIT is running at roughly 1.19MHz
+ *
+ *  - each IO is going to take about 1us on real hardware,
+ *    but we allow it to be much faster (by a factor of 10) or
+ *    _slightly_ slower (ie we allow up to a 2us read+counter
+ *    update - anything else implies a unacceptably slow CPU
+ *    or PIT for the fast calibration to work.
+ *
+ *  - with 256 PIT ticks to read the value, we have 214us to
+ *    see the same MSB (and overhead like doing a single TSC
+ *    read per MSB value etc).
+ *
+ *  - We're doing 2 reads per loop (LSB, MSB), and we expect
+ *    them each to take about a microsecond on real hardware.
+ *    So we expect a count value of around 100. But we'll be
+ *    generous, and accept anything over 50.
+ *
+ *  - if the PIT is stuck, and we see *many* more reads, we
+ *    return early (and the next caller of pit_expect_msb()
+ *    then consider it a failure when they don't see the
+ *    next expected value).
+ *
+ * These expectations mean that we know that we have seen the
+ * transition from one expected value to another with a fairly
+ * high accuracy, and we didn't miss any events. We can thus
+ * use the TSC value at the transitions to calculate a pretty
+ * good value for the TSC frequencty.
+ */
+static inline int pit_verify_msb(unsigned char val)
+{
+	/* Ignore LSB */
+	inb(0x42);
+	return inb(0x42) == val;
+}
+
+static inline int pit_expect_msb(unsigned char val, u64 *tscp,
+				 unsigned long *deltap)
+{
+	int count;
+	u64 tsc = 0, prev_tsc = 0;
+
+	for (count = 0; count < 50000; count++) {
+		if (!pit_verify_msb(val))
+			break;
+		prev_tsc = tsc;
+		tsc = rdtsc();
+	}
+	*deltap = rdtsc() - prev_tsc;
+	*tscp = tsc;
+
+	/*
+	 * We require _some_ success, but the quality control
+	 * will be based on the error terms on the TSC values.
+	 */
+	return count > 5;
+}
+
+/*
+ * How many MSB values do we want to see? We aim for
+ * a maximum error rate of 500ppm (in practice the
+ * real error is much smaller), but refuse to spend
+ * more than 50ms on it.
+ */
+#define MAX_QUICK_PIT_MS 50
+#define MAX_QUICK_PIT_ITERATIONS (MAX_QUICK_PIT_MS * PIT_TICK_RATE / 1000 / 256)
+
+static unsigned long __maybe_unused quick_pit_calibrate(void)
+{
+	int i;
+	u64 tsc, delta;
+	unsigned long d1, d2;
+
+	/* Set the Gate high, disable speaker */
+	outb((inb(0x61) & ~0x02) | 0x01, 0x61);
+
+	/*
+	 * Counter 2, mode 0 (one-shot), binary count
+	 *
+	 * NOTE! Mode 2 decrements by two (and then the
+	 * output is flipped each time, giving the same
+	 * final output frequency as a decrement-by-one),
+	 * so mode 0 is much better when looking at the
+	 * individual counts.
+	 */
+	outb(0xb0, 0x43);
+
+	/* Start at 0xffff */
+	outb(0xff, 0x42);
+	outb(0xff, 0x42);
+
+	/*
+	 * The PIT starts counting at the next edge, so we
+	 * need to delay for a microsecond. The easiest way
+	 * to do that is to just read back the 16-bit counter
+	 * once from the PIT.
+	 */
+	pit_verify_msb(0);
+
+	if (pit_expect_msb(0xff, &tsc, &d1)) {
+		for (i = 1; i <= MAX_QUICK_PIT_ITERATIONS; i++) {
+			if (!pit_expect_msb(0xff-i, &delta, &d2))
+				break;
+
+			/*
+			 * Iterate until the error is less than 500 ppm
+			 */
+			delta -= tsc;
+			if (d1+d2 >= delta >> 11)
+				continue;
+
+			/*
+			 * Check the PIT one more time to verify that
+			 * all TSC reads were stable wrt the PIT.
+			 *
+			 * This also guarantees serialization of the
+			 * last cycle read ('d2') in pit_expect_msb.
+			 */
+			if (!pit_verify_msb(0xfe - i))
+				break;
+			goto success;
+		}
+	}
+	debug("Fast TSC calibration failed\n");
+	return 0;
+
+success:
+	/*
+	 * Ok, if we get here, then we've seen the
+	 * MSB of the PIT decrement 'i' times, and the
+	 * error has shrunk to less than 500 ppm.
+	 *
+	 * As a result, we can depend on there not being
+	 * any odd delays anywhere, and the TSC reads are
+	 * reliable (within the error).
+	 *
+	 * kHz = ticks / time-in-seconds / 1000;
+	 * kHz = (t2 - t1) / (I * 256 / PIT_TICK_RATE) / 1000
+	 * kHz = ((t2 - t1) * PIT_TICK_RATE) / (I * 256 * 1000)
+	 */
+	delta *= PIT_TICK_RATE;
+	delta /= (i*256*1000);
+	debug("Fast TSC calibration using PIT\n");
+	return delta / 1000;
+}
+
+/* Get the speed of the TSC timer in MHz */
+unsigned notrace long get_tbclk_mhz(void)
+{
+	return get_tbclk() / 1000000;
+}
+
+static ulong get_ms_timer(void)
+{
+	return (get_ticks() * 1000) / get_tbclk();
+}
+
+ulong get_timer(ulong base)
+{
+	return get_ms_timer() - base;
+}
+
+ulong notrace timer_get_us(void)
+{
+	return get_ticks() / get_tbclk_mhz();
+}
+
+ulong timer_get_boot_us(void)
+{
+	return timer_get_us();
+}
+
+void __udelay(unsigned long usec)
+{
+	u64 now = get_ticks();
+	u64 stop;
+
+	stop = now + usec * get_tbclk_mhz();
+
+	while ((int64_t)(stop - get_ticks()) > 0)
+#if defined(CONFIG_QEMU) && defined(CONFIG_SMP)
+		/*
+		 * Add a 'pause' instruction on qemu target,
+		 * to give other VCPUs a chance to run.
+		 */
+		asm volatile("pause");
+#else
+		;
+#endif
+}
+
+static int tsc_timer_get_count(struct udevice *dev, u64 *count)
+{
+	u64 now_tick = rdtsc();
+
+	*count = now_tick - gd->arch.tsc_base;
+
+	return 0;
+}
+
+static int tsc_timer_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	gd->arch.tsc_base = rdtsc();
+
+	/*
+	 * If there is no clock frequency specified in the device tree,
+	 * calibrate it by ourselves.
+	 */
+	if (!uc_priv->clock_rate) {
+		unsigned long fast_calibrate;
+
+		fast_calibrate = try_msr_calibrate_tsc();
+		if (!fast_calibrate) {
+			fast_calibrate = quick_pit_calibrate();
+			if (!fast_calibrate)
+				panic("TSC frequency is ZERO");
+		}
+
+		uc_priv->clock_rate = fast_calibrate * 1000000;
+	}
+
+	return 0;
+}
+
+static const struct timer_ops tsc_timer_ops = {
+	.get_count = tsc_timer_get_count,
+};
+
+static const struct udevice_id tsc_timer_ids[] = {
+	{ .compatible = "x86,tsc-timer", },
+	{ }
+};
+
+U_BOOT_DRIVER(tsc_timer) = {
+	.name	= "tsc_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = tsc_timer_ids,
+	.probe = tsc_timer_probe,
+	.ops	= &tsc_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};