131 lines
3.0 KiB
C
131 lines
3.0 KiB
C
/*
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* Copyright (C) 2014 Antony Pavlov <antonynpavlov@gmail.com>
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*
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* Based on
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* https://github.com/RC-MODULE/linux-3.10.x/tree/k1879-3.10.28/arch/arm/mach-uemd/clocksource.c
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* (C) 2011 RC Module, Sergey Mironov <ierton@gmail.com>
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*
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* This file is part of barebox.
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* See file CREDITS for list of people who contributed to this project.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <common.h>
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#include <io.h>
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#include <init.h>
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#include <linux/bitops.h>
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#include <linux/clk.h>
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#include <clock.h>
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#define TIMER_LOAD 0x00
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#define TIMER_VALUE 0x04
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#define TIMER_CONTROL 0x08
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#define TIMER_CTRL_ENABLE BIT(7)
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/*
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* TIMER_CONTROL_PERIODIC:
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* The counter generates an interrupt at a constant interval,
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* reloading the original value after wrapping past zero.
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*/
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#define TIMER_CTRL_PERIODIC BIT(6)
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/* interrupt enable */
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#define TIMER_CTRL_IE BIT(5)
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/* Prescalers */
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#define TIMER_CTRL_P1 (0 << 2)
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#define TIMER_CTRL_P16 (1 << 2)
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#define TIMER_CTRL_P256 (2 << 2)
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/* Counter register size is 32 Bit long */
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#define TIMER_CTRL_32BIT BIT(1)
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static void __iomem *timer_base;
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static uint64_t uemd_timer_cs_read(void)
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{
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/* Down counter! */
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return ~__raw_readl(timer_base + TIMER_VALUE);
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}
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static struct clocksource uemd_cs = {
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.read = uemd_timer_cs_read,
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.mask = CLOCKSOURCE_MASK(32),
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};
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static int uemd_timer_probe(struct device_d *dev)
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{
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int mode;
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struct clk *timer_clk;
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/* use only one timer */
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if (timer_base)
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return -EBUSY;
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timer_base = dev_request_mem_region(dev, 0);
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if (!timer_base) {
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dev_err(dev, "could not get memory region\n");
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return -ENODEV;
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}
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timer_clk = clk_get(dev, NULL);
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if (IS_ERR(timer_clk)) {
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int ret = PTR_ERR(timer_clk);
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dev_err(dev, "clock not found: %d\n", ret);
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return ret;
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}
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/* Stop timer */
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__raw_writel(0, timer_base + TIMER_CONTROL);
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/* Setup */
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__raw_writel(0xffffffff, timer_base + TIMER_LOAD);
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__raw_writel(0xffffffff, timer_base + TIMER_VALUE);
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mode = TIMER_CTRL_32BIT |
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TIMER_CTRL_PERIODIC |
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TIMER_CTRL_P1;
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__raw_writel(mode, timer_base + TIMER_CONTROL);
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/* Fire it up! */
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mode |= TIMER_CTRL_ENABLE;
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__raw_writel(mode, timer_base + TIMER_CONTROL);
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clocks_calc_mult_shift(&uemd_cs.mult, &uemd_cs.shift,
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clk_get_rate(timer_clk), NSEC_PER_SEC, 10);
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init_clock(&uemd_cs);
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return 0;
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}
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static __maybe_unused struct of_device_id uemd_timer_dt_ids[] = {
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{
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.compatible = "module,uemd-timer",
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}, {
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/* sentinel */
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}
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};
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static struct driver_d uemd_timer_driver = {
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.probe = uemd_timer_probe,
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.name = "uemd-timer",
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.of_compatible = DRV_OF_COMPAT(uemd_timer_dt_ids),
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};
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static int uemd_timer_init(void)
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{
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return platform_driver_register(&uemd_timer_driver);
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}
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coredevice_initcall(uemd_timer_init);
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