111 lines
2.3 KiB
C
111 lines
2.3 KiB
C
/*
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* Copyright (C) 2012 Jean-Christophe PLAGNIOL-VILLARD <plagnio@jcrosoft.com>
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*
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* Under GPL v2
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*/
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#include <common.h>
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#include <init.h>
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#include <clock.h>
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#include <io.h>
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#include <driver.h>
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#include <errno.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#define TWD_TIMER_LOAD 0x00
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#define TWD_TIMER_COUNTER 0x04
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#define TWD_TIMER_CONTROL 0x08
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#define TWD_TIMER_INTSTAT 0x0C
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#define TWD_TIMER_CONTROL_ENABLE (1 << 0)
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#define TWD_TIMER_CONTROL_ONESHOT (0 << 1)
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#define TWD_TIMER_CONTROL_PERIODIC (1 << 1)
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#define TWD_TIMER_CONTROL_IT_ENABLE (1 << 2)
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#define TWD_TIMER_CONTROL_PRESC(x) (((x) & 0xff) << 8)
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static __iomem void *twd_base;
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static struct clk *twd_clk;
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static uint64_t smp_twd_read(void)
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{
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return ~readl(twd_base + TWD_TIMER_COUNTER);
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}
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static struct clocksource smp_twd_clksrc = {
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.read = smp_twd_read,
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.shift = 20,
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.mask = CLOCKSOURCE_MASK(32),
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};
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#define SMP_TWD_MAX_FREQ (25 *1000 * 1000)
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static int smp_twd_probe(struct device_d *dev)
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{
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u32 tick_rate;
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u32 val;
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int ret;
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u32 presc = 0;
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twd_clk = clk_get(dev, NULL);
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if (IS_ERR(twd_clk)) {
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ret = PTR_ERR(twd_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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ret = clk_enable(twd_clk);
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if (ret < 0) {
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dev_err(dev, "clock failed to enable: %d\n", ret);
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clk_put(twd_clk);
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return ret;
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}
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twd_base = dev_request_mem_region(dev, 0);
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tick_rate = clk_get_rate(twd_clk);
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if (tick_rate > SMP_TWD_MAX_FREQ) {
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presc = tick_rate / SMP_TWD_MAX_FREQ;
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if (presc)
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presc--;
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presc = min((u32)0xff, presc);
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tick_rate /= presc + 1;
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}
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val = TWD_TIMER_CONTROL_PRESC(presc) |
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TWD_TIMER_CONTROL_PERIODIC;
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writel(val, twd_base + TWD_TIMER_CONTROL);
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writel(0xffffffff, twd_base + TWD_TIMER_LOAD);
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val = readl(twd_base + TWD_TIMER_CONTROL);
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val |= TWD_TIMER_CONTROL_ENABLE;
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writel(val, twd_base + TWD_TIMER_CONTROL);
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smp_twd_clksrc.mult = clocksource_hz2mult(tick_rate, smp_twd_clksrc.shift);
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init_clock(&smp_twd_clksrc);
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return 0;
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}
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static __maybe_unused struct of_device_id smp_twd_compatible[] = {
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{
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.compatible = "arm,cortex-a9-twd-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 smp_twd_driver = {
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.name = "smp_twd",
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.probe = smp_twd_probe,
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.of_compatible = DRV_OF_COMPAT(smp_twd_compatible),
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};
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static int smp_twd_init(void)
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{
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return platform_driver_register(&smp_twd_driver);
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}
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coredevice_initcall(smp_twd_init);
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