ee327d1d93
This driver supports the watchdog timer found on Apple's M1 SoC. On systems that use these SoC, the watchdog timer is the primary way to reboot the system. Signed-off-by: Mark Kettenis <kettenis@openbsd.org> Reviewed-by: Sven Peter <sven@svenpeter.dev> Reviewed-by: Simon Glass <sjg@chromium.org> Reviewed-by: Stefan Roese <sr@denx.de> Tested-on: Apple M1 Macbook Tested-by: Simon Glass <sjg@chromium.org>
116 lines
2.2 KiB
C
116 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
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*/
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#include <clk.h>
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#include <dm.h>
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#include <wdt.h>
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#include <asm/io.h>
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#include <linux/delay.h>
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#define APPLE_WDT_CUR_TIME 0x10
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#define APPLE_WDT_BARK_TIME 0x14
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#define APPLE_WDT_CTRL 0x1c
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#define APPLE_WDT_CTRL_RESET_EN BIT(2)
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struct apple_wdt_priv {
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void *base;
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ulong clk_rate;
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};
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static int apple_wdt_reset(struct udevice *dev)
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{
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struct apple_wdt_priv *priv = dev_get_priv(dev);
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writel(0, priv->base + APPLE_WDT_CUR_TIME);
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return 0;
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}
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static int apple_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
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{
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struct apple_wdt_priv *priv = dev_get_priv(dev);
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u64 timeout;
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timeout = (timeout_ms * priv->clk_rate) / 1000;
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if (timeout > U32_MAX)
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return -EINVAL;
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writel(0, priv->base + APPLE_WDT_CUR_TIME);
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writel(timeout, priv->base + APPLE_WDT_BARK_TIME);
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writel(APPLE_WDT_CTRL_RESET_EN, priv->base + APPLE_WDT_CTRL);
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return 0;
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}
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static int apple_wdt_stop(struct udevice *dev)
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{
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struct apple_wdt_priv *priv = dev_get_priv(dev);
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writel(0, priv->base + APPLE_WDT_CTRL);
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return 0;
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}
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static int apple_wdt_expire_now(struct udevice *dev, ulong flags)
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{
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int ret;
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ret = apple_wdt_start(dev, 0, flags);
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if (ret)
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return ret;
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/*
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* It can take up to 25ms until the SoC actually resets, so
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* wait 50ms just to be sure.
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*/
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mdelay(50);
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return 0;
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}
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static const struct wdt_ops apple_wdt_ops = {
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.reset = apple_wdt_reset,
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.start = apple_wdt_start,
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.stop = apple_wdt_stop,
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.expire_now = apple_wdt_expire_now,
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};
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static const struct udevice_id apple_wdt_ids[] = {
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{ .compatible = "apple,wdt" },
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{ /* sentinel */ }
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};
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static int apple_wdt_probe(struct udevice *dev)
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{
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struct apple_wdt_priv *priv = dev_get_priv(dev);
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struct clk clk;
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int ret;
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priv->base = dev_read_addr_ptr(dev);
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if (!priv->base)
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return -EINVAL;
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ret = clk_get_by_index(dev, 0, &clk);
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if (ret)
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return ret;
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ret = clk_enable(&clk);
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if (ret)
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return ret;
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priv->clk_rate = clk_get_rate(&clk);
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return 0;
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}
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U_BOOT_DRIVER(apple_wdt) = {
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.name = "apple_wdt",
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.id = UCLASS_WDT,
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.of_match = apple_wdt_ids,
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.priv_auto = sizeof(struct apple_wdt_priv),
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.probe = apple_wdt_probe,
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.ops = &apple_wdt_ops,
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};
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