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341 lines
9.2 KiB
C
341 lines
9.2 KiB
C
/*
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* Copyright 2016 IBM Corporation
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*
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* Joel Stanley <joel@jms.id.au>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/watchdog.h>
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struct aspeed_wdt {
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struct watchdog_device wdd;
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void __iomem *base;
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u32 ctrl;
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};
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struct aspeed_wdt_config {
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u32 ext_pulse_width_mask;
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};
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static const struct aspeed_wdt_config ast2400_config = {
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.ext_pulse_width_mask = 0xff,
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};
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static const struct aspeed_wdt_config ast2500_config = {
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.ext_pulse_width_mask = 0xfffff,
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};
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static const struct of_device_id aspeed_wdt_of_table[] = {
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{ .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config },
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{ .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config },
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{ },
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};
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MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
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#define WDT_STATUS 0x00
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#define WDT_RELOAD_VALUE 0x04
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#define WDT_RESTART 0x08
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#define WDT_CTRL 0x0C
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#define WDT_CTRL_BOOT_SECONDARY BIT(7)
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#define WDT_CTRL_RESET_MODE_SOC (0x00 << 5)
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#define WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5)
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#define WDT_CTRL_RESET_MODE_ARM_CPU (0x10 << 5)
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#define WDT_CTRL_1MHZ_CLK BIT(4)
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#define WDT_CTRL_WDT_EXT BIT(3)
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#define WDT_CTRL_WDT_INTR BIT(2)
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#define WDT_CTRL_RESET_SYSTEM BIT(1)
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#define WDT_CTRL_ENABLE BIT(0)
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/*
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* WDT_RESET_WIDTH controls the characteristics of the external pulse (if
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* enabled), specifically:
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*
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* * Pulse duration
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* * Drive mode: push-pull vs open-drain
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* * Polarity: Active high or active low
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*
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* Pulse duration configuration is available on both the AST2400 and AST2500,
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* though the field changes between SoCs:
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*
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* AST2400: Bits 7:0
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* AST2500: Bits 19:0
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*
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* This difference is captured in struct aspeed_wdt_config.
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*
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* The AST2500 exposes the drive mode and polarity options, but not in a
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* regular fashion. For read purposes, bit 31 represents active high or low,
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* and bit 30 represents push-pull or open-drain. With respect to write, magic
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* values need to be written to the top byte to change the state of the drive
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* mode and polarity bits. Any other value written to the top byte has no
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* effect on the state of the drive mode or polarity bits. However, the pulse
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* width value must be preserved (as desired) if written.
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*/
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#define WDT_RESET_WIDTH 0x18
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#define WDT_RESET_WIDTH_ACTIVE_HIGH BIT(31)
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#define WDT_ACTIVE_HIGH_MAGIC (0xA5 << 24)
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#define WDT_ACTIVE_LOW_MAGIC (0x5A << 24)
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#define WDT_RESET_WIDTH_PUSH_PULL BIT(30)
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#define WDT_PUSH_PULL_MAGIC (0xA8 << 24)
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#define WDT_OPEN_DRAIN_MAGIC (0x8A << 24)
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#define WDT_RESTART_MAGIC 0x4755
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/* 32 bits at 1MHz, in milliseconds */
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#define WDT_MAX_TIMEOUT_MS 4294967
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#define WDT_DEFAULT_TIMEOUT 30
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#define WDT_RATE_1MHZ 1000000
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static struct aspeed_wdt *to_aspeed_wdt(struct watchdog_device *wdd)
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{
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return container_of(wdd, struct aspeed_wdt, wdd);
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}
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static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count)
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{
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wdt->ctrl |= WDT_CTRL_ENABLE;
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writel(0, wdt->base + WDT_CTRL);
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writel(count, wdt->base + WDT_RELOAD_VALUE);
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writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
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writel(wdt->ctrl, wdt->base + WDT_CTRL);
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}
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static int aspeed_wdt_start(struct watchdog_device *wdd)
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{
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struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
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aspeed_wdt_enable(wdt, wdd->timeout * WDT_RATE_1MHZ);
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return 0;
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}
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static int aspeed_wdt_stop(struct watchdog_device *wdd)
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{
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struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
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wdt->ctrl &= ~WDT_CTRL_ENABLE;
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writel(wdt->ctrl, wdt->base + WDT_CTRL);
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return 0;
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}
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static int aspeed_wdt_ping(struct watchdog_device *wdd)
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{
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struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
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writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
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return 0;
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}
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static int aspeed_wdt_set_timeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
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u32 actual;
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wdd->timeout = timeout;
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actual = min(timeout, wdd->max_hw_heartbeat_ms * 1000);
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writel(actual * WDT_RATE_1MHZ, wdt->base + WDT_RELOAD_VALUE);
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writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
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return 0;
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}
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static int aspeed_wdt_restart(struct watchdog_device *wdd,
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unsigned long action, void *data)
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{
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struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
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wdt->ctrl &= ~WDT_CTRL_BOOT_SECONDARY;
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aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000);
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mdelay(1000);
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return 0;
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}
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static const struct watchdog_ops aspeed_wdt_ops = {
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.start = aspeed_wdt_start,
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.stop = aspeed_wdt_stop,
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.ping = aspeed_wdt_ping,
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.set_timeout = aspeed_wdt_set_timeout,
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.restart = aspeed_wdt_restart,
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.owner = THIS_MODULE,
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};
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static const struct watchdog_info aspeed_wdt_info = {
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.options = WDIOF_KEEPALIVEPING
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| WDIOF_MAGICCLOSE
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| WDIOF_SETTIMEOUT,
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.identity = KBUILD_MODNAME,
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};
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static int aspeed_wdt_probe(struct platform_device *pdev)
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{
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const struct aspeed_wdt_config *config;
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const struct of_device_id *ofdid;
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struct aspeed_wdt *wdt;
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struct resource *res;
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struct device_node *np;
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const char *reset_type;
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u32 duration;
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int ret;
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wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
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if (!wdt)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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wdt->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(wdt->base))
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return PTR_ERR(wdt->base);
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/*
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* The ast2400 wdt can run at PCLK, or 1MHz. The ast2500 only
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* runs at 1MHz. We chose to always run at 1MHz, as there's no
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* good reason to have a faster watchdog counter.
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*/
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wdt->wdd.info = &aspeed_wdt_info;
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wdt->wdd.ops = &aspeed_wdt_ops;
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wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
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wdt->wdd.parent = &pdev->dev;
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wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
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watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
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np = pdev->dev.of_node;
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ofdid = of_match_node(aspeed_wdt_of_table, np);
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if (!ofdid)
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return -EINVAL;
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config = ofdid->data;
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wdt->ctrl = WDT_CTRL_1MHZ_CLK;
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/*
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* Control reset on a per-device basis to ensure the
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* host is not affected by a BMC reboot
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*/
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ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
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if (ret) {
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wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
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} else {
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if (!strcmp(reset_type, "cpu"))
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wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU |
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WDT_CTRL_RESET_SYSTEM;
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else if (!strcmp(reset_type, "soc"))
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wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC |
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WDT_CTRL_RESET_SYSTEM;
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else if (!strcmp(reset_type, "system"))
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wdt->ctrl |= WDT_CTRL_RESET_MODE_FULL_CHIP |
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WDT_CTRL_RESET_SYSTEM;
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else if (strcmp(reset_type, "none"))
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return -EINVAL;
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}
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if (of_property_read_bool(np, "aspeed,external-signal"))
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wdt->ctrl |= WDT_CTRL_WDT_EXT;
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if (of_property_read_bool(np, "aspeed,alt-boot"))
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wdt->ctrl |= WDT_CTRL_BOOT_SECONDARY;
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if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) {
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/*
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* The watchdog is running, but invoke aspeed_wdt_start() to
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* write wdt->ctrl to WDT_CTRL to ensure the watchdog's
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* configuration conforms to the driver's expectations.
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* Primarily, ensure we're using the 1MHz clock source.
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*/
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aspeed_wdt_start(&wdt->wdd);
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set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
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}
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if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
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u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
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reg &= config->ext_pulse_width_mask;
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if (of_property_read_bool(np, "aspeed,ext-push-pull"))
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reg |= WDT_PUSH_PULL_MAGIC;
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else
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reg |= WDT_OPEN_DRAIN_MAGIC;
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writel(reg, wdt->base + WDT_RESET_WIDTH);
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reg &= config->ext_pulse_width_mask;
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if (of_property_read_bool(np, "aspeed,ext-active-high"))
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reg |= WDT_ACTIVE_HIGH_MAGIC;
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else
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reg |= WDT_ACTIVE_LOW_MAGIC;
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writel(reg, wdt->base + WDT_RESET_WIDTH);
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}
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if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
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u32 max_duration = config->ext_pulse_width_mask + 1;
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if (duration == 0 || duration > max_duration) {
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dev_err(&pdev->dev, "Invalid pulse duration: %uus\n",
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duration);
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duration = max(1U, min(max_duration, duration));
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dev_info(&pdev->dev, "Pulse duration set to %uus\n",
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duration);
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}
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/*
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* The watchdog is always configured with a 1MHz source, so
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* there is no need to scale the microsecond value. However we
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* need to offset it - from the datasheet:
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*
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* "This register decides the asserting duration of wdt_ext and
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* wdt_rstarm signal. The default value is 0xFF. It means the
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* default asserting duration of wdt_ext and wdt_rstarm is
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* 256us."
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*
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* This implies a value of 0 gives a 1us pulse.
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*/
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writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
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}
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ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
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if (ret) {
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dev_err(&pdev->dev, "failed to register\n");
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return ret;
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}
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return 0;
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}
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static struct platform_driver aspeed_watchdog_driver = {
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.probe = aspeed_wdt_probe,
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.driver = {
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.name = KBUILD_MODNAME,
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.of_match_table = of_match_ptr(aspeed_wdt_of_table),
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},
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};
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static int __init aspeed_wdt_init(void)
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{
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return platform_driver_register(&aspeed_watchdog_driver);
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}
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arch_initcall(aspeed_wdt_init);
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static void __exit aspeed_wdt_exit(void)
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{
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platform_driver_unregister(&aspeed_watchdog_driver);
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}
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module_exit(aspeed_wdt_exit);
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MODULE_DESCRIPTION("Aspeed Watchdog Driver");
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MODULE_LICENSE("GPL");
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