// SPDX-License-Identifier: GPL-2.0-only /* * Imagination Technologies PowerDown Controller Watchdog Timer. * * Copyright (c) 2014 Imagination Technologies Ltd. * * Based on drivers/watchdog/sunxi_wdt.c Copyright (c) 2013 Carlo Caione * 2012 Henrik Nordstrom * * Notes * ----- * The timeout value is rounded to the next power of two clock cycles. * This is configured using the PDC_WDT_CONFIG register, according to this * formula: * * timeout = 2^(delay + 1) clock cycles * * Where 'delay' is the value written in PDC_WDT_CONFIG register. * * Therefore, the hardware only allows to program watchdog timeouts, expressed * as a power of two number of watchdog clock cycles. The current implementation * guarantees that the actual watchdog timeout will be _at least_ the value * programmed in the imgpdg_wdt driver. * * The following table shows how the user-configured timeout relates * to the actual hardware timeout (watchdog clock @ 40000 Hz): * * input timeout | WD_DELAY | actual timeout * ----------------------------------- * 10 | 18 | 13 seconds * 20 | 19 | 26 seconds * 30 | 20 | 52 seconds * 60 | 21 | 104 seconds * * Albeit coarse, this granularity would suffice most watchdog uses. * If the platform allows it, the user should be able to change the watchdog * clock rate and achieve a finer timeout granularity. */ #include <linux/clk.h> #include <linux/io.h> #include <linux/log2.h> #include <linux/module.h> #include <linux/mod_devicetable.h> #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/watchdog.h> /* registers */ #define PDC_WDT_SOFT_RESET … #define PDC_WDT_CONFIG … #define PDC_WDT_CONFIG_ENABLE … #define PDC_WDT_CONFIG_DELAY_MASK … #define PDC_WDT_TICKLE1 … #define PDC_WDT_TICKLE1_MAGIC … #define PDC_WDT_TICKLE2 … #define PDC_WDT_TICKLE2_MAGIC … #define PDC_WDT_TICKLE_STATUS_MASK … #define PDC_WDT_TICKLE_STATUS_SHIFT … #define PDC_WDT_TICKLE_STATUS_HRESET … #define PDC_WDT_TICKLE_STATUS_TIMEOUT … #define PDC_WDT_TICKLE_STATUS_TICKLE … #define PDC_WDT_TICKLE_STATUS_SRESET … #define PDC_WDT_TICKLE_STATUS_USER … /* Timeout values are in seconds */ #define PDC_WDT_MIN_TIMEOUT … #define PDC_WDT_DEF_TIMEOUT … static int heartbeat; module_param(heartbeat, int, 0); MODULE_PARM_DESC(…) …; static bool nowayout = … WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(…) …; struct pdc_wdt_dev { … }; static int pdc_wdt_keepalive(struct watchdog_device *wdt_dev) { … } static int pdc_wdt_stop(struct watchdog_device *wdt_dev) { … } static void __pdc_wdt_set_timeout(struct pdc_wdt_dev *wdt) { … } static int pdc_wdt_set_timeout(struct watchdog_device *wdt_dev, unsigned int new_timeout) { … } /* Start the watchdog timer (delay should already be set) */ static int pdc_wdt_start(struct watchdog_device *wdt_dev) { … } static int pdc_wdt_restart(struct watchdog_device *wdt_dev, unsigned long action, void *data) { … } static const struct watchdog_info pdc_wdt_info = …; static const struct watchdog_ops pdc_wdt_ops = …; static int pdc_wdt_probe(struct platform_device *pdev) { … } static const struct of_device_id pdc_wdt_match[] = …; MODULE_DEVICE_TABLE(of, pdc_wdt_match); static struct platform_driver pdc_wdt_driver = …; module_platform_driver(…) …; MODULE_AUTHOR(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …;
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