181 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (c) 2020 TOSHIBA CORPORATION4 * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation5 * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>6 */7 8#include <linux/clk.h>9#include <linux/io.h>10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/of.h>13#include <linux/platform_device.h>14#include <linux/watchdog.h>15 16#define WDT_CNT 0x0017#define WDT_MIN 0x0418#define WDT_MAX 0x0819#define WDT_CTL 0x0c20#define WDT_CMD 0x1021#define WDT_CMD_CLEAR 0x435222#define WDT_CMD_START_STOP 0x535423#define WDT_DIV 0x3024 25#define VISCONTI_WDT_FREQ 2000000 /* 2MHz */26#define WDT_DEFAULT_TIMEOUT 10U /* in seconds */27 28static bool nowayout = WATCHDOG_NOWAYOUT;29module_param(nowayout, bool, 0);30MODULE_PARM_DESC(31 nowayout,32 "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT)")");33 34struct visconti_wdt_priv {35 struct watchdog_device wdev;36 void __iomem *base;37 u32 div;38};39 40static int visconti_wdt_start(struct watchdog_device *wdev)41{42 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);43 u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;44 45 writel(priv->div, priv->base + WDT_DIV);46 writel(0, priv->base + WDT_MIN);47 writel(timeout, priv->base + WDT_MAX);48 writel(0, priv->base + WDT_CTL);49 writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);50 51 return 0;52}53 54static int visconti_wdt_stop(struct watchdog_device *wdev)55{56 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);57 58 writel(1, priv->base + WDT_CTL);59 writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);60 61 return 0;62}63 64static int visconti_wdt_ping(struct watchdog_device *wdd)65{66 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);67 68 writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);69 70 return 0;71}72 73static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)74{75 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);76 u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;77 u32 cnt = readl(priv->base + WDT_CNT);78 79 if (timeout <= cnt)80 return 0;81 timeout -= cnt;82 83 return timeout / VISCONTI_WDT_FREQ;84}85 86static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)87{88 u32 val;89 struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);90 91 wdev->timeout = timeout;92 val = wdev->timeout * VISCONTI_WDT_FREQ;93 94 /* Clear counter before setting timeout because WDT expires */95 writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);96 writel(val, priv->base + WDT_MAX);97 98 return 0;99}100 101static const struct watchdog_info visconti_wdt_info = {102 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,103 .identity = "Visconti Watchdog",104};105 106static const struct watchdog_ops visconti_wdt_ops = {107 .owner = THIS_MODULE,108 .start = visconti_wdt_start,109 .stop = visconti_wdt_stop,110 .ping = visconti_wdt_ping,111 .get_timeleft = visconti_wdt_get_timeleft,112 .set_timeout = visconti_wdt_set_timeout,113};114 115static int visconti_wdt_probe(struct platform_device *pdev)116{117 struct watchdog_device *wdev;118 struct visconti_wdt_priv *priv;119 struct device *dev = &pdev->dev;120 struct clk *clk;121 int ret;122 unsigned long clk_freq;123 124 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);125 if (!priv)126 return -ENOMEM;127 128 priv->base = devm_platform_ioremap_resource(pdev, 0);129 if (IS_ERR(priv->base))130 return PTR_ERR(priv->base);131 132 clk = devm_clk_get_enabled(dev, NULL);133 if (IS_ERR(clk))134 return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");135 136 clk_freq = clk_get_rate(clk);137 if (!clk_freq)138 return -EINVAL;139 140 priv->div = clk_freq / VISCONTI_WDT_FREQ;141 142 /* Initialize struct watchdog_device. */143 wdev = &priv->wdev;144 wdev->info = &visconti_wdt_info;145 wdev->ops = &visconti_wdt_ops;146 wdev->parent = dev;147 wdev->min_timeout = 1;148 wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;149 wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);150 151 watchdog_set_drvdata(wdev, priv);152 watchdog_set_nowayout(wdev, nowayout);153 watchdog_stop_on_unregister(wdev);154 155 /* This overrides the default timeout only if DT configuration was found */156 ret = watchdog_init_timeout(wdev, 0, dev);157 if (ret)158 dev_warn(dev, "Specified timeout value invalid, using default\n");159 160 return devm_watchdog_register_device(dev, wdev);161}162 163static const struct of_device_id visconti_wdt_of_match[] = {164 { .compatible = "toshiba,visconti-wdt", },165 {}166};167MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);168 169static struct platform_driver visconti_wdt_driver = {170 .driver = {171 .name = "visconti_wdt",172 .of_match_table = visconti_wdt_of_match,173 },174 .probe = visconti_wdt_probe,175};176module_platform_driver(visconti_wdt_driver);177 178MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");179MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");180MODULE_LICENSE("GPL v2");181