// SPDX-License-Identifier: GPL-2.0
/*
* Renesas RZ/V2H(P) WDT Watchdog Driver
*
* Copyright (C) 2024 Renesas Electronics Corporation.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/units.h>
#include <linux/watchdog.h>
#define WDTRR 0x00 /* WDT Refresh Register RW, 8 */
#define WDTCR 0x02 /* WDT Control Register RW, 16 */
#define WDTSR 0x04 /* WDT Status Register RW, 16 */
#define WDTRCR 0x06 /* WDT Reset Control Register RW, 8 */
#define WDTCR_TOPS_1024 0x00
#define WDTCR_TOPS_16384 0x03
#define WDTCR_CKS_CLK_1 0x00
#define WDTCR_CKS_CLK_256 0x50
#define WDTCR_RPES_0 0x300
#define WDTCR_RPES_75 0x000
#define WDTCR_RPSS_25 0x00
#define WDTCR_RPSS_100 0x3000
#define WDTRCR_RSTIRQS BIT(7)
#define MAX_TIMEOUT_CYCLES 16384
#define CLOCK_DIV_BY_256 256
#define WDT_DEFAULT_TIMEOUT 60U
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
struct rzv2h_wdt_priv {
void __iomem *base;
struct clk *pclk;
struct clk *oscclk;
struct reset_control *rstc;
struct watchdog_device wdev;
};
static int rzv2h_wdt_ping(struct watchdog_device *wdev)
{
struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
/*
* The down-counter is refreshed and starts counting operation on
* a write of the values 00h and FFh to the WDTRR register.
*/
writeb(0x0, priv->base + WDTRR);
writeb(0xFF, priv->base + WDTRR);
return 0;
}
static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
{
struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
/* Configure the timeout, clock division ratio, and window start and end positions. */
writew(wdtcr, priv->base + WDTCR);
/* Enable interrupt output to the ICU. */
writeb(0, priv->base + WDTRCR);
/* Clear underflow flag and refresh error flag. */
writew(0, priv->base + WDTSR);
}
static int rzv2h_wdt_start(struct watchdog_device *wdev)
{
struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
int ret;
ret = pm_runtime_resume_and_get(wdev->parent);
if (ret)
return ret;
ret = reset_control_deassert(priv->rstc);
if (ret) {
pm_runtime_put(wdev->parent);
return ret;
}
/* delay to handle clock halt after de-assert operation */
udelay(3);
/*
* WDTCR
* - CKS[7:4] - Clock Division Ratio Select - 0101b: oscclk/256
* - RPSS[13:12] - Window Start Position Select - 11b: 100%
* - RPES[9:8] - Window End Position Select - 11b: 0%
* - TOPS[1:0] - Timeout Period Select - 11b: 16384 cycles (3FFFh)
*/
rzv2h_wdt_setup(wdev, WDTCR_CKS_CLK_256 | WDTCR_RPSS_100 |
WDTCR_RPES_0 | WDTCR_TOPS_16384);
/*
* Down counting starts after writing the sequence 00h -> FFh to the
* WDTRR register. Hence, call the ping operation after loading the counter.
*/
rzv2h_wdt_ping(wdev);
return 0;
}
static int rzv2h_wdt_stop(struct watchdog_device *wdev)
{
struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
int ret;
ret = reset_control_assert(priv->rstc);
if (ret)
return ret;
ret = pm_runtime_put(wdev->parent);
if (ret < 0)
return ret;
return 0;
}
static const struct watchdog_info rzv2h_wdt_ident = {
.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
.identity = "Renesas RZ/V2H WDT Watchdog",
};
static int rzv2h_wdt_restart(struct watchdog_device *wdev,
unsigned long action, void *data)
{
struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
int ret;
if (!watchdog_active(wdev)) {
ret = clk_enable(priv->pclk);
if (ret)
return ret;
ret = clk_enable(priv->oscclk);
if (ret) {
clk_disable(priv->pclk);
return ret;
}
ret = reset_control_deassert(priv->rstc);
if (ret) {
clk_disable(priv->oscclk);
clk_disable(priv->pclk);
return ret;
}
} else {
/*
* Writing to the WDT Control Register (WDTCR) or WDT Reset
* Control Register (WDTRCR) is possible once between the
* release from the reset state and the first refresh operation.
* Therefore, issue a reset if the watchdog is active.
*/
ret = reset_control_reset(priv->rstc);
if (ret)
return ret;
}
/* delay to handle clock halt after de-assert operation */
udelay(3);
/*
* WDTCR
* - CKS[7:4] - Clock Division Ratio Select - 0000b: oscclk/1
* - RPSS[13:12] - Window Start Position Select - 00b: 25%
* - RPES[9:8] - Window End Position Select - 00b: 75%
* - TOPS[1:0] - Timeout Period Select - 00b: 1024 cycles (03FFh)
*/
rzv2h_wdt_setup(wdev, WDTCR_CKS_CLK_1 | WDTCR_RPSS_25 |
WDTCR_RPES_75 | WDTCR_TOPS_1024);
rzv2h_wdt_ping(wdev);
/* wait for underflow to trigger... */
udelay(5);
return 0;
}
static const struct watchdog_ops rzv2h_wdt_ops = {
.owner = THIS_MODULE,
.start = rzv2h_wdt_start,
.stop = rzv2h_wdt_stop,
.ping = rzv2h_wdt_ping,
.restart = rzv2h_wdt_restart,
};
static int rzv2h_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct rzv2h_wdt_priv *priv;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
priv->pclk = devm_clk_get_prepared(&pdev->dev, "pclk");
if (IS_ERR(priv->pclk))
return dev_err_probe(&pdev->dev, PTR_ERR(priv->pclk), "no pclk");
priv->oscclk = devm_clk_get_prepared(&pdev->dev, "oscclk");
if (IS_ERR(priv->oscclk))
return dev_err_probe(&pdev->dev, PTR_ERR(priv->oscclk), "no oscclk");
priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
if (IS_ERR(priv->rstc))
return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
"failed to get cpg reset");
priv->wdev.max_hw_heartbeat_ms = (MILLI * MAX_TIMEOUT_CYCLES * CLOCK_DIV_BY_256) /
clk_get_rate(priv->oscclk);
dev_dbg(dev, "max hw timeout of %dms\n", priv->wdev.max_hw_heartbeat_ms);
ret = devm_pm_runtime_enable(&pdev->dev);
if (ret)
return ret;
priv->wdev.min_timeout = 1;
priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
priv->wdev.info = &rzv2h_wdt_ident;
priv->wdev.ops = &rzv2h_wdt_ops;
priv->wdev.parent = dev;
watchdog_set_drvdata(&priv->wdev, priv);
watchdog_set_nowayout(&priv->wdev, nowayout);
watchdog_stop_on_unregister(&priv->wdev);
ret = watchdog_init_timeout(&priv->wdev, 0, dev);
if (ret)
dev_warn(dev, "Specified timeout invalid, using default");
return devm_watchdog_register_device(&pdev->dev, &priv->wdev);
}
static const struct of_device_id rzv2h_wdt_ids[] = {
{ .compatible = "renesas,r9a09g057-wdt", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rzv2h_wdt_ids);
static struct platform_driver rzv2h_wdt_driver = {
.driver = {
.name = "rzv2h_wdt",
.of_match_table = rzv2h_wdt_ids,
},
.probe = rzv2h_wdt_probe,
};
module_platform_driver(rzv2h_wdt_driver);
MODULE_AUTHOR("Lad Prabhakar <[email protected]>");
MODULE_DESCRIPTION("Renesas RZ/V2H(P) WDT Watchdog Driver");
MODULE_LICENSE("GPL");
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