[RFC PATCH 7/9] watchdog: rzv2h: Add syscon support for RZ/T2H and RZ/N2H WDT control register
From: Prabhakar
Date: Mon May 11 2026 - 14:52:18 EST
From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
On RZ/T2H and RZ/N2H SoCs the WDTDCR register resides in the second
region of the System Controller (SYS) block at 0x81290000, which is
shared with other peripherals. A dedicated SYS driver now manages this
region and exposes it via a syscon regmap interface, making direct
mapping of the WDTDCR register by the WDT driver no longer viable.
Update the WDT driver to support both access methods to maintain
backward compatibility with old device trees that use direct mapping:
New binding (syscon):
reg = <0 0x80082800 0 0x400>;
renesas,sys = <&sys1 2>;
Old binding (direct mapping):
reg = <0 0x80082800 0 0x400>,
<0 0x81295108 0 0x04>;
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
drivers/watchdog/Kconfig | 1 +
drivers/watchdog/rzv2h_wdt.c | 96 +++++++++++++++++++++++++++++-------
2 files changed, 79 insertions(+), 18 deletions(-)
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 6a9695a16d5e..37b71e2cd1af 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1007,6 +1007,7 @@ config RENESAS_RZV2HWDT
depends on ARCH_RENESAS || COMPILE_TEST
depends on PM || COMPILE_TEST
select WATCHDOG_CORE
+ select MFD_SYSCON
help
This driver adds watchdog support for the integrated watchdogs in the
Renesas RZ/{G3E,V2H(P)} SoCs. These watchdogs can be used to reset a
diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index e9545b8f5fd0..e14ff853a4e9 100644
--- a/drivers/watchdog/rzv2h_wdt.c
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -8,10 +8,12 @@
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
#include <linux/reset.h>
#include <linux/units.h>
#include <linux/watchdog.h>
@@ -45,6 +47,10 @@
#define WDT_DEFAULT_TIMEOUT 60U
+#define RZT2H_WDT_MAX_INSTANCES 6
+
+#define RZT2H_WDTDCR_OFFSET(n) (0x5100 + (n) * 4)
+
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
@@ -65,6 +71,11 @@ struct rzv2h_of_data {
bool wdtdcr;
};
+struct rzv2h_sys_wdtdcr {
+ struct regmap *regmap;
+ unsigned int offset;
+};
+
struct rzv2h_wdt_priv {
void __iomem *base;
void __iomem *wdtdcr;
@@ -73,6 +84,7 @@ struct rzv2h_wdt_priv {
struct reset_control *rstc;
struct watchdog_device wdev;
const struct rzv2h_of_data *of_data;
+ struct rzv2h_sys_wdtdcr sysc;
};
static int rzv2h_wdt_ping(struct watchdog_device *wdev)
@@ -89,9 +101,18 @@ static int rzv2h_wdt_ping(struct watchdog_device *wdev)
return 0;
}
-static void rzt2h_wdt_wdtdcr_count_ctrl(struct rzv2h_wdt_priv *priv, bool start)
+static int rzt2h_wdt_wdtdcr_count_ctrl(struct rzv2h_wdt_priv *priv, bool start)
{
- u32 reg = readl(priv->wdtdcr + WDTDCR);
+ struct rzv2h_sys_wdtdcr *sysc = &priv->sysc;
+ u32 reg;
+
+ if (sysc->regmap) {
+ return regmap_update_bits(sysc->regmap, sysc->offset,
+ WDTDCR_WDTSTOPCTRL,
+ start ? 0 : WDTDCR_WDTSTOPCTRL);
+ }
+
+ reg = readl(priv->wdtdcr + WDTDCR);
if (start)
reg &= ~WDTDCR_WDTSTOPCTRL;
@@ -99,16 +120,18 @@ static void rzt2h_wdt_wdtdcr_count_ctrl(struct rzv2h_wdt_priv *priv, bool start)
reg |= WDTDCR_WDTSTOPCTRL;
writel(reg, priv->wdtdcr + WDTDCR);
+
+ return 0;
}
-static void rzt2h_wdt_wdtdcr_count_stop(struct rzv2h_wdt_priv *priv)
+static int rzt2h_wdt_wdtdcr_count_stop(struct rzv2h_wdt_priv *priv)
{
- rzt2h_wdt_wdtdcr_count_ctrl(priv, false);
+ return rzt2h_wdt_wdtdcr_count_ctrl(priv, false);
}
-static void rzt2h_wdt_wdtdcr_count_start(struct rzv2h_wdt_priv *priv)
+static int rzt2h_wdt_wdtdcr_count_start(struct rzv2h_wdt_priv *priv)
{
- rzt2h_wdt_wdtdcr_count_ctrl(priv, true);
+ return rzt2h_wdt_wdtdcr_count_ctrl(priv, true);
}
static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
@@ -158,8 +181,14 @@ static int rzv2h_wdt_start(struct watchdog_device *wdev)
rzv2h_wdt_setup(wdev, of_data->cks_max | WDTCR_RPSS_100 |
WDTCR_RPES_0 | of_data->tops);
- if (priv->of_data->wdtdcr)
- rzt2h_wdt_wdtdcr_count_start(priv);
+ if (priv->of_data->wdtdcr) {
+ ret = rzt2h_wdt_wdtdcr_count_start(priv);
+ if (ret) {
+ reset_control_assert(priv->rstc);
+ pm_runtime_put(wdev->parent);
+ return ret;
+ }
+ }
/*
* Down counting starts after writing the sequence 00h -> FFh to the
@@ -179,8 +208,13 @@ static int rzv2h_wdt_stop(struct watchdog_device *wdev)
if (ret)
return ret;
- if (priv->of_data->wdtdcr)
- rzt2h_wdt_wdtdcr_count_stop(priv);
+ if (priv->of_data->wdtdcr) {
+ ret = rzt2h_wdt_wdtdcr_count_stop(priv);
+ if (ret) {
+ reset_control_deassert(priv->rstc);
+ return ret;
+ }
+ }
pm_runtime_put(wdev->parent);
@@ -196,9 +230,10 @@ static int rzv2h_wdt_restart(struct watchdog_device *wdev,
unsigned long action, void *data)
{
struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ bool active = watchdog_active(wdev);
int ret;
- if (!watchdog_active(wdev)) {
+ if (!active) {
ret = clk_enable(priv->pclk);
if (ret)
return ret;
@@ -242,8 +277,17 @@ static int rzv2h_wdt_restart(struct watchdog_device *wdev,
rzv2h_wdt_setup(wdev, priv->of_data->cks_min | WDTCR_RPSS_25 |
WDTCR_RPES_75 | WDTCR_TOPS_1024);
- if (priv->of_data->wdtdcr)
- rzt2h_wdt_wdtdcr_count_start(priv);
+ if (priv->of_data->wdtdcr) {
+ ret = rzt2h_wdt_wdtdcr_count_start(priv);
+ if (ret) {
+ if (!active) {
+ reset_control_assert(priv->rstc);
+ clk_disable(priv->oscclk);
+ clk_disable(priv->pclk);
+ }
+ return ret;
+ }
+ }
rzv2h_wdt_ping(wdev);
@@ -264,21 +308,37 @@ static const struct watchdog_ops rzv2h_wdt_ops = {
static int rzt2h_wdt_wdtdcr_init(struct platform_device *pdev,
struct rzv2h_wdt_priv *priv)
{
+ struct device_node *np = pdev->dev.of_node;
int ret;
- priv->wdtdcr = devm_platform_ioremap_resource(pdev, 1);
- if (IS_ERR(priv->wdtdcr))
- return PTR_ERR(priv->wdtdcr);
+ if (of_property_present(np, "renesas,sys")) {
+ struct rzv2h_sys_wdtdcr *sysc = &priv->sysc;
+ unsigned int wdt_index;
+
+ sysc->regmap = syscon_regmap_lookup_by_phandle_args(np, "renesas,sys",
+ 1, &wdt_index);
+ if (IS_ERR(sysc->regmap))
+ return PTR_ERR(sysc->regmap);
+
+ if (wdt_index >= RZT2H_WDT_MAX_INSTANCES)
+ return -EINVAL;
+
+ sysc->offset = RZT2H_WDTDCR_OFFSET(wdt_index);
+ } else {
+ priv->wdtdcr = devm_platform_ioremap_resource(pdev, 1);
+ if (IS_ERR(priv->wdtdcr))
+ return PTR_ERR(priv->wdtdcr);
+ }
ret = pm_runtime_resume_and_get(&pdev->dev);
if (ret)
return ret;
- rzt2h_wdt_wdtdcr_count_stop(priv);
+ ret = rzt2h_wdt_wdtdcr_count_stop(priv);
pm_runtime_put(&pdev->dev);
- return 0;
+ return ret;
}
static int rzv2h_wdt_probe(struct platform_device *pdev)
--
2.54.0