watchdog: Add Renesas R-Car Gen5 window watchdog driver

Add support of Renesas R-Car Gen5 window watchdog timer. Timeout
configuration is derived from CONFIG_WATCHDOG_TIMEOUT_MSECS, which
is more accurate than the 1-second granularity 'timeout' passed to
.start callback.

Reviewed-by: Stefan Roese <stefan.roese@mailbox.org>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 416d29d256a2db6e703057c9faeeea3b0272ba91..9ea617f1e435d42db68cffa67d71c31cf80e62b7 100644 (file)
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -356,6 +356,13 @@ config WDT_RENESAS
        help
          Enables Renesas SoC R8A779F0 watchdog timer support.
 
+config WDT_RENESAS_WWDT
+       bool "Renesas window watchdog timer support"
+       depends on WDT
+       select SYSCON
+       help
+         Enables Renesas window watchdog timer support.
+
 config WDT_SANDBOX
        bool "Enable Watchdog Timer support for Sandbox"
        depends on SANDBOX && WDT

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 02e2674f8af7250a846d724b4608a04a2152f7ae..84faefdb4c2844f6e0b0d2a1ba4ebe151c7395a7 100644 (file)
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_WDT_NPCM) += npcm_wdt.o
 obj-$(CONFIG_WDT_OCTEONTX) += octeontx_wdt.o
 obj-$(CONFIG_WDT_OMAP3) += omap_wdt.o
 obj-$(CONFIG_WDT_RENESAS) += renesas_wdt.o
+obj-$(CONFIG_WDT_RENESAS_WWDT) += renesas_wwdt.o
 obj-$(CONFIG_WDT_SBSA) += sbsa_gwdt.o
 obj-$(CONFIG_WDT_K3_RTI) += rti_wdt.o
 obj-$(CONFIG_WDT_SIEMENS_PMIC) += siemens_pmic_wdt.o

diff --git a/drivers/watchdog/renesas_wwdt.c b/drivers/watchdog/renesas_wwdt.c
new file mode 100644 (file)
index 0000000..f6f508c
--- /dev/null
+++ b/drivers/watchdog/renesas_wwdt.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2026 Marek Vasut <marek.vasut+renesas@mailbox.org>
+ */
+
+#include <asm/io.h>
+#include <clk.h>
+#include <dm/device_compat.h>
+#include <dm.h>
+#include <linux/bitfield.h>
+#include <linux/iopoll.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <wdt.h>
+
+#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
+
+#define RSIP_CTL_CFG4          0xc0
+#define RSIP_CTL_CFG4_OPWDEN   BIT(3)
+#define RSIP_CTL_CFG4_OPWDVAC  BIT(5)
+
+#define WDTA0_ACT_CODE         0xac
+#define WDTA0WDTE              0x0
+#define WDTA0EVAC              0x4
+#define WDTA0REF               0x8
+#define WDTA0MD                        0xc
+#define WDTA0MD_OVF_MASK       GENMASK(6, 4)
+#define WDTA0MD_OVF(n)         field_prep(WDTA0MD_OVF_MASK, (n))
+#define WDTA0MD_NWIE           BIT(3)
+#define WDTA0MD_NERM           BIT(2)
+#define WDTA0MD_NVS_MASK       GENMASK(1, 0)
+#define WDTA0MD_NVS_75P                FIELD_PREP(WDTA0MD_NVS_MASK, 3)
+
+struct wwdt_priv {
+       void __iomem *base;
+       struct regmap *ctl;
+       unsigned int timeout;
+};
+
+/**
+ * wwdt_reset() - Reset or ping Window WDT
+ * @dev: Watchdog device
+ */
+static int wwdt_reset(struct udevice *dev)
+{
+       struct wwdt_priv *priv = dev_get_priv(dev);
+       const u32 cfg = readl(priv->ctl->ranges[0].start + RSIP_CTL_CFG4);
+       u32 rv;
+
+       /* WDT disabled, do nothing. */
+       if (!(cfg & RSIP_CTL_CFG4_OPWDEN))
+               return 0;
+
+       /* WDT with variable activation code */
+       if (cfg & RSIP_CTL_CFG4_OPWDVAC) {
+               rv = readb(priv->base + WDTA0REF);
+               rv = WDTA0_ACT_CODE - rv;
+               writeb(rv, priv->base + WDTA0EVAC);
+       } else {
+               writeb(WDTA0_ACT_CODE, priv->base + WDTA0WDTE);
+       }
+
+       return 0;
+}
+
+/**
+ * wwdt_start() - Start Window WDT
+ * @dev: Watchdog device
+ * @timeout: Watchdog timeout (not used)
+ * @flags: Flags (not used)
+ */
+static int wwdt_start(struct udevice *dev, u64 timeout, ulong flags)
+{
+       struct wwdt_priv *priv = dev_get_priv(dev);
+
+       clrsetbits_8(priv->base + WDTA0MD,
+                    WDTA0MD_OVF_MASK | WDTA0MD_NWIE |
+                    WDTA0MD_NERM | WDTA0MD_NVS_MASK,
+                    WDTA0MD_OVF(priv->timeout) | WDTA0MD_NWIE |
+                    WDTA0MD_NVS_75P);
+
+       wwdt_reset(dev);
+
+       return 0;
+}
+
+/**
+ * wwdt_probe() - Initialize Window WDT hardware
+ * @dev: Watchdog device
+ */
+static int wwdt_probe(struct udevice *dev)
+{
+       struct wwdt_priv *priv = dev_get_priv(dev);
+       struct udevice *syscon;
+       unsigned long rate;
+       struct clk *clk;
+       int ret;
+
+       priv->base = dev_remap_addr(dev);
+       if (!priv->base)
+               return -EINVAL;
+
+       ret = uclass_get_device_by_phandle(UCLASS_SYSCON, dev, "syscon", &syscon);
+       if (ret) {
+               dev_err(dev, "Failed to get syscon\n");
+               return ret;
+       }
+
+       priv->ctl = syscon_get_regmap(syscon);
+       if (!priv->ctl) {
+               dev_err(dev, "Failed to get regmap\n");
+               return -ENODEV;
+       }
+
+       clk = devm_clk_get(dev, "cnt");
+       if (IS_ERR(clk)) {
+               ret = PTR_ERR(clk);
+               dev_err(dev, "Failed to get counter clock: %d\n", ret);
+               return ret;
+       }
+
+       ret = clk_enable(clk);
+       if (ret)
+               return ret;
+
+       rate = clk_get_rate(clk);
+       if (!rate) {
+               clk_disable(clk);
+               return -ENOENT;
+       }
+
+       /*
+        * Interval time is in "2^9..2^16 / clk_wdt" range. WDTA0OVFx is
+        * in 0..7 range. The code below does the WDTA0OVFx calculation
+        * from "interval_time = (1 << N) / clk_wdt" by caculating the N.
+        * The N rounded down is MSbit of (interval_time * clk_wdt). The
+        * result is then clamped to fit into the N in 9..16 range, and
+        * decremented by 9 to fit into WDTA0OVFx in 0..7 range .
+        */
+       priv->timeout = clamp(fls(CONFIG_WATCHDOG_TIMEOUT_MSECS * rate) - 1, 9, 16) - 9;
+
+       return 0;
+}
+
+static const struct wdt_ops wwdt_ops = {
+       .start = wwdt_start,
+       .reset = wwdt_reset,
+};
+
+static const struct udevice_id wwdt_ids[] = {
+       { .compatible = "renesas,rcar-gen5-wwdt" },
+       {}
+};
+
+U_BOOT_DRIVER(wwdt_renesas) = {
+       .name = "wwdt_renesas",
+       .id = UCLASS_WDT,
+       .of_match = wwdt_ids,
+       .ops = &wwdt_ops,
+       .probe  = wwdt_probe,
+       .priv_auto = sizeof(struct wwdt_priv),
+};