linux-kernel - [PATCH v3 5/6] watchdog: rzv2h_wdt: Add support to retrieve the bootstatus information

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250113112349.801875-6-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Mon, 13 Jan 2025 11:23:48 +0000
From: Prabhakar <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert+renesas@...der.be>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Wim Van Sebroeck <wim@...ux-watchdog.org>,
	Guenter Roeck <linux@...ck-us.net>,
	Magnus Damm <magnus.damm@...il.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: linux-renesas-soc@...r.kernel.org,
	linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-watchdog@...r.kernel.org,
	Prabhakar <prabhakar.csengg@...il.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH v3 5/6] watchdog: rzv2h_wdt: Add support to retrieve the bootstatus information

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

On the RZ/V2H(P) SoC we can determine if the current boot is due to
`Power-on-Reset` or due to the `Watchdog`. The information used to
determine this is present on the CPG block.

The CPG_ERROR_RSTm(m = 2 - 8) registers are set in response to an error
interrupt causing an reset. CPG_ERROR_RST2[ERROR_RST0/1/2] is set if there
was an underflow/overflow on WDT1 causing an error interrupt.

To fetch this information from CPG block `syscon` is used and bootstatus
field in the watchdog device is updated based on the
CPG_ERROR_RST2[ERROR_RST0/1/2] bit. Upon consumig
CPG_ERROR_RST2[ERROR_RST0/1/2] bit we clear it.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
Note, this change doesnt break any ABI, if the `syscon` node is missing
the driver probe continues further to handle backward compatibility.

v2->v3
- No change

v1->v2
- Returned ret in error path instead of -EINVAL
- Dropped unnecessar regmap_read
---
 drivers/watchdog/rzv2h_wdt.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index 8defd0241213..ab7e35928190 100644
--- a/drivers/watchdog/rzv2h_wdt.c
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -4,14 +4,17 @@
  *
  * Copyright (C) 2024 Renesas Electronics Corporation.
  */
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #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>
@@ -40,6 +43,9 @@
 
 #define WDT_DEFAULT_TIMEOUT	60U
 
+#define CPG_ERROR_RST2(x)	BIT(x)
+#define CPG_ERROR_RST2_WEN(x)	BIT((x) + 16)
+
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
@@ -206,9 +212,37 @@ static const struct watchdog_ops rzv2h_wdt_ops = {
 static int rzv2h_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
 	struct rzv2h_wdt_priv *priv;
+	unsigned int bootstatus = 0;
+	struct regmap *syscon;
 	int ret;
 
+	/* Do not error out to maintain old DT compatibility */
+	syscon = syscon_regmap_lookup_by_phandle(np, "renesas,syscon-cpg-error-rst");
+	if (!IS_ERR(syscon)) {
+		struct of_phandle_args args;
+		u32 reg;
+
+		ret = of_parse_phandle_with_fixed_args(np, "renesas,syscon-cpg-error-rst",
+						       2, 0, &args);
+		if (ret)
+			return ret;
+
+		ret = regmap_read(syscon, args.args[0], &reg);
+		if (ret)
+			return ret;
+
+		if (reg & CPG_ERROR_RST2(args.args[1])) {
+			ret = regmap_write(syscon, args.args[0],
+					   CPG_ERROR_RST2(args.args[1]) |
+					   CPG_ERROR_RST2_WEN(args.args[1]));
+			if (ret)
+				return ret;
+		}
+		bootstatus = reg & CPG_ERROR_RST2(args.args[1]) ? WDIOF_CARDRESET : 0;
+	}
+
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
@@ -243,6 +277,7 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 	priv->wdev.info = &rzv2h_wdt_ident;
 	priv->wdev.ops = &rzv2h_wdt_ops;
 	priv->wdev.parent = dev;
+	priv->wdev.bootstatus = bootstatus;
 	watchdog_set_drvdata(&priv->wdev, priv);
 	watchdog_set_nowayout(&priv->wdev, nowayout);
 	watchdog_stop_on_unregister(&priv->wdev);
-- 
2.43.0