linux-kernel - [RFC PATCH] 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-next>] [day] [month] [year] [list]
Message-ID: <20241213174419.908525-1-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Fri, 13 Dec 2024 17:44:19 +0000
From: Prabhakar <prabhakar.csengg@...il.com>
To: Wim Van Sebroeck <wim@...ux-watchdog.org>,
	Guenter Roeck <linux@...ck-us.net>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Rob Herring <robh@...nel.org>,
	linux-watchdog@...r.kernel.org
Cc: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-renesas-soc@...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: [RFC PATCH] 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_RST1] 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_RST1] bit. Upon consumig CPG_ERROR_RST2[ERROR_RST1]
bit we are also clearing it.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
@Geert, I intend to drop WDT0/2/3 nodes (and related clocks) as HW manual
says WDT1 is for CA55 (I'll first confirm this internally)

Hi Geert/Rob,

I havent included a binding changes as part of the RFC as I wanted to get
some initial feedback on the implementation. Currently CPG block doesnt
have the "syscon" this patch has been tested with below diff to SoC DTSI

Cheers,
Prabhakar

Changes to SoC DTSI:
@@ -243,7 +243,7 @@ pinctrl: pinctrl@...10000 {
                };

                cpg: clock-controller@...20000 {
-                       compatible = "renesas,r9a09g057-cpg";
+                       compatible = "renesas,r9a09g057-cpg", "syscon";
                        reg = <0 0x10420000 0 0x10000>;
                        clocks = <&audio_extal_clk>, <&rtxin_clk>, <&qextal_clk>;
                        clock-names = "audio_extal", "rtxin", "qextal";
@@ -455,6 +456,7 @@ wdt1: watchdog@...00000 {
                        clock-names = "pclk", "oscclk";
                        resets = <&cpg 0x76>;
                        power-domains = <&cpg>;
+                       syscon = <&cpg>;
                        status = "disabled";
                };

---
 drivers/watchdog/rzv2h_wdt.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index 8defd0241213..8e0901bb7d2b 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 +43,10 @@
 
 #define WDT_DEFAULT_TIMEOUT	60U
 
+#define CPG_ERROR_RST2			0xb40
+#define CPG_ERROR_RST2_ERR_RST1		BIT(1)
+#define CPG_ERROR_RST2_ERR_RST1_WEN	(BIT(1) << 16)
+
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
@@ -135,7 +142,7 @@ static int rzv2h_wdt_stop(struct watchdog_device *wdev)
 }
 
 static const struct watchdog_info rzv2h_wdt_ident = {
-	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_CARDRESET,
 	.identity = "Renesas RZ/V2H WDT Watchdog",
 };
 
@@ -207,12 +214,29 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rzv2h_wdt_priv *priv;
+	struct regmap *regmap;
+	unsigned int buf;
 	int ret;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
+	regmap = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, CPG_ERROR_RST2, &buf);
+	if (ret)
+		return -EINVAL;
+
+	if (buf & CPG_ERROR_RST2_ERR_RST1) {
+		ret = regmap_write(regmap, CPG_ERROR_RST2,
+				   CPG_ERROR_RST2_ERR_RST1_WEN | CPG_ERROR_RST2_ERR_RST1);
+		if (ret)
+			return -EINVAL;
+	}
+
 	priv->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
@@ -243,6 +267,7 @@ 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 = buf & CPG_ERROR_RST2_ERR_RST1 ? WDIOF_CARDRESET : 0;
 	watchdog_set_drvdata(&priv->wdev, priv);
 	watchdog_set_nowayout(&priv->wdev, nowayout);
 	watchdog_stop_on_unregister(&priv->wdev);
-- 
2.43.0