Patch "watchdog: rzg2l_wdt: Handle TYPE-B reset for RZ/V2M" has been added to the 6.2-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    watchdog: rzg2l_wdt: Handle TYPE-B reset for RZ/V2M

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     watchdog-rzg2l_wdt-handle-type-b-reset-for-rz-v2m.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7929ec46970ac1c3ddb6d5df8be66ea2262af507
Author: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
Date:   Thu Nov 17 11:49:07 2022 +0000

    watchdog: rzg2l_wdt: Handle TYPE-B reset for RZ/V2M
    
    [ Upstream commit f769f97917c1e756e12ff042a93f6e3167254b5b ]
    
    As per section 48.4 of the HW User Manual, IPs in the RZ/V2M
    SoC need either a TYPE-A reset sequence or a TYPE-B reset
    sequence. More specifically, the watchdog IP needs a TYPE-B
    reset sequence.
    
    If the proper reset sequence isn't implemented, then resetting
    IPs may lead to undesired behaviour. In the restart callback of
    the watchdog driver the reset has basically no effect on the
    desired funcionality, as the register writes following the reset
    happen before the IP manages to come out of reset.
    
    Implement the TYPE-B reset sequence in the watchdog driver to
    address the issues with the restart callback on RZ/V2M.
    
    Fixes: ec122fd94eeb ("watchdog: rzg2l_wdt: Add rzv2m support")
    Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
    Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
    Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20221117114907.138583-3-fabrizio.castro.jz@xxxxxxxxxxx
    Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
    Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
index ceca42db08374..d404953d0e0f4 100644
--- a/drivers/watchdog/rzg2l_wdt.c
+++ b/drivers/watchdog/rzg2l_wdt.c
@@ -8,6 +8,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
@@ -35,6 +36,8 @@
 
 #define F2CYCLE_NSEC(f)			(1000000000 / (f))
 
+#define RZV2M_A_NSEC			730
+
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
@@ -51,11 +54,35 @@ struct rzg2l_wdt_priv {
 	struct reset_control *rstc;
 	unsigned long osc_clk_rate;
 	unsigned long delay;
+	unsigned long minimum_assertion_period;
 	struct clk *pclk;
 	struct clk *osc_clk;
 	enum rz_wdt_type devtype;
 };
 
+static int rzg2l_wdt_reset(struct rzg2l_wdt_priv *priv)
+{
+	int err, status;
+
+	if (priv->devtype == WDT_RZV2M) {
+		/* WDT needs TYPE-B reset control */
+		err = reset_control_assert(priv->rstc);
+		if (err)
+			return err;
+		ndelay(priv->minimum_assertion_period);
+		err = reset_control_deassert(priv->rstc);
+		if (err)
+			return err;
+		err = read_poll_timeout(reset_control_status, status,
+					status != 1, 0, 1000, false,
+					priv->rstc);
+	} else {
+		err = reset_control_reset(priv->rstc);
+	}
+
+	return err;
+}
+
 static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv)
 {
 	/* delay timer when change the setting register */
@@ -115,7 +142,7 @@ static int rzg2l_wdt_stop(struct watchdog_device *wdev)
 {
 	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
 
-	reset_control_reset(priv->rstc);
+	rzg2l_wdt_reset(priv);
 	pm_runtime_put(wdev->parent);
 
 	return 0;
@@ -154,6 +181,7 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
 		rzg2l_wdt_write(priv, PEEN_FORCE, PEEN);
 	} else {
 		/* RZ/V2M doesn't have parity error registers */
+		rzg2l_wdt_reset(priv);
 
 		wdev->timeout = 0;
 
@@ -251,6 +279,13 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
 
 	priv->devtype = (uintptr_t)of_device_get_match_data(dev);
 
+	if (priv->devtype == WDT_RZV2M) {
+		priv->minimum_assertion_period = RZV2M_A_NSEC +
+			3 * F2CYCLE_NSEC(pclk_rate) + 5 *
+			max(F2CYCLE_NSEC(priv->osc_clk_rate),
+			    F2CYCLE_NSEC(pclk_rate));
+	}
+
 	pm_runtime_enable(&pdev->dev);
 
 	priv->wdev.info = &rzg2l_wdt_ident;