IOT2000_BuildRoot/board/PSG/iot2050/files/0025-watchdog-rti_wdt-Backport-mainline-driver.patch

From 4823856642a29f81c2310a05b4687588c62633fb Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Fri, 30 Jul 2021 13:53:20 +0200
Subject: [PATCH 25/26] watchdog: rti_wdt: Backport mainline driver

Corresponds to 8711071e9700b67045fe5518161d63f7a03e3c9e upstream.

This comes with a lot of improvements, specifically for picking up a
watchdog already started by the firmware.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 drivers/watchdog/rti_wdt.c | 194 ++++++++++++++++++++++++++++---------
 1 file changed, 146 insertions(+), 48 deletions(-)

diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index b0933b090f53..e3c90e617c7a 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -2,26 +2,27 @@
 /*
  * Watchdog driver for the K3 RTI module
  *
- * (c) Copyright 2019 Texas Instruments Inc.
+ * (c) Copyright 2019-2020 Texas Instruments Inc.
  * All rights reserved.
  */
 
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
-#include <linux/mod_devicetable.h>
-#include <linux/types.h>
-#include <linux/kernel.h>
-#include <linux/watchdog.h>
 #include <linux/platform_device.h>
-#include <linux/io.h>
-#include <linux/device.h>
-#include <linux/clk.h>
-#include <linux/err.h>
 #include <linux/pm_runtime.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
 
-#define MODULE_NAME "rti-wdt"
 #define DEFAULT_HEARTBEAT 60
-#define MAX_HEARTBEAT     1000
+
+/* Max heartbeat is calculated at 32kHz source clock */
+#define MAX_HEARTBEAT	1000
 
 /* Timer register set definition */
 #define RTIDWDCTRL	0x90
@@ -34,7 +35,11 @@
 
 #define RTIWWDRX_NMI	0xa
 
-#define RTIWWDSIZE_50P	0x50
+#define RTIWWDSIZE_50P		0x50
+#define RTIWWDSIZE_25P		0x500
+#define RTIWWDSIZE_12P5		0x5000
+#define RTIWWDSIZE_6P25		0x50000
+#define RTIWWDSIZE_3P125	0x500000
 
 #define WDENABLE_KEY	0xa98559da
 
@@ -47,42 +52,45 @@
 
 #define DWDST			BIT(1)
 
-static int heartbeat;
+static int heartbeat = DEFAULT_HEARTBEAT;
 
 /*
  * struct to hold data for each WDT device
  * @base - base io address of WD device
- * @clk - source clock of WDT
- * @wdd - hold watchdog device as is in WDT core
+ * @freq - source clock frequency of WDT
+ * @wdd  - hold watchdog device as is in WDT core
  */
 struct rti_wdt_device {
 	void __iomem		*base;
-	struct clk		*clk;
+	unsigned long		freq;
 	struct watchdog_device	wdd;
 };
 
 static int rti_wdt_start(struct watchdog_device *wdd)
 {
 	u32 timer_margin;
-	unsigned long freq;
 	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 
-	freq = clk_get_rate(wdt->clk);
-
 	/* set timeout period */
-	timer_margin = (u64)wdd->timeout * freq;
+	timer_margin = (u64)wdd->timeout * wdt->freq;
 	timer_margin >>= WDT_PRELOAD_SHIFT;
 	if (timer_margin > WDT_PRELOAD_MAX)
 		timer_margin = WDT_PRELOAD_MAX;
 	writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
 
-	/* Set min heartbeat to 1.1x window size */
-	wdd->min_hw_heartbeat_ms = 11 * wdd->timeout * 1000 / 20;
+	/*
+	 * RTI only supports a windowed mode, where the watchdog can only
+	 * be petted during the open window; not too early or not too late.
+	 * The HW configuration options only allow for the open window size
+	 * to be 50% or less than that; we obviouly want to configure the open
+	 * window as large as possible so we select the 50% option.
+	 */
+	wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
 
 	/* Generate NMI when wdt expires */
 	writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
 
-	/* Window size 50% */
+	/* Open window size 50%; this is the largest window size available */
 	writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
 
 	readl_relaxed(wdt->base + RTIWWDSIZECTRL);
@@ -101,16 +109,53 @@ static int rti_wdt_ping(struct watchdog_device *wdd)
 	/* put watchdog in active state */
 	writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
 
-	if (readl_relaxed(wdt->base + RTIWDSTATUS))
-		WARN_ON_ONCE(1);
+	return 0;
+}
+
+static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
+{
+	/*
+	 * RTI only supports a windowed mode, where the watchdog can only
+	 * be petted during the open window; not too early or not too late.
+	 * The HW configuration options only allow for the open window size
+	 * to be 50% or less than that.
+	 */
+	switch (wsize) {
+	case RTIWWDSIZE_50P:
+		/* 50% open window => 50% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 500 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_25P:
+		/* 25% open window => 75% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 750 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_12P5:
+		/* 12.5% open window => 87.5% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 875 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_6P25:
+		/* 6.5% open window => 93.5% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 935 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_3P125:
+		/* 3.125% open window => 96.9% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 969 * heartbeat;
+		break;
+
+	default:
+		return -EINVAL;
+	}
 
 	return 0;
 }
 
-static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
+static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
 {
 	u64 timer_counter;
-	unsigned long freq;
 	u32 val;
 	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 
@@ -119,17 +164,20 @@ static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
 	if (val & DWDST)
 		return 0;
 
-	freq = clk_get_rate(wdt->clk);
-	if (!freq)
-		return 0;
-
 	timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
 
-	do_div(timer_counter, freq);
+	timer_counter *= 1000;
+
+	do_div(timer_counter, wdt->freq);
 
 	return timer_counter;
 }
 
+static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	return rti_wdt_get_timeleft_ms(wdd) / 1000;
+}
+
 static const struct watchdog_info rti_wdt_info = {
 	.options = WDIOF_KEEPALIVEPING,
 	.identity = "K3 RTI Watchdog",
@@ -149,23 +197,43 @@ static int rti_wdt_probe(struct platform_device *pdev)
 	struct resource *wdt_mem;
 	struct watchdog_device *wdd;
 	struct rti_wdt_device *wdt;
+	struct clk *clk;
+	u32 last_ping = 0;
 
 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 	if (!wdt)
 		return -ENOMEM;
 
-	wdt->clk = devm_clk_get(dev, NULL);
-	if (IS_ERR(wdt->clk)) {
-		if (PTR_ERR(wdt->clk) != -EPROBE_DEFER)
+	clk = clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		if (PTR_ERR(clk) != -EPROBE_DEFER)
 			dev_err(dev, "failed to get clock\n");
-		return PTR_ERR(wdt->clk);
+		return PTR_ERR(clk);
+	}
+
+	wdt->freq = clk_get_rate(clk);
+
+	clk_put(clk);
+
+	if (!wdt->freq) {
+		dev_err(dev, "Failed to get fck rate.\n");
+		return -EINVAL;
 	}
 
+	/*
+	 * If watchdog is running at 32k clock, it is not accurate.
+	 * Adjust frequency down in this case so that we don't pet
+	 * the watchdog too often.
+	 */
+	if (wdt->freq < 32768)
+		wdt->freq = wdt->freq * 9 / 10;
+
 	pm_runtime_enable(dev);
 	ret = pm_runtime_get_sync(dev);
 	if (ret) {
+		pm_runtime_put_noidle(dev);
 		if (ret != -EPROBE_DEFER)
-			dev_err(&pdev->dev, "runtime pm failed\n");
+			dev_err(dev, "runtime pm failed\n");
 		return ret;
 	}
 
@@ -175,18 +243,10 @@ static int rti_wdt_probe(struct platform_device *pdev)
 	wdd->info = &rti_wdt_info;
 	wdd->ops = &rti_wdt_ops;
 	wdd->min_timeout = 1;
-	/* Set min heartbeat to 1.1x window size */
-	wdd->min_hw_heartbeat_ms = 11 * DEFAULT_HEARTBEAT * 1000 / 20;
-	wdd->max_hw_heartbeat_ms = MAX_HEARTBEAT * 1000;
-	wdd->timeout = DEFAULT_HEARTBEAT;
+	wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
+		wdt->freq * 1000;
 	wdd->parent = dev;
 
-	set_bit(WDOG_RESET_KEEPALIVE, &wdd->status);
-
-	watchdog_init_timeout(wdd, heartbeat, dev);
-
-	dev_info(dev, "heartbeat %d sec\n", wdd->timeout);
-
 	watchdog_set_drvdata(wdd, wdt);
 	watchdog_set_nowayout(wdd, 1);
 	watchdog_set_restart_priority(wdd, 128);
@@ -198,16 +258,53 @@ static int rti_wdt_probe(struct platform_device *pdev)
 		goto err_iomap;
 	}
 
+	if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
+		u32 time_left_ms;
+		u64 heartbeat_ms;
+		u32 wsize;
+
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+		time_left_ms = rti_wdt_get_timeleft_ms(wdd);
+		heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
+		heartbeat_ms <<= WDT_PRELOAD_SHIFT;
+		heartbeat_ms *= 1000;
+		do_div(heartbeat_ms, wdt->freq);
+		if (heartbeat_ms != heartbeat * 1000)
+			dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
+
+		heartbeat = heartbeat_ms;
+		heartbeat /= 1000;
+
+		wsize = readl(wdt->base + RTIWWDSIZECTRL);
+		ret = rti_wdt_setup_hw_hb(wdd, wsize);
+		if (ret) {
+			dev_err(dev, "bad window size.\n");
+			goto err_iomap;
+		}
+
+		last_ping = heartbeat_ms - time_left_ms;
+		if (time_left_ms > heartbeat_ms) {
+			dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
+			last_ping = 0;
+		}
+	}
+
+	watchdog_init_timeout(wdd, heartbeat, dev);
+
 	ret = watchdog_register_device(wdd);
 	if (ret) {
 		dev_err(dev, "cannot register watchdog device\n");
 		goto err_iomap;
 	}
 
+	if (last_ping)
+		watchdog_set_last_hw_keepalive(wdd, last_ping);
+
 	return 0;
 
 err_iomap:
 	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 
 	return ret;
 }
@@ -218,12 +315,13 @@ static int rti_wdt_remove(struct platform_device *pdev)
 
 	watchdog_unregister_device(&wdt->wdd);
 	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 
 	return 0;
 }
 
 static const struct of_device_id rti_wdt_of_match[] = {
-	{ .compatible = "ti,rti-wdt", },
+	{ .compatible = "ti,j7-rti-wdt", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
-- 
2.31.1