realtek: Backport Realtek Otto WDT driver

Add patch submitted upstream to linux-watchdog and replace the MIPS
architecture symbols. Requires one extra patch for the DIV_ROUND_*
macros, which have moved to a different header since 5.10.

Signed-off-by: Sander Vanheule <sander@svanheule.net>
Tested-by: Stijn Segers <foss@volatilesystems.org>
Tested-by: Paul Fertser <fercerpav@gmail.com>
Tested-by: Stijn Tintel <stijn@linux-ipv6.be>

3 files changed, 486 insertions, 0 deletions

diff --git a/target/linux/realtek/patches-5.10/100-watchdog-add-realtek-otto-watchdog-timer.patch b/target/linux/realtek/patches-5.10/100-watchdog-add-realtek-otto-watchdog-timer.patch
new file mode 100644
index 0000000000..5aa988dc55
--- /dev/null
+++ b/target/linux/realtek/patches-5.10/100-watchdog-add-realtek-otto-watchdog-timer.patch
@@ -0,0 +1,456 @@
+From 2dbf0c6e0eebf523008c15794434d2d1a9b1260e Mon Sep 17 00:00:00 2001
+Message-Id: <2dbf0c6e0eebf523008c15794434d2d1a9b1260e.1636018117.git.sander@svanheule.net>
+In-Reply-To: <cover.1636018117.git.sander@svanheule.net>
+References: <cover.1636018117.git.sander@svanheule.net>
+From: Sander Vanheule <sander@svanheule.net>
+Date: Sun, 3 Oct 2021 09:25:27 +0200
+Subject: [PATCH v3 2/2] watchdog: Add Realtek Otto watchdog timer
+
+Realtek MIPS SoCs (platform name Otto) have a watchdog timer with
+pretimeout notifitication support. The WDT can (partially) hard reset,
+or soft reset the SoC.
+
+This driver implements all features as described in the devicetree
+binding, except the phase2 interrupt, and also functions as a restart
+handler. The cpu reset mode is considered to be a "warm" restart, since
+this mode does not reset all peripherals. Being an embedded system
+though, the "cpu" and "software" modes will still cause the bootloader
+to run on restart.
+
+It is not known how a forced system reset can be disabled on the
+supported platforms. This means that the phase2 interrupt will only fire
+at the same time as reset, so implementing phase2 is of little use.
+
+Signed-off-by: Sander Vanheule <sander@svanheule.net>
+---
+ MAINTAINERS                         |   7 +
+ drivers/watchdog/Kconfig            |  13 +
+ drivers/watchdog/Makefile           |   1 +
+ drivers/watchdog/realtek_otto_wdt.c | 361 ++++++++++++++++++++++++++++
+ 4 files changed, 382 insertions(+)
+ create mode 100644 drivers/watchdog/realtek_otto_wdt.c
+
+diff --git a/MAINTAINERS b/MAINTAINERS
+index 2c9070aeba2a..54c8f788d3e5 100644
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -15991,6 +15991,13 @@ S:	Maintained
+ F:	include/sound/rt*.h
+ F:	sound/soc/codecs/rt*
+ 
++REALTEK OTTO WATCHDOG
++M:	Sander Vanheule <sander@svanheule.net>
++L:	linux-watchdog@vger.kernel.org
++S:	Maintained
++F:	Documentation/devicetree/bindings/watchdog/realtek,otto-wdt.yaml
++F:	driver/watchdog/realtek_otto_wdt.c
++
+ REALTEK RTL83xx SMI DSA ROUTER CHIPS
+ M:	Linus Walleij <linus.walleij@linaro.org>
+ S:	Maintained
+diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
+index bf59faeb3de1..d308e13a9aa1 100644
+--- a/drivers/watchdog/Kconfig
++++ b/drivers/watchdog/Kconfig
+@@ -954,6 +954,19 @@ config RTD119X_WATCHDOG
+ 	  Say Y here to include support for the watchdog timer in
+ 	  Realtek RTD1295 SoCs.
+ 
++config REALTEK_OTTO_WDT
++	tristate "Realtek Otto MIPS watchdog support"
++	depends on MACH_REALTEK_RTL || COMPILE_TEST
++	depends on COMMON_CLK
++	select WATCHDOG_CORE
++	default MACH_REALTEK_RTL
++	help
++	  Say Y here to include support for the watchdog timer on Realtek
++	  RTL838x, RTL839x, RTL930x SoCs. This watchdog has pretimeout
++	  notifications and system reset on timeout.
++
++	  When built as a module this will be called realtek_otto_wdt.
++
+ config SPRD_WATCHDOG
+ 	tristate "Spreadtrum watchdog support"
+ 	depends on ARCH_SPRD || COMPILE_TEST
+diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
+index 1bd2d6f37c53..a8dccf819163 100644
+--- a/drivers/watchdog/Makefile
++++ b/drivers/watchdog/Makefile
+@@ -171,6 +171,7 @@ obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o
+ obj-$(CONFIG_MT7621_WDT) += mt7621_wdt.o
+ obj-$(CONFIG_PIC32_WDT) += pic32-wdt.o
+ obj-$(CONFIG_PIC32_DMT) += pic32-dmt.o
++obj-$(CONFIG_REALTEK_OTTO_WDT) += realtek_otto_wdt.o
+ 
+ # PARISC Architecture
+ 
+diff --git a/drivers/watchdog/realtek_otto_wdt.c b/drivers/watchdog/realtek_otto_wdt.c
+new file mode 100644
+index 000000000000..48bc8dfefc25
+--- /dev/null
++++ b/drivers/watchdog/realtek_otto_wdt.c
+@@ -0,0 +1,361 @@
++// SPDX-License-Identifier: GPL-2.0-only
++
++/*
++ * Realtek Otto MIPS platform watchdog
++ *
++ * Watchdog timer that will reset the system after timeout, using the selected
++ * reset mode.
++ *
++ * Counter scaling and timeouts:
++ * - Base prescale of (2 << 25), providing tick duration T_0: 168ms @ 200MHz
++ * - PRESCALE: logarithmic prescaler adding a factor of {1, 2, 4, 8}
++ * - Phase 1: Times out after (PHASE1 + 1) × PRESCALE × T_0
++ *   Generates an interrupt, WDT cannot be stopped after phase 1
++ * - Phase 2: starts after phase 1, times out after (PHASE2 + 1) × PRESCALE × T_0
++ *   Resets the system according to RST_MODE
++ */
++
++#include <linux/bits.h>
++#include <linux/bitfield.h>
++#include <linux/clk.h>
++#include <linux/delay.h>
++#include <linux/interrupt.h>
++#include <linux/io.h>
++#include <linux/math.h>
++#include <linux/minmax.h>
++#include <linux/module.h>
++#include <linux/mod_devicetable.h>
++#include <linux/platform_device.h>
++#include <linux/property.h>
++#include <linux/reboot.h>
++#include <linux/watchdog.h>
++
++#define OTTO_WDT_REG_CNTR		0x0
++#define OTTO_WDT_CNTR_PING		BIT(31)
++
++#define OTTO_WDT_REG_INTR		0x4
++#define OTTO_WDT_INTR_PHASE_1		BIT(31)
++#define OTTO_WDT_INTR_PHASE_2		BIT(30)
++
++#define OTTO_WDT_REG_CTRL		0x8
++#define OTTO_WDT_CTRL_ENABLE		BIT(31)
++#define OTTO_WDT_CTRL_PRESCALE		GENMASK(30, 29)
++#define OTTO_WDT_CTRL_PHASE1		GENMASK(26, 22)
++#define OTTO_WDT_CTRL_PHASE2		GENMASK(19, 15)
++#define OTTO_WDT_CTRL_RST_MODE		GENMASK(1, 0)
++#define OTTO_WDT_MODE_SOC		0
++#define OTTO_WDT_MODE_CPU		1
++#define OTTO_WDT_MODE_SOFTWARE		2
++#define OTTO_WDT_CTRL_DEFAULT		OTTO_WDT_MODE_CPU
++
++#define OTTO_WDT_PRESCALE_MAX		3
++
++/*
++ * One higher than the max values contained in PHASE{1,2}, since a value of 0
++ * corresponds to one tick.
++ */
++#define OTTO_WDT_PHASE_TICKS_MAX	32
++
++/*
++ * The maximum reset delay is actually 2×32 ticks, but that would require large
++ * pretimeout values for timeouts longer than 32 ticks. Limit the maximum timeout
++ * to 32 + 1 to ensure small pretimeout values can be configured as expected.
++ */
++#define OTTO_WDT_TIMEOUT_TICKS_MAX	(OTTO_WDT_PHASE_TICKS_MAX + 1)
++
++struct otto_wdt_ctrl {
++	struct watchdog_device wdev;
++	struct device *dev;
++	void __iomem *base;
++	struct clk *clk;
++	int irq_phase1;
++};
++
++static int otto_wdt_start(struct watchdog_device *wdev)
++{
++	struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev);
++	u32 v;
++
++	v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL);
++	v |= OTTO_WDT_CTRL_ENABLE;
++	iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL);
++
++	return 0;
++}
++
++static int otto_wdt_stop(struct watchdog_device *wdev)
++{
++	struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev);
++	u32 v;
++
++	v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL);
++	v &= ~OTTO_WDT_CTRL_ENABLE;
++	iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL);
++
++	return 0;
++}
++
++static int otto_wdt_ping(struct watchdog_device *wdev)
++{
++	struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev);
++
++	iowrite32(OTTO_WDT_CNTR_PING, ctrl->base + OTTO_WDT_REG_CNTR);
++
++	return 0;
++}
++
++static int otto_wdt_tick_ms(struct otto_wdt_ctrl *ctrl, int prescale)
++{
++	unsigned int rate_khz = clk_get_rate(ctrl->clk) / 1000;
++
++	if (!rate_khz)
++		return 0;
++
++	return DIV_ROUND_CLOSEST(1 << (25 + prescale), rate_khz);
++}
++
++/*
++ * The timer asserts the PHASE1/PHASE2 IRQs when the number of ticks exceeds
++ * the value stored in those fields. This means each phase will run for at least
++ * one tick, so small values need to be clamped to correctly reflect the timeout.
++ */
++static inline unsigned int div_round_ticks(unsigned int val, unsigned int tick_duration,
++		unsigned int min_ticks)
++{
++	return max(min_ticks, DIV_ROUND_UP(val, tick_duration));
++}
++
++static int otto_wdt_determine_timeouts(struct watchdog_device *wdev, unsigned int timeout,
++		unsigned int pretimeout)
++{
++	struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev);
++	unsigned int pretimeout_ms = pretimeout * 1000;
++	unsigned int timeout_ms = timeout * 1000;
++	unsigned int prescale_next = 0;
++	unsigned int phase1_ticks;
++	unsigned int phase2_ticks;
++	unsigned int total_ticks;
++	unsigned int prescale;
++	unsigned int tick_ms;
++	u32 v;
++
++	do {
++		prescale = prescale_next;
++		if (prescale > OTTO_WDT_PRESCALE_MAX)
++			return -EINVAL;
++
++		tick_ms = otto_wdt_tick_ms(ctrl, prescale);
++		total_ticks = div_round_ticks(timeout_ms, tick_ms, 2);
++		phase1_ticks = div_round_ticks(timeout_ms - pretimeout_ms, tick_ms, 1);
++		phase2_ticks = total_ticks - phase1_ticks;
++
++		prescale_next++;
++	} while (phase1_ticks > OTTO_WDT_PHASE_TICKS_MAX
++		|| phase2_ticks > OTTO_WDT_PHASE_TICKS_MAX);
++
++	v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL);
++
++	v &= ~(OTTO_WDT_CTRL_PRESCALE | OTTO_WDT_CTRL_PHASE1 | OTTO_WDT_CTRL_PHASE2);
++	v |= FIELD_PREP(OTTO_WDT_CTRL_PHASE1, phase1_ticks - 1);
++	v |= FIELD_PREP(OTTO_WDT_CTRL_PHASE2, phase2_ticks - 1);
++	v |= FIELD_PREP(OTTO_WDT_CTRL_PRESCALE, prescale);
++
++	iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL);
++
++	timeout_ms = total_ticks * tick_ms;
++	ctrl->wdev.timeout = timeout_ms / 1000;
++
++	pretimeout_ms = phase2_ticks * tick_ms;
++	ctrl->wdev.pretimeout = pretimeout_ms / 1000;
++
++	return 0;
++}
++
++static int otto_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
++{
++	return otto_wdt_determine_timeouts(wdev, val, min(wdev->pretimeout, val - 1));
++}
++
++static int otto_wdt_set_pretimeout(struct watchdog_device *wdev, unsigned int val)
++{
++	return otto_wdt_determine_timeouts(wdev, wdev->timeout, val);
++}
++
++static int otto_wdt_restart(struct watchdog_device *wdev, unsigned long reboot_mode,
++		void *data)
++{
++	struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev);
++	u32 reset_mode;
++	u32 v;
++
++	disable_irq(ctrl->irq_phase1);
++
++	switch (reboot_mode) {
++	case REBOOT_SOFT:
++		reset_mode = OTTO_WDT_MODE_SOFTWARE;
++		break;
++	case REBOOT_WARM:
++		reset_mode = OTTO_WDT_MODE_CPU;
++		break;
++	default:
++		reset_mode = OTTO_WDT_MODE_SOC;
++		break;
++	}
++
++	/* Configure for shortest timeout and wait for reset to occur */
++	v = FIELD_PREP(OTTO_WDT_CTRL_RST_MODE, reset_mode) | OTTO_WDT_CTRL_ENABLE;
++	iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL);
++
++	mdelay(3 * otto_wdt_tick_ms(ctrl, 0));
++
++	return 0;
++}
++
++static irqreturn_t otto_wdt_phase1_isr(int irq, void *dev_id)
++{
++	struct otto_wdt_ctrl *ctrl = dev_id;
++
++	iowrite32(OTTO_WDT_INTR_PHASE_1, ctrl->base + OTTO_WDT_REG_INTR);
++	dev_crit(ctrl->dev, "phase 1 timeout\n");
++	watchdog_notify_pretimeout(&ctrl->wdev);
++
++	return IRQ_HANDLED;
++}
++
++static const struct watchdog_ops otto_wdt_ops = {
++	.owner = THIS_MODULE,
++	.start = otto_wdt_start,
++	.stop = otto_wdt_stop,
++	.ping = otto_wdt_ping,
++	.set_timeout = otto_wdt_set_timeout,
++	.set_pretimeout = otto_wdt_set_pretimeout,
++	.restart = otto_wdt_restart,
++};
++
++static const struct watchdog_info otto_wdt_info = {
++	.identity = "Realtek Otto watchdog timer",
++	.options = WDIOF_KEEPALIVEPING |
++		WDIOF_MAGICCLOSE |
++		WDIOF_SETTIMEOUT |
++		WDIOF_PRETIMEOUT,
++};
++
++static int otto_wdt_probe_reset_mode(struct otto_wdt_ctrl *ctrl)
++{
++	static const char *mode_property = "realtek,reset-mode";
++	const struct fwnode_handle *node = ctrl->dev->fwnode;
++	int mode_count;
++	u32 mode;
++	u32 v;
++
++	if (!node)
++		return -ENXIO;
++
++	mode_count = fwnode_property_string_array_count(node, mode_property);
++	if (mode_count < 0)
++		return mode_count;
++	else if (mode_count == 0)
++		return 0;
++	else if (mode_count != 1)
++		return -EINVAL;
++
++	if (fwnode_property_match_string(node, mode_property, "soc") == 0)
++		mode = OTTO_WDT_MODE_SOC;
++	else if (fwnode_property_match_string(node, mode_property, "cpu") == 0)
++		mode = OTTO_WDT_MODE_CPU;
++	else if (fwnode_property_match_string(node, mode_property, "software") == 0)
++		mode = OTTO_WDT_MODE_SOFTWARE;
++	else
++		return -EINVAL;
++
++	v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL);
++	v &= ~OTTO_WDT_CTRL_RST_MODE;
++	v |= FIELD_PREP(OTTO_WDT_CTRL_RST_MODE, mode);
++	iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL);
++
++	return 0;
++}
++
++static int otto_wdt_probe(struct platform_device *pdev)
++{
++	struct device *dev = &pdev->dev;
++	struct otto_wdt_ctrl *ctrl;
++	unsigned int max_tick_ms;
++	int ret;
++
++	ctrl = devm_kzalloc(dev, sizeof(*ctrl), GFP_KERNEL);
++	if (!ctrl)
++		return -ENOMEM;
++
++	ctrl->dev = dev;
++	ctrl->base = devm_platform_ioremap_resource(pdev, 0);
++	if (IS_ERR(ctrl->base))
++		return PTR_ERR(ctrl->base);
++
++	/* Clear any old interrupts and reset initial state */
++	iowrite32(OTTO_WDT_INTR_PHASE_1 | OTTO_WDT_INTR_PHASE_2,
++			ctrl->base + OTTO_WDT_REG_INTR);
++	iowrite32(OTTO_WDT_CTRL_DEFAULT, ctrl->base + OTTO_WDT_REG_CTRL);
++
++	ctrl->clk = devm_clk_get(dev, NULL);
++	if (IS_ERR(ctrl->clk))
++		return dev_err_probe(dev, PTR_ERR(ctrl->clk), "Failed to get clock\n");
++
++	ctrl->irq_phase1 = platform_get_irq_byname(pdev, "phase1");
++	if (ctrl->irq_phase1 < 0)
++		return dev_err_probe(dev, ctrl->irq_phase1, "phase1 IRQ not found\n");
++
++	ret = devm_request_irq(dev, ctrl->irq_phase1, otto_wdt_phase1_isr, 0,
++			"realtek-otto-wdt", ctrl);
++	if (ret)
++		return dev_err_probe(dev, ret, "Failed to get IRQ for phase1\n");
++
++	ret = otto_wdt_probe_reset_mode(ctrl);
++	if (ret)
++		return dev_err_probe(dev, ret, "Invalid reset mode specified\n");
++
++	ctrl->wdev.parent = dev;
++	ctrl->wdev.info = &otto_wdt_info;
++	ctrl->wdev.ops = &otto_wdt_ops;
++
++	/*
++	 * Since pretimeout cannot be disabled, min. timeout is twice the
++	 * subsystem resolution. max. timeout is ca. 43s at a bus clock of 200MHz.
++	 */
++	ctrl->wdev.min_timeout = 2;
++	max_tick_ms = otto_wdt_tick_ms(ctrl, OTTO_WDT_PRESCALE_MAX);
++	ctrl->wdev.max_hw_heartbeat_ms = max_tick_ms * OTTO_WDT_TIMEOUT_TICKS_MAX;
++	ctrl->wdev.timeout = min(30U, ctrl->wdev.max_hw_heartbeat_ms / 1000);
++
++	watchdog_set_drvdata(&ctrl->wdev, ctrl);
++	watchdog_init_timeout(&ctrl->wdev, 0, dev);
++	watchdog_stop_on_reboot(&ctrl->wdev);
++	watchdog_set_restart_priority(&ctrl->wdev, 128);
++
++	ret = otto_wdt_determine_timeouts(&ctrl->wdev, ctrl->wdev.timeout, 1);
++	if (ret)
++		return dev_err_probe(dev, ret, "Failed to set timeout\n");
++
++	return devm_watchdog_register_device(dev, &ctrl->wdev);
++}
++
++static const struct of_device_id otto_wdt_ids[] = {
++	{ .compatible = "realtek,rtl8380-wdt" },
++	{ .compatible = "realtek,rtl8390-wdt" },
++	{ .compatible = "realtek,rtl9300-wdt" },
++	{ }
++};
++MODULE_DEVICE_TABLE(of, otto_wdt_ids);
++
++static struct platform_driver otto_wdt_driver = {
++	.probe = otto_wdt_probe,
++	.driver = {
++		.name = "realtek-otto-watchdog",
++		.of_match_table	= otto_wdt_ids,
++	},
++};
++module_platform_driver(otto_wdt_driver);
++
++MODULE_LICENSE("GPL v2");
++MODULE_AUTHOR("Sander Vanheule <sander@svanheule.net>");
++MODULE_DESCRIPTION("Realtek Otto watchdog timer driver");
+-- 
+2.31.1
+
diff --git a/target/linux/realtek/patches-5.10/307-wdt-update-dependency-for-realtek-otto-wdt.patch b/target/linux/realtek/patches-5.10/307-wdt-update-dependency-for-realtek-otto-wdt.patch
new file mode 100644
index 0000000000..32c3e2bb69
--- /dev/null
+++ b/target/linux/realtek/patches-5.10/307-wdt-update-dependency-for-realtek-otto-wdt.patch
@@ -0,0 +1,17 @@
+Index: linux-5.10.76/drivers/watchdog/Kconfig
+===================================================================
+--- linux-5.10.76.orig/drivers/watchdog/Kconfig
++++ linux-5.10.76/drivers/watchdog/Kconfig
+@@ -997,10 +997,10 @@ config RTD119X_WATCHDOG
+ 
+ config REALTEK_OTTO_WDT
+ 	tristate "Realtek Otto MIPS watchdog support"
+-	depends on MACH_REALTEK_RTL || COMPILE_TEST
++	depends on RTL838X
+ 	depends on COMMON_CLK
+ 	select WATCHDOG_CORE
+-	default MACH_REALTEK_RTL
++	default RTL838X
+ 	help
+ 	  Say Y here to include support for the watchdog timer on Realtek
+ 	  RTL838x, RTL839x, RTL930x SoCs. This watchdog has pretimeout
diff --git a/target/linux/realtek/patches-5.10/308-otto-wdt-fix-missing-math-header.patch b/target/linux/realtek/patches-5.10/308-otto-wdt-fix-missing-math-header.patch
new file mode 100644
index 0000000000..20f86ed7e2
--- /dev/null
+++ b/target/linux/realtek/patches-5.10/308-otto-wdt-fix-missing-math-header.patch
@@ -0,0 +1,13 @@
+Index: linux-5.10.72/drivers/watchdog/realtek_otto_wdt.c
+===================================================================
+--- linux-5.10.72.orig/drivers/watchdog/realtek_otto_wdt.c
++++ linux-5.10.72/drivers/watchdog/realtek_otto_wdt.c
+@@ -21,7 +21,7 @@
+ #include <linux/delay.h>
+ #include <linux/interrupt.h>
+ #include <linux/io.h>
+-#include <linux/math.h>
++#include <linux/kernel.h>
+ #include <linux/minmax.h>
+ #include <linux/module.h>
+ #include <linux/mod_devicetable.h>