drivers/watchdog/rti_wdt.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Watchdog driver for the K3 RTI module
  *
  * (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/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>

 #define DEFAULT_HEARTBEAT 60

 /* Max heartbeat is calculated at 32kHz source clock */
 #define MAX_HEARTBEAT	1000

 /* Timer register set definition */
 #define RTIDWDCTRL	0x90
 #define RTIDWDPRLD	0x94
 #define RTIWDSTATUS	0x98
 #define RTIWDKEY	0x9c
 #define RTIDWDCNTR	0xa0
 #define RTIWWDRXCTRL	0xa4
 #define RTIWWDSIZECTRL	0xa8

 #define RTIWWDRX_NMI	0xa

 #define RTIWWDSIZE_50P		0x50
 #define RTIWWDSIZE_25P		0x500
 #define RTIWWDSIZE_12P5		0x5000
 #define RTIWWDSIZE_6P25		0x50000
 #define RTIWWDSIZE_3P125	0x500000

 #define WDENABLE_KEY	0xa98559da

 #define WDKEY_SEQ0		0xe51a
 #define WDKEY_SEQ1		0xa35c

 #define WDT_PRELOAD_SHIFT	13

 #define WDT_PRELOAD_MAX		0xfff

 #define DWDST			BIT(1)

 static int heartbeat = DEFAULT_HEARTBEAT;

 /*
  * struct to hold data for each WDT device
  * @base - base io address of WD device
  * @freq - source clock frequency of WDT
  * @wdd  - hold watchdog device as is in WDT core
  */
 struct rti_wdt_device {
 	void __iomem		*base;
 	unsigned long		freq;
 	struct watchdog_device	wdd;
 };

 static int rti_wdt_start(struct watchdog_device *wdd)
 {
 	u32 timer_margin;
 	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);

 	/* set timeout period */
 	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);

 	/*
 	 * 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);

 	/* Open window size 50%; this is the largest window size available */
 	writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);

 	readl_relaxed(wdt->base + RTIWWDSIZECTRL);

 	/* enable watchdog */
 	writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
 	return 0;
 }

 static int rti_wdt_ping(struct watchdog_device *wdd)
 {
 	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);

 	/* put watchdog in service state */
 	writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
 	/* put watchdog in active state */
 	writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);

 	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_ms(struct watchdog_device *wdd)
 {
 	u64 timer_counter;
 	u32 val;
 	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);

 	/* if timeout has occurred then return 0 */
 	val = readl_relaxed(wdt->base + RTIWDSTATUS);
 	if (val & DWDST)
 		return 0;

 	timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);

 	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",
 };

 static const struct watchdog_ops rti_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= rti_wdt_start,
 	.ping		= rti_wdt_ping,
 	.get_timeleft	= rti_wdt_get_timeleft,
 };

 static int rti_wdt_probe(struct platform_device *pdev)
 {
 	int ret = 0;
 	struct device *dev = &pdev->dev;
 	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;

 	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(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) {
 		if (ret != -EPROBE_DEFER)
 			dev_err(&pdev->dev, "runtime pm failed\n");
 		return ret;
 	}

 	platform_set_drvdata(pdev, wdt);

 	wdd = &wdt->wdd;
 	wdd->info = &rti_wdt_info;
 	wdd->ops = &rti_wdt_ops;
 	wdd->min_timeout = 1;
 	wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
 		wdt->freq * 1000;
 	wdd->parent = dev;

 	watchdog_set_drvdata(wdd, wdt);
 	watchdog_set_nowayout(wdd, 1);
 	watchdog_set_restart_priority(wdd, 128);

 	wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	wdt->base = devm_ioremap_resource(dev, wdt_mem);
 	if (IS_ERR(wdt->base)) {
 		ret = PTR_ERR(wdt->base);
 		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;
 }

 static int rti_wdt_remove(struct platform_device *pdev)
 {
 	struct rti_wdt_device *wdt = platform_get_drvdata(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,j7-rti-wdt", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);

 static struct platform_driver rti_wdt_driver = {
 	.driver = {
 		.name = "rti-wdt",
 		.of_match_table = rti_wdt_of_match,
 	},
 	.probe = rti_wdt_probe,
 	.remove = rti_wdt_remove,
 };

 module_platform_driver(rti_wdt_driver);

 MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
 MODULE_DESCRIPTION("K3 RTI Watchdog Driver");

 module_param(heartbeat, int, 0);
 MODULE_PARM_DESC(heartbeat,
 		 "Watchdog heartbeat period in seconds from 1 to "
 		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
 		 __MODULE_STRING(DEFAULT_HEARTBEAT));

 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:rti-wdt");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Watchdog driver for the K3 RTI module
	*
	* (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/platform_device.h>
	#include <linux/pm_runtime.h>
	#include <linux/types.h>
	#include <linux/watchdog.h>

	#define DEFAULT_HEARTBEAT 60

	/* Max heartbeat is calculated at 32kHz source clock */
	#define MAX_HEARTBEAT 1000

	/* Timer register set definition */
	#define RTIDWDCTRL 0x90
	#define RTIDWDPRLD 0x94
	#define RTIWDSTATUS 0x98
	#define RTIWDKEY 0x9c
	#define RTIDWDCNTR 0xa0
	#define RTIWWDRXCTRL 0xa4
	#define RTIWWDSIZECTRL 0xa8

	#define RTIWWDRX_NMI 0xa

	#define RTIWWDSIZE_50P 0x50
	#define RTIWWDSIZE_25P 0x500
	#define RTIWWDSIZE_12P5 0x5000
	#define RTIWWDSIZE_6P25 0x50000
	#define RTIWWDSIZE_3P125 0x500000

	#define WDENABLE_KEY 0xa98559da

	#define WDKEY_SEQ0 0xe51a
	#define WDKEY_SEQ1 0xa35c

	#define WDT_PRELOAD_SHIFT 13

	#define WDT_PRELOAD_MAX 0xfff

	#define DWDST BIT(1)

	static int heartbeat = DEFAULT_HEARTBEAT;

	/*
	* struct to hold data for each WDT device
	* @base - base io address of WD device
	* @freq - source clock frequency of WDT
	* @wdd - hold watchdog device as is in WDT core
	*/
	struct rti_wdt_device {
	void __iomem *base;
	unsigned long freq;
	struct watchdog_device wdd;
	};

	static int rti_wdt_start(struct watchdog_device *wdd)
	{
	u32 timer_margin;
	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);

	/* set timeout period */
	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);

	/*
	* 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);

	/* Open window size 50%; this is the largest window size available */
	writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);

	readl_relaxed(wdt->base + RTIWWDSIZECTRL);

	/* enable watchdog */
	writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
	return 0;
	}

	static int rti_wdt_ping(struct watchdog_device *wdd)
	{
	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);

	/* put watchdog in service state */
	writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
	/* put watchdog in active state */
	writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);

	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_ms(struct watchdog_device *wdd)
	{
	u64 timer_counter;
	u32 val;
	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);

	/* if timeout has occurred then return 0 */
	val = readl_relaxed(wdt->base + RTIWDSTATUS);
	if (val & DWDST)
	return 0;

	timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);

	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",
	};

	static const struct watchdog_ops rti_wdt_ops = {
	.owner = THIS_MODULE,
	.start = rti_wdt_start,
	.ping = rti_wdt_ping,
	.get_timeleft = rti_wdt_get_timeleft,
	};

	static int rti_wdt_probe(struct platform_device *pdev)
	{
	int ret = 0;
	struct device *dev = &pdev->dev;
	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;

	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(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) {
	if (ret != -EPROBE_DEFER)
	dev_err(&pdev->dev, "runtime pm failed\n");
	return ret;
	}

	platform_set_drvdata(pdev, wdt);

	wdd = &wdt->wdd;
	wdd->info = &rti_wdt_info;
	wdd->ops = &rti_wdt_ops;
	wdd->min_timeout = 1;
	wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
	wdt->freq * 1000;
	wdd->parent = dev;

	watchdog_set_drvdata(wdd, wdt);
	watchdog_set_nowayout(wdd, 1);
	watchdog_set_restart_priority(wdd, 128);

	wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	wdt->base = devm_ioremap_resource(dev, wdt_mem);
	if (IS_ERR(wdt->base)) {
	ret = PTR_ERR(wdt->base);
	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;
	}

	static int rti_wdt_remove(struct platform_device *pdev)
	{
	struct rti_wdt_device *wdt = platform_get_drvdata(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,j7-rti-wdt", },
	{},
	};
	MODULE_DEVICE_TABLE(of, rti_wdt_of_match);

	static struct platform_driver rti_wdt_driver = {
	.driver = {
	.name = "rti-wdt",
	.of_match_table = rti_wdt_of_match,
	},
	.probe = rti_wdt_probe,
	.remove = rti_wdt_remove,
	};

	module_platform_driver(rti_wdt_driver);

	MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
	MODULE_DESCRIPTION("K3 RTI Watchdog Driver");

	module_param(heartbeat, int, 0);
	MODULE_PARM_DESC(heartbeat,
	"Watchdog heartbeat period in seconds from 1 to "
	__MODULE_STRING(MAX_HEARTBEAT) ", default "
	__MODULE_STRING(DEFAULT_HEARTBEAT));

	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:rti-wdt");