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Message-ID: <e53c8e09-2ea6-4ce7-a5fa-811c7b3dd838@roeck-us.net>
Date: Tue, 30 May 2023 05:14:31 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Srinivas Neeli <srinivas.neeli@....com>
Cc: shubhrajyoti.datta@....com, michal.simek@....com,
srinivas.goud@....com, wim@...ux-watchdog.org, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org, linux-watchdog@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, git@....com, git@...inx.com,
neelisrinivas18@...il.com
Subject: Re: [PATCH V4 3/4] watchdog: xilinx_wwdt: Add Versal window watchdog
support
On Thu, Apr 20, 2023 at 04:12:30PM +0530, Srinivas Neeli wrote:
> Versal watchdog driver uses window watchdog mode. Window watchdog
> timer(WWDT) contains closed(first) and open(second) window with
> 32 bit width. Write to the watchdog timer within predefined window
> periods of time. This means a period that is not too soon and a
> period that is not too late. The WWDT has to be restarted within
> the open window time. If software tries to restart WWDT outside of
> the open window time period, it generates a reset.
>
> Signed-off-by: Srinivas Neeli <srinivas.neeli@....com>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> Changes in V4:
> -Maximum timeout value calculated at 100Mhz source clock. This value
> vary depending on the source clock to IP.
> -Removed module parameters prefix("x").
> -Moved closed window percent check to the probe fucntion and updated
> dependent code.
> Changes in V3:
> -Removed "xlnx,close_percent" support from dtb.
> -Added "xlnx,close_percent" property as module paratmeter.
> -Updated code with devm_clk_get_enabled().
> Changes in V2:
> - Takes "xlnx,close-percent" property from device tree parameter.
> - Removed clk_disable() function.
> - Removed module parameter permisions and using readomly.
> - Added check for close_percent( 0 < close_perecent < 100).
> - Updated other minor comments.
> ---
> drivers/watchdog/Kconfig | 18 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/xilinx_wwdt.c | 201 +++++++++++++++++++++++++++++++++
> 3 files changed, 220 insertions(+)
> create mode 100644 drivers/watchdog/xilinx_wwdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f0872970daf9..ec4b522ae29e 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -304,6 +304,24 @@ config XILINX_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called of_xilinx_wdt.
>
> +config XILINX_WINDOW_WATCHDOG
> + tristate "Xilinx window watchdog timer"
> + depends on HAS_IOMEM
> + depends on ARM64
> + select WATCHDOG_CORE
> + help
> + Window watchdog driver for the versal_wwdt IP core.
> + Window watchdog timer(WWDT) contains closed(first) and
> + open(second) window with 32 bit width. Write to the watchdog
> + timer within predefined window periods of time. This means
> + a period that is not too soon and a period that is not too
> + late. The WWDT has to be restarted within the open window time.
> + If software tries to restart WWDT outside of the open window
> + time period, it generates a reset.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called xilinx_wwdt.
> +
> config ZIIRAVE_WATCHDOG
> tristate "Zodiac RAVE Watchdog Timer"
> depends on I2C
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 9cbf6580f16c..6cb5f1dfb492 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -157,6 +157,7 @@ obj-$(CONFIG_M54xx_WATCHDOG) += m54xx_wdt.o
>
> # MicroBlaze Architecture
> obj-$(CONFIG_XILINX_WATCHDOG) += of_xilinx_wdt.o
> +obj-$(CONFIG_XILINX_WINDOW_WATCHDOG) += xilinx_wwdt.o
>
> # MIPS Architecture
> obj-$(CONFIG_ATH79_WDT) += ath79_wdt.o
> diff --git a/drivers/watchdog/xilinx_wwdt.c b/drivers/watchdog/xilinx_wwdt.c
> new file mode 100644
> index 000000000000..2585038d5575
> --- /dev/null
> +++ b/drivers/watchdog/xilinx_wwdt.c
> @@ -0,0 +1,201 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Window watchdog device driver for Xilinx Versal WWDT
> + *
> + * Copyright (C) 2022 - 2023, Advanced Micro Devices, Inc.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/of_address.h>
> +#include <linux/watchdog.h>
> +
> +/* Max timeout is calculated at 100MHz source clock */
> +#define XWWDT_DEFAULT_TIMEOUT 42
> +#define XWWDT_MIN_TIMEOUT 1
> +
> +/* Register offsets for the WWDT device */
> +#define XWWDT_MWR_OFFSET 0x00
> +#define XWWDT_ESR_OFFSET 0x04
> +#define XWWDT_FCR_OFFSET 0x08
> +#define XWWDT_FWR_OFFSET 0x0c
> +#define XWWDT_SWR_OFFSET 0x10
> +
> +/* Master Write Control Register Masks */
> +#define XWWDT_MWR_MASK BIT(0)
> +
> +/* Enable and Status Register Masks */
> +#define XWWDT_ESR_WINT_MASK BIT(16)
> +#define XWWDT_ESR_WSW_MASK BIT(8)
> +#define XWWDT_ESR_WEN_MASK BIT(0)
> +
> +#define XWWDT_CLOSE_WINDOW_PERCENT 50
> +
> +static int wwdt_timeout;
> +static int closed_window_percent;
> +
> +module_param(wwdt_timeout, int, 0);
> +MODULE_PARM_DESC(wwdt_timeout,
> + "Watchdog time in seconds. (default="
> + __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")");
> +module_param(closed_window_percent, int, 0);
> +MODULE_PARM_DESC(closed_window_percent,
> + "Watchdog closed window percentage. (default="
> + __MODULE_STRING(XWWDT_CLOSE_WINDOW_PERCENT) ")");
> +/**
> + * struct xwwdt_device - Watchdog device structure
> + * @base: base io address of WDT device
> + * @spinlock: spinlock for IO register access
> + * @xilinx_wwdt_wdd: watchdog device structure
> + * @freq: source clock frequency of WWDT
> + * @close_percent: Closed window percent
> + */
> +struct xwwdt_device {
> + void __iomem *base;
> + spinlock_t spinlock; /* spinlock for register handling */
> + struct watchdog_device xilinx_wwdt_wdd;
> + unsigned long freq;
> + u32 close_percent;
> +};
> +
> +static int xilinx_wwdt_start(struct watchdog_device *wdd)
> +{
> + struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
> + struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
> + u64 time_out, closed_timeout, open_timeout;
> + u32 control_status_reg;
> +
> + /* Calculate timeout count */
> + time_out = xdev->freq * wdd->timeout;
> + closed_timeout = (time_out * xdev->close_percent) / 100;
> + open_timeout = time_out - closed_timeout;
> + wdd->min_hw_heartbeat_ms = xdev->close_percent * 10 * wdd->timeout;
> +
> + spin_lock(&xdev->spinlock);
> +
> + iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
> + iowrite32(~(u32)XWWDT_ESR_WEN_MASK, xdev->base + XWWDT_ESR_OFFSET);
> + iowrite32((u32)closed_timeout, xdev->base + XWWDT_FWR_OFFSET);
> + iowrite32((u32)open_timeout, xdev->base + XWWDT_SWR_OFFSET);
> +
> + /* Enable the window watchdog timer */
> + control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
> + control_status_reg |= XWWDT_ESR_WEN_MASK;
> + iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
> +
> + spin_unlock(&xdev->spinlock);
> +
> + dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n");
> +
> + return 0;
> +}
> +
> +static int xilinx_wwdt_keepalive(struct watchdog_device *wdd)
> +{
> + struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
> + u32 control_status_reg;
> +
> + spin_lock(&xdev->spinlock);
> +
> + /* Enable write access control bit for the window watchdog */
> + iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
> +
> + /* Trigger restart kick to watchdog */
> + control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
> + control_status_reg |= XWWDT_ESR_WSW_MASK;
> + iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
> +
> + spin_unlock(&xdev->spinlock);
> +
> + return 0;
> +}
> +
> +static const struct watchdog_info xilinx_wwdt_ident = {
> + .options = WDIOF_KEEPALIVEPING |
> + WDIOF_SETTIMEOUT,
> + .firmware_version = 1,
> + .identity = "xlnx_window watchdog",
> +};
> +
> +static const struct watchdog_ops xilinx_wwdt_ops = {
> + .owner = THIS_MODULE,
> + .start = xilinx_wwdt_start,
> + .ping = xilinx_wwdt_keepalive,
> +};
> +
> +static int xwwdt_probe(struct platform_device *pdev)
> +{
> + struct watchdog_device *xilinx_wwdt_wdd;
> + struct device *dev = &pdev->dev;
> + struct xwwdt_device *xdev;
> + struct clk *clk;
> + int ret;
> +
> + xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
> + if (!xdev)
> + return -ENOMEM;
> +
> + xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
> + xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
> + xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
> + xilinx_wwdt_wdd->parent = dev;
> +
> + xdev->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(xdev->base))
> + return PTR_ERR(xdev->base);
> +
> + clk = devm_clk_get_enabled(dev, NULL);
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + xdev->freq = clk_get_rate(clk);
> + if (!xdev->freq)
> + return -EINVAL;
> +
> + xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
> + xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
> + xilinx_wwdt_wdd->max_hw_heartbeat_ms = 1000 * xilinx_wwdt_wdd->timeout;
> +
> + if (closed_window_percent == 0 || closed_window_percent >= 100)
> + xdev->close_percent = XWWDT_CLOSE_WINDOW_PERCENT;
> + else
> + xdev->close_percent = closed_window_percent;
> +
> + watchdog_init_timeout(xilinx_wwdt_wdd, wwdt_timeout, &pdev->dev);
> + spin_lock_init(&xdev->spinlock);
> + watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
> + watchdog_set_nowayout(xilinx_wwdt_wdd, 1);
> +
> + ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
> + if (ret)
> + return ret;
> +
> + dev_info(dev, "Xilinx window watchdog Timer with timeout %ds\n",
> + xilinx_wwdt_wdd->timeout);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id xwwdt_of_match[] = {
> + { .compatible = "xlnx,versal-wwdt", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, xwwdt_of_match);
> +
> +static struct platform_driver xwwdt_driver = {
> + .probe = xwwdt_probe,
> + .driver = {
> + .name = "Xilinx window watchdog",
> + .of_match_table = xwwdt_of_match,
> + },
> +};
> +
> +module_platform_driver(xwwdt_driver);
> +
> +MODULE_AUTHOR("Neeli Srinivas <srinivas.neeli@....com>");
> +MODULE_DESCRIPTION("Xilinx window watchdog driver");
> +MODULE_LICENSE("GPL");
> --
> 2.25.1
>
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