[PATCH v2 1/3] watchdog: Add support for K3 RTI watchdog

[Lokesh Vutla <lokeshvutla@ti.com>]

On 23/06/20 4:45 pm, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This is based on the Linux kernel driver for the RTI watchdog.
> 
> To actually reset the system on an AM65x, it requires firmware running
> on the R5 that accepts the NMI and issues the actual system reset via
> TISCI. Kind of an iTCO, except that this watchdog hardware has support
> for no-way-out, and only for that.
> 
> On the J721E, reset works without extra firmware help when routing the
> RTI interrupt via the ESM.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  drivers/watchdog/Kconfig   |   7 +++
>  drivers/watchdog/Makefile  |   1 +
>  drivers/watchdog/rti_wdt.c | 123 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 131 insertions(+)
>  create mode 100644 drivers/watchdog/rti_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index bf06180cdd..ee99bd2af1 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -155,6 +155,13 @@ config WDT_ORION
>  	  Select this to enable Orion watchdog timer, which can be found on some
>  	  Marvell Armada chips.
>  
> +config WDT_K3_RTI
> +	bool "Texas Instruments K3 RTI watchdog"
> +	depends on WDT && ARCH_K3
> +	help
> +	  Say Y here if you want to include support for the K3 watchdog
> +	  timer (RTI module) available in the K3 generation of processors.
> +
>  config WDT_SANDBOX
>  	bool "Enable Watchdog Timer support for Sandbox"
>  	depends on SANDBOX && WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 519bbd3a40..16bdbf4970 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -27,6 +27,7 @@ obj-$(CONFIG_WDT_MPC8xx) += mpc8xx_wdt.o
>  obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
>  obj-$(CONFIG_WDT_MTK) += mtk_wdt.o
>  obj-$(CONFIG_WDT_OMAP3) += omap_wdt.o
> +obj-$(CONFIG_WDT_K3_RTI) += rti_wdt.o
>  obj-$(CONFIG_WDT_SP805) += sp805_wdt.o
>  obj-$(CONFIG_WDT_STM32MP) += stm32mp_wdt.o
>  obj-$(CONFIG_WDT_TANGIER) += tangier_wdt.o
> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
> new file mode 100644
> index 0000000000..ebe29c7409
> --- /dev/null
> +++ b/drivers/watchdog/rti_wdt.c
> @@ -0,0 +1,123 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) Siemens AG, 2020
> + *
> + * Authors:
> + *   Jan Kiszka <jan.kiszka@siemens.com>
> + *
> + * Derived from linux/drivers/watchdog/rti_wdt.c
> + */
> +
> +#include <common.h>
> +#include <clk.h>
> +#include <dm.h>
> +#include <power-domain.h>
> +#include <wdt.h>
> +#include <asm/io.h>
> +
> +/* 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 WDENABLE_KEY		0xa98559da
> +
> +#define WDKEY_SEQ0		0xe51a
> +#define WDKEY_SEQ1		0xa35c
> +
> +#define WDT_PRELOAD_SHIFT	13
> +
> +#define WDT_PRELOAD_MAX		0xfff
> +
> +struct rti_wdt_priv {
> +	phys_addr_t regs;
> +	unsigned int clk_khz;
> +};
> +
> +static int rti_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
> +{
> +	struct rti_wdt_priv *priv = dev_get_priv(dev);
> +	u32 timer_margin;
> +	int ret;
> +
> +	if (readl(priv->regs + RTIDWDCTRL) == WDENABLE_KEY)
> +		return -EBUSY;
> +
> +	timer_margin = timeout_ms * priv->clk_khz / 1000;
> +	timer_margin >>= WDT_PRELOAD_SHIFT;
> +	if (timer_margin > WDT_PRELOAD_MAX)
> +		timer_margin = WDT_PRELOAD_MAX;
> +
> +	writel(timer_margin, priv->regs + RTIDWDPRLD);
> +	writel(RTIWWDRX_NMI, priv->regs + RTIWWDRXCTRL);
> +	writel(RTIWWDSIZE_50P, priv->regs + RTIWWDSIZECTRL);
> +
> +	readl(priv->regs + RTIWWDSIZECTRL);
> +
> +	writel(WDENABLE_KEY, priv->regs + RTIDWDCTRL);

What happens if the watchdog timer expires in U-Boot?

Is the watchdog started from U-Boot command line?

> +
> +	return 0;
> +}
> +
> +static int rti_wdt_reset(struct udevice *dev)
> +{
> +	struct rti_wdt_priv *priv = dev_get_priv(dev);
> +	u32 prld;
> +
> +	/* Make sure we do not reset too early */
> +	prld = readl(priv->regs + RTIDWDPRLD) << WDT_PRELOAD_SHIFT;
> +	if (readl(priv->regs + RTIDWDCNTR) >= prld / 2)
> +		return -EPERM;
> +
> +	writel(WDKEY_SEQ0, priv->regs + RTIWDKEY);
> +	writel(WDKEY_SEQ1, priv->regs + RTIWDKEY);
> +
> +	return 0;
> +}
> +
> +static int rti_wdt_probe(struct udevice *dev)
> +{
> +	struct rti_wdt_priv *priv = dev_get_priv(dev);
> +	struct clk clk;
> +	int ret;
> +
> +	priv->regs = devfdt_get_addr(dev);
> +	if (!priv->regs)
> +		return -EINVAL;
> +
> +	ret = clk_get_by_index(dev, 0, &clk);
> +	if (ret)
> +		return ret;
> +
> +	priv->clk_khz = clk_get_rate(&clk);
> +
> +	return 0;
> +}
> +
> +static const struct wdt_ops rti_wdt_ops = {
> +	.start = rti_wdt_start,
> +	.reset = rti_wdt_reset,
> +};
> +
> +static const struct udevice_id rti_wdt_ids[] = {
> +	{ .compatible = "ti,j7-rti-wdt" },

Is this compatible matching with Kernel's compatible?

Thanks and regards,
Lokesh