Re: [PATCH v4] wdt: nuvoton: Add support for Nuvoton

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 15 Mar 2022 10:14:16 +0800
Jim Liu <jim.t90615@gmail.com> wrote:

> Add watchdog controller driver for NPCM7xx/npcm8xx
> 
> Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
> Reviewed-by: Stefan Roese <sr@denx.de>
> 
> Changes for v4:
>    - add a bit of detail about the device in Kconfig
>    - lower-case hex change
>    - remove the  reset function delay.Actually when
>      setting writel NPCM_WTR the watchdog is resetting the BMC
> ---
>  drivers/watchdog/Kconfig    |   8 +++
>  drivers/watchdog/Makefile   |   1 +
>  drivers/watchdog/npcm_wdt.c | 117 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 126 insertions(+)
>  create mode 100644 drivers/watchdog/npcm_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index f90f0ca02b..d33882fb6a 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -196,6 +196,14 @@ config WDT_MTK
>  	  The watchdog timer is stopped when initialized.
>  	  It performs full SoC reset.
>  
> +config WDT_NPCM
> +	bool "Nuvoton watchdog timer support"
> +	depends on WDT && ARCH_NPCM
> +	help
> +	  This enables Nuvoton npcm7xx/npcm8xx watchdog timer driver,
> +	  The watchdog timer is stopped when initialized.
> +	  It performs full SoC reset.
> +
>  config WDT_OCTEONTX
>  	bool "OcteonTX core watchdog support"
>  	depends on WDT && (ARCH_OCTEONTX || ARCH_OCTEONTX2)
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index a35bd559f5..1089cd21f5 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -31,6 +31,7 @@ obj-$(CONFIG_WDT_MPC8xx) += mpc8xx_wdt.o
>  obj-$(CONFIG_WDT_MT7620) += mt7620_wdt.o
>  obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
>  obj-$(CONFIG_WDT_MTK) += mtk_wdt.o
> +obj-$(CONFIG_WDT_NPCM) += npcm_wdt.o
>  obj-$(CONFIG_WDT_OCTEONTX) += octeontx_wdt.o
>  obj-$(CONFIG_WDT_OMAP3) += omap_wdt.o
>  obj-$(CONFIG_WDT_SBSA) += sbsa_gwdt.o
> diff --git a/drivers/watchdog/npcm_wdt.c b/drivers/watchdog/npcm_wdt.c
> new file mode 100644
> index 0000000000..0aedb2fbe7
> --- /dev/null
> +++ b/drivers/watchdog/npcm_wdt.c
> @@ -0,0 +1,117 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2022 Nuvoton Technology, Inc
> + */
> +
> +#include <dm.h>
> +#include <errno.h>
> +#include <log.h>
> +#include <wdt.h>
> +#include <asm/io.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +
> +#define NPCM_WTCLK	(BIT(10) | BIT(11))	/* Clock divider */
> +#define NPCM_WTE	BIT(7)			/* Enable */
> +#define NPCM_WTIE	BIT(6)			/* Enable irq */
> +#define NPCM_WTIS	(BIT(4) | BIT(5))	/* Interval selection */
> +#define NPCM_WTIF	BIT(3)			/* Interrupt flag*/
> +#define NPCM_WTRF	BIT(2)			/* Reset flag */
> +#define NPCM_WTRE	BIT(1)			/* Reset enable */
> +#define NPCM_WTR	BIT(0)			/* Reset counter */
> +
> +struct npcm_wdt_priv {
> +	void __iomem *regs;
> +};
> +
> +static int npcm_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
> +{
> +	struct npcm_wdt_priv *priv = dev_get_priv(dev);
> +	u32 time_out, val;
> +
> +	time_out = (u32)(timeout_ms) / 1000;
> +	if (time_out < 2)
> +		val = 0x800;
> +	else if (time_out < 3)
> +		val = 0x420;
> +	else if (time_out < 6)
> +		val = 0x810;
> +	else if (time_out < 11)
> +		val = 0x430;
> +	else if (time_out < 22)
> +		val = 0x820;
> +	else if (time_out < 44)
> +		val = 0xc00;
> +	else if (time_out < 87)
> +		val = 0x830;
> +	else if (time_out < 173)
> +		val = 0xc10;
> +	else if (time_out < 688)
> +		val = 0xc20;
> +	else
> +		val = 0xc30;
> +
> +	val |= NPCM_WTRE | NPCM_WTE | NPCM_WTR | NPCM_WTIE;
> +	writel(val, priv->regs);
> +
> +	return 0;
> +}
> +
> +static int npcm_wdt_stop(struct udevice *dev)
> +{
> +	struct npcm_wdt_priv *priv = dev_get_priv(dev);
> +
> +	writel(0, priv->regs);
> +
> +	return 0;
> +}
> +
> +static int npcm_wdt_reset(struct udevice *dev)
> +{
> +	struct npcm_wdt_priv *priv = dev_get_priv(dev);
> +
> +	writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, priv->regs);
> +
> +	return 0;
> +}
> +
> +static int npcm_wdt_of_to_plat(struct udevice *dev)
> +{
> +	struct npcm_wdt_priv *priv = dev_get_priv(dev);
> +
> +	priv->regs = dev_read_addr_ptr(dev);
> +	if (!priv->regs)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static const struct wdt_ops npcm_wdt_ops = {
> +	.start = npcm_wdt_start,
> +	.reset = npcm_wdt_reset,
> +	.stop = npcm_wdt_stop,
> +};
> +
> +static const struct udevice_id npcm_wdt_ids[] = {
> +	{ .compatible = "nuvoton,npcm750-wdt" },
> +	{ .compatible = "nuvoton,npcm845-wdt" },

Do we really need a second compatible string listed here? From this
driver's perspective both seem to be compatible, are there other
features (not used by U-Boot) which differ?
From a quick search I couldn't find a binding or other information
about this new version of the watchdog, it's not even in the DT posted
before.

Cheers,
Andre


> +	{ }
> +};
> +
> +static int npcm_wdt_probe(struct udevice *dev)
> +{
> +	debug("%s() wdt%u\n", __func__, dev_seq(dev));
> +	npcm_wdt_stop(dev);
> +
> +	return 0;
> +}
> +
> +U_BOOT_DRIVER(npcm_wdt) = {
> +	.name = "npcm_wdt",
> +	.id = UCLASS_WDT,
> +	.of_match = npcm_wdt_ids,
> +	.probe = npcm_wdt_probe,
> +	.priv_auto = sizeof(struct npcm_wdt_priv),
> +	.of_to_plat = npcm_wdt_of_to_plat,
> +	.ops = &npcm_wdt_ops,
> +};