Re: [PATCH v7] wdt: nuvoton: Add support for Nuvoton

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

On Tue, 22 Mar 2022 17:19:53 +0800
Jim Liu <jim.t90615@gmail.com> wrote:

Hi,

> Add watchdog controller driver for NPCM7xx/npcm8xx

So this is now the same as v4, with both compatible strings listed.
Which *might* be right, but my question still stands:

Is the 845 watchdog compatible to the 740 version? Does the current
Linux driver work?

If yes (and your driver suggests so, because you treat the two
compatible strings the same), then you would not need to list both *in
the driver*, but just do so in the .dts file.

So the driver just matches "nuvoton,npcm750-wdt" (as does the Linux
driver), the nuvoton-common-npcm7xx.dtsi stays the same, but in the
npcm845.dtsi you write:
	watchdog: watchdog@xxx {
		compatible = "nuvoton,npcm845-wdt",
			     "nuvoton,npcm750-wdt";
		interrupts = ...
		...
	};

This way you don't need to change the (Linux) driver, and get away with
one compatible string, for both devices.

So can you please confirm that both are compatible. I couldn't find any
information on that.

Please just don't send another patch without answering the question ;-)

Cheers,
Andre

> Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
> Reviewed-by: Stefan Roese <sr@denx.de>
> Reviewed-by: Simon Glass <sjg@chromium.org>
> 
> Changes for v2:
>    - coding style cleanup
>    - change register type from struct
> Changes for v3:
>    - remove common.h
> 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
> changes for v5:
>    - modify compatible name to support all NPCM SOC
> changes for v6:
>    - followed linux kernel to modify compatible name
> change for v7:
>    - add second compatible name to driver
> ---
>  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" },
> +	{ }
> +};
> +
> +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,
> +};