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Message-ID: <20180313164839.GB13835@roeck-us.net>
Date: Tue, 13 Mar 2018 09:48:39 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Joel Stanley <joel@....id.au>
Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Marcus Folkesson <marcus.folkesson@...il.com>,
linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, Tomer Maimon <tmaimon77@...il.com>,
Avi Fishman <avifishman70@...il.com>,
Brendan Higgins <brendanhiggins@...gle.com>
Subject: Re: [PATCH v4 2/2] watchdog: Add Nuvoton NPCM watchdog driver
On Tue, Mar 13, 2018 at 04:47:26PM +1030, Joel Stanley wrote:
> The Nuvoton NPCM750 has a watchdog implemented as a single register
> inside the timer peripheral.
>
> This driver exposes that watchdog as a standard watchdog device with
> coarse timeout intervals, limited by the combination of prescaler and
> counter that is provided by the hardware. The calculation is taken from
> the Nuvoton vendor tree.
>
> The watchdog is left running if a bootloader had it going. The rate is
> the one specified in the device tree, or the default value (obtained
> from the datasheet).
>
> There is a pre-timeout IRQ that is wired up. This timeout always occurs
> 1024 clocks before the timeout.
>
> Signed-off-by: Joel Stanley <joel@....id.au>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> v2:
> - Make MODULE_LICENCE gpl v2 to match SPDX
> - Remove unused struct device pointer
> - Remove unused setting of drvdata
> - Add linux/bitops.h
> - Sort includes
> - Remove unused fiq include
> - Update timeout with achieved value
> v3:
> - Calculate the time and register value separately
> - Pass device tree value through set_timeout to ensure it can
> be represented by hardware
> v4:
> - Propagate return code from platform_get_irq
> ---
> drivers/watchdog/Kconfig | 11 ++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/npcm_wdt.c | 254 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 266 insertions(+)
> create mode 100644 drivers/watchdog/npcm_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index aff773bcebdb..0c1cc68894e6 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -513,6 +513,17 @@ config COH901327_WATCHDOG
> This watchdog is used to reset the system and thus cannot be
> compiled as a module.
>
> +config NPCM7XX_WATCHDOG
> + bool "Nuvoton NPCM750 watchdog"
> + depends on ARCH_NPCM || COMPILE_TEST
> + default y if ARCH_NPCM750
> + select WATCHDOG_CORE
> + help
> + Say Y here to include Watchdog timer support for the
> + watchdog embedded into the NPCM7xx.
> + This watchdog is used to reset the system and thus cannot be
> + compiled as a module.
> +
> config TWL4030_WATCHDOG
> tristate "TWL4030 Watchdog"
> depends on TWL4030_CORE
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 0474d38aa854..97a5afb5cad2 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -61,6 +61,7 @@ obj-$(CONFIG_ORION_WATCHDOG) += orion_wdt.o
> obj-$(CONFIG_SUNXI_WATCHDOG) += sunxi_wdt.o
> obj-$(CONFIG_RN5T618_WATCHDOG) += rn5t618_wdt.o
> obj-$(CONFIG_COH901327_WATCHDOG) += coh901327_wdt.o
> +obj-$(CONFIG_NPCM7XX_WATCHDOG) += npcm_wdt.o
> obj-$(CONFIG_STMP3XXX_RTC_WATCHDOG) += stmp3xxx_rtc_wdt.o
> obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
> obj-$(CONFIG_TS4800_WATCHDOG) += ts4800_wdt.o
> diff --git a/drivers/watchdog/npcm_wdt.c b/drivers/watchdog/npcm_wdt.c
> new file mode 100644
> index 000000000000..0d4213652ecc
> --- /dev/null
> +++ b/drivers/watchdog/npcm_wdt.c
> @@ -0,0 +1,254 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2018 Nuvoton Technology corporation.
> +// Copyright (c) 2018 IBM Corp.
> +
> +#include <linux/bitops.h>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/watchdog.h>
> +
> +#define NPCM_WTCR 0x1C
> +
> +#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 */
> +
> +/*
> + * Watchdog timeouts
> + *
> + * 170 msec: WTCLK=01 WTIS=00 VAL= 0x400
> + * 670 msec: WTCLK=01 WTIS=01 VAL= 0x410
> + * 1360 msec: WTCLK=10 WTIS=00 VAL= 0x800
> + * 2700 msec: WTCLK=01 WTIS=10 VAL= 0x420
> + * 5360 msec: WTCLK=10 WTIS=01 VAL= 0x810
> + * 10700 msec: WTCLK=01 WTIS=11 VAL= 0x430
> + * 21600 msec: WTCLK=10 WTIS=10 VAL= 0x820
> + * 43000 msec: WTCLK=11 WTIS=00 VAL= 0xC00
> + * 85600 msec: WTCLK=10 WTIS=11 VAL= 0x830
> + * 172000 msec: WTCLK=11 WTIS=01 VAL= 0xC10
> + * 687000 msec: WTCLK=11 WTIS=10 VAL= 0xC20
> + * 2750000 msec: WTCLK=11 WTIS=11 VAL= 0xC30
> + */
> +
> +struct npcm_wdt {
> + struct watchdog_device wdd;
> + void __iomem *reg;
> +};
> +
> +static inline struct npcm_wdt *to_npcm_wdt(struct watchdog_device *wdd)
> +{
> + return container_of(wdd, struct npcm_wdt, wdd);
> +}
> +
> +static int npcm_wdt_ping(struct watchdog_device *wdd)
> +{
> + struct npcm_wdt *wdt = to_npcm_wdt(wdd);
> + u32 val;
> +
> + val = readl(wdt->reg);
> + writel(val | NPCM_WTR, wdt->reg);
> +
> + return 0;
> +}
> +
> +static int npcm_wdt_start(struct watchdog_device *wdd)
> +{
> + struct npcm_wdt *wdt = to_npcm_wdt(wdd);
> + u32 val;
> +
> + if (wdd->timeout < 2)
> + val = 0x800;
> + else if (wdd->timeout < 3)
> + val = 0x420;
> + else if (wdd->timeout < 6)
> + val = 0x810;
> + else if (wdd->timeout < 11)
> + val = 0x430;
> + else if (wdd->timeout < 22)
> + val = 0x820;
> + else if (wdd->timeout < 44)
> + val = 0xC00;
> + else if (wdd->timeout < 87)
> + val = 0x830;
> + else if (wdd->timeout < 173)
> + val = 0xC10;
> + else if (wdd->timeout < 688)
> + val = 0xC20;
> + else
> + val = 0xC30;
> +
> + val |= NPCM_WTRE | NPCM_WTE | NPCM_WTR | NPCM_WTIE;
> +
> + writel(val, wdt->reg);
> +
> + return 0;
> +}
> +
> +static int npcm_wdt_stop(struct watchdog_device *wdd)
> +{
> + struct npcm_wdt *wdt = to_npcm_wdt(wdd);
> +
> + writel(0, wdt->reg);
> +
> + return 0;
> +}
> +
> +
> +static int npcm_wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + if (timeout < 2)
> + wdd->timeout = 1;
> + else if (timeout < 3)
> + wdd->timeout = 2;
> + else if (timeout < 6)
> + wdd->timeout = 5;
> + else if (timeout < 11)
> + wdd->timeout = 10;
> + else if (timeout < 22)
> + wdd->timeout = 21;
> + else if (timeout < 44)
> + wdd->timeout = 43;
> + else if (timeout < 87)
> + wdd->timeout = 86;
> + else if (timeout < 173)
> + wdd->timeout = 172;
> + else if (timeout < 688)
> + wdd->timeout = 687;
> + else
> + wdd->timeout = 2750;
> +
> + if (watchdog_active(wdd))
> + npcm_wdt_start(wdd);
> +
> + return 0;
> +}
> +
> +static irqreturn_t npcm_wdt_interrupt(int irq, void *data)
> +{
> + struct npcm_wdt *wdt = data;
> +
> + watchdog_notify_pretimeout(&wdt->wdd);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int npcm_wdt_restart(struct watchdog_device *wdd,
> + unsigned long action, void *data)
> +{
> + struct npcm_wdt *wdt = to_npcm_wdt(wdd);
> +
> + writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, wdt->reg);
> + udelay(1000);
> +
> + return 0;
> +}
> +
> +static bool npcm_is_running(struct watchdog_device *wdd)
> +{
> + struct npcm_wdt *wdt = to_npcm_wdt(wdd);
> +
> + return readl(wdt->reg) & NPCM_WTE;
> +}
> +
> +static const struct watchdog_info npcm_wdt_info = {
> + .identity = KBUILD_MODNAME,
> + .options = WDIOF_SETTIMEOUT
> + | WDIOF_KEEPALIVEPING
> + | WDIOF_MAGICCLOSE,
> +};
> +
> +static const struct watchdog_ops npcm_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = npcm_wdt_start,
> + .stop = npcm_wdt_stop,
> + .ping = npcm_wdt_ping,
> + .set_timeout = npcm_wdt_set_timeout,
> + .restart = npcm_wdt_restart,
> +};
> +
> +static int npcm_wdt_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct npcm_wdt *wdt;
> + struct resource *res;
> + int irq;
> + int ret;
> +
> + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + wdt->reg = devm_ioremap_resource(dev, res);
> + if (IS_ERR(wdt->reg))
> + return PTR_ERR(wdt->reg);
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0)
> + return irq;
> +
> + wdt->wdd.info = &npcm_wdt_info;
> + wdt->wdd.ops = &npcm_wdt_ops;
> + wdt->wdd.min_timeout = 1;
> + wdt->wdd.max_timeout = 2750;
> + wdt->wdd.parent = dev;
> +
> + wdt->wdd.timeout = 86;
> + watchdog_init_timeout(&wdt->wdd, 0, dev);
> +
> + /* Ensure timeout is able to be represented by the hardware */
> + npcm_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout);
> +
> + if (npcm_is_running(&wdt->wdd)) {
> + /* Restart with the default or device-tree specified timeout */
> + npcm_wdt_start(&wdt->wdd);
> + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
> + }
> +
> + ret = devm_request_irq(dev, irq, npcm_wdt_interrupt, 0,
> + "watchdog", wdt);
> + if (ret)
> + return ret;
> +
> + ret = devm_watchdog_register_device(dev, &wdt->wdd);
> + if (ret) {
> + dev_err(dev, "failed to register watchdog\n");
> + return ret;
> + }
> +
> + dev_info(dev, "NPCM watchdog driver enabled\n");
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id npcm_wdt_match[] = {
> + {.compatible = "nuvoton,npcm750-wdt"},
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, npcm_wdt_match);
> +#endif
> +
> +static struct platform_driver npcm_wdt_driver = {
> + .probe = npcm_wdt_probe,
> + .driver = {
> + .name = "npcm-wdt",
> + .of_match_table = of_match_ptr(npcm_wdt_match),
> + },
> +};
> +module_platform_driver(npcm_wdt_driver);
> +
> +MODULE_AUTHOR("Joel Stanley");
> +MODULE_DESCRIPTION("Watchdog driver for NPCM");
> +MODULE_LICENSE("GPL v2");
> --
> 2.15.1
>
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