Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752258AbdC2DPW (ORCPT ); Tue, 28 Mar 2017 23:15:22 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:37555 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751553AbdC2DPT (ORCPT ); Tue, 28 Mar 2017 23:15:19 -0400 Subject: Re: [PATCH v3 2/5] drivers: watchdog: Add STM32 IWDG driver To: Yannick Fertre , Wim Van Sebroeck , Rob Herring , Alexandre TORGUE , Benjamin Gaignard , Maxime Coquelin References: <1490195083-25117-1-git-send-email-yannick.fertre@st.com> <1490195083-25117-3-git-send-email-yannick.fertre@st.com> Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, Philippe Cornu , Gabriel FERNANDEZ , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org From: Guenter Roeck Message-ID: Date: Tue, 28 Mar 2017 20:15:15 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <1490195083-25117-3-git-send-email-yannick.fertre@st.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10747 Lines: 375 On 03/22/2017 08:04 AM, Yannick Fertre wrote: > This patch adds IWDG (Independent WatchDoG) support for STM32 platform. > > Change-Id: Iab218745fc25566f12558fae7f52e2f8c21db74e No gerrit tags, please. > Signed-off-by: Yannick FERTRE > --- > drivers/watchdog/Kconfig | 11 ++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/stm32_iwdg.c | 289 ++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 301 insertions(+) > create mode 100644 drivers/watchdog/stm32_iwdg.c > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index 52a70ee..d9745a5 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -744,6 +744,17 @@ config ZX2967_WATCHDOG > To compile this driver as a module, choose M here: the > module will be called zx2967_wdt. > > +config STM32_WATCHDOG > + tristate "STM32 Independent WatchDoG (IWDG) support" > + depends on ARCH_STM32 > + select WATCHDOG_CORE > + default y > + help > + Say Y here to include Watchdog timer support. ... for . > + > + To compile this driver as a module, choose M here: the > + module will be called stm32_iwdg. > + > # AVR32 Architecture > > config AT32AP700X_WDT > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index a2126e2..a35e423 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -84,6 +84,7 @@ obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o > obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o > obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o > obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o > +obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o > > # AVR32 Architecture > obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o > diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c > new file mode 100644 > index 0000000..507dfc4 > --- /dev/null > +++ b/drivers/watchdog/stm32_iwdg.c > @@ -0,0 +1,289 @@ > +/* > + * Driver for STM32 Independent Watchdog > + * > + * Copyright (C) Yannick Fertre 2017 > + * Author: Yannick Fertre > + * > + * This driver is based on tegra_wdt.c > + * > + * License terms: GNU General Public License (GPL), version 2 > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +/* minimum watchdog trigger timeout, in seconds */ > +#define MIN_WDT_TIMEOUT 1 > + > +/* IWDG registers */ > +#define IWDG_KR 0x00 /* Key register */ > +#define IWDG_PR 0x04 /* Prescaler Register */ > +#define IWDG_RLR 0x08 /* ReLoad Register */ > +#define IWDG_SR 0x0C /* Status Register */ > +#define IWDG_WINR 0x10 /* Windows Register */ > + > +/* IWDG_KR register bit mask */ > +#define KR_KEY_RELOAD 0xAAAA /* reload counter enable */ > +#define KR_KEY_ENABLE 0xCCCC /* peripheral enable */ > +#define KR_KEY_EWA 0x5555 /* write access enable */ > +#define KR_KEY_DWA 0x0000 /* write access disable */ > + > +/* IWDG_PR register bit values */ > +#define PR_4 0x00 /* prescaler set to 4 */ > +#define PR_8 0x01 /* prescaler set to 8 */ > +#define PR_16 0x02 /* prescaler set to 16 */ > +#define PR_32 0x03 /* prescaler set to 32 */ > +#define PR_64 0x04 /* prescaler set to 64 */ > +#define PR_128 0x05 /* prescaler set to 128 */ > +#define PR_256 0x06 /* prescaler set to 256 */ > + > +/* IWDG_RLR register values */ > +#define RLR_MAX 0xFFF /* max value supported by reload register */ > + > +/* IWDG_SR register bit mask */ > +#define FLAG_PVU BIT(0) /* Watchdog prescaler value update */ > +#define FLAG_RVU BIT(1) /* Watchdog counter reload value update */ > + > +/* set timeout to 100000 us */ > +#define TIMEOUT_US 100000 > +#define SLEEP_US 1000 > + > +struct stm32_iwdg { > + struct watchdog_device wdd; > + struct device *dev; > + void __iomem *regs; > + struct clk *clk; > + unsigned int rate; > +}; > + > +static int heartbeat = MIN_WDT_TIMEOUT; > +module_param(heartbeat, int, 0x0); > +MODULE_PARM_DESC(heartbeat, > + "Watchdog heartbeats in seconds. (default = " > + __MODULE_STRING(WDT_HEARTBEAT) ")"); > + > +static inline u32 reg_read(void __iomem *base, u32 reg) > +{ > + return readl_relaxed(base + reg); > +} > + > +static inline void reg_write(void __iomem *base, u32 reg, u32 val) > +{ > + writel_relaxed(val, base + reg); > +} > + > +static int stm32_iwdg_start(struct watchdog_device *wdd) > +{ > + struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); > + u32 val = FLAG_PVU | FLAG_RVU; > + u32 reload; > + int ret; > + > + dev_dbg(wdt->dev, "%s\n", __func__); > + > + /* prescaler fixed to 256 */ > + reload = (wdd->timeout * wdt->rate) / 256; > + if (reload > RLR_MAX + 1) { > + dev_err(wdt->dev, > + "Watchdog doesn't support reload value: %d\n", reload); > + return -EINVAL; > + } This should not happen if min_timeout and max_timeout are set properly. > + > + /* enable watchdog */ > + reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); > + > + /* set prescaler & reload registers */ > + reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); > + reg_write(wdt->regs, IWDG_PR, PR_256); /* prescaler fix to 256 */ > + reg_write(wdt->regs, IWDG_RLR, reload - 1); > + > + /* wait for the registers to be updated (max 100ms) */ > + ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, val, > + !(val & (FLAG_PVU | FLAG_RVU)), > + SLEEP_US, TIMEOUT_US); > + if (ret) { > + dev_err(wdt->dev, > + "Fail to set prescaler or reload registers\n"); > + return -EINVAL; Any reason for overriding the return value ? > + } > + > + /* reload watchdog */ > + reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD); > + > + return 0; > +} > + > +static int stm32_iwdg_stop(struct watchdog_device *wdd) > +{ > + struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); > + > + if (watchdog_active(wdd)) { > + dev_err(wdt->dev, > + "Watchdog can't be stopped once started(no way out)\n"); > + return -EPERM; The infrastructure takes care of this. Don't provide a stop function, and provide the maximum hardware timeout. > + } > + > + return 0; > +} > + > +static int stm32_iwdg_ping(struct watchdog_device *wdd) > +{ > + struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); > + > + dev_dbg(wdt->dev, "%s\n", __func__); > + > + reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD); > + > + return 0; > +} > + > +static int stm32_iwdg_set_timeout(struct watchdog_device *wdd, > + unsigned int timeout) > +{ > + struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); > + > + dev_dbg(wdt->dev, "%s timeout: %d sec\n", __func__, timeout); > + > + wdd->timeout = timeout; > + > + if (watchdog_active(wdd)) > + return stm32_iwdg_start(wdd); > + > + return 0; > +} > + > +static const struct watchdog_info stm32_iwdg_info = { > + .options = WDIOF_SETTIMEOUT | > + WDIOF_MAGICCLOSE | > + WDIOF_KEEPALIVEPING, > + .identity = "STM32 Independent Watchdog", > +}; > + > +static struct watchdog_ops stm32_iwdg_ops = { > + .owner = THIS_MODULE, > + .start = stm32_iwdg_start, > + .stop = stm32_iwdg_stop, > + .ping = stm32_iwdg_ping, > + .set_timeout = stm32_iwdg_set_timeout, > +}; > + > +static int stm32_iwdg_probe(struct platform_device *pdev) > +{ > + struct watchdog_device *wdd; > + struct stm32_iwdg *wdt; > + struct resource *res; > + void __iomem *regs; > + struct clk *clk; > + int max_wdt_timeout; > + int ret; > + > + /* This is the timer base. */ > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + regs = devm_ioremap_resource(&pdev->dev, res); > + if (IS_ERR(regs)) { > + dev_err(&pdev->dev, "Could not get resource\n"); > + return PTR_ERR(regs); > + } > + > + clk = devm_clk_get(&pdev->dev, NULL); > + if (IS_ERR(clk)) { > + dev_err(&pdev->dev, "Unable to get clock\n"); > + return PTR_ERR(clk); > + } > + > + ret = clk_prepare_enable(clk); > + if (ret) { > + dev_err(&pdev->dev, "Unable to prepare clock %p\n", clk); > + return ret; > + } > + > + /* > + * Allocate our watchdog driver data, which has the > + * struct watchdog_device nested within it. > + */ > + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); > + if (!wdt) { > + ret = -ENOMEM; > + goto err; > + } > + > + /* Initialize struct stm32_iwdg. */ > + wdt->regs = regs; > + wdt->dev = &pdev->dev; > + wdt->clk = clk; > + /* > + * iwdg is clocked by its own dedicated low-speed clock (LSI) > + * at 32khz. > + */ > + wdt->rate = 32 * 1024; Why not clk_get_rate() ? > + > + /* get max timeout & set heartbeat */ > + max_wdt_timeout = ((RLR_MAX + 1) * 256) / wdt->rate; > + heartbeat = max_wdt_timeout; What is the value of overwriting this variable ? Why don't you just use max_wdt_timeout, and what is the point of making heartbeat configurable if you overwrite it anyway ? I would suggest to use watchdog_init_timeout() to set optional non-default timeout values, especially since this also enables getting the timeout value from devicetree. > + > + /* Initialize struct watchdog_device. */ > + wdd = &wdt->wdd; > + wdd->timeout = heartbeat; > + wdd->info = &stm32_iwdg_info; > + wdd->ops = &stm32_iwdg_ops; > + wdd->min_timeout = MIN_WDT_TIMEOUT; > + wdd->max_timeout = max_wdt_timeout; You might want to consider setting max_hw_heartbeat_ms instead and drop the stop function. > + watchdog_set_drvdata(wdd, wdt); > + watchdog_set_nowayout(wdd, true); > + > + ret = watchdog_register_device(wdd); > + if (ret) { > + dev_err(&pdev->dev, > + "failed to register watchdog device\n"); > + goto err; > + } > + > + platform_set_drvdata(pdev, wdt); > + > + dev_info(&pdev->dev, > + "initialized (heartbeat = %d sec)\n", heartbeat); > + return 0; > + > +err: > + clk_disable_unprepare(clk); > + return ret; > +} > + > +static int stm32_iwdg_remove(struct platform_device *pdev) > +{ > + struct stm32_iwdg *wdt = platform_get_drvdata(pdev); > + > + watchdog_unregister_device(&wdt->wdd); > + clk_disable_unprepare(wdt->clk); > + > + dev_info(&pdev->dev, "removed watchdog device\n"); Is this message really useful ? I think it is just noise. > + return 0; > +} > + > +static const struct of_device_id stm32_iwdg_of_match[] = { > + { .compatible = "st,stm32-iwdg" }, > + { /* end node */ } > +}; > +MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); > + > +static struct platform_driver stm32_iwdg_driver = { > + .probe = stm32_iwdg_probe, > + .remove = stm32_iwdg_remove, > + .driver = { > + .name = "iwdg", > + .of_match_table = stm32_iwdg_of_match, > + }, > +}; > +module_platform_driver(stm32_iwdg_driver); > + > +MODULE_AUTHOR("Yannick Fertre "); > +MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver"); > +MODULE_LICENSE("GPL v2"); >