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Message-ID: <0f0b654b-306e-86a0-5cef-b341533526c0@st.com>
Date: Thu, 6 Apr 2017 12:24:19 +0000
From: Yannick FERTRE <yannick.fertre@...com>
To: Guenter Roeck <linux@...ck-us.net>,
Wim Van Sebroeck <wim@...ana.be>,
"Rob Herring" <robh+dt@...nel.org>,
Alexandre TORGUE <alexandre.torgue@...com>,
Benjamin GAIGNARD <benjamin.gaignard@...com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>
CC: "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Philippe CORNU <philippe.cornu@...com>,
Gabriel FERNANDEZ <gabriel.fernandez@...com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 2/5] drivers: watchdog: Add STM32 IWDG driver
Hi Guenter,
thanks for your help.
Best regards
On 04/02/2017 01:48 PM, Guenter Roeck wrote:
> On 03/30/2017 08:15 AM, Yannick Fertre wrote:
>> This patch adds IWDG (Independent WatchDoG) support for STM32 platform.
>>
>> Signed-off-by: Yannick FERTRE <yannick.fertre@...com>
>> ---
>> drivers/watchdog/Kconfig | 12 ++
>> drivers/watchdog/Makefile | 1 +
>> drivers/watchdog/stm32_iwdg.c | 260
>> ++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 273 insertions(+)
>> create mode 100644 drivers/watchdog/stm32_iwdg.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 52a70ee..d014deb 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -744,6 +744,18 @@ 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 support for the watchdog timer
>> + in stm32 SoCs.
>> +
>> + 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..629c305
>> --- /dev/null
>> +++ b/drivers/watchdog/stm32_iwdg.c
>> @@ -0,0 +1,260 @@
>> +/*
>> + * Driver for STM32 Independent Watchdog
>> + *
>> + * Copyright (C) Yannick Fertre 2017
>> + * Author: Yannick Fertre <yannick.fertre@...com>
>> + *
>> + * This driver is based on tegra_wdt.c
>> + *
>> + * License terms: GNU General Public License (GPL), version 2
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/watchdog.h>
>> +
>> +/* watchdog trigger timeout, in seconds */
>> +#define WDT_MIN_TIMEOUT 1
>> +#define WDT_MAX_TIMEOUT 32
>> +#define WDT_DEFAULT_TIMEOUT 30
>> +
>> +/* 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;
>> + void __iomem *regs;
>> + struct clk *clk;
>> + unsigned int rate;
>> +};
>> +
>> +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(wdd->parent, "%s\n", __func__);
>> +
>> + /* enable watchdog */
>> + reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA);
>> + reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE);
>> +
>> + /* prescaler fixed to 256 */
>> + reload = (wdd->timeout * wdt->rate) / 256;
>> + if (reload > RLR_MAX + 1)
>> + reload = RLR_MAX + 1;
>> +
>> + /* set prescaler & reload registers */
>> + 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(wdd->parent,
>> + "Fail to set prescaler or reload registers\n");
>> + return ret;
>> + }
>> +
>> + /* reload watchdog */
>> + reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_iwdg_ping(struct watchdog_device *wdd)
>> +{
>> + struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd);
>> +
>> + dev_dbg(wdd->parent, "%s\n", __func__);
>> +
>> + /* reload watchdog */
>> + reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD);
>> +
>> + return 0;
>> +}
>> +
>> +static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
>> + unsigned int timeout)
>> +{
>> + dev_dbg(wdd->parent, "%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,
>> + .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 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->clk = clk;
>> + wdt->rate = clk_get_rate(clk);
>> +
>> + /* Initialize struct watchdog_device. */
>> + wdd = &wdt->wdd;
>> + wdd->info = &stm32_iwdg_info;
>> + wdd->ops = &stm32_iwdg_ops;
>> + wdd->min_timeout = WDT_MIN_TIMEOUT;
>> + wdd->max_timeout = WDT_MAX_TIMEOUT;
>> + wdd->max_hw_heartbeat_ms = WDT_MAX_TIMEOUT;
>
> This would have to be in milli-seconds. Also only provide max_timeout
> or max_hw_heartbeat_ms, but not both.
>
Fix in V5
>> + wdd->parent = &pdev->dev;
>> +
>> + watchdog_set_drvdata(wdd, wdt);
>> + watchdog_set_nowayout(wdd, true);
>> +
>> + ret = watchdog_init_timeout(wdd, WDT_DEFAULT_TIMEOUT, &pdev->dev);
>
> Timeout parameter should be 0 to give the core a chance to pick up a
> timeout
> from fdt if specified. Otherwise the call is quite useless.
Fix in V5
>
>> + if (ret)
>> + dev_warn(&pdev->dev,
>> + "unable to set timeout value, using default\n");
>> +
>> + ret = watchdog_register_device(wdd);
>> + if (ret) {
>> + dev_err(&pdev->dev,
>> + "failed to register watchdog device\n");
>> + goto err;
>> + }
>> +
>> + platform_set_drvdata(pdev, wdt);
>> +
>> + 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);
>> +
>> + 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 <yannick.fertre@...com>");
>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog
>> Driver");
>> +MODULE_LICENSE("GPL v2");
>>
>
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