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Sun, 20 Oct 2019 09:56:31 -0700 (PDT) Subject: Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver To: Xingyu Chen , Wim Van Sebroeck , Kevin Hilman , Neil Armstrong Cc: Rob Herring , Jerome Brunet , Qianggui Song , Jianxin Pan , Jian Hu , linux-watchdog@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <1571387622-35132-1-git-send-email-xingyu.chen@amlogic.com> <1571387622-35132-4-git-send-email-xingyu.chen@amlogic.com> From: Guenter Roeck Message-ID: <7397f6db-1dc8-3abd-41ff-2e47323c7ffa@roeck-us.net> Date: Sun, 20 Oct 2019 09:56:29 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1571387622-35132-4-git-send-email-xingyu.chen@amlogic.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/18/19 1:33 AM, Xingyu Chen wrote: > The watchdog controller on the Meson-A/C series SoCs is moved to secure > world, watchdog operation needs to be done in secure EL3 mode via ATF, > Non-secure world can call SMC instruction to trap to AFT for watchdog > operation. > > Signed-off-by: Xingyu Chen > --- > drivers/watchdog/Kconfig | 17 ++++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/meson_sec_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 205 insertions(+) > create mode 100644 drivers/watchdog/meson_sec_wdt.c > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index 58e7c10..e84be42 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG > To compile this driver as a module, choose M here: the > module will be called meson_gxbb_wdt. > > +config MESON_SEC_WATCHDOG > + tristate "Amlogic Meson Secure watchdog support" > + depends on MESON_SM > + depends on ARCH_MESON || COMPILE_TEST This dependency is pointless. MESON_SM already depends on ARCH_MESON, thus specifying "COMPILE_TEST" here adds no value but only creates confusion. > + select WATCHDOG_CORE > + help > + The watchdog controller on the Meson-A/C series SoCs is moved to > + secure world, watchdog operation needs to be done in secure EL3 > + mode via ATF, non-secure world can call SMC instruction to trap > + to ATF for the watchdog operation. > + > + Say Y here if watchdog controller on Meson SoCs is located in > + secure world. > + > + To compile this driver as a module, choose M here: the > + module will be called meson_sec_wdt. > + > config MESON_WATCHDOG > tristate "Amlogic Meson SoCs watchdog support" > depends on ARCH_MESON || COMPILE_TEST > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index 2ee352b..5e6b73d 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -78,6 +78,7 @@ obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o > obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o > obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o > obj-$(CONFIG_MESON_GXBB_WATCHDOG) += meson_gxbb_wdt.o > +obj-$(CONFIG_MESON_SEC_WATCHDOG) += meson_sec_wdt.o > obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o > obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o > obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o > diff --git a/drivers/watchdog/meson_sec_wdt.c b/drivers/watchdog/meson_sec_wdt.c > new file mode 100644 > index 00000000..86bd87c > --- /dev/null > +++ b/drivers/watchdog/meson_sec_wdt.c > @@ -0,0 +1,187 @@ > +// SPDX-License-Identifier: (GPL-2.0+ OR MIT) > +/* > + * Copyright (c) 2019 Amlogic, Inc. All rights reserved. > + * Author: Xingyu Chen > + * > + */ > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define MESON_SIP_WDT_DISABLE 0x1 > +#define MESON_SIP_WDT_ENABLE 0x2 > +#define MESON_SIP_WDT_PING 0x3 > +#define MESON_SIP_WDT_INIT 0x4 > +#define MESON_SIP_WDT_RESETNOW 0x5 > +#define MESON_SIP_WDT_SETTIMEOUT 0x6 > +#define MESON_SIP_WDT_GETTIMELEFT 0x7 > + > +#define DEFAULT_TIMEOUT 30 /* seconds */ > + > +/* > + * Watchdog timer tick is set to 1ms in secfw side, and tick count is > + * stored in the bit[16-31] of WATCHDOG_CNT register, so the maximum > + * timeout value is 0xffff ms. > + */ > +#define MAX_TIMEOUT_MS 0xFFFF > + > +struct meson_sec_wdt { > + struct watchdog_device wdt_dev; > + struct meson_sm_firmware *fw; > +}; > + > +static int meson_sec_wdt_start(struct watchdog_device *wdt_dev) > +{ > + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev); > + > + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL, > + MESON_SIP_WDT_ENABLE, 0, 0, 0, 0); > +} > + > +static int meson_sec_wdt_stop(struct watchdog_device *wdt_dev) > +{ > + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev); > + > + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL, > + MESON_SIP_WDT_DISABLE, 0, 0, 0, 0); > +} > + > +static int meson_sec_wdt_ping(struct watchdog_device *wdt_dev) > +{ > + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev); > + > + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL, > + MESON_SIP_WDT_PING, 0, 0, 0, 0); > +} > + > +static int meson_sec_wdt_set_timeout(struct watchdog_device *wdt_dev, > + unsigned int timeout) > +{ > + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev); > + > + wdt_dev->timeout = timeout; > + > + return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL, > + MESON_SIP_WDT_SETTIMEOUT, > + wdt_dev->timeout, 0, 0, 0); > +} > + > +static unsigned int meson_sec_wdt_get_timeleft(struct watchdog_device *wdt_dev) > +{ > + int ret; > + unsigned int timeleft; > + struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev); > + > + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, &timeleft, > + MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0); > + > + if (ret) > + return ret; Meh, that doesn't work. I just realized that the return type is unsigned, so returning a negative error code is pointless. Guess we'll have to live with returning 0 in this case after all. I wonder if we should fix the API and return an integer (with negative error code), but that is a different question. Sorry for the confusion - I should have noticed that before. > + > + return timeleft; > +} > + > +static const struct watchdog_ops meson_sec_wdt_ops = { > + .start = meson_sec_wdt_start, > + .stop = meson_sec_wdt_stop, > + .ping = meson_sec_wdt_ping, > + .set_timeout = meson_sec_wdt_set_timeout, > + .get_timeleft = meson_sec_wdt_get_timeleft, > +}; > + > +static const struct watchdog_info meson_sec_wdt_info = { > + .identity = "Meson Secure Watchdog Timer", > + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, > +}; > + > +static int __maybe_unused meson_sec_wdt_resume(struct device *dev) > +{ > + struct meson_sec_wdt *data = dev_get_drvdata(dev); > + > + if (watchdog_active(&data->wdt_dev)) > + return meson_sec_wdt_start(&data->wdt_dev); > + > + return 0; > +} > + > +static int __maybe_unused meson_sec_wdt_suspend(struct device *dev) > +{ > + struct meson_sec_wdt *data = dev_get_drvdata(dev); > + > + if (watchdog_active(&data->wdt_dev)) > + return meson_sec_wdt_stop(&data->wdt_dev); > + > + return 0; > +} > + > +static const struct dev_pm_ops meson_sec_wdt_pm_ops = { > + SET_SYSTEM_SLEEP_PM_OPS(meson_sec_wdt_suspend, meson_sec_wdt_resume) > +}; > + > +static const struct of_device_id meson_sec_wdt_dt_ids[] = { > + { .compatible = "amlogic,meson-sec-wdt", }, > + { /* sentinel */ }, > +}; > +MODULE_DEVICE_TABLE(of, meson_sec_wdt_dt_ids); > + > +static int meson_sec_wdt_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct meson_sec_wdt *data; > + struct device_node *sm_np; > + int ret; > + > + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + sm_np = of_parse_phandle(pdev->dev.of_node, "secure-monitor", 0); > + if (!sm_np) { > + dev_err(&pdev->dev, "no secure-monitor node\n"); > + return -EINVAL; > + } > + > + data->fw = meson_sm_get(sm_np); > + of_node_put(sm_np); > + if (!data->fw) > + return -EPROBE_DEFER; > + > + platform_set_drvdata(pdev, data); > + > + data->wdt_dev.parent = dev; > + data->wdt_dev.info = &meson_sec_wdt_info; > + data->wdt_dev.ops = &meson_sec_wdt_ops; > + data->wdt_dev.max_hw_heartbeat_ms = MAX_TIMEOUT_MS; > + data->wdt_dev.min_timeout = 1; > + data->wdt_dev.timeout = DEFAULT_TIMEOUT; > + watchdog_set_drvdata(&data->wdt_dev, data); > + > + ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL, > + MESON_SIP_WDT_INIT, > + data->wdt_dev.timeout, 0, 0, 0); > + if (ret) > + return ret; > + > + watchdog_stop_on_reboot(&data->wdt_dev); > + > + return devm_watchdog_register_device(dev, &data->wdt_dev); > +} > + > +static struct platform_driver meson_sec_wdt_driver = { > + .probe = meson_sec_wdt_probe, > + .driver = { > + .name = "meson-sec-wdt", > + .pm = &meson_sec_wdt_pm_ops, > + .of_match_table = meson_sec_wdt_dt_ids, > + }, > +}; > + > +module_platform_driver(meson_sec_wdt_driver); > + > +MODULE_AUTHOR("Xingyu Chen "); > +MODULE_DESCRIPTION("Amlogic Secure Watchdog Timer Driver"); > +MODULE_LICENSE("Dual MIT/GPL"); >