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Tue, 09 Jun 2020 06:42:51 -0700 (PDT) Subject: Re: [PATCH 2/2] watchdog: intel: Watchdog timer support on Lightning Mountain To: Dilip Kota , wim@linux-watchdog.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, robbh@kernel.org Cc: linux-kernel@vger.kernel.org, andriy.shevchenko@intel.com, cheol.yong.kim@intel.com, qi-ming.wu@intel.com, yixin.zhu@intel.com References: <220609c6aec3dbd06585897ddcfdde277c823cac.1591584255.git.eswara.kota@linux.intel.com> <61d256e7-88ca-ac89-9c80-132c0d2de4a8@roeck-us.net> From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= Message-ID: <8cb36dce-bd2e-2581-5644-fc73e4d94316@roeck-us.net> Date: Tue, 9 Jun 2020 06:42:49 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On 6/9/20 1:57 AM, Dilip Kota wrote: > > On 6/8/2020 9:36 PM, Guenter Roeck wrote: >> On 6/7/20 10:49 PM, Dilip Kota wrote: >>> On Intel Lightning Mountain SoC, General Purpose Timer Counter(GPTC) >>> programmable as clocksource, real time clock or watchdog timer. >>> >>> This driver configures GPTC as Watchdog timer and triggers reset signal >>> to CPU on timeout. >>> >>> Signed-off-by: Dilip Kota >>> --- >>>   drivers/watchdog/Kconfig              |  13 ++ >>>   drivers/watchdog/Makefile             |   1 + >>>   drivers/watchdog/intel_lgm_gptc_wdt.c | 420 ++++++++++++++++++++++++++++++++++ >>>   3 files changed, 434 insertions(+) >>>   create mode 100644 drivers/watchdog/intel_lgm_gptc_wdt.c >>> >>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig >>> index 0663c604bd642..8009c11e75dda 100644 >>> --- a/drivers/watchdog/Kconfig >>> +++ b/drivers/watchdog/Kconfig >>> @@ -1789,6 +1789,19 @@ config IMGPDC_WDT >>>         To compile this driver as a loadable module, choose M here. >>>         The module will be called imgpdc_wdt. >>>   +config INTEL_LGM_GPTC_WDT >>> +    tristate "INTEL LGM SoC Watchdog" >>> +    depends on X86 || COMPILE_TEST >>> +    depends on OF && HAS_IOMEM >>> +    select REGMAP >>> +    select MFD_SYSCON >>> +    select WATCHDOG_CORE >>> +    help >>> +      Driver for Watchdog Timer on Intel Lightning Mountain SoC. >>> + >>> +      To compile this driver as a loadable module, choose M here. >>> +      The module will be called intel_lgm_gptc_wdt. >>> + >>>   config LANTIQ_WDT >>>       tristate "Lantiq SoC watchdog" >>>       depends on LANTIQ >>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile >>> index 6de2e4ceef190..92c99e4c46eb7 100644 >>> --- a/drivers/watchdog/Makefile >>> +++ b/drivers/watchdog/Makefile >>> @@ -166,6 +166,7 @@ obj-$(CONFIG_TXX9_WDT) += txx9wdt.o >>>   obj-$(CONFIG_OCTEON_WDT) += octeon-wdt.o >>>   octeon-wdt-y := octeon-wdt-main.o octeon-wdt-nmi.o >>>   obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o >>> +obj-$(CONFIG_INTEL_LGM_GPTC_WDT) += intel_lgm_gptc_wdt.o >>>   obj-$(CONFIG_LOONGSON1_WDT) += loongson1_wdt.o >>>   obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o >>>   obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o >>> diff --git a/drivers/watchdog/intel_lgm_gptc_wdt.c b/drivers/watchdog/intel_lgm_gptc_wdt.c >>> new file mode 100644 >>> index 0000000000000..52be7cc194f8f >>> --- /dev/null >>> +++ b/drivers/watchdog/intel_lgm_gptc_wdt.c >>> @@ -0,0 +1,420 @@ >>> +// SPDX-License-Identifier: GPL-2.0 >>> +/* >>> + * Copyright (C) 2020 Intel Corporation. >>> + */ >>> + >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> +#include >>> + >>> +#define GPTC_CLC        0x00 >>> +#define GPTC_CLC_SUSPEND    BIT(4) >>> +#define GPTC_CLC_RMC        GENMASK(15, 8) >>> + >>> +/* divider 10 to produce 200 / 10 = 20 MHz clock */ >>> +#define CLC_RMC_DIV        10 >>> + >>> +#define GPTC_CON(X)        (0x10 + (X) * 0x20) >>> +#define GPTC_CON_CNT_UP        BIT(1) >>> +#define GPTC_CON_ONESHOT    BIT(3) >>> +#define GPTC_CON_EXT        BIT(4) >>> + >>> +#define GPTC_RUN(X)        (0x18 + (X) * 0x20) >>> +#define GPTC_RUN_EN        BIT(0) >>> +#define GPTC_RUN_STOP        BIT(1) >>> +#define GPTC_RUN_RELOAD        BIT(2) >>> + >>> +#define GPTC_RLD(X)        (0x20 + (X) * 0x20) >>> +#define GPTC_CNT(X)        (0x28 + (X) * 0x20) >>> + >>> +#define GPTC_IRNENCLR        0xF0 >>> +#define GPTC_IRNEN        0xF4 >>> +#define GPTC_IRNCR        0xFC >>> + >>> +/* Watchdog Timeout Reset register offset and bitfeilds */ >>> +#define BIA_WDT_RST_EN        0x1E0 >>> +#define BIA_WDT            BIT(6) >>> + >>> +#define MAX_TIMERID        2 >>> +#define MAX_CPUID        3 >>> +#define TIMER_MARGIN_SEC    300 >>> + >>> +static bool nowayout = WATCHDOG_NOWAYOUT; >>> +module_param(nowayout, bool, 0); >>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started\n" >>> +    " (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); >>> + >>> +struct lgm_gptc_timer { >>> +    struct lgm_gptc_wdt    *wdt_node; >>> +    struct watchdog_device    wdd; >>> +    unsigned int        tid; >>> +    unsigned int        cpuid; >>> +    unsigned int        frequency; >>> +    unsigned int        cycles; >>> +    bool            enable; >>> +}; >>> + >>> +struct lgm_gptc_wdt { >>> +    struct device        *dev; >>> +    void __iomem        *gptc_base; >>> +    struct regmap        *rst_hndl; >>> +    struct clk        *freqclk; >>> +    struct clk        *gateclk; >>> +    unsigned int        fpifreq; >>> +    enum cpuhp_state    state; >>> +}; >>> + >>> +DEFINE_PER_CPU(struct lgm_gptc_timer, lgm_timer_per_cpu); >>> + >> This is unusual. You'll have to provide a very detailed explanation >> why this is needed. > Sure will add it. > It is required for the hotplug cpu support, and hotplug cpu is added because, the cpus on Lightning Mountain SoC can be online and offline dynamically. > If CPUs come to online after the watchdog driver probe, hotplug CPU support helps to configure watchdog timer once CPU is online. > There is another watchdog in the system monitoring individual CPUs. The watchdog subsystem monitors the system, not individual CPUs. Individual CUPs are monitored with kernel/watchdog.c, and we should keep it that way. Guenter