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SubjectRe: [PATCH v3 1/2] watchdog: add Intel MID watchdog driver support
On Tue, Apr 15, 2014 at 11:41:11AM -0700, David Cohen wrote:
> Add initial Intel MID watchdog driver support.
>
> This driver is an initial implementation of generic Intel MID watchdog
> driver. Currently it supports Intel Merrifield platform.
>
> Signed-off-by: Eric Ernst <eric.ernst@intel.com>
> Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
> ---
> drivers/watchdog/Kconfig | 13 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/intel-mid_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++
> include/linux/intel-mid_wdt.h | 20 +++++

include/linux/platform_data/intel-mid_wdt.h ?

> 4 files changed, 221 insertions(+)
> create mode 100644 drivers/watchdog/intel-mid_wdt.c
> create mode 100644 include/linux/intel-mid_wdt.h
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 79d25894343a..0e110c37aa5c 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -643,6 +643,19 @@ config INTEL_SCU_WATCHDOG
>
> To compile this driver as a module, choose M here.
>
> +config INTEL_MID_WATCHDOG
> + tristate "Intel MID Watchdog Timer"
> + depends on X86_INTEL_MID
> + select WATCHDOG_CORE
> + ---help---
> + Watchdog timer driver built into the Intel SCU for Intel MID
> + Platforms.
> +
> + This driver currently supports only the watchdog evolution
> + implementation in SCU, available for Merrifield generation.
> +
> + To compile this driver as a module, choose M here.
> +
> config ITCO_WDT
> tristate "Intel TCO Timer/Watchdog"
> depends on (X86 || IA64) && PCI
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 985a66cda76f..b927e7496eb4 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -113,6 +113,7 @@ obj-$(CONFIG_W83977F_WDT) += w83977f_wdt.o
> obj-$(CONFIG_MACHZ_WDT) += machzwd.o
> obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
> obj-$(CONFIG_INTEL_SCU_WATCHDOG) += intel_scu_watchdog.o
> +obj-$(CONFIG_INTEL_MID_WATCHDOG) += intel-mid_wdt.o
>
> # M32R Architecture
>
> diff --git a/drivers/watchdog/intel-mid_wdt.c b/drivers/watchdog/intel-mid_wdt.c
> new file mode 100644
> index 000000000000..d8bf3c3cd2b7
> --- /dev/null
> +++ b/drivers/watchdog/intel-mid_wdt.c
> @@ -0,0 +1,187 @@
> +/*
> + * intel-mid_wdt: generic Intel MID SCU watchdog driver
> + *
> + * Platforms supported so far:
> + * - Merrifield only
> + *
> + * Copyright (C) 2014 Intel Corporation. All rights reserved.
> + * Contact: David Cohen <david.a.cohen@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General
> + * Public License as published by the Free Software Foundation.
> + */
> +
> +#include <linux/intel-mid_wdt.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/nmi.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +#include <asm/intel_scu_ipc.h>
> +#include <asm/intel-mid.h>
> +
> +#define IPC_WATCHDOG 0xf8
> +
> +#define MID_WDT_PRETIMEOUT 15
> +#define MID_WDT_TIMEOUT_MIN (1 + MID_WDT_PRETIMEOUT)
> +#define MID_WDT_TIMEOUT_MAX 170
> +#define MID_WDT_DEFAULT_TIMEOUT 90
> +
> +/* SCU watchdog messages */
> +enum {
> + SCU_WATCHDOG_START = 0,
> + SCU_WATCHDOG_STOP,
> + SCU_WATCHDOG_KEEPALIVE,
> +};
> +
> +static inline int wdt_command(int sub, u32 *in, int inlen)
> +{
> + return intel_scu_ipc_command(IPC_WATCHDOG, sub, in, inlen, NULL, 0);
> +}
> +
> +static int wdt_start(struct watchdog_device *wd)
> +{
> + int ret, in_size;
> + int timeout = wd->timeout;
> + struct ipc_wd_start {
> + u32 pretimeout;
> + u32 timeout;
> + } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
> +
> + /*
> + * SCU expects the input size for watchdog IPC to
> + * be based on double-word
> + */
> + in_size = (sizeof(ipc_wd_start) + 3) / 4;
> +
DIV_ROUND_UP ?

Not sure how "double-word" matches the calculation. What is a "double-word" ?
4 bytes ?

> + ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
> + if (ret) {
> + struct device *dev = watchdog_get_drvdata(wd);
> + dev_crit(dev, "error starting watchdog: %d\n", ret);
> + return -EIO;

I am quite sure sparse is going to complain about this ...
Why not just return ret ? This would result in a more detailed
error code/reason.

> + }
> +
> + return 0;
> +}
> +
> +static int wdt_ping(struct watchdog_device *wd)
> +{
> + int ret;
> +
> + ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
> + if (ret) {
> + struct device *dev = watchdog_get_drvdata(wd);
> + dev_crit(dev, "Error executing keepalive: 0x%x\n", ret);
> + return -EIO;

Same here.

> + }
> +
> + return 0;
> +}
> +
> +static int wdt_stop(struct watchdog_device *wd)
> +{
> + int ret;
> +
> + ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
> + if (ret) {
> + struct device *dev = watchdog_get_drvdata(wd);
> + dev_crit(dev, "Error stopping watchdog: 0x%x\n", ret);
> + return -EIO;

Same here.

> + }
> +
> + return 0;
> +}
> +
> +static irqreturn_t mid_wdt_warning_irq(int irq, void *dev_id)

This isn't really a warning, so the function name is a bit misleading.

> +{
> + panic("Kernel Watchdog");
> +
> + /* This code should not be reached */
> + return IRQ_HANDLED;
> +}
> +
> +static const struct watchdog_info mid_wdt_info = {
> + .identity = "Intel MID SCU watchdog",
> + .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
> +};
> +
> +static const struct watchdog_ops mid_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = wdt_start,
> + .stop = wdt_stop,
> + .ping = wdt_ping,
> +};
> +
> +static int mid_wdt_probe(struct platform_device *pdev)
> +{
> + struct watchdog_device *wdt_dev;
> + struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
> + int ret;
> +
> + if (!pdata) {
> + dev_err(&pdev->dev, "missing platform data\n");
> + return -EINVAL;
> + }
> +
> + if (pdata->probe) {
> + ret = pdata->probe();

Sure you don't want to pass the platform device as parameter ?
May not be needed today, but it might be better than to rely on the assumption
that the called code gets it from a static variable or structure (if needed).

This would enable you, for example, to use dev_warn() instead of pr_warn()
in the platform code.

> + if (ret)
> + return ret;
> + }
> +
> + wdt_dev = devm_kzalloc(&pdev->dev, sizeof(*wdt_dev), GFP_KERNEL);
> + if (!wdt_dev)
> + return -ENOMEM;
> +
> + wdt_dev->info = &mid_wdt_info;
> + wdt_dev->ops = &mid_wdt_ops;
> + wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
> + wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
> + wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
> +
> + watchdog_set_drvdata(wdt_dev, &pdev->dev);
> + platform_set_drvdata(pdev, wdt_dev);
> +
> + ret = devm_request_irq(&pdev->dev, pdata->irq, mid_wdt_warning_irq,
> + IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
> + wdt_dev);

If irq is mandatory, it might make sense to check if it is valid.

> + if (ret) {
> + dev_err(&pdev->dev, "error requesting warning irq %d\n",
> + pdata->irq);
> + return ret;
> + }
> +
> + ret = watchdog_register_device(wdt_dev);
> + if (ret) {
> + dev_err(&pdev->dev, "error registering watchdog device\n");
> + return ret;
> + }
> +
> + dev_info(&pdev->dev, "Intel MID watchdog device probed\n");
> +
> + return 0;
> +}
> +
> +static int mid_wdt_remove(struct platform_device *pdev)
> +{
> + struct watchdog_device *wd = platform_get_drvdata(pdev);
> + watchdog_unregister_device(wd);
> + return 0;
> +}
> +
> +static struct platform_driver mid_wdt_driver = {
> + .probe = mid_wdt_probe,
> + .remove = mid_wdt_remove,
> + .driver = {
> + .owner = THIS_MODULE,
> + .name = "intel_mid_wdt",
> + },
> +};
> +
> +module_platform_driver(mid_wdt_driver);
> +
> +MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
> +MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/intel-mid_wdt.h b/include/linux/intel-mid_wdt.h
> new file mode 100644
> index 000000000000..705dff1c62f8
> --- /dev/null
> +++ b/include/linux/intel-mid_wdt.h
> @@ -0,0 +1,20 @@
> +/*
> + * intel-mid_wdt: generic Intel MID SCU watchdog driver
> + *
> + * Copyright (C) 2014 Intel Corporation. All rights reserved.
> + * Contact: David Cohen <david.a.cohen@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General
> + * Public License as published by the Free Software Foundation.
> + */
> +
> +#ifndef __INTEL_MID_WDT_H__
> +#define __INTEL_MID_WDT_H__
> +
> +struct intel_mid_wdt_pdata {
> + int irq;
> + int (*probe)(void);
> +};
> +
> +#endif /*__INTEL_MID_WDT_H__*/
> --
> 1.9.1
>
> --
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