Re: [PATCH v3 2/2] Zodiac Aerospace RAVE Switch Watchdog Processor Driver

[Martyn Welch <martyn.welch@collabora.co.uk>]

On 25/11/15 14:52, Guenter Roeck wrote:
> Hi Martyn,
>
> On 11/25/2015 04:03 AM, Martyn Welch wrote:
>> This patch adds a driver for the Zodiac Aerospace RAVE Watchdog 
>> Procesor.
>> This device implements a watchdog timer, accessible over I2C.
>>
>> Cc: Guenter Roeck <linux@roeck-us.net>
>> Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
>> ---
>>
>> v2:
>>   - Improved error handling.
>>   - Correct indentation of split lines.
>>   - Remove unnecessary checks, casts and bracketing.
>>   - Remove sysfs entries provided by standard mechanisms.
>>   - Remove simple access functions.
>>   - Allocate wdd as a part of w_priv.
>>   - Add ability to set timeout from module parameter or device tree 
>> property
>>     rather than through a sysfs entry.
>>   - Add ability to set reset duration from module parameter or device 
>> tree
>>     property rather than through a sysfs entry.
>>
>> v3:
>>   - Correct naming of reset-duration-msec -> reset-duration-ms
>>   - Improved timeout logic (wasn't falling back to default, whoops.)
>>
>>   drivers/watchdog/Kconfig       |  11 ++
>>   drivers/watchdog/Makefile      |   1 +
>>   drivers/watchdog/ziirave_wdt.c | 428 
>> +++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 440 insertions(+)
>>   create mode 100644 drivers/watchdog/ziirave_wdt.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 7a8a6c6..816b5fb 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -161,6 +161,17 @@ config XILINX_WATCHDOG
>>         To compile this driver as a module, choose M here: the
>>         module will be called of_xilinx_wdt.
>>
>> +config ZIIRAVE_WATCHDOG
>> +    tristate "Zodiac RAVE Watchdog Timer"
>> +    depends on I2C
>> +    select WATCHDOG_CORE
>> +    help
>> +      Watchdog driver for the Zodiac Aerospace RAVE Switch Watchdog
>> +      Processor.
>> +
>> +      To compile this driver as a module, choose M here: the
>> +      module will be called ziirave_wdt.
>> +
>>   # ALPHA Architecture
>>
>>   # ARM Architecture
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 53d4827..05ba23a 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -190,5 +190,6 @@ obj-$(CONFIG_GPIO_WATCHDOG)    += gpio_wdt.o
>>   obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>>   obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
>>   obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
>> +obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
>>   obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
>>   obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
>> diff --git a/drivers/watchdog/ziirave_wdt.c 
>> b/drivers/watchdog/ziirave_wdt.c
>> new file mode 100644
>> index 0000000..3d337ab
>> --- /dev/null
>> +++ b/drivers/watchdog/ziirave_wdt.c
>> @@ -0,0 +1,428 @@
>> +/*
>> + * Copyright (C) 2015 Zodiac Inflight Innovations
>> + *
>> + * Author: Martyn Welch <martyn.welch@collabora.co.uk>
>> + *
>> + * Based on twl4030_wdt.c by Timo Kokkonen <timo.t.kokkonen at 
>> nokia.com>:
>> + *
>> + * Copyright (C) Nokia Corporation
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/types.h>
>> +#include <linux/slab.h>
>> +#include <linux/kernel.h>
>> +#include <linux/watchdog.h>
>> +#include <linux/i2c.h>
>> +#include <linux/version.h>
>> +#include <linux/sysfs.h>
>> +
>> +#define ZIIRAVE_TIMEOUT_MIN    3
>> +#define ZIIRAVE_TIMEOUT_DEFAULT    30
>> +#define ZIIRAVE_TIMEOUT_MAX    255
>> +
>> +#define ZIIRAVE_PING_VALUE    0x0
>> +#define ZIIRAVE_RESET_VALUE    0x1
>> +
>> +#define ZIIRAVE_STATE_INITIAL    0x0
>> +#define ZIIRAVE_STATE_OFF    0x1
>> +#define ZIIRAVE_STATE_ON    0x2
>> +#define ZIIRAVE_STATE_TRIGGERED    0x3
>> +
>> +static char *ziirave_states[] = {"unconfigured", "disabled", "enabled",
>> +                 "triggered"};
>> +
>> +#define ZIIRAVE_REASON_POWER_UP    0x0
>> +#define ZIIRAVE_REASON_HW_WDT    0x1
>> +#define ZIIRAVE_REASON_HOST_REQ    0x4
>> +#define ZIIRAVE_REASON_IGL_CFG    0x6
>> +#define ZIIRAVE_REASON_IGL_INST    0x7
>> +#define ZIIRAVE_REASON_IGL_TRAP    0x8
>> +#define ZIIRAVE_REASON_UNKNOWN    0x9
>> +
>> +static char *ziirave_reasons[] = {"power cycle", "triggered", "host 
>> request",
>> +                  "illegal configuration",
>> +                  "illegal instruction", "illegal trap",
>> +                  "unknown"};
>> +
>
> I don't see mapping code from the reason values to the array.
> "host request" is array index 2 but the defined value is 0x4.
>
> Am I missing something ?
>

Whoops, missed that. I guess the simplest thing to do is pad out the array?

>> +#define ZIIRAVE_WDT_FIRM_VER_MAJOR    0x1
>> +#define ZIIRAVE_WDT_FIRM_VER_MINOR    0x2
>> +#define ZIIRAVE_WDT_BOOT_VER_MAJOR    0x3
>> +#define ZIIRAVE_WDT_BOOT_VER_MINOR    0x4
>> +#define ZIIRAVE_WDT_RESET_REASON    0x5
>> +#define ZIIRAVE_WDT_STATE        0x6
>> +#define ZIIRAVE_WDT_TIMEOUT        0x7
>> +#define ZIIRAVE_WDT_TIME_LEFT        0x8
>> +#define ZIIRAVE_WDT_PING        0x9
>> +#define ZIIRAVE_WDT_RESET_DURATION    0xa
>> +#define ZIIRAVE_WDT_RESET_WDT        0xb
>> +#define ZIIRAVE_WDT_GOTO_BOOTLOADER    0xc
>> +#define ZIIRAVE_WDT_FORCE_RESET_HOST    0xd
>> +
>
> Do you plan to use the unused defines in a later patch ?
>

No, will remove.

>> +struct ziirave_wdt_rev {
>> +    unsigned char part;
>> +    unsigned char major;
>> +    unsigned char minor;
>> +};
>> +
>> +struct ziirave_wdt_data {
>> +    struct watchdog_device wdd;
>> +    struct ziirave_wdt_rev bootloader_rev;
>> +    struct ziirave_wdt_rev firmware_rev;
>> +    int reset_reason;
>> +};
>> +
>> +static int wdt_timeout;
>> +module_param(wdt_timeout, int, 0);
>> +MODULE_PARM_DESC(wdt_timeout, "Watchdog timeout in seconds");
>> +
>> +static int reset_duration;
>> +module_param(reset_duration, int, 0);
>> +MODULE_PARM_DESC(reset_duration,
>> +         "Watchdog reset pulse duration in milliseconds");
>> +
>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> +module_param(nowayout, bool, 0);
>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started 
>> default="
>> +         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> +
>> +static int ziirave_wdt_firmware_rev(struct i2c_client *client,
>> +                    struct ziirave_wdt_rev *rev)
>> +{
>> +    int ret;
>> +
>> +    rev->part = 2;
>> +    ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_FIRM_VER_MAJOR);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    rev->major = ret;
>> +
>> +    ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_FIRM_VER_MINOR);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    rev->minor = ret;
>> +
>> +    return 0;
>> +}
>> +
>> +static int ziirave_wdt_bootloader_rev(struct i2c_client *client,
>> +                      struct ziirave_wdt_rev *rev)
>> +{
>> +    int ret;
>> +
>> +    rev->part = 1;
>> +    ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_BOOT_VER_MAJOR);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    rev->major = ret;
>> +
>> +    ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_BOOT_VER_MINOR);
>> +
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    rev->minor = ret;
>> +
>> +    return 0;
>> +}
>
> You could merge those two functions into one by also specifying
> the registers as parameters. 'part' does not really provide any value -
> you could hard-code it in the print function.
>

Ok.

>> +
>> +static int ziirave_wdt_set_state(struct watchdog_device *wdd, int 
>> state)
>> +{
>> +    struct i2c_client *client = to_i2c_client(wdd->parent);
>> +
>> +    return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_STATE, state);
>> +}
>> +
>> +static int ziirave_wdt_start(struct watchdog_device *wdd)
>> +{
>> +    return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_ON);
>> +}
>> +
>> +static int ziirave_wdt_stop(struct watchdog_device *wdd)
>> +{
>> +    return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_OFF);
>> +}
>> +
>> +static int ziirave_wdt_ping(struct watchdog_device *wdd)
>> +{
>> +    struct i2c_client *client = to_i2c_client(wdd->parent);
>> +
>> +    return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_PING,
>> +                     ZIIRAVE_PING_VALUE);
>> +}
>> +
>> +static int ziirave_wdt_set_timeout(struct watchdog_device *wdd,
>> +                   unsigned int timeout)
>> +{
>> +    struct i2c_client *client = to_i2c_client(wdd->parent);
>> +    int ret;
>> +
>> +    ret = i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_TIMEOUT,
>> +                    timeout);
>> +    if (!ret)
>> +        wdd->timeout = timeout;
>> +
>> +    return ret;
>> +}
>> +
>> +static unsigned int ziirave_wdt_get_timeleft(struct watchdog_device 
>> *wdd)
>> +{
>> +    struct i2c_client *client = to_i2c_client(wdd->parent);
>> +    int ret;
>> +
>> +    ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIME_LEFT);
>> +    if (ret < 0)
>> +        ret = 0;
>> +
>> +    return ret;
>> +}
>> +
>> +static const struct watchdog_info ziirave_wdt_info = {
>> +    .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 
>> WDIOF_KEEPALIVEPING,
>> +    .identity = "Zodiac RAVE Watchdog",
>> +};
>> +
>> +static const struct watchdog_ops ziirave_wdt_ops = {
>> +    .owner        = THIS_MODULE,
>> +    .start        = ziirave_wdt_start,
>> +    .stop        = ziirave_wdt_stop,
>> +    .ping        = ziirave_wdt_ping,
>> +    .set_timeout    = ziirave_wdt_set_timeout,
>> +    .get_timeleft    = ziirave_wdt_get_timeleft,
>> +};
>> +
>> +static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,
>> +                       struct device_attribute *attr,
>> +                       char *buf)
>> +{
>> +    struct i2c_client *client = to_i2c_client(dev->parent);
>> +    struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
>> +
>> +    return sprintf(buf, "%02u.%02u.%02u", w_priv->firmware_rev.part,
>> +               w_priv->firmware_rev.major, w_priv->firmware_rev.minor);
>> +}
>> +
>> +static DEVICE_ATTR(firmware_version, S_IRUGO, 
>> ziirave_wdt_sysfs_show_firm,
>> +           NULL);
>> +
>> +static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,
>> +                       struct device_attribute *attr,
>> +                       char *buf)
>> +{
>> +    struct i2c_client *client = to_i2c_client(dev->parent);
>> +    struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
>> +
>> +    return sprintf(buf, "%02u.%02u.%02u", w_priv->bootloader_rev.part,
>> +               w_priv->bootloader_rev.major,
>> +               w_priv->bootloader_rev.minor);
>> +}
>> +
>> +static DEVICE_ATTR(bootloader_version, S_IRUGO, 
>> ziirave_wdt_sysfs_show_boot,
>> +           NULL);
>> +
>> +static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,
>> +                         struct device_attribute *attr,
>> +                         char *buf)
>> +{
>> +    struct i2c_client *client = to_i2c_client(dev->parent);
>> +    struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
>> +
>> +    if (w_priv->reset_reason < 0 ||
>> +        w_priv->reset_reason >= ARRAY_SIZE(ziirave_states))
>> +        return sprintf(buf, "error");
>> +
> The probe function bails out on error, and if the reason is out of range,
> so this range check is unnecessary.
>

Ok.

>> +    return sprintf(buf, "%s", ziirave_reasons[w_priv->reset_reason]);
>> +}
>> +
>> +static DEVICE_ATTR(reset_reason, S_IRUGO, 
>> ziirave_wdt_sysfs_show_reason,
>> +           NULL);
>> +
>> +static struct attribute *ziirave_wdt_attrs[] = {
>> +    &dev_attr_firmware_version.attr,
>> +    &dev_attr_bootloader_version.attr,
>> +    &dev_attr_reset_reason.attr,
>> +    NULL
>> +};
>> +
>> +static const struct attribute_group ziirave_wdt_sysfs_files = {
>> +    .attrs  = ziirave_wdt_attrs,
>> +};
>> +
>> +static int ziirave_wdt_init_duration(struct i2c_client *client,
>> +                     int duration_parm)
>> +{
>> +    int duration = 0;
>> +    int ret = 0;
>
> Unnecessary initialization.
>

Ok.

>> +
>> +    if (duration_parm) {
>> +        duration = duration_parm;
>> +    } else {
>
> Since you are initializing duration, you might as well use it directly as
> parameter.
>
>     ..., int duration)
> {
>     ..
>     if (!duration) {
>

Good point.

>> +        /* See if the reset pulse duration is provided in an of_node */
>> +        if (client->dev.of_node == NULL)
>> +            return ret;
>> +
>> +        ret = of_property_read_u32(client->dev.of_node,
>> +                       "reset-duration-ms", &duration);
>> +        if (ret)
>> +            return ret;
>> +    }
>> +
>> +    if (duration < 1 || duration > 255)
>> +        return -EINVAL;
>> +
>> +    dev_info(&client->dev, "Setting reset duration to %dms", duration);
>> +
>> +    ret = i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_RESET_DURATION,
>> +                    duration);
>> +
>> +    return ret;
>> +}
>> +
>> +static int ziirave_wdt_probe(struct i2c_client *client,
>> +                 const struct i2c_device_id *id)
>> +{
>> +    int ret;
>> +    struct ziirave_wdt_data *w_priv;
>> +    int val;
>> +
>> +    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
>> +                     | I2C_FUNC_SMBUS_BYTE_DATA
>> +                     | I2C_FUNC_SMBUS_READ_I2C_BLOCK))
>
> Why 2C_FUNC_SMBUS_READ_I2C_BLOCK, and why I2C_FUNC_I2C ?
> Unless I am missing something, you only need I2C_FUNC_SMBUS_BYTE_DATA.
>

Left over from some early goes at implementing it and hadn't noticed it 
again to take it out.

>> +        return -ENODEV;
>> +
>> +    w_priv = devm_kzalloc(&client->dev, sizeof(*w_priv), GFP_KERNEL);
>> +    if (!w_priv)
>> +        return -ENOMEM;
>> +
>> +    w_priv->wdd.info = &ziirave_wdt_info;
>> +    w_priv->wdd.ops = &ziirave_wdt_ops;
>> +    w_priv->wdd.status = 0;
>
> Unnecessary initialization.
>

Ok.

>> +    w_priv->wdd.min_timeout = ZIIRAVE_TIMEOUT_MIN;
>> +    w_priv->wdd.max_timeout = ZIIRAVE_TIMEOUT_MAX;
>> +    w_priv->wdd.parent = &client->dev;
>> +
>> +    ret = watchdog_init_timeout(&w_priv->wdd, wdt_timeout, 
>> &client->dev);
>> +    if (ret) {
>> +        dev_info(&client->dev,
>> +             "Unable to select timeout value, using default\n");
>> +    }
>> +
>> +    /*
>> +     * The default value set in the watchdog should be perfectly 
>> valid, so
>> +     * pass that in if we haven't provided one via the module 
>> parameter or
>> +     * of property.
>> +     */
>> +    if (w_priv->wdd.timeout == 0) {
>> +        val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIMEOUT);
>> +        if (val < 0)
>> +            return val;
>> +
>> +        w_priv->wdd.timeout = val;
>
> What if the returned value is 0 ?
>

Minimum timeout is 3, device won't accept a value below that and should 
never return a value
below that.

>> +    } else {
>> +        ret = ziirave_wdt_set_timeout(&w_priv->wdd, 
>> w_priv->wdd.timeout);
>> +        if (ret)
>> +            return ret;
>> +
>> +        dev_info(&client->dev, "Timeout set to %ds.", 
>> w_priv->wdd.timeout);
>> +    }
>> +
>> +    watchdog_set_nowayout(&w_priv->wdd, nowayout);
>> +
>> +    i2c_set_clientdata(client, w_priv);
>> +
>> +    /* If in unconfigured state, set to stopped */
>> +    val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_STATE);
>> +    if (val < 0)
>> +        return val;
>> +
>> +    if (val == ZIIRAVE_STATE_INITIAL)
>> +        ziirave_wdt_stop(&w_priv->wdd);
>> +
>> +    ret = watchdog_register_device(&w_priv->wdd);
>> +    if (ret)
>> +        return ret;
>> +
>> +    ret = ziirave_wdt_init_duration(client, reset_duration);
>> +    if (ret) {
>> +        dev_info(&client->dev,
>> +             "Unable to set reset pulse duration, using default\n");
>> +    }
>> +
>> +    ret = ziirave_wdt_firmware_rev(client, &w_priv->firmware_rev);
>> +    if (ret)
>> +        goto err;
>> +
>> +    ret = ziirave_wdt_bootloader_rev(client, &w_priv->bootloader_rev);
>> +    if (ret)
>> +        goto err;
>> +
>> +    w_priv->reset_reason = i2c_smbus_read_byte_data(client,
>> +                        ZIIRAVE_WDT_RESET_REASON);
>> +    if (w_priv->reset_reason < 0
>> +        || w_priv->reset_reason >= ARRAY_SIZE(ziirave_reasons))
>> +        goto err;
>> +
> Would it make sense to call those functions prior to registering the 
> watchdog ?
> This would simplify error handling, and avoid a registration followed 
> by an
> unregistration if the i2c functions return an error.
>

Ah, yes - the helper functions I was using took wdd, so the device 
needed to be register for them to work. Not the case any more so this 
can be done prior to registration.

>> +    ret = sysfs_create_group(&w_priv->wdd.dev->kobj,
>> +                 &ziirave_wdt_sysfs_files);
>> +    if (ret)
>> +        goto err;
>> +
>> +    return 0;
>> +err:
>> +    watchdog_unregister_device(&w_priv->wdd);
>> +
>> +    return ret;
>> +}
>> +
>> +static int ziirave_wdt_remove(struct i2c_client *client)
>> +{
>> +    struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
>> +
>> +    sysfs_remove_group(&client->dev.kobj, &ziirave_wdt_sysfs_files);
>> +
>> +    watchdog_unregister_device(&w_priv->wdd);
>> +
>> +    return 0;
>> +}
>> +
>> +static struct i2c_device_id ziirave_wdt_id[] = {
>> +    { "ziirave-wdt", 0 },
>> +    { }
>> +};
>> +MODULE_DEVICE_TABLE(i2c, ziirave_wdt_id);
>> +
>> +static const struct of_device_id zrv_wdt_of_match[] = {
>> +    { .compatible = "zii,rave-wdt", },
>> +    { },
>> +};
>> +MODULE_DEVICE_TABLE(of, zrv_wdt_of_match);
>> +
>> +static struct i2c_driver ziirave_wdt_driver = {
>> +    .driver = {
>> +        .name = "ziirave_wdt",
>> +        .of_match_table = zrv_wdt_of_match,
>> +    },
>> +    .probe = ziirave_wdt_probe,
>> +    .remove = ziirave_wdt_remove,
>> +    .id_table = ziirave_wdt_id,
>> +};
>> +
>> +module_i2c_driver(ziirave_wdt_driver);
>> +
>> +MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk");
>> +MODULE_DESCRIPTION("Zodiac Aerospace RAVE Switch Watchdog Processor 
>> Driver");
>> +MODULE_LICENSE("GPL");
>> +
>>
>