diff mbox

[RFC,1/3] watchdog: Add Meson GXBB Watchdog Driver

Message ID 1464249112-13658-2-git-send-email-narmstrong@baylibre.com (mailing list archive)
State New, archived
Headers show

Commit Message

Neil Armstrong May 26, 2016, 7:51 a.m. UTC 
Add watchdog specific driver for Amlogic Meson GXBB SoC.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/watchdog/Makefile         |   1 +
 drivers/watchdog/meson_gxbb_wdt.c | 287 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 288 insertions(+)
 create mode 100644 drivers/watchdog/meson_gxbb_wdt.c

Comments

Carlo Caione May 26, 2016, 10:06 a.m. UTC | #1 
On 26/05/16 09:51, Neil Armstrong wrote:
> Add watchdog specific driver for Amlogic Meson GXBB SoC.
> 
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> +

[...]
> +#define DEFAULT_TIMEOUT	10	/* seconds */
> +
> +#define GXBB_WDT_CTRL_REG	0x0
> +#define GXBB_WDT_CTRL1_REG	0x4
> +#define GXBB_WDT_TCNT_REG	0x8
> +#define GXBB_WDT_RSET_REG	0xc
> +
> +#define GXBB_WDT_CTRL_EE_RESET_NOW	BIT(26)
> +
> +#define GXBB_WDT_CTRL_CLKDIV_EN	BIT(25)
> +#define GXBB_WDT_CTRL_CLK_EN	BIT(24)
> +#define GXBB_WDT_CTRL_IRQ_EN	BIT(23)
> +#define GXBB_WDT_CTRL_EE_RESET	BIT(21)
> +#define GXBB_WDT_CTRL_XTAL_SEL	(0)
> +#define GXBB_WDT_CTRL_CLK81_SEL	BIT(19)
> +#define GXBB_WDT_CTRL_EN	BIT(18)
> +#define GXBB_WDT_CTRL_DIV_MASK	(BIT(18)-1)
> +
> +#define GXBB_WDT_CTRL1_GPIO_PULSE	BIT(17)
> +#define GXBB_WDT_CTRL1_GPIO_POL_RESET_0	BIT(16)
> +#define GXBB_WDT_CTRL1_GPIO_POL_RESET_1	(0)
> +#define GXBB_WDT_CTRL1_GPIO_PULSE_CNT	(BIT(16)-1)
> +
> +#define GXBB_WDT_TCNT_SETUP_MASK	(BIT(16)-1)
> +#define GXBB_WDT_TCNT_CNT_SHIFT		16

Indentation

[...]
> +int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
> +			       unsigned int timeout)
> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	if (watchdog_active(wdt_dev))
> +		meson_gxbb_wdt_stop(wdt_dev);
> +
> +	meson_gxbb_wdt_ping(wdt_dev);
> +
> +	writel(timeout*1000, data->reg_base + GXBB_WDT_TCNT_REG);

nit: spaces around "*"

[...]
> +	data->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(data->clk))
> +		return PTR_ERR(data->clk);
> +
> +	clk_prepare_enable(data->clk);

Do we need to merge the clock controller driver before this?

Cheers,
Guenter Roeck May 26, 2016, 1:54 p.m. UTC | #2 
On 05/26/2016 12:51 AM, Neil Armstrong wrote:
> Add watchdog specific driver for Amlogic Meson GXBB SoC.
>

Wondering - why RFC ?

> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>   drivers/watchdog/Makefile         |   1 +
>   drivers/watchdog/meson_gxbb_wdt.c | 287 ++++++++++++++++++++++++++++++++++++++
>   2 files changed, 288 insertions(+)
>   create mode 100644 drivers/watchdog/meson_gxbb_wdt.c
>
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 9bde095..7679d93 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -68,6 +68,7 @@ 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_WATCHDOG) += meson_wdt.o
> +obj-$(CONFIG_MESON_WATCHDOG) += meson_gxbb_wdt.o
>   obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
>   obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
>   obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
> diff --git a/drivers/watchdog/meson_gxbb_wdt.c b/drivers/watchdog/meson_gxbb_wdt.c
> new file mode 100644
> index 0000000..0c7c0d9
> --- /dev/null
> +++ b/drivers/watchdog/meson_gxbb_wdt.c
> @@ -0,0 +1,287 @@
> +/*
> + * This file is provided under a dual BSD/GPLv2 license.  When using or
> + * redistributing this file, you may do so under either license.
> + *
> + * GPL LICENSE SUMMARY
> + *
> + * Copyright (c) 2016 BayLibre, SAS.
> + * Author: Neil Armstrong <narmstrong@baylibre.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.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, see <http://www.gnu.org/licenses/>.
> + * The full GNU General Public License is included in this distribution
> + * in the file called COPYING.
> + *
> + * BSD LICENSE
> + *
> + * Copyright (c) 2016 BayLibre, SAS.
> + * Author: Neil Armstrong <narmstrong@baylibre.com>
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + *
> + *   * Redistributions of source code must retain the above copyright
> + *     notice, this list of conditions and the following disclaimer.
> + *   * Redistributions in binary form must reproduce the above copyright
> + *     notice, this list of conditions and the following disclaimer in
> + *     the documentation and/or other materials provided with the
> + *     distribution.
> + *   * Neither the name of Intel Corporation nor the names of its
> + *     contributors may be used to endorse or promote products derived
> + *     from this software without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
> + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
> + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/clk.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/watchdog.h>
> +
> +#define DEFAULT_TIMEOUT	10	/* seconds */
> +
> +#define GXBB_WDT_CTRL_REG	0x0
> +#define GXBB_WDT_CTRL1_REG	0x4
> +#define GXBB_WDT_TCNT_REG	0x8
> +#define GXBB_WDT_RSET_REG	0xc
> +
> +#define GXBB_WDT_CTRL_EE_RESET_NOW	BIT(26)
> +
> +#define GXBB_WDT_CTRL_CLKDIV_EN	BIT(25)
> +#define GXBB_WDT_CTRL_CLK_EN	BIT(24)
> +#define GXBB_WDT_CTRL_IRQ_EN	BIT(23)
> +#define GXBB_WDT_CTRL_EE_RESET	BIT(21)
> +#define GXBB_WDT_CTRL_XTAL_SEL	(0)
> +#define GXBB_WDT_CTRL_CLK81_SEL	BIT(19)
> +#define GXBB_WDT_CTRL_EN	BIT(18)
> +#define GXBB_WDT_CTRL_DIV_MASK	(BIT(18)-1)
> +
> +#define GXBB_WDT_CTRL1_GPIO_PULSE	BIT(17)
> +#define GXBB_WDT_CTRL1_GPIO_POL_RESET_0	BIT(16)
> +#define GXBB_WDT_CTRL1_GPIO_POL_RESET_1	(0)
> +#define GXBB_WDT_CTRL1_GPIO_PULSE_CNT	(BIT(16)-1)
> +

Spaces around operators, please.

> +#define GXBB_WDT_TCNT_SETUP_MASK	(BIT(16)-1)
> +#define GXBB_WDT_TCNT_CNT_SHIFT		16
> +
> +struct meson_gxbb_wdt {
> +	void __iomem *reg_base;
> +	struct watchdog_device wdt_dev;
> +	struct clk *clk;
> +};
> +
> +int meson_gxbb_wdt_start(struct watchdog_device *wdt_dev)

Functions should all be static.

> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) | GXBB_WDT_CTRL_EN,
> +		data->reg_base + GXBB_WDT_CTRL_REG);
> +
> +	return 0;
> +}
> +
> +int meson_gxbb_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) & ~GXBB_WDT_CTRL_EN,
> +		data->reg_base + GXBB_WDT_CTRL_REG);
> +
> +	return 0;
> +}
> +
> +unsigned int meson_gxbb_wdt_status(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	return !!(readl(data->reg_base + GXBB_WDT_CTRL_REG) & GXBB_WDT_CTRL_EN);

This function is not supposed to return 0/1 but a bit mask with relevant
WDIOF_bits set. sbsa_gwdt.c is buggy (oops, and I reviewed it ;-), so
please don't use it as example; it doesn't make much sense to return
a kernel-only flag to user space.

Overall I would suggest to not implement the function at all. We'll have
to revisit it - its current implementation in the watchdog core does not
make much sense and for the most part only returns 0 to user space.
The only driver implementing it (sbsa) returns a bad value. It is also
_not_ supposed to return the "watchdog running" status as currently
implemented (there is no WDIOF_ flag indicating that the watchdog is
running).

> +}
> +
> +int meson_gxbb_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	writel(0, data->reg_base + GXBB_WDT_RSET_REG);
> +
> +	return 0;
> +}
> +
> +int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
> +			       unsigned int timeout)
> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	if (watchdog_active(wdt_dev))
> +		meson_gxbb_wdt_stop(wdt_dev);
> +

Is the stop/start sequence mandatory ? It leaves the system unprotected
for a few cycles, so it is undesirable.

> +	meson_gxbb_wdt_ping(wdt_dev);
> +
> +	writel(timeout*1000, data->reg_base + GXBB_WDT_TCNT_REG);
> +
> +	if (watchdog_active(wdt_dev))
> +		meson_gxbb_wdt_start(wdt_dev);
> +
> +	return 0;
> +}
> +
> +unsigned int meson_gxbb_wdt_get_timeleft(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
> +	unsigned long reg;
> +
> +	reg = readl(data->reg_base + GXBB_WDT_TCNT_REG);
> +
> +	return ((reg >> GXBB_WDT_TCNT_CNT_SHIFT)-
> +			(reg & GXBB_WDT_TCNT_SETUP_MASK)) / 1000;
> +}
> +
> +static const struct watchdog_ops meson_gxbb_wdt_ops = {
> +	.start = meson_gxbb_wdt_start,
> +	.stop = meson_gxbb_wdt_stop,
> +	.status = meson_gxbb_wdt_status,
> +	.ping = meson_gxbb_wdt_ping,
> +	.set_timeout = meson_gxbb_wdt_set_timeout,
> +	.get_timeleft = meson_gxbb_wdt_get_timeleft,
> +};
> +
> +static const struct watchdog_info meson_gxbb_wdt_info = {
> +	.identity = "meson-gxbb-wdt",
> +	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> +};
> +
> +static int __maybe_unused meson_gxbb_wdt_resume(struct device *dev)
> +{
> +	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
> +
> +	if (watchdog_active(&data->wdt_dev))
> +		meson_gxbb_wdt_start(&data->wdt_dev);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused meson_gxbb_wdt_suspend(struct device *dev)
> +{
> +	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
> +
> +	if (watchdog_active(&data->wdt_dev))
> +		meson_gxbb_wdt_stop(&data->wdt_dev);
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops meson_gxbb_wdt_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(meson_gxbb_wdt_suspend, meson_gxbb_wdt_resume)
> +};
> +
> +static const struct of_device_id meson_gxbb_wdt_dt_ids[] = {
> +	 { .compatible = "amlogic,meson-gxbb-wdt", },
> +	 { /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, meson_gxbb_wdt_dt_ids);
> +
> +static int meson_gxbb_wdt_probe(struct platform_device *pdev)
> +{
> +	struct meson_gxbb_wdt *data;
> +	struct resource *res;
> +	int ret;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	data->reg_base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(data->reg_base))
> +		return PTR_ERR(data->reg_base);
> +
> +	data->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(data->clk))
> +		return PTR_ERR(data->clk);
> +
> +	clk_prepare_enable(data->clk);
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	data->wdt_dev.parent = &pdev->dev;
> +	data->wdt_dev.info = &meson_gxbb_wdt_info;
> +	data->wdt_dev.ops = &meson_gxbb_wdt_ops;
> +	data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
> +	data->wdt_dev.min_hw_heartbeat_ms = 1;

Does the device require a minimum time between heartbeats ?
Just asking, because you violate it yourself below.

If you want to set the minimum timeout, that would be min_timeout.

> +	data->wdt_dev.timeout = DEFAULT_TIMEOUT;
> +	watchdog_set_drvdata(&data->wdt_dev, data);
> +
> +	watchdog_init_timeout(&data->wdt_dev, DEFAULT_TIMEOUT, &pdev->dev);
> +

DEFAULT_TIMEOUT is unnecessary here. Since the default timeout is already set,
it makes the call useless.

> +	ret = watchdog_register_device(&data->wdt_dev);
> +	if (ret)
> +		return ret;
> +
> +	/* Setup with 1ms timebase */
> +	writel(((clk_get_rate(data->clk) / 1000) & GXBB_WDT_CTRL_DIV_MASK) |
> +		GXBB_WDT_CTRL_EE_RESET |
> +		GXBB_WDT_CTRL_CLK_EN |
> +		GXBB_WDT_CTRL_CLKDIV_EN,
> +		data->reg_base + GXBB_WDT_CTRL_REG);
> +	meson_gxbb_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);

set_timeout already calls the ping function. Also, the functions should be called
prior to watchdog registration to avoid race conditions.

> +	meson_gxbb_wdt_ping(&data->wdt_dev);

This is unusual. If the watchdog can be already running, it might make sense
to tell the core about it (set WDOG_HW_RUNNING in the status field), so it
can send heartbeats until user space opens the device.

> +
> +	return 0;
> +}
> +
> +static int meson_gxbb_wdt_remove(struct platform_device *pdev)
> +{
> +	struct meson_gxbb_wdt *data = platform_get_drvdata(pdev);
> +
> +	watchdog_unregister_device(&data->wdt_dev);
> +
> +	return 0;
> +}
> +
> +static void meson_gxbb_wdt_shutdown(struct platform_device *pdev)
> +{
> +	struct meson_gxbb_wdt *data = platform_get_drvdata(pdev);
> +
> +	meson_gxbb_wdt_stop(&data->wdt_dev);
> +}
> +
> +static struct platform_driver meson_gxbb_wdt_driver = {
> +	.probe	= meson_gxbb_wdt_probe,
> +	.remove	= meson_gxbb_wdt_remove,
> +	.shutdown = meson_gxbb_wdt_shutdown,
> +	.driver = {
> +		.name = "meson-gxbb-wdt",
> +		.pm = &meson_gxbb_wdt_pm_ops,
> +		.of_match_table	= meson_gxbb_wdt_dt_ids,
> +	},
> +};
> +
> +module_platform_driver(meson_gxbb_wdt_driver);
> +
> +MODULE_ALIAS("platform:meson-gxbb-wdt");
> +MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
> +MODULE_DESCRIPTION("Amlogic Meson GXBB Watchdog timer driver");
> +MODULE_LICENSE("Dual BSD/GPL");
>
Neil Armstrong May 27, 2016, 8:22 a.m. UTC | #3 
On 05/26/2016 12:06 PM, Carlo Caione wrote:
> On 26/05/16 09:51, Neil Armstrong wrote:
>> Add watchdog specific driver for Amlogic Meson GXBB SoC.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> +
> 
> [...]
>> +#define DEFAULT_TIMEOUT	10	/* seconds */
>> +
>> +#define GXBB_WDT_CTRL_REG	0x0
>> +#define GXBB_WDT_CTRL1_REG	0x4
>> +#define GXBB_WDT_TCNT_REG	0x8
>> +#define GXBB_WDT_RSET_REG	0xc
>> +
>> +#define GXBB_WDT_CTRL_EE_RESET_NOW	BIT(26)
>> +
>> +#define GXBB_WDT_CTRL_CLKDIV_EN	BIT(25)
>> +#define GXBB_WDT_CTRL_CLK_EN	BIT(24)
>> +#define GXBB_WDT_CTRL_IRQ_EN	BIT(23)
>> +#define GXBB_WDT_CTRL_EE_RESET	BIT(21)
>> +#define GXBB_WDT_CTRL_XTAL_SEL	(0)
>> +#define GXBB_WDT_CTRL_CLK81_SEL	BIT(19)
>> +#define GXBB_WDT_CTRL_EN	BIT(18)
>> +#define GXBB_WDT_CTRL_DIV_MASK	(BIT(18)-1)
>> +
>> +#define GXBB_WDT_CTRL1_GPIO_PULSE	BIT(17)
>> +#define GXBB_WDT_CTRL1_GPIO_POL_RESET_0	BIT(16)
>> +#define GXBB_WDT_CTRL1_GPIO_POL_RESET_1	(0)
>> +#define GXBB_WDT_CTRL1_GPIO_PULSE_CNT	(BIT(16)-1)
>> +
>> +#define GXBB_WDT_TCNT_SETUP_MASK	(BIT(16)-1)
>> +#define GXBB_WDT_TCNT_CNT_SHIFT		16
> 
> Indentation
> 
> [...]
>> +int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
>> +			       unsigned int timeout)
>> +{
>> +	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +	if (watchdog_active(wdt_dev))
>> +		meson_gxbb_wdt_stop(wdt_dev);
>> +
>> +	meson_gxbb_wdt_ping(wdt_dev);
>> +
>> +	writel(timeout*1000, data->reg_base + GXBB_WDT_TCNT_REG);
> 
> nit: spaces around "*"
> 
> [...]
>> +	data->clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (IS_ERR(data->clk))
>> +		return PTR_ERR(data->clk);
>> +
>> +	clk_prepare_enable(data->clk);
> 
> Do we need to merge the clock controller driver before this?

It's not necessary, currently it only selects the xtal source, so it's works with the current upstream architecture.

Neil

> 
> Cheers,
>
Neil Armstrong May 27, 2016, 8:25 a.m. UTC | #4 
On 05/26/2016 03:54 PM, Guenter Roeck wrote:
> On 05/26/2016 12:51 AM, Neil Armstrong wrote:
>> Add watchdog specific driver for Amlogic Meson GXBB SoC.
>>
> 
> Wondering - why RFC ?

For these precious comments !
Thanks Guenter.

> 
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>   drivers/watchdog/Makefile         |   1 +
>>   drivers/watchdog/meson_gxbb_wdt.c | 287 ++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 288 insertions(+)
>>   create mode 100644 drivers/watchdog/meson_gxbb_wdt.c
>>
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 9bde095..7679d93 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile

[...]

>> +
>> +unsigned int meson_gxbb_wdt_status(struct watchdog_device *wdt_dev)
>> +{
>> +    struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    return !!(readl(data->reg_base + GXBB_WDT_CTRL_REG) & GXBB_WDT_CTRL_EN);
> 
> This function is not supposed to return 0/1 but a bit mask with relevant
> WDIOF_bits set. sbsa_gwdt.c is buggy (oops, and I reviewed it ;-), so
> please don't use it as example; it doesn't make much sense to return
> a kernel-only flag to user space.
> 
> Overall I would suggest to not implement the function at all. We'll have
> to revisit it - its current implementation in the watchdog core does not
> make much sense and for the most part only returns 0 to user space.
> The only driver implementing it (sbsa) returns a bad value. It is also
> _not_ supposed to return the "watchdog running" status as currently
> implemented (there is no WDIOF_ flag indicating that the watchdog is
> running).

Ok, will remove it.

>> +}
>> +
>> +int meson_gxbb_wdt_ping(struct watchdog_device *wdt_dev)
>> +{
>> +    struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    writel(0, data->reg_base + GXBB_WDT_RSET_REG);
>> +
>> +    return 0;
>> +}
>> +
>> +int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
>> +                   unsigned int timeout)
>> +{
>> +    struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    if (watchdog_active(wdt_dev))
>> +        meson_gxbb_wdt_stop(wdt_dev);
>> +
> 
> Is the stop/start sequence mandatory ? It leaves the system unprotected
> for a few cycles, so it is undesirable.

No, it's not mandatory, it's a good point.

>> +
>> +    data->wdt_dev.parent = &pdev->dev;
>> +    data->wdt_dev.info = &meson_gxbb_wdt_info;
>> +    data->wdt_dev.ops = &meson_gxbb_wdt_ops;
>> +    data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
>> +    data->wdt_dev.min_hw_heartbeat_ms = 1;
> 
> Does the device require a minimum time between heartbeats ?
> Just asking, because you violate it yourself below.
> 
> If you want to set the minimum timeout, that would be min_timeout.

Ok, these values are not very clear actually.

>> +    data->wdt_dev.timeout = DEFAULT_TIMEOUT;
>> +    watchdog_set_drvdata(&data->wdt_dev, data);
>> +
>> +    watchdog_init_timeout(&data->wdt_dev, DEFAULT_TIMEOUT, &pdev->dev);
>> +
> 
> DEFAULT_TIMEOUT is unnecessary here. Since the default timeout is already set,
> it makes the call useless.
> 
>> +    ret = watchdog_register_device(&data->wdt_dev);
>> +    if (ret)
>> +        return ret;
>> +
>> +    /* Setup with 1ms timebase */
>> +    writel(((clk_get_rate(data->clk) / 1000) & GXBB_WDT_CTRL_DIV_MASK) |
>> +        GXBB_WDT_CTRL_EE_RESET |
>> +        GXBB_WDT_CTRL_CLK_EN |
>> +        GXBB_WDT_CTRL_CLKDIV_EN,
>> +        data->reg_base + GXBB_WDT_CTRL_REG);
>> +    meson_gxbb_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
> 
> set_timeout already calls the ping function. Also, the functions should be called
> prior to watchdog registration to avoid race conditions.
> 
>> +    meson_gxbb_wdt_ping(&data->wdt_dev);
> 
> This is unusual. If the watchdog can be already running, it might make sense
> to tell the core about it (set WDOG_HW_RUNNING in the status field), so it
> can send heartbeats until user space opens the device.

Yes, since meson_gxbb_wdt_set_timeout() already ping, this is useless.
Guenter Roeck May 27, 2016, 1:48 p.m. UTC | #5 
On 05/27/2016 01:25 AM, Neil Armstrong wrote:
[ ... ]
>>> +    data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
>>> +    data->wdt_dev.min_hw_heartbeat_ms = 1;
>>
>> Does the device require a minimum time between heartbeats ?
>> Just asking, because you violate it yourself below.
>>
>> If you want to set the minimum timeout, that would be min_timeout.
>
> Ok, these values are not very clear actually.
>
Hmmm .. yes, reading the description again, it doesn't really describe well
what it is doing. Essentially, min_hw_heartbeat_ms is enforced by the watchdog
core, and should be used if a watchdog hardware can not tolerate short intervals
between heartbeats. min_timeout is the minimum timeout value configurable from
user space.

>>> +    data->wdt_dev.timeout = DEFAULT_TIMEOUT;
>>> +    watchdog_set_drvdata(&data->wdt_dev, data);
>>> +
>>> +    watchdog_init_timeout(&data->wdt_dev, DEFAULT_TIMEOUT, &pdev->dev);
>>> +
>>
>> DEFAULT_TIMEOUT is unnecessary here. Since the default timeout is already set,
>> it makes the call useless.
>>
>>> +    ret = watchdog_register_device(&data->wdt_dev);
>>> +    if (ret)
>>> +        return ret;
>>> +
>>> +    /* Setup with 1ms timebase */
>>> +    writel(((clk_get_rate(data->clk) / 1000) & GXBB_WDT_CTRL_DIV_MASK) |
>>> +        GXBB_WDT_CTRL_EE_RESET |
>>> +        GXBB_WDT_CTRL_CLK_EN |
>>> +        GXBB_WDT_CTRL_CLKDIV_EN,
>>> +        data->reg_base + GXBB_WDT_CTRL_REG);
>>> +    meson_gxbb_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
>>
>> set_timeout already calls the ping function. Also, the functions should be called
>> prior to watchdog registration to avoid race conditions.
>>
>>> +    meson_gxbb_wdt_ping(&data->wdt_dev);
>>
>> This is unusual. If the watchdog can be already running, it might make sense
>> to tell the core about it (set WDOG_HW_RUNNING in the status field), so it
>> can send heartbeats until user space opens the device.
>
> Yes, since meson_gxbb_wdt_set_timeout() already ping, this is useless.
>

Not only that - if the watchdog _is_ already running at boot time, you should
really set WDOG_HW_RUNNING to let the watchdog core know. You status function
would come handy there.

	if (meson_gxbb_wdt_status(data))	// note the changed parameter
		set_bit(WDOG_HW_RUNNING, &data->wdt_dev.status);

Thanks,
Guenter
Neil Armstrong May 27, 2016, 3:24 p.m. UTC | #6 
On 05/27/2016 03:48 PM, Guenter Roeck wrote:
> On 05/27/2016 01:25 AM, Neil Armstrong wrote:
> [ ... ]
>>>> +    data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
>>>> +    data->wdt_dev.min_hw_heartbeat_ms = 1;
>>>
>>> Does the device require a minimum time between heartbeats ?
>>> Just asking, because you violate it yourself below.
>>>
>>> If you want to set the minimum timeout, that would be min_timeout.
>>
>> Ok, these values are not very clear actually.
>>
> Hmmm .. yes, reading the description again, it doesn't really describe well
> what it is doing. Essentially, min_hw_heartbeat_ms is enforced by the watchdog
> core, and should be used if a watchdog hardware can not tolerate short intervals
> between heartbeats. min_timeout is the minimum timeout value configurable from
> user space.
OK, I'll switch to min_timeout = 1.

> 

[ ... ]

>>>
>>> This is unusual. If the watchdog can be already running, it might make sense
>>> to tell the core about it (set WDOG_HW_RUNNING in the status field), so it
>>> can send heartbeats until user space opens the device.
>>
>> Yes, since meson_gxbb_wdt_set_timeout() already ping, this is useless.
>>
> 
> Not only that - if the watchdog _is_ already running at boot time, you should
> really set WDOG_HW_RUNNING to let the watchdog core know. You status function
> would come handy there.
> 
>     if (meson_gxbb_wdt_status(data))    // note the changed parameter
>         set_bit(WDOG_HW_RUNNING, &data->wdt_dev.status);
Yes, it can be handy.

I will push this feature in a next version, I'll stick to a simpler behavior and check
if it would be running before the kernel starts.

Thanks,
Neil

> 
> Thanks,
> Guenter
>
diff mbox

Patch

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 9bde095..7679d93 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -68,6 +68,7 @@  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_WATCHDOG) += meson_wdt.o
+obj-$(CONFIG_MESON_WATCHDOG) += meson_gxbb_wdt.o
 obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
 obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
 obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
diff --git a/drivers/watchdog/meson_gxbb_wdt.c b/drivers/watchdog/meson_gxbb_wdt.c
new file mode 100644
index 0000000..0c7c0d9
--- /dev/null
+++ b/drivers/watchdog/meson_gxbb_wdt.c
@@ -0,0 +1,287 @@ 
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright (c) 2016 BayLibre, SAS.
+ * Author: Neil Armstrong <narmstrong@baylibre.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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ * The full GNU General Public License is included in this distribution
+ * in the file called COPYING.
+ *
+ * BSD LICENSE
+ *
+ * Copyright (c) 2016 BayLibre, SAS.
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define DEFAULT_TIMEOUT	10	/* seconds */
+
+#define GXBB_WDT_CTRL_REG	0x0
+#define GXBB_WDT_CTRL1_REG	0x4
+#define GXBB_WDT_TCNT_REG	0x8
+#define GXBB_WDT_RSET_REG	0xc
+
+#define GXBB_WDT_CTRL_EE_RESET_NOW	BIT(26)
+
+#define GXBB_WDT_CTRL_CLKDIV_EN	BIT(25)
+#define GXBB_WDT_CTRL_CLK_EN	BIT(24)
+#define GXBB_WDT_CTRL_IRQ_EN	BIT(23)
+#define GXBB_WDT_CTRL_EE_RESET	BIT(21)
+#define GXBB_WDT_CTRL_XTAL_SEL	(0)
+#define GXBB_WDT_CTRL_CLK81_SEL	BIT(19)
+#define GXBB_WDT_CTRL_EN	BIT(18)
+#define GXBB_WDT_CTRL_DIV_MASK	(BIT(18)-1)
+
+#define GXBB_WDT_CTRL1_GPIO_PULSE	BIT(17)
+#define GXBB_WDT_CTRL1_GPIO_POL_RESET_0	BIT(16)
+#define GXBB_WDT_CTRL1_GPIO_POL_RESET_1	(0)
+#define GXBB_WDT_CTRL1_GPIO_PULSE_CNT	(BIT(16)-1)
+
+#define GXBB_WDT_TCNT_SETUP_MASK	(BIT(16)-1)
+#define GXBB_WDT_TCNT_CNT_SHIFT		16
+
+struct meson_gxbb_wdt {
+	void __iomem *reg_base;
+	struct watchdog_device wdt_dev;
+	struct clk *clk;
+};
+
+int meson_gxbb_wdt_start(struct watchdog_device *wdt_dev)
+{
+	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) | GXBB_WDT_CTRL_EN,
+		data->reg_base + GXBB_WDT_CTRL_REG);
+
+	return 0;
+}
+
+int meson_gxbb_wdt_stop(struct watchdog_device *wdt_dev)
+{
+	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) & ~GXBB_WDT_CTRL_EN,
+		data->reg_base + GXBB_WDT_CTRL_REG);
+
+	return 0;
+}
+
+unsigned int meson_gxbb_wdt_status(struct watchdog_device *wdt_dev)
+{
+	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	return !!(readl(data->reg_base + GXBB_WDT_CTRL_REG) & GXBB_WDT_CTRL_EN);
+}
+
+int meson_gxbb_wdt_ping(struct watchdog_device *wdt_dev)
+{
+	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	writel(0, data->reg_base + GXBB_WDT_RSET_REG);
+
+	return 0;
+}
+
+int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
+			       unsigned int timeout)
+{
+	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	if (watchdog_active(wdt_dev))
+		meson_gxbb_wdt_stop(wdt_dev);
+
+	meson_gxbb_wdt_ping(wdt_dev);
+
+	writel(timeout*1000, data->reg_base + GXBB_WDT_TCNT_REG);
+
+	if (watchdog_active(wdt_dev))
+		meson_gxbb_wdt_start(wdt_dev);
+
+	return 0;
+}
+
+unsigned int meson_gxbb_wdt_get_timeleft(struct watchdog_device *wdt_dev)
+{
+	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
+	unsigned long reg;
+
+	reg = readl(data->reg_base + GXBB_WDT_TCNT_REG);
+
+	return ((reg >> GXBB_WDT_TCNT_CNT_SHIFT)-
+			(reg & GXBB_WDT_TCNT_SETUP_MASK)) / 1000;
+}
+
+static const struct watchdog_ops meson_gxbb_wdt_ops = {
+	.start = meson_gxbb_wdt_start,
+	.stop = meson_gxbb_wdt_stop,
+	.status = meson_gxbb_wdt_status,
+	.ping = meson_gxbb_wdt_ping,
+	.set_timeout = meson_gxbb_wdt_set_timeout,
+	.get_timeleft = meson_gxbb_wdt_get_timeleft,
+};
+
+static const struct watchdog_info meson_gxbb_wdt_info = {
+	.identity = "meson-gxbb-wdt",
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+};
+
+static int __maybe_unused meson_gxbb_wdt_resume(struct device *dev)
+{
+	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
+
+	if (watchdog_active(&data->wdt_dev))
+		meson_gxbb_wdt_start(&data->wdt_dev);
+
+	return 0;
+}
+
+static int __maybe_unused meson_gxbb_wdt_suspend(struct device *dev)
+{
+	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
+
+	if (watchdog_active(&data->wdt_dev))
+		meson_gxbb_wdt_stop(&data->wdt_dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops meson_gxbb_wdt_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(meson_gxbb_wdt_suspend, meson_gxbb_wdt_resume)
+};
+
+static const struct of_device_id meson_gxbb_wdt_dt_ids[] = {
+	 { .compatible = "amlogic,meson-gxbb-wdt", },
+	 { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, meson_gxbb_wdt_dt_ids);
+
+static int meson_gxbb_wdt_probe(struct platform_device *pdev)
+{
+	struct meson_gxbb_wdt *data;
+	struct resource *res;
+	int ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->reg_base))
+		return PTR_ERR(data->reg_base);
+
+	data->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(data->clk))
+		return PTR_ERR(data->clk);
+
+	clk_prepare_enable(data->clk);
+
+	platform_set_drvdata(pdev, data);
+
+	data->wdt_dev.parent = &pdev->dev;
+	data->wdt_dev.info = &meson_gxbb_wdt_info;
+	data->wdt_dev.ops = &meson_gxbb_wdt_ops;
+	data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
+	data->wdt_dev.min_hw_heartbeat_ms = 1;
+	data->wdt_dev.timeout = DEFAULT_TIMEOUT;
+	watchdog_set_drvdata(&data->wdt_dev, data);
+
+	watchdog_init_timeout(&data->wdt_dev, DEFAULT_TIMEOUT, &pdev->dev);
+
+	ret = watchdog_register_device(&data->wdt_dev);
+	if (ret)
+		return ret;
+
+	/* Setup with 1ms timebase */
+	writel(((clk_get_rate(data->clk) / 1000) & GXBB_WDT_CTRL_DIV_MASK) |
+		GXBB_WDT_CTRL_EE_RESET |
+		GXBB_WDT_CTRL_CLK_EN |
+		GXBB_WDT_CTRL_CLKDIV_EN,
+		data->reg_base + GXBB_WDT_CTRL_REG);
+	meson_gxbb_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
+	meson_gxbb_wdt_ping(&data->wdt_dev);
+
+	return 0;
+}
+
+static int meson_gxbb_wdt_remove(struct platform_device *pdev)
+{
+	struct meson_gxbb_wdt *data = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&data->wdt_dev);
+
+	return 0;
+}
+
+static void meson_gxbb_wdt_shutdown(struct platform_device *pdev)
+{
+	struct meson_gxbb_wdt *data = platform_get_drvdata(pdev);
+
+	meson_gxbb_wdt_stop(&data->wdt_dev);
+}
+
+static struct platform_driver meson_gxbb_wdt_driver = {
+	.probe	= meson_gxbb_wdt_probe,
+	.remove	= meson_gxbb_wdt_remove,
+	.shutdown = meson_gxbb_wdt_shutdown,
+	.driver = {
+		.name = "meson-gxbb-wdt",
+		.pm = &meson_gxbb_wdt_pm_ops,
+		.of_match_table	= meson_gxbb_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(meson_gxbb_wdt_driver);
+
+MODULE_ALIAS("platform:meson-gxbb-wdt");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_DESCRIPTION("Amlogic Meson GXBB Watchdog timer driver");
+MODULE_LICENSE("Dual BSD/GPL");