Re: [PATCH v3 06/15] drivers: reset: Add STM32 reset driver

[Philipp Zabel <p.zabel@pengutronix.de>]

Am Donnerstag, den 12.03.2015, 22:55 +0100 schrieb Maxime Coquelin:
> From: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> 
> The STM32 MCUs family IP can be reset by accessing some shared registers.
> 
> The specificity is that some reset lines are used by the timers.
> At timer initialization time, the timer has to be reset, that's why
> we cannot use a regular driver.

But this is a regular driver now, should this comment be updated?

> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> ---
>  drivers/reset/Makefile      |   1 +
>  drivers/reset/reset-stm32.c | 125 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 126 insertions(+)
>  create mode 100644 drivers/reset/reset-stm32.c
> 
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 157d421..aed12d1 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -1,5 +1,6 @@
>  obj-$(CONFIG_RESET_CONTROLLER) += core.o
>  obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o
>  obj-$(CONFIG_ARCH_BERLIN) += reset-berlin.o
> +obj-$(CONFIG_ARCH_STM32) += reset-stm32.o
>  obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
>  obj-$(CONFIG_ARCH_STI) += sti/
> diff --git a/drivers/reset/reset-stm32.c b/drivers/reset/reset-stm32.c
> new file mode 100644
> index 0000000..0d389b1
> --- /dev/null
> +++ b/drivers/reset/reset-stm32.c
> @@ -0,0 +1,125 @@
> +/*
> + * Copyright (C) Maxime Coquelin 2015
> + * Author:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
> + * License terms:  GNU General Public License (GPL), version 2
> + *
> + * Heavily based on sunxi driver from Maxime Ripard.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/types.h>
> +
> +struct stm32_reset_data {
> +	spinlock_t			lock;
> +	void __iomem			*membase;
> +	struct reset_controller_dev	rcdev;
> +};
> +
> +static int stm32_reset_assert(struct reset_controller_dev *rcdev,
> +			      unsigned long id)
> +{
> +	struct stm32_reset_data *data = container_of(rcdev,
> +						     struct stm32_reset_data,
> +						     rcdev);
> +	int bank = id / BITS_PER_LONG;
> +	int offset = id % BITS_PER_LONG;
> +	unsigned long flags;
> +	u32 reg;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	reg = readl_relaxed(data->membase + (bank * 4));
> +	writel_relaxed(reg | BIT(offset), data->membase + (bank * 4));
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
> +				unsigned long id)
> +{
> +	struct stm32_reset_data *data = container_of(rcdev,
> +						     struct stm32_reset_data,
> +						     rcdev);
> +	int bank = id / BITS_PER_LONG;
> +	int offset = id % BITS_PER_LONG;
> +	unsigned long flags;
> +	u32 reg;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	reg = readl_relaxed(data->membase + (bank * 4));
> +	writel_relaxed(reg & ~BIT(offset), data->membase + (bank * 4));
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static struct reset_control_ops stm32_reset_ops = {
> +	.assert		= stm32_reset_assert,
> +	.deassert	= stm32_reset_deassert,
> +};
> +
> +static const struct of_device_id stm32_reset_dt_ids[] = {
> +	 { .compatible = "st,stm32-rcc", },
> +	 { /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, sstm32_reset_dt_ids);
> +
> +static int stm32_reset_probe(struct platform_device *pdev)
> +{
> +	struct stm32_reset_data *data;
> +	struct resource *res;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	data->membase = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(data->membase))
> +		return PTR_ERR(data->membase);
> +
> +	spin_lock_init(&data->lock);
> +
> +	data->rcdev.owner = THIS_MODULE;
> +	data->rcdev.nr_resets = resource_size(res) * 8;
> +	data->rcdev.ops = &stm32_reset_ops;
> +	data->rcdev.of_node = pdev->dev.of_node;
> +
> +	return reset_controller_register(&data->rcdev);
> +}
> +
> +static int stm32_reset_remove(struct platform_device *pdev)
> +{
> +	struct stm32_reset_data *data = platform_get_drvdata(pdev);
> +
> +	reset_controller_unregister(&data->rcdev);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver stm32_reset_driver = {
> +	.probe	= stm32_reset_probe,
> +	.remove	= stm32_reset_remove,
> +	.driver = {
> +		.name		= "stm32-rcc-reset",
> +		.of_match_table	= stm32_reset_dt_ids,
> +	},
> +};
> +module_platform_driver(stm32_reset_driver);
> +
> +MODULE_AUTHOR("Maxime Coquelin <maxime.coquelin@gmail.com>");
> +MODULE_DESCRIPTION("STM32 MCUs Reset Controller Driver");
> +MODULE_LICENSE("GPL");
> +

regards
Philipp