Re: [PATCH v2 6/7] soc: mediatek: mmsys: Add reset controller support

[Matthias Brugger <matthias.bgg@gmail.com>]

On 14/07/2021 12:11, Enric Balletbo i Serra wrote:
> Among other features the mmsys driver should implement a reset
> controller to be able to reset different bits from their space.
> 
> Cc: Jitao Shi <jitao.shi@mediatek.com>
> Suggested-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

I'm happy to take this, as soon as we have the updated binding description.

Regards,
Matthias

> ---
> 
> (no changes since v1)
> 
>  drivers/soc/mediatek/mtk-mmsys.c | 69 ++++++++++++++++++++++++++++++++
>  drivers/soc/mediatek/mtk-mmsys.h |  2 +
>  2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-mmsys.c b/drivers/soc/mediatek/mtk-mmsys.c
> index e681029fe804..6ac4deff0164 100644
> --- a/drivers/soc/mediatek/mtk-mmsys.c
> +++ b/drivers/soc/mediatek/mtk-mmsys.c
> @@ -4,10 +4,12 @@
>   * Author: James Liao <jamesjj.liao@mediatek.com>
>   */
>  
> +#include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/io.h>
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
>  #include <linux/soc/mediatek/mtk-mmsys.h>
>  
>  #include "mtk-mmsys.h"
> @@ -55,6 +57,8 @@ static const struct mtk_mmsys_driver_data mt8183_mmsys_driver_data = {
>  struct mtk_mmsys {
>  	void __iomem *regs;
>  	const struct mtk_mmsys_driver_data *data;
> +	spinlock_t lock; /* protects mmsys_sw_rst_b reg */
> +	struct reset_controller_dev rcdev;
>  };
>  
>  void mtk_mmsys_ddp_connect(struct device *dev,
> @@ -91,6 +95,59 @@ void mtk_mmsys_ddp_disconnect(struct device *dev,
>  }
>  EXPORT_SYMBOL_GPL(mtk_mmsys_ddp_disconnect);
>  
> +static int mtk_mmsys_reset_update(struct reset_controller_dev *rcdev, unsigned long id,
> +				  bool assert)
> +{
> +	struct mtk_mmsys *mmsys = container_of(rcdev, struct mtk_mmsys, rcdev);
> +	unsigned long flags;
> +	u32 reg;
> +	int i;
> +
> +	spin_lock_irqsave(&mmsys->lock, flags);
> +
> +	reg = readl_relaxed(mmsys->regs + MMSYS_SW0_RST_B);
> +
> +	if (assert)
> +		reg &= ~BIT(id);
> +	else
> +		reg |= BIT(id);
> +
> +	writel_relaxed(reg, mmsys->regs + MMSYS_SW0_RST_B);
> +
> +	spin_unlock_irqrestore(&mmsys->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int mtk_mmsys_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> +	return mtk_mmsys_reset_update(rcdev, id, true);
> +}
> +
> +static int mtk_mmsys_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> +	return mtk_mmsys_reset_update(rcdev, id, false);
> +}
> +
> +static int mtk_mmsys_reset(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> +	int ret;
> +
> +	ret = mtk_mmsys_reset_assert(rcdev, id);
> +	if (ret)
> +		return ret;
> +
> +	usleep_range(1000, 1100);
> +
> +	return mtk_mmsys_reset_deassert(rcdev, id);
> +}
> +
> +static const struct reset_control_ops mtk_mmsys_reset_ops = {
> +	.assert = mtk_mmsys_reset_assert,
> +	.deassert = mtk_mmsys_reset_deassert,
> +	.reset = mtk_mmsys_reset,
> +};
> +
>  static int mtk_mmsys_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -111,6 +168,18 @@ static int mtk_mmsys_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	spin_lock_init(&mmsys->lock);
> +
> +	mmsys->rcdev.owner = THIS_MODULE;
> +	mmsys->rcdev.nr_resets = 32;
> +	mmsys->rcdev.ops = &mtk_mmsys_reset_ops;
> +	mmsys->rcdev.of_node = pdev->dev.of_node;
> +	ret = devm_reset_controller_register(&pdev->dev, &mmsys->rcdev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Couldn't register mmsys reset controller: %d\n", ret);
> +		return ret;
> +	}
> +
>  	mmsys->data = of_device_get_match_data(&pdev->dev);
>  	platform_set_drvdata(pdev, mmsys);
>  
> diff --git a/drivers/soc/mediatek/mtk-mmsys.h b/drivers/soc/mediatek/mtk-mmsys.h
> index 11388961dded..f9f9e12ceab8 100644
> --- a/drivers/soc/mediatek/mtk-mmsys.h
> +++ b/drivers/soc/mediatek/mtk-mmsys.h
> @@ -66,6 +66,8 @@
>  #define DPI_SEL_IN_BLS				0x0
>  #define DSI_SEL_IN_RDMA				0x1
>  
> +#define MMSYS_SW0_RST_B				0x140
> +
>  struct mtk_mmsys_routes {
>  	u32 from_comp;
>  	u32 to_comp;
>