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Date:   Tue, 29 Sep 2020 11:52:14 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Alexandre Bailon <abailon@baylibre.com>
Cc:     ohad@wizery.com, bjorn.andersson@linaro.org, robh+dt@kernel.org,
        matthias.bgg@gmail.com, linux-remoteproc@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        stephane.leprovost@mediatek.com, gpain@baylibre.com
Subject: Re: [PATCH v2 2/4] remoteproc: Add a remoteproc driver for the
 MT8183's APU
Message-ID: <20200929175214.GB124290@xps15>
References: <20200910130148.8734-1-abailon@baylibre.com>
 <20200910130148.8734-3-abailon@baylibre.com>
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In-Reply-To: <20200910130148.8734-3-abailon@baylibre.com>
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Hi Alexandre,

On Thu, Sep 10, 2020 at 03:01:46PM +0200, Alexandre Bailon wrote:
> This adds a driver to control the APU present in the MT8183.
> This loads the firmware and start the DSP.
> 
> Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
> ---
>  drivers/remoteproc/Kconfig   |  10 ++
>  drivers/remoteproc/Makefile  |   1 +
>  drivers/remoteproc/mtk_apu.c | 288 +++++++++++++++++++++++++++++++++++
>  3 files changed, 299 insertions(+)
>  create mode 100644 drivers/remoteproc/mtk_apu.c
> 
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index c6659dfea7c7..4ebea57bf4c8 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -51,6 +51,16 @@ config MTK_SCP
>  
>  	  It's safe to say N here.
>  
> +config MTK_APU
> +	tristate "Mediatek APU remoteproc support"
> +	depends on ARCH_MEDIATEK
> +	depends on MTK_IOMMU
> +	help
> +	  Say y to support the Mediatek's Accelerated Processing Unit (APU) via
> +	  the remote processor framework.
> +
> +	  It's safe to say N here.
> +
>  config OMAP_REMOTEPROC
>  	tristate "OMAP remoteproc support"
>  	depends on ARCH_OMAP4 || SOC_OMAP5 || SOC_DRA7XX
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index 3dfa28e6c701..174644f38fda 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_REMOTEPROC_CDEV)		+= remoteproc_cdev.o
>  obj-$(CONFIG_IMX_REMOTEPROC)		+= imx_rproc.o
>  obj-$(CONFIG_INGENIC_VPU_RPROC)		+= ingenic_rproc.o
>  obj-$(CONFIG_MTK_SCP)			+= mtk_scp.o mtk_scp_ipi.o
> +obj-$(CONFIG_MTK_APU)			+= mtk_apu.o
>  obj-$(CONFIG_OMAP_REMOTEPROC)		+= omap_remoteproc.o
>  obj-$(CONFIG_WKUP_M3_RPROC)		+= wkup_m3_rproc.o
>  obj-$(CONFIG_DA8XX_REMOTEPROC)		+= da8xx_remoteproc.o
> diff --git a/drivers/remoteproc/mtk_apu.c b/drivers/remoteproc/mtk_apu.c
> new file mode 100644
> index 000000000000..6d2f577cfde5
> --- /dev/null
> +++ b/drivers/remoteproc/mtk_apu.c
> @@ -0,0 +1,288 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 BayLibre SAS
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/highmem.h>

Not sure what this is for

> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iommu.h>
> +#include <linux/irq.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/platform_device.h>
> +#include <linux/remoteproc.h>
> +
> +#include "remoteproc_internal.h"
> +
> +/* From MT8183 4.5 Vision Processor Unit (VPU).pdf datasheet */
> +#define SW_RST					(0x0000000C)
> +#define SW_RST_OCD_HALT_ON_RST			BIT(12)
> +#define SW_RST_IPU_D_RST			BIT(8)
> +#define SW_RST_IPU_B_RST			BIT(4)
> +#define CORE_CTRL				(0x00000110)
> +#define CORE_CTRL_PDEBUG_ENABLE			BIT(31)
> +#define CORE_CTRL_SRAM_64K_iMEM			(0x00 << 27)
> +#define CORE_CTRL_SRAM_96K_iMEM			(0x01 << 27)
> +#define CORE_CTRL_SRAM_128K_iMEM		(0x02 << 27)
> +#define CORE_CTRL_SRAM_192K_iMEM		(0x03 << 27)
> +#define CORE_CTRL_SRAM_256K_iMEM		(0x04 << 27)
> +#define CORE_CTRL_PBCLK_ENABLE			BIT(26)
> +#define CORE_CTRL_RUN_STALL			BIT(23)
> +#define CORE_CTRL_STATE_VECTOR_SELECT		BIT(19)
> +#define CORE_CTRL_PIF_GATED			BIT(17)
> +#define CORE_CTRL_NMI				BIT(0)
> +#define CORE_XTENSA_INT				(0x00000114)
> +#define CORE_CTL_XTENSA_INT			(0x00000118)
> +#define CORE_DEFAULT0				(0x0000013C)
> +#define CORE_DEFAULT0_QOS_SWAP_0		(0x00 << 28)
> +#define CORE_DEFAULT0_QOS_SWAP_1		(0x01 << 28)
> +#define CORE_DEFAULT0_QOS_SWAP_2		(0x02 << 28)
> +#define CORE_DEFAULT0_QOS_SWAP_3		(0x03 << 28)
> +#define CORE_DEFAULT0_ARUSER_USE_IOMMU		(0x10 << 23)
> +#define CORE_DEFAULT0_AWUSER_USE_IOMMU		(0x10 << 18)
> +#define CORE_DEFAULT1				(0x00000140)
> +#define CORE_DEFAULT0_ARUSER_IDMA_USE_IOMMU	(0x10 << 0)
> +#define CORE_DEFAULT0_AWUSER_IDMA_USE_IOMMU	(0x10 << 5)
> +#define CORE_XTENSA_ALTRESETVEC			(0x000001F8)
> +
> +struct mtk_apu_rproc {
> +	struct device *dev;
> +	struct rproc *rproc;

As far as I can tell @rproc is only used in apu_jtag_probe(), but it could just
as easily be given as a parameter to the function instead of bloating the
structure.

> +

Extra line

> +	void __iomem *base;
> +	int irq;
> +	struct clk_bulk_data clks[3];
> +};
> +
> +static int mtk_apu_rproc_prepare(struct rproc *rproc)
> +{
> +	struct mtk_apu_rproc *apu_rproc = rproc->priv;
> +	int ret;
> +
> +	ret = clk_bulk_prepare_enable(ARRAY_SIZE(apu_rproc->clks),
> +				      apu_rproc->clks);
> +	if (ret)
> +		dev_err(apu_rproc->dev, "Failed to enable clocks\n");
> +
> +	return ret;
> +}
> +
> +static int mtk_apu_rproc_unprepare(struct rproc *rproc)
> +{
> +	struct mtk_apu_rproc *apu_rproc = rproc->priv;
> +
> +	clk_bulk_disable_unprepare(ARRAY_SIZE(apu_rproc->clks),
> +				   apu_rproc->clks);
> +
> +	return 0;
> +}
> +
> +static int mtk_apu_rproc_start(struct rproc *rproc)
> +{
> +	struct mtk_apu_rproc *apu_rproc = rproc->priv;
> +	u32 core_ctrl;
> +
> +	/* Set reset vector of APU firmware boot address */
> +	writel(rproc->bootaddr, apu_rproc->base + CORE_XTENSA_ALTRESETVEC);
> +
> +	/* Turn on the clocks and stall the APU */
> +	core_ctrl = readl(apu_rproc->base + CORE_CTRL);
> +	core_ctrl |= CORE_CTRL_PDEBUG_ENABLE | CORE_CTRL_PBCLK_ENABLE |
> +		     CORE_CTRL_STATE_VECTOR_SELECT | CORE_CTRL_RUN_STALL |
> +		     CORE_CTRL_PIF_GATED;
> +	writel(core_ctrl, apu_rproc->base + CORE_CTRL);
> +
> +	/* Reset the APU */
> +	writel(SW_RST_OCD_HALT_ON_RST | SW_RST_IPU_B_RST | SW_RST_IPU_D_RST,
> +		apu_rproc->base + SW_RST);
> +	ndelay(27);

What is this for and why 27 nanosecond precicely?  Is this a board specific
setting?  Are we sure it is the same value on all platform with a MT8183? 

Matthias, what is your take on this? 

> +	writel(0, apu_rproc->base + SW_RST);
> +
> +	core_ctrl &= ~CORE_CTRL_PIF_GATED;
> +	writel(core_ctrl, apu_rproc->base + CORE_CTRL);
> +
> +	/* Configure memory accesses to go through the IOMMU */
> +	writel(CORE_DEFAULT0_AWUSER_USE_IOMMU | CORE_DEFAULT0_ARUSER_USE_IOMMU |
> +	      CORE_DEFAULT0_QOS_SWAP_1, apu_rproc->base + CORE_DEFAULT0);
> +	writel(CORE_DEFAULT0_AWUSER_IDMA_USE_IOMMU |
> +		CORE_DEFAULT0_ARUSER_IDMA_USE_IOMMU,
> +		apu_rproc->base + CORE_DEFAULT1);
> +
> +	/* Release the APU */
> +	core_ctrl &= ~CORE_CTRL_RUN_STALL;
> +	writel(core_ctrl, apu_rproc->base + CORE_CTRL);
> +
> +	return 0;
> +}
> +
> +static int mtk_apu_rproc_stop(struct rproc *rproc)
> +{
> +	struct mtk_apu_rproc *apu_rproc = rproc->priv;
> +	u32 core_ctrl;
> +
> +	core_ctrl = readl(apu_rproc->base + CORE_CTRL);
> +	writel(core_ctrl | CORE_CTRL_RUN_STALL, apu_rproc->base + CORE_CTRL);
> +
> +	return 0;
> +}
> +
> +static void mtk_apu_rproc_kick(struct rproc *rproc, int vqid)
> +{
> +	struct mtk_apu_rproc *apu_rproc = rproc->priv;
> +
> +	writel(1 << vqid, apu_rproc->base + CORE_CTL_XTENSA_INT);
> +}
> +
> +static const struct rproc_ops mtk_apu_rproc_ops = {
> +	.prepare	= mtk_apu_rproc_prepare,
> +	.unprepare	= mtk_apu_rproc_unprepare,
> +	.start		= mtk_apu_rproc_start,
> +	.stop		= mtk_apu_rproc_stop,
> +	.kick		= mtk_apu_rproc_kick,
> +};
> +
> +static irqreturn_t mtk_apu_rproc_callback(int irq, void *data)
> +{
> +	struct rproc *rproc = data;
> +	struct mtk_apu_rproc *apu_rproc = (struct mtk_apu_rproc *)rproc->priv;
> +
> +	writel(1, apu_rproc->base + CORE_XTENSA_INT);
> +
> +	return IRQ_WAKE_THREAD;
> +}
> +
> +static irqreturn_t handle_event(int irq, void *data)
> +{
> +	struct rproc *rproc = data;
> +
> +	rproc_vq_interrupt(rproc, 0);
> +	rproc_vq_interrupt(rproc, 1);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int mtk_apu_rproc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct mtk_apu_rproc *apu_rproc;
> +	struct rproc *rproc;
> +	struct resource *res;
> +	int ret;
> +
> +	rproc = rproc_alloc(dev, dev_name(dev), &mtk_apu_rproc_ops, NULL,
> +			    sizeof(*apu_rproc));
> +	if (!rproc)
> +		return -ENOMEM;
> +
> +	rproc->recovery_disabled = true;
> +	rproc->has_iommu = false;
> +
> +	apu_rproc = rproc->priv;
> +	apu_rproc->rproc = rproc;
> +	apu_rproc->dev = dev;
> +
> +	platform_set_drvdata(pdev, rproc);
> +
> +	rproc->domain = iommu_get_domain_for_dev(dev);

Any reason why iommu_get_domain_for_dev() is explicitly called rather than
setting ->has_iommu to true and let the remoteproc core get the domain for
you?

> +	if (!rproc->domain) {
> +		dev_err(dev, "Failed to get the IOMMU domain\n");
> +		ret = -EINVAL;
> +		goto free_rproc;
> +	}
> +
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	apu_rproc->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(apu_rproc->base)) {
> +		dev_err(dev, "Failed to map mmio\n");
> +		ret = PTR_ERR(apu_rproc->base);
> +		goto free_rproc;
> +	}
> +
> +	apu_rproc->irq = platform_get_irq(pdev, 0);
> +	if (apu_rproc->irq < 0) {
> +		ret = apu_rproc->irq;
> +		goto free_rproc;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, apu_rproc->irq,
> +					mtk_apu_rproc_callback, handle_event,
> +					IRQF_SHARED | IRQF_ONESHOT,
> +					NULL, rproc);
> +	if (ret) {
> +		dev_err(dev, "devm_request_threaded_irq error: %d\n", ret);
> +		goto free_rproc;
> +	}
> +
> +	apu_rproc->clks[0].id = "ipu";
> +	apu_rproc->clks[1].id = "axi";
> +	apu_rproc->clks[1].id = "jtag";
> +
> +	ret = devm_clk_bulk_get(dev, ARRAY_SIZE(apu_rproc->clks),
> +				apu_rproc->clks);
> +	if (ret) {
> +		dev_err(dev, "Failed to get clocks\n");
> +		goto free_rproc;
> +	}
> +
> +	ret = of_reserved_mem_device_init(dev);
> +	if (ret) {
> +		dev_err(dev, "device does not have specific CMA pool\n");
> +		goto free_rproc;
> +	}
> +
> +	ret = rproc_add(rproc);
> +	if (ret) {
> +		dev_err(dev, "rproc_add failed: %d\n", ret);
> +		goto free_mem;
> +	}
> +
> +	return 0;
> +
> +free_mem:
> +	of_reserved_mem_device_release(dev);
> +free_rproc:
> +	rproc_free(rproc);
> +
> +	return ret;
> +}
> +
> +static int mtk_apu_rproc_remove(struct platform_device *pdev)
> +{
> +	struct rproc *rproc = platform_get_drvdata(pdev);
> +	struct mtk_apu_rproc *apu_rproc = (struct mtk_apu_rproc *)rproc->priv;
> +	struct device *dev = &pdev->dev;
> +
> +	disable_irq(apu_rproc->irq);
> +
> +	rproc_del(rproc);
> +	of_reserved_mem_device_release(dev);
> +	rproc_free(rproc);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id mtk_apu_rproc_of_match[] = {
> +	{ .compatible = "mediatek,mt8183-apu", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, mtk_apu_rproc_of_match);
> +
> +static struct platform_driver mtk_apu_rproc_driver = {
> +	.probe = mtk_apu_rproc_probe,
> +	.remove = mtk_apu_rproc_remove,
> +	.driver = {
> +		.name = "mtk_apu-rproc",
> +		.of_match_table = of_match_ptr(mtk_apu_rproc_of_match),
> +	},
> +};
> +module_platform_driver(mtk_apu_rproc_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Alexandre Bailon");
> +MODULE_DESCRIPTION("MTK APU Remote Processor control driver");
> -- 
> 2.26.2
>