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Date:   Wed, 8 Aug 2018 17:10:58 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Maxime Jourdan <maxi.jourdan@...adoo.fr>,
        Kevin Hilman <khilman@...libre.com>
Cc:     linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/4] soc: amlogic: add meson-canvas driver

On 08/08/2018 09:45, Jerome Brunet wrote:
> On Wed, 2018-08-08 at 00:00 +0200, Maxime Jourdan wrote:
>> Amlogic SoCs have a repository of 256 canvas which they use to
>> describe pixel buffers.
>>
>> They contain metadata like width, height, block mode, endianness [..]
>>
>> Many IPs within those SoCs like vdec/vpu rely on those canvas to read/write
>> pixels.
>>
>> Signed-off-by: Maxime Jourdan <maxi.jourdan@...adoo.fr>
>> Tested-by: Neil Armstrong <narmstrong@...libre.com>
> 
> Thanks for making the changes Martin, I do prefer this version. You did not have
> to drop the ops, until it is really needed because of some SoC quirks, I guess
> it is simpler this way
> 
> With some answers to the nitpicks below, feel free to add :
> 
> Reviewed-by: Jerome Brunet <jbrunet@...libre.com>
> 
>> ---
>>  drivers/soc/amlogic/Kconfig              |   7 +
>>  drivers/soc/amlogic/Makefile             |   1 +
>>  drivers/soc/amlogic/meson-canvas.c       | 185 +++++++++++++++++++++++
>>  include/linux/soc/amlogic/meson-canvas.h |  65 ++++++++
>>  4 files changed, 258 insertions(+)
>>  create mode 100644 drivers/soc/amlogic/meson-canvas.c
>>  create mode 100644 include/linux/soc/amlogic/meson-canvas.h
>>
>> diff --git a/drivers/soc/amlogic/Kconfig b/drivers/soc/amlogic/Kconfig
>> index b04f6e4aedbc..2f282b472912 100644
>> --- a/drivers/soc/amlogic/Kconfig
>> +++ b/drivers/soc/amlogic/Kconfig
>> @@ -1,5 +1,12 @@
>>  menu "Amlogic SoC drivers"
>>  
>> +config MESON_CANVAS
>> +	tristate "Amlogic Meson Canvas driver"
>> +	depends on ARCH_MESON || COMPILE_TEST
>> +	default n
>> +	help
>> +	  Say yes to support the canvas IP for Amlogic SoCs.
>> +
>>  config MESON_GX_SOCINFO
>>  	bool "Amlogic Meson GX SoC Information driver"
>>  	depends on ARCH_MESON || COMPILE_TEST
>> diff --git a/drivers/soc/amlogic/Makefile b/drivers/soc/amlogic/Makefile
>> index 8fa321893928..0ab16d35ac36 100644
>> --- a/drivers/soc/amlogic/Makefile
>> +++ b/drivers/soc/amlogic/Makefile
>> @@ -1,3 +1,4 @@
>> +obj-$(CONFIG_MESON_CANVAS) += meson-canvas.o
>>  obj-$(CONFIG_MESON_GX_SOCINFO) += meson-gx-socinfo.o
>>  obj-$(CONFIG_MESON_GX_PM_DOMAINS) += meson-gx-pwrc-vpu.o
>>  obj-$(CONFIG_MESON_MX_SOCINFO) += meson-mx-socinfo.o
>> diff --git a/drivers/soc/amlogic/meson-canvas.c b/drivers/soc/amlogic/meson-canvas.c
>> new file mode 100644
>> index 000000000000..c461334b36d4
>> --- /dev/null
>> +++ b/drivers/soc/amlogic/meson-canvas.c
>> @@ -0,0 +1,185 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2018 Maxime Jourdan <maxi.jourdan@...adoo.fr>
>> + * Copyright (C) 2016 BayLibre, SAS
>> + * Author: Neil Armstrong <narmstrong@...libre.com>
>> + * Copyright (C) 2015 Amlogic, Inc. All rights reserved.
>> + * Copyright (C) 2014 Endless Mobile
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <linux/module.h>
>> +#include <linux/regmap.h>
>> +#include <linux/soc/amlogic/meson-canvas.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/io.h>
>> +
>> +#define NUM_CANVAS 256
>> +
>> +/* DMC Registers */
>> +#define DMC_CAV_LUT_DATAL	0x48 /* 0x12 offset in data sheet */
>> +	#define CANVAS_WIDTH_LBIT	29
>> +	#define CANVAS_WIDTH_LWID       3
>> +#define DMC_CAV_LUT_DATAH	0x4c /* 0x13 offset in data sheet */
>> +	#define CANVAS_WIDTH_HBIT       0
>> +	#define CANVAS_HEIGHT_BIT       9
>> +	#define CANVAS_BLKMODE_BIT      24
>> +#define DMC_CAV_LUT_ADDR	0x50 /* 0x14 offset in data sheet */
>> +	#define CANVAS_LUT_WR_EN        (0x2 << 8)
>> +	#define CANVAS_LUT_RD_EN        (0x1 << 8)
>> +
>> +struct meson_canvas {
>> +	struct device *dev;
>> +	struct regmap *regmap_dmc;
>> +	spinlock_t lock; /* canvas device lock */
>> +	u8 used[NUM_CANVAS];
>> +};
>> +
>> +struct meson_canvas *meson_canvas_get(struct device *dev)
>> +{
>> +	struct device_node *canvas_node;
>> +	struct platform_device *canvas_pdev;
>> +	struct meson_canvas *canvas;
>> +
>> +	canvas_node = of_parse_phandle(dev->of_node, "amlogic,canvas", 0);
>> +	if (!canvas_node)
>> +		return ERR_PTR(-ENODEV);
>> +
>> +	canvas_pdev = of_find_device_by_node(canvas_node);
>> +	if (!canvas_pdev) {
>> +		dev_err(dev, "Unable to find canvas pdev\n");
>> +		return ERR_PTR(-ENODEV);
>> +	}

I should be -EPROBE_DEFER here since the canvas driver maybe hasn't probed yet.

>> +
>> +	canvas = dev_get_drvdata(&canvas_pdev->dev);
>> +	if (!canvas)
>> +		return ERR_PTR(-ENODEV);
> 
> You've got your device at this point, maybe EINVAL instead ?

This shouldn't fail here... I'm not sure what should be the error.

> 
>> +
>> +	return canvas;
>> +}
>> +EXPORT_SYMBOL_GPL(meson_canvas_get);
>> +
>> +int meson_canvas_setup(struct meson_canvas *canvas, u8 canvas_index,
>> +		       u32 addr, u32 stride, u32 height,
>> +		       unsigned int wrap,
>> +		       unsigned int blkmode,
>> +		       unsigned int endian)
>> +{
>> +	struct regmap *regmap = canvas->regmap_dmc;
>> +	unsigned long flags;
>> +	u32 val;
>> +
>> +	spin_lock_irqsave(&canvas->lock, flags);
>> +	if (!canvas->used[canvas_index]) {
>> +		dev_err(canvas->dev,
>> +			"Trying to setup non allocated canvas %u\n",
>> +			canvas_index);
>> +		spin_unlock_irqrestore(&canvas->lock, flags);
>> +		return -EINVAL;
>> +	}
>> +
>> +	regmap_write(regmap, DMC_CAV_LUT_DATAL,
>> +		     ((addr + 7) >> 3) |
>> +		     (((stride + 7) >> 3) << CANVAS_WIDTH_LBIT));
>> +
>> +	regmap_write(regmap, DMC_CAV_LUT_DATAH,
>> +		     ((((stride + 7) >> 3) >> CANVAS_WIDTH_LWID) <<
>> +						CANVAS_WIDTH_HBIT) |
>> +		     (height << CANVAS_HEIGHT_BIT) |
>> +		     (wrap << 22) |
>> +		     (blkmode << CANVAS_BLKMODE_BIT) |
>> +		     (endian << 26));
>> +
>> +	regmap_write(regmap, DMC_CAV_LUT_ADDR,
>> +		     CANVAS_LUT_WR_EN | canvas_index);
>> +
>> +	/* Force a read-back to make sure everything is flushed. */
>> +	regmap_read(regmap, DMC_CAV_LUT_DATAH, &val);
> 
> I suppose this something you got from the vendor kernel ? Out of curiosity, have
> you tried w/o it ? I am wondering if this is really necessary ? 


It's explicit in the Amlogic source, you need a readback to make sure it's taken in account.

> 
> 
>> +	spin_unlock_irqrestore(&canvas->lock, flags);
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(meson_canvas_setup);
>> +
>> +int meson_canvas_alloc(struct meson_canvas *canvas, u8 *canvas_index)
>> +{
>> +	int i;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&canvas->lock, flags);
>> +	for (i = 0; i < NUM_CANVAS; ++i) {
>> +		if (!canvas->used[i]) {
>> +			canvas->used[i] = 1;
>> +			spin_unlock_irqrestore(&canvas->lock, flags);
>> +			*canvas_index = i;
>> +			return 0;
>> +		}
>> +	}
>> +	spin_unlock_irqrestore(&canvas->lock, flags);
>> +
>> +	dev_err(canvas->dev, "No more canvas available\n");
>> +	return -ENODEV;
>> +}
>> +EXPORT_SYMBOL_GPL(meson_canvas_alloc);
>> +
>> +int meson_canvas_free(struct meson_canvas *canvas, u8 canvas_index)
>> +{
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&canvas->lock, flags);
>> +	if (!canvas->used[canvas_index]) {
>> +		dev_err(canvas->dev,
>> +			"Trying to free unused canvas %u\n", canvas_index);
>> +		spin_unlock_irqrestore(&canvas->lock, flags);
>> +		return -EINVAL;
>> +	}
>> +	canvas->used[canvas_index] = 0;
>> +	spin_unlock_irqrestore(&canvas->lock, flags);
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(meson_canvas_free);
>> +
>> +static int meson_canvas_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct meson_canvas *canvas;
>> +
>> +	canvas = devm_kzalloc(dev, sizeof(*canvas), GFP_KERNEL);
>> +	if (!canvas)
>> +		return -ENOMEM;
>> +
>> +	canvas->regmap_dmc =
>> +		syscon_node_to_regmap(of_get_parent(dev->of_node));
>> +	if (IS_ERR(canvas->regmap_dmc)) {
>> +		dev_err(dev, "failed to get DMC regmap\n");
>> +		return PTR_ERR(canvas->regmap_dmc);
>> +	}
>> +
>> +	canvas->dev = dev;
>> +	spin_lock_init(&canvas->lock);
>> +	dev_set_drvdata(dev, canvas);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id canvas_dt_match[] = {
>> +	{ .compatible = "amlogic,canvas" },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, canvas_dt_match);
>> +
>> +static struct platform_driver meson_canvas_driver = {
>> +	.probe = meson_canvas_probe,
>> +	.driver = {
>> +		.name = "amlogic-canvas",
>> +		.of_match_table = canvas_dt_match,
>> +	},
>> +};
>> +module_platform_driver(meson_canvas_driver);
>> +
>> +MODULE_DESCRIPTION("Amlogic Canvas driver");
>> +MODULE_AUTHOR("Maxime Jourdan <maxi.jourdan@...adoo.fr>");
>> +MODULE_LICENSE("GPL");
>> diff --git a/include/linux/soc/amlogic/meson-canvas.h b/include/linux/soc/amlogic/meson-canvas.h
>> new file mode 100644
>> index 000000000000..c164202d8e39
>> --- /dev/null
>> +++ b/include/linux/soc/amlogic/meson-canvas.h
>> @@ -0,0 +1,65 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ */
>> +/*
>> + * Copyright (C) 2018 Maxime Jourdan <maxi.jourdan@...adoo.fr>
>> + */
>> +#ifndef MESON_CANVAS_H
>> +#define MESON_CANVAS_H
>> +
>> +#include <linux/kernel.h>
>> +
>> +#define MESON_CANVAS_WRAP_NONE	0x00
>> +#define MESON_CANVAS_WRAP_X	0x01
>> +#define MESON_CANVAS_WRAP_Y	0x02
>> +
>> +#define MESON_CANVAS_BLKMODE_LINEAR	0x00
>> +#define MESON_CANVAS_BLKMODE_32x32	0x01
>> +#define MESON_CANVAS_BLKMODE_64x64	0x02
>> +
>> +#define MESON_CANVAS_ENDIAN_SWAP16	0x1
>> +#define MESON_CANVAS_ENDIAN_SWAP32	0x3
>> +#define MESON_CANVAS_ENDIAN_SWAP64	0x7
>> +#define MESON_CANVAS_ENDIAN_SWAP128	0xf
>> +
>> +struct meson_canvas;
>> +
>> +/**
>> + * meson_canvas_get() - get a canvas provider instance
>> + *
>> + * @dev: your device
> 
> s/your device/consumer device pointer ?
> 
>> + */
>> +struct meson_canvas *meson_canvas_get(struct device *dev);
>> +
>> +/**
>> + * meson_canvas_alloc() - take ownership of a canvas
>> + *
>> + * @canvas: canvas provider instance retrieved from meson_canvas_get()
>> + * @canvas_index: will be filled with the canvas ID
>> + */
>> +int meson_canvas_alloc(struct meson_canvas *canvas, u8 *canvas_index);
>> +
>> +/**
>> + * meson_canvas_free() - remove ownership from a canvas
>> + *
>> + * @canvas: canvas provider instance retrieved from meson_canvas_get()
>> + * @canvas_index: canvas ID that was obtained via meson_canvas_alloc()
>> + */
>> +int meson_canvas_free(struct meson_canvas *canvas, u8 canvas_index);
>> +
>> +/**
>> + * meson_canvas_setup() - configure a canvas
>> + *
>> + * @canvas: canvas provider instance retrieved from meson_canvas_get()
>> + * @canvas_index: canvas ID that was obtained via meson_canvas_alloc()
>> + * @addr: physical address to the pixel buffer
>> + * @stride: width of the buffer
>> + * @height: height of the buffer
>> + * @wrap: undocumented
>> + * @blkmode: block mode (linear, 32x32, 64x64)
>> + * @endian: byte swapping (swap16, swap32, swap64, swap128)
>> + */
>> +int meson_canvas_setup(struct meson_canvas *canvas, u8 canvas_index,
>> +		       u32 addr, u32 stride, u32 height,
>> +		       unsigned int wrap, unsigned int blkmode,
>> +		       unsigned int endian);
>> +
>> +#endif
> 
> 

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