Subject: Re: [PATCH 5/5] drivers: uio: new driver for fsl_85xx_cache_sram

From: Greg KH <[email-masked]>
Date: Wed, 15 Apr 2020 14:49:29 +0200

On Wed, Apr 15, 2020 at 05:33:46AM -0700, Wang Wenhu wrote:
> A driver for freescale 85xx platforms to access the Cache-Sram form
> user level. This is extremely helpful for some user-space applications
> that require high performance memory accesses.
> 
> Cc: Greg Kroah-Hartman <[email-masked]>
> Cc: Christophe Leroy <[email-masked]>
> Cc: Scott Wood <[email-masked]>
> Cc: Michael Ellerman <[email-masked]>
> Cc: [email-masked]
> Signed-off-by: Wang Wenhu <[email-masked]>
> ---
>  drivers/uio/Kconfig                   |   8 ++
>  drivers/uio/Makefile                  |   1 +
>  drivers/uio/uio_fsl_85xx_cache_sram.c | 195 ++++++++++++++++++++++++++
>  3 files changed, 204 insertions(+)
>  create mode 100644 drivers/uio/uio_fsl_85xx_cache_sram.c
> 
> diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> index 202ee81cfc2b..afd38ec13de0 100644
> --- a/drivers/uio/Kconfig
> +++ b/drivers/uio/Kconfig
> @@ -105,6 +105,14 @@ config UIO_NETX
>  	  To compile this driver as a module, choose M here; the module
>  	  will be called uio_netx.
>  
> +config UIO_FSL_85XX_CACHE_SRAM
> +	tristate "Freescale 85xx Cache-Sram driver"
> +	depends on FSL_85XX_CACHE_SRAM
> +	help
> +	  Generic driver for accessing the Cache-Sram form user level. This
> +	  is extremely helpful for some user-space applications that require
> +	  high performance memory accesses.
> +
>  config UIO_FSL_ELBC_GPCM
>  	tristate "eLBC/GPCM driver"
>  	depends on FSL_LBC
> diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
> index c285dd2a4539..be2056cffc21 100644
> --- a/drivers/uio/Makefile
> +++ b/drivers/uio/Makefile
> @@ -10,4 +10,5 @@ obj-$(CONFIG_UIO_NETX)	+= uio_netx.o
>  obj-$(CONFIG_UIO_PRUSS)         += uio_pruss.o
>  obj-$(CONFIG_UIO_MF624)         += uio_mf624.o
>  obj-$(CONFIG_UIO_FSL_ELBC_GPCM)	+= uio_fsl_elbc_gpcm.o
> +obj-$(CONFIG_UIO_FSL_85XX_CACHE_SRAM)	+= uio_fsl_85xx_cache_sram.o
>  obj-$(CONFIG_UIO_HV_GENERIC)	+= uio_hv_generic.o
> diff --git a/drivers/uio/uio_fsl_85xx_cache_sram.c b/drivers/uio/uio_fsl_85xx_cache_sram.c
> new file mode 100644
> index 000000000000..e11202dd5b93
> --- /dev/null
> +++ b/drivers/uio/uio_fsl_85xx_cache_sram.c
> @@ -0,0 +1,195 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Vivo Communication Technology Co. Ltd.
> + * Copyright (C) 2020 Wang Wenhu <[email-masked]>
> + * All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> + * by the Free Software Foundation.

Nit, you don't need this sentance anymore now that you have the SPDX
line above

> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/uio_driver.h>
> +#include <linux/stringify.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <asm/fsl_85xx_cache_sram.h>
> +
> +#define DRIVER_VERSION	"0.1.0"

Don't do DRIVER_VERSIONs, they never work once the code is in the kernel
tree.

> +#define DRIVER_NAME	"uio_fsl_85xx_cache_sram"

KBUILD_MODNAME?

> +#define UIO_NAME	"uio_cache_sram"
> +
> +static const struct of_device_id uio_mpc85xx_l2ctlr_of_match[] = {
> +	{	.compatible = "uio,fsl,p2020-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p2010-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1020-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1011-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1013-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1022-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,mpc8548-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,mpc8544-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,mpc8572-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,mpc8536-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1021-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1012-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1025-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1016-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1024-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1015-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,p1010-l2-cache-controller",	},
> +	{	.compatible = "uio,fsl,bsc9131-l2-cache-controller",	},
> +	{},
> +};
> +
> +static void uio_info_free_internal(struct uio_info *info)
> +{
> +	struct uio_mem *uiomem = &info->mem[0];
> +
> +	while (uiomem < &info->mem[MAX_UIO_MAPS]) {
> +		if (uiomem->size) {
> +			mpc85xx_cache_sram_free(uiomem->internal_addr);
> +			kfree(uiomem->name);
> +		}
> +		uiomem++;
> +	}
> +}
> +
> +static int uio_fsl_85xx_cache_sram_probe(struct platform_device *pdev)
> +{
> +	struct device_node *parent = pdev->dev.of_node;
> +	struct device_node *node = NULL;
> +	struct uio_info *info;
> +	struct uio_mem *uiomem;
> +	const char *dt_name;
> +	u32 mem_size;
> +	u32 align;
> +	void *virt;
> +	phys_addr_t phys;
> +	int ret = -ENODEV;
> +
> +	/* alloc uio_info for one device */
> +	info = kzalloc(sizeof(*info), GFP_KERNEL);
> +	if (!info) {
> +		dev_err(&pdev->dev, "kzalloc uio_info failed\n");

kzalloc already says this.

> +		ret = -ENOMEM;
> +		goto err_out;
> +	}
> +
> +	/* get optional uio name */
> +	if (of_property_read_string(parent, "uio_name", &dt_name))
> +		dt_name = UIO_NAME;
> +
> +	info->name = kstrdup(dt_name, GFP_KERNEL);
> +	if (!info->name) {
> +		dev_err(&pdev->dev, "error kstrdup uio_name\n");

kstrdup should have given you an error string already, right?

> +		ret = -ENOMEM;
> +		goto err_info_free;
> +	}
> +
> +	uiomem = &info->mem[0];
> +	for_each_child_of_node(parent, node) {
> +		if (!node) {
> +			dev_err(&pdev->dev, "device's OF-node is NULL\n");

How can this happen?

> +			continue;

Why not error out?

> +		}
> +
> +		ret = of_property_read_u32(node, "cache-mem-size", &mem_size);
> +		if (ret) {
> +			dev_err(&pdev->dev, "missing cache-mem-size value\n");

You don't exit?

> +			continue;
> +		}
> +
> +		if (mem_size == 0) {
> +			dev_err(&pdev->dev, "cache-mem-size should not be 0\n");

Again, you don't exit?

> +			continue;
> +		}
> +
> +		align = 2;
> +		while (align < mem_size)
> +			align *= 2;
> +		virt = mpc85xx_cache_sram_alloc(mem_size, &phys, align);
> +		if (!virt) {
> +			dev_err(&pdev->dev, "allocate 0x%x cache-mem failed\n", mem_size);

You don't exit?

> +			continue;
> +		}
> +
> +		uiomem->memtype = UIO_MEM_PHYS;
> +		uiomem->addr = phys;
> +		uiomem->size = mem_size;
> +		uiomem->name = kstrdup(node->name, GFP_KERNEL);;
> +		uiomem->internal_addr = virt;
> +		++uiomem;
> +
> +		if (uiomem >= &info->mem[MAX_UIO_MAPS]) {
> +			dev_warn(&pdev->dev, "device has more than "
> +				 __stringify(MAX_UIO_MAPS)
> +				 " I/O memory resources.\n");

What can someone do with that?

thanks,

greg k-h