Re: [PATCH v2 6/9] misc: Generic on-chip SRAM allocation driver

[Shawn Guo <shawn.guo@linaro.org>]

On Fri, Aug 31, 2012 at 11:27:01AM +0200, Philipp Zabel wrote:
> This driver requests and remaps a memory region as configured in the
> device tree. It serves memory from this region via the genalloc API.
> 
> Other drivers can retrieve the genalloc pool from a phandle pointing
> to this drivers' device node in the device tree.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
>  drivers/misc/Kconfig  |    8 ++++
>  drivers/misc/Makefile |    1 +
>  drivers/misc/sram.c   |  105 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 114 insertions(+)
>  create mode 100644 drivers/misc/sram.c
> 
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 98a442d..8a55284 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -509,6 +509,14 @@ config USB_SWITCH_FSA9480
>  	  stereo and mono audio, video, microphone and UART data to use
>  	  a common connector port.
>  
> +config SRAM
> +	bool "Generic on-chip SRAM driver\n"

Remove the "\n".

And "depends on HAS_IOMEM"?

> +	select GENERIC_ALLOCATOR
> +	help
> +	  This driver allows to declare a memory region to be managed
> +	  by the genalloc API. It is supposed to be used for small
> +	  on-chip SRAM areas found on many ARM SoCs.
> +
>  source "drivers/misc/c2port/Kconfig"
>  source "drivers/misc/eeprom/Kconfig"
>  source "drivers/misc/cb710/Kconfig"
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index b88df7a..ccc759a 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -50,3 +50,4 @@ obj-y				+= carma/
>  obj-$(CONFIG_USB_SWITCH_FSA9480) += fsa9480.o
>  obj-$(CONFIG_ALTERA_STAPL)	+=altera-stapl/
>  obj-$(CONFIG_INTEL_MEI)		+= mei/
> +obj-$(CONFIG_SRAM)		+= sram.o
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> new file mode 100644
> index 0000000..c5cf67e
> --- /dev/null
> +++ b/drivers/misc/sram.c
> @@ -0,0 +1,105 @@
> +/*
> + * Generic on-chip SRAM allocation driver
> + *
> + * Copyright (C) 2012 Philipp Zabel, Pengutronix
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
> + * MA 02110-1301, USA.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/genalloc.h>
> +
> +struct sram_dev {
> +	struct gen_pool *pool;
> +};
> +
> +static int __devinit sram_probe(struct platform_device *pdev)
> +{
> +	void __iomem *virt_base;
> +	struct sram_dev *sram;
> +	struct resource *res;
> +	unsigned long size;
> +	int ret;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
> +
> +	size = resource_size(res);
> +
> +	virt_base = devm_request_and_ioremap(&pdev->dev, res);
> +	if (!virt_base)
> +		return -ENOMEM;

The kerneldoc of devm_request_and_ioremap suggests -EADDRNOTAVAIL.

Regards,
Shawn

> +
> +	sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
> +	if (!sram)
> +		return -ENOMEM;
> +
> +	sram->pool = gen_pool_create(PAGE_SHIFT, -1);
> +	if (!sram->pool)
> +		return -ENOMEM;
> +
> +	ret = gen_pool_add_virt(sram->pool, (unsigned long)virt_base,
> +				res->start, size, -1);
> +	if (ret < 0) {
> +		gen_pool_destroy(sram->pool);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, sram);
> +
> +	dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
> +
> +	return 0;
> +}
> +
> +static int __devexit sram_remove(struct platform_device *pdev)
> +{
> +	struct sram_dev *sram = platform_get_drvdata(pdev);
> +
> +	if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
> +		dev_dbg(&pdev->dev, "removed while SRAM allocated\n");
> +
> +	gen_pool_destroy(sram->pool);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static struct of_device_id sram_dt_ids[] = {
> +	{ .compatible = "sram" },
> +	{ /* sentinel */ }
> +};
> +#endif
> +
> +static struct platform_driver sram_driver = {
> +	.driver = {
> +		.name = "sram",
> +		.of_match_table = of_match_ptr(sram_dt_ids),
> +	},
> +	.probe = sram_probe,
> +	.remove = __devexit_p(sram_remove),
> +};
> +
> +module_platform_driver(sram_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Philipp Zabel, Pengutronix");
> +MODULE_DESCRIPTION("Generic SRAM allocator driver");
> -- 
> 1.7.10.4
>