Re: [PATCH 2/2] maps/mtd-ram: add an of-platform driver

Grant Likely
2009-05-19T14:57:43Z

On Wed, Jan 21, 2009 at 11:41 AM, Wolfram Sang <w.sang@pengutronix.de> wrote:
> Create an of-aware driver using the now exported generic functions from
> plat-ram.c. A typical oftree snipplet for it looks like this:
>
> sram@04e00000 {
>        compatible = "mtd-ram";
>        reg = <0x04e00000 0x00200000>;
>        bank-width = <2>;
> };
>
> Partitions on this device are not yet supported.

This is a new device tree binding. It must be documented in
Documentation/powerpc/dts-bindings and posted to
devicetree-discuss@ozlabs.org for review.

> diff --git a/drivers/mtd/maps/Makefile b/drivers/mtd/maps/Makefile
> index 6d9ba35..f8e3908 100644
> --- a/drivers/mtd/maps/Makefile
> +++ b/drivers/mtd/maps/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_MTD_WRSBC8260)   += wr_sbc82xx_flash.o
>  obj-$(CONFIG_MTD_DMV182)       += dmv182.o
>  obj-$(CONFIG_MTD_SHARP_SL)     += sharpsl-flash.o
>  obj-$(CONFIG_MTD_PLATRAM)      += plat-ram.o
> +obj-$(CONFIG_MTD_OFRAM)                += of-ram.o
>  obj-$(CONFIG_MTD_OMAP_NOR)     += omap_nor.o
>  obj-$(CONFIG_MTD_INTEL_VR_NOR) += intel_vr_nor.o
>  obj-$(CONFIG_MTD_BFIN_ASYNC)   += bfin-async-flash.o
> diff --git a/drivers/mtd/maps/of-ram.c b/drivers/mtd/maps/of-ram.c
> new file mode 100644
> index 0000000..4d334a9
> --- /dev/null
> +++ b/drivers/mtd/maps/of-ram.c
> @@ -0,0 +1,120 @@
> +/*
> + * drivers/mtd/maps/of-ram.c
> + *
> + * Generic of device based RAM map
> + *
> + * Copyright (C) 2009 Wolfram Sang, Pengutronix
> + *
> + * Using plat-ram.c by Ben Dooks
> + *
> + * 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.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/of_device.h>
> +#include <linux/of_platform.h>
> +#include <linux/mtd/plat-ram.h>
> +
> +static int of_ram_probe(struct of_device *op, const struct of_device_id *match)

__devinit

> +{
> +       struct platdata_mtd_ram *pdata;
> +       struct resource *resource;
> +       const char *name;
> +       const u32 *bankwidth;
> +       int ret = -ENOMEM;
> +
> +       pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
> +       if (!pdata)
> +               goto bad0;
> +       op->dev.platform_data = pdata;
> +
> +       name = of_get_property(op->node, "name", NULL);
> +       if (!name) {
> +               ret = -ENOENT;
> +               dev_dbg(&op->dev, "could not get node name\n");
> +               goto bad1;
> +       }
> +
> +       resource = kzalloc(sizeof(struct resource), GFP_KERNEL);
> +       if (!resource)
> +               goto bad1;

Why isn't resource on the stack?

> +
> +       if (of_address_to_resource(op->node, 0, resource)) {
> +               ret = -ENXIO;
> +               dev_dbg(&op->dev, "could not create resource\n");
> +               goto bad2;
> +       }
> +
> +       bankwidth = of_get_property(op->node, "bank-width", NULL);
> +       if (*bankwidth == 0) {
> +               ret = -ENOENT;
> +               dev_dbg(&op->dev, "bank width not set\n");
> +               goto bad2;
> +       }
> +       pdata->bankwidth = *bankwidth;
> +
> +       ret = __platram_probe(&op->dev, name, resource, pdata);
> +       kfree(resource);
> +
> +       if (ret)
> +               goto bad1;
> +
> +       return 0;
> +
> + bad2:
> +       kfree(resource);
> + bad1:
> +       op->dev.platform_data = NULL;
> +       kfree(pdata);
> + bad0:
> +       return ret;

I'd rather see more meaningful labels. ie "err_kalloc:" and
"err_platram_probe:".

> +}
> +
> +static int of_ram_remove(struct of_device *op)

__devexit

> +{
> +       int ret;
> +       struct platdata_mtd_ram *pdata = op->dev.platform_data;
> +
> +       ret = __platram_remove(&op->dev);
> +       op->dev.platform_data = NULL;
> +       kfree(pdata);
> +       return ret;
> +}
> +
> +static struct of_device_id of_ram_match[] = {
> +       { .compatible = "mtd-ram", },
> +       {},
> +};
> +MODULE_DEVICE_TABLE(of, of_ram_match);
> +
> +static struct of_platform_driver of_ram_driver = {

__devinitdata

> +       .owner = THIS_MODULE,
> +       .name = "of-ram",

This name is too generic for an of_platform device. 'mtd' needs to be
in there somewhere.

> +       .match_table = of_ram_match,
> +       .probe = of_ram_probe,
> +       .remove = of_ram_remove,

__devexit_p()

> +};
> +
> +static int __init of_ram_init(void)
> +{
> +       return of_register_platform_driver(&of_ram_driver);
> +}
> +
> +static void __exit of_ram_exit(void)
> +{
> +       of_unregister_platform_driver(&of_ram_driver);
> +}
> +
> +module_init(of_ram_init);

Put the module_init() statement directly after the of_ram_init() definition.

> +module_exit(of_ram_exit);
> +
> +MODULE_AUTHOR("Wolfram Sang");
> +MODULE_DESCRIPTION("MTD OF RAM map driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.5.6.5
>
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>

--
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.