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Date: Wed, 27 Mar 2013 15:27:23 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Grant Likely <grant.likely@...retlab.ca>,
Rob Herring <rob.herring@...xeda.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Shawn Guo <shawn.guo@...aro.org>,
Huang Shijie <shijie8@...il.com>,
Dong Aisheng <dong.aisheng@...aro.org>,
Matt Porter <mporter@...com>,
Fabio Estevam <fabio.estevam@...escale.com>,
Javier Martin <javier.martin@...ta-silicon.com>,
kernel@...gutronix.de, devicetree-discuss@...ts.ozlabs.org
Subject: Re: [PATCH v9 RESEND 2/4] misc: Generic on-chip SRAM allocation
driver
On Wed, 20 Mar 2013 11:52:45 +0100 Philipp Zabel <p.zabel@...gutronix.de> 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.
> It optionally enables the SRAM clock.
>
> Other drivers can retrieve the genalloc pool from a phandle pointing
> to this drivers' device node in the device tree.
>
> The allocation granularity is hard-coded to 32 bytes for now,
> to make the SRAM driver useful for the 6502 remoteproc driver.
> There is overhead for bigger SRAMs, where only a much coarser
> allocation granularity is needed: At 32 bytes minimum allocation
> size, a 256 KiB SRAM needs a 1 KiB bitmap to track allocations.
>
> Documentation/devicetree/bindings/misc/sram.txt | 16 +++
> drivers/misc/Kconfig | 9 ++
> drivers/misc/Makefile | 1 +
> drivers/misc/sram.c | 121 +++++++++++++++++++++++
drivers/misc/sram.c is a pretty generic-sounding thing. Is it really
Linux's One True SRAM driver? How many different sorts of sram devices
do we expect this can be used with? If I don't use DT?
In other words, perhaps this should have a more specific and accurate
name?
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -510,6 +510,15 @@ config LATTICE_ECP3_CONFIG
>
> If unsure, say N.
>
> ...
>
> +static int 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 -EADDRNOTAVAIL;
EADDRNOTAVAIL is a networking error. If your users see this error pop
up on their console they'll start wiggling ethernet cables, wondering
why that didn't fix it.
> + sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
> + if (!sram)
> + return -ENOMEM;
> +
> + sram->clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(sram->clk))
> + sram->clk = NULL;
> + else
> + clk_prepare_enable(sram->clk);
> +
> + sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -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;
> +}
>
> ...
>
> +int __init sram_init(void)
> +{
> + return platform_driver_register(&sram_driver);
> +}
> +
> +postcore_initcall(sram_init);
Why is it postcore_initcall()?
Fixlets:
From: Andrew Morton <akpm@...ux-foundation.org>
Subject: misc-generic-on-chip-sram-allocation-driver-fix
fix Kconfig text, make sram_init static
Cc: Dong Aisheng <dong.aisheng@...aro.org>
Cc: Fabio Estevam <fabio.estevam@...escale.com>
Cc: Grant Likely <grant.likely@...retlab.ca>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Huang Shijie <shijie8@...il.com>
Cc: Javier Martin <javier.martin@...ta-silicon.com>
Cc: Matt Porter <mporter@...com>
Cc: Michal Simek <monstr@...str.eu>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>
Cc: Philipp Zabel <p.zabel@...gutronix.de>
Cc: Rob Herring <rob.herring@...xeda.com>
Cc: Shawn Guo <shawn.guo@...aro.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
drivers/misc/Kconfig | 6 +++---
drivers/misc/sram.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff -puN Documentation/devicetree/bindings/misc/sram.txt~misc-generic-on-chip-sram-allocation-driver-fix Documentation/devicetree/bindings/misc/sram.txt
diff -puN drivers/misc/Kconfig~misc-generic-on-chip-sram-allocation-driver-fix drivers/misc/Kconfig
--- a/drivers/misc/Kconfig~misc-generic-on-chip-sram-allocation-driver-fix
+++ a/drivers/misc/Kconfig
@@ -523,9 +523,9 @@ config SRAM
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 SoCs.
+ This driver allows you 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 SoCs.
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
diff -puN drivers/misc/Makefile~misc-generic-on-chip-sram-allocation-driver-fix drivers/misc/Makefile
diff -puN drivers/misc/sram.c~misc-generic-on-chip-sram-allocation-driver-fix drivers/misc/sram.c
--- a/drivers/misc/sram.c~misc-generic-on-chip-sram-allocation-driver-fix
+++ a/drivers/misc/sram.c
@@ -113,7 +113,7 @@ static struct platform_driver sram_drive
.remove = sram_remove,
};
-int __init sram_init(void)
+static int __init sram_init(void)
{
return platform_driver_register(&sram_driver);
}
_
--
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