Re: [PATCH v3 2/3] mtd: devices: elm: Add support for ELM error correction
On 12/10/2012 12:13 PM, Philip, Avinash wrote:
> On Fri, Dec 07, 2012 at 16:07:23, Nori, Sekhar wrote:
>> On 11/29/2012 5:16 PM, Philip, Avinash wrote:
[...]
>>> +struct device *elm_request(enum bch_ecc bch_type)
>>> +{
>>> + struct elm_info *info;
>>> +
>>> + list_for_each_entry(info, &elm_devices, list) {
>>> + if (info && info->dev) {
>>> + info->bch_type = bch_type;
>>> + elm_config(info);
>>> + return info->dev;
>>> + }
>>> + }
>>
>> This will always return the first ELM device probed since you never
>> remove the allocated device from the list.
>
> But now I realized that, there is no mechanism of freeing the requested
> resource.
Right. You essentially want to assign an ELM instance to work with a
given instance of GPMC and that could be done statically too. Just pass
phandle of ELM node in GPMC DT data?
> So I will add mechanism to request ELM module successfully only if ELM
> module is not requested already and add mechanism to free it, on NAND
> driver module unload (loadable module support). This way ELM driver
> can achieve multi instance support.
>
>> I wonder why you really need a list?
>
> The prime motivation for the list is the driver should support multi
> instances of ELM by removing global symbols.
I still think a request/free API is bit too much for something that will
turn out to be a simple 1-to-1 match anyway. Can you please look at the
phandle suggestion above? I am no DT expert, but I think that will work
for your use case.
Thanks,
Sekhar
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RE: [PATCH v3 2/3] mtd: devices: elm: Add support for ELM error correction
On Tue, Dec 11, 2012 at 14:33:56, Grant Likely wrote: > On Thu, 29 Nov 2012 17:16:33 +0530, "Philip, Avinash" > wrote: > > The ELM hardware module can be used to speedup BCH 4/8/16 ECC scheme > > error correction. > > For now only 4 & 8 bit support is added > > > > Signed-off-by: Philip, Avinash > > Cc: Grant Likely > > Cc: Rob Herring > > Cc: Rob Landley > > --- > > Changes since v2: > > - Remove __devinit & __devexit annotations > > > > Changes since v1: > > - Change build attribute to CONFIG_MTD_NAND_OMAP_BCH > > - Reduced indentation using by passing elm_info , offset > > to elm_read & elm_write > > - Removed syndrome manipulation functions. > > > > :00 100644 000... b88ee83... A > > Documentation/devicetree/bindings/mtd/elm.txt > > :100644 100644 395733a... 369a194... M drivers/mtd/devices/Makefile > > :00 100644 000... d2667f3... A drivers/mtd/devices/elm.c > > :00 100644 000... d4fce31... A > > include/linux/platform_data/elm.h > > Documentation/devicetree/bindings/mtd/elm.txt | 17 + > > drivers/mtd/devices/Makefile |4 +- > > drivers/mtd/devices/elm.c | 418 > > + > > include/linux/platform_data/elm.h | 54 > > 4 files changed, 493 insertions(+), 1 deletions(-) > > > > diff --git a/Documentation/devicetree/bindings/mtd/elm.txt > > b/Documentation/devicetree/bindings/mtd/elm.txt > > new file mode 100644 > > index 000..b88ee83 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/mtd/elm.txt > > @@ -0,0 +1,17 @@ > > +Error location module > > + > > +Required properties: > > +- compatible: Must be "ti,elm" > > Compatible string is too generic. Need to specify a specific SoC here. > ie: "ti,omap3430-elm" I will change to "ti,am33xx-elm" in next version. Thanks Avinash > > Otherwise the binding looks fine. I haven't reviewed the code though. > > g. > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v3 2/3] mtd: devices: elm: Add support for ELM error correction
On Thu, 29 Nov 2012 17:16:33 +0530, "Philip, Avinash" wrote: > The ELM hardware module can be used to speedup BCH 4/8/16 ECC scheme > error correction. > For now only 4 & 8 bit support is added > > Signed-off-by: Philip, Avinash > Cc: Grant Likely > Cc: Rob Herring > Cc: Rob Landley > --- > Changes since v2: > - Remove __devinit & __devexit annotations > > Changes since v1: > - Change build attribute to CONFIG_MTD_NAND_OMAP_BCH > - Reduced indentation using by passing elm_info , offset > to elm_read & elm_write > - Removed syndrome manipulation functions. > > :00 100644 000... b88ee83... A > Documentation/devicetree/bindings/mtd/elm.txt > :100644 100644 395733a... 369a194... Mdrivers/mtd/devices/Makefile > :00 100644 000... d2667f3... Adrivers/mtd/devices/elm.c > :00 100644 000... d4fce31... A > include/linux/platform_data/elm.h > Documentation/devicetree/bindings/mtd/elm.txt | 17 + > drivers/mtd/devices/Makefile |4 +- > drivers/mtd/devices/elm.c | 418 > + > include/linux/platform_data/elm.h | 54 > 4 files changed, 493 insertions(+), 1 deletions(-) > > diff --git a/Documentation/devicetree/bindings/mtd/elm.txt > b/Documentation/devicetree/bindings/mtd/elm.txt > new file mode 100644 > index 000..b88ee83 > --- /dev/null > +++ b/Documentation/devicetree/bindings/mtd/elm.txt > @@ -0,0 +1,17 @@ > +Error location module > + > +Required properties: > +- compatible: Must be "ti,elm" Compatible string is too generic. Need to specify a specific SoC here. ie: "ti,omap3430-elm" Otherwise the binding looks fine. I haven't reviewed the code though. g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
RE: [PATCH v3 2/3] mtd: devices: elm: Add support for ELM error correction
On Fri, Dec 07, 2012 at 16:07:23, Nori, Sekhar wrote:
> On 11/29/2012 5:16 PM, Philip, Avinash wrote:
> > The ELM hardware module can be used to speedup BCH 4/8/16 ECC scheme
> > error correction.
> > For now only 4 & 8 bit support is added
> >
> > Signed-off-by: Philip, Avinash
> > Cc: Grant Likely
> > Cc: Rob Herring
> > Cc: Rob Landley
[...]
/**
> > + * elm_config - Configure ELM module
> > + * @info: elm info
> > + */
> > +static void elm_config(struct elm_info *info)
>
> This is called "config", but there is no configuration information
> passed which looks odd..
The config information is bch_type, encapsulated in struct elm_info.
>
> > +{
> > + u32 reg_val;
> > +
> > + reg_val = (info->bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
> > + elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
> > +}
>
> Is there a use case where BCH type needs to be changed after NAND has
> been probed?
No, I think kernel handles the entire NAND part with a single ecc layout.
Hence there is no run time BCH switching. But ELM driver should support BCH
4 & 8. Selection of BCH information comes from DT of NAND driver.
As NAND driver supporting BCH4 & 8 ecc scheme ELM module support
configuration of both. Configuration of ELM module should done as part
of NAND driver probing.
> You will have to erase any existing data written to NAND if
> you change the ECC type. That sounds destructive enough to avoid such a
> thing.
There is no support for BCH switching after NAND driver probing.
[...]
> > +struct device *elm_request(enum bch_ecc bch_type)
> > +{
> > + struct elm_info *info;
> > +
> > + list_for_each_entry(info, &elm_devices, list) {
> > + if (info && info->dev) {
> > + info->bch_type = bch_type;
> > + elm_config(info);
> > + return info->dev;
> > + }
> > + }
>
> This will always return the first ELM device probed since you never
> remove the allocated device from the list.
But now I realized that, there is no mechanism of freeing the requested
resource.
So I will add mechanism to request ELM module successfully only if ELM
module is not requested already and add mechanism to free it, on NAND
driver module unload (loadable module support). This way ELM driver
can achieve multi instance support.
> I wonder why you really need a list?
The prime motivation for the list is the driver should support multi
instances of ELM by removing global symbols.
Thanks
Avinash
>
> Thanks,
> Sekhar
>
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Re: [PATCH v3 2/3] mtd: devices: elm: Add support for ELM error correction
On 11/29/2012 5:16 PM, Philip, Avinash wrote:
> The ELM hardware module can be used to speedup BCH 4/8/16 ECC scheme
> error correction.
> For now only 4 & 8 bit support is added
>
> Signed-off-by: Philip, Avinash
> Cc: Grant Likely
> Cc: Rob Herring
> Cc: Rob Landley
> ---
> Changes since v2:
> - Remove __devinit & __devexit annotations
>
> Changes since v1:
> - Change build attribute to CONFIG_MTD_NAND_OMAP_BCH
> - Reduced indentation using by passing elm_info , offset
> to elm_read & elm_write
> - Removed syndrome manipulation functions.
>
> :00 100644 000... b88ee83... A
> Documentation/devicetree/bindings/mtd/elm.txt
> :100644 100644 395733a... 369a194... Mdrivers/mtd/devices/Makefile
> :00 100644 000... d2667f3... Adrivers/mtd/devices/elm.c
> :00 100644 000... d4fce31... A
> include/linux/platform_data/elm.h
> Documentation/devicetree/bindings/mtd/elm.txt | 17 +
> drivers/mtd/devices/Makefile |4 +-
> drivers/mtd/devices/elm.c | 418
> +
> include/linux/platform_data/elm.h | 54
> 4 files changed, 493 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/elm.txt
> b/Documentation/devicetree/bindings/mtd/elm.txt
> new file mode 100644
> index 000..b88ee83
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/elm.txt
> @@ -0,0 +1,17 @@
> +Error location module
> +
> +Required properties:
> +- compatible: Must be "ti,elm"
> +- reg: physical base address and size of the registers map.
> +- interrupts: Interrupt number for the elm.
> +- interrupt-parent: The parent interrupt controller
> +
> +Optional properties:
> +- ti,hwmods: Name of the hwmod associated to the elm
> +
> +Example:
> +elm: elm@0 {
> + compatible = "ti,elm";
> + reg = <0x4808 0x2000>;
> + interrupts = <4>;
> +};
> diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
> index 395733a..369a194 100644
> --- a/drivers/mtd/devices/Makefile
> +++ b/drivers/mtd/devices/Makefile
> @@ -17,8 +17,10 @@ obj-$(CONFIG_MTD_LART) += lart.o
> obj-$(CONFIG_MTD_BLOCK2MTD) += block2mtd.o
> obj-$(CONFIG_MTD_DATAFLASH) += mtd_dataflash.o
> obj-$(CONFIG_MTD_M25P80) += m25p80.o
> +obj-$(CONFIG_MTD_NAND_OMAP_BCH) += elm.o
> obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
> obj-$(CONFIG_MTD_SST25L) += sst25l.o
> obj-$(CONFIG_MTD_BCM47XXSFLASH) += bcm47xxsflash.o
>
> -CFLAGS_docg3.o += -I$(src)
> \ No newline at end of file
> +
> +CFLAGS_docg3.o += -I$(src)
> diff --git a/drivers/mtd/devices/elm.c b/drivers/mtd/devices/elm.c
> new file mode 100644
> index 000..d2667f3
> --- /dev/null
> +++ b/drivers/mtd/devices/elm.c
> @@ -0,0 +1,418 @@
> +/*
> + * Error Location Module
> + *
> + * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
> + *
> + * 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.
> + *
> + */
> +
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> +#include
> +
> +#define ELM_IRQSTATUS0x018
> +#define ELM_IRQENABLE0x01c
> +#define ELM_LOCATION_CONFIG 0x020
> +#define ELM_PAGE_CTRL0x080
> +#define ELM_SYNDROME_FRAGMENT_0 0x400
> +#define ELM_SYNDROME_FRAGMENT_6 0x418
> +#define ELM_LOCATION_STATUS 0x800
> +#define ELM_ERROR_LOCATION_0 0x880
> +
> +/* ELM Interrupt Status Register */
> +#define INTR_STATUS_PAGE_VALID BIT(8)
> +
> +/* ELM Interrupt Enable Register */
> +#define INTR_EN_PAGE_MASKBIT(8)
> +
> +/* ELM Location Configuration Register */
> +#define ECC_BCH_LEVEL_MASK 0x3
> +
> +/* ELM syndrome */
> +#define ELM_SYNDROME_VALID BIT(16)
> +
> +/* ELM_LOCATION_STATUS Register */
> +#define ECC_CORRECTABLE_MASK BIT(8)
> +#define ECC_NB_ERRORS_MASK 0x1f
> +
> +/* ELM_ERROR_LOCATION_0-15 Registers */
> +#define ECC_ERROR_LOCATION_MASK 0x1fff
> +
> +#define ELM_ECC_SIZE 0x7ff
> +
> +#define SYNDROME_FRAGMENT_REG_SIZE 0x40
> +#define ERROR_LOCATION_SIZE 0x100
> +
> +struct elm_info {
> + struct device *dev;
> + void __iomem *elm_base;
> + struct completion elm_completion;
> + struct list_head list;
> + enum bch_ecc bch_type;
> +};
> +
> +static LIST_H
