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Date: Fri, 6 Feb 2015 18:45:44 +0000
From: Mark Rutland <mark.rutland@....com>
To: "tthayer@...nsource.altera.com" <tthayer@...nsource.altera.com>
Cc: "bp@...en8.de" <bp@...en8.de>,
"dougthompson@...ssion.com" <dougthompson@...ssion.com>,
"m.chehab@...sung.com" <m.chehab@...sung.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
Pawel Moll <Pawel.Moll@....com>,
"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
"galak@...eaurora.org" <galak@...eaurora.org>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"dinguyen@...nsource.altera.com" <dinguyen@...nsource.altera.com>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"tthayer.linux@...il.com" <tthayer.linux@...il.com>
Subject: Re: [PATCHv6 2/5] arm: socfpga: Enable OCRAM ECC on startup.
On Fri, Jan 09, 2015 at 02:53:53AM +0000, tthayer@...nsource.altera.com wrote:
> From: Thor Thayer <tthayer@...nsource.altera.com>
>
> This patch enables the ECC for On-Chip RAM on machine
> startup. The ECC has to be enabled before data is
> is stored in memory otherwise the ECC will fail on
> reads.
Where else is this OCRAM used?
If we need the ECC to be enabled before use, a module_init call that
seems to be unrelated to any other usage doesn't seem right to me.
Hopefully I've just misunderstood something here.
>
> Signed-off-by: Thor Thayer <tthayer@...nsource.altera.com>
> ---
> v2: Split OCRAM ECC portion separately. Addition of iounmap()
> and reorganization of gen_pool_free. Remove defconfig from patch.
>
> v3/4: No change
>
> v5: Remove ocram.h, use io.h instead of clk-provider.h
> Check prop in correct place. Add ECC EN defines.
>
> v6: Implement OCRAM discovery changes from community. Add
> of_node_put(). Remove be32_to_cpup(). Use __init() which
> allows removal of .init_machine(). Update year in header.
> ---
> arch/arm/mach-socfpga/Makefile | 1 +
> arch/arm/mach-socfpga/ocram.c | 97 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 98 insertions(+)
> create mode 100644 arch/arm/mach-socfpga/ocram.c
>
> diff --git a/arch/arm/mach-socfpga/Makefile b/arch/arm/mach-socfpga/Makefile
> index 142609e..1552ca5 100644
> --- a/arch/arm/mach-socfpga/Makefile
> +++ b/arch/arm/mach-socfpga/Makefile
> @@ -5,3 +5,4 @@
> obj-y := socfpga.o
> obj-$(CONFIG_SMP) += headsmp.o platsmp.o
> obj-$(CONFIG_EDAC_ALTERA_L2C) += l2_cache.o
> +obj-$(CONFIG_EDAC_ALTERA_OCRAM) += ocram.o
> diff --git a/arch/arm/mach-socfpga/ocram.c b/arch/arm/mach-socfpga/ocram.c
> new file mode 100644
> index 0000000..1f12a38
> --- /dev/null
> +++ b/arch/arm/mach-socfpga/ocram.c
> @@ -0,0 +1,97 @@
> +/*
> + * Copyright Altera Corporation (C) 2015. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
> + */
> +#include <linux/io.h>
> +#include <linux/genalloc.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +
> +#define ALTR_OCRAM_CLEAR_ECC 0x00000018
> +#define ALTR_OCRAM_ECC_EN 0x00000019
> +
> +static int __init socfpga_init_ocram_ecc(void)
> +{
> + struct device_node *np;
> + struct resource res;
> + u32 iram_addr;
> + void __iomem *mapped_ocr_edac_addr;
> + resource_size_t size;
> + struct gen_pool *gp;
> + int ret;
> +
> + /* Get the size of the on-chip RAM */
> + np = of_find_compatible_node(NULL, NULL, "mmio-sram");
> + if (!np) {
> + pr_err("%s: Unable to find mmio-sram in dtb\n", __func__);
> + return -ENODEV;
> + }
> +
> + ret = of_address_to_resource(np, 0, &res);
> + if (ret) {
> + of_node_put(np);
> + pr_err("%s: Problem getting SRAM address in dtb\n", __func__);
> + return -ENODEV;
> + }
> + size = resource_size(&res);
> + of_node_put(np);
> +
> + /* Find the OCRAM EDAC device tree node */
> + np = of_find_compatible_node(NULL, NULL, "altr,ocram-edac");
> + if (!np) {
> + pr_err("%s: Unable to find altr,ocram-edac\n", __func__);
> + return -ENODEV;
> + }
> +
> + mapped_ocr_edac_addr = of_iomap(np, 0);
> + if (!mapped_ocr_edac_addr) {
> + of_node_put(np);
> + pr_err("%s: Unable to map OCRAM ecc regs.\n", __func__);
> + return -ENODEV;
> + }
> +
> + gp = of_get_named_gen_pool(np, "iram", 0);
> + if (!gp) {
> + of_node_put(np);
> + pr_err("%s: OCRAM cannot find gen pool\n", __func__);
> + return -ENODEV;
> + }
> + of_node_put(np);
> +
> + iram_addr = gen_pool_alloc(gp, size / sizeof(size_t));
Why divide by sizeof(size_t) here? As far as I am aware, resource_size
gives you a size in bytes...
> + if (iram_addr == 0) {
> + pr_err("%s: cannot alloc from gen pool\n", __func__);
> + return -ENODEV;
> + }
> +
> + /* Clear any pending OCRAM ECC interrupts, then enable ECC */
> + writel(ALTR_OCRAM_CLEAR_ECC, mapped_ocr_edac_addr);
> + writel(ALTR_OCRAM_ECC_EN, mapped_ocr_edac_addr);
> +
> + memset((void *)iram_addr, 0, size);
...and here we write size bytes, not (size / sizeof(size_t)) bytes, so
we're poking memory we weren't allocated.
How is this memory mapped exactly? Is memset safe?
Thanks,
Mark.
> +
> + gen_pool_free(gp, iram_addr, size / sizeof(size_t));
> +
> + iounmap(mapped_ocr_edac_addr);
> +
> + return 0;
> +}
> +
> +static void __exit socfpga_exit_ocram_ecc(void)
> +{
> +}
> +
> +module_init(socfpga_init_ocram_ecc);
> +module_exit(socfpga_exit_ocram_ecc);
> --
> 1.7.9.5
>
>
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