Re: [PATCHv5 2/5] arm: socfpga: Enable OCRAM ECC on startup.

[Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>]

On Wed, Nov 12, 2014 at 12:14:20AM +0000, tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org wrote:
> From: Thor Thayer <tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org>
> 
> 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.
> 
> Signed-off-by: Thor Thayer <tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org>
> ---
> 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.
> ---
>  arch/arm/mach-socfpga/Makefile  |    1 +
>  arch/arm/mach-socfpga/core.h    |    1 +
>  arch/arm/mach-socfpga/ocram.c   |   90 +++++++++++++++++++++++++++++++++++++++
>  arch/arm/mach-socfpga/socfpga.c |    9 ++++
>  4 files changed, 101 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/core.h b/arch/arm/mach-socfpga/core.h
> index 385baba..f3eee32 100644
> --- a/arch/arm/mach-socfpga/core.h
> +++ b/arch/arm/mach-socfpga/core.h
> @@ -45,5 +45,6 @@ extern unsigned long cpu1start_addr;
>  #define SOCFPGA_SCU_VIRT_BASE   0xfffec000
>  
>  void socfpga_init_l2_ecc(void);
> +void socfpga_init_ocram_ecc(void);
>  
>  #endif
> diff --git a/arch/arm/mach-socfpga/ocram.c b/arch/arm/mach-socfpga/ocram.c
> new file mode 100644
> index 0000000..a83b34f
> --- /dev/null
> +++ b/arch/arm/mach-socfpga/ocram.c
> @@ -0,0 +1,90 @@
> +/*
> + * Copyright Altera Corporation (C) 2014. 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/of_platform.h>
> +
> +#define ALTR_OCRAM_CLEAR_ECC          0x00000018
> +#define ALTR_OCRAM_ECC_EN             0x00000019
> +
> +void socfpga_init_ocram_ecc(void)
> +{
> +	struct device_node *np;
> +	const __be32 *prop;

Please don't use accessors which return raw __be32s in drivers,
typically it's the wrong thing to do and leaves horrible bugs and/or
quirks that are painful to fix up.

> +	u32 ocr_edac_addr, iram_addr, len;
> +	void __iomem  *mapped_ocr_edac_addr;
> +	size_t size;
> +	struct gen_pool *gp;
> +
> +	np = of_find_compatible_node(NULL, NULL, "altr,ocram-edac");
> +	if (!np) {
> +		pr_err("SOCFPGA: Unable to find altr,ocram-edac in dtb\n");
> +		return;
> +	}
> +
> +	prop = of_get_property(np, "reg", &size);
> +	if (!prop || size < sizeof(*prop)) {
> +		pr_err("SOCFPGA: Unable to find OCRAM ECC mapping in dtb\n");
> +		return;
> +	}
> +	ocr_edac_addr = be32_to_cpup(prop++);
> +	len = be32_to_cpup(prop);

Use of_iomap(np, 0). You don't seem to pass the address around, so that
should be sufficient.

> +
> +	gp = of_get_named_gen_pool(np, "iram", 0);
> +	if (!gp) {
> +		pr_err("SOCFPGA: OCRAM cannot find gen pool\n");
> +		return;
> +	}
> +
> +	np = of_find_compatible_node(NULL, NULL, "mmio-sram");
> +	if (!np) {
> +		pr_err("SOCFPGA: Unable to find mmio-sram in dtb\n");
> +		return;
> +	}
> +
> +	/* Determine the OCRAM address and size */
> +	prop = of_get_property(np, "reg", &size);
> +	if (!prop || size < sizeof(*prop)) {
> +		pr_err("SOCFPGA: Unable to find OCRAM mapping in dtb\n");
> +		return;
> +	}
> +	iram_addr = be32_to_cpup(prop++);
> +	len = be32_to_cpup(prop);

This address is overwritten below. What's going on?

> +
> +	iram_addr = gen_pool_alloc(gp, len);
> +	if (iram_addr == 0) {
> +		pr_err("SOCFPGA: cannot alloc from gen pool\n");
> +		return;
> +	}
> +
> +	memset((void *)iram_addr, 0, len);

How is the iram mapped? Is memset to it safe (e.g. it unaligned accesses
are made)?

> +
> +	gen_pool_free(gp, iram_addr, len);
> +
> +	mapped_ocr_edac_addr = ioremap(ocr_edac_addr, 4);
> +	if (!mapped_ocr_edac_addr) {
> +		pr_err("SOCFPGA: Unable to map OCRAM ecc regs.\n");
> +		return;
> +	}
> +
> +	/* 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);
> +
> +	iounmap(mapped_ocr_edac_addr);
> +
> +	pr_debug("SOCFPGA: Success Initializing OCRAM\n");
> +}
> diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
> index 0954011..065d80d 100644
> --- a/arch/arm/mach-socfpga/socfpga.c
> +++ b/arch/arm/mach-socfpga/socfpga.c
> @@ -100,6 +100,14 @@ static void socfpga_cyclone5_restart(enum reboot_mode mode, const char *cmd)
>  	writel(temp, rst_manager_base_addr + SOCFPGA_RSTMGR_CTRL);
>  }
>  
> +static void __init socfpga_cyclone5_init(void)
> +{
> +	of_platform_populate(NULL, of_default_bus_match_table,
> +			     NULL, NULL);
> +	if (IS_ENABLED(CONFIG_EDAC_ALTERA_OCRAM))
> +		socfpga_init_ocram_ecc();

If it's safe to do this after probing everything else, why can't this be
a normal device probe?

Thanks,
Mark.
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