Re: [PATCH v9 2/2] EDAC: add EDAC driver for DMC520

From: Borislav Petkov
Date: Thu Jan 16 2020 - 19:18:59 EST

On Wed, Jan 15, 2020 at 06:32:33AM -0800, Shiping Ji wrote:
> New driver supports error detection and correction on the devices with ARM
> DMC-520 memory controller.
>
> Signed-off-by: Shiping Ji <shiping.linux@xxxxxxxxx>
> Signed-off-by: Lei Wang <leiwang_git@xxxxxxxxxxx>
> Reviewed-by: James Morse <james.morse@xxxxxxx>
>
> ---
> Changes in v9:
> - Removed interrupt-config and replaced with an interrupt map where names and masks are predefined
> - Only one ISR function is defined, mask is retrieved from the interrupt map
> - "dram_ecc_errc" and "dram_ecc_errd" are implemented
>
> ---
> MAINTAINERS | 6 +
> drivers/edac/Kconfig | 7 +
> drivers/edac/Makefile | 1 +
> drivers/edac/dmc520_edac.c | 670 +++++++++++++++++++++++++++++++++++++
> 4 files changed, 684 insertions(+)
> create mode 100644 drivers/edac/dmc520_edac.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bd5847e802de..386195a019c6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5914,6 +5914,12 @@ F: Documentation/driver-api/edac.rst
> F: drivers/edac/
> F: include/linux/edac.h
>
> +EDAC-DMC520
> +M: Lei Wang <lewan@xxxxxxxxxxxxx>
> +L: linux-edac@xxxxxxxxxxxxxxx
> +S: Supported
> +F: drivers/edac/dmc520_edac.c
> +
> EDAC-E752X
> M: Mark Gross <mark.gross@xxxxxxxxx>
> L: linux-edac@xxxxxxxxxxxxxxx
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 37027c298323..7305bd1ec80e 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -523,4 +523,11 @@ config EDAC_BLUEFIELD
> Support for error detection and correction on the
> Mellanox BlueField SoCs.
>
> +config EDAC_DMC520
> + tristate "ARM DMC-520 ECC"
> + depends on ARM64
> + help
> + Support for error detection and correction on the
> + SoCs with ARM DMC-520 DRAM controller.
> +
> endif # EDAC
> diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
> index d77200c9680b..269e15118cea 100644
> --- a/drivers/edac/Makefile
> +++ b/drivers/edac/Makefile
> @@ -87,3 +87,4 @@ obj-$(CONFIG_EDAC_TI) += ti_edac.o
> obj-$(CONFIG_EDAC_QCOM) += qcom_edac.o
> obj-$(CONFIG_EDAC_ASPEED) += aspeed_edac.o
> obj-$(CONFIG_EDAC_BLUEFIELD) += bluefield_edac.o
> +obj-$(CONFIG_EDAC_DMC520) += dmc520_edac.o
> diff --git a/drivers/edac/dmc520_edac.c b/drivers/edac/dmc520_edac.c
> new file mode 100644
> index 000000000000..55237c5c522c
> --- /dev/null
> +++ b/drivers/edac/dmc520_edac.c
> @@ -0,0 +1,670 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * EDAC driver for DMC-520 memory controller.
> + *
> + * The driver supports 10 interrupt lines,
> + * though only dram_ecc_errc and dram_ecc_errd are currently handled.
> + *
> + * Authors: Rui Zhao <ruizhao@xxxxxxxxxxxxx>
> + * Lei Wang <lewan@xxxxxxxxxxxxx>
> + * Shiping Ji <shji@xxxxxxxxxxxxx>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/edac.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include "edac_mc.h"
> +
> +/* DMC-520 registers */
> +#define REG_OFFSET_FEATURE_CONFIG 0x130
> +#define REG_OFFSET_ECC_ERRC_COUNT_31_00 0x158
> +#define REG_OFFSET_ECC_ERRC_COUNT_63_32 0x15C
> +#define REG_OFFSET_ECC_ERRD_COUNT_31_00 0x160
> +#define REG_OFFSET_ECC_ERRD_COUNT_63_32 0x164
> +#define REG_OFFSET_INTERRUPT_CONTROL 0x500
> +#define REG_OFFSET_INTERRUPT_CLR 0x508
> +#define REG_OFFSET_INTERRUPT_STATUS 0x510
> +#define REG_OFFSET_DRAM_ECC_ERRC_INT_INFO_31_00 0x528
> +#define REG_OFFSET_DRAM_ECC_ERRC_INT_INFO_63_32 0x52C
> +#define REG_OFFSET_DRAM_ECC_ERRD_INT_INFO_31_00 0x530
> +#define REG_OFFSET_DRAM_ECC_ERRD_INT_INFO_63_32 0x534
> +#define REG_OFFSET_ADDRESS_CONTROL_NOW 0x1010
> +#define REG_OFFSET_MEMORY_TYPE_NOW 0x1128
> +#define REG_OFFSET_SCRUB_CONTROL0_NOW 0x1170
> +#define REG_OFFSET_FORMAT_CONTROL 0x18
> +
> +/* DMC-520 types, masks and bitfields */
> +#define RAM_ECC_INT_CE_BIT BIT(0)
> +#define RAM_ECC_INT_UE_BIT BIT(1)
> +#define DRAM_ECC_INT_CE_BIT BIT(2)
> +#define DRAM_ECC_INT_UE_BIT BIT(3)
> +#define FAILED_ACCESS_INT_BIT BIT(4)
> +#define FAILED_PROG_INT_BIT BIT(5)
> +#define LINK_ERR_INT_BIT BIT(6)
> +#define TEMPERATURE_EVENT_INT_BIT BIT(7)

Align values vertically.

> +#define ARCH_FSM_INT_BIT BIT(8)
> +#define PHY_REQUEST_INT_BIT BIT(9)
> +#define MEMORY_WIDTH_MASK GENMASK(1, 0)
> +#define SCRUB_TRIGGER0_NEXT_MASK GENMASK(1, 0)
> +#define REG_FIELD_DRAM_ECC_ENABLED GENMASK(1, 0)
> +#define REG_FIELD_MEMORY_TYPE GENMASK(2, 0)
> +#define REG_FIELD_DEVICE_WIDTH GENMASK(9, 8)
> +#define REG_FIELD_ADDRESS_CONTROL_COL GENMASK(2, 0)
> +#define REG_FIELD_ADDRESS_CONTROL_ROW GENMASK(10, 8)
> +#define REG_FIELD_ADDRESS_CONTROL_BANK GENMASK(18, 16)
> +#define REG_FIELD_ADDRESS_CONTROL_RANK GENMASK(25, 24)
> +#define REG_FIELD_ERR_INFO_LOW_VALID BIT(0)
> +#define REG_FIELD_ERR_INFO_LOW_COL GENMASK(10, 1)
> +#define REG_FIELD_ERR_INFO_LOW_ROW GENMASK(28, 11)
> +#define REG_FIELD_ERR_INFO_LOW_RANK GENMASK(31, 29)
> +#define REG_FIELD_ERR_INFO_HIGH_BANK GENMASK(3, 0)
> +#define REG_FIELD_ERR_INFO_HIGH_VALID BIT(31)
> +
> +#define DRAM_ADDRESS_CONTROL_MIN_COL_BITS 8
> +#define DRAM_ADDRESS_CONTROL_MIN_ROW_BITS 11
> +
> +#define DMC520_SCRUB_TRIGGER_ERR_DETECT 2
> +#define DMC520_SCRUB_TRIGGER_IDLE 3
> +
> +/* Driver settings */
> +/*
> + * The max-length message would be: "rank:7 bank:15 row:262143 col:1023".
> + * Max length is 34. Using a 40-size buffer is enough.
> + */
> +#define DMC520_MSG_BUF_SIZE 40
> +#define EDAC_MOD_NAME "dmc520-edac"
> +#define EDAC_CTL_NAME "dmc520"
> +
> +/* the data bus width for the attached memory chips. */
> +enum dmc520_mem_width {
> + MEM_WIDTH_X32 = 2,
> + MEM_WIDTH_X64 = 3
> +};
> +
> +/* memory type */
> +enum dmc520_mem_type {
> + MEM_TYPE_DDR3 = 1,
> + MEM_TYPE_DDR4 = 2
> +};
> +
> +/* memory device width */
> +enum dmc520_dev_width {
> + DEV_WIDTH_X4 = 0,
> + DEV_WIDTH_X8 = 1,
> + DEV_WIDTH_X16 = 2
> +};
> +
> +struct ecc_error_info {
> + u32 col;
> + u32 row;
> + u32 bank;
> + u32 rank;
> +};
> +
> +/* The interrupt config */
> +struct dmc520_irq_config {
> + char *name;
> + int mask;
> +};
> +
> +/* The interrupt mappings */
> +static struct dmc520_irq_config dmc520_irq_configs[] = {
> + {

Just a nit:

ERROR: trailing whitespace
#209: FILE: drivers/edac/dmc520_edac.c:119:
+^I{ $

IOW, before you send next time, do:

$ git log -p -1 | ./scripts/checkpatch.pl

to verify you've caught them all.

> + .name = "ram_ecc_errc",
> + .mask = RAM_ECC_INT_CE_BIT
> + },
> + {
> + .name = "ram_ecc_errd",
> + .mask = RAM_ECC_INT_UE_BIT
> + },
> + {
> + .name = "dram_ecc_errc",
> + .mask = DRAM_ECC_INT_CE_BIT
> + },
> + {
> + .name = "dram_ecc_errd",
> + .mask = DRAM_ECC_INT_UE_BIT
> + },
> + {
> + .name = "failed_access",
> + .mask = FAILED_ACCESS_INT_BIT
> + },
> + {
> + .name = "failed_prog",
> + .mask = FAILED_PROG_INT_BIT
> + },
> + {
> + .name = "link_err",
> + .mask = LINK_ERR_INT_BIT
> + },
> + {
> + .name = "temperature_event",
> + .mask = TEMPERATURE_EVENT_INT_BIT
> + },
> + {
> + .name = "arch_fsm",
> + .mask = ARCH_FSM_INT_BIT
> + },
> + {
> + .name = "phy_request",
> + .mask = PHY_REQUEST_INT_BIT
> + }
> +};
> +
> +#define NUMBER_OF_IRQS ARRAY_SIZE(dmc520_irq_configs)

WARNING: please, no space before tabs
#251: FILE: drivers/edac/dmc520_edac.c:161:
+#define NUMBER_OF_IRQS ^I^I^I^IARRAY_SIZE(dmc520_irq_configs)$

> +
> +/* The EDAC driver private data */
> +struct dmc520_edac {
> + void __iomem *reg_base;
> + spinlock_t ecc_lock;

What does that spinlock protect? Also, its name is not very optimal.

> + int irqs[NUMBER_OF_IRQS];
> + int masks[NUMBER_OF_IRQS];
> +};
> +
> +static int dmc520_mc_idx;
> +
> +static irqreturn_t
> +dmc520_edac_dram_all_isr(int irq, struct mem_ctl_info *mci, u32 irq_mask);

Move the ISR under dmc520_edac_dram_all_isr() and get rid of that
forward declaration.

> +
> +static irqreturn_t dmc520_isr(int irq, void *data)
> +{
> + struct mem_ctl_info *mci;
> + struct dmc520_edac *edac;
> + int idx;
> + u32 mask = 0;
> + mci = data;

WARNING: Missing a blank line after declarations
#272: FILE: drivers/edac/dmc520_edac.c:182:
+ u32 mask = 0;
+ mci = data;

> + edac = mci->pvt_info;

Also, do this:

struct mem_ctl_info *mci = data;
struct dmc520_edac *pvt = mci->pvt_info;
u32 mask = 0;
int idx;


> +
> + for (idx = 0; idx < NUMBER_OF_IRQS; idx++) {
> + if (edac->irqs[idx] == irq) {
> + mask = edac->masks[idx];
> + break;
> + }
> + }
> + return dmc520_edac_dram_all_isr(irq, mci, mask);
> +}
> +
> +static u32 dmc520_read_reg(struct dmc520_edac *edac, u32 offset)
> +{
> + return readl(edac->reg_base + offset);
> +}
> +
> +static void dmc520_write_reg(struct dmc520_edac *edac, u32 val, u32 offset)
> +{
> + writel(val, edac->reg_base + offset);
> +}
> +
> +static u32 dmc520_calc_dram_ecc_error(u32 value)
> +{
> + u32 total = 0;
> +
> + /* Each rank's error counter takes one byte. */
> + while (value > 0) {
> + total += (value & 0xFF);
> + value >>= 8;
> + }
> + return total;
> +}
> +
> +static u32 dmc520_get_dram_ecc_error_count(struct dmc520_edac *edac,
> + bool is_ce)
> +{
> + u32 reg_offset_low, reg_offset_high;
> + u32 err_low, err_high;
> + u32 err_count;
> +
> + reg_offset_low = is_ce ? REG_OFFSET_ECC_ERRC_COUNT_31_00 :
> + REG_OFFSET_ECC_ERRD_COUNT_31_00;
> + reg_offset_high = is_ce ? REG_OFFSET_ECC_ERRC_COUNT_63_32 :
> + REG_OFFSET_ECC_ERRD_COUNT_63_32;
> +
> + err_low = dmc520_read_reg(edac, reg_offset_low);
> + err_high = dmc520_read_reg(edac, reg_offset_high);
> + /* Reset error counters */
> + dmc520_write_reg(edac, 0, reg_offset_low);
> + dmc520_write_reg(edac, 0, reg_offset_high);
> +
> + err_count = dmc520_calc_dram_ecc_error(err_low) +
> + dmc520_calc_dram_ecc_error(err_high);
> +
> + return err_count;
> +}
> +
> +static void dmc520_get_dram_ecc_error_info(struct dmc520_edac *edac,
> + bool is_ce,
> + struct ecc_error_info *info)
> +{
> + u32 reg_offset_low, reg_offset_high;
> + u32 reg_val_low, reg_val_high;
> + bool valid;
> +
> + reg_offset_low = is_ce ? REG_OFFSET_DRAM_ECC_ERRC_INT_INFO_31_00 :
> + REG_OFFSET_DRAM_ECC_ERRD_INT_INFO_31_00;
> + reg_offset_high = is_ce ? REG_OFFSET_DRAM_ECC_ERRC_INT_INFO_63_32 :
> + REG_OFFSET_DRAM_ECC_ERRD_INT_INFO_63_32;

Those define names could be shorter.

> +
> + reg_val_low = dmc520_read_reg(edac, reg_offset_low);
> + reg_val_high = dmc520_read_reg(edac, reg_offset_high);
> +
> + valid = (FIELD_GET(REG_FIELD_ERR_INFO_LOW_VALID, reg_val_low) != 0) &&
> + (FIELD_GET(REG_FIELD_ERR_INFO_HIGH_VALID, reg_val_high) != 0);
> +
> + if (valid) {
> + info->col =
> + FIELD_GET(REG_FIELD_ERR_INFO_LOW_COL, reg_val_low);
> + info->row =
> + FIELD_GET(REG_FIELD_ERR_INFO_LOW_ROW, reg_val_low);
> + info->rank =
> + FIELD_GET(REG_FIELD_ERR_INFO_LOW_RANK, reg_val_low);
> + info->bank =
> + FIELD_GET(REG_FIELD_ERR_INFO_HIGH_BANK, reg_val_high);

Those too.

And let those stick out - the 80 cols rule is not an absolute one.

> + } else {
> + memset(info, 0, sizeof(struct ecc_error_info));
> + }
> +}
> +
> +static bool dmc520_is_ecc_enabled(void __iomem *reg_base)
> +{
> + u32 reg_val = readl(reg_base + REG_OFFSET_FEATURE_CONFIG);
> +
> + return FIELD_GET(REG_FIELD_DRAM_ECC_ENABLED, reg_val);
> +}
> +
> +static enum scrub_type dmc520_get_scrub_type(struct dmc520_edac *edac)
> +{
> + enum scrub_type type = SCRUB_NONE;
> + u32 reg_val, scrub_cfg;
> +
> + reg_val = dmc520_read_reg(edac, REG_OFFSET_SCRUB_CONTROL0_NOW);
> + scrub_cfg = FIELD_GET(SCRUB_TRIGGER0_NEXT_MASK, reg_val);
> +
> + if (scrub_cfg == DMC520_SCRUB_TRIGGER_ERR_DETECT ||
> + scrub_cfg == DMC520_SCRUB_TRIGGER_IDLE)
> + type = SCRUB_HW_PROG;
> +
> + return type;
> +}
> +
> +/* Get the memory data bus width, in number of bytes. */
> +static u32 dmc520_get_memory_width(struct dmc520_edac *edac)
> +{
> + enum dmc520_mem_width mem_width_field;
> + static u32 mem_width_in_bytes;
> + u32 reg_val;
> +
> + if (mem_width_in_bytes)
> + return mem_width_in_bytes;

This looks like the memory width in bytes is the same for the whole
device so you can do this determination in the probe function and make
that mem_width_in_bytes variable global and define it at the beginning
of this file.

> + reg_val = dmc520_read_reg(edac, REG_OFFSET_FORMAT_CONTROL);
> + mem_width_field = FIELD_GET(MEMORY_WIDTH_MASK, reg_val);
> +
> + if (mem_width_field == MEM_WIDTH_X32)
> + mem_width_in_bytes = 4;
> + else if (mem_width_field == MEM_WIDTH_X64)
> + mem_width_in_bytes = 8;
> + return mem_width_in_bytes;
> +}

...

> +
> +static int dmc520_edac_probe(struct platform_device *pdev)
> +{
> + bool registered[NUMBER_OF_IRQS] = {false};
> + int irqs[NUMBER_OF_IRQS] = {-ENXIO};
> + int masks[NUMBER_OF_IRQS] = {0};

Add spaces around those initializers. E.g., { -ENXIO }; etc.

> + struct mem_ctl_info *mci = NULL;

Useless initialization.

> + struct edac_mc_layer layers[1];
> + struct dmc520_edac *edac;

drivers/edac/dmc520_edac.c: In function âdmc520_edac_probeâ:
drivers/edac/dmc520_edac.c:493:22: warning: âedacâ may be used uninitialized in this function [-Wmaybe-uninitialized]
struct dmc520_edac *edac;
^~~~

Also, that variable name is a bad choice. Most drivers call it "pvt" or
so to mean, driver's "private data".

> + void __iomem *reg_base;
> + u32 irq_mask_all = 0;
> + int ret, idx, irq;
> + struct resource *res;
> + struct device *dev;
> + u32 reg_val;
> +
> + /* Parse the device node */
> + dev = &pdev->dev;
> +
> + for (idx = 0; idx < NUMBER_OF_IRQS; idx++) {
> + irq = platform_get_irq_byname(pdev, dmc520_irq_configs[idx].name);
> + irqs[idx] = irq;
> + masks[idx] = dmc520_irq_configs[idx].mask;
> + if (irq >= 0) {
> + irq_mask_all |= dmc520_irq_configs[idx].mask;
> + edac_printk(KERN_INFO, EDAC_MOD_NAME,
> + "Discovered %s, irq: %d.\n", dmc520_irq_configs[idx].name, irq);

Is that something you really wanna say on driver load? I.e., should it
be edac_dbg() ?

> + }
> + }
> +
> + if (irq_mask_all == 0) {

if (!irq_mask_all)

> + edac_printk(KERN_ERR, EDAC_MOD_NAME,
> + "At least one valid interrupt line is expected.\n");
> + return -EINVAL;
> + }
> +
> + /* Initialize dmc520 edac */
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + reg_base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(reg_base))
> + return PTR_ERR(reg_base);
> +
> + if (!dmc520_is_ecc_enabled(reg_base))
> + return -ENXIO;
> +
> + layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
> + layers[0].size = dmc520_get_rank_count(reg_base);
> + layers[0].is_virt_csrow = true;
> +
> + mci = edac_mc_alloc(dmc520_mc_idx++, ARRAY_SIZE(layers), layers,
> + sizeof(struct dmc520_edac));
> + if (!mci) {
> + edac_printk(KERN_ERR, EDAC_MOD_NAME,
> + "Failed to allocate memory for mc instance\n");
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + edac = mci->pvt_info;
> +
> + edac->reg_base = reg_base;
> + spin_lock_init(&edac->ecc_lock);
> + memcpy(edac->irqs, irqs, sizeof(irqs));
> + memcpy(edac->masks, masks, sizeof(masks));
> +
> + platform_set_drvdata(pdev, mci);
> +
> + mci->pdev = dev;
> + mci->mtype_cap = MEM_FLAG_DDR3 | MEM_FLAG_DDR4;
> + mci->edac_ctl_cap = EDAC_FLAG_NONE | EDAC_FLAG_SECDED;
> + mci->edac_cap = EDAC_FLAG_SECDED;
> + mci->scrub_cap = SCRUB_FLAG_HW_SRC;
> + mci->scrub_mode = dmc520_get_scrub_type(edac);
> + mci->ctl_name = EDAC_CTL_NAME;
> + mci->dev_name = dev_name(mci->pdev);
> + mci->mod_name = EDAC_MOD_NAME;
> +
> + edac_op_state = EDAC_OPSTATE_INT;
> +
> + dmc520_init_csrow(mci);
> +
> + /* Clear interrupts, not affecting other unrelated interrupts */
> + reg_val = dmc520_read_reg(edac, REG_OFFSET_INTERRUPT_CONTROL);
> + dmc520_write_reg(edac, reg_val & (~irq_mask_all),
> + REG_OFFSET_INTERRUPT_CONTROL);
> + dmc520_write_reg(edac, irq_mask_all, REG_OFFSET_INTERRUPT_CLR);
> +
> + for (idx = 0; idx < NUMBER_OF_IRQS; idx++) {
> + irq = irqs[idx];
> + if (irq >= 0) {
> + ret = devm_request_irq(&pdev->dev, irq,
> + dmc520_isr, IRQF_SHARED,
> + dev_name(&pdev->dev), mci);

Align arguments on the opening brace.

> + if (ret < 0) {
> + edac_printk(KERN_ERR, EDAC_MC,
> + "Failed to request irq %d\n", irq);

Ditto.

> + goto err;
> + }
> + registered[idx] = true;
> + }
> + }
> +
> + /* Reset DRAM CE/UE counters */
> + if (irq_mask_all & DRAM_ECC_INT_CE_BIT)
> + dmc520_get_dram_ecc_error_count(edac, true);
> +
> + if (irq_mask_all & DRAM_ECC_INT_UE_BIT)
> + dmc520_get_dram_ecc_error_count(edac, false);
> +
> + ret = edac_mc_add_mc(mci);
> + if (ret) {
> + edac_printk(KERN_ERR, EDAC_MOD_NAME,
> + "Failed to register with EDAC core\n");
> + goto err;
> + }
> +
> + /* Enable interrupts, not affecting other unrelated interrupts */
> + dmc520_write_reg(edac, reg_val | irq_mask_all,
> + REG_OFFSET_INTERRUPT_CONTROL);
> +
> + return 0;
> +
> +err:
> + for (idx = 0; idx < NUMBER_OF_IRQS; idx++) {
> + if (registered[idx]) {
> + devm_free_irq(&pdev->dev, edac->irqs[idx], mci);
> + }

WARNING: braces {} are not necessary for single statement blocks
#699: FILE: drivers/edac/dmc520_edac.c:609:
+ if (registered[idx]) {
+ devm_free_irq(&pdev->dev, edac->irqs[idx], mci);
+ }

> + }
> + if (mci)
> + edac_mc_free(mci);
> +
> + return ret;
> +}
> +
> +static int dmc520_edac_remove(struct platform_device *pdev)
> +{
> + struct dmc520_edac *edac;
> + struct mem_ctl_info *mci;
> + u32 reg_val, idx, irq_mask_all = 0;

Please sort function local variables declaration in a reverse christmas
tree order:

<type A> longest_variable_name;
<type B> shorter_var_name;
<type C> even_shorter;
<type D> i;

> +
> + mci = platform_get_drvdata(pdev);
> + edac = mci->pvt_info;
> +
> + /* free irq's */
> + for (idx = 0; idx < NUMBER_OF_IRQS; idx++) {
> + if (edac->irqs[idx] >= 0) {
> + irq_mask_all |= edac->masks[idx];
> + devm_free_irq(&pdev->dev, edac->irqs[idx], mci);
> + }
> + }
> +
> + /* Disable interrupts */
> + reg_val = dmc520_read_reg(edac, REG_OFFSET_INTERRUPT_CONTROL);
> + dmc520_write_reg(edac, reg_val & (~irq_mask_all),
> + REG_OFFSET_INTERRUPT_CONTROL);

Huh, aren't you supposed to disable the interrupts and *then* free the
IRQs?

> +
> + edac_mc_del_mc(&pdev->dev);
> + edac_mc_free(mci);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id dmc520_edac_driver_id[] = {
> + { .compatible = "arm,dmc-520", },
> + { /* end of table */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, dmc520_edac_driver_id);
> +
> +static struct platform_driver dmc520_edac_driver = {
> + .driver = {
> + .name = "dmc520",
> + .of_match_table = dmc520_edac_driver_id,
> + },
> +
> + .probe = dmc520_edac_probe,
> + .remove = dmc520_edac_remove
> +};
> +
> +module_platform_driver(dmc520_edac_driver);
> +
> +MODULE_AUTHOR("Rui Zhao <ruizhao@xxxxxxxxxxxxx>");
> +MODULE_AUTHOR("Lei Wang <lewan@xxxxxxxxxxxxx>");
> +MODULE_AUTHOR("Shiping Ji <shji@xxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("DMC-520 ECC driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.17.1
>

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette