[PATCH 0/2] Add support for the Aspeed AST2500 SoC EDAC driver.

[PATCH 0/2] Add support for the Aspeed AST2500 SoC EDAC driver.

[Stefan Schaeckeler]

From: Stefan M Schaeckeler <schaecsn@gmx.net>

Add support for the Aspeed AST2500 SoC EDAC driver.

Note, I only have access to AST2500 hardware and documentation. The AST2500
documentation explicitly states that the sdram controller is not backward
compatible with AST2400 and hence this driver is not supporting it.

Best, Stefan


Stefan M Schaeckeler (2):
  EDAC: Add Aspeed AST2500 EDAC driver
  dt-bindings: edac: Aspeed AST2500

 .../bindings/edac/aspeed-sdram-edac.txt       |  34 ++
 MAINTAINERS                                   |   6 +
 arch/arm/boot/dts/aspeed-g5.dtsi              |   7 +
 drivers/edac/Kconfig                          |   7 +
 drivers/edac/Makefile                         |   1 +
 drivers/edac/aspeed_edac.c                    | 457 ++++++++++++++++++
 6 files changed, 512 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
 create mode 100644 drivers/edac/aspeed_edac.c

-- 
2.19.1


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[PATCH 1/2] EDAC: Add Aspeed AST2500 EDAC driver

[Stefan Schaeckeler]

From: Stefan M Schaeckeler <sschaeck@cisco.com>

Add support for the Aspeed AST2500 SoC EDAC driver.

Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
---
 MAINTAINERS                      |   6 +
 arch/arm/boot/dts/aspeed-g5.dtsi |   7 +
 drivers/edac/Kconfig             |   7 +
 drivers/edac/Makefile            |   1 +
 drivers/edac/aspeed_edac.c       | 457 +++++++++++++++++++++++++++++++
 5 files changed, 478 insertions(+)
 create mode 100644 drivers/edac/aspeed_edac.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 3318f30903b2..1feb92b14029 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5315,6 +5315,12 @@ L:	linux-edac@vger.kernel.org
 S:	Maintained
 F:	drivers/edac/amd64_edac*
 
+EDAC-AST2500
+M:	Stefan Schaeckeler <sschaeck@cisco.com>
+S:	Supported
+F:	drivers/edac/aspeed_edac.c
+F:	Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
+
 EDAC-CALXEDA
 M:	Robert Richter <rric@kernel.org>
 L:	linux-edac@vger.kernel.org
diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
index d107459fc0f8..b4e479ab5a2d 100644
--- a/arch/arm/boot/dts/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed-g5.dtsi
@@ -47,6 +47,13 @@
 		reg = <0x80000000 0>;
 	};
 
+	edac: sdram@1e6e0000 {
+		compatible = "aspeed,ast2500-sdram-edac";
+		reg = <0x1e6e0000 0x174>;
+		interrupts = <0>;
+		status = "disabled";
+	};
+
 	ahb {
 		compatible = "simple-bus";
 		#address-cells = <1>;
diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
index 41c9ccdd20d6..67834430b0a1 100644
--- a/drivers/edac/Kconfig
+++ b/drivers/edac/Kconfig
@@ -475,4 +475,11 @@ config EDAC_QCOM
 	  For debugging issues having to do with stability and overall system
 	  health, you should probably say 'Y' here.
 
+config EDAC_ASPEED
+	tristate "Aspeed AST 2500 SoC"
+	depends on MACH_ASPEED_G5
+	help
+	  Support for error detection and correction on the
+	  Aspeed AST 2500 SoC.
+
 endif # EDAC
diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
index 716096d08ea0..e1f23d4ff860 100644
--- a/drivers/edac/Makefile
+++ b/drivers/edac/Makefile
@@ -78,3 +78,4 @@ obj-$(CONFIG_EDAC_SYNOPSYS)		+= synopsys_edac.o
 obj-$(CONFIG_EDAC_XGENE)		+= xgene_edac.o
 obj-$(CONFIG_EDAC_TI)			+= ti_edac.o
 obj-$(CONFIG_EDAC_QCOM)			+= qcom_edac.o
+obj-$(CONFIG_EDAC_ASPEED)		+= aspeed_edac.o
diff --git a/drivers/edac/aspeed_edac.c b/drivers/edac/aspeed_edac.c
new file mode 100644
index 000000000000..d6ed119909eb
--- /dev/null
+++ b/drivers/edac/aspeed_edac.c
@@ -0,0 +1,457 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 Cisco Systems
+ *
+ * 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.
+ */
+
+#include <linux/edac.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/stop_machine.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+#include <asm/page.h>
+#include "edac_module.h"
+
+
+#define DRV_NAME "aspeed-edac"
+
+
+/* registers */
+#define ASPEED_MCR_PROT        0x00 /* protection key register */
+#define ASPEED_MCR_CONF        0x04 /* configuration register */
+#define ASPEED_MCR_INTR_CTRL   0x50 /* interrupt control/status register */
+#define ASPEED_MCR_ADDR_UNREC  0x58 /* address of first un-recoverable error */
+#define ASPEED_MCR_ADDR_REC    0x5c /* address of last recoverable error */
+#define ASPEED_MCR_LAST        ASPEED_MCR_ADDR_REC
+
+
+/* bits and masks */
+#define ASPEED_MCR_PROT_PASSWD	            0xfc600309
+#define ASPEED_MCR_CONF_DRAM_TYPE               BIT(4)
+#define ASPEED_MCR_CONF_ECC                     BIT(7)
+#define ASPEED_MCR_INTR_CTRL_CLEAR             BIT(31)
+#define ASPEED_MCR_INTR_CTRL_CNT_REC   GENMASK(23, 16)
+#define ASPEED_MCR_INTR_CTRL_CNT_UNREC GENMASK(15, 12)
+#define ASPEED_MCR_INTR_CTRL_ENABLE  (BIT(0) | BIT(1))
+
+
+
+static int aspeed_edac_regmap_reg_write(void *context, unsigned int reg,
+					unsigned int val)
+{
+	void __iomem *regs = (void __iomem *)context;
+
+	/* enable write to MCR register set */
+	writel(ASPEED_MCR_PROT_PASSWD, regs + ASPEED_MCR_PROT);
+
+	writel(val, regs + reg);
+
+	/* disable write to MCR register set */
+	writel(~ASPEED_MCR_PROT_PASSWD, regs + ASPEED_MCR_PROT);
+
+	return 0;
+}
+
+
+static int aspeed_edac_regmap_reg_read(void *context, unsigned int reg,
+				       unsigned int *val)
+{
+	void __iomem *regs = (void __iomem *)context;
+
+	*val = readl(regs + reg);
+
+	return 0;
+}
+
+static bool aspeed_edac_regmap_is_volatile(struct device *dev,
+					   unsigned int reg)
+{
+	switch (reg) {
+	case ASPEED_MCR_PROT:
+	case ASPEED_MCR_INTR_CTRL:
+	case ASPEED_MCR_ADDR_UNREC:
+	case ASPEED_MCR_ADDR_REC:
+		return true;
+	default:
+		return false;
+	}
+}
+
+
+static const struct regmap_config aspeed_edac_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = ASPEED_MCR_LAST,
+	.reg_write = aspeed_edac_regmap_reg_write,
+	.reg_read = aspeed_edac_regmap_reg_read,
+	.volatile_reg = aspeed_edac_regmap_is_volatile,
+	.fast_io = true,
+};
+
+
+static struct regmap *aspeed_edac_regmap;
+
+
+static void aspeed_edac_count_rec(struct mem_ctl_info *mci,
+				  u8 rec_cnt,
+				  u32 rec_addr)
+{
+	struct csrow_info *csrow = mci->csrows[0];
+	u32 page, offset, syndrome;
+
+	if (rec_cnt > 0) {
+		/* report first few errors (if there are) */
+		/* note: no addresses are recorded */
+		if (rec_cnt > 1) {
+			page = 0; /* not available */
+			offset = 0;  /* not available */
+			syndrome = 0; /* not available */
+			edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci,
+					     rec_cnt-1, page, offset,
+					     syndrome, 0, 0, -1,
+					     "address(es) not available", "");
+		}
+
+		/* report last error */
+		/* note: rec_addr is the last recoverable error addr */
+		page = rec_addr >> PAGE_SHIFT;
+		offset = rec_addr & ~PAGE_MASK;
+		syndrome = 0; /* not available */
+		edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci, 1,
+				     csrow->first_page + page, offset, syndrome,
+				     0, 0, -1, "", "");
+	}
+}
+
+
+static void aspeed_edac_count_un_rec(struct mem_ctl_info *mci,
+				     u8 un_rec_cnt,
+				     u32 un_rec_addr)
+{
+	struct csrow_info *csrow = mci->csrows[0];
+	u32 page, offset, syndrome;
+
+	if (un_rec_cnt > 0) {
+		/* report 1. error */
+		/* note: un_rec_addr is the first unrecoverable error addr */
+		page = un_rec_addr >> PAGE_SHIFT;
+		offset = un_rec_addr & ~PAGE_MASK;
+		syndrome = 0; /* not available */
+		edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci, 1,
+				     csrow->first_page + page, offset, syndrome,
+				     0, 0, -1, "", "");
+
+		/* report further errors (if there are) */
+		/* note: no addresses are recorded */
+		if (un_rec_cnt > 1) {
+			page = 0;  /* not available */
+			offset = 0;  /* not available */
+			syndrome = 0; /* not available */
+			edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci,
+					     un_rec_cnt-1, page, offset,
+					     syndrome, 0, 0, -1,
+					     "address(es) not available", "");
+		}
+	}
+}
+
+
+static void aspeed_edac_enable_interrupts(void)
+{
+
+	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
+			   ASPEED_MCR_INTR_CTRL_ENABLE,
+			   ASPEED_MCR_INTR_CTRL_ENABLE);
+}
+
+
+static void aspeed_edac_disable_interrupts(void)
+{
+	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
+			   ASPEED_MCR_INTR_CTRL_ENABLE, 0);
+}
+
+
+static void aspeed_edac_clear_interrupts(void)
+{
+	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
+			   ASPEED_MCR_INTR_CTRL_CLEAR,
+			   ASPEED_MCR_INTR_CTRL_CLEAR);
+
+	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
+			   ASPEED_MCR_INTR_CTRL_CLEAR, 0);
+}
+
+
+static irqreturn_t aspeed_edac_isr(int irq, void *arg)
+{
+	u8  rec_cnt, un_rec_cnt;
+	u32 rec_addr, un_rec_addr;
+	struct mem_ctl_info *mci = arg;
+	u32 reg50, reg5c, reg58;
+
+	regmap_read(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL, &reg50);
+	dev_dbg(mci->pdev, "received edac interrupt w/ mmc register 50: 0x%x\n",
+		reg50);
+
+	/* collect data about recoverable and unrecoverable errors */
+	rec_cnt = (reg50 & ASPEED_MCR_INTR_CTRL_CNT_REC) >> 16;
+	un_rec_cnt = (reg50 & ASPEED_MCR_INTR_CTRL_CNT_UNREC) >> 12;
+
+	dev_dbg(mci->pdev, "%d recoverable interrupts and %d unrecoverable interrupts\n",
+		rec_cnt, un_rec_cnt);
+
+	regmap_read(aspeed_edac_regmap, ASPEED_MCR_ADDR_UNREC, &reg58);
+	un_rec_addr = reg58 >> 4;
+
+	regmap_read(aspeed_edac_regmap, ASPEED_MCR_ADDR_REC, &reg5c);
+	rec_addr = reg5c >> 4;
+
+	/* clear interrupt flags and error counters: */
+	aspeed_edac_clear_interrupts();
+
+	/* process recoverable and unrecoverable errors */
+	if (rec_cnt > 0)
+		aspeed_edac_count_rec(mci, rec_cnt, rec_addr);
+
+	if (un_rec_cnt > 0)
+		aspeed_edac_count_un_rec(mci, un_rec_cnt, un_rec_addr);
+
+	if ((rec_cnt == 0) && (un_rec_cnt == 0))
+		dev_dbg(mci->pdev, "received edac interrupt, but did not find any ecc counters\n");
+
+	regmap_read(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL, &reg50);
+	dev_dbg(mci->pdev, "edac interrupt handled. mmc reg 50 is now: 0x%x\n",
+		reg50);
+
+	return IRQ_HANDLED;
+}
+
+
+static int aspeed_edac_config_irq(void *ctx,
+				  struct platform_device *pdev)
+{
+	int irq;
+	int rc;
+
+	/* register interrupt handler */
+
+	irq = platform_get_irq(pdev, 0);
+	dev_dbg(&pdev->dev, "got irq %d\n", irq);
+	if (!irq)
+		return -ENODEV;
+
+	rc = devm_request_irq(&pdev->dev, irq, aspeed_edac_isr,
+			      IRQF_TRIGGER_HIGH, DRV_NAME, ctx);
+	if (rc) {
+		dev_err(&pdev->dev, "unable to request irq %d\n", irq);
+		return rc;
+	}
+
+	/* enable interrupts */
+	aspeed_edac_enable_interrupts();
+
+	return 0;
+}
+
+
+static int aspeed_edac_init_csrows(struct mem_ctl_info *mci)
+{
+	struct csrow_info *csrow = mci->csrows[0];
+	struct dimm_info *dimm;
+	struct device_node *np;
+	u32 nr_pages, dram_type;
+	struct resource r;
+	u32 reg04;
+	int rc;
+
+	/* retrieve info about physical memory from device tree */
+	np = of_find_node_by_path("/memory");
+
+	if (!np) {
+		dev_err(mci->pdev, "dt: missing /memory node\n");
+		return -ENODEV;
+	};
+
+	rc = of_address_to_resource(np, 0, &r);
+
+	of_node_put(np);
+
+	if (rc) {
+		dev_err(mci->pdev, "dt: failed requesting resource for /memory node\n");
+		return rc;
+	};
+
+	dev_dbg(mci->pdev, "dt: /memory node resources: first page r.start=0x%x, resource_size=0x%x, PAGE_SHIFT macro=0x%x\n",
+		r.start, resource_size(&r), PAGE_SHIFT);
+
+	csrow->first_page = r.start >> PAGE_SHIFT;
+	nr_pages = resource_size(&r) >> PAGE_SHIFT;
+	csrow->last_page = csrow->first_page + nr_pages - 1;
+
+	regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
+	dram_type = (reg04 & ASPEED_MCR_CONF_DRAM_TYPE) ? MEM_DDR4 : MEM_DDR3;
+
+	dimm = csrow->channels[0]->dimm;
+	dimm->mtype = dram_type;
+	dimm->edac_mode = EDAC_SECDED;
+	dimm->nr_pages = nr_pages / csrow->nr_channels;
+
+	dev_dbg(mci->pdev, "initialized dimm with first_page=0x%lx and nr_pages=0x%x\n",
+		csrow->first_page, nr_pages);
+
+	return 0;
+}
+
+
+static int aspeed_edac_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	void __iomem *regs;
+	struct resource *res;
+	struct mem_ctl_info *mci;
+	struct edac_mc_layer layers[2];
+	struct device_node *np;
+	u32 reg04;
+	int rc;
+
+	/* setup regmap */
+	np = dev->of_node;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	aspeed_edac_regmap = devm_regmap_init(dev, NULL, (__force void *)regs,
+					       &aspeed_edac_regmap_config);
+	if (IS_ERR(aspeed_edac_regmap))
+		return PTR_ERR(aspeed_edac_regmap);
+
+	/* bail out if ECC mode is not configured */
+	regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
+	if (!(reg04 & ASPEED_MCR_CONF_ECC)) {
+		dev_err(&pdev->dev, "ECC mode is not configured in u-boot\n");
+		return -EPERM;
+	}
+
+	edac_op_state = EDAC_OPSTATE_INT;
+
+	/* allocate & init EDAC MC data structure */
+	layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
+	layers[0].size = 1;
+	layers[0].is_virt_csrow = true;
+	layers[1].type = EDAC_MC_LAYER_CHANNEL;
+	layers[1].size = 1;
+	layers[1].is_virt_csrow = false;
+
+	mci = edac_mc_alloc(0, ARRAY_SIZE(layers), layers, 0);
+	if (mci == NULL)
+		return -ENOMEM;
+
+	mci->pdev = &pdev->dev;
+	mci->mtype_cap = MEM_FLAG_DDR3 | MEM_FLAG_DDR4;
+	mci->edac_ctl_cap = EDAC_FLAG_SECDED;
+	mci->edac_cap = EDAC_FLAG_SECDED;
+	mci->scrub_cap = SCRUB_FLAG_HW_SRC;
+	mci->scrub_mode = SCRUB_HW_SRC;
+	mci->mod_name = DRV_NAME;
+	mci->ctl_name = "MIC";
+	mci->dev_name = dev_name(&pdev->dev);
+
+	rc = aspeed_edac_init_csrows(mci);
+	if (rc) {
+		dev_err(&pdev->dev, "failed to init csrows\n");
+		goto probe_exit02;
+	}
+
+	platform_set_drvdata(pdev, mci);
+
+	/* register with edac core */
+	rc = edac_mc_add_mc(mci);
+	if (rc) {
+		dev_err(&pdev->dev, "failed to register with EDAC core\n");
+		goto probe_exit02;
+	}
+
+	/* register interrupt handler and enable interrupts */
+	rc = aspeed_edac_config_irq(mci, pdev);
+	if (rc) {
+		dev_err(&pdev->dev, "failed setting up irq\n");
+		goto probe_exit01;
+	}
+
+	return 0;
+
+probe_exit01:
+	edac_mc_del_mc(&pdev->dev);
+probe_exit02:
+	edac_mc_free(mci);
+	return rc;
+}
+
+
+static int aspeed_edac_remove(struct platform_device *pdev)
+{
+	struct mem_ctl_info *mci;
+
+	/* disable interrupts */
+	aspeed_edac_disable_interrupts();
+
+	/* free resources */
+	mci = edac_mc_del_mc(&pdev->dev);
+	if (mci)
+		edac_mc_free(mci);
+
+	return 0;
+}
+
+
+static const struct of_device_id aspeed_edac_of_match[] = {
+	{ .compatible = "aspeed,ast2500-sdram-edac" },
+	{},
+};
+
+
+static struct platform_driver aspeed_edac_driver = {
+	.driver		= {
+		.name	= DRV_NAME,
+		.of_match_table = aspeed_edac_of_match
+	},
+	.probe		= aspeed_edac_probe,
+	.remove		= aspeed_edac_remove
+};
+
+
+static int __init aspeed_edac_init(void)
+{
+	return platform_driver_register(&aspeed_edac_driver);
+}
+
+
+static void __exit aspeed_edac_exit(void)
+{
+	platform_driver_unregister(&aspeed_edac_driver);
+}
+
+
+module_init(aspeed_edac_init);
+module_exit(aspeed_edac_exit);
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefan Schaeckeler <sschaeck@cisco.com>");
+MODULE_DESCRIPTION("Aspeed AST2500 EDAC driver");
+MODULE_VERSION("1.0");
-- 
2.19.1


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Re: [PATCH 1/2] EDAC: Add Aspeed AST2500 EDAC driver

[Stefan Schaeckeler]

Let me start with reviewing my own driver. Perhaps someone could review it as well, please?

I found a cosmetic issue and a bug. See inline.


> From:   Stefan Schaeckeler <schaecsn@gmx.net>
> 
> From: Stefan M Schaeckeler <sschaeck@cisco.com>
> 
> Add support for the Aspeed AST2500 SoC EDAC driver.
> 
> Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
> ---
>  MAINTAINERS                      |   6 +
>  arch/arm/boot/dts/aspeed-g5.dtsi |   7 +
>  drivers/edac/Kconfig             |   7 +
>  drivers/edac/Makefile            |   1 +
>  drivers/edac/aspeed_edac.c       | 457 +++++++++++++++++++++++++++++++
>  5 files changed, 478 insertions(+)
>  create mode 100644 drivers/edac/aspeed_edac.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3318f30903b2..1feb92b14029 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5315,6 +5315,12 @@ L:	linux-edac@vger.kernel.org
>  S:	Maintained
>  F:	drivers/edac/amd64_edac*
>  
> +EDAC-AST2500
> +M:	Stefan Schaeckeler <sschaeck@cisco.com>
> +S:	Supported
> +F:	drivers/edac/aspeed_edac.c
> +F:	Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> +
>  EDAC-CALXEDA
>  M:	Robert Richter <rric@kernel.org>
>  L:	linux-edac@vger.kernel.org
> diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
> index d107459fc0f8..b4e479ab5a2d 100644
> --- a/arch/arm/boot/dts/aspeed-g5.dtsi
> +++ b/arch/arm/boot/dts/aspeed-g5.dtsi
> @@ -47,6 +47,13 @@
>  		reg = <0x80000000 0>;
>  	};
>  
> +	edac: sdram@1e6e0000 {
> +		compatible = "aspeed,ast2500-sdram-edac";
> +		reg = <0x1e6e0000 0x174>;
> +		interrupts = <0>;
> +		status = "disabled";
> +	};
> +
>  	ahb {
>  		compatible = "simple-bus";
>  		#address-cells = <1>;
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 41c9ccdd20d6..67834430b0a1 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -475,4 +475,11 @@ config EDAC_QCOM
>  	  For debugging issues having to do with stability and overall system
>  	  health, you should probably say 'Y' here.
>  
> +config EDAC_ASPEED
> +	tristate "Aspeed AST 2500 SoC"
> +	depends on MACH_ASPEED_G5
> +	help
> +	  Support for error detection and correction on the
> +	  Aspeed AST 2500 SoC.
> +
>  endif # EDAC
> diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
> index 716096d08ea0..e1f23d4ff860 100644
> --- a/drivers/edac/Makefile
> +++ b/drivers/edac/Makefile
> @@ -78,3 +78,4 @@ obj-$(CONFIG_EDAC_SYNOPSYS)		+= synopsys_edac.o
>  obj-$(CONFIG_EDAC_XGENE)		+= xgene_edac.o
>  obj-$(CONFIG_EDAC_TI)			+= ti_edac.o
>  obj-$(CONFIG_EDAC_QCOM)			+= qcom_edac.o
> +obj-$(CONFIG_EDAC_ASPEED)		+= aspeed_edac.o
> diff --git a/drivers/edac/aspeed_edac.c b/drivers/edac/aspeed_edac.c
> new file mode 100644
> index 000000000000..d6ed119909eb
> --- /dev/null
> +++ b/drivers/edac/aspeed_edac.c
> @@ -0,0 +1,457 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2018 Cisco Systems
> + *
> + * 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.
> + */
> +
> +#include <linux/edac.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/stop_machine.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/regmap.h>
> +#include <asm/page.h>

Including asm/page.h does not seem to be necessary.


> +#include "edac_module.h"
> +
> +
> +#define DRV_NAME "aspeed-edac"
> +
> +
> +/* registers */
> +#define ASPEED_MCR_PROT        0x00 /* protection key register */
> +#define ASPEED_MCR_CONF        0x04 /* configuration register */
> +#define ASPEED_MCR_INTR_CTRL   0x50 /* interrupt control/status register */
> +#define ASPEED_MCR_ADDR_UNREC  0x58 /* address of first un-recoverable error */
> +#define ASPEED_MCR_ADDR_REC    0x5c /* address of last recoverable error */
> +#define ASPEED_MCR_LAST        ASPEED_MCR_ADDR_REC
> +
> +
> +/* bits and masks */
> +#define ASPEED_MCR_PROT_PASSWD	            0xfc600309
> +#define ASPEED_MCR_CONF_DRAM_TYPE               BIT(4)
> +#define ASPEED_MCR_CONF_ECC                     BIT(7)
> +#define ASPEED_MCR_INTR_CTRL_CLEAR             BIT(31)
> +#define ASPEED_MCR_INTR_CTRL_CNT_REC   GENMASK(23, 16)
> +#define ASPEED_MCR_INTR_CTRL_CNT_UNREC GENMASK(15, 12)
> +#define ASPEED_MCR_INTR_CTRL_ENABLE  (BIT(0) | BIT(1))
> +
> +
> +
> +static int aspeed_edac_regmap_reg_write(void *context, unsigned int reg,
> +					unsigned int val)
> +{
> +	void __iomem *regs = (void __iomem *)context;
> +
> +	/* enable write to MCR register set */
> +	writel(ASPEED_MCR_PROT_PASSWD, regs + ASPEED_MCR_PROT);
> +
> +	writel(val, regs + reg);
> +
> +	/* disable write to MCR register set */
> +	writel(~ASPEED_MCR_PROT_PASSWD, regs + ASPEED_MCR_PROT);
> +
> +	return 0;
> +}
> +
> +
> +static int aspeed_edac_regmap_reg_read(void *context, unsigned int reg,
> +				       unsigned int *val)
> +{
> +	void __iomem *regs = (void __iomem *)context;
> +
> +	*val = readl(regs + reg);
> +
> +	return 0;
> +}
> +
> +static bool aspeed_edac_regmap_is_volatile(struct device *dev,
> +					   unsigned int reg)
> +{
> +	switch (reg) {
> +	case ASPEED_MCR_PROT:
> +	case ASPEED_MCR_INTR_CTRL:
> +	case ASPEED_MCR_ADDR_UNREC:
> +	case ASPEED_MCR_ADDR_REC:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +
> +static const struct regmap_config aspeed_edac_regmap_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = ASPEED_MCR_LAST,
> +	.reg_write = aspeed_edac_regmap_reg_write,
> +	.reg_read = aspeed_edac_regmap_reg_read,
> +	.volatile_reg = aspeed_edac_regmap_is_volatile,
> +	.fast_io = true,
> +};
> +
> +
> +static struct regmap *aspeed_edac_regmap;
> +
> +
> +static void aspeed_edac_count_rec(struct mem_ctl_info *mci,
> +				  u8 rec_cnt,
> +				  u32 rec_addr)
> +{
> +	struct csrow_info *csrow = mci->csrows[0];
> +	u32 page, offset, syndrome;
> +
> +	if (rec_cnt > 0) {
> +		/* report first few errors (if there are) */
> +		/* note: no addresses are recorded */
> +		if (rec_cnt > 1) {
> +			page = 0; /* not available */
> +			offset = 0;  /* not available */
> +			syndrome = 0; /* not available */
> +			edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci,
> +					     rec_cnt-1, page, offset,
> +					     syndrome, 0, 0, -1,
> +					     "address(es) not available", "");
> +		}
> +
> +		/* report last error */
> +		/* note: rec_addr is the last recoverable error addr */
> +		page = rec_addr >> PAGE_SHIFT;
> +		offset = rec_addr & ~PAGE_MASK;
> +		syndrome = 0; /* not available */
> +		edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci, 1,
> +				     csrow->first_page + page, offset, syndrome,
> +				     0, 0, -1, "", "");
> +	}
> +}
> +
> +
> +static void aspeed_edac_count_un_rec(struct mem_ctl_info *mci,
> +				     u8 un_rec_cnt,
> +				     u32 un_rec_addr)
> +{
> +	struct csrow_info *csrow = mci->csrows[0];
> +	u32 page, offset, syndrome;
> +
> +	if (un_rec_cnt > 0) {
> +		/* report 1. error */
> +		/* note: un_rec_addr is the first unrecoverable error addr */
> +		page = un_rec_addr >> PAGE_SHIFT;
> +		offset = un_rec_addr & ~PAGE_MASK;
> +		syndrome = 0; /* not available */
> +		edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci, 1,
> +				     csrow->first_page + page, offset, syndrome,
> +				     0, 0, -1, "", "");
> +
> +		/* report further errors (if there are) */
> +		/* note: no addresses are recorded */
> +		if (un_rec_cnt > 1) {
> +			page = 0;  /* not available */
> +			offset = 0;  /* not available */
> +			syndrome = 0; /* not available */
> +			edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci,
> +					     un_rec_cnt-1, page, offset,
> +					     syndrome, 0, 0, -1,
> +					     "address(es) not available", "");
> +		}
> +	}
> +}
> +
> +
> +static void aspeed_edac_enable_interrupts(void)
> +{
> +
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_ENABLE,
> +			   ASPEED_MCR_INTR_CTRL_ENABLE);
> +}
> +
> +
> +static void aspeed_edac_disable_interrupts(void)
> +{
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_ENABLE, 0);
> +}
> +
> +
> +static void aspeed_edac_clear_interrupts(void)
> +{
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_CLEAR,
> +			   ASPEED_MCR_INTR_CTRL_CLEAR);
> +
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_CLEAR, 0);
> +}
> +
> +
> +static irqreturn_t aspeed_edac_isr(int irq, void *arg)
> +{
> +	u8  rec_cnt, un_rec_cnt;
> +	u32 rec_addr, un_rec_addr;
> +	struct mem_ctl_info *mci = arg;
> +	u32 reg50, reg5c, reg58;
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL, &reg50);
> +	dev_dbg(mci->pdev, "received edac interrupt w/ mmc register 50: 0x%x\n",
> +		reg50);
> +
> +	/* collect data about recoverable and unrecoverable errors */
> +	rec_cnt = (reg50 & ASPEED_MCR_INTR_CTRL_CNT_REC) >> 16;
> +	un_rec_cnt = (reg50 & ASPEED_MCR_INTR_CTRL_CNT_UNREC) >> 12;
> +
> +	dev_dbg(mci->pdev, "%d recoverable interrupts and %d unrecoverable interrupts\n",
> +		rec_cnt, un_rec_cnt);
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_ADDR_UNREC, &reg58);
> +	un_rec_addr = reg58 >> 4;

Now I better understand reg58. This is from aspeed docs:

- - - snip - - -
31:30 reserved (0)
29:4  Address of first un-recoverable ECC error
3:0   reserved (0)
- - - snip - - -

Bits 3:0 are indeed part of the address, but their values are not known and so
simply hardcoded to 0000. This is because there is one ECC byte for every 8
bytes and so the precision is 8-byte.

In other words, the whole register holds the address of the first
un-recoverable ECC error and so the shift must be removed:

 	un_rec_addr = reg58;


Sanity check: an address space of 29-4+1 bits would be quite small. The correct
address space is 30 bits.


> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_ADDR_REC, &reg5c);
> +	rec_addr = reg5c >> 4;

Same as above.


> +	/* clear interrupt flags and error counters: */
> +	aspeed_edac_clear_interrupts();
> +
> +	/* process recoverable and unrecoverable errors */
> +	if (rec_cnt > 0)
> +		aspeed_edac_count_rec(mci, rec_cnt, rec_addr);
> +
> +	if (un_rec_cnt > 0)
> +		aspeed_edac_count_un_rec(mci, un_rec_cnt, un_rec_addr);
> +
> +	if ((rec_cnt == 0) && (un_rec_cnt == 0))
> +		dev_dbg(mci->pdev, "received edac interrupt, but did not find any ecc counters\n");
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL, &reg50);
> +	dev_dbg(mci->pdev, "edac interrupt handled. mmc reg 50 is now: 0x%x\n",
> +		reg50);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +
> +static int aspeed_edac_config_irq(void *ctx,
> +				  struct platform_device *pdev)
> +{
> +	int irq;
> +	int rc;
> +
> +	/* register interrupt handler */
> +
> +	irq = platform_get_irq(pdev, 0);
> +	dev_dbg(&pdev->dev, "got irq %d\n", irq);
> +	if (!irq)
> +		return -ENODEV;
> +
> +	rc = devm_request_irq(&pdev->dev, irq, aspeed_edac_isr,
> +			      IRQF_TRIGGER_HIGH, DRV_NAME, ctx);
> +	if (rc) {
> +		dev_err(&pdev->dev, "unable to request irq %d\n", irq);
> +		return rc;
> +	}
> +
> +	/* enable interrupts */
> +	aspeed_edac_enable_interrupts();
> +
> +	return 0;
> +}
> +
> +
> +static int aspeed_edac_init_csrows(struct mem_ctl_info *mci)
> +{
> +	struct csrow_info *csrow = mci->csrows[0];
> +	struct dimm_info *dimm;
> +	struct device_node *np;
> +	u32 nr_pages, dram_type;
> +	struct resource r;
> +	u32 reg04;
> +	int rc;
> +
> +	/* retrieve info about physical memory from device tree */
> +	np = of_find_node_by_path("/memory");
> +
> +	if (!np) {
> +		dev_err(mci->pdev, "dt: missing /memory node\n");
> +		return -ENODEV;
> +	};
> +
> +	rc = of_address_to_resource(np, 0, &r);
> +
> +	of_node_put(np);
> +
> +	if (rc) {
> +		dev_err(mci->pdev, "dt: failed requesting resource for /memory node\n");
> +		return rc;
> +	};
> +
> +	dev_dbg(mci->pdev, "dt: /memory node resources: first page r.start=0x%x, resource_size=0x%x, PAGE_SHIFT macro=0x%x\n",
> +		r.start, resource_size(&r), PAGE_SHIFT);
> +
> +	csrow->first_page = r.start >> PAGE_SHIFT;
> +	nr_pages = resource_size(&r) >> PAGE_SHIFT;
> +	csrow->last_page = csrow->first_page + nr_pages - 1;
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
> +	dram_type = (reg04 & ASPEED_MCR_CONF_DRAM_TYPE) ? MEM_DDR4 : MEM_DDR3;
> +
> +	dimm = csrow->channels[0]->dimm;
> +	dimm->mtype = dram_type;
> +	dimm->edac_mode = EDAC_SECDED;
> +	dimm->nr_pages = nr_pages / csrow->nr_channels;
> +
> +	dev_dbg(mci->pdev, "initialized dimm with first_page=0x%lx and nr_pages=0x%x\n",
> +		csrow->first_page, nr_pages);
> +
> +	return 0;
> +}
> +
> +
> +static int aspeed_edac_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	void __iomem *regs;
> +	struct resource *res;
> +	struct mem_ctl_info *mci;
> +	struct edac_mc_layer layers[2];
> +	struct device_node *np;
> +	u32 reg04;
> +	int rc;
> +
> +	/* setup regmap */
> +	np = dev->of_node;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENOENT;
> +
> +	regs = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(regs))
> +		return PTR_ERR(regs);
> +
> +	aspeed_edac_regmap = devm_regmap_init(dev, NULL, (__force void *)regs,
> +					       &aspeed_edac_regmap_config);
> +	if (IS_ERR(aspeed_edac_regmap))
> +		return PTR_ERR(aspeed_edac_regmap);
> +
> +	/* bail out if ECC mode is not configured */
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
> +	if (!(reg04 & ASPEED_MCR_CONF_ECC)) {
> +		dev_err(&pdev->dev, "ECC mode is not configured in u-boot\n");
> +		return -EPERM;
> +	}
> +
> +	edac_op_state = EDAC_OPSTATE_INT;
> +
> +	/* allocate & init EDAC MC data structure */
> +	layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
> +	layers[0].size = 1;
> +	layers[0].is_virt_csrow = true;
> +	layers[1].type = EDAC_MC_LAYER_CHANNEL;
> +	layers[1].size = 1;
> +	layers[1].is_virt_csrow = false;
> +
> +	mci = edac_mc_alloc(0, ARRAY_SIZE(layers), layers, 0);
> +	if (mci == NULL)
> +		return -ENOMEM;
> +
> +	mci->pdev = &pdev->dev;
> +	mci->mtype_cap = MEM_FLAG_DDR3 | MEM_FLAG_DDR4;
> +	mci->edac_ctl_cap = EDAC_FLAG_SECDED;
> +	mci->edac_cap = EDAC_FLAG_SECDED;
> +	mci->scrub_cap = SCRUB_FLAG_HW_SRC;
> +	mci->scrub_mode = SCRUB_HW_SRC;
> +	mci->mod_name = DRV_NAME;
> +	mci->ctl_name = "MIC";
> +	mci->dev_name = dev_name(&pdev->dev);
> +
> +	rc = aspeed_edac_init_csrows(mci);
> +	if (rc) {
> +		dev_err(&pdev->dev, "failed to init csrows\n");
> +		goto probe_exit02;
> +	}
> +
> +	platform_set_drvdata(pdev, mci);
> +
> +	/* register with edac core */
> +	rc = edac_mc_add_mc(mci);
> +	if (rc) {
> +		dev_err(&pdev->dev, "failed to register with EDAC core\n");
> +		goto probe_exit02;
> +	}
> +
> +	/* register interrupt handler and enable interrupts */
> +	rc = aspeed_edac_config_irq(mci, pdev);
> +	if (rc) {
> +		dev_err(&pdev->dev, "failed setting up irq\n");
> +		goto probe_exit01;
> +	}
> +
> +	return 0;
> +
> +probe_exit01:
> +	edac_mc_del_mc(&pdev->dev);
> +probe_exit02:
> +	edac_mc_free(mci);
> +	return rc;
> +}
> +
> +
> +static int aspeed_edac_remove(struct platform_device *pdev)
> +{
> +	struct mem_ctl_info *mci;
> +
> +	/* disable interrupts */
> +	aspeed_edac_disable_interrupts();
> +
> +	/* free resources */
> +	mci = edac_mc_del_mc(&pdev->dev);
> +	if (mci)
> +		edac_mc_free(mci);
> +
> +	return 0;
> +}
> +
> +
> +static const struct of_device_id aspeed_edac_of_match[] = {
> +	{ .compatible = "aspeed,ast2500-sdram-edac" },
> +	{},
> +};
> +
> +
> +static struct platform_driver aspeed_edac_driver = {
> +	.driver		= {
> +		.name	= DRV_NAME,
> +		.of_match_table = aspeed_edac_of_match
> +	},
> +	.probe		= aspeed_edac_probe,
> +	.remove		= aspeed_edac_remove
> +};
> +
> +
> +static int __init aspeed_edac_init(void)
> +{
> +	return platform_driver_register(&aspeed_edac_driver);
> +}
> +
> +
> +static void __exit aspeed_edac_exit(void)
> +{
> +	platform_driver_unregister(&aspeed_edac_driver);
> +}
> +
> +
> +module_init(aspeed_edac_init);
> +module_exit(aspeed_edac_exit);
> +
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Stefan Schaeckeler <sschaeck@cisco.com>");
> +MODULE_DESCRIPTION("Aspeed AST2500 EDAC driver");
> +MODULE_VERSION("1.0");
> -- 
> 2.19.1
> 

 Stefan

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Re: [PATCH 1/2] EDAC: Add Aspeed AST2500 EDAC driver

[Boris Petkov]

On December 31, 2018 3:20:00 PM GMT+02:00, Stefan Schaeckeler <schaecsn@gmx.net> wrote:
>Let me start with reviewing my own driver. Perhaps someone could review
>it as well, please?

Someone will review it when the merge window and vacations are over.

-- 
Sent from a small device: formatting sux and brevity is inevitable. 

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Re: [PATCH 1/2] EDAC: Add Aspeed AST2500 EDAC driver

[Borislav Petkov]

On Sun, Dec 16, 2018 at 10:01:56PM -0800, Stefan Schaeckeler wrote:
> From: Stefan M Schaeckeler <sschaeck@cisco.com>
> 
> Add support for the Aspeed AST2500 SoC EDAC driver.
> 
> Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
> ---
>  MAINTAINERS                      |   6 +
>  arch/arm/boot/dts/aspeed-g5.dtsi |   7 +
>  drivers/edac/Kconfig             |   7 +
>  drivers/edac/Makefile            |   1 +
>  drivers/edac/aspeed_edac.c       | 457 +++++++++++++++++++++++++++++++
>  5 files changed, 478 insertions(+)
>  create mode 100644 drivers/edac/aspeed_edac.c

I couldn't see anything out of the ordinary - only nitpicks below.

> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3318f30903b2..1feb92b14029 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5315,6 +5315,12 @@ L:	linux-edac@vger.kernel.org
>  S:	Maintained
>  F:	drivers/edac/amd64_edac*
>  
> +EDAC-AST2500
> +M:	Stefan Schaeckeler <sschaeck@cisco.com>
> +S:	Supported
> +F:	drivers/edac/aspeed_edac.c
> +F:	Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> +
>  EDAC-CALXEDA
>  M:	Robert Richter <rric@kernel.org>
>  L:	linux-edac@vger.kernel.org
> diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
> index d107459fc0f8..b4e479ab5a2d 100644
> --- a/arch/arm/boot/dts/aspeed-g5.dtsi
> +++ b/arch/arm/boot/dts/aspeed-g5.dtsi
> @@ -47,6 +47,13 @@
>  		reg = <0x80000000 0>;
>  	};
>  
> +	edac: sdram@1e6e0000 {
> +		compatible = "aspeed,ast2500-sdram-edac";
> +		reg = <0x1e6e0000 0x174>;
> +		interrupts = <0>;
> +		status = "disabled";
> +	};
> +
>  	ahb {
>  		compatible = "simple-bus";
>  		#address-cells = <1>;
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 41c9ccdd20d6..67834430b0a1 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -475,4 +475,11 @@ config EDAC_QCOM
>  	  For debugging issues having to do with stability and overall system
>  	  health, you should probably say 'Y' here.
>  
> +config EDAC_ASPEED
> +	tristate "Aspeed AST 2500 SoC"
> +	depends on MACH_ASPEED_G5
> +	help
> +	  Support for error detection and correction on the
> +	  Aspeed AST 2500 SoC.
> +
>  endif # EDAC
> diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
> index 716096d08ea0..e1f23d4ff860 100644
> --- a/drivers/edac/Makefile
> +++ b/drivers/edac/Makefile
> @@ -78,3 +78,4 @@ obj-$(CONFIG_EDAC_SYNOPSYS)		+= synopsys_edac.o
>  obj-$(CONFIG_EDAC_XGENE)		+= xgene_edac.o
>  obj-$(CONFIG_EDAC_TI)			+= ti_edac.o
>  obj-$(CONFIG_EDAC_QCOM)			+= qcom_edac.o
> +obj-$(CONFIG_EDAC_ASPEED)		+= aspeed_edac.o
> diff --git a/drivers/edac/aspeed_edac.c b/drivers/edac/aspeed_edac.c
> new file mode 100644
> index 000000000000..d6ed119909eb
> --- /dev/null
> +++ b/drivers/edac/aspeed_edac.c
> @@ -0,0 +1,457 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2018 Cisco Systems
> + *
> + * 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.

You have the SPDX license identifier - no need for that text.

> + */
> +
> +#include <linux/edac.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/stop_machine.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/regmap.h>
> +#include <asm/page.h>
> +#include "edac_module.h"
> +
> +
> +#define DRV_NAME "aspeed-edac"
> +
> +
> +/* registers */

no need for that comment

> +#define ASPEED_MCR_PROT        0x00 /* protection key register */
> +#define ASPEED_MCR_CONF        0x04 /* configuration register */
> +#define ASPEED_MCR_INTR_CTRL   0x50 /* interrupt control/status register */
> +#define ASPEED_MCR_ADDR_UNREC  0x58 /* address of first un-recoverable error */
> +#define ASPEED_MCR_ADDR_REC    0x5c /* address of last recoverable error */
> +#define ASPEED_MCR_LAST        ASPEED_MCR_ADDR_REC
> +
> +
> +/* bits and masks */

ditto

> +#define ASPEED_MCR_PROT_PASSWD	            0xfc600309
> +#define ASPEED_MCR_CONF_DRAM_TYPE               BIT(4)
> +#define ASPEED_MCR_CONF_ECC                     BIT(7)
> +#define ASPEED_MCR_INTR_CTRL_CLEAR             BIT(31)
> +#define ASPEED_MCR_INTR_CTRL_CNT_REC   GENMASK(23, 16)
> +#define ASPEED_MCR_INTR_CTRL_CNT_UNREC GENMASK(15, 12)
> +#define ASPEED_MCR_INTR_CTRL_ENABLE  (BIT(0) | BIT(1))
> +
> +
> +
> +static int aspeed_edac_regmap_reg_write(void *context, unsigned int reg,
> +					unsigned int val)

All the static functions don't need the "aspeed_edac" prefix.

> +{
> +	void __iomem *regs = (void __iomem *)context;
> +
> +	/* enable write to MCR register set */
> +	writel(ASPEED_MCR_PROT_PASSWD, regs + ASPEED_MCR_PROT);
> +
> +	writel(val, regs + reg);
> +
> +	/* disable write to MCR register set */
> +	writel(~ASPEED_MCR_PROT_PASSWD, regs + ASPEED_MCR_PROT);
> +
> +	return 0;
> +}
> +
> +
> +static int aspeed_edac_regmap_reg_read(void *context, unsigned int reg,
> +				       unsigned int *val)
> +{
> +	void __iomem *regs = (void __iomem *)context;
> +
> +	*val = readl(regs + reg);
> +
> +	return 0;
> +}
> +
> +static bool aspeed_edac_regmap_is_volatile(struct device *dev,
> +					   unsigned int reg)
> +{
> +	switch (reg) {
> +	case ASPEED_MCR_PROT:
> +	case ASPEED_MCR_INTR_CTRL:
> +	case ASPEED_MCR_ADDR_UNREC:
> +	case ASPEED_MCR_ADDR_REC:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +
> +static const struct regmap_config aspeed_edac_regmap_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = ASPEED_MCR_LAST,
> +	.reg_write = aspeed_edac_regmap_reg_write,
> +	.reg_read = aspeed_edac_regmap_reg_read,
> +	.volatile_reg = aspeed_edac_regmap_is_volatile,
> +	.fast_io = true,
> +};
> +
> +
> +static struct regmap *aspeed_edac_regmap;

Put that definition at the top of the file, under the #defines.

> +
> +
> +static void aspeed_edac_count_rec(struct mem_ctl_info *mci,
> +				  u8 rec_cnt,
> +				  u32 rec_addr)
> +{
> +	struct csrow_info *csrow = mci->csrows[0];
> +	u32 page, offset, syndrome;
> +
> +	if (rec_cnt > 0) {

Save an indentation level:

	if (!rec_cnt)
		return;

> +		/* report first few errors (if there are) */
> +		/* note: no addresses are recorded */
> +		if (rec_cnt > 1) {
> +			page = 0; /* not available */
> +			offset = 0;  /* not available */
> +			syndrome = 0; /* not available */

Do a single comment, over the lines, not sideways. Ditto for the rest of
the driver - side comments make the code harder to read.

> +			edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci,
> +					     rec_cnt-1, page, offset,
> +					     syndrome, 0, 0, -1,
> +					     "address(es) not available", "");
> +		}
> +
> +		/* report last error */
> +		/* note: rec_addr is the last recoverable error addr */
> +		page = rec_addr >> PAGE_SHIFT;
> +		offset = rec_addr & ~PAGE_MASK;
> +		syndrome = 0; /* not available */
> +		edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci, 1,
> +				     csrow->first_page + page, offset, syndrome,
> +				     0, 0, -1, "", "");
> +	}
> +}
> +
> +
> +static void aspeed_edac_count_un_rec(struct mem_ctl_info *mci,
> +				     u8 un_rec_cnt,
> +				     u32 un_rec_addr)
> +{
> +	struct csrow_info *csrow = mci->csrows[0];
> +	u32 page, offset, syndrome;
> +
> +	if (un_rec_cnt > 0) {

As above: save an indentation level by flipping the check.

> +		/* report 1. error */
> +		/* note: un_rec_addr is the first unrecoverable error addr */
> +		page = un_rec_addr >> PAGE_SHIFT;
> +		offset = un_rec_addr & ~PAGE_MASK;
> +		syndrome = 0; /* not available */
> +		edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci, 1,
> +				     csrow->first_page + page, offset, syndrome,
> +				     0, 0, -1, "", "");
> +
> +		/* report further errors (if there are) */
> +		/* note: no addresses are recorded */
> +		if (un_rec_cnt > 1) {
> +			page = 0;  /* not available */
> +			offset = 0;  /* not available */
> +			syndrome = 0; /* not available */
> +			edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci,
> +					     un_rec_cnt-1, page, offset,
> +					     syndrome, 0, 0, -1,
> +					     "address(es) not available", "");
> +		}
> +	}
> +}
> +
> +
> +static void aspeed_edac_enable_interrupts(void)
> +{
> +
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_ENABLE,
> +			   ASPEED_MCR_INTR_CTRL_ENABLE);
> +}

A function which has a single statement and is called only once, looks
a bit useless to me. Just put the regmap_update_bits() call at the call
site with a comment (which you already have).

> +
> +
> +static void aspeed_edac_disable_interrupts(void)
> +{
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_ENABLE, 0);
> +}

Ditto.

> +
> +
> +static void aspeed_edac_clear_interrupts(void)
> +{
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_CLEAR,
> +			   ASPEED_MCR_INTR_CTRL_CLEAR);
> +
> +	regmap_update_bits(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL,
> +			   ASPEED_MCR_INTR_CTRL_CLEAR, 0);
> +}

Ditto.

> +
> +
> +static irqreturn_t aspeed_edac_isr(int irq, void *arg)
> +{
> +	u8  rec_cnt, un_rec_cnt;
> +	u32 rec_addr, un_rec_addr;
> +	struct mem_ctl_info *mci = arg;
> +	u32 reg50, reg5c, reg58;
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL, &reg50);
> +	dev_dbg(mci->pdev, "received edac interrupt w/ mmc register 50: 0x%x\n",
> +		reg50);
> +
> +	/* collect data about recoverable and unrecoverable errors */
> +	rec_cnt = (reg50 & ASPEED_MCR_INTR_CTRL_CNT_REC) >> 16;
> +	un_rec_cnt = (reg50 & ASPEED_MCR_INTR_CTRL_CNT_UNREC) >> 12;
> +
> +	dev_dbg(mci->pdev, "%d recoverable interrupts and %d unrecoverable interrupts\n",
> +		rec_cnt, un_rec_cnt);
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_ADDR_UNREC, &reg58);
> +	un_rec_addr = reg58 >> 4;
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_ADDR_REC, &reg5c);
> +	rec_addr = reg5c >> 4;
> +
> +	/* clear interrupt flags and error counters: */
> +	aspeed_edac_clear_interrupts();
> +
> +	/* process recoverable and unrecoverable errors */
> +	if (rec_cnt > 0)

You check rec_cnt here *and* in the function? One can never be sure huh? :-)

> +		aspeed_edac_count_rec(mci, rec_cnt, rec_addr);
> +
> +	if (un_rec_cnt > 0)
> +		aspeed_edac_count_un_rec(mci, un_rec_cnt, un_rec_addr);

Ditto. Just do the checks in the respective functions.

> +
> +	if ((rec_cnt == 0) && (un_rec_cnt == 0))

Do
	if (!rec_cnt && !un_rec_cnt)

> +		dev_dbg(mci->pdev, "received edac interrupt, but did not find any ecc counters\n");

s/ecc/ECC/g

> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_INTR_CTRL, &reg50);
> +	dev_dbg(mci->pdev, "edac interrupt handled. mmc reg 50 is now: 0x%x\n",
> +		reg50);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +
> +static int aspeed_edac_config_irq(void *ctx,
> +				  struct platform_device *pdev)

Let that line stick out.

> +{
> +	int irq;
> +	int rc;
> +
> +	/* register interrupt handler */
> +
> +	irq = platform_get_irq(pdev, 0);
> +	dev_dbg(&pdev->dev, "got irq %d\n", irq);
> +	if (!irq)
> +		return -ENODEV;
> +
> +	rc = devm_request_irq(&pdev->dev, irq, aspeed_edac_isr,
> +			      IRQF_TRIGGER_HIGH, DRV_NAME, ctx);
> +	if (rc) {
> +		dev_err(&pdev->dev, "unable to request irq %d\n", irq);
> +		return rc;
> +	}
> +
> +	/* enable interrupts */
> +	aspeed_edac_enable_interrupts();
> +
> +	return 0;
> +}
> +
> +
> +static int aspeed_edac_init_csrows(struct mem_ctl_info *mci)
> +{
> +	struct csrow_info *csrow = mci->csrows[0];
> +	struct dimm_info *dimm;
> +	struct device_node *np;
> +	u32 nr_pages, dram_type;
> +	struct resource r;
> +	u32 reg04;
> +	int rc;
> +
> +	/* retrieve info about physical memory from device tree */
> +	np = of_find_node_by_path("/memory");
> +

Superfluous new line.

> +	if (!np) {
> +		dev_err(mci->pdev, "dt: missing /memory node\n");
> +		return -ENODEV;
> +	};
> +
> +	rc = of_address_to_resource(np, 0, &r);
> +
> +	of_node_put(np);
> +
> +	if (rc) {
> +		dev_err(mci->pdev, "dt: failed requesting resource for /memory node\n");
> +		return rc;
> +	};
> +
> +	dev_dbg(mci->pdev, "dt: /memory node resources: first page r.start=0x%x, resource_size=0x%x, PAGE_SHIFT macro=0x%x\n",
> +		r.start, resource_size(&r), PAGE_SHIFT);
> +
> +	csrow->first_page = r.start >> PAGE_SHIFT;
> +	nr_pages = resource_size(&r) >> PAGE_SHIFT;
> +	csrow->last_page = csrow->first_page + nr_pages - 1;
> +
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
> +	dram_type = (reg04 & ASPEED_MCR_CONF_DRAM_TYPE) ? MEM_DDR4 : MEM_DDR3;
> +
> +	dimm = csrow->channels[0]->dimm;
> +	dimm->mtype = dram_type;
> +	dimm->edac_mode = EDAC_SECDED;
> +	dimm->nr_pages = nr_pages / csrow->nr_channels;
> +
> +	dev_dbg(mci->pdev, "initialized dimm with first_page=0x%lx and nr_pages=0x%x\n",
> +		csrow->first_page, nr_pages);
> +
> +	return 0;
> +}
> +
> +
> +static int aspeed_edac_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	void __iomem *regs;
> +	struct resource *res;
> +	struct mem_ctl_info *mci;
> +	struct edac_mc_layer layers[2];
> +	struct device_node *np;
> +	u32 reg04;
> +	int rc;

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;

Do that in all functions.

> +
> +	/* setup regmap */
> +	np = dev->of_node;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENOENT;
> +
> +	regs = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(regs))
> +		return PTR_ERR(regs);
> +
> +	aspeed_edac_regmap = devm_regmap_init(dev, NULL, (__force void *)regs,
> +					       &aspeed_edac_regmap_config);
> +	if (IS_ERR(aspeed_edac_regmap))
> +		return PTR_ERR(aspeed_edac_regmap);
> +
> +	/* bail out if ECC mode is not configured */
> +	regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
> +	if (!(reg04 & ASPEED_MCR_CONF_ECC)) {
> +		dev_err(&pdev->dev, "ECC mode is not configured in u-boot\n");
> +		return -EPERM;
> +	}
> +
> +	edac_op_state = EDAC_OPSTATE_INT;
> +
> +	/* allocate & init EDAC MC data structure */
> +	layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
> +	layers[0].size = 1;
> +	layers[0].is_virt_csrow = true;
> +	layers[1].type = EDAC_MC_LAYER_CHANNEL;
> +	layers[1].size = 1;
> +	layers[1].is_virt_csrow = false;
> +
> +	mci = edac_mc_alloc(0, ARRAY_SIZE(layers), layers, 0);
> +	if (mci == NULL)

	if (!mci)

> +		return -ENOMEM;
> +
> +	mci->pdev = &pdev->dev;
> +	mci->mtype_cap = MEM_FLAG_DDR3 | MEM_FLAG_DDR4;
> +	mci->edac_ctl_cap = EDAC_FLAG_SECDED;
> +	mci->edac_cap = EDAC_FLAG_SECDED;
> +	mci->scrub_cap = SCRUB_FLAG_HW_SRC;
> +	mci->scrub_mode = SCRUB_HW_SRC;
> +	mci->mod_name = DRV_NAME;
> +	mci->ctl_name = "MIC";
> +	mci->dev_name = dev_name(&pdev->dev);
> +
> +	rc = aspeed_edac_init_csrows(mci);
> +	if (rc) {
> +		dev_err(&pdev->dev, "failed to init csrows\n");
> +		goto probe_exit02;
> +	}
> +
> +	platform_set_drvdata(pdev, mci);
> +
> +	/* register with edac core */
> +	rc = edac_mc_add_mc(mci);
> +	if (rc) {
> +		dev_err(&pdev->dev, "failed to register with EDAC core\n");
> +		goto probe_exit02;
> +	}
> +
> +	/* register interrupt handler and enable interrupts */
> +	rc = aspeed_edac_config_irq(mci, pdev);
> +	if (rc) {
> +		dev_err(&pdev->dev, "failed setting up irq\n");
> +		goto probe_exit01;
> +	}
> +
> +	return 0;
> +
> +probe_exit01:
> +	edac_mc_del_mc(&pdev->dev);
> +probe_exit02:
> +	edac_mc_free(mci);
> +	return rc;
> +}

...

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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Re: [PATCH 1/2] EDAC: Add Aspeed AST2500 EDAC driver

[Stefan Schaeckeler]

Hello Boris,

Thank you for your feedback.

> From: Borislav Petkov <bp@alien8.de>
> 
> On Sun, Dec 16, 2018 at 10:01:56PM -0800, Stefan Schaeckeler wrote:
> > From: Stefan M Schaeckeler <sschaeck@cisco.com>
> > 
> > Add support for the Aspeed AST2500 SoC EDAC driver.
> > 
> > Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
> > ---
> >  MAINTAINERS                      |   6 +
> >  arch/arm/boot/dts/aspeed-g5.dtsi |   7 +
> >  drivers/edac/Kconfig             |   7 +
> >  drivers/edac/Makefile            |   1 +
> >  drivers/edac/aspeed_edac.c       | 457 +++++++++++++++++++++++++++++++
> >  5 files changed, 478 insertions(+)
> >  create mode 100644 drivers/edac/aspeed_edac.c
> 
> I couldn't see anything out of the ordinary - only nitpicks below.

[...]


> > diff --git a/drivers/edac/aspeed_edac.c b/drivers/edac/aspeed_edac.c
> > new file mode 100644
> > index 000000000000..d6ed119909eb
> > --- /dev/null
> > +++ b/drivers/edac/aspeed_edac.c
> > @@ -0,0 +1,457 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2018 Cisco Systems
> > + *
> > + * 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.
> 
> You have the SPDX license identifier - no need for that text.

That's interesting. I did a grep over all 16944 GPL licensed files with an SPDX
identifier.

785 of them have a license text while 16159 don't. I will remove mine.


> > +static int aspeed_edac_regmap_reg_write(void *context, unsigned int reg,
> > +					unsigned int val)
> 
> All the static functions don't need the "aspeed_edac" prefix.

When stripping off aspeed_edac_, some static function names will become quite
"bare-bone":

aspeed_edac_init(), aspeed_edac_exit(), aspeed_edac_probe(),
aspeed_edac_remove(), aspeed_edac_of_match(), aspeed_edac_isr(),
aspeed_edac_config_irq().


Does your suggestion also apply to static variables? E.g. aspeed_edac_regmap,
aspeed_edac_regmap_config, aspeed_edac_driver? Also, here some variable names
would become quite "bare-bone".

 Stefan

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Re: [PATCH 1/2] EDAC: Add Aspeed AST2500 EDAC driver

[Borislav Petkov]

On Tue, Jan 15, 2019 at 09:57:48AM -0800, Stefan Schaeckeler wrote:
> That's interesting. I did a grep over all 16944 GPL licensed files with an SPDX
> identifier.
> 
> 785 of them have a license text while 16159 don't.

Goes to show that we're still in the process of converting stuff to SPDX.

> When stripping off aspeed_edac_, some static function names will become quite
> "bare-bone":
> 
> aspeed_edac_init(), aspeed_edac_exit(), aspeed_edac_probe(),
> aspeed_edac_remove(), aspeed_edac_of_match(), aspeed_edac_isr(),
> aspeed_edac_config_irq().

So namespaced function names we normally use for globally visible
symbols and those are not but only driver-specific. So, for example,

aspeed_edac_config_irq()

is a mouthful, at least to me, and not needed. config_irq(), OTOH, is
clear at a very quick glance.

The others, aspeed_edac_init(), etc, you could call aspeed_init(),
aspeed_exit() or so.

But since you're going to be stare at that code, this was just a
suggestion. Your call. :)

> Does your suggestion also apply to static variables? E.g. aspeed_edac_regmap,
> aspeed_edac_regmap_config, aspeed_edac_driver? Also, here some variable names
> would become quite "bare-bone".

Same as above.

HTH.

-- 
Regards/Gruss,
    Boris.

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[PATCH 2/2] dt-bindings: edac: Aspeed AST2500

[Stefan Schaeckeler]

From: Stefan M Schaeckeler <sschaeck@cisco.com>

Add support for the Aspeed AST2500 SoC EDAC driver.

Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
---
 .../bindings/edac/aspeed-sdram-edac.txt       | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt

diff --git a/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt b/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
new file mode 100644
index 000000000000..57ba852883c7
--- /dev/null
+++ b/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
@@ -0,0 +1,34 @@
+Aspeed AST2500 SoC EDAC device driver
+
+The Aspeed AST2500 SoC supports DDR3 and DDR4 memory with and without ECC (error
+correction check).
+
+The memory controller supports SECDED (single bit error correction, double bit
+error detection) and single bit error auto scrubbing by reserving 8 bits for
+every 64 bit word (effectively reducing available memory to 8/9).
+
+First, ECC must be configured in u-boot. Then, this driver will expose error
+counters via the edac kernel framework.
+
+A note on memory organization in ECC mode: every 512 bytes are followed by 64
+bytes of ECC codes. The address remapping is done in hardware and is fully
+transparent to firmware and software. Because of this, ECC mode must be
+configured in u-boot as part of the memory initialization as one can not switch
+from one mode to another when executing in memory.
+
+
+
+Required properties:
+- compatible: should be "aspeed,ast2500-sdram-edac"
+- reg:        sdram controller register set should be <0x1e6e0000 0x174>
+- interrupts: should be AVIC interrupt #0
+
+
+Example:
+
+	edac: sdram@1e6e0000 {
+		compatible = "aspeed,ast2500-sdram-edac";
+		reg = <0x1e6e0000 0x174>;
+		interrupts = <0>;
+		status = "okay";
+	};
-- 
2.19.1


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Re: [PATCH 2/2] dt-bindings: edac: Aspeed AST2500

[Rob Herring]

On Sun, Dec 16, 2018 at 10:01:57PM -0800, Stefan Schaeckeler wrote:
> From: Stefan M Schaeckeler <sschaeck@cisco.com>
> 
> Add support for the Aspeed AST2500 SoC EDAC driver.
> 
> Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
> ---
>  .../bindings/edac/aspeed-sdram-edac.txt       | 34 +++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> 
> diff --git a/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt b/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> new file mode 100644
> index 000000000000..57ba852883c7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> @@ -0,0 +1,34 @@
> +Aspeed AST2500 SoC EDAC device driver

Bindings are for h/w, not drivers

> +
> +The Aspeed AST2500 SoC supports DDR3 and DDR4 memory with and without ECC (error
> +correction check).
> +
> +The memory controller supports SECDED (single bit error correction, double bit
> +error detection) and single bit error auto scrubbing by reserving 8 bits for
> +every 64 bit word (effectively reducing available memory to 8/9).
> +
> +First, ECC must be configured in u-boot. Then, this driver will expose error
> +counters via the edac kernel framework.

Please reword this to not be u-boot or kernel specific.

Maybe this node is enabled in the bootloader or the OS can just read the 
registers to see if ECC is enabled. The latter is more future proof if 
you need to access the DDR ctrl registers for other reasons.

> +
> +A note on memory organization in ECC mode: every 512 bytes are followed by 64
> +bytes of ECC codes. 

That sounds strange. Normally, the memory would be 72-bits wide to hold 
the ECC byte for each 64-bit chunk. It would be inefficient to access 
the ECC byte in a discontiguous location. In any case, none of this is 
really important for the binding.

> The address remapping is done in hardware and is fully
> +transparent to firmware and software. Because of this, ECC mode must be
> +configured in u-boot as part of the memory initialization as one can not switch
> +from one mode to another when executing in memory.
> +
> +
> +
> +Required properties:
> +- compatible: should be "aspeed,ast2500-sdram-edac"
> +- reg:        sdram controller register set should be <0x1e6e0000 0x174>
> +- interrupts: should be AVIC interrupt #0
> +
> +
> +Example:
> +
> +	edac: sdram@1e6e0000 {
> +		compatible = "aspeed,ast2500-sdram-edac";
> +		reg = <0x1e6e0000 0x174>;
> +		interrupts = <0>;
> +		status = "okay";

Don't show status in examples.

> +	};
> -- 
> 2.19.1
> 

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Re: [PATCH 2/2] dt-bindings: edac: Aspeed AST2500

[schaecsn]

Hello Rob,

> From: Rob Herring <robh@kernel.org>
> 
> On Sun, Dec 16, 2018 at 10:01:57PM -0800, Stefan Schaeckeler wrote:
> > From: Stefan M Schaeckeler <sschaeck@cisco.com>
> > 
> > Add support for the Aspeed AST2500 SoC EDAC driver.
> > 
> > Signed-off-by: Stefan M Schaeckeler <sschaeck@cisco.com>
> > ---
> >  .../bindings/edac/aspeed-sdram-edac.txt       | 34 +++++++++++++++++++
> >  1 file changed, 34 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt b/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> > new file mode 100644
> > index 000000000000..57ba852883c7
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/edac/aspeed-sdram-edac.txt
> > @@ -0,0 +1,34 @@
> > +Aspeed AST2500 SoC EDAC device driver
> 
> Bindings are for h/w, not drivers

Changed "device driver" to "node".

I will also change the commit message to perhaps "Add support for EDAC on the
Aspeed AST2500 SoC."


> > +The Aspeed AST2500 SoC supports DDR3 and DDR4 memory with and without ECC (error
> > +correction check).
> > +
> > +The memory controller supports SECDED (single bit error correction, double bit
> > +error detection) and single bit error auto scrubbing by reserving 8 bits for
> > +every 64 bit word (effectively reducing available memory to 8/9).
> > +
> > +First, ECC must be configured in u-boot. Then, this driver will expose error
> > +counters via the edac kernel framework.
> 
> Please reword this to not be u-boot or kernel specific.

The previous paragraph is now: Note, the bootloader must configure ECC mode in
the memory controller.

 
> Maybe this node is enabled in the bootloader or the OS can just read the 
> registers to see if ECC is enabled. The latter is more future proof if 
> you need to access the DDR ctrl registers for other reasons.

The driver's probe function has a sanity check. It consults the memory
controller for enabled ECC mode:
 
        /* bail out if ECC mode is not configured */
        regmap_read(aspeed_edac_regmap, ASPEED_MCR_CONF, &reg04);
        if (!(reg04 & ASPEED_MCR_CONF_ECC)) {
                dev_err(&pdev->dev, "ECC mode is not configured in u-boot\n");
                return -EPERM;
        }


> > +A note on memory organization in ECC mode: every 512 bytes are followed by 64
> > +bytes of ECC codes. 
> 
> That sounds strange. Normally, the memory would be 72-bits wide to hold 
> the ECC byte for each 64-bit chunk. It would be inefficient to access 
> the ECC byte in a discontiguous location.

When a word is loaded from memory, the corresponding ECC word needs to be
loaded as well (both words can and will be cached). Performance relies on
temporal and spatial locality. That can fire back, of course.


> In any case, none of this is really important for the binding.

I will move above and below paragraph into Kconfig.


> > The address remapping is done in hardware and is fully
> > +transparent to firmware and software. Because of this, ECC mode must be
> > +configured in u-boot as part of the memory initialization as one can not switch
> > +from one mode to another when executing in memory.
> > +
> > +
> > +
> > +Required properties:
> > +- compatible: should be "aspeed,ast2500-sdram-edac"
> > +- reg:        sdram controller register set should be <0x1e6e0000 0x174>
> > +- interrupts: should be AVIC interrupt #0
> > +
> > +
> > +Example:
> > +
> > +	edac: sdram@1e6e0000 {
> > +		compatible = "aspeed,ast2500-sdram-edac";
> > +		reg = <0x1e6e0000 0x174>;
> > +		interrupts = <0>;
> > +		status = "okay";
> 
> Don't show status in examples.

Removed.

> 
> > +	};
> > -- 
> > 2.19.1


To wrap it up, for the next patchset, I will generate a diff for below text

- - - snip - - -
Aspeed AST2500 SoC EDAC node

The Aspeed AST2500 SoC supports DDR3 and DDR4 memory with and without ECC (error
correction check).

The memory controller supports SECDED (single bit error correction, double bit
error detection) and single bit error auto scrubbing by reserving 8 bits for
every 64 bit word (effectively reducing available memory to 8/9).

Note, the bootloader must configure ECC mode in the memory controller.


Required properties:
- compatible: should be "aspeed,ast2500-sdram-edac"
- reg:        sdram controller register set should be <0x1e6e0000 0x174>
- interrupts: should be AVIC interrupt #0


Example:

        edac: sdram@1e6e0000 {
                compatible = "aspeed,ast2500-sdram-edac";
                reg = <0x1e6e0000 0x174>;
                interrupts = <0>;
        };
- - - snip - - -

 Stefan


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