Message-ID: <20191011092306.41a4c9a9@why>
Date:   Fri, 11 Oct 2019 09:23:06 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Talel Shenhar <talel@...zon.com>
Cc:     <robh+dt@...nel.org>, <mark.rutland@....com>, <arnd@...db.de>,
        <bp@...en8.de>, <mchehab@...nel.org>, <james.morse@....com>,
        <davem@...emloft.net>, <gregkh@...uxfoundation.org>,
        <paulmck@...ux.ibm.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-edac@...r.kernel.org>,
        <dwmw@...zon.co.uk>, <benh@...nel.crashing.org>,
        <hhhawa@...zon.com>, <ronenk@...zon.com>, <jonnyc@...zon.com>,
        <hanochu@...zon.com>, <amirkl@...zon.com>, <barakw@...zon.com>
Subject: Re: [PATCH v4 2/2] EDAC: al-mc-edac: Introduce Amazon's Annapurna
 Labs Memory Controller EDAC

On Thu, 10 Oct 2019 14:54:14 +0300
Talel Shenhar <talel@...zon.com> wrote:

Hi Talel,

> The Amazon's Annapurna Labs Memory Controller EDAC supports ECC capability
> for error detection and correction (Single bit error correction, Double
> detection). This driver introduces EDAC driver for that capability.
> 
> Signed-off-by: Talel Shenhar <talel@...zon.com>
> ---
>  MAINTAINERS               |   7 +
>  drivers/edac/Kconfig      |   7 +
>  drivers/edac/Makefile     |   1 +
>  drivers/edac/al_mc_edac.c | 358 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 373 insertions(+)
>  create mode 100644 drivers/edac/al_mc_edac.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 55199ef..d431e8f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -757,6 +757,13 @@ F:	drivers/tty/serial/altera_jtaguart.c
>  F:	include/linux/altera_uart.h
>  F:	include/linux/altera_jtaguart.h
>  
> +AMAZON ANNAPURNA LABS MEMORY CONTROLLER EDAC
> +M:	Talel Shenhar <talel@...zon.com>
> +M:	Talel Shenhar <talelshenhar@...il.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/edac/amazon,al-mc-edac.yaml
> +F:	drivers/edac/al_mc_edac.c
> +
>  AMAZON ANNAPURNA LABS THERMAL MMIO DRIVER
>  M:	Talel Shenhar <talel@...zon.com>
>  S:	Maintained
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 417dad6..8c7fb73 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -100,6 +100,13 @@ config EDAC_AMD64_ERROR_INJECTION
>  	  In addition, there are two control files, inject_read and inject_write,
>  	  which trigger the DRAM ECC Read and Write respectively.
>  
> +config EDAC_AL_MC
> +	tristate "Amazon's Annapurna Lab EDAC Memory Controller"
> +	depends on (ARCH_ALPINE || COMPILE_TEST)
> +	help
> +	  Support for error detection and correction for Amazon's Annapurna
> +	  Labs Alpine chips which allows 1 bit correction and 2 bits detection.
> +
>  config EDAC_AMD76X
>  	tristate "AMD 76x (760, 762, 768)"
>  	depends on PCI && X86_32
> diff --git a/drivers/edac/Makefile b/drivers/edac/Makefile
> index d77200c..5288329 100644
> --- a/drivers/edac/Makefile
> +++ b/drivers/edac/Makefile
> @@ -22,6 +22,7 @@ obj-$(CONFIG_EDAC_GHES)			+= ghes_edac.o
>  edac_mce_amd-y				:= mce_amd.o
>  obj-$(CONFIG_EDAC_DECODE_MCE)		+= edac_mce_amd.o
>  
> +obj-$(CONFIG_EDAC_AL_MC)		+= al_mc_edac.o
>  obj-$(CONFIG_EDAC_AMD76X)		+= amd76x_edac.o
>  obj-$(CONFIG_EDAC_CPC925)		+= cpc925_edac.o
>  obj-$(CONFIG_EDAC_I5000)		+= i5000_edac.o
> diff --git a/drivers/edac/al_mc_edac.c b/drivers/edac/al_mc_edac.c
> new file mode 100644
> index 00000000..f1288c4
> --- /dev/null
> +++ b/drivers/edac/al_mc_edac.c
> @@ -0,0 +1,358 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/bitops.h>
> +#include <linux/edac.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include "edac_module.h"
> +
> +/* Registers Offset */
> +#define AL_MC_MSTR		0x00
> +#define AL_MC_ECC_CFG		0x70
> +#define AL_MC_ECC_CLEAR		0x7c
> +#define AL_MC_ECC_ERR_COUNT	0x80
> +#define AL_MC_ECC_CE_ADDR0	0x84
> +#define AL_MC_ECC_CE_ADDR1	0x88
> +#define AL_MC_ECC_UE_ADDR0	0xa4
> +#define AL_MC_ECC_UE_ADDR1	0xa8
> +#define AL_MC_ECC_CE_SYND0	0x8c
> +#define AL_MC_ECC_CE_SYND1	0x90
> +#define AL_MC_ECC_CE_SYND2	0x94
> +#define AL_MC_ECC_UE_SYND0	0xac
> +#define AL_MC_ECC_UE_SYND1	0xb0
> +#define AL_MC_ECC_UE_SYND2	0xb4
> +
> +/* Registers Fields */
> +#define AL_MC_MSTR_DEV_CFG		GENMASK(31, 30)
> +#define AL_MC_MSTR_RANKS		GENMASK(27, 24)
> +#define AL_MC_MSTR_DATA_BUS_WIDTH	GENMASK(13, 12)
> +#define AL_MC_MSTR_DDR4			BIT(4)
> +#define AL_MC_MSTR_DDR3			BIT(0)
> +
> +#define AL_MC_ECC_CFG_SCRUB_DISABLED	BIT(4)
> +#define AL_MC_ECC_CFG_ECC_MODE		GENMASK(2, 0)
> +
> +#define AL_MC_ECC_CLEAR_UE_COUNT	BIT(3)
> +#define AL_MC_ECC_CLEAR_CE_COUNT	BIT(2)
> +#define AL_MC_ECC_CLEAR_UE_ERR		BIT(1)
> +#define AL_MC_ECC_CLEAR_CE_ERR		BIT(0)
> +
> +#define AL_MC_ECC_ERR_COUNT_UE		GENMASK(31, 16)
> +#define AL_MC_ECC_ERR_COUNT_CE		GENMASK(15, 0)
> +
> +#define AL_MC_ECC_CE_ADDR0_RANK		GENMASK(25, 24)
> +#define AL_MC_ECC_CE_ADDR0_ROW		GENMASK(17, 0)
> +
> +#define AL_MC_ECC_CE_ADDR1_BG		GENMASK(25, 24)
> +#define AL_MC_ECC_CE_ADDR1_BANK		GENMASK(18, 16)
> +#define AL_MC_ECC_CE_ADDR1_COLUMN	GENMASK(11, 0)
> +
> +#define AL_MC_ECC_UE_ADDR0_RANK		GENMASK(25, 24)
> +#define AL_MC_ECC_UE_ADDR0_ROW		GENMASK(17, 0)
> +
> +#define AL_MC_ECC_UE_ADDR1_BG		GENMASK(25, 24)
> +#define AL_MC_ECC_UE_ADDR1_BANK		GENMASK(18, 16)
> +#define AL_MC_ECC_UE_ADDR1_COLUMN	GENMASK(11, 0)
> +
> +/* Registers Values */
> +#define AL_MC_MSTR_DEV_CFG_X4	0
> +#define AL_MC_MSTR_DEV_CFG_X8	1
> +#define AL_MC_MSTR_DEV_CFG_X16	2
> +#define AL_MC_MSTR_DEV_CFG_X32	3
> +#define AL_MC_MSTR_RANKS_MAX 4
> +#define AL_MC_MSTR_DATA_BUS_WIDTH_X64	0
> +
> +#define DRV_NAME "al_mc_edac"
> +#define AL_MC_EDAC_MSG_MAX 256
> +#define AL_MC_EDAC_MSG(message, buffer_size, type,			\
> +		       rank, row, bg, bank, column, syn0, syn1, syn2)	\
> +	snprintf(message, buffer_size,					\
> +		 "%s rank=0x%x row=0x%x bg=0x%x bank=0x%x col=0x%x "	\
> +		 "syn0: 0x%x syn1: 0x%x syn2: 0x%x",			\
> +		 type == HW_EVENT_ERR_UNCORRECTED ? "UE" : "CE",	\
> +		 rank, row, bg, bank, column, syn0, syn1, syn2)
> +
> +struct al_mc_edac {
> +	void __iomem *mmio_base;
> +	spinlock_t lock;
> +	int irq_ce;
> +	int irq_ue;
> +};
> +
> +static int al_mc_edac_handle_ce(struct mem_ctl_info *mci)
> +{
> +	struct al_mc_edac *al_mc = mci->pvt_info;
> +	u32 eccerrcnt, ecccaddr0, ecccaddr1, ecccsyn0, ecccsyn1, ecccsyn2, row;
> +	u16 ce_count, column;
> +	u8 rank, bg, bank;
> +	char msg[AL_MC_EDAC_MSG_MAX];
> +	unsigned long flags;
> +
> +	eccerrcnt = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_ERR_COUNT);
> +	ce_count = FIELD_GET(AL_MC_ECC_ERR_COUNT_CE, eccerrcnt);
> +	if (!ce_count)
> +		return 0;
> +
> +	ecccaddr0 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_CE_ADDR0);
> +	ecccaddr1 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_CE_ADDR1);
> +	ecccsyn0 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_SYND0);
> +	ecccsyn1 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_SYND1);
> +	ecccsyn2 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_SYND2);
> +
> +	writel(AL_MC_ECC_CLEAR_CE_COUNT | AL_MC_ECC_CLEAR_CE_ERR,
> +	       al_mc->mmio_base + AL_MC_ECC_CLEAR);

Why the non-relaxed write? All the accesses are ordered by virtue of
interacting with the same device, and I can't see anything that
requires ordering with normal memory accesses prior to this write.

This pattern appears throughout the driver, and I think they can all be
relaxed. If not, please document the reason why they can't.

> +
> +	dev_dbg(mci->pdev, "eccuaddr0=0x%08x eccuaddr1=0x%08x\n",
> +		ecccaddr0, ecccaddr1);
> +
> +	rank = FIELD_GET(AL_MC_ECC_CE_ADDR0_RANK, ecccaddr0);
> +	row = FIELD_GET(AL_MC_ECC_CE_ADDR0_ROW, ecccaddr0);
> +
> +	bg = FIELD_GET(AL_MC_ECC_CE_ADDR1_BG, ecccaddr1);
> +	bank = FIELD_GET(AL_MC_ECC_CE_ADDR1_BANK, ecccaddr1);
> +	column = FIELD_GET(AL_MC_ECC_CE_ADDR1_COLUMN, ecccaddr1);
> +
> +	AL_MC_EDAC_MSG(msg, sizeof(msg), HW_EVENT_ERR_CORRECTED,
> +		       rank, row, bg, bank, column,
> +		       ecccsyn0, ecccsyn1, ecccsyn2);
> +
> +	spin_lock_irqsave(&al_mc->lock, flags);
> +	edac_mc_handle_error(HW_EVENT_ERR_CORRECTED, mci,
> +			     ce_count, 0, 0, 0, 0, 0, -1, mci->ctl_name, msg);
> +	spin_unlock_irqrestore(&al_mc->lock, flags);
> +
> +	return ce_count;
> +}
> +
> +static int al_mc_edac_handle_ue(struct mem_ctl_info *mci)
> +{
> +	struct al_mc_edac *al_mc = mci->pvt_info;
> +	u32 eccerrcnt, eccuaddr0, eccuaddr1, eccusyn0, eccusyn1, eccusyn2, row;
> +	u16 ue_count, column;
> +	u8 rank, bg, bank;
> +	char msg[AL_MC_EDAC_MSG_MAX];
> +	unsigned long flags;
> +
> +	eccerrcnt = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_ERR_COUNT);
> +	ue_count = FIELD_GET(AL_MC_ECC_ERR_COUNT_UE, eccerrcnt);
> +	if (!ue_count)
> +		return 0;
> +
> +	eccuaddr0 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_ADDR0);
> +	eccuaddr1 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_ADDR1);
> +	eccusyn0 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_SYND0);
> +	eccusyn1 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_SYND1);
> +	eccusyn2 = readl_relaxed(al_mc->mmio_base + AL_MC_ECC_UE_SYND2);
> +
> +	writel(AL_MC_ECC_CLEAR_UE_COUNT | AL_MC_ECC_CLEAR_UE_ERR,
> +	       al_mc->mmio_base + AL_MC_ECC_CLEAR);
> +
> +	dev_dbg(mci->pdev, "eccuaddr0=0x%08x eccuaddr1=0x%08x\n",
> +		eccuaddr0, eccuaddr1);
> +
> +	rank = FIELD_GET(AL_MC_ECC_UE_ADDR0_RANK, eccuaddr0);
> +	row = FIELD_GET(AL_MC_ECC_UE_ADDR0_ROW, eccuaddr0);
> +
> +	bg = FIELD_GET(AL_MC_ECC_UE_ADDR1_BG, eccuaddr1);
> +	bank = FIELD_GET(AL_MC_ECC_UE_ADDR1_BANK, eccuaddr1);
> +	column = FIELD_GET(AL_MC_ECC_UE_ADDR1_COLUMN, eccuaddr1);
> +
> +	AL_MC_EDAC_MSG(msg, sizeof(msg), HW_EVENT_ERR_UNCORRECTED,
> +		       rank, row, bg, bank, column,
> +		       eccusyn0, eccusyn1, eccusyn2);
> +
> +	spin_lock_irqsave(&al_mc->lock, flags);
> +	edac_mc_handle_error(HW_EVENT_ERR_UNCORRECTED, mci,
> +			     ue_count, 0, 0, 0, 0, 0, -1, mci->ctl_name, msg);
> +	spin_unlock_irqrestore(&al_mc->lock, flags);
> +
> +	return ue_count;
> +}
> +
> +static void al_mc_edac_check(struct mem_ctl_info *mci)
> +{
> +	struct al_mc_edac *al_mc = mci->pvt_info;
> +
> +	if (al_mc->irq_ue <= 0)
> +		al_mc_edac_handle_ue(mci);
> +
> +	if (al_mc->irq_ce <= 0)
> +		al_mc_edac_handle_ce(mci);
> +}
> +
> +static irqreturn_t al_mc_edac_irq_handler_ue(int irq, void *info)
> +{
> +	struct platform_device *pdev = info;
> +	struct mem_ctl_info *mci = platform_get_drvdata(pdev);
> +
> +	if (al_mc_edac_handle_ue(mci))
> +		return IRQ_HANDLED;
> +	return IRQ_NONE;
> +}
> +
> +static irqreturn_t al_mc_edac_irq_handler_ce(int irq, void *info)
> +{
> +	struct platform_device *pdev = info;
> +	struct mem_ctl_info *mci = platform_get_drvdata(pdev);
> +
> +	if (al_mc_edac_handle_ce(mci))
> +		return IRQ_HANDLED;
> +	return IRQ_NONE;
> +}
> +
> +static enum scrub_type al_mc_edac_get_scrub_mode(void __iomem *mmio_base)
> +{
> +	u32 ecccfg0;
> +
> +	ecccfg0 = readl(mmio_base + AL_MC_ECC_CFG);
> +
> +	if (FIELD_GET(AL_MC_ECC_CFG_SCRUB_DISABLED, ecccfg0))
> +		return SCRUB_NONE;
> +	else
> +		return SCRUB_HW_SRC;
> +}
> +
> +static int al_mc_edac_probe(struct platform_device *pdev)
> +{
> +	void __iomem *mmio_base;
> +	struct edac_mc_layer layers[1];
> +	struct mem_ctl_info *mci;
> +	struct al_mc_edac *al_mc;
> +	int ret;
> +
> +	mmio_base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(mmio_base)) {
> +		dev_err(&pdev->dev, "failed to ioremap memory (%ld)\n",
> +			PTR_ERR(mmio_base));
> +		return PTR_ERR(mmio_base);
> +	}
> +
> +	layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
> +	layers[0].size = 1;
> +	layers[0].is_virt_csrow = false;
> +	mci = edac_mc_alloc(0, ARRAY_SIZE(layers), layers,
> +			    sizeof(struct al_mc_edac));
> +	if (!mci)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, mci);
> +	al_mc = mci->pvt_info;
> +
> +	al_mc->mmio_base = mmio_base;
> +
> +	al_mc->irq_ue = of_irq_get_byname(pdev->dev.of_node, "ue");
> +	if (al_mc->irq_ue <= 0)
> +		dev_dbg(&pdev->dev,
> +			"no irq defined for ue - falling back to polling\n");
> +
> +	al_mc->irq_ce = of_irq_get_byname(pdev->dev.of_node, "ce");
> +	if (al_mc->irq_ce <= 0)
> +		dev_dbg(&pdev->dev,
> +			"no irq defined for ce - falling back to polling\n");
> +
> +	if (al_mc->irq_ue <= 0 || al_mc->irq_ce <= 0)
> +		edac_op_state = EDAC_OPSTATE_POLL;
> +	else
> +		edac_op_state = EDAC_OPSTATE_INT;
> +
> +	spin_lock_init(&al_mc->lock);
> +
> +	mci->edac_check = al_mc_edac_check;
> +	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->mod_name = DRV_NAME;
> +	mci->ctl_name = "al_mc";
> +	mci->pdev = &pdev->dev;
> +	mci->scrub_mode = al_mc_edac_get_scrub_mode(mmio_base);
> +
> +	ret = edac_mc_add_mc(mci);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev,
> +			"fail to add memory controller device (%d)\n",
> +			ret);
> +		goto err_add_mc;
> +	}
> +
> +	if (al_mc->irq_ue > 0) {
> +		ret = devm_request_irq(&pdev->dev,
> +				       al_mc->irq_ue,
> +				       al_mc_edac_irq_handler_ue,
> +				       IRQF_SHARED,
> +				       pdev->name,
> +				       pdev);
> +		if (ret != 0) {
> +			dev_err(&pdev->dev,
> +				"failed to request ue irq %d (%d)\n",
> +				al_mc->irq_ue, ret);
> +			goto err_request_irq;
> +		}
> +	}
> +
> +	if (al_mc->irq_ce > 0) {
> +		ret = devm_request_irq(&pdev->dev,
> +				       al_mc->irq_ce,
> +				       al_mc_edac_irq_handler_ce,
> +				       IRQF_SHARED,
> +				       pdev->name,
> +				       pdev);
> +		if (ret != 0) {
> +			dev_err(&pdev->dev,
> +				"failed to request ce irq %d (%d)\n",
> +				al_mc->irq_ce, ret);
> +			goto err_request_irq;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_request_irq:
> +	edac_mc_del_mc(&pdev->dev);
> +err_add_mc:
> +	edac_mc_free(mci);
> +
> +	return ret;
> +}
> +
> +static int al_mc_edac_remove(struct platform_device *pdev)
> +{
> +	struct mem_ctl_info *mci = platform_get_drvdata(pdev);
> +	struct al_mc_edac *al_mc = mci->pvt_info;
> +
> +	if (al_mc->irq_ue > 0)
> +		devm_free_irq(&pdev->dev, al_mc->irq_ue, pdev);
> +
> +	if (al_mc->irq_ce > 0)
> +		devm_free_irq(&pdev->dev, al_mc->irq_ce, pdev);
> +
> +	edac_mc_del_mc(&pdev->dev);
> +	edac_mc_free(mci);

nit: I always find the mix of devm_* stuff with non-devm pretty
awkward, as you end-up tracking things anyway (here, and in the error
path of the probe function).

I found the use of devm_add_action() to be pretty good at decluttering
probe and remove entry points, as you just register destructors each
time you allocate objects, and can forget any form of subsequent
tracking.

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id al_mc_edac_of_match[] = {
> +	{ .compatible = "amazon,al-mc-edac", },
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(of, al_mc_edac_of_match);
> +
> +static struct platform_driver al_mc_edac_driver = {
> +	.probe = al_mc_edac_probe,
> +	.remove = al_mc_edac_remove,
> +	.driver = {
> +		.name = DRV_NAME,
> +		.of_match_table = al_mc_edac_of_match,
> +	},
> +};
> +
> +module_platform_driver(al_mc_edac_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Talel Shenhar");
> +MODULE_DESCRIPTION("Amazon's Annapurna Lab's Memory Controller EDAC Driver");

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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