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Date:   Thu, 08 Sep 2022 08:39:47 +0100
Message-ID: <87fsh2qpq4.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Frank Li <Frank.Li@nxp.com>
Cc:     tglx@linutronix.de, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, shawnguo@kernel.org,
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        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
        peng.fan@nxp.com, aisheng.dong@nxp.com, jdmason@kudzu.us,
        kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
        kishon@ti.com, lorenzo.pieralisi@arm.com, ntb@lists.linux.dev,
        lznuaa@gmail.com, imx@lists.linux.dev,
        manivannan.sadhasivam@linaro.org
Subject: Re: [PATCH v9 2/4] irqchip: Add IMX MU MSI controller driver
In-Reply-To: <20220907034856.3101570-3-Frank.Li@nxp.com>
References: <20220907034856.3101570-1-Frank.Li@nxp.com>
        <20220907034856.3101570-3-Frank.Li@nxp.com>
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On Wed, 07 Sep 2022 04:48:54 +0100,
Frank Li <Frank.Li@nxp.com> wrote:
> 
> The MU block found in a number of Freescale/NXP SoCs supports generating
> IRQs by writing data to a register
> 
> This enables the MU block to be used as a MSI controller, by leveraging
> the platform-MSI API

Missing full stop after each sentence.

> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>  drivers/irqchip/Kconfig          |   9 +
>  drivers/irqchip/Makefile         |   1 +
>  drivers/irqchip/irq-imx-mu-msi.c | 451 +++++++++++++++++++++++++++++++
>  3 files changed, 461 insertions(+)
>  create mode 100644 drivers/irqchip/irq-imx-mu-msi.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 5e4e50122777d..e04c6521dce55 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -470,6 +470,15 @@ config IMX_INTMUX
>  	help
>  	  Support for the i.MX INTMUX interrupt multiplexer.
>  
> +config IMX_MU_MSI
> +	bool "i.MX MU work as MSI controller"

Why bool? Doesn't it also work as a module?

> +	default y if ARCH_MXC

Why would this be selected by default?

> +	select IRQ_DOMAIN
> +	select IRQ_DOMAIN_HIERARCHY
> +	select GENERIC_MSI_IRQ_DOMAIN
> +	help
> +	  MU work as MSI controller to do general doorbell

I'm not sure this is that generic. It really is limited to CPU-to-CPU
interrupts.

> +
>  config LS1X_IRQ
>  	bool "Loongson-1 Interrupt Controller"
>  	depends on MACH_LOONGSON32
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 5d8e21d3dc6d8..870423746c783 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -98,6 +98,7 @@ obj-$(CONFIG_RISCV_INTC)		+= irq-riscv-intc.o
>  obj-$(CONFIG_SIFIVE_PLIC)		+= irq-sifive-plic.o
>  obj-$(CONFIG_IMX_IRQSTEER)		+= irq-imx-irqsteer.o
>  obj-$(CONFIG_IMX_INTMUX)		+= irq-imx-intmux.o
> +obj-$(CONFIG_IMX_MU_MSI)		+= irq-imx-mu-msi.o
>  obj-$(CONFIG_MADERA_IRQ)		+= irq-madera.o
>  obj-$(CONFIG_LS1X_IRQ)			+= irq-ls1x.o
>  obj-$(CONFIG_TI_SCI_INTR_IRQCHIP)	+= irq-ti-sci-intr.o
> diff --git a/drivers/irqchip/irq-imx-mu-msi.c b/drivers/irqchip/irq-imx-mu-msi.c
> new file mode 100644
> index 0000000000000..82b55f6d87266
> --- /dev/null
> +++ b/drivers/irqchip/irq-imx-mu-msi.c
> @@ -0,0 +1,451 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Freescale MU worked as MSI controller

s/worked/used/

> + *
> + * Copyright (c) 2018 Pengutronix, Oleksij Rempel <o.rempel@pengutronix.de>
> + * Copyright 2022 NXP
> + *	Frank Li <Frank.Li@nxp.com>
> + *	Peng Fan <peng.fan@nxp.com>
> + *
> + * Based on drivers/mailbox/imx-mailbox.c
> + */
> +#include <linux/clk.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqdomain.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_pci.h>
> +#include <linux/of_platform.h>
> +#include <linux/spinlock.h>
> +#include <linux/dma-iommu.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/pm_domain.h>

Keep this list in alphabetical order.

> +
> +
> +#define IMX_MU_CHANS            4
> +
> +enum imx_mu_xcr {
> +	IMX_MU_GIER,
> +	IMX_MU_GCR,
> +	IMX_MU_TCR,
> +	IMX_MU_RCR,
> +	IMX_MU_xCR_MAX,

What is this last enum used for?

> +};
> +
> +enum imx_mu_xsr {
> +	IMX_MU_SR,
> +	IMX_MU_GSR,
> +	IMX_MU_TSR,
> +	IMX_MU_RSR,
> +};
> +
> +enum imx_mu_type {
> +	IMX_MU_V1 = BIT(0),

This is never used. Why?

> +	IMX_MU_V2 = BIT(1),
> +	IMX_MU_V2_S4 = BIT(15),

Same thing.

> +};
> +
> +/* Receive Interrupt Enable */
> +#define IMX_MU_xCR_RIEn(data, x) ((data->cfg->type) & IMX_MU_V2 ? BIT(x) : BIT(24 + (3 - (x))))
> +#define IMX_MU_xSR_RFn(data, x) ((data->cfg->type) & IMX_MU_V2 ? BIT(x) : BIT(24 + (3 - (x))))
> +
> +struct imx_mu_dcfg {
> +	enum imx_mu_type type;
> +	u32     xTR;            /* Transmit Register0 */
> +	u32     xRR;            /* Receive Register0 */
> +	u32     xSR[4];         /* Status Registers */
> +	u32     xCR[4];         /* Control Registers */
> +};
> +
> +struct imx_mu_msi {
> +	spinlock_t			lock;
> +	raw_spinlock_t			reglock;

Why two locks? Isn't one enough to protect both MSI allocation (which
happens once in a blue moon) and register access?

Also, where are these locks initialised?

> +	struct irq_domain		*msi_domain;
> +	void __iomem			*regs;
> +	phys_addr_t			msiir_addr;
> +	const struct imx_mu_dcfg	*cfg;
> +	unsigned long			used;
> +	struct clk			*clk;
> +};
> +
> +static void imx_mu_write(struct imx_mu_msi *msi_data, u32 val, u32 offs)
> +{
> +	iowrite32(val, msi_data->regs + offs);
> +}
> +
> +static u32 imx_mu_read(struct imx_mu_msi *msi_data, u32 offs)
> +{
> +	return ioread32(msi_data->regs + offs);
> +}
> +
> +static u32 imx_mu_xcr_rmw(struct imx_mu_msi *msi_data, enum imx_mu_xcr type, u32 set, u32 clr)
> +{
> +	unsigned long flags;
> +	u32 val;
> +
> +	raw_spin_lock_irqsave(&msi_data->reglock, flags);
> +	val = imx_mu_read(msi_data, msi_data->cfg->xCR[type]);
> +	val &= ~clr;
> +	val |= set;
> +	imx_mu_write(msi_data, val, msi_data->cfg->xCR[type]);
> +	raw_spin_unlock_irqrestore(&msi_data->reglock, flags);
> +
> +	return val;
> +}
> +
> +static void imx_mu_msi_parent_mask_irq(struct irq_data *data)
> +{
> +	struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data);
> +
> +	imx_mu_xcr_rmw(msi_data, IMX_MU_RCR, 0, IMX_MU_xCR_RIEn(msi_data, data->hwirq));
> +}
> +
> +static void imx_mu_msi_parent_unmask_irq(struct irq_data *data)
> +{
> +	struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data);
> +
> +	imx_mu_xcr_rmw(msi_data, IMX_MU_RCR, IMX_MU_xCR_RIEn(msi_data, data->hwirq), 0);
> +}
> +
> +static void imx_mu_msi_parent_ack_irq(struct irq_data *data)
> +{
> +	struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data);
> +
> +	imx_mu_read(msi_data, msi_data->cfg->xRR + data->hwirq * 4);
> +}
> +
> +static struct irq_chip imx_mu_msi_irq_chip = {
> +	.name = "MU-MSI",
> +	.irq_ack = irq_chip_ack_parent,
> +};
> +
> +static struct msi_domain_ops imx_mu_msi_irq_ops = {
> +};
> +
> +static struct msi_domain_info imx_mu_msi_domain_info = {
> +	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS),
> +	.ops	= &imx_mu_msi_irq_ops,
> +	.chip	= &imx_mu_msi_irq_chip,
> +};
> +
> +static void imx_mu_msi_parent_compose_msg(struct irq_data *data,
> +					  struct msi_msg *msg)
> +{
> +	struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(data);
> +	u64 addr = msi_data->msiir_addr + 4 * data->hwirq;
> +
> +	msg->address_hi = upper_32_bits(addr);
> +	msg->address_lo = lower_32_bits(addr);
> +	msg->data = data->hwirq;
> +}
> +
> +static int imx_mu_msi_parent_set_affinity(struct irq_data *irq_data,
> +				   const struct cpumask *mask, bool force)
> +{
> +	return -EINVAL;
> +}
> +
> +static struct irq_chip imx_mu_msi_parent_chip = {
> +	.name		= "MU",
> +	.irq_mask	= imx_mu_msi_parent_mask_irq,
> +	.irq_unmask	= imx_mu_msi_parent_unmask_irq,
> +	.irq_ack	= imx_mu_msi_parent_ack_irq,
> +	.irq_compose_msi_msg	= imx_mu_msi_parent_compose_msg,
> +	.irq_set_affinity = imx_mu_msi_parent_set_affinity,
> +};
> +
> +static int imx_mu_msi_domain_irq_alloc(struct irq_domain *domain,
> +					unsigned int virq,
> +					unsigned int nr_irqs,
> +					void *args)
> +{
> +	struct imx_mu_msi *msi_data = domain->host_data;
> +	unsigned long flags;
> +	int pos, err = 0;
> +
> +	WARN_ON(nr_irqs != 1);
> +
> +	spin_lock_irqsave(&msi_data->lock, flags);
> +	pos = find_first_zero_bit(&msi_data->used, IMX_MU_CHANS);
> +	if (pos < IMX_MU_CHANS)
> +		__set_bit(pos, &msi_data->used);
> +	else
> +		err = -ENOSPC;
> +	spin_unlock_irqrestore(&msi_data->lock, flags);
> +
> +	if (err)
> +		return err;
> +
> +	irq_domain_set_info(domain, virq, pos,
> +			    &imx_mu_msi_parent_chip, msi_data,
> +			    handle_edge_irq, NULL, NULL);
> +	return 0;
> +}
> +
> +static void imx_mu_msi_domain_irq_free(struct irq_domain *domain,
> +				       unsigned int virq, unsigned int nr_irqs)
> +{
> +	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
> +	struct imx_mu_msi *msi_data = irq_data_get_irq_chip_data(d);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&msi_data->lock, flags);
> +	__clear_bit(d->hwirq, &msi_data->used);
> +	spin_unlock_irqrestore(&msi_data->lock, flags);
> +}
> +
> +static const struct irq_domain_ops imx_mu_msi_domain_ops = {
> +	.alloc	= imx_mu_msi_domain_irq_alloc,
> +	.free	= imx_mu_msi_domain_irq_free,
> +};
> +
> +static void imx_mu_msi_irq_handler(struct irq_desc *desc)
> +{
> +	struct imx_mu_msi *msi_data = irq_desc_get_handler_data(desc);
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	u32 status;
> +	int i;
> +
> +	status = imx_mu_read(msi_data, msi_data->cfg->xSR[IMX_MU_RSR]);
> +
> +	chained_irq_enter(chip, desc);
> +	for (i = 0; i < IMX_MU_CHANS; i++) {
> +		if (status & IMX_MU_xSR_RFn(msi_data, i))
> +			generic_handle_domain_irq(msi_data->msi_domain, i);
> +	}
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int imx_mu_msi_domains_init(struct imx_mu_msi *msi_data, struct device *dev)
> +{
> +	struct fwnode_handle *fwnodes = dev_fwnode(dev);
> +	struct irq_domain *parent;
> +
> +	/* Initialize MSI domain parent */
> +	parent = irq_domain_create_linear(fwnodes,
> +					    IMX_MU_CHANS,
> +					    &imx_mu_msi_domain_ops,
> +					    msi_data);
> +	if (!parent) {
> +		dev_err(dev, "failed to create IRQ domain\n");
> +		return -ENOMEM;
> +	}
> +
> +	irq_domain_update_bus_token(parent, DOMAIN_BUS_NEXUS);
> +
> +	msi_data->msi_domain = platform_msi_create_irq_domain(
> +				fwnodes,
> +				&imx_mu_msi_domain_info,
> +				parent);

nit: move the first argument after the opening bracket (longer lines
are fine).

> +
> +	if (!msi_data->msi_domain) {
> +		dev_err(dev, "failed to create MSI domain\n");
> +		irq_domain_remove(parent);
> +		return -ENOMEM;
> +	}
> +
> +	irq_domain_set_pm_device(msi_data->msi_domain, dev);
> +
> +	return 0;
> +}
> +
> +/* Register offset of different version MU IP */
> +static const struct imx_mu_dcfg imx_mu_cfg_imx6sx = {

Why doesn't this have a type?

> +	.xTR    = 0x0,
> +	.xRR    = 0x10,
> +	.xSR    = {0x20, 0x20, 0x20, 0x20},

Since you defined enums for all the register offsets, please be
consistent and use them everywhere:

	.xSR = {
		[IMX_MU_SR]	= 0x20,
		[IMX_MU_GSR]	= 0x20,
		[...]
	},

> +	.xCR    = {0x24, 0x24, 0x24, 0x24},
> +};
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx7ulp = {
> +	.xTR    = 0x20,
> +	.xRR    = 0x40,
> +	.xSR    = {0x60, 0x60, 0x60, 0x60},
> +	.xCR    = {0x64, 0x64, 0x64, 0x64},
> +};
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx8ulp = {
> +	.type   = IMX_MU_V2,
> +	.xTR    = 0x200,
> +	.xRR    = 0x280,
> +	.xSR    = {0xC, 0x118, 0x124, 0x12C},
> +	.xCR    = {0x110, 0x114, 0x120, 0x128},
> +};
> +
> +static const struct imx_mu_dcfg imx_mu_cfg_imx8ulp_s4 = {
> +
> +	.type   = IMX_MU_V2 | IMX_MU_V2_S4,
> +	.xTR    = 0x200,
> +	.xRR    = 0x280,
> +	.xSR    = {0xC, 0x118, 0x124, 0x12C},
> +	.xCR    = {0x110, 0x114, 0x120, 0x128},
> +};
> +
> +static int __init imx_mu_of_init(struct device_node *dn,
> +				 struct device_node *parent,
> +				 const struct imx_mu_dcfg *cfg
> +				)

Move closing bracket after 'cfg'.

> +{
> +	struct platform_device *pdev = of_find_device_by_node(dn);
> +	struct device_link *pd_link_a;
> +	struct device_link *pd_link_b;
> +	struct imx_mu_msi *msi_data;
> +	struct resource *res;
> +	struct device *pd_a;
> +	struct device *pd_b;
> +	struct device *dev;
> +	int ret;
> +	int irq;
> +
> +	if (!pdev)
> +		return -ENODEV;

How can that happen?

> +
> +	dev = &pdev->dev;
> +
> +	msi_data = devm_kzalloc(&pdev->dev, sizeof(*msi_data), GFP_KERNEL);
> +	if (!msi_data)
> +		return -ENOMEM;
> +
> +	msi_data->cfg = cfg;
> +
> +	msi_data->regs = devm_platform_ioremap_resource_byname(pdev, "processor-a-side");
> +	if (IS_ERR(msi_data->regs)) {
> +		dev_err(&pdev->dev, "failed to initialize 'regs'\n");
> +		return PTR_ERR(msi_data->regs);
> +	}
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "processor-b-side");
> +	if (!res)
> +		return -EIO;
> +
> +	msi_data->msiir_addr = res->start + msi_data->cfg->xTR;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq <= 0)
> +		return -ENODEV;
> +
> +	platform_set_drvdata(pdev, msi_data);
> +
> +	msi_data->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(msi_data->clk)) {
> +		if (PTR_ERR(msi_data->clk) != -ENOENT)
> +			return PTR_ERR(msi_data->clk);
> +
> +		msi_data->clk = NULL;

Why is it acceptable to continue with no clock?

> +	}
> +
> +	pd_a = dev_pm_domain_attach_by_name(dev, "processor-a-side");
> +	if (IS_ERR(pd_a))
> +		return PTR_ERR(pd_a);
> +
> +	pd_b = dev_pm_domain_attach_by_name(dev, "processor-b-side");
> +	if (IS_ERR(pd_b))
> +		return PTR_ERR(pd_b);
> +
> +	pd_link_a = device_link_add(dev, pd_a,
> +			DL_FLAG_STATELESS |
> +			DL_FLAG_PM_RUNTIME |
> +			DL_FLAG_RPM_ACTIVE);
> +
> +	if (!pd_link_a) {
> +		dev_err(dev, "Failed to add device_link to mu a.\n");
> +		goto err_pd_a;
> +	}
> +
> +	pd_link_b = device_link_add(dev, pd_b,
> +			DL_FLAG_STATELESS |
> +			DL_FLAG_PM_RUNTIME |
> +			DL_FLAG_RPM_ACTIVE);
> +
> +
> +	if (!pd_link_b) {
> +		dev_err(dev, "Failed to add device_link to mu a.\n");
> +		goto err_pd_b;
> +	}
> +
> +	ret = imx_mu_msi_domains_init(msi_data, dev);
> +	if (ret)
> +		goto err_dm_init;
> +
> +	irq_set_chained_handler_and_data(irq,
> +					 imx_mu_msi_irq_handler,
> +					 msi_data);
> +
> +	pm_runtime_enable(dev);

Shouldn't you enable the device PM before registering the chained
handler?

	M.

-- 
Without deviation from the norm, progress is not possible.