Re: [PATCH 2/2] arm/gic: Add supports for GICv2m MSI(-X)

From: Marc Zyngier
Date: Tue Jun 24 2014 - 05:52:27 EST

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Hi Suravee,

On 24/06/14 01:33, suravee.suthikulpanit@xxxxxxx wrote:
> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
>
> GICv2m extends GICv2 to support MSI(-X) with a new set of register frames.
>
> This patch introduces support for the non-secure GICv2m register frame.
> This is optional. It uses the "msi-controller" keyword in ARM GIC
> devicetree binding to indentify GIC driver that it should enable MSI(-X)
> support, The region of GICv2m MSI register frame is specified using the register
> frame index 4 in the device tree.
>
> Each GIC maintains an "msi_chip" structure. To discover the msi_chip,
> PCI host driver can do the following:
>
> struct device_node *gic_node = of_irq_find_parent(pdev->dev.of_node);
> pcie_bus->msi_chip = of_pci_find_msi_chip_by_node(gic_node);
>
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
> ---
> Documentation/devicetree/bindings/arm/gic.txt | 18 +-
> drivers/irqchip/Kconfig | 6 +
> drivers/irqchip/Makefile | 1 +
> drivers/irqchip/gic-msi-v2m.c | 249 ++++++++++++++++++++++++++
> drivers/irqchip/gic-msi-v2m.h | 20 +++
> drivers/irqchip/irq-gic.c | 21 ++-
> 6 files changed, 311 insertions(+), 4 deletions(-)
> create mode 100644 drivers/irqchip/gic-msi-v2m.c
> create mode 100644 drivers/irqchip/gic-msi-v2m.h
>
> diff --git a/Documentation/devicetree/bindings/arm/gic.txt b/Documentation/devicetree/bindings/arm/gic.txt
> index 5573c08..ee4bc02 100644
> --- a/Documentation/devicetree/bindings/arm/gic.txt
> +++ b/Documentation/devicetree/bindings/arm/gic.txt
> @@ -17,6 +17,7 @@ Main node required properties:
> "arm,cortex-a7-gic"
> "arm,arm11mp-gic"
> - interrupt-controller : Identifies the node as an interrupt controller
> +
> - #interrupt-cells : Specifies the number of cells needed to encode an
> interrupt source. The type shall be a <u32> and the value shall be 3.
>
> @@ -37,9 +38,16 @@ Main node required properties:
> the 8 possible cpus attached to the GIC. A bit set to '1' indicated
> the interrupt is wired to that CPU. Only valid for PPI interrupts.
>
> -- reg : Specifies base physical address(s) and size of the GIC registers. The
> - first region is the GIC distributor register base and size. The 2nd region is
> - the GIC cpu interface register base and size.
> +- reg : Specifies base physical address(s) and size of the GIC register frames.
> +
> + Region | Description
> + Index |
> + -------------------------------------------------------------------
> + 0 | GIC distributor register base and size
> + 1 | GIC cpu interface register base and size
> + 2 | VGIC interface control register base and size (Optional)
> + 3 | VGIC CPU interface register base and size (Optional)
> + 4 | GICv2m MSI interface register base and size (Optional)
>
> Optional
> - interrupts : Interrupt source of the parent interrupt controller on
> @@ -55,6 +63,10 @@ Optional
> by a crossbar/multiplexer preceding the GIC. The GIC irq
> input line is assigned dynamically when the corresponding
> peripheral's crossbar line is mapped.
> +
> +- msi-controller : Identifies the node as an MSI controller. This requires
> + the register region index 4.
> +
> Example:
>
> intc: interrupt-controller@fff11000 {
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index bbb746e..a36bf94 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -7,6 +7,12 @@ config ARM_GIC
> select IRQ_DOMAIN
> select MULTI_IRQ_HANDLER
>
> +config ARM_GIC_MSI_V2M
> + bool
> + select IRQ_DOMAIN
> + select MULTI_IRQ_HANDLER
> + depends on PCI && PCI_MSI
> +
> config GIC_NON_BANKED
> bool
>
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 62a13e5..d43f904 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_ARCH_SUNXI) += irq-sun4i.o
> obj-$(CONFIG_ARCH_SUNXI) += irq-sunxi-nmi.o
> obj-$(CONFIG_ARCH_SPEAR3XX) += spear-shirq.o
> obj-$(CONFIG_ARM_GIC) += irq-gic.o
> +obj-$(CONFIG_ARM_GIC_MSI_V2M) += gic-msi-v2m.o
> obj-$(CONFIG_ARM_NVIC) += irq-nvic.o
> obj-$(CONFIG_ARM_VIC) += irq-vic.o
> obj-$(CONFIG_IMGPDC_IRQ) += irq-imgpdc.o
> diff --git a/drivers/irqchip/gic-msi-v2m.c b/drivers/irqchip/gic-msi-v2m.c
> new file mode 100644
> index 0000000..e5c0f79
> --- /dev/null
> +++ b/drivers/irqchip/gic-msi-v2m.c
> @@ -0,0 +1,249 @@
> +/*
> + * ARM GIC v2m MSI support
> + * Support for Message Signalelled Interrupts for systems that
> + * implement ARM Generic Interrupt Controller: GICv2m.
> + *
> + * Copyright (C) 2014 Advanced Micro Devices, Inc.
> + * Authors: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> + * Harish Kasiviswanathan <harish.kasiviswanathan@xxxxxxx>
> + * Brandon Anderson <brandon.anderson@xxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> + * by the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pci.h>
> +#include <linux/irq.h>
> +#include <linux/spinlock.h>
> +#include <linux/slab.h>
> +#include <linux/of_address.h>
> +#include <linux/bitmap.h>
> +
> +#include "gic-msi-v2m.h"
> +
> +/* GICv2m MSI Registers */
> +#define MSI_TYPER 0x008
> +#define MSI_SETSPI_NS 0x040
> +#define GIC_V2M_MIN_SPI 32
> +#define GIC_V2M_MAX_SPI 1024
> +#define GIC_OF_MSIV2M_RANGE_INDEX 4
> +
> +extern struct irq_chip gic_arch_extn;
> +
> +/**
> + * alloc_msi_irq - Allocate MSIs from avaialbe MSI bitmap.
> + * @data: Pointer to gicv2m_msi_data
> + * @nvec: Number of interrupts to allocate
> + * @irq: Pointer to the allocated irq
> + *
> + * Allocates interrupts only if the contiguous range of MSIs
> + * with specified nvec are avaiable. Otherwise return the number
> + * of avaiable interrupts. If none is avaiable, then returns -ENOENT.
> + */
> +static int alloc_msi_irq(struct gicv2m_msi_data *data, int nvec, int *irq)
> +{
> + int size = sizeof(unsigned long) * data->bm_sz;
> + int next = size, ret, num;
> +
> + spin_lock(&data->msi_cnt_lock);
> +
> + for (num = nvec; num > 0; num--) {
> + next = bitmap_find_next_zero_area(data->bm,
> + size, 0, num, 0);
> + if (next < size)
> + break;
> + }
> +
> + if (next < size) {
> + bitmap_set(data->bm, next, nvec);
> + *irq = data->spi_start + next;
> + ret = 0;
> + } else if (num != 0) {
> + ret = num;
> + } else {
> + ret = -ENOENT;
> + }
> +
> +
> + spin_unlock(&data->msi_cnt_lock);
> +
> + return ret;
> +}
> +
> +static void free_msi_irq(struct gicv2m_msi_data *data, unsigned int irq)
> +{
> + int pos;
> +
> + spin_lock(&data->msi_cnt_lock);
> +
> + pos = irq - data->spi_start;
> + if (pos >= 0 && pos < data->max_spi_cnt)
> + bitmap_clear(data->bm, pos, 1);
> +
> + spin_unlock(&data->msi_cnt_lock);
> +}
> +
> +static inline struct gicv2m_msi_data *to_gicv2m_msi_data(struct msi_chip *chip)
> +{
> + return container_of(chip, struct gicv2m_msi_data, chip);
> +}
> +
> +static void gicv2m_teardown_msi_irq(struct msi_chip *chip, unsigned int irq)
> +{
> + free_msi_irq(to_gicv2m_msi_data(chip), irq);
> +}
> +
> +static int gicv2m_setup_msi_irq(struct msi_chip *chip, struct pci_dev *pdev,
> + struct msi_desc *desc)
> +{
> + int avail, irq = 0;
> + struct msi_msg msg;
> + phys_addr_t addr;
> + struct gicv2m_msi_data *data = to_gicv2m_msi_data(chip);
> +
> + if (data == NULL) {
> + dev_err(&pdev->dev,
> + "GICv2m: MSI setup failed. Invalid platform data\n");
> + return -EINVAL;
> + }
> +
> + if (!desc) {
> + dev_err(&pdev->dev,
> + "GICv2m: MSI setup failed. Invalid msi descriptor\n");
> + return -EINVAL;
> + }
> +
> + avail = alloc_msi_irq(data, 1, &irq);
> + if (avail != 0) {
> + dev_err(&pdev->dev,
> + "GICv2m: MSI setup failed. Cannnot allocate IRQ\n");
> + return -ENOSPC;
> + }
> +
> + irq_set_msi_desc(irq, desc);
> + irq_set_irq_type(irq, IRQ_TYPE_EDGE_RISING);
> +
> + addr = (unsigned long)(data->paddr64 + MSI_SETSPI_NS);
> +
> + msg.address_hi = (unsigned int)(addr >> 32);
> + msg.address_lo = (unsigned int)(addr);
> + msg.data = irq;
> +#ifdef CONFIG_PCI_MSI
> + write_msi_msg(irq, &msg);
> +#endif
> +
> + return 0;
> +}
> +
> +static void gicv2m_mask_msi(struct irq_data *d)
> +{
> + if (d->msi_desc)
> + mask_msi_irq(d);
> +}

Under which circumstance can d->msi_desc be NULL? Why should we care?

> +static void gicv2m_unmask_msi(struct irq_data *d)
> +{
> + if (d->msi_desc)
> + unmask_msi_irq(d);
> +}
> +
> +int __init gicv2m_msi_init(struct device_node *node,
> + struct gicv2m_msi_data *msi)
> +{
> + unsigned int val;
> + const __be32 *msi_be;
> +
> + msi_be = of_get_address(node, GIC_OF_MSIV2M_RANGE_INDEX, NULL, NULL);
> + if (!msi_be) {
> + pr_err("GICv2m failed. Fail to locate MSI base.\n");
> + return -EINVAL;
> + }
> +
> + msi->paddr64 = of_translate_address(node, msi_be);
> + msi->base = of_iomap(node, GIC_OF_MSIV2M_RANGE_INDEX);
> +
> + /*
> + * MSI_TYPER:
> + * [31:26] Reserved
> + * [25:16] lowest SPI assigned to MSI
> + * [15:10] Reserved
> + * [9:0] Numer of SPIs assigned to MSI
> + */
> + val = __raw_readl(msi->base + MSI_TYPER);
> + if (!val) {
> + pr_warn("GICv2m: Failed to read MSI_TYPER register\n");
> + return -EINVAL;
> + }
> +
> + msi->spi_start = (val >> 16) & 0x3ff;
> + msi->max_spi_cnt = val & 0x3ff;
> +
> + pr_debug("GICv2m: SPI = %u, cnt = %u\n",
> + msi->spi_start, msi->max_spi_cnt);
> +
> + if (msi->spi_start < GIC_V2M_MIN_SPI ||
> + msi->max_spi_cnt >= GIC_V2M_MAX_SPI) {
> + pr_err("GICv2m: Init failed\n");
> + return -EINVAL;
> + }
> +
> + msi->bm_sz = BITS_TO_LONGS(msi->max_spi_cnt);
> + msi->bm = kzalloc(msi->bm_sz, GFP_KERNEL);
> + if (!msi->bm)
> + return -ENOMEM;
> +
> + spin_lock_init(&msi->msi_cnt_lock);
> +
> + msi->chip.owner = THIS_MODULE;
> + msi->chip.of_node = node;
> + msi->chip.setup_irq = gicv2m_setup_msi_irq;
> + msi->chip.teardown_irq = gicv2m_teardown_msi_irq;
> +
> + pr_info("GICv2m: SPI range [%d:%d]\n",
> + msi->spi_start, (msi->spi_start + msi->max_spi_cnt));
> +
> + gic_arch_extn.irq_mask = gicv2m_mask_msi;
> + gic_arch_extn.irq_unmask = gicv2m_unmask_msi;

Right, I now see why you need to test on the MSI descriptor. Don't do
that. The gic_arch_extn crap should *never* *be* *used*.

What you want to do is do assign a different irq_chip to your MSI
interrupts. This will require a different integration with the main GIC
code though. For the GICv3 ITS, I do it when the interrupt gets mapped.

> + return 0;
> +}
> +EXPORT_SYMBOL(gicv2m_msi_init);
> +
> +
> +
> +/**
> + * Override arch_setup_msi_irq in drivers/pci/msi.c
> + * since we don't want to change the chip_data
> + */
> +int arch_setup_msi_irq(struct pci_dev *pdev, struct msi_desc *desc)
> +{
> + struct msi_chip *chip = pdev->bus->msi;
> +
> + if (!chip || !chip->setup_irq)
> + return -EINVAL;
> +
> + return chip->setup_irq(chip, pdev, desc);
> +}
> +
> +/**
> + * Override arch_teardown_msi_irq in drivers/pci/msi.c
> + */
> +void arch_teardown_msi_irq(unsigned int irq)
> +{
> + struct msi_desc *desc;
> + struct msi_chip *chip;
> +
> + desc = irq_get_msi_desc(irq);
> + if (!desc)
> + return;
> +
> + chip = desc->dev->bus->msi;
> + if (!chip)
> + return;
> +
> + chip->teardown_irq(chip, irq);
> +}

Please don't overtide those. There shouldn't be any reason for a
*driver* to do so. Only architecture code should do it. And nothing in
your code requires it (at least once you've stopped playing with the
silly gic extension...).

> diff --git a/drivers/irqchip/gic-msi-v2m.h b/drivers/irqchip/gic-msi-v2m.h
> new file mode 100644
> index 0000000..164d929
> --- /dev/null
> +++ b/drivers/irqchip/gic-msi-v2m.h
> @@ -0,0 +1,20 @@
> +#ifndef GIC_MSI_V2M_H
> +#define GIC_MSI_V2M_H
> +
> +#include <linux/msi.h>
> +
> +struct gicv2m_msi_data {
> + struct msi_chip chip;
> + spinlock_t msi_cnt_lock;
> + u64 paddr64; /* GICv2m phys address */
> + void __iomem *base; /* GICv2m virt address */
> + unsigned int spi_start; /* The SPI number that MSIs start */
> + unsigned int max_spi_cnt; /* The number of SPIs for MSIs */
> + unsigned long *bm; /* MSI vector bitmap */
> + unsigned long bm_sz; /* MSI bitmap size */
> +};
> +
> +extern int gicv2m_msi_init(struct device_node *node,
> + struct gicv2m_msi_data *msi) __init;
> +
> +#endif /*GIC_MSI_V2M_H*/
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index adc86de..dcff99b 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -35,6 +35,7 @@
> #include <linux/of.h>
> #include <linux/of_address.h>
> #include <linux/of_irq.h>
> +#include <linux/of_pci.h>
> #include <linux/irqdomain.h>
> #include <linux/interrupt.h>
> #include <linux/percpu.h>
> @@ -48,6 +49,10 @@
>
> #include "irqchip.h"
>
> +#ifdef CONFIG_ARM_GIC_MSI_V2M
> +#include "gic-msi-v2m.h"
> +#endif
> +
> union gic_base {
> void __iomem *common_base;
> void __percpu * __iomem *percpu_base;
> @@ -68,6 +73,9 @@ struct gic_chip_data {
> #ifdef CONFIG_GIC_NON_BANKED
> void __iomem *(*get_base)(union gic_base *);
> #endif
> +#ifdef CONFIG_ARM_GIC_MSI_V2M
> + struct gicv2m_msi_data msi_data;
> +#endif
> };
>
> static DEFINE_RAW_SPINLOCK(irq_controller_lock);
> @@ -246,7 +254,8 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
> bool force)
> {
> void __iomem *reg = gic_dist_base(d) + GIC_DIST_TARGET + (gic_irq(d) & ~3);
> - unsigned int cpu, shift = (gic_irq(d) % 4) * 8;
> + unsigned int shift = (gic_irq(d) % 4) * 8;
> + unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask);
> u32 val, mask, bit;
>
> if (!force)
> @@ -1047,6 +1056,7 @@ gic_of_init(struct device_node *node, struct device_node *parent)
> void __iomem *dist_base;
> u32 percpu_offset;
> int irq;
> + struct gic_chip_data *gic;
>
> if (WARN_ON(!node))
> return -ENODEV;
> @@ -1068,6 +1078,15 @@ gic_of_init(struct device_node *node, struct device_node *parent)
> irq = irq_of_parse_and_map(node, 0);
> gic_cascade_irq(gic_cnt, irq);
> }
> +
> +#ifdef CONFIG_ARM_GIC_MSI_V2M
> + if (of_find_property(node, "msi-controller", NULL)) {
> + gic = &gic_data[gic_cnt];
> + if (!gicv2m_msi_init(node, &gic->msi_data))
> + of_pci_msi_chip_add(&gic->msi_data.chip);
> + }
> +#endif
> +
> gic_cnt++;
> return 0;
> }
> --
> 1.9.0
>
>

Overall, this requires to be re-architected. If you want to have a look
at the way I did the GICv3 ITS support:

git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
gicv3/its

Thanks,

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