Subject: [PATCH v3 3/5] pci: altera: Add Altera PCIe MSI driver

From: [email-masked] (Marc Zyngier)
Date: Fri, 07 Aug 2015 15:44:24 +0100

On 07/08/15 08:43, Ley Foon Tan wrote:
> This patch adds Altera PCIe MSI driver. This soft IP supports configurable
> number of vectors, which is a dts parameter.
> 
> Signed-off-by: Ley Foon Tan <[email-masked]>
> ---
>  drivers/pci/host/Kconfig           |   8 +
>  drivers/pci/host/Makefile          |   1 +
>  drivers/pci/host/pcie-altera-msi.c | 309 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 318 insertions(+)
>  create mode 100644 drivers/pci/host/pcie-altera-msi.c
> 
> diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
> index 4b4754a..d28cc6d 100644
> --- a/drivers/pci/host/Kconfig
> +++ b/drivers/pci/host/Kconfig
> @@ -152,4 +152,12 @@ config PCIE_ALTERA
>           Say Y here if you want to enable PCIe controller support for Altera
>           SoCFPGA family of SoCs.
> 
> +config PCIE_ALTERA_MSI
> +       bool "Altera PCIe MSI feature"
> +       depends on PCI_MSI
> +       select PCI_MSI_IRQ_DOMAIN
> +       help
> +         Say Y here if you want PCIe MSI support for the Altera SocFPGA SoC.
> +         This MSI driver supports Altera MSI to GIC controller IP.
> +
>  endmenu
> diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
> index 6954f76..6c4913d 100644
> --- a/drivers/pci/host/Makefile
> +++ b/drivers/pci/host/Makefile
> @@ -18,3 +18,4 @@ obj-$(CONFIG_PCIE_IPROC) += pcie-iproc.o
>  obj-$(CONFIG_PCIE_IPROC_PLATFORM) += pcie-iproc-platform.o
>  obj-$(CONFIG_PCIE_IPROC_BCMA) += pcie-iproc-bcma.o
>  obj-$(CONFIG_PCIE_ALTERA) += pcie-altera.o
> +obj-$(CONFIG_PCIE_ALTERA_MSI) += pcie-altera-msi.o
> diff --git a/drivers/pci/host/pcie-altera-msi.c b/drivers/pci/host/pcie-altera-msi.c
> new file mode 100644
> index 0000000..2d84e62
> --- /dev/null
> +++ b/drivers/pci/host/pcie-altera-msi.c
> @@ -0,0 +1,309 @@
> +/*
> + * Copyright Altera Corporation (C) 2013-2015. All rights reserved
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +#include <linux/interrupt.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_pci.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define MSI_STATUS             0x0
> +#define MSI_ERROR              0x4
> +#define MSI_INTMASK            0x8
> +
> +#define MAX_MSI_VECTORS                32
> +struct altera_msi {
> +       DECLARE_BITMAP(used, MAX_MSI_VECTORS);
> +       struct mutex            lock;   /* proctect used variable */
> +       struct platform_device  *pdev;
> +       struct irq_domain               *msi_domain;
> +       struct irq_domain               *inner_domain;
> +       void __iomem            *csr_base;
> +       void __iomem            *vector_base;
> +       phys_addr_t             vector_phy;
> +       u32                     num_of_vectors;
> +       int                     irq;
> +};
> +
> +static inline void msi_writel(struct altera_msi *msi, u32 value, u32 reg)
> +{
> +       writel_relaxed(value, msi->csr_base + reg);
> +}
> +
> +static inline u32 msi_readl(struct altera_msi *msi, u32 reg)
> +{
> +       return readl_relaxed(msi->csr_base + reg);
> +}
> +
> +static void altera_msi_isr(unsigned int irq, struct irq_desc *desc)
> +{
> +       struct irq_chip *chip = irq_desc_get_chip(desc);
> +       struct altera_msi *msi;
> +       unsigned long status;
> +       u32 num_of_vectors;
> +       u32 bit;
> +       u32 virq;
> +
> +       chained_irq_enter(chip, desc);
> +       msi = irq_desc_get_handler_data(desc);
> +       num_of_vectors = msi->num_of_vectors;
> +
> +       do {
> +               status = msi_readl(msi, MSI_STATUS);
> +               if (!status)
> +                       break;
> +
> +               do {
> +                       bit = find_first_bit(&status, num_of_vectors);
> +                       /* Dummy read from vector to clear the interrupt */
> +                       readl_relaxed(msi->vector_base + (bit * sizeof(u32)));
> +
> +                       virq = irq_find_mapping(msi->inner_domain, bit);
> +                       if (virq && test_bit(bit, msi->used))
> +                               generic_handle_irq(virq);
> +                       else
> +                               dev_err(&msi->pdev->dev, "unexpected MSI\n");
> +
> +                       /* Clear the bit from status and repeat without reading
> +                        * again status register. */
> +                       __clear_bit(bit, &status);
> +               } while (status);
> +       } while (1);
> +
> +       chained_irq_exit(chip, desc);
> +}
> +
> +static struct irq_chip altera_msi_irq_chip = {
> +       .name = "Altera PCIe MSI",
> +       .irq_enable = pci_msi_unmask_irq,
> +       .irq_disable = pci_msi_mask_irq,
> +       .irq_mask = pci_msi_mask_irq,
> +       .irq_unmask = pci_msi_unmask_irq,
> +};
> +
> +static struct msi_domain_info altera_msi_domain_info = {
> +       .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> +                    MSI_FLAG_PCI_MSIX),
> +       .chip   = &altera_msi_irq_chip,
> +};
> +
> +static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +       struct altera_msi *msi = irq_data_get_irq_chip_data(data);
> +       phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
> +
> +       msg->address_lo = lower_32_bits(addr);
> +       msg->address_hi = upper_32_bits(addr);
> +       msg->data = data->hwirq;
> +
> +       dev_dbg(&msi->pdev->dev, "msi#%d address_lo 0x%x address_hi 0x%x\n",
> +               (int)data->hwirq, msg->address_hi, msg->address_lo);
> +}
> +
> +static int altera_msi_set_affinity(struct irq_data *irq_data,
> +                                  const struct cpumask *mask, bool force)
> +{
> +        return -EINVAL;
> +}
> +
> +static struct irq_chip altera_msi_bottom_irq_chip = {
> +       .name                   = "Altera MSI",
> +       .irq_compose_msi_msg    = altera_compose_msi_msg,
> +       .irq_set_affinity       = altera_msi_set_affinity,
> +};
> +
> +static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
> +                                  unsigned int nr_irqs, void *args)
> +{
> +       struct altera_msi *msi = domain->host_data;
> +       unsigned long bit;
> +       u32 mask;
> +

As you cannot support multi-MSI, it would be good to have a
WARN_ON(nr_irqs != 1) here. Just in case...

> +       mutex_lock(&msi->lock);
> +
> +       bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
> +       if (bit >= msi->num_of_vectors)
> +               return -ENOSPC;
> +
> +       set_bit(bit, msi->used);
> +
> +       mutex_unlock(&msi->lock);
> +
> +       irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
> +                           domain->host_data, handle_simple_irq,
> +                           NULL, NULL);
> +       set_irq_flags(virq, IRQF_VALID);
> +
> +       mask = msi_readl(msi, MSI_INTMASK);
> +       mask |= 1 << bit;
> +       msi_writel(msi, mask, MSI_INTMASK);
> +
> +       return 0;
> +}
> +
> +static void altera_irq_domain_free(struct irq_domain *domain,
> +                                  unsigned int virq, unsigned int nr_irqs)
> +{
> +       struct irq_data *d = irq_domain_get_irq_data(domain, virq);
> +       struct altera_msi *msi = irq_data_get_irq_chip_data(d);
> +       u32 mask;
> +
> +       mutex_lock(&msi->lock);
> +
> +       if (!test_bit(d->hwirq, msi->used)) {
> +               dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
> +                       d->hwirq);
> +       } else {
> +               __clear_bit(d->hwirq, msi->used);
> +               mask = msi_readl(msi, MSI_INTMASK);
> +               mask &= ~(1 << d->hwirq);
> +               msi_writel(msi, mask, MSI_INTMASK);
> +       }
> +
> +       mutex_unlock(&msi->lock);
> +}
> +
> +static const struct irq_domain_ops msi_domain_ops = {
> +       .alloc  = altera_irq_domain_alloc,
> +       .free   = altera_irq_domain_free,
> +};
> +
> +static int altera_allocate_domains(struct altera_msi *msi)
> +{
> +       msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
> +                                            &msi_domain_ops, msi);
> +       if (!msi->inner_domain) {
> +               dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
> +               return -ENOMEM;
> +       }
> +
> +       msi->msi_domain = pci_msi_create_irq_domain(msi->pdev->dev.of_node,
> +                               &altera_msi_domain_info, msi->inner_domain);
> +       if (!msi->msi_domain) {
> +               dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
> +               irq_domain_remove(msi->inner_domain);
> +               return -ENOMEM;
> +       }
> +
> +       return 0;
> +}
> +
> +static void altera_free_domains(struct altera_msi *msi)
> +{
> +       irq_domain_remove(msi->msi_domain);
> +       irq_domain_remove(msi->inner_domain);
> +}
> +
> +static int altera_msi_remove(struct platform_device *pdev)
> +{
> +       struct altera_msi *msi = platform_get_drvdata(pdev);
> +
> +       msi_writel(msi, 0, MSI_INTMASK);
> +       irq_set_chained_handler(msi->irq, NULL);
> +       irq_set_handler_data(msi->irq, NULL);
> +
> +       altera_free_domains(msi);
> +
> +       platform_set_drvdata(pdev, NULL);
> +       return 0;
> +}
> +
> +static int altera_msi_probe(struct platform_device *pdev)
> +{
> +       struct altera_msi *msi;
> +       struct device_node *np = pdev->dev.of_node;
> +       struct resource *res;
> +       int ret;
> +
> +       msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
> +                          GFP_KERNEL);
> +       if (!msi)
> +               return -ENOMEM;
> +
> +       mutex_init(&msi->lock);
> +       msi->pdev = pdev;
> +
> +       res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "csr");

Error checking here.

> +       msi->csr_base = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(msi->csr_base)) {
> +               dev_err(&pdev->dev, "get csr resource failed\n");
> +               return PTR_ERR(msi->csr_base);
> +       }
> +
> +       res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +                                          "vector_slave");

And here.

> +       msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(msi->vector_base)) {
> +               dev_err(&pdev->dev, "get vector slave resource failed\n");
> +               return PTR_ERR(msi->vector_base);
> +       }
> +
> +       msi->vector_phy = res->start;
> +
> +       if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
> +               dev_err(&pdev->dev, "failed to parse the number of vectors\n");
> +               return -EINVAL;
> +       }
> +
> +       ret = altera_allocate_domains(msi);
> +       if (ret)
> +               return ret;
> +
> +       msi->irq = platform_get_irq(pdev, 0);
> +       if (msi->irq <= 0) {
> +               dev_err(&pdev->dev, "failed to map IRQ: %d\n", msi->irq);
> +               ret = -ENODEV;
> +               goto err;
> +       }
> +
> +       irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
> +       platform_set_drvdata(pdev, msi);
> +
> +       return 0;
> +
> +err:
> +       altera_msi_remove(pdev);
> +       return ret;
> +}
> +
> +static const struct of_device_id altera_msi_of_match[] = {
> +       { .compatible = "altr,msi-1.0", NULL },
> +       { },
> +};
> +
> +static struct platform_driver altera_msi_driver = {
> +       .driver = {
> +               .name = "altera-msi",
> +               .of_match_table = altera_msi_of_match,
> +       },
> +       .probe = altera_msi_probe,
> +       .remove = altera_msi_remove,
> +};
> +
> +static int __init altera_msi_init(void)
> +{
> +       return platform_driver_register(&altera_msi_driver);
> +}
> +
> +subsys_initcall(altera_msi_init);
> +
> +MODULE_AUTHOR("Ley Foon Tan <[email-masked]>");
> +MODULE_DESCRIPTION("Altera PCIe MSI support");
> +MODULE_LICENSE("GPL v2");
> --
> 1.8.2.1
> 

Apart from the couple of nits above, this is starting to look good too.
And as for the PCIe driver, you need to get the DT maintainers to review
that part.

Thanks,

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