On Fri, Jul 31, 2015 at 8:12 PM, Marc Zyngier [off-list ref] wrote:

On 31/07/15 11:15, Ley Foon Tan wrote:

quoted

This patch adds Altera PCIe MSI driver. This soft IP supports configurable
number of vectors, which is a dts parameter.

I've reviewed the initial drop of this code; basic courtesy would be to
keep me CCed on the follow-up series.

Will keep you in CC for the following revision. Sorry about this.

quoted

Signed-off-by: Ley Foon Tan <redacted>
---
 drivers/pci/host/Kconfig           |   7 +
 drivers/pci/host/Makefile          |   1 +
 drivers/pci/host/pcie-altera-msi.c | 324 +++++++++++++++++++++++++++++++++++++
 3 files changed, 332 insertions(+)
 create mode 100644 drivers/pci/host/pcie-altera-msi.c

diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index 108500a..51d0468 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig

@@ -153,4 +153,11 @@ 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
+     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..6014719
--- /dev/null
+++ b/drivers/pci/host/pcie-altera-msi.c

@@ -0,0 +1,324 @@
+/*
+ * 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;
+
+     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)));
+
+                     irq = irq_find_mapping(msi->inner_domain, bit);

Use of irq is a bit confusing, as this is a parameter describing the
chaining interrupt. Consider using a different name for this variable.

Okay, will change it to 'virq'.

quoted

+                     if (irq) {
+                             if (test_bit(bit, msi->used))
+                                     generic_handle_irq(irq);
+                             else
+                                     dev_info(&msi->pdev->dev, "unhandled MSI\n");
+                     } else
+                             dev_info(&msi->pdev->dev, "unexpected MSI\n");

The whole statement could be rewritten as:

if (irq && test_bit(bit, msi->used))
        generic_handle_irq(irq);
else
        dev_err(...);

In all cases, this is a grave error, so dev_info is not appropriate here.

Noted.

quoted

+
+                     /* Clear the bit from status and repeat without reading
+                      * again status register. */
+                     clear_bit(bit, &status);

You don't need an atomic operation here, so __clear_bit() should be enough.

Noted.

quoted

+             } 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)
+{
+     u32 mask;
+     struct altera_msi *msi = irq_data_get_irq_chip_data(data);
+     u64 addr = msi->vector_phy + (data->hwirq * sizeof(u32));

Use phys_addr_t.

Noted.

quoted

+
+     msg->address_lo = lower_32_bits(addr);
+     msg->address_hi = upper_32_bits(addr);
+     msg->data = data->hwirq;
+
+     mask = msi_readl(msi, MSI_INTMASK);
+     mask |= 1 << data->hwirq;
+     msi_writel(msi, mask, MSI_INTMASK);

It feels a bit weird to unmask the interrupt when you compose the
message. I'd expect this to be done in the mask/unmask methods.

Do you refer to these 2 callbacks?
.irq_mask = pci_msi_mask_irq,
.irq_unmask = pci_msi_unmask_irq,

How about we move this INTMASK code above to altera_irq_domain_alloc()?
We have unmask code in altera_irq_domain_free() now.

quoted

+     dev_dbg(&msi->pdev->dev, "msi#%d address_lo 0x%x\n", (int)data->hwirq,
+             msg->address_lo);

You may want to print the whole address here.

Noted.

quoted

+}
+
+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;
+     int bit;
+
+     mutex_lock(&msi->lock);
+
+     bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
+     if (bit < msi->num_of_vectors)
+             set_bit(bit, msi->used);
+
+     mutex_unlock(&msi->lock);
+
+     if (bit < 0)
+             return bit;

How can "bit" be negative here? find_first_zero_bit returns an unsigned
long... You probably want to change the type of "bit" to reflect that.

Okay, will change to "unsigned long" type.

quoted

+     else if (bit >= msi->num_of_vectors)

Useless "else" anyway.

I think we still need to check for failing case, if we don't have
available unused bit.
This could be rewritten  as below:

bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
if (bit < msi->num_of_vectors)
      set_bit(bit, msi->used);
else
      return -ENOSPC;

quoted

+             return -ENOSPC;
+
+     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);
+
+     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);

Put this statement in { } so that it matches the "else" construct.

Noted.

quoted

+     else {
+             clear_bit(d->hwirq, msi->used);

No need for an atomic operation here, you own the mutex.

Okay, change to __clear_bit.

quoted

+             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,

Please put at least one argument to the function on the same line. This
is otherwise very hard to read.

Okay.

quoted

+                             &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;
+}
+
+int altera_msi_probe(struct platform_device *pdev)

Make this static.

Okay.

quoted

+{
+     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");
+     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");
+     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(msi->irq, altera_msi_isr);
+     ret = irq_set_handler_data(msi->irq, msi);

Use irq_set_chained_handler_and_data.

Okay.

quoted

+     if (ret) {
+             dev_err(&pdev->dev, "failed to register IRQ handler: %d\n",
+                     ret);
+             goto err;
+     }
+
+     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 },
+     { },
+};
+MODULE_DEVICE_TABLE(of, altera_msi_of_match);
+
+static struct platform_driver altera_msi_driver = {
+     .driver = {
+             .name = "altera-msi",
+             .owner = THIS_MODULE,

Remove this .owner assignment, the core code deals with it.

Okay.

quoted

+             .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);

Hmmm. if you're initializing this as part of the core kernel, it will
never be a module. What is the point of the MODULE_DEVICE_TABLE above?

Okay, will remove MODULE_DEVICE_TABLE.

Thanks for reviewing.

Regards
Ley Foon