On Thu, May 03, 2018 at 11:08:09AM +0530, Subrahmanya Lingappa wrote:
> Lorenzo,
>
> On Wed, May 2, 2018 at 8:20 PM, Lorenzo Pieralisi
> <lorenzo.pieralisi@xxxxxxx> wrote:
> >
> > On Mon, Apr 30, 2018 at 12:40:23AM -0400, Subrahmanya Lingappa wrote:
> > > Implement MSI support for Mobiveil PCIe Host Bridge IP device driver.
> > >
> > > Signed-off-by: Subrahmanya Lingappa <l.subrahmanya@xxxxxxxxxxxxxx>
> > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > > Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> > > Cc: linux-pci@xxxxxxxxxxxxxxx
> > > ---
> > > drivers/pci/host/pcie-mobiveil.c | 207 ++++++++++++++++++++++++++++++++++++++-
> > > 1 file changed, 203 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/pci/host/pcie-mobiveil.c b/drivers/pci/host/pcie-mobiveil.c
> > > index 02b1f5d..2470095 100644
> > > --- a/drivers/pci/host/pcie-mobiveil.c
> > > +++ b/drivers/pci/host/pcie-mobiveil.c
> > > @@ -14,6 +14,7 @@
> > > #include <linux/irqdomain.h>
> > > #include <linux/kernel.h>
> > > #include <linux/module.h>
> > > +#include <linux/msi.h>
> > > #include <linux/of_address.h>
> > > #include <linux/of_irq.h>
> > > #include <linux/of_platform.h>
> > > @@ -56,6 +57,7 @@
> > > #define PAB_INTP_AMBA_MISC_ENB 0x0b0c
> > > #define PAB_INTP_AMBA_MISC_STAT 0x0b1c
> > > #define PAB_INTP_INTX_MASK 0x1e0
> > > +#define PAB_INTP_MSI_MASK 0x8
> > >
> > > #define PAB_AXI_AMAP_CTRL(win) PAB_REG_ADDR(0x0ba0, win)
> > > #define WIN_ENABLE_SHIFT 0
> > > @@ -85,6 +87,17 @@
> > >
> > > /* supported number of interrupts */
> > > #define PAB_INTX_START 5
> > > +#define PCI_NUM_MSI 16
> >
> > 1 tab is enough.
> >
> > > +
> > > +/* MSI registers */
> > > +#define MSI_BASE_LO_OFFSET 0x04
> > > +#define MSI_BASE_HI_OFFSET 0x08
> > > +#define MSI_SIZE_OFFSET 0x0c
> >
> > Please make the tabs uniform (ie 1 tab).
> >
> > > +#define MSI_ENABLE_OFFSET 0x14
> > > +#define MSI_STATUS_OFFSET 0x18
> > > +#define MSI_DATA_OFFSET 0x20
> >
> > Ditto.
> >
> > > +#define MSI_ADDR_L_OFFSET 0x24
> > > +#define MSI_ADDR_H_OFFSET 0x28
> > >
> > > /* outbound and inbound window definitions */
> > > #define WIN_NUM_0 0
> > > @@ -100,11 +113,21 @@
> > > #define LINK_WAIT_MIN 90000
> > > #define LINK_WAIT_MAX 100000
> >
> > Ditto.
> >
> > > +struct mobiveil_msi { /* MSI information */
> > > + struct mutex lock; /* protect bitmap variable */
> > > + struct irq_domain *msi_domain;
> > > + struct irq_domain *dev_domain;
> > > + phys_addr_t msi_pages_phys;
> > > + int num_of_vectors;
> > > + DECLARE_BITMAP(msi_irq_in_use, PCI_NUM_MSI);
> > > +};
> > > +
> > > struct mobiveil_pcie {
> > > struct platform_device *pdev;
> > > struct list_head resources;
> > > void __iomem *config_axi_slave_base; /* endpoint config base */
> > > void __iomem *csr_axi_slave_base; /* root port config base */
> > > + void __iomem *apb_csr_base; /* MSI register base */
> > > void __iomem *pcie_reg_base; /* Physical PCIe Controller Base */
> > > struct irq_domain *intx_domain;
> > > raw_spinlock_t intx_mask_lock;
> > > @@ -115,6 +138,7 @@ struct mobiveil_pcie {
> > > int ib_wins_configured; /* configured inbound windows */
> > > struct resource *ob_io_res;
> > > char root_bus_nr;
> > > + struct mobiveil_msi msi;
> > > };
> > >
> > > static inline void csr_writel(struct mobiveil_pcie *pcie, const u32 value,
> > > @@ -194,13 +218,15 @@ static void mobiveil_pcie_isr(struct irq_desc *desc)
> > > struct irq_chip *chip = irq_desc_get_chip(desc);
> > > struct mobiveil_pcie *pcie = irq_desc_get_handler_data(desc);
> > > struct device *dev = &pcie->pdev->dev;
> > > - u32 intr_status;
> > > + struct mobiveil_msi *msi = &pcie->msi;
> > > + u32 msi_data, msi_addr_lo, msi_addr_hi;
> > > + u32 intr_status, msi_status;
> > > unsigned long shifted_status;
> > > u32 bit, virq, val, mask;
> > >
> > > /*
> > > - * The core provides interrupt for INTx.
> > > - * So we'll read INTx status.
> > > + * The core provides a single interrupt for both INTx/MSI messages.
> > > + * So we'll read both INTx and MSI status
> > > */
> > >
> > > chained_irq_enter(chip, desc);
> > > @@ -232,6 +258,39 @@ static void mobiveil_pcie_isr(struct irq_desc *desc)
> > > } while ((shifted_status >> PAB_INTX_START) != 0);
> > > }
> > >
> > > + /* read extra MSI status register */
> > > + msi_status = readl_relaxed(pcie->apb_csr_base + MSI_STATUS_OFFSET);
> > > +
> > > + /* handle MSI interrupts */
> > > + if (msi_status & 1) {
> >
> > Maybe rewriting it like this makes it clearer (and remove a level of
> > useless nesting):
> >
> > while (msi_status & 1) {
> > msi_data = readl_relaxed(pcie->apb_csr_base + MSI_DATA_OFFSET);
> >
> > /*
> > * MSI_STATUS_OFFSET register gets updated to zero
> > * once we pop not only the MSI data but also address
> > * from MSI hardware FIFO. So keeping these following
> > * two dummy reads.
> > */
> > msi_addr_lo = readl_relaxed(pcie->apb_csr_base + MSI_ADDR_L_OFFSET);
> > msi_addr_hi = readl_relaxed(pcie->apb_csr_base + MSI_ADDR_H_OFFSET);
> > dev_dbg(dev, "MSI registers, data: %08x, addr: %08x:%08x\n",
> > msi_data, msi_addr_hi, msi_addr_lo);
> >
> > virq = irq_find_mapping(msi->dev_domain, msi_data);
> > if (virq)
> > generic_handle_irq(virq);
> >
> > msi_status = readl_relaxed(pcie->apb_csr_base + MSI_STATUS_OFFSET);
> > }
> >
> OK.
>
> > > + do {
> > > + msi_data = readl_relaxed(pcie->apb_csr_base
> > > + + MSI_DATA_OFFSET);
> > > +
> > > + /*
> > > + * MSI_STATUS_OFFSET register gets updated to zero
> > > + * once we pop not only the MSI data but also address
> > > + * from MSI hardware FIFO. So keeping these following
> > > + * two dummy reads.
> > > + */
> > > + msi_addr_lo = readl_relaxed(pcie->apb_csr_base +
> > > + MSI_ADDR_L_OFFSET);
> > > + msi_addr_hi = readl_relaxed(pcie->apb_csr_base +
> > > + MSI_ADDR_H_OFFSET);
> > > + dev_dbg(dev,
> > > + "MSI registers, data: %08x, addr: %08x:%08x\n",
> > > + msi_data, msi_addr_hi, msi_addr_lo);
> > > +
> > > + virq = irq_find_mapping(msi->dev_domain,
> > > + msi_data);
> > > + if (virq)
> > > + generic_handle_irq(virq);
> > > +
> > > + msi_status = readl_relaxed(pcie->apb_csr_base +
> > > + MSI_STATUS_OFFSET);
> > > + } while (msi_status & 1);
> > > + }
> > > +
> > > /* Clear the interrupt status */
> > > csr_writel(pcie, intr_status, PAB_INTP_AMBA_MISC_STAT);
> >
> > We discussed this before, in particular the edge nature of MSIs:
> >
> > https://marc.info/?l=linux-pci&m=152214807332582&w=2
> >
> > I was wondering whether the register:
> >
> > PAB_INTP_AMBA_MISC_STAT
> >
> > has some form of ACK on the MSI interrupt so that it can be added to
> > the MSI bottom IRQ chip as required by edge IRQs. Isn't there in the
> > controller a register that works as an acknowledgement for MSIs ?
>
> It doesnt, as I have mentioned in the link you gave above,
> PCIe host hardware retires the interrupt as soon as ISR empties the
> last entry in the MSI FIFO.
> There is no special ACKing bit in any registers as such. So local
> ACKing function is not needed right ?
>
> >
> > > chained_irq_exit(chip, desc);
> > > @@ -267,6 +326,12 @@ static int mobiveil_pcie_parse_dt(struct mobiveil_pcie *pcie)
> > > return PTR_ERR(pcie->csr_axi_slave_base);
> > > pcie->pcie_reg_base = res->start;
> > >
> > > + /* map MSI config resource */
> > > + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "apb_csr");
> > > + pcie->apb_csr_base = devm_pci_remap_cfg_resource(dev, res);
> > > + if (IS_ERR(pcie->apb_csr_base))
> > > + return PTR_ERR(pcie->apb_csr_base);
> > > +
> > > /* read the number of windows requested */
> > > if (of_property_read_u32(node, "apio-wins", &pcie->apio_wins))
> > > pcie->apio_wins = MAX_PIO_WINDOWS;
> > > @@ -416,6 +481,22 @@ static int mobiveil_bringup_link(struct mobiveil_pcie *pcie)
> > > return -ETIMEDOUT;
> > > }
> > >
> > > +static void mobiveil_pcie_enable_msi(struct mobiveil_pcie *pcie)
> > > +{
> > > + phys_addr_t msg_addr = pcie->pcie_reg_base;
> > > + struct mobiveil_msi *msi = &pcie->msi;
> > > +
> > > + pcie->msi.num_of_vectors = PCI_NUM_MSI;
> > > + msi->msi_pages_phys = (phys_addr_t)msg_addr;
> > > +
> > > + writel_relaxed(lower_32_bits(msg_addr),
> > > + pcie->apb_csr_base + MSI_BASE_LO_OFFSET);
> > > + writel_relaxed(upper_32_bits(msg_addr),
> > > + pcie->apb_csr_base + MSI_BASE_HI_OFFSET);
> > > + writel_relaxed(4096, pcie->apb_csr_base + MSI_SIZE_OFFSET);
> > > + writel_relaxed(1, pcie->apb_csr_base + MSI_ENABLE_OFFSET);
> > > +}
> > > +
> > > static int mobiveil_host_init(struct mobiveil_pcie *pcie)
> > > {
> > > u32 value, pab_ctrl, type = 0;
> > > @@ -445,7 +526,7 @@ static int mobiveil_host_init(struct mobiveil_pcie *pcie)
> > > (1 << PEX_PIO_ENABLE_SHIFT),
> > > PAB_CTRL);
> > >
> > > - csr_writel(pcie, (PAB_INTP_INTX_MASK),
> > > + csr_writel(pcie, (PAB_INTP_INTX_MASK | PAB_INTP_MSI_MASK),
> > > PAB_INTP_AMBA_MISC_ENB);
> > >
> > > /*
> > > @@ -485,6 +566,9 @@ static int mobiveil_host_init(struct mobiveil_pcie *pcie)
> > > }
> > > }
> > >
> > > + /* setup MSI hardware registers */
> > > + mobiveil_pcie_enable_msi(pcie);
> > > +
> > > return err;
> > > }
> > >
> > > @@ -540,6 +624,116 @@ static int mobiveil_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
> > > .map = mobiveil_pcie_intx_map,
> > > };
> > >
> > > +static struct irq_chip mobiveil_msi_irq_chip = {
> > > + .name = "Mobiveil PCIe MSI",
> > > + .irq_mask = pci_msi_mask_irq,
> > > + .irq_unmask = pci_msi_unmask_irq,
> > > +};
> > > +
> > > +static struct msi_domain_info mobiveil_msi_domain_info = {
> > > + .flags = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> > > + MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
> > > + .chip = &mobiveil_msi_irq_chip,
> > > +};
> > > +
> > > +static void mobiveil_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> > > +{
> > > + struct mobiveil_pcie *pcie = irq_data_get_irq_chip_data(data);
> > > + phys_addr_t addr = pcie->pcie_reg_base + (data->hwirq * sizeof(int));
> > > +
> > > + msg->address_lo = lower_32_bits(addr);
> > > + msg->address_hi = upper_32_bits(addr);
> > > + msg->data = data->hwirq;
> > > +
> > > + dev_dbg(&pcie->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
> > > + (int)data->hwirq, msg->address_hi, msg->address_lo);
> > > +}
> > > +
> > > +static int mobiveil_msi_set_affinity(struct irq_data *irq_data,
> > > + const struct cpumask *mask, bool force)
> > > +{
> > > + return -EINVAL;
> > > +}
> > > +
> > > +static struct irq_chip mobiveil_msi_bottom_irq_chip = {
> > > + .name = "Mobiveil MSI",
> > > + .irq_compose_msi_msg = mobiveil_compose_msi_msg,
> > > + .irq_set_affinity = mobiveil_msi_set_affinity,
> > > +};
> > > +
> > > +static int mobiveil_irq_msi_domain_alloc(struct irq_domain *domain,
> > > + unsigned int virq, unsigned int nr_irqs, void *args)
> > > +{
> > > + struct mobiveil_pcie *pcie = domain->host_data;
> > > + struct mobiveil_msi *msi = &pcie->msi;
> > > + unsigned long bit;
> > > +
> > > + WARN_ON(nr_irqs != 1);
> > > + mutex_lock(&msi->lock);
> > > +
> > > + bit = find_first_zero_bit(msi->msi_irq_in_use, msi->num_of_vectors);
> > > + if (bit >= msi->num_of_vectors) {
> > > + mutex_unlock(&msi->lock);
> > > + return -ENOSPC;
> > > + }
> > > +
> > > + set_bit(bit, msi->msi_irq_in_use);
> > > +
> > > + mutex_unlock(&msi->lock);
> > > +
> > > + irq_domain_set_info(domain, virq, bit, &mobiveil_msi_bottom_irq_chip,
> > > + domain->host_data, handle_level_irq,
> >
> > The flow handler should be handle_edge_irq and
>
>
> Below is the discussion from the above linked marc.info link about edge handler:
>
> >>>> You need handle_edge_irq() here as a flow handler.
> >>>>
> >>> in our hardware case, INTX and MSI interrupts are provided to the
> >>> processor core as a level interrupt, tested with handle_level_irq()
> >>> successfully, as expected handle_edge_irq() crashes.
> >>
> >> This hardly makes any sense. An MSI is a write from a device to the MSI
> >> controller. There is no extra write to indicate that the interrupt has
> >> been retired. So how can that be a level interrupt?
> >>
> >
> > PCIe host hardware retires the interrupt as soon as ISR empties the
> > last entry in the MSI FIFO.
>
> And that interrupt is *not* an MSI.
>
> >
> >> You say that handle_edge_irq() crashes. How?
> >>
> > panics with following crash log:
> > [ 107.358756] [00000000] *pgd=0000000b7fffe003[ 107.363004] ,
> > *pud=0000000b7fffe003
> > , *pmd=0000000000000000[ 107.368470]
> > [ 107.369954] Internal error: Oops: 86000005 [#1] SMP
> > [ 107.374815] Modules linked in: r8169 pcie_mobiveil(O) uio_pdrv_genirq
> > [ 107.381239] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W O
> > 4.9.0-xilinx-v2017.2 #1
> > [ 107.389577] Hardware name: xlnx,zynqmp (DT)
> > [ 107.393737] task: ffffff8008c90880 task.stack: ffffff8008c80000
> > [ 107.399642] PC is at 0x0
> > [ 107.402162] LR is at handle_edge_irq+0x104/0x1a8
>
> Well, you're obviously missing an irqchip callback here. Debug time.
>
> So my question is, it looks like kernel is also considering it as
> level interrupt and handling it, as
> our HW is interrupting the CPU with a level triggered.
>
> also other than tango and hyperv all others seems to be using either
> simple or level handlers for MSI handling.
That does not mean that they should.
> pcie-designware-host.c: handle_simple_irq
> pci-aardvark.c: handle_level_irq
> pci-tegra.c: handle_simple_irq
> pcie-mediatek.c : handle_simple_irq
> pcie-rcar.c: handle_simple_irq
> pcie-xilinx.c: handle_simple_irq
>
> so isnt it because they also have similar hardware implementations? so
> can we continue with handle_level_irq for this driver ?
Some of them ACK the MSI in the IRQ action - so you should not look
into those since they are bad examples.
As for your code, I will take it, yes, as an exception (whether the code
actually works that's an answer I can't have so I take it to make
forward progress).
Before re-posting please go through all the formatting comments
(tabs, multiple lines that are not needed, etc.) on all the patches,
I already commented on most of them, it should not be that complicated
to fix them up.
Thanks,
Lorenzo
