Re: [PATCH v1 5/9] PCI: microchip: Gather MSI information from hardware config registers

Conor Dooley
2022-11-23T22:11:37Z

On Wed, Nov 16, 2022 at 01:55:00PM +0000, daire.mcnamara@microchip.com wrote:
> From: Daire McNamara <daire.mcnamara@microchip.com>
>
> The PCIe root complex on PolarFire SoC is configured at bitstream creation
> time using Libero. Key MSI-related parameters include the number of
> MSIs (1/2/4/8/16/32) and the MSI address. In the device driver, extract
> this information from hw registers at init time, and use it to configure

I don't know the answer here, so I am not being difficult:
Does the HSS program them in based on the XML produced alongside the
bitstream, or is that information encoded in the bitstream itself?

> MSI system, including configuring MSI capability structure correctly in
> configuration space.
>
> Signed-off-by: Daire McNamara <daire.mcnamara@microchip.com>
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
> drivers/pci/controller/pcie-microchip-host.c | 73 +++++++++++---------
> 1 file changed, 40 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-microchip-host.c b/drivers/pci/controller/pcie-microchip-host.c
> index ecd4d3f3e3d4..faecf419ad6f 100644
> --- a/drivers/pci/controller/pcie-microchip-host.c
> +++ b/drivers/pci/controller/pcie-microchip-host.c
> @@ -20,8 +20,7 @@
> #include "../pci.h"
>
> /* Number of MSI IRQs */
> -#define MC_NUM_MSI_IRQS 32
> -#define MC_NUM_MSI_IRQS_CODED 5
> +#define MC_MAX_NUM_MSI_IRQS 32
>
> /* PCIe Bridge Phy and Controller Phy offsets */
> #define MC_PCIE1_BRIDGE_ADDR 0x00008000u
> @@ -31,6 +30,11 @@
> #define MC_PCIE_CTRL_ADDR (MC_PCIE1_CTRL_ADDR)
>
> /* PCIe Bridge Phy Regs */
> +#define PCIE_PCI_IRQ_DW0 0xa8
> +#define MSIX_CAP_MASK BIT(31)
> +#define NUM_MSI_MSGS_MASK GENMASK(6, 4)
> +#define NUM_MSI_MSGS_SHIFT 4
> +
> #define IMASK_LOCAL 0x180
> #define DMA_END_ENGINE_0_MASK 0x00000000u
> #define DMA_END_ENGINE_0_SHIFT 0
> @@ -79,7 +83,6 @@
> #define IMASK_HOST 0x188
> #define ISTATUS_HOST 0x18c
> #define IMSI_ADDR 0x190
> -#define MSI_ADDR 0x190
> #define ISTATUS_MSI 0x194
>
> /* PCIe Master table init defines */
> @@ -156,8 +159,6 @@
>
> /* PCIe Config space MSI capability structure */
> #define MC_MSI_CAP_CTRL_OFFSET 0xe0u
> -#define MC_MSI_MAX_Q_AVAIL (MC_NUM_MSI_IRQS_CODED << 1)
> -#define MC_MSI_Q_SIZE (MC_NUM_MSI_IRQS_CODED << 4)
>
> /* Events */
> #define EVENT_PCIE_L2_EXIT 0
> @@ -257,7 +258,7 @@ struct mc_msi {
> struct irq_domain *dev_domain;
> u32 num_vectors;
> u64 vector_phy;
> - DECLARE_BITMAP(used, MC_NUM_MSI_IRQS);
> + DECLARE_BITMAP(used, MC_MAX_NUM_MSI_IRQS);
> };
>
> struct mc_pcie {
> @@ -380,25 +381,29 @@ static struct {
>
> static char poss_clks[][5] = { "fic0", "fic1", "fic2", "fic3" };
>
> -static void mc_pcie_enable_msi(struct mc_pcie *port, void __iomem *base)
> +static void mc_pcie_fixup_ecam(struct mc_pcie *port, void __iomem *ecam)
> {
> struct mc_msi *msi = &port->msi;
> - u32 cap_offset = MC_MSI_CAP_CTRL_OFFSET;
> - u16 msg_ctrl = readw_relaxed(base + cap_offset + PCI_MSI_FLAGS);
> -
> - msg_ctrl |= PCI_MSI_FLAGS_ENABLE;
> - msg_ctrl &= ~PCI_MSI_FLAGS_QMASK;
> - msg_ctrl |= MC_MSI_MAX_Q_AVAIL;
> - msg_ctrl &= ~PCI_MSI_FLAGS_QSIZE;
> - msg_ctrl |= MC_MSI_Q_SIZE;
> - msg_ctrl |= PCI_MSI_FLAGS_64BIT;
> -
> - writew_relaxed(msg_ctrl, base + cap_offset + PCI_MSI_FLAGS);
> -
> + u16 reg;
> + u8 queue_size;
> +
> + /* fixup msi enable flag */
> + reg = readw_relaxed(ecam + MC_MSI_CAP_CTRL_OFFSET + PCI_MSI_FLAGS);
> + reg |= PCI_MSI_FLAGS_ENABLE;
> + writew_relaxed(reg, ecam + MC_MSI_CAP_CTRL_OFFSET + PCI_MSI_FLAGS);
> +
> + /* fixup msi queue flags */
> + queue_size = reg & PCI_MSI_FLAGS_QMASK;
> + queue_size >>= 1;
> + reg &= ~PCI_MSI_FLAGS_QSIZE;
> + reg |= queue_size << 4;

Could you please explain where the >> 1 & << 4 come from? Maybe it's
sufficient to just make them defines, or the comment here could be
expanded on.

> + writew_relaxed(reg, ecam + MC_MSI_CAP_CTRL_OFFSET + PCI_MSI_FLAGS);
> +
> + /* fixup msi addr fields */
> writel_relaxed(lower_32_bits(msi->vector_phy),
> - base + cap_offset + PCI_MSI_ADDRESS_LO);
> + ecam + MC_MSI_CAP_CTRL_OFFSET + PCI_MSI_ADDRESS_LO);
> writel_relaxed(upper_32_bits(msi->vector_phy),
> - base + cap_offset + PCI_MSI_ADDRESS_HI);
> + ecam + MC_MSI_CAP_CTRL_OFFSET + PCI_MSI_ADDRESS_HI);
> }
>
> static void mc_handle_msi(struct irq_desc *desc)
> @@ -471,10 +476,7 @@ static int mc_irq_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
> {
> struct mc_pcie *port = domain->host_data;
> struct mc_msi *msi = &port->msi;
> - void __iomem *bridge_base_addr =
> - port->axi_base_addr + MC_PCIE_BRIDGE_ADDR;
> unsigned long bit;
> - u32 val;
>
> mutex_lock(&msi->lock);
> bit = find_first_zero_bit(msi->used, msi->num_vectors);
> @@ -488,11 +490,6 @@ static int mc_irq_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
> irq_domain_set_info(domain, virq, bit, &mc_msi_bottom_irq_chip,
> domain->host_data, handle_edge_irq, NULL, NULL);
>
> - /* Enable MSI interrupts */
> - val = readl_relaxed(bridge_base_addr + IMASK_LOCAL);
> - val |= PM_MSI_INT_MSI_MASK;
> - writel_relaxed(val, bridge_base_addr + IMASK_LOCAL);
> -
> mutex_unlock(&msi->lock);
>
> return 0;
> @@ -1102,6 +1099,7 @@ static int mc_platform_init(struct pci_config_window *cfg)
> void __iomem *bridge_base_addr;
> void __iomem *ctrl_base_addr;
> int ret;
> + u32 val;
>
> port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> if (!port)
> @@ -1123,11 +1121,20 @@ static int mc_platform_init(struct pci_config_window *cfg)
> bridge_base_addr = port->axi_base_addr + MC_PCIE_BRIDGE_ADDR;
> ctrl_base_addr = port->axi_base_addr + MC_PCIE_CTRL_ADDR;
>
> - port->msi.vector_phy = MSI_ADDR;
> - port->msi.num_vectors = MC_NUM_MSI_IRQS;
> + /* allow enabling msi by disabling msi-x */
> + val = readl(bridge_base_addr + PCIE_PCI_IRQ_DW0);
> + val &= ~MSIX_CAP_MASK;
> + writel(val, bridge_base_addr + PCIE_PCI_IRQ_DW0);
> +
> + /* pick num vectors from design */
> + val = readl(bridge_base_addr + PCIE_PCI_IRQ_DW0);
> + val &= NUM_MSI_MSGS_MASK;
> + val >>= NUM_MSI_MSGS_SHIFT;
> +
> + port->msi.num_vectors = 1 << val;
>
> - /* Hardware doesn't setup MSI by default */
> - mc_pcie_enable_msi(port, cfg->win);
> + /* pick vector address from design */

"Design" might make sense to you or I, but I think you could expand this
comment for the lay reader. Copy-paste from the commit message maybe
hah.

Anyways, as with the rest of the series - I'm just nitpicking.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

> + port->msi.vector_phy = readl_relaxed(bridge_base_addr + IMSI_ADDR);
>
> /* Configure Address Translation Table 0 for PCIe config space */
> mc_pcie_setup_window(bridge_base_addr, 0, cfg->res.start & 0xffffffff,
> --
> 2.25.1
>
>
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