Re: [PATCH v1 7/8] PCI: microchip: Gather MSI information from hardware config registers

[Lorenzo Pieralisi <lpieralisi@kernel.org>]

On Wed, Jun 14, 2023 at 04:55:55PM +0100, 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
> MSI system, including configuring MSI capability structure correctly in
> configuration space.
> 
> Signed-off-by: Daire McNamara <daire.mcnamara@microchip.com>
> Reviewed-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 751f0243deb4..9ff0fb04b953 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 */
> @@ -158,8 +161,6 @@
>  
>  /* 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
> @@ -259,7 +260,7 @@ 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 {
> @@ -382,25 +383,29 @@ 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 PCI MSI queue flags */
> +	queue_size = reg & PCI_MSI_FLAGS_QMASK;
> +	queue_size >>= 1;
> +	reg &= ~PCI_MSI_FLAGS_QSIZE;
> +	reg |= queue_size << 4;
> +	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);

This hunk is just code refactoring that has nothing to do AFAICS with
the commit log purpose, a patch must have a single logical purpose.

>  }
>  
>  static void mc_handle_msi(struct irq_desc *desc)
> @@ -473,10 +478,7 @@ 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);
> @@ -490,11 +492,6 @@ 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;
> @@ -1117,6 +1114,7 @@ static int mc_platform_init(struct pci_config_window *cfg)
>  	struct mc_pcie *port;
>  	void __iomem *bridge_base_addr;
>  	int ret;
> +	u32 val;
>  
>  	port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
>  	if (!port)
> @@ -1137,11 +1135,20 @@ static int mc_platform_init(struct pci_config_window *cfg)
>  
>  	bridge_base_addr = port->axi_base_addr + MC_PCIE_BRIDGE_ADDR;
>  
> -	port->msi.vector_phy = MSI_ADDR;
> -	port->msi.num_vectors = MC_NUM_MSI_IRQS;
> +	/* Allow enabling MSI by disabling MSI-X */

Mmm..see above. It is not clear to me what this patch does overall, for
certain it does more that what's stated in the commit log and this ought
to be fixed.

Lorenzo

> +	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 bitfile programmed onto FPGA fabric */
> +	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 */
> +	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
>