Re: [PATCH v4 6/7] PCI: dwc: al: Add support for DW based driver type

Andrew Murray
2019-08-22T10:00:43Z

On Wed, Aug 21, 2019 at 06:47:44PM +0300, Jonathan Chocron wrote:
> This driver is DT based and utilizes the DesignWare APIs.
>
> It allows using a smaller ECAM range for a larger bus range -
> usually an entire bus uses 1MB of address space, but the driver
> can use it for a larger number of buses. This is achieved by using a HW
> mechanism which allows changing the BUS part of the "final" outgoing
> config transaction. There are 2 HW regs, one which is basically a
> bitmask determining which bits to take from the AXI transaction itself
> and another which holds the complementary part programmed by the
> driver.
>
> All link initializations are handled by the boot FW.
>
> Signed-off-by: Jonathan Chocron <jonnyc@amazon.com>
> Reviewed-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> ---
> drivers/pci/controller/dwc/Kconfig | 12 +
> drivers/pci/controller/dwc/pcie-al.c | 365 +++++++++++++++++++++++++++
> 2 files changed, 377 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> index 6ea778ae4877..3c6094cbcc3b 100644
> --- a/drivers/pci/controller/dwc/Kconfig
> +++ b/drivers/pci/controller/dwc/Kconfig
> @@ -230,4 +230,16 @@ config PCIE_UNIPHIER
> Say Y here if you want PCIe controller support on UniPhier SoCs.
> This driver supports LD20 and PXs3 SoCs.
>
> +config PCIE_AL
> + bool "Amazon Annapurna Labs PCIe controller"
> + depends on OF && (ARM64 || COMPILE_TEST)
> + depends on PCI_MSI_IRQ_DOMAIN
> + select PCIE_DW_HOST
> + help
> + Say Y here to enable support of the Amazon's Annapurna Labs PCIe
> + controller IP on Amazon SoCs. The PCIe controller uses the DesignWare
> + core plus Annapurna Labs proprietary hardware wrappers. This is
> + required only for DT-based platforms. ACPI platforms with the
> + Annapurna Labs PCIe controller don't need to enable this.
> +
> endmenu
> diff --git a/drivers/pci/controller/dwc/pcie-al.c b/drivers/pci/controller/dwc/pcie-al.c
> index 3ab58f0584a8..1eeda2f6371f 100644
> --- a/drivers/pci/controller/dwc/pcie-al.c
> +++ b/drivers/pci/controller/dwc/pcie-al.c
> @@ -91,3 +91,368 @@ struct pci_ecam_ops al_pcie_ops = {
> };
>
> #endif /* defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS) */
> +
> +#ifdef CONFIG_PCIE_AL
> +
> +#include <linux/of_pci.h>
> +#include "pcie-designware.h"
> +
> +#define AL_PCIE_REV_ID_2 2
> +#define AL_PCIE_REV_ID_3 3
> +#define AL_PCIE_REV_ID_4 4
> +
> +#define AXI_BASE_OFFSET 0x0

Is this really needed? It cleanly describes how the hardware is composed but
given that it's 0 and will always be 0, it seems to add some bloat.

> +
> +#define DEVICE_ID_OFFSET 0x16c
> +
> +#define DEVICE_REV_ID 0x0
> +#define DEVICE_REV_ID_DEV_ID_MASK GENMASK(31, 16)
> +
> +#define DEVICE_REV_ID_DEV_ID_X4 0
> +#define DEVICE_REV_ID_DEV_ID_X8 2
> +#define DEVICE_REV_ID_DEV_ID_X16 4
> +
> +#define OB_CTRL_REV1_2_OFFSET 0x0040
> +#define OB_CTRL_REV3_5_OFFSET 0x0030
> +
> +#define CFG_TARGET_BUS 0x0
> +#define CFG_TARGET_BUS_MASK_MASK GENMASK(7, 0)
> +#define CFG_TARGET_BUS_BUSNUM_MASK GENMASK(15, 8)
> +
> +#define CFG_CONTROL 0x4
> +#define CFG_CONTROL_SUBBUS_MASK GENMASK(15, 8)
> +#define CFG_CONTROL_SEC_BUS_MASK GENMASK(23, 16)
> +
> +struct al_pcie_reg_offsets {
> + unsigned int ob_ctrl;
> +};
> +
> +struct al_pcie_target_bus_cfg {
> + u8 reg_val;
> + u8 reg_mask;
> + u8 ecam_mask;
> +};
> +
> +struct al_pcie {
> + struct dw_pcie *pci;
> + void __iomem *controller_base; /* base of PCIe unit (not DW core) */
> + struct device *dev;
> + resource_size_t ecam_size;
> + unsigned int controller_rev_id;
> + struct al_pcie_reg_offsets reg_offsets;
> + struct al_pcie_target_bus_cfg target_bus_cfg;
> +};
> +
> +#define PCIE_ECAM_DEVFN(x) (((x) & 0xff) << 12)
> +
> +#define to_al_pcie(x) dev_get_drvdata((x)->dev)
> +
> +static inline u32 al_pcie_controller_readl(struct al_pcie *pcie, u32 offset)
> +{
> + return readl_relaxed(pcie->controller_base + offset);
> +}
> +
> +static inline void al_pcie_controller_writel(struct al_pcie *pcie, u32 offset,
> + u32 val)
> +{
> + writel_relaxed(val, pcie->controller_base + offset);
> +}
> +
> +static int al_pcie_rev_id_get(struct al_pcie *pcie, unsigned int *rev_id)
> +{
> + u32 dev_rev_id_val;
> + u32 dev_id_val;
> +
> + dev_rev_id_val = al_pcie_controller_readl(pcie, AXI_BASE_OFFSET +
> + DEVICE_ID_OFFSET +
> + DEVICE_REV_ID);
> + dev_id_val = FIELD_GET(DEVICE_REV_ID_DEV_ID_MASK, dev_rev_id_val);
> +
> + switch (dev_id_val) {
> + case DEVICE_REV_ID_DEV_ID_X4:
> + *rev_id = AL_PCIE_REV_ID_2;
> + break;
> + case DEVICE_REV_ID_DEV_ID_X8:
> + *rev_id = AL_PCIE_REV_ID_3;
> + break;
> + case DEVICE_REV_ID_DEV_ID_X16:
> + *rev_id = AL_PCIE_REV_ID_4;
> + break;
> + default:
> + dev_err(pcie->dev, "Unsupported dev_id_val (0x%x)\n",
> + dev_id_val);
> + return -EINVAL;
> + }
> +
> + dev_dbg(pcie->dev, "dev_id_val: 0x%x\n", dev_id_val);
> +
> + return 0;
> +}
> +
> +static int al_pcie_reg_offsets_set(struct al_pcie *pcie)
> +{
> + switch (pcie->controller_rev_id) {
> + case AL_PCIE_REV_ID_2:
> + pcie->reg_offsets.ob_ctrl = OB_CTRL_REV1_2_OFFSET;
> + break;
> + case AL_PCIE_REV_ID_3:
> + case AL_PCIE_REV_ID_4:
> + pcie->reg_offsets.ob_ctrl = OB_CTRL_REV3_5_OFFSET;
> + break;
> + default:
> + dev_err(pcie->dev, "Unsupported controller rev_id: 0x%x\n",
> + pcie->controller_rev_id);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static inline void al_pcie_target_bus_set(struct al_pcie *pcie,
> + u8 target_bus,
> + u8 mask_target_bus)
> +{
> + u32 reg;
> +
> + reg = FIELD_PREP(CFG_TARGET_BUS_MASK_MASK, mask_target_bus) |
> + FIELD_PREP(CFG_TARGET_BUS_BUSNUM_MASK, target_bus);
> +
> + al_pcie_controller_writel(pcie, AXI_BASE_OFFSET +
> + pcie->reg_offsets.ob_ctrl + CFG_TARGET_BUS,
> + reg);
> +}
> +
> +static void __iomem *al_pcie_conf_addr_map(struct al_pcie *pcie,
> + unsigned int busnr,
> + unsigned int devfn)
> +{
> + struct al_pcie_target_bus_cfg *target_bus_cfg = &pcie->target_bus_cfg;
> + unsigned int busnr_ecam = busnr & target_bus_cfg->ecam_mask;
> + unsigned int busnr_reg = busnr & target_bus_cfg->reg_mask;
> + struct pcie_port *pp = &pcie->pci->pp;
> + void __iomem *pci_base_addr;
> +
> + pci_base_addr = (void __iomem *)((uintptr_t)pp->va_cfg0_base +
> + (busnr_ecam << 20) +
> + PCIE_ECAM_DEVFN(devfn));
> +
> + if (busnr_reg != target_bus_cfg->reg_val) {
> + dev_dbg(pcie->pci->dev, "Changing target bus busnum val from 0x%x to 0x%x\n",
> + target_bus_cfg->reg_val, busnr_reg);
> + target_bus_cfg->reg_val = busnr_reg;
> + al_pcie_target_bus_set(pcie,
> + target_bus_cfg->reg_val,
> + target_bus_cfg->reg_mask);
> + }
> +
> + return pci_base_addr;
> +}
> +
> +static int al_pcie_rd_other_conf(struct pcie_port *pp, struct pci_bus *bus,
> + unsigned int devfn, int where, int size,
> + u32 *val)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> + struct al_pcie *pcie = to_al_pcie(pci);
> + unsigned int busnr = bus->number;
> + void __iomem *pci_addr;
> + int rc;
> +
> + pci_addr = al_pcie_conf_addr_map(pcie, busnr, devfn);
> +
> + rc = dw_pcie_read(pci_addr + where, size, val);
> +
> + dev_dbg(pci->dev, "%d-byte config read from %04x:%02x:%02x.%d offset 0x%x (pci_addr: 0x%px) - val:0x%x\n",
> + size, pci_domain_nr(bus), bus->number,
> + PCI_SLOT(devfn), PCI_FUNC(devfn), where,
> + (pci_addr + where), *val);
> +
> + return rc;
> +}
> +
> +static int al_pcie_wr_other_conf(struct pcie_port *pp, struct pci_bus *bus,
> + unsigned int devfn, int where, int size,
> + u32 val)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> + struct al_pcie *pcie = to_al_pcie(pci);
> + unsigned int busnr = bus->number;
> + void __iomem *pci_addr;
> + int rc;
> +
> + pci_addr = al_pcie_conf_addr_map(pcie, busnr, devfn);
> +
> + rc = dw_pcie_write(pci_addr + where, size, val);
> +
> + dev_dbg(pci->dev, "%d-byte config write to %04x:%02x:%02x.%d offset 0x%x (pci_addr: 0x%px) - val:0x%x\n",
> + size, pci_domain_nr(bus), bus->number,
> + PCI_SLOT(devfn), PCI_FUNC(devfn), where,
> + (pci_addr + where), val);
> +
> + return rc;
> +}
> +
> +static void al_pcie_config_prepare(struct al_pcie *pcie)
> +{
> + struct al_pcie_target_bus_cfg *target_bus_cfg;
> + struct pcie_port *pp = &pcie->pci->pp;
> + unsigned int ecam_bus_mask;
> + u32 cfg_control_offset;
> + u8 subordinate_bus;
> + u8 secondary_bus;
> + u32 cfg_control;
> + u32 reg;
> +
> + target_bus_cfg = &pcie->target_bus_cfg;
> +
> + ecam_bus_mask = (pcie->ecam_size >> 20) - 1;
> + if (ecam_bus_mask > 255) {
> + dev_warn(pcie->dev, "ECAM window size is larger than 256MB. Cutting off at 256\n");
> + ecam_bus_mask = 255;
> + }
> +
> + /* This portion is taken from the transaction address */
> + target_bus_cfg->ecam_mask = ecam_bus_mask;
> + /* This portion is taken from the cfg_target_bus reg */
> + target_bus_cfg->reg_mask = ~target_bus_cfg->ecam_mask;
> + target_bus_cfg->reg_val = pp->busn->start & target_bus_cfg->reg_mask;

If I understand correctly - there is an optimisation in al_pcie_conf_addr_map
that prevents an unnecessary write to the controller if it's already programmed
to the bus we want to talk to. Due to this optimisation we need to ensure the
default values in target_bus_cfg match what the hardware is initially programmed
to. So to be on the safe side we program them at the start of day.

It sounds like the controller isn't reset anywhere post-firmware? so we have
no idea what value the hardware may be programmed to?

> +
> + al_pcie_target_bus_set(pcie, target_bus_cfg->reg_val,
> + target_bus_cfg->reg_mask);
> +
> + secondary_bus = pp->busn->start + 1;
> + subordinate_bus = pp->busn->end;
> +
> + /* Set the valid values of secondary and subordinate buses */
> + cfg_control_offset = AXI_BASE_OFFSET + pcie->reg_offsets.ob_ctrl +
> + CFG_CONTROL;
> +
> + cfg_control = al_pcie_controller_readl(pcie, cfg_control_offset);
> +
> + reg = cfg_control &
> + ~(CFG_CONTROL_SEC_BUS_MASK | CFG_CONTROL_SUBBUS_MASK);
> +
> + reg |= FIELD_PREP(CFG_CONTROL_SUBBUS_MASK, subordinate_bus) |
> + FIELD_PREP(CFG_CONTROL_SEC_BUS_MASK, secondary_bus);
> +
> + al_pcie_controller_writel(pcie, cfg_control_offset, reg);
> +}
> +
> +static int al_pcie_host_init(struct pcie_port *pp)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> + struct al_pcie *pcie = to_al_pcie(pci);
> + int rc;
> +
> + rc = al_pcie_rev_id_get(pcie, &pcie->controller_rev_id);
> + if (rc)
> + return rc;
> +
> + rc = al_pcie_reg_offsets_set(pcie);
> + if (rc)
> + return rc;
> +
> + al_pcie_config_prepare(pcie);
> +
> + return 0;
> +}
> +
> +static const struct dw_pcie_host_ops al_pcie_host_ops = {
> + .rd_other_conf = al_pcie_rd_other_conf,
> + .wr_other_conf = al_pcie_wr_other_conf,
> + .host_init = al_pcie_host_init,
> +};
> +
> +static int al_add_pcie_port(struct pcie_port *pp,
> + struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + int ret;
> +
> + pp->ops = &al_pcie_host_ops;
> +
> + ret = dw_pcie_host_init(pp);
> + if (ret) {
> + dev_err(dev, "failed to initialize host\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> +};
> +
> +static int al_pcie_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct resource *controller_res;
> + struct resource *ecam_res;
> + struct resource *dbi_res;
> + struct al_pcie *al_pcie;
> + struct dw_pcie *pci;
> +
> + al_pcie = devm_kzalloc(dev, sizeof(*al_pcie), GFP_KERNEL);
> + if (!al_pcie)
> + return -ENOMEM;
> +
> + pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
> + if (!pci)
> + return -ENOMEM;
> +
> + pci->dev = dev;
> + pci->ops = &dw_pcie_ops;
> +
> + al_pcie->pci = pci;
> + al_pcie->dev = dev;
> +
> + dbi_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dbi");
> + pci->dbi_base = devm_pci_remap_cfg_resource(dev, dbi_res);
> + if (IS_ERR(pci->dbi_base)) {
> + dev_err(dev, "couldn't remap dbi base %pR\n", dbi_res);
> + return PTR_ERR(pci->dbi_base);
> + }
> +
> + ecam_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config");
> + if (!ecam_res) {
> + dev_err(dev, "couldn't find 'config' reg in DT\n");
> + return -ENOENT;
> + }
> + al_pcie->ecam_size = resource_size(ecam_res);

Instead of getting the ecam_size from the device tree here, you could just use
al_pcie->pci->pp.cfg0_size instead. I.e. in al_pcie_config_prepare...

ecam_bus_mask = (pcie->pci->pp.cfg0_size >> 19) - 1;

Though you could argue that accessing something private to the dwc host driver
unnecessarily increases the coupling between the two and makes the AL driver
more fragile. But just an observation I thought I'd point out.

Even without any more changes to this patch:

Reviewed-by: Andrew Murray <andrew.murray@arm.com>

> +
> + controller_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> + "controller");
> + al_pcie->controller_base = devm_ioremap_resource(dev, controller_res);
> + if (IS_ERR(al_pcie->controller_base)) {
> + dev_err(dev, "couldn't remap controller base %pR\n",
> + controller_res);
> + return PTR_ERR(al_pcie->controller_base);
> + }
> +
> + dev_dbg(dev, "From DT: dbi_base: %pR, controller_base: %pR\n",
> + dbi_res, controller_res);
> +
> + platform_set_drvdata(pdev, al_pcie);
> +
> + return al_add_pcie_port(&pci->pp, pdev);
> +}
> +
> +static const struct of_device_id al_pcie_of_match[] = {
> + { .compatible = "amazon,al-alpine-v2-pcie",
> + },
> + { .compatible = "amazon,al-alpine-v3-pcie",
> + },
> + {},
> +};
> +
> +static struct platform_driver al_pcie_driver = {
> + .driver = {
> + .name = "al-pcie",
> + .of_match_table = al_pcie_of_match,
> + .suppress_bind_attrs = true,
> + },
> + .probe = al_pcie_probe,
> +};
> +builtin_platform_driver(al_pcie_driver);
> +
> +#endif /* CONFIG_PCIE_AL*/
> --
> 2.17.1
>