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PCI: keystone: Add support to build as a loadable module

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The 'pci-keystone.c' driver is the application/glue/wrapper driver for the
Designware PCIe Controllers on TI SoCs. Now that all of the helper APIs
that the 'pci-keystone.c' driver depends upon have been exported for use,
enable support to build the driver as a loadable module.

When building the driver as a module, the functions marked by the '__init'
keyword may be invoked after the init memory has been freed by the kernel.
This results will result in an exception of the form:

  Unable to handle kernel paging request at virtual address ...
  Mem abort info:
  ...
  pc : ks_pcie_host_init+0x0/0x540
  lr : dw_pcie_host_init+0x170/0x498
  ...
  ks_pcie_host_init+0x0/0x540 (P)
  ks_pcie_probe+0x728/0x84c
  platform_probe+0x5c/0x98
  really_probe+0xbc/0x29c
  __driver_probe_device+0x78/0x12c
  driver_probe_device+0xd8/0x15c

To address this, introduce a new function namely 'ks_pcie_init()' to
register the 'fault handler' while removing the '__init' keyword from
existing functions.

Note that hook_fault_code() is defined as '__init' function. Since the init
functions should never be called during runtime (after init memory freeing
stage), the driver is made as a built-in if CONFIG_ARM (where
hook_fault_code() is used) is selected.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
[mani: added a note about hook_fault_code()]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20251029080547.1253757-5-s-vadapalli@ti.com
This commit is contained in:
Siddharth Vadapalli 2025-10-29 13:34:52 +05:30 committed by Bjorn Helgaas
parent 5aa84c034a
commit bc10d0ad54
3 changed files with 59 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
drivers/pci/controller/dwc/Kconfig
View File

@ -482,15 +482,21 @@ config PCI_DRA7XX_EP
to enable device-specific features PCI_DRA7XX_EP must be selected.
This uses the DesignWare core.
# ARM32 platforms use hook_fault_code() and cannot support loadable module.
config PCI_KEYSTONE
bool
# On non-ARM32 platforms, loadable module can be supported.
config PCI_KEYSTONE_TRISTATE
tristate
config PCI_KEYSTONE_HOST
bool "TI Keystone PCIe controller (host mode)"
tristate "TI Keystone PCIe controller (host mode)"
depends on ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
depends on PCI_MSI
select PCIE_DW_HOST
select PCI_KEYSTONE
select PCI_KEYSTONE if ARM
select PCI_KEYSTONE_TRISTATE if !ARM
help
Enables support for the PCIe controller in the Keystone SoC to
work in host mode. The PCI controller on Keystone is based on
@ -498,11 +504,12 @@ config PCI_KEYSTONE_HOST
DesignWare core functions to implement the driver.
config PCI_KEYSTONE_EP
bool "TI Keystone PCIe controller (endpoint mode)"
tristate "TI Keystone PCIe controller (endpoint mode)"
depends on ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
depends on PCI_ENDPOINT
select PCIE_DW_EP
select PCI_KEYSTONE
select PCI_KEYSTONE if ARM
select PCI_KEYSTONE_TRISTATE if !ARM
help
Enables support for the PCIe controller in the Keystone SoC to
work in endpoint mode. The PCI controller on Keystone is based

3
drivers/pci/controller/dwc/Makefile
View File

@ -11,7 +11,10 @@ obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
obj-$(CONFIG_PCIE_FU740) += pcie-fu740.o
obj-$(CONFIG_PCI_IMX6) += pci-imx6.o
obj-$(CONFIG_PCIE_SPEAR13XX) += pcie-spear13xx.o
# ARM32 platforms use hook_fault_code() and cannot support loadable module.
obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone.o
# On non-ARM32 platforms, loadable module can be supported.
obj-$(CONFIG_PCI_KEYSTONE_TRISTATE) += pci-keystone.o
obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
obj-$(CONFIG_PCI_LAYERSCAPE_EP) += pci-layerscape-ep.o
obj-$(CONFIG_PCIE_QCOM_COMMON) += pcie-qcom-common.o

78
drivers/pci/controller/dwc/pci-keystone.c
View File

@ -17,6 +17,7 @@
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/msi.h>
#include <linux/of.h>
#include <linux/of_irq.h>
@ -777,29 +778,7 @@ static int ks_pcie_config_intx_irq(struct keystone_pcie *ks_pcie)
return ret;
}
#ifdef CONFIG_ARM
/*
* When a PCI device does not exist during config cycles, keystone host
* gets a bus error instead of returning 0xffffffff (PCI_ERROR_RESPONSE).
* This handler always returns 0 for this kind of fault.
*/
static int ks_pcie_fault(unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
{
unsigned long instr = *(unsigned long *) instruction_pointer(regs);
if ((instr & 0x0e100090) == 0x00100090) {
int reg = (instr >> 12) & 15;
regs->uregs[reg] = -1;
regs->ARM_pc += 4;
}
return 0;
}
#endif
static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
static int ks_pcie_init_id(struct keystone_pcie *ks_pcie)
{
int ret;
unsigned int id;
@ -831,7 +810,7 @@ static int __init ks_pcie_init_id(struct keystone_pcie *ks_pcie)
return 0;
}
static int __init ks_pcie_host_init(struct dw_pcie_rp *pp)
static int ks_pcie_host_init(struct dw_pcie_rp *pp)
{
struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
struct keystone_pcie *ks_pcie = to_keystone_pcie(pci);
@ -861,15 +840,6 @@ static int __init ks_pcie_host_init(struct dw_pcie_rp *pp)
if (ret < 0)
return ret;
#ifdef CONFIG_ARM
/*
* PCIe access errors that result into OCP errors are caught by ARM as
* "External aborts"
*/
hook_fault_code(17, ks_pcie_fault, SIGBUS, 0,
"Asynchronous external abort");
#endif
return 0;
}
@ -1134,6 +1104,7 @@ static const struct of_device_id ks_pcie_of_match[] = {
},
{ },
};
MODULE_DEVICE_TABLE(of, ks_pcie_of_match);
static int ks_pcie_probe(struct platform_device *pdev)
{
@ -1381,4 +1352,45 @@ static struct platform_driver ks_pcie_driver = {
.of_match_table = ks_pcie_of_match,
},
};
#ifdef CONFIG_ARM
/*
* When a PCI device does not exist during config cycles, keystone host
* gets a bus error instead of returning 0xffffffff (PCI_ERROR_RESPONSE).
* This handler always returns 0 for this kind of fault.
*/
static int ks_pcie_fault(unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
{
unsigned long instr = *(unsigned long *)instruction_pointer(regs);
if ((instr & 0x0e100090) == 0x00100090) {
int reg = (instr >> 12) & 15;
regs->uregs[reg] = -1;
regs->ARM_pc += 4;
}
return 0;
}
static int __init ks_pcie_init(void)
{
/*
* PCIe access errors that result into OCP errors are caught by ARM as
* "External aborts"
*/
if (of_find_matching_node(NULL, ks_pcie_of_match))
hook_fault_code(17, ks_pcie_fault, SIGBUS, 0,
"Asynchronous external abort");
return platform_driver_register(&ks_pcie_driver);
}
device_initcall(ks_pcie_init);
#else
builtin_platform_driver(ks_pcie_driver);
#endif
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("PCIe controller driver for Texas Instruments Keystone SoCs");
MODULE_AUTHOR("Murali Karicheri <m-karicheri2@ti.com>");