Commit bc10d0ad authored by Siddharth Vadapalli's avatar Siddharth Vadapalli Committed by Bjorn Helgaas
Browse files

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



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: default avatarSiddharth Vadapalli <s-vadapalli@ti.com>
[mani: added a note about hook_fault_code()]
Signed-off-by: default avatarManivannan Sadhasivam <mani@kernel.org>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20251029080547.1253757-5-s-vadapalli@ti.com
parent 5aa84c03

drivers/pci/controller/dwc/Kconfig

+11 −4
Original line number Diff line number Diff line
@@ -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

drivers/pci/controller/dwc/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -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

drivers/pci/controller/dwc/pci-keystone.c

+45 −33
Original line number Diff line number Diff line
@@ -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>");