Re: [PATCH v4 1/2] x86, pci: Reset PCIe devices at boot time

From: Yinghai Lu
Date: Mon Oct 15 2012 - 14:36:38 EST

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On Mon, Oct 15, 2012 at 12:00 AM, Takao Indoh
<indou.takao@xxxxxxxxxxxxxx> wrote:
> This patch resets PCIe devices at boot time by hot reset when
> "reset_devices" is specified.

how about pci devices that domain_nr is not zero ?

>
> Signed-off-by: Takao Indoh <indou.takao@xxxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/pci-direct.h | 1
> arch/x86/kernel/setup.c | 3
> arch/x86/pci/early.c | 344 ++++++++++++++++++++++++++++
> include/linux/pci.h | 2
> init/main.c | 4
> 5 files changed, 352 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/pci-direct.h b/arch/x86/include/asm/pci-direct.h
> index b1e7a45..de30db2 100644
> --- a/arch/x86/include/asm/pci-direct.h
> +++ b/arch/x86/include/asm/pci-direct.h
> @@ -18,4 +18,5 @@ extern int early_pci_allowed(void);
> extern unsigned int pci_early_dump_regs;
> extern void early_dump_pci_device(u8 bus, u8 slot, u8 func);
> extern void early_dump_pci_devices(void);
> +extern void early_reset_pcie_devices(void);
> #endif /* _ASM_X86_PCI_DIRECT_H */
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index a2bb18e..73d3425 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -987,6 +987,9 @@ void __init setup_arch(char **cmdline_p)
> generic_apic_probe();
>
> early_quirks();
> +#ifdef CONFIG_PCI
> + early_reset_pcie_devices();
> +#endif
>
> /*
> * Read APIC and some other early information from ACPI tables.
> diff --git a/arch/x86/pci/early.c b/arch/x86/pci/early.c
> index d1067d5..683b30f 100644
> --- a/arch/x86/pci/early.c
> +++ b/arch/x86/pci/early.c
> @@ -1,5 +1,6 @@
> #include <linux/kernel.h>
> #include <linux/pci.h>
> +#include <linux/bootmem.h>
> #include <asm/pci-direct.h>
> #include <asm/io.h>
> #include <asm/pci_x86.h>
> @@ -109,3 +110,346 @@ void early_dump_pci_devices(void)
> }
> }
> }
> +
> +#define PCI_EXP_SAVE_REGS 7
> +#define pcie_cap_has_devctl(type, flags) 1
> +#define pcie_cap_has_lnkctl(type, flags) \
> + ((flags & PCI_EXP_FLAGS_VERS) > 1 || \
> + (type == PCI_EXP_TYPE_ROOT_PORT || \
> + type == PCI_EXP_TYPE_ENDPOINT || \
> + type == PCI_EXP_TYPE_LEG_END))
> +#define pcie_cap_has_sltctl(type, flags) \
> + ((flags & PCI_EXP_FLAGS_VERS) > 1 || \
> + ((type == PCI_EXP_TYPE_ROOT_PORT) || \
> + (type == PCI_EXP_TYPE_DOWNSTREAM && \
> + (flags & PCI_EXP_FLAGS_SLOT))))
> +#define pcie_cap_has_rtctl(type, flags) \
> + ((flags & PCI_EXP_FLAGS_VERS) > 1 || \
> + (type == PCI_EXP_TYPE_ROOT_PORT || \
> + type == PCI_EXP_TYPE_RC_EC))
> +
> +struct save_config {
> + u32 pci[16];
> + u16 pcie[PCI_EXP_SAVE_REGS];
> +};
> +
> +struct pcie_dev {
> + int cap; /* position of PCI Express capability */
> + int flags; /* PCI_EXP_FLAGS */
> + struct save_config save; /* saved configration register */
> +};
> +
> +struct pcie_port {
> + struct list_head dev;
> + u8 secondary;
> + struct pcie_dev child[PCI_MAX_FUNCTIONS];
> +};
> +
> +static LIST_HEAD(device_list);
> +static void __init pci_udelay(int loops)
> +{
> + while (loops--) {
> + /* Approximately 1 us */
> + native_io_delay();
> + }
> +}
> +
> +/* Derived from drivers/pci/pci.c */
> +#define PCI_FIND_CAP_TTL 48
> +static int __init __pci_find_next_cap_ttl(u8 bus, u8 slot, u8 func,
> + u8 pos, int cap, int *ttl)
> +{
> + u8 id;
> +
> + while ((*ttl)--) {
> + pos = read_pci_config_byte(bus, slot, func, pos);
> + if (pos < 0x40)
> + break;
> + pos &= ~3;
> + id = read_pci_config_byte(bus, slot, func,
> + pos + PCI_CAP_LIST_ID);
> + if (id == 0xff)
> + break;
> + if (id == cap)
> + return pos;
> + pos += PCI_CAP_LIST_NEXT;
> + }
> + return 0;
> +}
> +
> +static int __init __pci_find_next_cap(u8 bus, u8 slot, u8 func, u8 pos, int cap)
> +{
> + int ttl = PCI_FIND_CAP_TTL;
> +
> + return __pci_find_next_cap_ttl(bus, slot, func, pos, cap, &ttl);
> +}
> +
> +static int __init __pci_bus_find_cap_start(u8 bus, u8 slot, u8 func,
> + u8 hdr_type)
> +{
> + u16 status;
> +
> + status = read_pci_config_16(bus, slot, func, PCI_STATUS);
> + if (!(status & PCI_STATUS_CAP_LIST))
> + return 0;
> +
> + switch (hdr_type) {
> + case PCI_HEADER_TYPE_NORMAL:
> + case PCI_HEADER_TYPE_BRIDGE:
> + return PCI_CAPABILITY_LIST;
> + case PCI_HEADER_TYPE_CARDBUS:
> + return PCI_CB_CAPABILITY_LIST;
> + default:
> + return 0;
> + }
> +
> + return 0;
> +}
> +
> +static int __init early_pci_find_capability(u8 bus, u8 slot, u8 func, int cap)
> +{
> + int pos;
> + u8 type = read_pci_config_byte(bus, slot, func, PCI_HEADER_TYPE);
> +
> + pos = __pci_bus_find_cap_start(bus, slot, func, type & 0x7f);
> + if (pos)
> + pos = __pci_find_next_cap(bus, slot, func, pos, cap);
> +
> + return pos;
> +}
> +
> +static void __init do_reset(u8 bus, u8 slot, u8 func)
> +{
> + u16 ctrl;
> +
> + printk(KERN_INFO "pci 0000:%02x:%02x.%d reset\n", bus, slot, func);
> +
> + /* Assert Secondary Bus Reset */
> + ctrl = read_pci_config_16(bus, slot, func, PCI_BRIDGE_CONTROL);
> + ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
> + write_pci_config_16(bus, slot, func, PCI_BRIDGE_CONTROL, ctrl);
> +
> + /*
> + * PCIe spec requires software to ensure a minimum reset duration
> + * (Trst == 1ms). We have here 5ms safety margin because pci_udelay is
> + * not precise.
> + */
> + pci_udelay(5000);
> +
> + /* De-assert Secondary Bus Reset */
> + ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
> + write_pci_config_16(bus, slot, func, PCI_BRIDGE_CONTROL, ctrl);
> +}
> +
> +static void __init save_state(unsigned bus, unsigned slot, unsigned func,
> + struct pcie_dev *dev)
> +{
> + int i;
> + int pcie, flags, pcie_type;
> + struct save_config *save;
> +
> + pcie = dev->cap;
> + flags = dev->flags;
> + pcie_type = (flags & PCI_EXP_FLAGS_TYPE) >> 4;
> + save = &dev->save;
> +
> + printk(KERN_INFO "pci 0000:%02x:%02x.%d save state\n", bus, slot, func);
> +
> + for (i = 0; i < 16; i++)
> + save->pci[i] = read_pci_config(bus, slot, func, i * 4);
> + i = 0;
> + if (pcie_cap_has_devctl(pcie_type, flags))
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_DEVCTL);
> + if (pcie_cap_has_lnkctl(pcie_type, flags))
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_LNKCTL);
> + if (pcie_cap_has_sltctl(pcie_type, flags))
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_SLTCTL);
> + if (pcie_cap_has_rtctl(pcie_type, flags))
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_RTCTL);
> +
> + if ((flags & PCI_EXP_FLAGS_VERS) >= 2) {
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_DEVCTL2);
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_LNKCTL2);
> + save->pcie[i++] = read_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_SLTCTL2);
> + }
> +}
> +
> +static void __init restore_state(unsigned bus, unsigned slot, unsigned func,
> + struct pcie_dev *dev)
> +{
> + int i = 0;
> + int pcie, flags, pcie_type;
> + struct save_config *save;
> +
> + pcie = dev->cap;
> + flags = dev->flags;
> + pcie_type = (flags & PCI_EXP_FLAGS_TYPE) >> 4;
> + save = &dev->save;
> +
> + printk(KERN_INFO "pci 0000:%02x:%02x.%d restore state\n",
> + bus, slot, func);
> +
> + if (pcie_cap_has_devctl(pcie_type, flags))
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_DEVCTL, save->pcie[i++]);
> + if (pcie_cap_has_lnkctl(pcie_type, flags))
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_LNKCTL, save->pcie[i++]);
> + if (pcie_cap_has_sltctl(pcie_type, flags))
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_SLTCTL, save->pcie[i++]);
> + if (pcie_cap_has_rtctl(pcie_type, flags))
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_RTCTL, save->pcie[i++]);
> +
> + if ((flags & PCI_EXP_FLAGS_VERS) >= 2) {
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_DEVCTL2, save->pcie[i++]);
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_LNKCTL2, save->pcie[i++]);
> + write_pci_config_16(bus, slot, func,
> + pcie + PCI_EXP_SLTCTL2, save->pcie[i++]);
> + }
> +
> + for (i = 15; i >= 0; i--)
> + write_pci_config(bus, slot, func, i * 4, save->pci[i]);
> +}

do you have to pass bus/slot/func and use read/pci_config directly ?

I had one patchset that use dummy pci device and reuse existing late quirk code
in early_quirk to do usb handoff early.

please check

git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git
for-x86-early-quirk-usb

678a023: x86: usb handoff in early_quirk
2d418d8: pci, usb: Make usb handoff func all take base remapping
d9bd1ad: x86, pci: add dummy pci device for early stage
de38757: x86: early_quirk check all bus/dev/func in domain 0
325cc7a: make msleep to do mdelay before scheduler is running
eec78a4: x86: set percpu cpu_info lpj to default
52ebec4: x86, pci: early dump skip device the same way as later probe code

if that could help.
you may reuse some later functions that take pci_dev as parameters.
also mdelay should work early...
and use early_quirk instead add another calling in setup.c

Yinghai
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Next message: Jesper Juhl: "[PATCH] [resend] ACPI: Fix memory leak in acpi_bind_one() (fwd)"
Previous message: Stefan Hajnoczi: "[PATCH] staging: line6: drop unused line6_devices[] array"
In reply to: Khalid Aziz: "Re: [PATCH v4 1/2] x86, pci: Reset PCIe devices at boot time"
Next in thread: Takao Indoh: "[PATCH v4 2/2] x86, pci: Enable PCI INTx when MSI is disabled"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]